Below, the invention will be explained in detail based on the embodiments that are depicted in the drawing. Here:
FIG. 1 shows, greatly simplified diagrammatically, a cutaway and half-page longitudinal section of adjacent pipe pieces of an exhaust gas pipe, the pipe pieces being mutually sealed by a sealing system according to an embodiment of the invention;
FIGS. 2 and 3 show longitudinal sections, similar to FIG. 1, of a second or third embodiment of the sealing system;
FIG. 4 shows a half-page longitudinal section of only the joint area of the adjacent flange parts of two pipe pieces, provided with a fourth embodiment of the sealing system, and
FIGS. 5 and 6 show similar depictions, provided with a fifth or sixth embodiment of the sealing system.
In the FIGS., a first pipe piece and a second pipe piece of an exhaust gas pipe are referred to as 1 or as 3. During operation of the respective internal combustion engine, the exhaust gas pipe of an exhaust gas heat flow 5 with a corresponding high exhaust gas temperature results. The pipe pieces 1 and 3 that are to be connected to one another and that are to seal against one another by means of the sealing system according to the invention in each case have a flange part 9 or 11 that projects radially outward relative to the pipe axis 7. The flange parts 9 and 11 together form a ring flange 13, the flange parts 9 and 11 having faces 15 or 17 that face one another. To connect the pipe pieces 1 and 3 to one another, the flange parts 9, 11 of the ring flange 13 are clamped to one another by suitable tensioning means, of which only tensioning means of the usual type in FIGS. 1 and 2 are indicated heavily schematized, in FIG. 1, tension rings 19 with threaded joints 21 being shown, and in FIG. 2, a tension ring 27 accommodated on bevelings 25 of the flange parts 9 and 11 being shown.
For the seal between the flange parts 9 and 11, FIG. 1 shows a two-layer metal crimping seal 29, while in the examples of FIGS. 2 to 6 in each case, a metal mold seal 31 of a C-shaped profile cross-section is shown. In each instance, the respective sealing element is chambered to some extent in a receiving space 33 that is formed between the flange parts 9 and 11. In the example of FIG. 1, the receiving space, which is open on the outer peripheral side on ring flange 13, is bordered axially by the faces 15 and 17 of the flange parts 9 or 11 and is bordered radially inside by an insertion element, in which the example of FIG. 1 is a metal fire ring 35, which is inserted between the flange parts 9 and 11 and borders the receiving space 33 with its radial outer annular edge 37.
Apart from the other tensioning means (tension ring 27), however, the example of FIG. 2 differs mainly in the respect that instead of the crimping seal 29, a mold seal 31 is installed in the receiving space 33 and that instead of the fire ring 35, a non-metallic insertion element is inserted between the flange parts 9 and 11, specifically a ring element 39 that is made of a material of poor heat conductivity. As materials for this purpose, for example, i.a., ceramic fiber materials, for example made of amorphous aluminum silicate fibers or crystalline aluminum oxide fibers, are suitable or any materials that form an effective heat shield between heat flow 5 and receiving space 33. The insertion element can also consist of a modern composite material, for example, can be formed from metallic or non-metallic material, which in the corresponding compound ensures a good heat shield.
FIG. 3 shows an embodiment in which the receiving space 33 is formed by a ring-shaped recess 41, which is created in the flange part 9 of its peripheral edge 43 such that the receiving space 33 is bordered axially by the face 17 of the flange part 11 and the opposite wall of the recess in the flange part 9. Analogous to the examples of FIGS. 1 and 2, the sealing element is thus accommodated in a receiving space 33 and partially chambered, the receiving space 33 in turn being located on the end of the ring flange 13 that is furthest out in the radial direction, i.e., in the range that has the lowest operating temperature. In modifying the embodiment according to FIG. 3, the receiving space 33 can also be formed by two ring-shaped recesses that face one another, which are created in each case in the flange part 9 as well as 11 of its peripheral edge, such that then the sealing element is arranged in approximately the middle with its C-shaped opening edge along the face between the two flange parts 9 and 11.
FIGS. 4 to 6 show embodiments in which the receiving space 33 in each case is formed by an annular groove 45, which is created recessed in axial direction in the flange part 11 of its face 17, whereby in connection with the face 15 of the flange part 9, a closed chamber for the mold seal 31 is formed.
In the examples of FIGS. 4 to 6, as an additional heat protection for the mold seal 31 that is located in the receiving space 33, in each case a cover element 47, which is inserted into the annular groove 45, in the form of a metal ring element is provided. The example of FIG. 4 is a flat ring element, while as cover elements 47 in the examples of FIGS. 5 and 6, profile rings are provided, specifically a curved ring in FIG. 5 and an angled ring in the example of FIG. 6. In any case, the cover element 47 is installed in the annular groove 45 such that the mold seal 31 is covered at least on the side that is facing the point of impact between the faces 15 and 17 of the flange part 9 or 11. As indicated in FIG. 4 by a flow arrow 49, the section of the point of impact between the faces 15 and 17 that is closest to the heat flow 5 is most heavily affected by the heat flow, against which that section of the cover element 47 facing the point of impact forms a shield.
Patent Application
20080073857
