WO2005022009A2

WO2005022009A2 - Flat gasket, in particular a metal gasket

Info

Publication number: WO2005022009A2
Application number: PCT/EP2004/008535
Authority: WO
Inventors: Friedhelm Stecher; Christoph Stecher
Original assignee: STE Gesellschaft für Dichtungstechnik mbH
Priority date: 2003-08-22
Filing date: 2004-07-29
Publication date: 2005-03-10
Also published as: DE10338725A1; WO2005022009A8; WO2005022009A3

Abstract

The invention relates to a flat gasket (1) comprising at least one sealing layer (2) provided with at least one through opening (3) completely surrounded at least on one side thereof by a closed and shaped sealing surface (4) which is made of a material which is stable with respect to the height thereof, which is creeping and pressure resistant during operation, and which is provided with a raised profile which substantially corresponds to the topography of a sealing gap formed between the opposite sealing surfaces and optionally other sealing layers (12). The inventive flat gasket (1) is produced by inserting a sealing surface into a sealing plate (2) in such a way that the thickness thereof (2) is at least partially reduced with respect to the initial thickness (D) thereof (2) in the sealing surface area (4), exhibiting one of the following characteristics: a) a coating (12) whose total thickness together with the sealing surface height is greater than the initial thickness (D) of the sealing plate (2) is arranged in the region of the sealing surface (4); b) areas of the sealing plate (2) extending outside the sealing surface (4) and having a thickness at least equal to the initial thickness (D) of the sealing plate (2) are completely removed; and c) areas of the sealing plate (2) extending out of the sealing surface and having a thickness at least equal to the initial thickness (D) of the sealing plate (2) are bent out of the sealing plate (2) plane.

Description

FLAT SEAL, ESPECIALLY METALLIC FLAT SEAL

The invention relates to a flat gasket and in particular a metallic flat gasket, in which a through-opening to be sealed is completely surrounded by a raised sealing surface, which consists of a pressure-resistant and creep-resistant material that is not vertically deformable and has a height profile, which, if appropriate with the inclusion of further sealing layers present in the seal, is designed according to the topography of the sealing gap formed between the counter surfaces to be sealed. Such seals have already been described by the applicant in EP 0485693 A1 and DE 4421219 A1. The difference between these seals and such seals, in which the passage opening is sealed with an elastic sealing element such as a bead, is that the seals are stable and non-elastically deformable, at least in all areas where they are used, and from the start the deflections of the counter surfaces to be sealed that occur during operation are topographically adapted. In this way, uniform surface pressures can be achieved with comparatively low screw forces. In order to improve the micro-sealing of the seals described, small raised sealing webs can additionally be present on the topographically formed sealing surfaces, as is described in WO 97/01722 A1. In addition, the seals can be completely or partially coated.

In the manufacture of the topographic seals, the raised sealing surfaces can be machined out of a sealing plate by machining. Another manufacturing variant uses an embossing process. On the one hand, the topographically formed sealing surfaces can first be embossed and then the non-embossed, higher areas can be removed by machining. On the other hand, in the areas in which the raised sealing surfaces are to be created, greater material thicknesses can be achieved by material accumulation, and then the desired topographical configuration is produced by an embossing step. All of the manufacturing processes described are comparatively complex, time-consuming and expensive. While the described topographic seals provide excellent sealing results in most applications, there are still some special uses in which a more flexible and versatile adaptation of the seals to the existing conditions would be desirable. For example, there are applications in which one and the same seal is used to seal different adjacent parts, in which the sealing requirements are different.

One example of this is the sealing of an engine block with an adjacent chain case by means of a cylinder head gasket. The cracks that occur between the two parts, with their manufacturing and assembly tolerances, cannot be sealed with the known, stable, topographical seals.

Another example in which the known stable topographic seals do not provide completely satisfactory results is the sealing of sealing surfaces which are composed of different materials. An example from the engine sector can also be given here. For example, motors are now known which consist of aluminum and magnesium, usually for weight reduction. For example, the aluminum core encompasses the combustion chamber openings, while oil openings and water openings are provided in the magnesium jacket.

With regard to the sealing of such an engine with a cylinder head gasket, it is problematic here on the one hand that the magnesium outer part is relatively soft and can absorb very low screw forces if necessary. For this reason, a cylinder head gasket is difficult to attach in this area and the surface pressures that can be achieved are low. Stable topographical seals are only poorly suited for sealing this area, since they are only insufficiently supported there, may dig into the soft contact surfaces and leakages can occur. On the other hand, the different coefficients of thermal expansion of the materials aluminum and magnesium cause great problems when sealing. The magnesium tends to grow out of the sealing surface under high thermal loads. This means that the sealing gap to be sealed changes depending on the temperature. These sealing requirements are also difficult to meet with conventional seals.

