FR2876147A1 - EXHAUST CONDUIT - Google Patents

Abstract

The invention relates to an exhaust duct (1) which comprises, on the one hand, an outer tube (3) and an inner tube (2) positioned inside the outer tube (3) so as to delimit between these two tubes (2; 3), a peripheral volume (4) inside which is implanted a material (5) for thermal insulation of this conduit (1), on the other hand and at a first end (6) of this duct (1), a first means (8) for connection to a first exhaust element and, secondly and at a second end (7) of this duct (1), second means (9) for a connection of this duct (1) to a second exhaust element that comprises said exhaust line.This duct (1) is characterized by the fact that it comprises, close to its second end (7), means (10) for preventing the penetration of the exhaust gas, circulating inside the inner tube (2), in the peripheral volume (4) delimited by this inner tube (2) and the outer tube (3).

Description

The present invention relates to an exhaust duct that comprises a

  exhaust line of internal combustion engine.

  This invention relates to the field of the automotive industry and more particularly that of the manufacture of equipment ensuring the escape of gases from the combustion of a fuel by an internal combustion engine.

  In this respect, it will be observed that such an engine is completed by an exhaust line comprising at least one exhaust duct, for example consisting of an exhaust downcomer connected, on the one hand, to the engine via a collector and, secondly, to a silencer and / or a gas depollution element such as a particulate filter.

  It is, more particularly, within such an exhaust descent that circulates the exhaust gas which, because of the proximity of the engine, have a particularly high temperature.

  However, such an exhaust descent passes close to elements and organs (filters, hoses ...), in particular located in the engine compartment, likely to undergo damage under the effect of a high temperature and of which protection needs to be ensured.

  Such an exhaust descent may, again, be connected to a pollution control element (catalyst, particulate filter, etc.) located downstream of this exhaust descent, and whose operation is optimal for exhaust gases. at high temperature so that it is necessary to maintain these gases at a high temperature until they arrive in said depollution element.

  To do this, it was imagined an exhaust descent comprising two tubes including an outer tube and an inner tube.

  This inner tube is positioned inside the outer tube so as to delimit, between these two tubes, a peripheral volume inside which is implanted a material for thermal insulation of the exhaust descent.

  In such an embodiment, the peripheral volume receiving the insulating material communicates, at one of its ends, with the internal volume of the inner tube within which the exhaust gases circulate. These gases are then capable of penetrating into the peripheral volume and of being in contact with the insulating material, which must then be chosen to have good resistance to these gases and to high temperatures so as to avoid any degradation. In this regard, it will be observed that an insulating material having such performance is particularly expensive which considerably increases the cost of such an exhaust downhill.

  In addition and in order to define a peripheral volume capable of accommodating an insulating material, the outer tube must be positioned appropriately relative to the inner tube which is ensured by means of indentations made at this inner tube or ( and preferably) of this outer tube and which bear against this outer tube, respectively, this inner tube.

  Such indentations adopt, for example, the shape of punches and have drawbacks consisting, on the one hand, in weakening of the exhaust descent and, on the other hand, in the creation of a thermal bridge between the tubes. internal and external resulting in poor performance in terms of insulation, or even a total absence of insulation, the descent exhaust.

  The present invention is designed to overcome the disadvantages of exhaust pipes of the state of the art.

  For this purpose, the invention relates to an exhaust duct that comprises an exhaust line of an internal combustion engine and which comprises, on the one hand, an outer tube and an inner tube positioned inside the outer tube of in such a way as to delimit, between these two tubes, a peripheral volume inside which is implanted a material for a thermal insulation of this duct, on the other hand and at a first end of this exhaust duct, a first means for a connection of this exhaust duct to a first exhaust element, in particular an exhaust gas manifold and, secondly and at a second end of this exhaust duct, a second means for a connection of this conduit to a second exhaust element that includes said exhaust line. This exhaust duct is characterized in that it comprises, near its second end, means for preventing the penetration of the exhaust gas, circulating inside the inner tube, in the peripheral volume defined by this inner tube and outer tube.

  Another feature is that the means for preventing gas penetration into the peripheral volume is constituted by a ring engaged over the inner tube and over which is positioned the outer tube and / or the second connecting means.

