Flat seal
Description
The invention relates to a flat seal, in particular an exhaust-side seal for an internal combustion engine.
Metallic seals are currently used for such seals. The choice of material for such a seal depends here on the maximum temperature and the continuous operating temperature. Modern engines place ever higher demands on seal technology because of the constant increase in both combustion pressures and combustion temperatures. This means that materials of ever higher quality must be used to satisfy these demands.
EP 0 955 489 Bl describes a metal seal having different surface pressure areas, comprising a first, a second and a third metal plate, said first and said second metal plate having embossed areas and said third metal plate being operatively connected to the first and second metal plate by providing a flange on an inner area.
JP 02286859 A describes a cylinder head gasket, which has fastening elements, located around media through-holes, for receiving inserts.
The object of the invention is to provide a flat seal, in particular an exhaust-side seal for an internal combustion engine, in which, by optimising the materials being used, the price is reduced compared with conventional flat seals and there shall be a simpler mechanical design.
This object is achieved by a flat seal, in particular an exhaust-side seal for an internal combustion engine, formed by a sealing element that has at least one layer and is provided with a cut-out, said sealing element being made of a high-quality metallic material, in particular having a high heat resistance, and by a support element that receives the sealing element, said support element being made of a lower quality metallic material and receiving and carrying the sealing element in such a way that the sealing element can be fixed and fitted.
The subclaims relate to advantageous developments of the invention.
The subject matter of the invention thus provides a type of hybrid solution made of two different materials, where only the relatively narrow sealing area exposed to higher temperatures is formed by a sealing element made of a very high-quality heat-resistant material. A sheet made of far cheaper material can be used as the support element for this sealing element, the essential purpose of said sheet being only to achieve suitable installed thicknesses, to connect together a plurality of sealing elements if necessary, and to construct the entire seal so that it can be fitted and fixed.
A significant cost benefit compared with previously used solutions can be achieved by a selective combination of suitable materials, because the entire seal no longer needs to be made of high-quality materials, but instead such materials are now only used in parts of the seal, namely in the sealing areas.
The sealing element and the support element are advantageously connected by mechanical means by clamping.
A flat seal according to the invention can advantageously be used as an exhaust flange seal.
In addition, a method for manufacturing the flat seal is proposed, in which a sealing element having at least one layer and a definable contour is made by punching, in which a single support element, or a plurality of elements that are joined to form one support element, is made by punching, said support element having a punched hole, in which tabs are punched out of the support element or elements respectively on the sealing-element side, in which tabs are opened up at least partially, in which the sealing element is placed on individual members of the tabs, and in which additional tabs are bent back towards the sealing element forming a snap-fit fastening.
The form of mechanical connection is easy to manufacture and can be produced using commercially available technologies.
The tabs can act as additional sealing means by suitable compression. For example, they can be used for micro-sealing if the support sheet is made of a material that is sufficiently soft and hence able to yield. The tabs can also act as stopper elements, provided the material of the support sheet is sufficiently firm or stiff. Another advantage of using such tabs for clamping is that it is possible to set the thermal conductivity, i.e. the heat transfer, by the number and shape of the tabs. This means it is possible to combine even very different materials that have very different operating temperature ranges.
The form of clamping can also be used to set whether there is, or is meant to be, any play (radial play) between the sealing element and the support element, and if so, how much. It is thereby possible to compensate for any differences in thermal expansion properties and the associated thermally induced stresses of the two materials.
In particular, Ni-Cr-Fe alloys are suitable materials for the sealing element, where other heat-resistant alloys may also be used. The support element can be made of a commercially available steel, e.g. cold rolled strip.
The subject matter of the invention is described below and presented with reference to an exemplary embodiment in the drawing, in which:
Figures 1 and 2 show the fundamental design of the flat seal according to the invention
comprising support element and sealing element;
Figures 3 and 4 show sections through connection variants between support element
and sealing element;
Figure 5 shows an alternative embodiment to Figures 3 and 4;
Figure 6 shows an alternative embodiment to Figures 1 and 2.
Figures 1 and 2 show alternative embodiments of the flat seal 1 according to the invention that can be used as an exhaust flange seal. Identical components are labelled with the same reference signs. The figures show a support element 2, for example made of cold rolled strip, which is provided with a punched hole 3. A sealing element 4 containing a cut-out 4' is carried inside this punched hole 3 and mechanically connected in the form of a snap-fit fastening to the support element 2 by means of tabs 5 (only shown as an indication) formed out of the support element 2. The tabs 5 are opened out in an opposite direction, so that some of them are positioned above the sealing element 4 and the others below the sealing element 4. The sealing element 4 is made of a heat-resistance Ni-Fe-Cr alloy in this example and is carried inside the punched hole 3 of the support element 2 in such a way that it can be fixed and fitted easily.
