FR2930286A3 - Exhaust line connector for supercharged diesel engine of motor vehicle, has exhaust pipe for exhausting burnt gas, where burnt gas captured by recirculation pipe is distributed at rear with respect to direction of gas in exhaust pipe - Google Patents

Abstract

The connector has a burnt gas exhaust pipe (36) for exhausting burnt gas towards the atmosphere and extended along a median line. A burnt gas recirculation pipe (53) is connected on the exhaust pipe in a tapping point and extended along another median line. The tangent to the latter line at the tapping point and the former line form an obtuse angle of 135 degrees, such that the burnt gas captured by the recirculation pipe is distributed at the rear with respect to the direction of the gas in the exhaust pipe. An independent claim is also included for an internal combustion engine comprising a gas intake line.

Description

TECHNICAL FIELD TO WHICH THE INVENTION RELATES The present invention generally relates to the treatment of burnt gases from internal combustion engines. It relates more particularly to a connection of an exhaust line with a recirculation line of an internal combustion engine, to be installed downstream of a particulate filter of said exhaust line, comprising an exhaust pipe of gas burned towards the atmosphere that extends along a first average line, and a flue gas recirculation line in the internal combustion engine, which is stitched on the exhaust pipe at a given stitching point and which extends along a second average line. It also relates to an internal combustion engine having a fresh gas inlet line opening into cylinders, a burnt gas exhaust line which originates in the cylinders and which is provided with a particulate filter and a an exhaust pipe extending downstream of the particulate filter along a first average line, and a recirculation line of the flue gases which originates in the exhaust line, which opens into the intake line and which comprises a recirculation pipe stitched on the exhaust pipe at a given stitching point and extending along a second average line.

TECHNOLOGICAL BACKGROUND On this type of engine, the recirculation line (EGR) of the flue gases is stitched on the exhaust line downstream of the particulate filter so that the flue gases captured by the recirculation line are in advance. filtered by the particulate filter before being reinjected into the engine. As a result, the particles do not foul the recirculation line and the engine emits a small number of these polluting particles into the atmosphere. The particulate filter generally consists of a bundle of channels, one half of which has open inlets and closed outlets and the other half of which, on the contrary, has closed inlets and open outlets.

These channels also have porous walls so that the flue gases entering the particle filter through the channels whose inputs are open, pass through the porous walls and emerge from the particulate filter through the channels whose outlets are open. Crossing the porous walls of the channels makes it possible to separate the polluting particles from the flue gas stream.

In order to perform this function of filtering the particles, the porous walls of the channels are made of materials having very high hardnesses (silicon, cordierite, etc.).

During the first hours of operation of the internal combustion engine, fragments of porous walls inadvertently detach from the channels of the particulate filter. Part of these fragments is directly released into the atmosphere while the other part of these fragments is reinjected into the cylinders via the recirculation line (EGR) and the engine intake line. When they enter the intake line, these fragments pass through the compressor of the engine and hit the vanes of this compressor. These fragments of significant hardness then deteriorate the blades of the compressor, which may not only change their performance but also cause their breakage. Moreover, when they arrive in the engine, some of these fragments are mixed with the lubricating oil of the cylinders, which causes premature wear of the engine.

OBJECT OF THE INVENTION In order to overcome the aforementioned drawbacks of the state of the art, the present invention proposes a new coupling and a new motor making it possible to prevent particle filter fragments from entering the recirculation line of the engine. .