  According to an additional characteristic, the second connecting means is, on the one hand, positioned over said ring and, on the other hand, fitted inside or over the outer tube of which said second connecting means is rendered. solidarity, especially by welding.

  Yet another characteristic relates to the fact that the ring is engaged over the inner tube with the possibility of displacement relative to this inner tube and / or the outer tube and / or the second connecting means, while the conduit comprises means to maintain the ring engaged on the inner tube In fact, the means for holding the ring on the inner tube are constituted by a shoulder that has, internally, the second connecting means and which cooperates with this ring.

  According to an additional feature, the ring is made of a metallic material and is more particularly constituted by a wire mesh. However, this ring may, again, be made of a thermal insulating material, more particularly based on fibers having a high thermal resistance.

  Another feature is that the inner and outer tubes are made integral at the first connecting means, in particular by welding.

  The invention also relates to an exhaust descent that includes an exhaust line of an internal combustion engine and which comprises or consists of an exhaust duct as described above.

  Finally, the invention relates to an exhaust line of an internal combustion engine comprising an exhaust duct as described above.

  The advantages of the present invention consist in that the conduit comprises means for preventing penetration of the gases into the peripheral volume, which prevents these gases from coming into contact with the insulating material which then undergoes no degradation.

  This allows the use of an insulating material which, since it is protected from the exhaust gas, may have a mechanical strength substantially lower than that of the insulating material used in the state of the art and, therefore, present a cost substantially lower than that of the insulating material of the state of the art.

  Another advantage is that, on the one hand, the inner and outer tubes are made integral with the first connecting means and, on the other hand, the means for preventing penetration of the gases into the peripheral volume are constituted by a ring, located at the second end of the duct, engaged over the inner tube and over which is positioned the outer tube and / or the second connecting means, this with the possibility of displacement of this ring. Such an embodiment allows, on the one hand, a relative movement of the inner tube relative to the outer tube due to differential thermal expansion phenomena and, on the other hand, a suitable positioning of this inner tube relative to the outer tube and the second connecting means, this avoiding the aforementioned disadvantages related to the indentations and appropriately delimiting the peripheral volume.

  Other objects and advantages of the present invention will become apparent from the following description relating to embodiments which are given by way of indicative and non-limiting examples.

  The understanding of this description will be facilitated with reference to the drawing attached in the appendix and in which: - Figure 1 is a schematic and sectional view of an exhaust duct according to the present invention; - Figure 2 is a schematic and detailed view of the second end of the exhaust duct illustrated in Figure 1.

  The present invention relates to the field of the automotive industry and more particularly that of the manufacture of equipment ensuring the escape of gases from the combustion of a fuel by an internal combustion engine.

  As shown in the appended figures, the invention relates to an exhaust duct 1 which comprises an exhaust line of internal combustion engine. In this regard, it should be noted that such an exhaust duct 1 is preferably constituted by an exhaust descent knowing that the present invention is not, however, in any way limited.

  Such an exhaust duct 1 comprises an inner tube 2 inside which the exhaust gases circulate. This inner tube 2 can be made in one piece but is preferably made from two assembled half-shells assembled, in particular by welding, which advantageously makes it possible to give such a tube 2 a complex shape, adapted to its environment, especially within an engine compartment.

  This exhaust duct 1 comprises, again, an outer tube 3 inside which said inner tube 2 is implanted, this outer tube 3 being made, preferably, from two pressed half-shells assembled, in particular by welding, this on top of said inner tube 2. Such an assembly of half shells again makes it possible to give this outer tube 3 a complex shape and to position, in an easy and appropriate manner, the inner tube 2 inside this tube external 3.

  In this regard, it will be observed that the positioning of the inner tube 2 inside the outer tube 3 is made so as to delimit between these two tubes 2; 3, a peripheral volume 4 inside which is implanted a material 5 designed to provide thermal insulation of the exhaust duct 1.

  Such insulation makes it possible, on the one hand, to protect the environment of the exhaust duct 1 with respect to the high temperature of the exhaust gases and, on the other hand, to keep the gases at a high temperature at the outlet of the duct 1 so as to allow the optimal operation of the depollution means placed downstream of this duct 1.