A task of the invention is accordingly to provide a seal of the type described in the introduction, which is simple and inexpensive to produce, can be adapted to the most varied sealing conditions in a simple manner and thereby achieves a reliable seal. This object is achieved with the flat gasket according to claim 1. Preferred configurations of this gasket are described in the subclaims. Accordingly, the invention relates to a flat gasket and in particular a metallic flat gasket with at least one sealing layer, which has at least one through opening, which is at least on one side is completely surrounded by a self-contained raised sealing surface. The sealing surface consists of a material that is pressure and creep-resistant and not deformable under the loads of the application. It has a height profile which, if necessary with the inclusion of other existing sealing layers, is designed in accordance with the topography of the sealing gap formed between the mating surfaces to be sealed.The topography of the sealing surface is obtainable by embossing the sealing surface in a sealing plate in such a way that the thickness of the sealing plate in the area of the sealing surface is at least partially reduced compared to the initial thickness of the sealing plate. Furthermore, the flat seal has at least one of the following features: a) In the area of the sealing surface there is a support with a thickness which, together with the height of the sealing surface, gives a total thickness which is greater than the initial thickness of the sealing plate from which the sealing surface is formed has been; b) areas of the sealing plate which are located outside the sealing surface and have a thickness of at least the initial thickness of the sealing plate have been completely removed; and c) regions of the sealing plate which are outside the sealing surface and have a thickness of at least the initial thickness of the sealing plate are bent out of the plane of the sealing plate.

The determination of the topography of the sealing gap to be sealed and the transfer of this topography to the raised sealing surface can be carried out as is customary in the prior art. Possibilities are described, for example, in EP 0485693 A1. If, in addition to the sealing layer in which the topographically formed sealing surface is present, further sealing layers are provided in the seal, these are taken into account when forming the topography if they are in the region of a raised sealing surface. It is possible to form the height profile which changes in the circumferential direction exclusively in the sealing layer having the raised sealing surface, while the further sealing layers have a constant thickness in the region of the sealing surface. However, it is equally possible to provide an additional sealing layer in the area adjacent to the raised sealing surface of the sealing surface sealing layer with a height profile. In this case, the overall height profile of all sealing layers in the area of the raised sealing surface corresponds to the topography of the sealing gap to be sealed. The sealing surface can also have a width profile in addition to the height profile. This not only changes the height of the sealing surface in the circumferential direction, but also its width. The flat gasket according to the invention is preferably obtainable by embossing the raised sealing surface in a sealing plate. However, this does not rule out that the flat gasket according to the invention can also be produced by another manufacturing process, for example a material-removing process or a Combination of cutting processes and embossing processes was obtained. The production of the flat gasket according to the invention with the aid of an embossing step, in which the height-profiled sealing surface is embossed while reducing the thickness of the sealing plate, is particularly simple, quick and inexpensive. The embossing process is carried out in a manner known per se using conventional tools. If necessary, the embossing step can be followed by a calibration step for fine adjustment of the height and / or width profile. In addition, in the embossing step, if desired, small raised sealing webs can also be embossed on the sealing surface, as described in WO 97/01722 A1 to improve the micro-sealing.

[0011] The sealing surface can be embossed such that only a part of the sealing surface is reduced in thickness compared to the initial thickness of the sealing plate, while one or more other sections retain the original thickness and thus represent the highest sections of the sealing surface. However, it is preferred to reduce the thickness of the sealing plate in all areas of the sealing surface. The embossing leads to a strain hardening of the sealing material and thus to a higher stability in the embossed area.

After embossing, the sealing plate in the region of the raised sealing surface thus at least partially has a smaller thickness than the initial density of the sealing plate. In this form, the sealing plate cannot be used as a flat gasket, since the non-embossed areas prevent the sealing surface from performing its supporting function. The invention solves this problem in the manner described in points a) to c).

In variant a) a support is placed on the embossed, height-profiled sealing surface, the thickness of which is sufficient to give, together with the height of the sealing surface, a total thickness which is greater than the initial thickness of the sealing plate. The overlay can consist of a coating or a separate part. In order to maintain the stability of the flat seal in the area of the sealing surface, the material is also expediently pressure and creep resistant and not deformable in height. As already described in the case of multi-layer seals, the height profile can be limited to the sealing surface of the embossed sealing layer, or a height profile can be present both in the raised sealing surface and in the support, so that overall a height profile corresponding to the topography of the sealing gap to be sealed results , The height profiles can be produced separately or together, namely, for example, in such a way that the support is placed on the sealing plate in the region of the subsequent sealing surface before the embossing step and is embossed together with the sealing plate. In variant b), the areas which are outside the sealing surface and have a thickness of at least the initial thickness of the sealing plate are completely removed. That is, all those areas of the sealing plate are removed which prevent the previously embossed sealing surface can perform their sealing and support function in the finished flat gasket. These areas are removed preferably by stamping. The through openings of the flat gasket according to the invention are expediently punched at the same time

In variant c) finally areas of the sealing plate, which are located outside the sealing surface and have a thickness of at least the initial thickness of the sealing plate, are bent out of the plane of the sealing plate. This variant is suitable for flat gaskets which are used to seal mating surfaces which have recesses or recesses. The thick areas of the sealing plate, which prevent the sealing function of the embossed sealing surface, are bent into these recesses or recesses and therefore no longer stand in the way of the sealing function of the raised sealing surface.

Variants a) to c) can also be used in combination with one another in a flat gasket. For example, it is possible to use different sealing variants in the area of different through openings. A combination of variants a) and b) is also conceivable, in which the sealing surfaces are provided with supports and, moreover, non-embossed areas of the sealing plate have been removed.