More particularly, according to the invention there is provided a coupling and an internal combustion engine as defined in the introduction, in which the tangent to the second mean line at the stitching point forms with the first mean line an obtuse angle, of such so that the burnt gases captured by the recirculation pipe are substantially backward in relation to their direction in the exhaust pipe. The obtuse angle corresponds to the angle formed by the trajectory of the burnt gases which, while circulating in the exhaust pipe, are taken by the recirculation pipe. Thanks to the invention, the particle fragments of the particle filter entrained in the flue gas flow remain in the exhaust pipe and are not removed by the recirculation pipe. Indeed, because of their inertia, they tend to follow a rectilinear trajectory, so that they can not follow the path bent more than 90 degrees of the burnt gases taken by the recirculation pipe. The set of fragments thus emerges from the outlet of the exhaust pipe and is directly removed from the engine. According to a first advantageous characteristic of the connector and the motor according to the invention, said obtuse angle is between 100 and 150 degrees and is preferably equal to 135 degrees. Thus, thanks to the inclination of the recirculation pipe with respect to the exhaust pipe, if some fragments still pass through the opening formed by the quilting of the recirculation pipe on the exhaust pipe, they strike the internal face of the recirculation pipe and bounce on the latter in the direction of the exhaust pipe. These few fragments are also directly removed from the engine without passing through the turbocharger and cylinders. According to another advantageous characteristic of the engine according to the invention, when the latter is in the position of use, the recirculation pipe extends from the point of stitching upwards of the internal combustion engine. The channel fragments of the particulate filter have high densities and are therefore subject to gravity. Thus, thanks to the orientation of the recirculation pipe to the top of the engine, the fragments do not go up in the recirculation pipe but instead remain in the exhaust line and are directly removed from the engine. According to another advantageous characteristic of the coupling and the engine according to the invention, the exhaust pipe forms a bend and the tapping of the recirculation pipe on the exhaust pipe is located inside the bend or at the outlet. elbow, the inner side of this elbow. Thus, because of their inertia, the particle filter channel fragments are drawn outwardly of the elbow, which helps to prevent them from entering the recirculation line.

According to another advantageous characteristic of the coupling and the motor according to the invention, the exhaust pipe has on its internal face a deflection member for the flue gases placed near the edge of the tapping opening of the recirculation pipe, upstream of it. This deflection member is thus positioned in such a way that it prints a flow path of the flue gas and the fragments directed opposite the quilting opening, which contributes to hindering the entry of the fragments into the duct. recirculation. DETAILED DESCRIPTION OF AN EXEMPLARY EMBODIMENT The following description, with reference to the appended drawings, given by way of non-limiting example, will make it clear what the invention consists of and how it can be achieved. In the accompanying drawings: - Figure 1 is a schematic view of an internal combustion engine according to the invention; and - Figures 2 to 4 are schematic views of three embodiments of the connector according to the invention.

In the description, the terms upstream and downstream will be used in the direction of gas flow, from the point of sampling fresh gases in the atmosphere to the exit of the flue gases by a silencer 35. In FIG. schematically shows an internal combustion engine 1 which comprises a cylinder block 10 provided here with four cylinders 11. This engine is supercharged diesel type. It therefore comprises a turbocharger 40 provided with two impeller wheels that rotate together and forming a turbine 42 and a compressor 41. Upstream of the cylinders 11, the internal combustion engine 1 comprises an intake line 20 which comprises an air filter 21 which filters the fresh air taken from the atmosphere. This inlet line 20 passes through the compressor 41, so that the fresh air filtered by the air filter 21 is compressed. It further comprises a main air cooler 22 which cools this fresh compressed air. The inlet line 20 finally opens into an air distributor 23 which brings fresh air into each of the cylinders 11 of the cylinder block 10.

