Abstract
A flat gasket, as used for example as a cylinder head gasket in internal combustion engines may have a first layer and at least one through-opening which extends through all the layers of the flat gasket. The first layer may have a filling channel which extends in the layer plane to the through-opening in the first layer. A circumferential edge of the through-opening in the first layer may have a moulded-on seal which contains or is made of an elastomer and which runs around the through-opening and extends into the filling channel. In the uncompressed state of the flat gasket, the elastomeric filling of the filling channel may have in a region of the filling channel adjacent to the circumferential edge of the through-opening in the first layer, a region that is thickened perpendicular to the layer plane of the first layer.
Claims
1-16. (canceled)
17. A flat gasket having a first layer and at least one through-opening which extends through all the layers of the flat gasket, wherein the first layer has a filling channel which extends in the layer plane to the through-opening in the first, wherein the circumferential edge of the through-opening in the first layer has a moulded-on seal which contains or is made of an elastomer and which runs around the through-opening and extends into the filling channel, wherein in an uncompressed state of the flat gasket the elastomeric filling of the filling channel has, in a region of the filling channel adjacent to the circumferential edge of the through-opening in the first layer a region that is thickened perpendicular to the layer plane of the first layer.
18. The flat gasket according to claim 17, wherein, in the uncompressed state of the flat gasket, the maximum or average thickness of the elastomer in the thickened region is 10 to 50% greater than the sum of the thicknesses of all the layers which have the filling channel in regions of the flat gasket adjacent to the thickened region.
19. The flat gasket according to claim 17, wherein, in the uncompressed state of the flat gasket, a maximum extension of the thickened region on a straight line that is parallel to a tangent at the edge of the through-opening located at the end of the filling channel, at half a height of the protrusion of the thickened region, is at least 0.5 mm.
20. The flat gasket according to claim 17 wherein, in the uncompressed state of the flat gasket, a maximum extension of the thickened region on a straight line that is parallel to a tangent at the edge of the through-opening located at the end of the filling channel, at half a height of the protrusion of the thickened region, is at least , of an extension of the filling channel on the same straight line.
21. The flat gasket according to claim 19, wherein in the uncompressed state of the flat gasket, an extension of the thickened region in the radial direction to the through-opening is between 0.8 and 5 times the extension of the thickened region in a straight line that is parallel to a tangent at the edge of the through-opening located at the end of the filling channel, at half the height of the protrusion of the thickened region.
22. The flat gasket according to claim 21, wherein the extension of the thickened region is the maximum extension or the extension at the middle of the thickened region relative to a direction perpendicular to this extension.
23. The flat gasket according to claim 19, wherein said height of the protrusion is the protrusion of the thickened region beyond the outer surface of the outermost layer adjacent to the protrusion, determined perpendicular to the direction of extension of the filling channel and perpendicular to the layer plane of the first layer.
24. The flat gasket according to claim 17, wherein in the uncompressed state of the flat gasket, the maximum thickness of the elastomer in the thickened region is 10% greater than the thickness of the elastomer in regions of the filling channel adjacent to the thickened region, including the smallest thickness of the elastomer between the thickened region and the moulded-on seal along the through-opening.
25. The flat gasket according to claim 17, wherein in the uncompressed state of the flat gasket, a maximum thickness of the elastomer in the thickened region is greater than the sum of the thicknesses of all the layers, or of all the layers in which the filling channel is formed, in regions of the flat gasket adjacent to the thickened region.
26. The flat gasket according to claim 17, wherein in the uncompressed state of the flat gasket, a thickness of the elastomer in the thickened region is smaller than the thickness of the elastomer in the moulded-on seal along the through-opening.
27. The flat gasket according to claim 17, wherein in the uncompressed state of the flat gasket, the ratio of a distance of the thickened region from an edge of a moulded-on seal pointing towards the through-opening to a width of the moulded-on seal along the through-opening is 1.1 to 5, the distance being the smallest distance between a region of the moulded-on seal along the through-opening that protrudes beyond the surface of the first layer in the uncompressed state and a region of the thickened region that protrudes beyond the surface of the first layer in the uncompressed state.
28. The flat gasket according to claim 17, wherein the filling channel has a narrowing, in which the thickened region is arranged.
29. The flat gasket according to claim 17, wherein in that the filling channel has a web which extends in the layer plane of the first layer and which extends between the two sides of the filling channel.
