FR2886363A1 - FLAT METAL JOINT HAVING FRANGIBLE LINK PARTS - Google Patents

Abstract

The present invention relates to a 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 parts.According to the invention, each connecting portion has at least one breakable zone (95,96,97).

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 seal between two parts of a motor vehicle engine such as an exhaust manifold and a block exhaust head -cylinder.

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 leaktightness at the junction between the ducts of the cylinder block exhaust cylinder and the ducts of the exhaust manifold inlet, it is necessary to provide parts of sealing around each duct. 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 cylinder block's exhaust cylinder head has centering elements such as dowels and the collector flanges have holes opening to receive these studs. The positioning openings of the flat gasket are arranged vis-à-vis the studs of the cylinder head and holes opening from the flanges of the manifold.

  In operation, the exhaust cylinder head, the flat 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 seal and a sliding of the seal on the cylinder head. These slips cause shearing of the joint. As a result, not only does the seal wear out quickly, but in addition the sealing parts of the seal are positioned in a configuration that no longer ensures tightness around the ducts.

  It is known to put a lubricating product between the sealing parts of the seal and the flanges of the exhaust manifold, but the shear stresses 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 seals is high.

  OBJECT OF THE INVENTION The object of the invention is to reduce the wear of the sealing parts of a flat gasket and that these sealing portions remain correctly positioned relative to the surfaces of the parts to be sealed that are likely to move. one with respect to the other.

  For this purpose, 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 part between the sealing parts, in which each part of link comprises at least one frangible zone, that is to say an area that is likely to be broken.

  Thanks to the use of a flat gasket according to the invention, when the two parts between which the sealing is made begin to move relative to each other, the tensile and compressive stresses exerted by a part sealing on another sealing portion of the seal cause rupture of the frangible zone of the connecting portion between the two sealing portions.

  The sealing portions of the flat gasket then become completely independent of one another and no longer suffer the tensile and compressive stresses exerted by the neighboring sealing part or parts. The sealing portions 2886363 3 of the flat gasket then move relative to one or the other of said parts independently of each other.

  Thus, the sealing parts of the seal have a longer life and remain correctly positioned relative to the surfaces of the parts to be sealed.

  According to another advantageous characteristic of the flat gasket according to the invention, said frangible zone is formed by a dotted cut-out of each connecting part.

  According to another advantageous characteristic of the flat gasket according to the invention, said frangible zone is formed by notches on the edges of each connecting part.

  According to another advantageous characteristic of the flat gasket according to the invention, said frangible zone is formed by a thinning of the thickness of each connecting portion.

  According to another characteristic of the flat gasket according to the invention, one of the sealing parts comprises a first circular 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 characteristic of the flat gasket according to the invention, one of the sealing parts comprises a second oblong opening extending in the direction of the first opening.

  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 said sealing portion are intended to be traversed by said centering elements.

  According to a first feature of the assembly according to the invention, the first part, the second part 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, 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 an exhaust cylinder block cylinder head, an exhaust manifold and a flat gasket according to the invention; - Figure 2 is a view along section A-A of a portion of the assembly of Figure 1, cold, after assembly and before any operation; - Figure 3 is a view according to section A-A of a portion of the assembly of Figure 1 to hot after a few minutes of operation; FIG. 1 diagrammatically shows an assembly of a motor vehicle comprising a cylinder block exhaust head 10, called an exhaust cylinder head, an exhaust manifold and a flat metal gasket. the connection between the exhaust cylinder head and the exhaust manifold.

  The exhaust head 10 has four ducts 11, 12, 13, 14 for outputting exhaust gases to four further 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 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 20 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, secondly, a connecting portion 32,34,36 between each sealing portion 31, 33,35 37.

  Each sealing portion 31,33,35,37 comprises a central opening 91, 92,93,94 of exhaust gas passage intended to come during the mounting of the flat gasket 30 opposite, on the one hand, of the mouth of the duct 11,12,13,14 corresponding to the cylinder head 10 and, secondly, 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. Alternatively, more than two studs per conduit or less than two studs per conduit may be provided.

  The through hole 86 of the flange 62 of the exhaust manifold 20 is a circular centering hole for receiving the bolt 52 of diameter adjusted to the diameter of said stud 52 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.

  However, a seal mounting system on the manifold other than a centering hole and an oblong hole may be used, for example using three oblong holes.

  As for the manifold 20, the flat gasket 30 comprises on the sealing portion 33, close to the center of the flat gasket 30, the opening 82 intended to receive the stud 52 of diameter adjusted to the diameter of said bolt 52, playing the role of centering hole, to center the flat gasket at a point on the cylinder head 10. The flat gasket 30 also comprises on the sealing portion 37 located at one end of the flat gasket 30, the oblong opening 84 called oblong hole s extending towards the centering hole 82, to prevent the rotation of the flat gasket 30 about the centering hole 82.

  In order for the flat gasket 30 to be mounted on the cylinder head 10, the other openings 81, 83, 81A, 82A, 83A, 84A of the gasket are circular and have a diameter greater than the diameter of the studs 51, 51A, 52A, 53, 53A, 54A passing through them.

  Only the sealing portion 33 of the seal 30 comprising the centering hole 82 is directly integral with the yoke 10, just as the flange 62 of the collector 20 is directly integral with the yoke 10.