  As can be seen in FIG. 1, this exhaust duct 1 has two ends 6, 7 including a first end 6 situated upstream of the duct 1 and a second end 7 situated downstream of this duct 1, this being in accordance with FIG. flow direction of gases in this duct 1.

  This duct 1 then comprises, at this first end 6, a first means 8 for a connection of this exhaust duct 1 to a first exhaust element (not shown) and which, in the case of a duct 1 exhaust exhaust defined by an exhaust, is constituted by an exhaust gas manifold.

  It will be observed that it is, more particularly, at this first connecting means 8 that the inner tubes 2 and outer 3 are secured to one another 2 3, in particular by welding.

  In this regard, such a first connecting means 8 is preferably constituted by a flange or the like.

  This duct 1 comprises, again and at said second end 7, a second means 9 for a connection of this exhaust duct 1 to a second exhaust element (not shown) which, in the case of a duct Exhaust 1 defined by an exhaust descent, is constituted by a silencer or a depollution element, more particularly a particulate filter.

  In fact, this second connection means 9 may be constituted by a part making it possible to ensure the connection between a second exhaust element and either the inner tube 2 or the outer tube 3, or even these two tubes 2, 3.

  As can be seen in FIG. 2 corresponding to a preferred embodiment of the invention, this second connecting means 9, on the one hand, makes it possible to ensure the connection between the second exhaust element and the outer tube 3, and, on the other hand, is preferably constituted by a hoop or the like.

  According to the invention, this exhaust duct 1 comprises, near its second end 7, means 10 for preventing the penetration of the exhaust gas, flowing inside the inner tube 2, in the peripheral volume 4 delimited through this inner tube 2 and the outer tube 3.

  In fact, the means 10 for preventing penetration of the gases into the peripheral volume 4 consist of a ring 11, on the one hand, engaged over the inner tube 2 and, on the other hand, over which 11 is positioned the outer tube 2 and / or the second connecting means 9.

  According to a first embodiment not shown, it is the outer tube 2 which is engaged over this ring 11.

  However, and according to a preferred embodiment of the invention visible in FIG. 2, it is the second connection means 9 which is engaged above said ring 11.

  According to another characteristic of the invention, this second connection means 9 is, on the one hand, positioned over said ring 11 and, on the other hand, fitted over or, preferably, (FIG. inside the outer tube 3 of which the second connecting means 9 is secured, in particular by welding.

  It should be observed that said ring 11 is engaged over the inner tube 2, this with a possibility of displacement relative to the inner tube 2 and / or the outer tube 3 and / or the second connecting means 9.

  In this regard, it will be observed that the inner tube 2 is likely to adopt a relative movement with respect to the outer tube 3 due to thermal differential expansion phenomena. Such relative movement is, more particularly, perceptible at the second end 7 of the duct 1 since this inner tube 2 is only secured to the outer tube 3 at the first end 6 of the duct 1.

  According to a particular embodiment, this ring 11 is made integral with the inner tube 2 and is then able to move relative to the outer tube 3 and / or the second connecting means 9.

  According to another embodiment, this ring 11 can be secured to the outer tube 3 and / or the second connecting means 9 so that it is the inner tube 2 which is able to move relative to the ring 11.

  However, and according to a preferred embodiment of the invention visible in FIG. 2, the ring 11 is engaged over the inner tube 2 with the possibility of displacement relative to this inner tube 2, with respect to the outer tube 3 and with respect to the second connecting means 9.

  According to an additional characteristic, the exhaust duct 1 comprises, again, means 12 for holding the ring 11 engaged on the inner tube 2.

  Such means 12 advantageously make it possible to maintain the ring 11 on the inner tube 2 even at the relative movements of this inner tube 2 with respect to the outer tube 3 and with respect to the second connection means 9.

  In fact, such means 12 for holding the ring 11 on the inner tube 2 are constituted by a shoulder 13 which internally comprises the second connection means 9 and which cooperates with this ring 11.

  According to another characteristic of the invention, the ring 11 is made of a metallic material and is more particularly constituted by a wire mesh.