At the outlet of the cylinders 11, the internal combustion engine 1 comprises an exhaust manifold 31 of burnt gas which is connected to an exhaust line 30 extending to the silencer 35. This exhaust line 30 passes through the turbine 42, so that the burnt gases rapidly ejected from the rollers 11 drive in rotation its impeller and thus actuate the compressor 41. The exhaust line 30 further comprises means for treating the burnt gases formed here by a catalytic converter 32 successively equipped, according to the flow direction of the flue gases, an oxidation catalyst 33 and a particulate filter 34. The outlet of this catalytic converter 32 is connected to the silencer 35 by a primary duct 37 extending according to a mean line A1. This average line A1 corresponds to the geometric line that passes through the center of gravity of each cross section of the primary pipe 37. The internal combustion engine 1 comprises e also a recirculation line 50 EGR flue gas which originates in the exhaust line 30 and which opens into the inlet line 20 via an EGR valve 52 for regulating the flow of recirculating gas. This recirculation line 50 also accommodates an EGR cooler 51 intended to cool the flue gases taken from the exhaust line 30. As shown more particularly in FIG. 2, this recirculation line 50 comprises in particular a secondary pipe 54 stitched onto the primary pipe 37 at a stitching point P1, which extends to the EGR cooler 41 along a mean line A2. The tapping of the secondary pipe 54 on the primary pipe 37 forms in the side wall of the primary pipe 37 a stitching opening centered on the stitching point P1. The branching of the secondary pipe 54 on the primary pipe 37 can be carried out in various ways.

According to a first embodiment, this stitching is carried out by means of a coupling, that is to say of a one-piece piece after molding, comprising an exhaust pipe 36 and a recirculation pipe 53 which originates in the side wall of the exhaust pipe 36. Preferably, the exhaust pipe 36 forms only part of the primary pipe 37 and the recirculation pipe 53 forms only part of the secondary pipe 54. The inputs and outputs of these exhaust ducts 36 and recirculation 53 are then connected to the remaining portions of the primary 37 and secondary pipes 54 for example by welding.

As a variant, this connection may have a length sufficient for its exhaust duct 36 to form the whole of the primary duct 37 and for its recirculation duct 53 to constitute the set of the secondary duct 54. According to a second embodiment of realization, the primary 37 and secondary pipes 54 are two separate parts. The primary pipe 37 is then called the exhaust pipe 36 while the secondary pipe 54 is called the recirculation pipe 53. In this case, the tap of the recirculation pipe 53 on the exhaust pipe 36 is made by directly connecting the the mouth of the recirculation pipe 53 on the tapping opening of the exhaust pipe 36. This connection can for example be made by welding. Nevertheless, according to a particularly advantageous characteristic of the invention, the second average line A2 of the recirculation pipe 53 has a tangent A3 at the stitching point P1 which forms, with the first average line Al of the pipe exhaust 36, an obtuse angle B1, so that the flue gas captured by the recirculation pipe 53 substantially backward relative to their direction in the exhaust pipe 36. Advantageously, this obtuse angle B1 is between 100 and 150 degrees and is preferably 135 degrees. As shown in FIG. 2, the average line A1 of the exhaust duct 36 is rectilinear while the average line A2 of the recirculation duct 53 is curved. These two middle lines Al. A2 are here coplanar and secant. Alternatively, the average line A1 and the tangent A3 could be located in parallel planes and close to each other, but not confused. According to this variant, the obtuse angle B1 then corresponds to the angle formed by the orthogonal projection of the tangent A3 in the plane of the average line A1. Advantageously, the recirculation pipe 53 extends from the stitching point P1 towards the top of the internal combustion engine 1. In other words, the engine being in the position of use (for example in a motor vehicle), the average line A2 of the recirculation pipe has at least one portion that extends from the tapping point Al above this tapping point A1. When the internal combustion engine 1 is running, the fresh gases taken from the atmosphere via the intake line 20 are filtered by the air filter 21, compressed by the compressor 41, cooled by the air cooler 22, and finally burned in the cylinders 11 with fuel. At their outlet from the cylinders 11, the flue gases are expanded in the turbine 42, then treated and filtered by the oxidation catalyst 33 and the particulate filter 34. Part of these treated and filtered exhaust gases are directly discharged into the atmosphere. atmosphere through the silencer 35, while another part of these gases burned, the EGR gas, is taken by the recirculation line 50, cooled by the EGR cooler 51, and then re-injected into the intake line 20, between the air filter 21 and compressor 41. During the first hours of operation of the internal combustion engine 1, solid fragments are detached from the walls of the particulate filter 34 and rush into the exhaust pipe 36. the invention, these fragments remain in the exhaust pipe 36 and are not taken by the recirculation pipe 53. Indeed, because of their inertia, they follow, as far as possible, rectilinear trajectories, i They are parallel to the average line A1 of the exhaust pipe 36, 35 and therefore can not follow the bent path more than 90 degrees of the EGR gas. These fragments are therefore directly discharged into the atmosphere through the silencer 35.

