FR2886364A1 - Flat metal gasket e.g. for i.c. engine cylinder head and exhaust manifold has connecting portions between seal sections made with elastically deformable zones - Google Patents

Abstract

The gasket, comprising at least two seal sections (31, 33, 35, 37) designed to be positioned between two components (10, 20) such as an i.c. engine cylinder head and exhaust manifold, has the connecting portions (32, 34, 36) between the seal sections made with at least one elastically-deformable zone (95, 96, 97) formed by corrugations. The seal sections have holes (81, 81A, 82, 82A, 83, 83A, 84, 84A) to receive centering studs (51, 51A, 52, 52A, 53, 53A, 54, 54A) on one of the two joined components.

Description

TECHNICAL FIELD TO WHICH THE INVENTION REFERS

  The present invention generally relates to metal flat gaskets.

  The invention relates more particularly to a flat metal gasket comprising at least two sealing parts intended to be positioned between two parts to be assembled and at least one connecting portion between the sealing parts.

  It also relates to an assembly comprising two parts to be assembled with each other, namely a first part comprising at least four centering elements and a second part provided with at least four housings intended to receive the centering elements, and a flat metal joint ensuring the connection between the two parts.

  The invention finds a particularly advantageous application in the production of a flat seal ensuring the sealing between two parts of a motor vehicle engine such as an exhaust manifold and a cylinder head of a motor.

BACKGROUND

  The metal flat seals are blades intended to be interposed between two flat surfaces to be assembled in order to seal between these two surfaces by filling their irregularities. These metal flat gaskets comprise positioning openings adapted to receive centering studs to position them precisely on the surfaces to be assembled.

  In motor vehicle engines, in order to ensure the seal at the junction between exhaust ducts of the engine cylinder head and ducts of the exhaust manifold inlet, it is necessary to provide sealing parts around of each conduit. Each duct at the inlet of the collector is surrounded by a flange.

  A single one-piece seal is generally used comprising as many sealing parts as ducts, and between each sealing portion of the seal 30 a rigid connecting portion.

  The exit face of the exhaust ducts of the cylinder head has centering elements such as studs and collector flanges have holes opening to receive these studs. The openings 2886364 2 positioning of the flat gasket are arranged vis-à-vis the studs of the cylinder head and holes opening the collector flanges.

  For mounting this seal between the outlet face of the exhaust ducts of the cylinder head and the exhaust manifold, the connecting portions being rigid, it is possible to center only one sealing portion of the flat gasket on the cylinder head. Thus, such a seal generally has a centering hole on a sealing portion near the center of the flat seal, as well as an oblong hole in alignment with the centering hole on one of the extreme seal portions of the seal. flat to prevent rotation of the flat gasket around the center point. In order for the flat gasket to be mounted on the cylinder head, it is then necessary for the other holes on the sealing portions to have a larger diameter than the diameter of the studs passing therethrough.

  In operation, the cylinder head, the gasket and the exhaust manifold do not expand in the same way. There is then a sliding of each flange of the manifold on the flat gasket and a sliding of the flat gasket on the cylinder head. These slips cause shearing of the flat gasket. As a result, not only does the flat gasket wear out quickly, but also the sealing portions of the flat gasket are positioned in a configuration that no longer provides a seal around the ducts.

  It is known to put a lubricating product between the sealing portions of the flat gasket and the flanges of the exhaust manifold, but the shear stresses on the flat gasket are still very important.

  It is also possible to use a flat gasket for each pipe, each flat gasket being independent of each other. However, the cost of production and assembly resulting from the use of several flat gaskets is high.

  OBJECT OF THE INVENTION In order to overcome the drawbacks of the state of the art mentioned above, the present invention proposes a new flat gasket having a better service life and which remains correctly positioned with respect to the surfaces of said parts to be sealed which are liable to move relative to each other.

  To this end, it is proposed according to the invention a flat metal seal comprising at least two sealing parts intended to be positioned between two parts to be assembled and at least one connecting portion between the sealing parts, in which each connecting part comprises at least one elastically deformable zone.

  Thanks to the use of a flat gasket according to the invention, when the two parts, between which the sealing is effected, move relative to each other, the tensile and compressive stresses exerted by a part sealing on another seal portion of the seal are absorbed by the elastically deformable region of the connecting portion. The sealing portions of the flat gasket then move relative to one or the other of said parts independently of one another, which reduces the wear of the flat gasket according to the invention.

  According to another advantageous characteristic of the flat gasket according to the invention, each elastically deformable zone is formed by corrugations of the connecting part.