Figures 3 and 4 show sections through connection variants between support element 2 and sealing element 4. In each figure, the top illustration shows the opened-out tabs 5 and the unattached lip 6 of the sealing element 4, which initially rests on the lower tabs 5 of the support element 2. The illustration at the bottom of Figures 3 and 4 shows the situation in which the upper tabs 5 have been bent back and hence carry the lip 6 between them and hold it in a clamped position. The sealing element 4 is provided with an embossed area 7 outside the unattached lip 6.
Both the support element 2 and the sealing element 4 are punched from suitable sheet-type semi-finished products, where the punched hole 3 of the support element 2 matches the outer contour of the sealing element 4. On the punched-hole side, tabs 5 are additionally punched and opened out in an opposite direction. The sealing element 4 is placed onto individual lower tabs 5 and then the upper tabs 5 are bent back towards the sealing element 4 so that they lie, as can be seen in Figures 3 and 4, on the unattached lip 6 of the sealing element 4.
Figure 5 shows an alternative embodiment to Figures 3 and 4. In Figures 3 and 4, projecting pieces of material are formed axially outside the lip 6 by the tabs 5.
Figure 5 shows an embodiment in which the tabs 5 of the support element 2 are provided in the same plane as the sealing element 4, i.e. the tabs 5 are inserted in radial recesses 8 of the sealing element 4.
Figure 6 shows an alternative embodiment of a flat seal 9 compared with Figures 1 and 2. Although it contains the same type of components, namely a support element 10 and a sealing element 11, they are connected together operatively in a different manner. The support element 10 contains a punched hole 12, whereas the sealing element 11 is provided with a cut-out 11'. The punched hole 12 and the cut-out 11' are designed to be congruent. Since the sealing element 11 is not positioned inside the punched hole of the support element, unlike the situation shown in Figures 1 and 2, a different type of connection must be effected here. The sealing element 11 is positioned in an aligned form i.e. concentric with the punched hole 12. Tabs 13 have been formed out of the solid material of the support element 10. These tabs shall be considered equivalent to those shown in Figures 1 and 2, with the difference that there is only an upper tab 13, because the sealing element 11 rests on the support element 10 by its radial wall thickness.

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We Claims:-
New claims
1. Exhaust-side seal for an internal combustion engine, formed by a sealing element (4,11) that has at least one layer and is provided with a cut-out (4',11'), said sealing element being made of a high-quality heat-resistant metallic Ni-Cr-Fe material, and by a support element (2,10) that receives the sealing element (4,11), said support element (2, 10) being made of a lower quality cold rolled strip steel and receiving and carrying the sealing element (4,11) so that the sealing element (4,11) can be fixed and fitted, and being designed such that the support element (10) has a punched hole (12), which matches the cut-out (11') of the sealing element (11), so that the sealing element (11) rests on the support element (10), and the sealing element (11) is held by deformable tabs (13) acting as stopper elements.
2. Flat seal according to Claim 1, characterized in that the connection between sealing element (4,11) and support element (2,10) is effected by mechanical means by clamping.
3. Flat seal according to Claim 1 or 2, characterized in that the sealing element (2) is provided with at least one circumferential embossed ridge (7).
4. Flat seal according to Claim 3, characterized in that a defined radial play can be set between the sealing element (4) and the support element (2).
5. Flat seal according to any of Claims 1 to 4 that can be used as an exhaust flange seal.
6. Method for manufacturing a seal (1) according to any of Claims 1 to 5, characterized in that a sealing element (4,11) having at least one layer and a definable contour is made by punching, that a single support element (2,10), or a plurality of elements that are joined to form one support element (2,10), is made by punching, said support element (2,10) having a punched hole (3,12), that tabs (5,13) are punched out of the support element (2,10) or elements respectively on the sealing-element side, that tabs (5,13) are opened up at least partially, that the sealing element (4,11) is placed on
individual members of the tabs (5,13) or respectively the support element (10), and that additional tabs (5) or respectively the tabs (13) are bent back towards the sealing element (4,10) forming a snap-fit fastening.