The seals described are available in a simple manner and can in particular be produced without complex material-removing processes. The choice of material for the flat gasket according to the invention and in particular for the position which the height-profiled sealing surface has depends primarily on the type of intended use. Suitable are, for example, pressure-resistant and creep-resistant, non-deformable plastics, ceramics and in particular metallic materials. Basically, all of the materials previously used for the corresponding flat seals can also be used. As already mentioned, the flat gasket according to the invention can have more than one through opening which is surrounded by a raised, topographically formed sealing surface. In the case of variant b) in particular, in which parts of the sealing plate have been removed, it makes sense to connect adjacent surfaces to one another. For this purpose, connecting webs are preferably used, the height of which is less than the initial thickness of the sealing plate with the raised sealing surfaces. These connecting webs are expediently embossed together with the sealing surfaces in order to set a suitable height for them. With through openings lying closely next to one another, sealing surfaces surrounding adjacent openings can share a common section. After punching away the areas of the sealing plate that are not required, a skeletal sealing layer is then obtained. The metallic pads already described in case a) can also be connected to one another via connecting webs or common sections. It is expedient that the connecting webs, which connect the supports to one another, come to rest on the connecting webs for the sealing surfaces. The flat seals according to the invention can be used in the form described above. However, the seals can be used particularly flexibly if they have at least one further sealing layer which is arranged adjacent to the sealing layer having the raised sealing surface. The further sealing layer is preferably a metallic sealing layer. With regard to the outer dimensions of the further sealing layer, it has proven to be expedient if the further sealing layer corresponds at least to the outer circumference of the sealing surface sealing layer. It can be particularly expedient if the further sealing layer protrudes at least in sections over the sealing surface sealing layer. This variant is particularly suitable when different, adjacent parts are to be sealed with one and the same flat seal. Then, for example, only the protruding further sealing layer can be used to seal another part.

In a first possibility, the further sealing layer extends over the adjacent raised sealing surface, for example up to the edge of the through opening enclosed by the sealing surface. In such a case, the further sealing layer has, for example, a basic surface substantially corresponding to the base surface of the sealing surface sealing layer, or it extends beyond the edge thereof. As already mentioned, in this case the superimposition of several sealing layers in the area of the topographically formed sealing surface takes into account the height profile of the sealing surface of this additional sealing layer.

In the second possibility, the second sealing layer has a recess at least in its area opposite the raised sealing surface. In this case, the additional sealing layer does not have to be taken into account when dimensioning the height profile of the raised sealing surface. [0023] The sealing surface sealing layer and further sealing layer are expediently fastened to one another. Any common fastening method is suitable for this, for example clipping, gluing, soldering or welding. The further sealing layer is preferably attached in a region of the sealing surface sealing plate which is outside the sealing surface and is thinned compared to the initial thickness. The dilution is expediently carried out in the stamping step together with the stamping of the sealing surface. The further sealing layer can only be used to adjust a certain thickness of the flat gasket according to the invention and in this case advantageously has a substantially uniform thickness. However, it is preferred if the further sealing layer has additional functional elements and in particular at least one elastic sealing element. This results in the possibility of sealing through openings, which should not be sealed by a raised, topographically formed sealing surface, in a different way. The distribution of these different sealing elements over different sealing layers makes the flat gasket according to the invention particularly flexible and also easy to manufacture. This elastic sealing element can be used to seal areas that are difficult to seal with stable seals. Here is the cylinder head gaskets described above Sealing a chain case or an engine made of different materials. Stable, topographically designed areas of the seal can be used, for example, to seal counter surfaces (sections) which are relatively hard and can be subjected to relatively high screw forces, while softer counter surfaces (sections) or shape changes during operation or greater manufacturing tolerances are subject to sections the elastic areas of the seal according to the invention are sealed.

[0025] To create an elastic sealing element, the further sealing layer can be beaded, for example, the beading being able to have any shape that has been customary to date. Additionally or alternatively, an elastic application can be present in the further sealing layer. Elastomeric materials such as, in particular, elastomeric plastics are suitable for elastic application.

[0026] In addition to the further sealing layer described, further sealing layers can also be present in the flat seal according to the invention. For example, the sealing surface sealing layer can be enclosed on both sides by further sealing layers. Further sealing layers, which extend entirely or only partially over the sealing surface sealing layer, are also possible. Further sealing layers are also conceivable, which extend to the side of the sealing surface sealing layer and are connected, for example, to a further sealing layer projecting laterally beyond the sealing surface sealing layer. The area of application of the flat gasket according to the invention is not particularly limited. A preferred application is in those areas in which the counter-surfaces to be sealed are at least partially strongly bent against each other or in which strong pressure fluctuations occur during use. A preferred application is in the area of engine gaskets such as manifold gaskets and in particular cylinder head gaskets. [0028] If the flat gasket according to the invention is a cylinder head gasket, the at least one through opening surrounded by a raised sealing surface is advantageously a combustion chamber opening, while the through opening surrounded by an elastic sealing element is selected from an oil, water or chain box opening. For example, all combustion chamber openings are each surrounded by a raised sealing surface, while oil and water openings are surrounded by elastic sealing elements which are formed in one or more additional sealing layers. The flat gasket according to the invention is particularly suitable for simultaneously sealing a chain case. With conventional cylinder head gaskets, problems with tightness often occur in the border area between the chain case and the engine block. If chain case and cylinder block openings are to be optimally sealed at the same time, quite complicated seals have hitherto often been required. With the flat gasket according to the invention, these problems can be avoided since the gasket in the area around the combustion openings where large pressure fluctuations occur, are stable and vibrations are practically not transmitted into the seal. At the same time, the separate additional sealing layer with elastic sealing elements enables flexible sealing of the chain case and manufacturing tolerances can be compensated for without any problems.