30. The flat gasket according to claim 17, wherein the web is attached only at one side to one of the sides of the filling channel, to provide a free end of the web.
31. The flat gasket according to claim 30, wherein the web is arranged such that the elastomer in the thickened region at least partially or completely surrounds the web.
Description
[0027] In the figures:
[0028] FIG. 1 shows a flat gasket according to the invention;
[0029] FIG. 2 shows a flat gasket according to the prior art; and
[0030] FIGS. 3-7 show examples of flat gaskets according to the invention in the portion around the transition between the filling channel and the through-opening to be sealed.
[0031] FIG. 1 shows a portion of a cylinder head gasket 1 in plan view. The flat gasket 1 is single-layered, comprising a first layer 2. Said layer 2 has a plurality of media through-openings, inter alia combustion chamber openings 5a, 5b, media through-openings 6a-6f, and a plurality of through-openings (not further denoted) for fastening means. Said additional media through-openings 6a-6f are, for example, through-openings for cooling water or engine oil between a cylinder head and a crankcase of an internal combustion engine.
[0032] The through-openings 6a-6f are connected to filling channels 7a-7d, wherein the filling channels for the media openings 6a and 6b, and respectively 6c and 6d, are connected to one another. Each of the filling channels ends in a cutout 15a-15d which serves as a filling opening for an elastomer when manufacturing the flat gasket 1.
[0033] FIG. 1 shows the flat gasket 1 in the finished state, in which the circumferential edges of the media through-opening 6a-6f are each surrounded by an elastomeric sealing lip 9a-9f. In addition, the filling channels 7a-7d and the filling openings 15a-15d are filled with the same elastomer 8 from which the sealing lips 9a-9d are made.
[0034] FIG. 2 shows in sub-figures A to C a portion from the transition between a filling channel 7 and a through-opening 6 of a flat gasket from the prior art. FIG. 2A shows a cross-section in the x-z plane. The filling channel 7 has an elastomeric filling 8, which has a smaller thickness than the layer 2. The elastomeric filling 8 then becomes thicker on the side of the circumferential edge of the layer 2 facing towards the through-opening 6, so as to form a sealing lip 9.
[0035] FIG. 2B shows a plan view of the same region of the first layer 2 of the flat gasket 1 in the uncompressed state. In this state, the width of the sealing lip 9 (in the x-y plane) running around the through-opening 6 is constant as seen in plan view. The width of the sealing lip 9 in the x-y plane does not change even at the transition to the elastomeric filling 8 in the filling channel 7.
[0036] FIG. 2C shows the same portion as FIG. 2B, but now after the flat gasket 1 has been compressed between two counterpart components. FIG. 2C therefore shows the installed, compressed flat gasket 1 without the counterpart components actually required for the compression. Due to the compression of the sealing lip 9, the latter is displaced into the filling channel 7 so that the circumferential edge 12 of the sealing lip 9 has a concave indentation 10. As a result, the sealing behaviour of the sealing lip 9 adjacent to the filling channel 7 differs from the sealing behaviour of the sealing lip 9 in those regions in which the sealing lip 9 is supported by the circumferential edge 3 of the layer 2.
[0037] FIG. 3 shows a flat gasket 1 according to the present invention in the portion around the region in which the filling channel 7 opens into the through-opening 6.
[0038] The flat gasket shown in FIG. 3 is configured like that shown in FIG. 2, but in the filling channel the elastomeric filling has a thickening 11 adjacent to the sealing lip 9. FIG. 3A shows a plan view of this thickening 11, FIG. 3B shows a cross-sectional view of the thickening 11 in the x-z plane, and FIG. 3C shows a portion of this region of the thickening in the x-z plane. The width of the thickening here is B.sub.D, and the length thereof is B.sub.R. The length B.sub.R is determined in the direction of extension of the filling channel 7, and the width B.sub.D is determined transversely to the direction of extension of the filling channel 7. The width of the filling channel is denoted B.sub.K, the smallest distance between the circumferential edge 12 of the sealing lip 9 and the thickened region 11 is denoted B.sub.A, and the width of the sealing lip 9 is denoted B.sub.9. The length B.sub.R and the width B.sub.D of the thickening 11 is determined here between the points at which the thickening 11 in the uncompressed state protrudes beyond the layer 2 of the flat gasket 1. The height H11 of the protrusion 11 of the thickening 11 is determined relative to the surface of the layer 2. In the present flat gasket shown in FIG. 3, B.sub.A=1.95 mm, B.sub.D=1.5 mm, B.sub.R=2 mm, B.sub.K=4 mm, B.sub.9=1.7 mm and H.sub.11=0.15 mm. In the case of multiple layers, the heights would be determined in each case relative to the surface of the outermost layer.