  According to another advantageous characteristic of the flat gasket according to the invention, said corrugations extend along the length of the connecting part.

  Thus, the accordion-like corrugated portions of the connecting portions may be compressed or decompressed to absorb tensile or compressive stresses to the sealing portions.

  According to another advantageous characteristic of the flat gasket according to the invention, each sealing portion comprises a first opening intended to receive a cylindrical centering element, belonging to one of said parts, of diameter adjusted to the diameter of said element.

  According to another advantageous characteristic of the flat gasket according to the invention, each sealing portion comprises a second oblong opening extending towards the first opening, the first opening and the second oblong opening being positioned on either side of the opening. a central opening of exhaust gas passage.

  Advantageously, each elastically deformable connection portion of the flat gasket according to the invention makes the two adjacent sealing parts independent of one another. The flat gasket is then no longer subject to the tolerances for mounting the sealing parts relative to each other. In particular, it is possible to center each sealing portion on the first piece to be sealed.

  The sealing portions of the flat gasket become integral with said first part independently of one another and they can follow the movements thereof. In particular, the flat gasket can follow the movements of the first part, without undergoing excessive tensile or compressive stresses, and its sealing portions remain correctly positioned on the surfaces of the two parts to be sealed.

  The invention also relates to an assembly comprising two parts to be assembled with each other, namely a first part comprising at least four centering elements and a second part provided with at least four housings intended to receive the elements of centering, the assembly comprising a flat metal gasket as described above ensuring the connection between the two parts, the first and second openings of each sealing portion are intended to be traversed by said centering elements.

  According to another characteristic of the assembly according to the invention, the first piece, the second piece and the flat gasket are made of different materials.

  According to another advantageous characteristic of the assembly according to the invention, it comprises a lubricant product between the second part and the sealing parts of the flat gasket.

  According to another advantageous characteristic of the assembly according to the invention, it comprises the superposition of several flat seals as described above.

  According to another advantageous characteristic of the assembly according to the invention, the first part comprises an internal combustion engine cylinder head and the second part comprises an exhaust manifold of an internal combustion engine.

  DETAILED DESCRIPTION OF AN EXEMPLARY EMBODIMENT

  The following description with reference to the accompanying drawings given as non-limiting examples, will make it clear what the invention is and how it can be achieved.

  In the accompanying drawings: FIG. 1 is an exploded perspective view of an assembly comprising a cylinder head, an exhaust manifold and a flat gasket according to the invention; FIG. 2 is a view along section A-A of part of the assembly of FIG. 1 when cold; FIG. 3 is a view along section A-A of part of the assembly of FIG. 1 while hot; In Figure 1, there is shown schematically an assembly of a motor vehicle comprising a cylinder head 10, an exhaust manifold 20 and a flat metal gasket ensuring the connection between the cylinder head 10 and the exhaust manifold 20.

  The cylinder head 10 comprises four ducts 11, 12, 13, 14 intended to conduct exhaust gases to four other ducts 21, 22, 23, 24 at the inlet of the exhaust manifold.

  The ducts 11, 12, 13, 14 at the outlet of the cylinder head 10 each open on a flat surface 41, 42, 43, 44 of the cylinder head 10. The ducts 21, 22, 23, 24 at the inlet of the exhaust manifold are each surrounded by a flange 61,62,63,64 having a flat surface 71,72,73,74 vis-à-vis the flat surfaces 41,42,43,44 of the cylinder head 10.

  As shown in FIG. 1, the flat gasket 30 comprises, on the one hand, four sealing portions 31, 33, 35, 37, intended to be positioned between the flat surfaces 41, 42, 43, 44 of the cylinder head 10. and the flat surfaces 71, 72, 73, 74 of the flanges 61, 62, 63, 64 of the manifold 20 and, on the other hand, the connecting portions 32, 34, 36 connecting the sealing portions 31, 33, 35,37 between them.

  Each sealing portion 31,33,35,37 comprises a central opening 91, 92,93,94 of exhaust gas passage adapted to come during assembly of the flat gasket 30 facing one hand, the mouth of the duct 11,12, 13,14 corresponding to the cylinder head 10 and, on the other hand, to the mouth of the duct 21,22,23,24 corresponding to the manifold 20.