The seal according to the invention is also extremely suitable as a cylinder head gasket for the Al-Mg engine blocks described. While the core area of the seal is designed to be stable and seals the combustion chamber openings in the hard aluminum core, in the edge area of the seal above the Mg shell there is expediently only at least one further sealing layer with elastic sealing elements. These elastic areas can easily follow the thermally induced changes in the sealing gap in the Mg area and ensure good tightness here. The further sealing layer is preferably attached to the topographic sealing layer in such a way that it is supported only via the Al core and no attachment in the Mg Area of the engine block is required.

The flat gasket according to the invention is also particularly suitable as a cylinder head gasket for sealing so-called open-deck engines. With these engines, there are no intermediate webs in the cylinder block between the outer wall and the cylinder tube. The seal according to the invention is now designed such that, in variant c), the regions bent out of the plane of the sealing surface sealing plate come to rest in the open regions of the engine block. The thicker areas that are bent out no longer impair the sealing function of the embossed areas of the sealing plate that rest on the engine block. In this way, a cylinder head gasket that is very easy to produce can be obtained. In a development of these seals, it is possible to provide at least one bulge facing the engine block side as a compensating bead within the bent-out areas. [0032] The individual sealing layers of a flat gasket according to the invention can be provided with a coating at least on one side and at least in regions. A coating - in contrast to a sealing layer - is to be understood here in the usual way to be an application which, in its entire area, rests on and adheres to the sealing layer to be coated.In addition, a coating will usually have a significantly smaller thickness than the coated sealing layer. The purpose of a coating can be to protect the underlying sealing layer, to improve the physical properties such as sliding friction and to improve the micro-seal. All of the coatings previously suitable for the respective flat gasket can also be used. The coatings known from DE 19941410 A1 are particularly preferred. The invention will be explained in more detail below with reference to a drawing. It shows schematically: Figure 1 is a partial plan view of a first example of a flat gasket according to the invention.

2 shows a plan view of a further example of a flat gasket according to the invention;

3 shows a schematic partial cross section through a preform of a flat gasket according to the invention in the area A-A of FIG. 1;

4 shows a seal made from the preform according to FIG. 3 in cross section along the line A-A;

5 shows a further example of a seal finished from the preform according to FIG. 3, likewise in cross section along the line A-A;

6 shows a further example of a flat gasket according to the invention in cross section along the line A-A of FIG. 1;

7 shows a further example of a flat gasket according to the invention in cross section along the line B-B of FIG. 2;

8 shows the seal according to FIG. 7 in cross section along the line C-C;

FIG. 9 shows another example of a flat gasket according to the invention in the area of line D-D of FIG. 2 in cross section;

10 shows yet another example of a flat gasket according to the invention in cross section along the line D-D of FIG. 2;

11 shows another embodiment of a flat seal according to the invention in a representation corresponding to FIG. 10; 12 shows yet another example of a seal according to the invention in cross section in the area corresponding to FIGS. 9 to 11; 13 shows a cross-sectional illustration along the line B-B of a further embodiment of a flat gasket according to the invention, which is clamped between the engine block and the cylinder head; and

14 shows an alternative embodiment of the seal according to FIG. 13 in the same area, likewise in cross section.

Figures 1 and 2 schematically show partial top views of seals according to the invention using the example of cylinder head gaskets 1. The seals 1 have oil openings 5, water openings 6 and screw openings 7 in addition to combustion chamber openings located inside the seals. In addition, there is an opening 10 for a chain case in the seal according to FIG. 2. Size and distribution of the openings on the Sealing surface are shown here only very schematically and only to show the principle of operation of the seals according to the invention.

Figure 1 shows the top view of a sealing plate 2, while in the seal according to Figure 2 in addition to the sealing plate 2 there is a further sealing plate 11 In the sealing plate 2 located inside the seal are the combustion chamber openings 3 and the screw openings surrounding them. 7 arranged. The sealing plate 11 comprises the oil openings 5, water openings 6 and screw openings 7 and the chain case opening 10 arranged on the outer edge of the seal.

The sealing plates 2 each consist of a pressure-resistant and creep-resistant material that is not deformable under the operating conditions of the cylinder head gaskets. It is preferably metal.

In the sealing layer 2 raised sealing surfaces 4 are formed, which the combustion chamber openings

3 each completely surrounded. The height of the sealing surfaces changes in the circumferential direction around the combustion chamber openings 3. The height profile is designed in accordance with the topography of the sealing gap in the region of the respective combustion chamber opening. In addition to the height profile, the respective sealing surface 4 can also have a change in its width in the circumferential direction. The sealing gap topography is determined as known from the prior art and described, for example, in EP 0485693 A1. As already mentioned there, the raised sealing surfaces 4 preferably grow out of the sealing plate 2 without jumping. The rings labeled 4 therefore only illustrate the approximate position of the apex surfaces of the sealing surfaces 4.