[0039] FIG. 4 shows a further inventive flat gasket according to the present invention. This is configured like the flat gasket shown in FIG. 3. In addition thereto, a web 14 is formed between the edges of the filling channel 7 that are laterally adjacent in the x-y layer plane, said web extending in the layer plane of the layer 2 between said two edges and being extended in one piece therefrom and having a reduced thickness. The web 14 may be made for example (in particular by stamping and embossing) from the material of the layer 2 at the time of producing the layer 2. The web 14 has a width, in the direction of extension of the filling channel 7, which is somewhat greater than the length of the thickening 11. The web 14 is arranged such that it extends in a direction parallel to the sealing lip 9, starting from the middle of the thickening 11 located in the direction of extension of the filling channel 7 and ending in the continuation of the circumferential edge of the layer 2 around the through-opening 6. The elastomeric compound 8 in the filling channel 7 is supported by this web 14 so that the combination of the web 14 and the thickening 11 of the elastomeric compound together prevent the sealing lip 9 from escaping in the direction of the filling channel 7 upon being compressed.
[0040] FIG. 5 shows a further flat gasket 1 according to the invention, similar to that in FIG. 3. In a manner differing from the embodiment in FIG. 3, the filling channel 7 has a narrowing 13, in which the thickening 11 is arranged in this example. By virtue of this narrowing 13, the escape space for the thickened region 11 is reduced and the thickened region 11 can thus serve even better as a support for the circumferential sealing lip 9.
[0041] FIG. 6 shows a further embodiment of the flat gasket 1 according to the invention, which is configured like that in FIG. 3. The embodiment shown in FIG. 6 additionally has the web 14 of the embodiment in FIG. 4 and the narrowing 13 of the embodiment in FIG. 5, the web 14 also being arranged in the narrowing 13.
[0042] FIG. 7 shows, in sub-figures A, B and C, three further embodiments in cross-section through a region adjacent to the point at which the filling channel 7 transitions into the through-opening 6. In the illustrated cross-sections, Fig. A shows a single-layer gasket having a first layer 2 which has a circumferential elastomeric seal 9 of radial width B.sub.P. The width B.sub.P is determined here over the region in which the seal 9 protrudes beyond the surfaces of the first layer 2 in the uncompressed state. The edge 12 of the moulded-on seal 9 that points towards the through-opening 6 is rounded. As for the thickened region, the height can be determined as the height H.sub.9 of the region 9 of the seal 9 that protrudes beyond the metal layers, here beyond the uppermost metal layer 4b.
[0043] Sub-figure 7B shows a three-layer gasket having a first layer 2 as carrier layer and in each case a thinner, adjacent sealing layer 4a and 4b. The elastomeric seal 9 has a constriction between the layer 2 and the edge 12 thereof, so that displacement spaces are available for the elastomeric compound 8 when the flat gasket 1 is compressed. The width B.sub.P of the elastomeric seal 9 is determined here between the edge of the first layer 3 and the point on the edge 12 of the elastomeric seal 9 at which the thickness of the elastomeric seal 9 is equal to the total thickness of the layers 2, 4a and 4b of the flat gasket 1.
[0044] FIG. 7C likewise shows a three-layer flat gasket having a first carrier layer 2 and adjacent further thinner layers 4a and 4b as further functional layers. Here, the layer 2 protrudes, in the direction of the through-opening 6, beyond the circumferential edges of the layers 4a and 4b running around the through-opening 6. This makes it possible for the elastomeric seal 9 not just to be moulded onto the circumferential edge of the layer 2 around the through-opening 6, but instead the elastomeric compound 2 can be injected around this circumferential edge 3 of the layer 2 such that it also runs partially onto the surfaces thereof and thus improves the bonding of the elastomeric seal 9 to the layer 2. Here, too, the width B.sub.P is measured from the edge of the layer 3, that is to say from the steel shoulder.