  However, according to another embodiment, this ring 11 may be made of a thermal insulating material, more particularly based on fibers having a high thermal resistance, for example non-intumescent fibers of the type described in EP patent application. 906,495.

  In this regard, it will be observed that the use of means 10 to prevent penetration of the exhaust gas into the peripheral volume 4 advantageously allows to avoid having, inside this peripheral volume 4 and all along exhaust pipe 1, an insulating material 5 particularly resistant to hot exhaust gases and, therefore, particularly expensive. Such an insulating material may, for example, be reserved solely for producing a ring 11 while the insulating material disposed in the peripheral volume 4, all along the exhaust duct 1 except at its second end 7 may consist of fibers having less mechanical strength and considerably cheaper.

  The use of these latter fibers may, again, be considered with a ring 11 made of a metallic material as mentioned above.

  The invention also relates to an exhaust descent that includes an exhaust line of an internal combustion engine and which comprises or consists of an exhaust duct 1 as described above.

  Finally, the invention relates to an exhaust line of an internal combustion engine having an exhaust duct 1 as described above.

  Although the invention has been described with respect to a particular embodiment, it is understood that it is in no way limited and that various modifications of shapes, materials and combinations thereof can be made. lo various elements without departing from the scope and spirit of the invention.

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Claims (12)

  1) Exhaust pipe (1) that comprises an exhaust line of an internal combustion engine and which comprises, on the one hand, an outer tube (3) and an inner tube (2) positioned inside the tube external device (3) so as to define, between these two tubes (2; 3), a peripheral volume (4) inside which is implanted a material (5) for thermal insulation of this conduit (1), on the other hand and at a first end (6) of this exhaust duct (1), a first means (8) for a connection of this exhaust duct (1) to a first exhaust element, in particular an exhaust gas manifold and, on the other hand and at a second end (7) of this exhaust duct (1), a second means (9) for a connection of this duct (1) to a second exhaust element that comprises said exhaust line, characterized in that it comprises, near its second end (7), means (1 0) to prevent penetration of the exhaust gas, circulating inside the inner tube (2), in the peripheral volume (4) defined by the inner tube (2) and the outer tube (3).   2) exhaust pipe (1) according to claim 1, characterized in that the means (10) for preventing penetration of the gas into the peripheral volume (4) consist of a ring (11) engaged over the inner tube (2) and over which (11) is positioned the outer tube (3) and / or the second connecting means (9).   3) exhaust duct (1) according to claim 2, characterized in that the second connecting means (9) is, on the one hand, positioned over said ring (11) and, secondly, fitted inside or over the outer tube (3) of which the second connecting means (9) is secured, in particular by welding.   4) exhaust pipe (1) according to any one of claims 2 or 3, characterized in that the ring (11) is engaged over the inner tube (2) with the possibility of movement relative to this tube internal (2) and / or the outer tube (3) and / or the second connecting means (9), while the conduit (1) comprises means (12) for holding the ring (11) engaged on the inner tube (2).   5) Exhaust pipe (1) according to claim 4, characterized in that the means (12) for holding the ring (11) on the inner tube (2) consist of a shoulder (13) that comprises, internally, the second connecting means (9) and which cooperates with this ring (11).   6) Exhaust pipe (1) according to any one of claims 2 to 5, characterized in that the ring (11) is made of a metallic material and is, more particularly, constituted by a wire mesh.   7) Exhaust pipe (1) according to any one of claims 2 to 5, characterized in that the ring (11) is made of a thermal insulating material, more particularly based on fibers having a high thermal resistance.   8) exhaust pipe (1) according to any one of the preceding claims, characterized in that the inner tube (2) and outer (3) are secured at the first connecting means (8), in particular by welding.   9) exhaust duct (1) according to any one of the preceding claims, characterized in that the first connecting means (8) is constituted by a flange, in particular for connection to an exhaust gas manifold.   10) exhaust pipe (1) according to any one of the preceding claims, characterized in that the second connecting means (9) is constituted by a hoop or the like.   11) An exhaust downcomer that includes an exhaust line of an internal combustion engine and which comprises or consists of an exhaust duct (1) according to any one of the preceding claims.   12) Exhaust line of an internal combustion engine and having an exhaust duct (1) according to any one of claims 1 to 10.