Sealing system for exhaust-gas lines

A sealing system, in particular for sealing multiple part exhaust-gas lines for an internal combustion engine, has at least a first flange part (9) and a second flange part (11) guiding a flow of heat (5). The flange parts (9, 11) delimit a receiving space (33) for at least one sealing element (31) between them and adjoin one another. Each flange part forms an outwardly projecting annular flange (13) facing away from the flow of heat (5), and extending transversely with respect to the heat flow. Chambering of the receiving space (33) is formed for the sealing element (31) by an annular groove (45) open at the end face (17) of at least one flange part (11) and recessed axially into said end face (17). At least one covering element (47) is arranged in the annular groove (45) and provides thermal shielding for the sealing element (31) at least on its side facing the end face (17) of the flange part (11).

FIELD OF THE INVENTION

The invention relates to a sealing system, in particular for sealing of multipart exhaust-gas lines for an internal combustion engine, having at least first and second flange parts. The flange parts conduct a heat flow and delimit a receiving space for at least one sealing element between them.

BACKGROUND OF THE INVENTION

Sealing systems of this type are known. DE 10 2004 060 845 A1 shows, for example, such a sealing system for the exhaust gas line of a reciprocating piston engine. The sealing element is a metallic gasket in the form of a profile body with a C-shaped profile cross section. Sealing elements on exhaust gas lines are subject to very high temperatures which can exceed 600° C. Even if materials are used with properties that are suitable with respect to heat resistance, the sealing elements at the prevailing high operating temperatures lose their functional properties required for sealing. Especially the elasticity of the sealing elements is reduced by creep processes due to overly high thermal loads.

SUMMARY OF THE INVENTION

Accordingly, an object of the invention is to provide a sealing system which, when used in a hot gas region, ensures reliable sealing even when high temperatures occur on the exhaust gas lines to be sealed.

According to the invention, this object is basically achieved by a sealing system having flange parts to be sealed against one another and to form an annular flange facing away from the heat flow and projecting transversely to the heat flow to the outside. A chambering is formed for the sealing element. The material of the annular flange forms a certain thermal shielding of the sealing element relative to the heat flow. The sealing element chambered in an annular groove is additionally protected by a cover element within the annular groove forming thermal shielding at least on the side of the sealing element facing the end face of the flange part, i.e., on the open side of the annular groove which is thermally most heavily loaded. The sealing element is protected especially effectively against overly high thermal loads such that the system according to the invention can also be reliably used on exhaust gas lines which are thermally highly loaded.

Preferably, the cover element is a metallic annular body.

When there is an annular body in the form of a flat ring, it is preferably inserted such that it extends between the sealing element and the facing end face of the flange part, and thus, forms a thermal barrier on the region of the annular groove most heavily thermally loaded and in which the sealing element is chambered.

Instead of a flat annular body, the cover element can be formed by a profile ring having an arched profile or an angled profile.

In such embodiments the annular body is preferably inserted into the annular groove such that it surrounds the sealing element both on the side facing the end face and on the side facing another wall of the receiving space.

Especially good thermal shielding of the sealing element in such embodiments can be achieved when the cover element also surrounds the sealing element on the side nearest the heat flow, that is, on that side facing the radially inside wall of the annular groove.

The sealing element is preferably a molded ring seal, with a C-shaped or V-shaped profile cross section. In this case, the sealing element with the C-profile is preferably installed in the annular groove such that the profile is open radially to the inside, that is, towards the pressure side of the system.

Instead of a V-shaped or C-shaped profile cross section, the sealing element could also have a meandering profile cross section, in the form of a bellows solution in which several folds lying on top of one another form the cross section.

Alternatively, metal bead seals can be installed in the receiving space. In any case, the invention ensures thermal protection for the respective sealing element so that for metallic sealing elements of a material available for high temperature use, reliable sealing in hot gas regions is ensured. The annular shape for the sealing element can be circular or nearly circular. Furthermore, ring shapes are conceivable in the form of an oval or a rectangular shape, preferably with rounded corner regions. The respective annular groove must then preferably follow the pertinent ring shape of the sealing element.

Other objects, advantages and salient features of the present invention will become apparent from the following detailed description, which, taken in conjunction with the annexed drawings, discloses preferred embodiments of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

In the figures, a first line section and a second line section of an exhaust gas line or other hot fluid conduit are designated as1and3, respectively. In the operation of the pertinent internal combustion engine, the exhaust gas line conducts an exhaust gas-heat flow5with a correspondingly high exhaust gas temperature. The line sections1and3are sealed against one another by the sealing system according to the invention and are to be connected to one another. Each line section has a flange part9and11respectively projecting radially to the outside relative to the axis7of the line. The flange parts9and11together form an annular flange13and have end faces15and17facing one another. To connect the line sections1and3to one another, the flange parts9,11of the annular flange13are braced to one another by suitable clamping means which may be conventional and which are therefore not shown. For example, the clamping means could be a clamping ring pulled onto peripheral bevels25of the flange parts9and11(not shown).

The sealing element for sealing between the flange parts9and11is a metallic molded ring seal31with a C-shaped profile cross section. As indicated above, a molded ring seal with a different profile cross section or a bead seal or the like could be used. In any case, the sealing element is at least partially chambered and is enclosed in a receiving space33formed between the flange parts9and11. As shown in the drawings, in the embodiments ofFIGS. 1 to 3, the receiving space33is formed by an annular groove45machined and recessed in the axial direction in the flange part11from its end surface17and opening only on end face17. The end face15of the flange part9closes the chamber for the molded ring seal31.

According to the invention, additional heat protection for the molded ring seal31located in the receiving space33is a cover element47inserted into the annular groove45. The cover element47forms a thermal barrier between the molded ring seal31and the thermally most heavily loaded region of the receiving space33. In the embodiment ofFIG. 1, the cover element47is formed by a flat metal ring inserted between the molded ring seal31and the end surface17bordering the end face15of the opposite flange part9. As the flow arrow49indicates, this junction site is most heavily under the influence of the heat flow5so that the cover element47has the greatest protective effect in this position.

In the embodiment ofFIG. 2, instead of a flat ring the cover element47has an arched annular body installed in the annular groove45such that it shields not only that side of the molded ring seal31bordering the open side of the annular space45and forming a barrier there in the same manner as in the example ofFIG. 1, but, moreover, with an arched region extends over the molded ring seal31such that it is also shielded relative to the radially inner wall of the annular groove45, i.e., against the wall of the receiving space nearest the heat flow5.

FIG. 3illustrates another embodiment in which the cover element47likewise forms a shield on two sides of the molded ring seal31. For this purpose, the cover element47is made as an angled profile ring. A profile leg, corresponding to the flat annular body ofFIG. 1, extends along the junction site between the end faces17and15. The angled other profile leg in corresponds to the arched profile part of the cover element47ofFIG. 2and forms the shielding relative to the wall of the receiving space33nearest the heat flow5.

Instead of the illustrated forms of the cover element47, other profile cross sections could be used. For example, a U profile surrounding the sealing element along three sides can be used. In any case, the cover element47is installed in the annular groove45such that the molded ring seal31is covered at least on the side facing the junction site between the end faces15and17of the flange parts9and11. Preferably, in addition, the correspondingly shaped cover element47extends over the molded ring seal31on at least one other thermally endangered site.