  To position the flat gasket 30 between the cylinder head 10 and the manifold 20, the cylinder head 10 comprises centering elements or studs 51, 52, 53, 54, 51A, 52A, 53A, 54A intended to pass through the positioning openings 81, 82 83,84,81A, 82A, 83A, 84A made on the sealing portions of the flat gasket 30, and through holes 85,85A, 86,86A, 87,8A, 88,88A made in the flanges 61,62 , 63,64 of the manifold 20. A nut (not shown) is screwed onto each stud 51,51A, 52,52A, 53,53A, 54,54A behind the corresponding flange 61,62,63,64.

  The studs 51,52,53,54,51A, 52A, 53A, 54A are arranged in pairs on each flat surface 41,42,43,44 of the cylinder head 10 on either side of the mouth of the conduit 11 , 12,13,14 corresponding. Similarly, the holes opening 85,85A, 86,86A, 87,87A, 88,88A are arranged in pairs on each flat surface 71,72,73,74 of the flanges 61,62,63,64 of parts and other of the mouth of the conduit 21,22,23,24 corresponding.

  In known manner, the through hole 86 of the flange 62 of the exhaust manifold 20 is a circular centering hole so that the manifold 20 is integral with the yoke 10 at a point. In addition, the through hole 88 in the flange 64 located at one of the two ends of the manifold 20 is an oblong hole to block the rotation of the manifold 20 around the centering hole 86. The other holes 85,85A, 86A, 87 , 87A, 88A are circular holes of diameter greater than the diameter of the studs so that the flanges 61, 62, 63, 64 of the exhaust manifold 20 can expand freely.

  Advantageously, according to the invention, each connecting portion 32, 34, 36 of the flat gasket 30 comprises at least one elastically deformable zone 95, 96, 97. Each elastically deformable zone 95, 96, 97 is formed by corrugations which extend along the length of the connecting portion 32, 34,36.

  Here, each sealing portion 31,33,35,37 comprises a first opening 81,82,83,84, called a centering hole, intended to receive the studs 51,52,53,54, of diameter adjusted to the diameter of the corresponding stud. In addition each sealing portion 31, 33, 35, 37 comprises a second oblong opening 81A, 82A, 83A, 84A, called an oblong hole, intended to receive the studs 51A, 52A, 53A, 54A and extending in the direction of the first opening 81,82,83,84 to block the corresponding sealing portion in rotation. In this way, each sealing portion 31, 33, 35, 37 of the flat gasket 30 is secured to the cylinder head 10.

  Each sealing portion 31,33,35,37 of the flat gasket 30 also comprises a rib 75,76,77,78 obtained by stamping. This rib 75, 76, 77, 78 makes it possible to fill an opening between the joint planes, to maintain a good seal between the cylinder head 10 and the manifold 20. This rib 75, 76, 77, 78 of the sealing portion 31 33,35,37 of the flat gasket 30 has a certain height. When it is going to tighten the manifold on the cylinder head 10,20, a pressure line is created on the flat gasket 30, around this rib 95,96,97,98, which guarantees the seal 31,33,35 37.

  The connection portions 32, 34, 36 of the flat gasket 30 are free from the collector 20 and the cylinder head 10. For the cylinder head 10, this freedom of support of the connecting parts 32, 34, 36 is obtained. by a recessed position of the parts of the yoke 10 vis-à-vis the connecting portions 32,34,36 with respect to the surfaces 41,42,43,44 of the yoke 10 around the ducts 11,12,13, 14,21,22,23,24. For the manifold 20, this freedom of support of the connecting portions 32, 34, 36 is obtained by the separation of the flanges 61, 62, 63, 64.

  In operation, the expansions of the cylinder head 10, the manifold 20 and the flat gasket 30 are mainly along their length, that is to say in the direction X in the drawings of FIGS. 1, 2 and 3. The cylinder head 10 expands weakly. In FIG. 3, the displacement of the yoke 10 due to this expansion is represented by the displacement arrows M and N. The exhaust manifold 20 and in particular the flanges 61, 62, 63, 64 are expanded more significantly than the cylinder head 10 which gives rise to a significant displacement of the manifold 20 as shown by the displacement arrows I and J in FIG.

  Finally, the oblong hole 81A, 82A, 83A, 84A of each sealing portion 31,33, 35,37 and the flexible connecting portion 32,34,36 allow each sealing portion 31,33,35,37 to expand freely in relation to each other. Here, as represented by the arrows K and L in the diagram of FIG. 3, the displacement of the flat gasket 30 substantially follows that of the cylinder head 10 thanks to the studs 51, 52.

