Untitled record

Combined metal gasket Purely metallic gaskets from one or more layers of sheet metal, preferably for sealing cylinder heads to internal combustion engines, in which closed, single or multiple beads are embossed at the points to be sealed, have been known for some time. The embossed beads have the task to give the solid metal seal to a certain deformability, to improve their elastic properties and to increase by reducing the pressing surface, the sealing pressure. In most cases, the screw passages are enclosed with beads in order to support the seal there and to avoid undesirable stresses in the machine parts to be sealed against each other. Such beaded, purely metallic seals require during installation a relatively high pre-press to adapt to the surface roughness and unevenness of the sealing surfaces and thus to achieve a reliable seal. This high pre-pressure is, for example, to cylinder head gaskets, only at the compression chamber passages in a reasonable proportion to the long-term operational sealing pressure, since only at these locations is to seal against high pressures at higher temperatures. At the liquid passages is only to seal against weaker pressures at relatively low temperatures, so that there a lower operating pressure would be possible.

Since, however, high prepressing can not be dispensed with in such beaded metal seals even at these points, high contact forces are required for successful sealing, ie correspondingly large screw cross sections, favorable screw distribution and a particularly rigid design of the engine components associated with the sealing surface.

In the arrangement according to the invention, the above-mentioned defects are avoided. The .metallische seal plate of one or more layers of sheet metal is deformed only by the annular ring, embossed, single or multiple beads only at the necessary locations, so for example in cylinder head gaskets on the compression space passages and screw holes. At all other sealing points, the metal sheet remains flat, the sealed point itself is reinforced on one or both sides by a more or less narrow, annular soft material support, the soft material is selected according to the expected at this point stresses. For the inventive concept, it is immaterial whether the soft material, such as rubber, cork, Itmaterial and plastics of all kinds; glued as edging on both sides, vulcanized or otherwise secured or whether it is pressed in as a molded part or whether, applied as a liquid or paste-like mass, takes on the desired elastic shape by drying or hardening. Although the bead embossing on the screw holes does not serve as a seal, it is expedient for supporting the sealing surfaces in the above-mentioned sense. If appropriate, further such support beads can also be arranged at other locations on the surface. In certain cases, it is expedient to improve the metallic surface by a suitable finish. It may be necessary to also place beads on individual fluid passages where higher pressures prevail, such as at pressure oil passages, if no suitable soft material is found, or to support the soft material with a metal skirt.

A seal constructed in this way reduces the purely metallic sealing surface to the necessary minimum dimension, while at all other sealing points, a soft material which requires only small pre-compression takes over the sealing. This makes it possible to use embossed metal seals also in engines where the existing screw ratios would preclude the use of a purely metallic caulking seal. If the screw ratios are sufficient, the described combined metal gasket at the compression space passage provides increased safety against leakage.

Fig. 2 shows the example of a combined metal gasket in which the metallic gasket plate a is deformed at the compression space passages b and at the screw holes c by a double bead, while the fluid passages d are reinforced by soft material pads; Fig. 2 shows the cross section through this combined metal gasket; Fig. 3 to 8 show exemplary embodiments of the arrangement of the soft material supports on combined metal seals with one or three layers of sheet metal; Fig. 3 shows soft coverings that are glued or vulcanised onto the metal; Fig. Q. Fig. 12 shows soft pads adhered or vulcanized to perforations of the carrier sheet suitably arranged around the point of sealing; Fig. 5 shows soft material overlays which protrude inwards and are glued or vulcanised together there; Illustration 6 shows soft pads, which have been applied in liquid or pasty form on the carrier sheet; Fig.7 shows a soft molded part, which encloses the carrier sheet on both sides; Fig. 8 shows a soft molded part with one-sided support; The metallic carrier also has on both sides a surface finish e.