In addition to the combustion chamber openings, the further liquid openings, that is to say oil openings 5 and water openings 6, are also surrounded by sealing devices. For the sake of clarity, these are just as little shown in FIGS. 1 and 2 as sealing devices around the chain box opening and supporting surfaces around the screw openings, which may be present. In the seals according to Figure 1, the entire sealing plate 2 can be topographically formed, so that the oil and water openings are surrounded by height and / or width profiled sealing surfaces, which correspond in their topography to the sealing gap to be sealed. Alternatively, the liquid openings 5 and 6 can be surrounded by elastic sealing devices. The elastic sealing device can be, for example, a screen printing application made of an elastomeric material that has been applied to the sealing plate 2. This is also already described in EP 0485693 A1. In the seals according to Figure 2, the liquid openings 5 and 6 arranged adjacent to the sealing edge 8 and the chain case opening 10 in the sealing plate 11 are also surrounded by elastic sealing elements. In contrast to the sealing plate 2 with the topographically formed sealing surfaces 4, the thickness of the sealing plate 11 is not topographically formed and essentially has have a uniform thickness over their entire surface. The elastic sealing elements in this plate are expediently beads formed in the sealing plate 11 or elastomeric elements applied to the sealing plate 11. Specific examples will be described later.

The topography in the sealing plate 2 is preferably produced in an embossing process. For this purpose, the desired height profile is stamped into a sealing plate with an initial thickness D using a suitable stamping tool, for example as described in EP 0485693 A1. The entire height profile of the sealing plate 2 is expediently stamped in a single stamping step. The material of the sealing plate 2 is deliberately embossed in the areas of the later sealing surfaces 4 and, if appropriate, in further load-bearing areas of the seal that absorb the surface pressures, and its thickness is reduced. Pressed down material is pushed out to the side of the embossed surfaces, so that in these areas the thickness of the embossed sealing plate 2 can be greater than the initial thickness D of the sealing plate. FIG. 3 shows a sealing preform after the embossing step in cross section along the line A-A in FIG. 1.

Figure 3 illustrates that the embossing step is carried out before the through openings are made in the sealing plate 2. The area between two adjacent combustion chamber openings (3 in FIG. 1) is shown, which are connected to one another by a web area 9. Each of the combustion chamber openings 3 is surrounded by a circularly closed sealing surface 4. If the combustion chamber openings 3 are very close together, it is possible for the sealing surfaces 4 to converge into a single sealing surface 4 in the region between the combustion chamber openings 3, so that the web region 9 would then be omitted. As can be seen in Figure 3, the thickness of the sealing surfaces 4, which is designated here by d, is reduced compared to the initial thickness D. The seal preform shown in FIG. 3 cannot be used as a seal after the embossing step. The non-embossed areas with at least the initial thickness D prevent the sealing surfaces 4 from performing their supporting function and from filling the sealing gap which is formed between the engine block and the cylinder head. The various variants according to the invention with which this problem can be avoided are now described below. In the seal according to FIG. 4, supports 12 are placed on both sides of the sealing surfaces 4. The thickness of the supports 12 is dimensioned such that the total thickness d1 in the area of the sealing surfaces 4 is greater than in the areas of the sealing plate 2 which are not embossed down, so that the sealing surfaces 4 with the supports 12 can perform their supporting function and reliably seal the sealing gap to be sealed , The pads 12 consist of a material which, like the material of the sealing plate 2 under the conditions of use of the cylinder head gasket 1, is pressure-resistant and creep-resistant and cannot be deformed in height. These are preferably metallic supports, but ceramic or another suitable material can also be used. In a variant, the supports 12 are attached in a suitable manner on the sealing surfaces 4 as annular supports, for example as stamped metal rings, for example glued, soldered or welded. However, the pads 12 can also be sintered.

The non-embossed areas of the sealing plate 2 in the area of the combustion chamber openings 3 are removed in the seal according to FIG. 4. This is preferably done by means of a stamping step which can be carried out before or after the pads 12 are attached. When the combustion chamber openings are opened, all other openings are expediently punched into the sealing surface, so that only one punching step is required.

FIG. 5 shows a modification of the seal according to FIG. 4. In the latter, the connection area between the combustion chamber openings 3 is not co-embossed in the embossing step and is therefore essentially retained in its original height. The pads 12 placed on the sealing surfaces 4 are each designed as individual rings. In contrast, in the seal according to FIG. 5, the thickness of the connection area between adjacent combustion chamber openings 3 is at least partially embossed, so that an embossed connecting web 9 has been created between adjacent combustion chamber openings, which has a cross-section according to FIG. 3 and a top view of FIG is indicated. Above and below this connecting web 9 in the sealing layer 2, adjacent annular supports 12 are each connected to one another by a narrow connecting web 12 ¹ . Instead of individual annular supports 12, an eyeglass-like support can therefore be used for several adjacent sealing surfaces 4. The reduced number of parts makes handling easier. The seals described in Figures 4 and 5 correspond to variant a) of the invention, in which the production of the height profile of the load-bearing areas and the surface pressure-absorbing areas of the topographic sealing plate is made possible by a simple thickness-reducing stamping-down step by increasing the thickness on the embossed sealing surfaces Edition is applied. In the examples shown, the pads 12 were placed only after the stamping process had been carried out. Alternatively, however, it is also possible to apply the supports 12 to the non-embossed sealing layer before the embossing step and to emboss the supports 12 together with the later sealing surfaces 4. It then depends on the type of sealing plate 2 and the supports 12, in which distribution the height profile is formed between the two layers. Usually, a change in the thickness of the material in the circumferential direction will occur both in the supports 12 and in the sealing surfaces 4 of the sealing plate 2. In contrast, the thickness change in the circumferential direction in the sealing plate is expedient in the case of supports 12 subsequently placed on the sealing layer 2 2 be formed, while the pads 12 have a constant thickness. In principle, however, it is also conceivable for each of the sealing surfaces 4 and the supports 12 to be designed separately with a height profile that changes in the circumferential direction, although this naturally becomes more complex to manufacture.