  The tensile and compressive stresses, resulting from the displacement of the yoke 10 and the expansion of the flat gasket 30, exerted by a sealing portion 31, 33, 35, 37 on another sealing portion 31, 33, 35 37 are absorbed by the corrugations of the elastically deformable zone 95, 96, 97 of the connecting portion 32, 34, 36. The accordion-like corrugated portions 95,96,97 compress and decompose to absorb the tensile or compressive stresses experienced by the sealing portions 31,33,35,37. The sealing portions 31, 33, 35, 37 of the flat seal 30 then move relative to the exhaust manifold independently of one another.

  In addition, between a cold position shown in FIG. 2 and a hot position shown in FIG. 3, each non-centered flange 61, 43, 64 with respect to the yoke 10 rubs against the flat gasket 30. The flat gasket 30 being retained by the yoke 10 which it is integral is not then driven by the manifold 20 and the friction on either side of the surfaces of the sealing portions 31, 33, 35, 37 of the flat gasket 30 are reduced. Thus the shear stresses on the sealing portions 31, 33, 35, 37 of the flat gasket 30 are greatly reduced and the sealing portions 31, 33, 35, 37 remain in place around the ducts 11, 12, 13, 14,21,22,23,24.

  To reduce the wear of the seal, it can be provided to put a lubricant between the flat surfaces of the flanges of the manifold and the sealing portions of the flat gasket. The lubricant product then makes it possible to limit the friction caused by displacements of the collector with respect to the flat gasket.

  The present invention is not limited to the embodiments described and shown, but the skilled person will be able to make any variant within his mind.

  Alternatively, it may be advantageous to use flat gaskets according to the invention to form a multi-leaf joint, that is to say a seal consisting of the superposition of several joints. Such a seal is used when the opening between the two joint planes is not filled by a single seal. Thanks to the centering of each seal according to the invention, not only the multi-leaf seal no longer slides with respect to the cylinder head, but also, the various joints constituting the multi-sheet seal no longer slide relative to each other.

Claims (10)

  1. Flat gasket (30) comprising at least two sealing parts (31,33,35,37) intended to be positioned between two parts (10,20) to be assembled and at least one connecting part (32,34). , 36) between the sealing portions (31, 33, 35, 37), characterized in that each connecting portion (32, 34, 36) comprises at least one elastically deformable zone (95, 96, 97).   2. flat gasket (30) metal according to claim 1, characterized in that each elastically deformable zone (95,96,97) is formed by undulations of the connecting portion (32,34,36).   3. Flat gasket (30) metal according to the preceding claim, characterized in that said corrugations extend along the length of the connecting portion (32,34,36).   4. Flat gasket (30) according to one of the preceding claims, characterized in that each sealing portion (31,33,35,37) comprises a first opening (81,82,83,84) for receiving a cylindrical centering element (51,52,53,54) belonging to one of said pieces (10), of diameter adjusted to the diameter of said element.   5. Flat gasket (30) according to claim 4, characterized in that each sealing portion (31,33,35,37) comprises a second opening (81A, 82A, 83A, 84A) oblong extending in the direction of the first opening (81,82,83,84), the first opening and the second oblong opening (81,82,83,84,81A, 82A, 83A, 84A) being positioned on either side of a central opening of exhaust gas passage (91,92,93,94).   An assembly which comprises two pieces (10, 20) to be joined together, namely a first piece (10) comprising at least four centering elements (51, 51A, 52, 52A, 53, 53A, 54, 54A) and a second part (20) provided with at least four housings (85,85A, 86,86A, 87,87A, 88,88) for receiving the centering elements (51,51A, 52,52A , 53,53A, 54,54A), characterized in that it comprises a flat gasket (30) according to claims 4 and 5 ensuring the connection between the two parts (10, 20), the first and the second opening (81,82,83,84,81A, 82A, 83A, 84A) of each sealing portion (31,33,35,37) are intended to be traversed by said centering elements (51,51A, 52,52A , 53,53A, 54,54A).   7. The assembly of claim 6, characterized in that the first part (10), the second part (20) and the flat gasket (30) are of different materials.   8. Assembly according to one of claims 6 or 7, characterized in that it comprises a lubricant between the second part (20) and the sealing parts (31,33,35,37) of the seal (30). .   9. Assembly according to one of claims 6 to 8, characterized in that it comprises the superposition of several flat seals (30).   10. Assembly according to one of claims 6 to 9, characterized in that the first part (10) comprises a cylinder head (10) of the internal combustion engine and the second part (20) comprises an exhaust manifold (20). of internal combustion engine.