Flange connection with a multi-layer seal.

The invention relates to a flanged connection comprising two metallic flanges, which assume temperatures different Tempe in operation, as well as a between the flanges pressed with prestress multi-layer seal which is arranged a middle layer formed by a flat metal layer and on both sides of this, in each case on one of the flanges fitting, formed of sealing material outer layers contains.

Such flanged joints are known and are used in many different machines and systems, but problems concerning the sealing of the flange and the creep strength of the seal contained therein may occur, which are caused by a delay of the flanges and relative sliding movements of the flanges. These problems arise to a greater extent on when the flange very high temperatures and / or frequent hot-cold cycles is exposed. Such difficult operating conditions are particularly given in the flange between the cylinder head and exhaust manifold on internal combustion engines, wherein the seals still additional burdens are exposed by the fact that several flange connections are arranged nebeineinander usually, one of which flanges are connected by the cylinder head rigidly, while the other flanges are rigidly connected through the exhaust manifold, which suffers temperature- and aging-related deformations.

Object of the invention is to develop a flange connection of the aforementioned type so that even at high temperatures, hot-cold cycles, as well as distortions and relative sliding movements of its flanges, a reliable seal is given and a sufficient life of the seal is achieved.

This object is achieved in that the first, on which the lower temperature having flange fitting outer layer of the seal consists of an elastomer layer, that the second of the higher temperature having flange fitting outer layer of a layer structured from flake-like or fibrous inorganic, thermally insulating material and that the metal layer comprises aluminum sheet or on its side facing the flange having the higher temperature side is provided with an aluminum coating steel sheet.

Although it is known that elastomers can compensate even large bumps of counter surfaces to be sealed as a sealing material.

Experts were but so far caught by the prejudice that the use of elastomers by the maximum temperature at the installation site, ie the temperature of the warmest flange is limited. In contrast, uses the finding of the invention that the use of an elastomer layer is only limited by the temperature of the colder of the two flanges, namely when this layer is shielded from the warmer flange through a heat insulating layer and at the warmer flange one whose temperature matched, ie compared to elastomers rests wärmebeständigere layer of sealing material. A further finding of the invention is that the considerable elastic deformability of the elastomer layer also improves the more limited se adaptability of temperature-resistant layer, and thus its sealing effect, ensuring the flange is at a.

In a preferred embodiment of the invention is contained in the second layer of inorganic heat insulating material made of mica, while the elastomer layer is made of a fluoroelastomer and the metal layer is formed of a stainless steel sheet.

According to a development of the invention, at least the metal layer of the seal projects laterally on the flanges and forms a heat-shielding. This allows heat-sensitive components to easily protect against heat, for example, to the declaration issued by convection and radiant heat of an exhaust manifold. According to another expedient embodiment, the metal layers of multiple seals at least are connected by an integrally formed web together, so that a so-called group seal.

According to a preferred embodiment of the invention the plurality of seals connecting web is at least partially formed by the heat-shielding, so that a group of seal is obtained with heat-shielding. If a greater stiffness or heat-shielding effect of the webs and / or the heat-shielding desired, the seal extend over the surface on the flanges protruding extensions of the first and / or second layers (outer layers) completely or partially.

Embodiments of the invention will be explained with reference to the drawings, in which:<ul><li>FIG. 1 is a partially sectioned side view of a flange;</li><li>FIG. 2 is a plan view of an insertable in the flange of Figure 1 seal, said in broken lines a further illustrated as a multiple seal.</li><li>Figure 3 is a section on an enlarged scale of the detail E in Figure 1 for a first embodiment of the gasket..; </li><li>Fig. 4 shows a section in vergrößertemMaßstab the detail E in Fig. 1 and for a second embodiment of the seal</li><li>Fig. 5 is a perspective view of a modification having a plurality of seals connected to each other and a molded heat-shielding surface.</li></ul>

The flange connection according to the invention, which essentially consists of two flanges 1, 2 and a seal 3 will be explained hereinafter for its preferred embodiment as a connection between the cylinder head 1 and the exhaust manifold 2 'of a internal combustion engine. Here the operation takes the cylinder head 1 'fixed flange 1 due to cooling of the cylinder head has a lower temperature than at the at the more heated by the exhaust manifolds 2' fitting flange. 2

Formed as a flat sealing gasket 3 is clamped between the flat bearing surfaces of the flanges 1, 2 which are held together by bolts 4 and nuts 5, which two holes 6 penetrating the seal. The seal 3 comprises in one illustrated by the Fig. 3 embodiment, the first three-surface layers 7, 8 and 9. The middle metal layer 7 is made of aluminum sheet or an aluminum foil. This is on the side which faces the lower temperature having flange 1, covered with an elastomer layer. 8 As the material for this layer comprises a fluoroelastomer is particularly suitable. The other, the higher tempering temperature having flange 2 facing side of the metal layer 7 is covered with a layer 9 of mica.

The layers 8 and 9 are connected by bonding with the metal layer. 7 In the case of the layer 8 may also be effected by vulcanization the connection. Additionally or alternatively, for bonding or vulcanization, each of the layers 8, 9 with the metal layer 7 through of this punched, bent outwards skewers and / or embracing by the central passage opening 10 as a flange, the seal before the attack of the exhaust gases protective edging 11 may be joined from sheet metal. Such curbs may also be provided on the outer periphery of the seal 3 and / or to the holes. 6

A second embodiment (Fig. 4) corresponds to the above-described sealing, but contains a metal layer, which is composed of a steel sheet or stainless steel sheet 7 'and 7˝ an aluminum covering. The aluminum covering 7˝ can be applied to the steel sheet 7 'as a carrier material, for example by spraying or vapor deposition. It can also be formed by an aluminum film, which is' connected to the sheet steel 7 by one of the mounting methods, as discussed above for the first embodiment of the seal. In any case, the aluminum surface is 7˝ arranged on the side of the steel sheet 7 ', which is facing the flange 2 at the higher temperature, ie, the layer 9 of mica connects to the aluminum coating.

Fig. 2 shows in consideration also of the system illustrated in dotted lines part of a group sealing are connected with each other at the two seals 3, 3 'by a web 12. This web consists of at least the integrally interconnected metal layers 7 of the two seals. If a greater stiffness of the web 12 is desired or this can be tolerated, then one or both of the outer layers (elastomer layer or mica layer) over the web can extend away in one piece. If the stiffness of the web 12 in particular to tensile and compressive stresses in the plane of the seal can be reduced, the bridge receives an over its entire width extending bead.

One for special use between the flanges on the one hand to the cylinder head, the other hand on the exhaust manifold suitable embodiment the seal is illustrated in Fig. 5. The individual seals 3, 3 'and 3˝ are integrally connected by webs 12 to a common large-scale screening surface 13, which therefore both a part of the individual seals uniting a group sealing web forms, and the heat-shielding is used. Despite the combination of the individual seals 3, 3 ', 3˝ they can follow the movements of their associated flanges virtually unhindered, because the webs 12 extend at least approximately in the vertical direction to a defined by the centers of the holes 10 of the seals straight and in its width is reduced by slots or openings.