Figures 6 to 12 describe seals which correspond to variant b) of the invention. The preliminary stage of these seals is again an embossed seal preform, as is shown in detail as an example in FIG. 3 Here, however, the embossed areas of the sealing plate 2 are not built up in their thickness, but rather those areas of the sealing plate are removed which are above the embossed load-bearing areas Project sealing surfaces and hinder their support function. These sealing areas are preferably removed simultaneously with the introduction of the through openings into the sealing plate 2. It is particularly simple if all of the through openings are punched out together with the disruptive, non-embossed areas of the sealing plate 2. It is preferred if the load-bearing sealing surfaces are connected to one another by means of embossed connecting webs, so that after the areas of the sealing plate 2 that are not required are punched away, a skeleton-like sealing structure composed of supporting sealing surfaces and connecting webs remains.

Figure 6 shows a section of such a skeletal structure of the sealing plate 2 in cross section along the connecting line AA in Figure 1. From a preform, as shown in Figure 3, wherein a thinned connecting web 9 is stamped in the connection area between the sealing surfaces 4 If, as indicated by the dashed lines, the through-openings are punched in a punching step and also all non-embossed areas of the seal, which are not raised sealing surfaces and no connecting webs, are punched out. After the stamping step, a skeleton-like structure is therefore obtained which comprises through openings surrounded by profiled sealing surfaces and connecting webs which connect these topographically formed sealing surfaces to one another. In addition, additional supporting sealing skids can be provided, which are equipped with a height profile corresponding to the topography of the sealing gap between the engine block and the cylinder head and which absorb surface pressure when the engine block and the cylinder head are clamped together. Such a sealing skid can for example run along the edge of the seal and is also expediently connected to the remaining elements of the sealing plate 2 via connecting webs. However, it is also possible to dispense with connecting webs between the height-profiled sealing surfaces 4 of the sealing layer 2. This variant is particularly suitable for multi-layer seals. In this case, the embossed raised sealing surfaces are expediently fastened to an additional sealing plate. Figure 7 shows a possible example. A cross section through the seal in the area between adjacent combustion chamber openings 3 is shown again. This can be a cross section along the line BB according to FIG. 2, in which a further seal layer 11 is located adjacent to the seal layer 2 protrudes from the sealing layer 2 on all sides. However, it can just as well be a cross section along the line AA of FIG. 1, a further sealing layer 11 being located below the sealing plate, the outer dimensions of which essentially correspond to the sealing plate 2. In contrast to the seal according to FIG. 6, there is no connecting web 9 in the seal according to FIG. 7 between the adjacent sealing surfaces 4. That is, no connecting web 9 was embossed in the sealing preform according to FIG. 3, but the intermediate area essentially has the original thickness D of the sealing plate 2, as is shown by the solid line in this intermediate area.

The sealing plate 11 in the seal according to FIG. 7 expediently has a constant thickness over its entire surface. Since it extends over the profiled sealing surfaces 4 to the combustion chamber openings 3, its thickness must be taken into account when dimensioning the height profile of the sealing surfaces 4 so that the overall height profile of the sealing surfaces 4 plus the sealing plate 11 corresponds to the topography of the sealing gap in this area , In the case shown, the sealing plate 11 is located on the engine block side and, accordingly, the sealing layer 2 with the embossed sealing surfaces 4 on the cylinder head side. The same applies to the seals shown in the following FIGS. 8 to 12.

FIG. 8 shows the seal according to FIG. 7 in the area towards the sealing edge 8 in cross-section along the line CC of FIG. 2. This example illustrates the combination of a stable, non-deformable sealing area, as is known, for example, from EP 0485693 A1 with a conventional elastic seal of a through opening. In the case shown, the combustion chamber openings 3 are sealed non-elastically with topographically designed sealing surfaces 4, as has already been described in connection with FIG. 7. However, the edge area of the seal 1 is only sealed by elastic sealing elements which are formed in the sealing plate 11. Beads 13, which completely run around the oil openings 5, the water openings 6 and the chain case opening 10, serve as elastic sealing elements. FIG. 8 shows the elastic seal with the aid of a bead 13 which completely surrounds a water opening 6. The bead 13 is round here, but it can just as well be an angular bead or half bead. In addition, a further elastic sealing element is present on the sealing edge 8, namely a half bead 14 which runs around the outer sealing edge. The preferred material of the sealing layer 11 is spring steel. The seal shown is particularly well suited for engines that have a hard inner core and a softer outer jacket. For example, the engine core containing the combustion chamber openings 3 can be made of aluminum, while the outer jacket with the oil openings 5 and water openings 6 consists of magnesium.The very different hardness of these two metals and their different coefficients of thermal expansion make reliable sealing of all through openings with conventional, purely elastic seals difficult on the one hand and purely steadily trained topographic on the other hand, extraordinary. In the former case, at best a very complicated sealing structure leads to satisfactory results with not always optimal sealing of the combustion chamber openings in particular, while in the latter case non-elastic topographic seals lead to an insufficient sealing of the liquid openings at the sealing edge. The main reason is that, on the one hand, due to the low mechanical strength of the magnesium in the edge area, adequate surface pressures cannot be achieved and, on the other hand, the different coefficients of thermal expansion of the metallic materials lead to changes in the sealing gap depending on the temperature, which can be achieved with a non-elastic seal can hardly be compensated.

