EP0842351A1

EP0842351A1 - Internal combustion engine exhaust device

Info

Publication number: EP0842351A1
Application number: EP96924960A
Authority: EP
Inventors: Michel Decerprit; Olivier Guibert; Raymond Henry; Michel Jan
Original assignee: Renault SAS; Regie Nationale des Usines Renault
Current assignee: Renault SAS; Regie Nationale des Usines Renault
Priority date: 1995-07-28
Filing date: 1996-07-09
Publication date: 1998-05-20
Also published as: FR2737252B1; WO1997005370A1; FR2737252A1

Abstract

An internal combustion engine gas exhaust device comprising an exhaust manifold (1) attached to the cylinder head for collecting exhaust gases driven out of the cylinders, and an exhaust line (8) comprising pollutant removing and sound absorbing means. The manifold (1) is connected to the exhaust line (8) via a coupling system (9) having a flange (10), a mating flange (11) and a gasket (12) therebetween. The flange (10) integral with the exhaust manifold (1) and/or the mating flange (11) integral with the exhaust line (8) is (are) shaped in such a way that the gasket (12) is protected from the exhaust gases.

Description

EXHAUST DEVICE FOR INTERNAL COMBUSTION ENGINE

The present invention relates to an exhaust device for an internal combustion engine fitted in particular to a motor vehicle. The invention relates more particularly to the system for connecting the exhaust manifold to the exhaust line.

Conventionally, the device for exhausting the combustion gases of an internal combustion engine fitted to a motor vehicle comprises an exhaust manifold which is fixed to the cylinder head, this manifold comprising a plurality of pipes which provide the connection between the outlet orifices. various exhaust ducts formed in the cylinder head downstream of the exhaust valves and the inlet port of the exhaust line proper bringing the burnt gases to the atmosphere after having passed them through different capacities (catalytic converter , resonance pot, trigger pot, silent,

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The connection between the outlet of the manifold and the inlet of the exhaust line is provided by a connection system formed by a flange carried by the manifold and a counter-flange carried by the exhaust downpipe with interposition of a thick fiber or metal gasket. This connection system has the disadvantage of not remaining perfectly tight over time, due to the gradual destruction of the joint subjected to high temperatures and to the corrosive action of the burnt gases, which therefore leads to the discharge of burnt gases not cleaned up in the atmosphere.

The present invention therefore relates to an exhaust device overcoming the aforementioned drawbacks in that it comprises a perfectly sealed connection system, this connection system being at the same time simple and economical to produce.

The exhaust device for the burnt gases of an internal combustion engine according to the invention is of the type comprising an exhaust manifold fixed to the cylinder head for collecting the burnt gases expelled from the cylinders and an exhaust line comprising means pollution control and soundproofing, the manifold being connected to the exhaust line by a flange and counterflange connection system with the interposition of a seal.

According to the invention the exhaust device for an internal combustion engine is characterized in that the flange secured to the exhaust manifold and / or said counter flange secured to the exhaust line are shaped so as to protect the gasket sealing of burnt gases.

According to another characteristic of the exhaust device for internal combustion engine object of the invention, the seal is positioned radially around a tubular duct element channeling the flow of burnt gases, this duct element having an axial length suitable for isolating burnt gases the entire free internal face of the seal, traditionally exposed to the latter in assemblies nowadays.

According to one embodiment of the exhaust device for an internal combustion engine which is the subject of the invention, the duct element is formed by an annular shoulder carried by the flange, this shoulder defining a peripheral recess at the bottom of which is housed the seal. sealing, the counter-flange then being adapted to be housed in this peripheral recess of the flange, by enclosing the shoulder with a predetermined clearance.

According to this embodiment of the exhaust device for internal combustion engine object of the invention, the height of the shoulder is at least equal to 1.5 times the thickness of the seal.

According to another embodiment of the exhaust device for internal combustion engine object of the invention, the duct element is carried by the counter flange.

According to yet another embodiment of the exhaust device for an internal combustion engine which is the subject of the invention, the duct element is formed directly by the tubular end of the exhaust line, this end projecting above the joint plane of the counter-flange.

According to this last embodiment of the exhaust device for internal combustion engine object of the invention, the flange then has a suitable recess in which is housed the projecting end of the exhaust line, this recess being shaped to radially enclose all or part of this end.

According to another characteristic of the exhaust device for internal combustion engine object of the invention, the seal is positioned set back from the duct element so as to provide an annular cavity between the free internal face of the seal d and the conduit element.

The aims, aspects and advantages of the present invention will be better understood from the description of two embodiments of the invention, given by way of nonlimiting examples, with reference to the appended drawings, in which:

Figure 1 is a perspective view in partial section of a connection system between an exhaust manifold and the inlet of the exhaust line according to the present invention;

Figure 2 is a view similar to Figure 2, showing an alternative embodiment of the connection system according to the invention. In accordance with the figures, only the constituent elements of the exhaust device for a combustion engine have been shown, necessary for understanding the invention. To simplify the reading of the drawings, the same elements have the same references from one figure to another. In addition, the invention being described according to two variants containing characteristic elements whose function is basically identical, each element of the second embodiment has been referenced by a number consisting of the number of the figure to which it refers followed by a specific number common to all variants.

As can be seen in FIGS. 1 and 2, the exhaust device conventionally comprises an exhaust manifold of the "3Y" type, referenced 1, which is fixed on the cylinder head of an internal combustion engine, not shown, with four cylinders in line intended to be mounted for example transversely in the front compartment of a motor vehicle.