  Advantageously, according to the invention, each connecting portion 32, 34, 36 comprises at least one breakable zone 95, 96, 97 which is adapted to yield, after a few minutes of operation of the motor, in order to make the sealing portions 31 , 33,35,37 of the flat gasket 30 independent of each other. Here, each frangible zone 95, 96, 97 is formed by notches on the edges of the connecting portion 32, 34, 36. These notches act as breakthroughs.

  Alternatively, it can be provided that the frangible zone is formed by a pre-cut dashed of each connecting portion, or by a thinning of the thickness of each connecting portion.

  Each sealing portion 31,33,35,37 of the flat gasket 30 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 of the two parts 10,20, the flat joint plane being the plane separating the surface of one of the parts in contact with one of the surfaces. of the flat gasket 30, to maintain a good seal between the two parts. This rib 75,76, 77,78 of the sealing portion 31,33,35,37 of the flat gasket 30 has a certain height. When one will come to tighten the two parts 10,20, one creates a line of pressure, around this rib 95, 96,97,98, which guarantees the sealing 31,33,35,37.

  The surfaces of the connecting portions 32, 34, 36 are free from bearing with respect to 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 relative 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. It is also possible to use a monobloc flange.

  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. Here, the cylinder head 10 , the manifold 20 and the flat gasket 30 are made of different materials and are subjected to different temperatures, which causes differences in expansion between the cylinder head 10, the manifold 20 and the flat gasket 30. Alternatively, it is also possible to use materials identical at different temperatures.

  The cylinder head 10 dilates weakly. In FIG. 3, the displacement of the cylinder head 10 due to this expansion is represented by the arrows M and N. The exhaust manifold 20 and in particular its flanges 61, 62, 63, 64 are expanded more than the cylinder head. 10 which gives rise to a displacement of the manifold 20 greater than that of the cylinder head 10, as shown by the displacement arrows I and J in the drawing of FIG. 3. Finally, the flat gasket 30 also undergoes some expansion. different from the dilation of the cylinder head 10 and that of the manifold 20. Being positioned between the cylinder head 10 and the manifold 20, the flat gasket 30 undergoes a displacement between the displacement of the cylinder head 10 and that of the manifold 20, as shown on FIG. FIG. 3 by the displacement arrows K and L. Between a cold position shown in FIG. 2 and a hot position shown in FIG. 3, each non-centered flange 61, 63, 64 relative to the yoke 10 rubs on the flat gasket 30. Similarly, the cylinder head 10 during its expansion rubs on the non-centered portions 31, 35, 37 of the flat gasket 30. The non-centered sealing parts 31, 35, 37 of the flat gasket 30 are thus driven. by the movements of the flanges 61,63,64 and the displacement of the cylinder head 10, which causes traction and / or compression in the connecting portions 32,34,36 of the flat gasket 30.

  After a few moments of operation of the motor vehicle, the tensile and compressive stresses cause rupture of the frangible zones 95, 96, 97 of the connecting portions 32, 34, 36 of the flat gasket 30, as shown in FIG.

  The sealing portions 31, 33, 35, 37 of the flat gasket 30 then become completely independent of each other and no longer undergo the tensile and compressive stresses exerted by the adjacent sealing parts 31, 33, 35, 37 . The non-centered sealing portions 31, 35, 37 of the flat gasket 30 then move relative to the cylinder head 10 or to the flanges 61, 63, 64 of the manifold 20 independently of one another.

  Thus, the sealing portions 31, 33, 35, 37 of the flat gasket 30 are less stressed in tension and in compression, so they wear out less quickly, and they remain correctly positioned on the surfaces of the cylinder head 10 and the manifold 20. around the exhaust ducts 11,12,13,14,21,22,23,24.

  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.

  It is also possible to provide a lubricating product between the flat surfaces of the collector flanges and the sealing portions of the flat gasket to reduce the wear of the sealing parts by the significant friction of the flanges on these sealing parts.

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) has at least one breakable zone (95, 96, 97).   2. Flat gasket (30) according to claim 1, characterized in that said frangible zone (95,96,97) is formed by notches on the edges of each connecting portion (32,34,36).   3. flat gasket (30) metal according to one of the preceding claims, characterized in that said frangible zone (95,96,97) is formed by a dashed pre-cut of each connecting portion (32, 34,36).   4. flat gasket (30) according to one of the preceding claims, characterized in that said frangible zone (95,96,97) is formed by a thinning of the thickness of each connecting portion (32,34,36 ).   5. flat gasket (30) according to one of the preceding claims, characterized in that one of the sealing portions (33) comprises a first opening (82) for receiving a cylindrical centering element (52), belonging one of said pieces (10), of diameter adjusted to the diameter of said member (52).   6. Flat gasket (30) metal according to the preceding claim, characterized in that one of the sealing portions (37) comprises a second opening (84) oblong extending towards the first opening (82).   7. An assembly comprising two pieces (10, 20) to be joined to each other, 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, 88,88A) 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 5 and 6 ensuring the connection between the two parts (10, 20), the first and the second opening (82, 84) of said sealing portions (33, 37) are intended to be traversed by said centering elements (51, 51A, 52, 52A, 53, 53A, 54, 54A).   8. An assembly according to claim 7, characterized in that the first piece (10), the second piece (20) and the flat gasket (30) are of different materials.   9. Assembly according to one of claims 7 or 8, characterized in that it comprises a lubricant between the second part (20) and the sealing parts (31,33,35,37) of the flat gasket (30). ).   10. Assembly according to one of claims 7 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.