The multi-layer seals according to the invention with stable and elastic areas solve this problem in an almost ideal manner. The stable, non-deformable sealing surface areas enable reliable sealing of the combustion chamber openings 3, which are subject to high temperatures and pressures, ensure a uniform surface pressure distribution with relatively low screw forces and also prevent vibrations from being transmitted to the edge area of the seal. In the edge regions of the seal, on the other hand, the elastic elements of the sealing plate 11 readily absorb the changes in the sealing gap caused by the strong thermal expansion of the magnesium. The sealing plate 11 is also preferably guided into the stable area of the seal above the harder aluminum core of the engine block. In the case shown, the sealing plate 11 extends up to the edge of the combustion chamber openings 3. As a result, the elastic sealing plate 11 is supported on the hard aluminum core of the engine block, which reduces mechanical stress on the softer magnesium edge. This largely prevents the cylinder head gasket 1 according to the invention from digging into the magnesium casing of the engine block. In addition, the number of fastening screws in the edge area can be greatly reduced, and the clamping pressure need only be low. The sealing of a chain case opening also succeeds with the seal according to the invention in a reliable manner. One problem with the sealing of chain boxes is that, depending on manufacturing tolerances and deviations in the attachment of the chain boxes from engine to engine, different offsets and cracks occur in the sealing surface. These variable jumps in the counter surface to be sealed can practically not be bridged with purely stable seals. However, this is achieved with the seals according to the invention, which combine stable areas with non-stable, elastic areas. Various options for connecting and sealing chain box openings are described in FIGS. 9 to 12. These show cross sections along the line DD in FIG. 2. FIG. 9 shows a simple variant in which the chain box opening 10 is surrounded by a half bead 14 which is formed in the elastic sealing plate 11. The combustion chamber openings 3 are again surrounded by stable, topographically formed sealing surfaces 4. In contrast to that in FIG. 7 However, the seal plate 11 described does not run below the sealing plate 2, so that the latter does not have to be taken into account when dimensioning the height profile of the sealing surface 4 in accordance with the topography of the sealing gap to be sealed. Rather, there is a recess 15 in the sealing plate 2 in the region of the outer edge of the raised sealing surface 4 towards the engine block side, the height of which essentially corresponds to the thickness of the sealing plate 11. The inner edge region of the sealing plate 11 is fastened to the sealing plate 2 in this recess 15

FIG. 10 shows a further development of the area of the seal described in FIG. 9. Here the sealing plate 2 does not end with the raised sealing surface 4, but in addition to the edge region 8 of the seal there is a further raised sealing skid 16. Like the sealing surface 4, this is expediently profiled in height and possibly also in width and adapted to the topography of the sealing gap to be sealed in this area. The sealing skid 16 therefore also absorbs part of the clamping pressure when the cylinder head is attached to the engine block and has a supporting and supporting function. The sealing skid 16 is expediently produced together with the sealing surfaces 4 in one and the same stamping step. In addition, the sealing skid 16 can be fastened to an adjacent sealing surface 4 or another area of the sealing plate 2 via a connecting web 9, which is not shown here. The sealing skid 16 leads on the one hand to a more stable fastening of the elastic sealing plate 11 to the stable area of the seal 1 and on the other hand acts as a stopper for the half bead 14. The sealing skid 16 thus prevents the half bead 14 from being completely flattened when the seal is in operation. This increases the life of the half bead 14.

FIG. 11 shows a section of a cylinder head gasket according to the invention, which essentially corresponds to the gasket according to FIG. 10 with regard to the formation of the raised sealing surface 4, the sealing skid 16 and the attachment of the further gasket layer 11. In addition to this, there is now a connecting web 9 which connects the sealing skid 16 and the sealing surface 4 to one another. The elastic sealing element for sealing the chain case opening 10 here does not consist of a bead, but of an application 17 made of an elastomeric plastic. All elastomers that have previously been used for the elastic sealing of through openings in seals are suitable here. The elastomer 17 is preferably applied to the sealing plate 11 in a screen printing process. FIG. 12 shows a further variant of the chain case seal. In contrast to the variants shown in FIGS. 9 to 11, the sealing plate 11 is again brought up to the edge of the combustion chamber opening 3, so that the thickness of the sealing plate 11 must be taken into account when dimensioning the height profile in the sealing layer 2. The sealing of the chain box opening 10 takes place again with a half bead 14, which, however, in contrast to the seals according to FIGS. 9 and 10, is oriented the other way round, namely from top to bottom in the direction of the chain box opening 10. To compensate for the height, a crank 18 is therefore present in the sealing plate 11 adjacent to the sealing surface 4. The half bead 14 is newly stabilized by a sealing skid 16, which is now arranged on the engine block side of the sealing layer 11. As in the previous examples, the sealing skid 16 is expediently still above the harder aluminum core area of the engine block.