This manifold 1 therefore comprises four pipes 2,3,4,5, which ensure the evacuation of the burnt gases from each of the cylinders. The upstream ends of these pipes 2,3,4,5 are intended to be directly connected to the outlet orifices of the exhaust ducts formed in the cylinder head, by means of a fixing flange 6. The downstream ends of these pipes 2,3,4,5 are grouped two by two 2 and 3, 4 and 5 to form the first two "Y", which are in turn grouped into a third "Y" to lead to a single tube element 7 constituting the outlet of the manifold 1.

The outlet of the manifold 1 is fixed to the exhaust line, of which only the upstream end corresponding to the inlet of the downpipe 8 has been shown, by means of a gas-tight connection system 9. The connection system 9 comprises, in accordance with FIG. 1, a flange 10 integral with the manifold 1, surrounding the outlet orifice of the tube 7. This flange 10 is fixed to a counter-flange 11 integral with the downpipe 8 with interposition a bilobe-type annular seal 12.

The flange 10, obtained by any means known to a person skilled in the art and in particular by molding or even by stamping, has at its front end facing the counter-flange 11, a peripheral recess 14 delimited by an annular central shoulder 15 surrounding by extending the outlet of the tube 7. The counter-flange 11 is adapted to fit into this recess 14 by enclosing with a predetermined radial clearance, as small as possible, the shoulder 15. Screws (or studs) 16 engaged in corresponding eyelets 17 of the flange 10 and of the counter-flange 11 and suitable nuts allow these two parts to be tightened one against the other and to compress the seal 12 placed at the bottom of the recess 14.

This arrangement of the flange 10 and the counter-flange 11 therefore makes it possible both to center them one against the other and to isolate the seal 12 and in particular its inner face free from the flow of burnt gases, by interposing between it and the latter the shoulder 15. Thus protected, the seal 12 sees its lifespan considerably increase, which allows the connection system to remain perfectly sealed over time in accordance with pollution control standards prohibiting the discharge into the atmosphere of burnt gases that have not been cleaned up.

The height of the shoulder, that is to say the dimension over which its surface extends in the axial direction, is substantially greater than the thickness of the seal 12 and preferably equal to at least 1.5 times the latter. . Thus, the clamping of the shoulder 15 by the counter-flange 11 extends over a length sufficient to minimize contact between the seal 12 and the burnt gases.

Figure 2 shows an alternative embodiment of the connection system object of the invention. This system 29 similarly consists of a flange 210 extending at the end of the tube 7 and a counter-flange 211 carried by the tube 28 of the exhaust downpipe. The counter-flange 211 is however welded or crimped back from the inlet end 218 of the tube 28, which then projects out from the counter-flange 211. This position back from the counter-flange 211 allows to weld the latter on the downpipe 28 both from above and from below, without the risk of sending weld spatter in the exhaust downpipe. The facing flange 210 then has a central recess 219 obtained by example by simple milling, this recess being perfectly adapted to receive the end 218 of the tube 28 during the positioning of the counter-flange 211, with this time, the lowest possible axial clearance.

The seal 212 extending between the planar surfaces opposite the flange 210 and the counter flange 211 is then protected from the exhaust gases by the end 218 of the tube 28, projecting from the interior of the flange 210. The flange 210 and the counter-flange 211 are shaped so as to provide an annular cavity 220 between the wall 218 and the seal 212, so as to further isolate the latter from the gases of exhaust.

Of course, the invention is in no way limited to the embodiments described and illustrated which have been given only by way of examples.

On the contrary, the invention includes all the technical equivalents of the means described and their combinations if these are carried out according to the spirit.

Thus, the corresponding shapes of the flange and of the counter-flange which have been illustrated in FIGS. 1 and 2 can be perfectly reversed, the shoulder 15 and the recess 14 being carried by the counter-flange 11 or even the tubular end 7 of the exhaust manifold 1 projecting beyond the joint plane of the recessed flange, etc.

Claims

[1] Device for exhausting burnt gases from an internal combustion engine of the type comprising an exhaust manifold (1) fixed to the cylinder head to collect the burnt gases expelled from the cylinders and an exhaust line (28) comprising depollution and soundproofing means, the collector (1) being joined to the exhaust line (28) by a connection system (29) with flange (210) and counter-flange (211) with the interposition of a seal, characterized in that said counter-flange (211) secured to the exhaust line (28) is shaped so as to protect said seal (212) from burned gases.

[2] Device for exhausting burnt gases from an internal combustion engine according to claim 1, characterized in that said seal (212) is positioned radially around a tubular conduit element (218) channeling the flow of burnt gases, said conduit element having an axial length adapted to isolate the entire free interior face of said seal (212) from the burnt gases.

[3] Device for exhausting burnt gases from an internal combustion engine according to claim 2, characterized in that said conduit element is constituted by the tubular end (218) of the exhaust line (28), said end (218) extending projecting above the joint plane of the counter-flange (211).

[4] Device for exhausting burnt gases from an internal combustion engine according to claim 3, characterized in that the flange (210) has a suitable recess (219) in which said projecting end (218) is housed, said recess (219) being shaped to radially enclose all or part of said end (218).

[5] Device for exhausting burnt gases from an internal combustion engine according to any one of claims 2 to 7, characterized in that said seal (212) is positioned set back from said conduit element (218). ) so as to provide an annular cavity (220) between the free internal face of said seal (212) and said conduit element (218).