Finally, FIGS. 13 and 14 show seals according to the invention using the example of cylinder head seals according to variant c) of the invention. FIG. 13 shows the seal 1 according to the invention clamped in cross section between an engine block 19 and a cylinder head 22. The bog block 19 is a so-called open-deck engine, which is open to the cylinder head 22 between the outer wall 20 and the cylinder walls 21 Has areas 23. The cylinder head gasket 1 can again be produced from a gasket preform, as is exemplarily shown in FIG. 3. The non-embossed sealing areas in the area of the combustion chamber openings 3, which are located in this preform on the side of the embossed sealing surfaces 4, and the other passage openings of the seal were removed by a stamping step. This leaves non-embossed areas with at least the initial thickness D of the sealing plate 2 outside the stamped through openings, which protrude above the surfaces of the embossed sealing surfaces 4 and impair their support function. According to variant c) of the invention, these higher areas are bent out of the plane of the sealing plate 2. The bending out takes place in such a way that the non-embossed, thick areas come to lie in the openings 23, as can be seen in FIG.

The bending out is facilitated by the fact that the connection areas 24 between embossed sealing surfaces 4 and non-embossed areas of at least the thickness D are reduced to a thickness d2 which is less than the thickness d of the embossed sealing surfaces 4. This thickness reduction is advantageously carried out together with FIG. 14 shows a further development of the seal according to FIG. 13. Here, a compensation bead 25 is already in the stamping process for the sealing surfaces 4 in the area that will later be bent out of the plane of the sealing plate 2 imprinted.

All seals described above can be coated. The coating is expediently present at least where the seals come into contact with the mating surfaces of the engine block and cylinder head to be sealed. The coatings, which are not shown here for the sake of clarity, preferably consist of a coating as described by the applicant in DE 19941410 A1.

Claims

PATENT CLAIMS

1. Flat gasket, in particular metallic flat gasket, with at least one sealing layer, which has at least one through opening, which is completely surrounded at least on one side by a self-contained, raised sealing surface, the sealing surface being made of a pressure- and creep-resistant, non-height-deformable material under the loads of the application Material consists of and has a height profile which essentially corresponds to the topography of the sealing gap formed between the counter surfaces to be sealed and possibly further sealing layers, which is obtainable by embossing the sealing surface into a sealing plate in such a way that the thickness of the sealing plate in the area of the sealing surface is at least is partially reduced compared to the initial thickness of the sealing plate, and it further has at least one of the following features: a) in the area of the sealing surface there is a support with a thickness which, together with the height of the sealing surface, results in a total thickness which is greater than the initial thickness the sealing plate; b) Areas of the sealing plate which are located outside the sealing surface and have a thickness of at least the initial thickness of the sealing plate have been completely removed; and c) areas of the sealing plate which are located outside the sealing surface and have a thickness of at least the initial thickness of the sealing plate are bent out of the plane of the sealing plate.

. Flat gasket according to claim 1, characterized in that it has a plurality of through openings surrounded by sealing surfaces and adjacent sealing surfaces are each connected by at least one connecting web with a height that is less than the initial thickness of the sealing plate

3. Flat gasket according to claim 1 or 2, characterized in that in case a) the support is designed as a separate layer and in particular as a separate metallic layer.

4. Flat gasket according to claim 2 or 3, characterized in that several supports are connected to one another via connecting webs, which come to rest on the connecting webs for the sealing surfaces.

5. Flat gasket according to one of claims 1 to 4, characterized in that it comprises a further, in particular metallic, sealing layer which is arranged adjacent to the sealing layer having the raised sealing surface and in particular corresponds at least to its external dimensions.

6. Flat gasket according to claim 5, characterized in that the further sealing layer extends over the raised sealing surface.

7. Flat gasket according to claim 5, characterized in that the further sealing layer has a recess at least in its area opposite the raised sealing surface.

. Flat gasket according to one of claims 5 to 7, characterized in that the further sealing layer is attached to a thinned area of the sealing plate lying outside the sealing surface.

9. Flat gasket according to one of claims 5 to 8, characterized in that the further sealing layer has at least one elastic sealing element, in particular a bead or an application made of an elastomeric material.

10. Flat gasket according to claim 9, characterized in that the elastic sealing element surrounds a through opening extending through the sealing layers, which is not surrounded by a raised sealing surface.

11. Flat gasket according to one of claims 5 to 10, characterized in that the further sealing layer projects laterally beyond the sealing layer having the raised sealing surface, at least in the region of one side.

12. Flat gasket according to one of claims 1 to 11, namely cylinder head gasket.

13. Flat gasket according to claim 12, characterized in that the at least one through opening surrounded by a raised sealing surface is a combustion chamber opening and the through opening surrounded by an elastic sealing element is selected from an oil, water or chain case opening.

14. Flat gasket according to one of claims 1 to 13, characterized in that at least one of the sealing layers is provided with a coating at least on one side and at least in areas.

5. Flat gasket according to one of claims 5 to 14, namely cylinder head gasket for an open deck engine, characterized in that in case c) the areas bent out of the plane of the sealing plate correspond to open areas of the engine block between a cylinder wall and an outer wall.

16. Flat gasket according to claim 15, characterized in that in the bent out areas there is at least one bulge pointing towards the engine block side.