In addition, given the orientation of the recirculation line 53 towards the top of the engine, the fragments which are subjected to gravity do not rise in the recirculation line 53 but instead remain in the exhaust line 36.

The present invention is not limited to this embodiment, but the skilled person will be able to make any variant within his mind. In particular, according to a variant of the invention shown in Figure 3, it can be provided that the exhaust pipe 36 forms a bend and that the opening formed by the tapping of the recirculation pipe 53 on the exhaust pipe 36 either inside the elbow or at the exit of the elbow, on the inside of that elbow. More specifically here, the exhaust pipe 36 forms two elbows 37, 38 successive 90 degrees joined by a straight portion. The stitching point P1 of the recirculation pipe 53 on the exhaust pipe 36 is located on this rectilinear portion between the two elbows 37, 38, on the inner side of these elbows. In other words, since the wall of the exhaust duct 36 has an infinity of longitudinal guidelines extending from one elbow to the other, the stitching point P1 is located on the shortest longitudinal guideline. Thus, because of their inertia, the fragments that are detached from the walls of the particulate filter are driven outwardly of the bends, which helps to prevent them from entering the recirculation pipe 53. Of course, according to this variant the exhaust duct 36 and the recirculation duct 53 may be formed integrally with the connection or may be connected to each other, for example by welding.

According to another variant of the invention shown in FIG. 4, the exhaust pipe 36 has on its inner face a deflection member 39 for the flue gases, placed close to the edge of the tapping opening of the recirculation pipe. 53 on the exhaust pipe 36, upstream of this opening. This member is preferably placed on the edge of this opening.

This deflection member 39 may be formed by a boss of the inner face of the exhaust pipe 36, by a flap reported in the exhaust pipe 36, or by any other means coming from formation with the exhaust pipe or reported therein, and adapted to alter the flow of the flue gases so as to deflect them away from the stitching opening. The deflection member 39 thus contributes to blocking the entry of the wall fragments of the particulate filter 34 into the recirculation line 36.

Claims (9)

REVENDICATIONS1. Connection of an exhaust line (30) with a recirculation line (50) of an internal combustion engine (1) to be installed downstream of a particulate filter (34) of said exhaust line ( 30), comprising: - an exhaust duct (36) of the flue gases to the atmosphere which extends along a first average line (Al), - a recirculation duct (53) of the flue gases in the combustion engine internal section (1), which is stitched on the exhaust pipe (36) at a stitching point (P1) and which extends along a second mean line (A2), characterized in that the tangent (A3) at the second average line (A2) at the stitching point (P1) forms with the first mean line (A1) an obtuse angle (B1) so that the burnt gases captured by the recirculation line (53) are substantially backward relative to to their direction in the exhaust pipe (36). 2. A coupling according to the preceding claim, wherein said obtuse angle (B1) is between 100 and 150 degrees and is preferably equal to 135 degrees. 3. Connection according to one of the preceding claims, wherein the exhaust pipe (36) forms a bend and wherein the tapping of the recirculation pipe (53) on the exhaust pipe (36) is located at inside the elbow or at the exit of the elbow, the inner side of this elbow. 4. Connection according to one of the preceding claims, wherein the exhaust pipe (36) has on its inner face a deflection member (39) of the flue gas placed near the edge of the opening of the pipe stitching recirculation (53), upstream thereof. 5. Internal combustion engine (1) comprising: - an inlet line (20) for fresh gas discharging into cylinders (11), - an exhaust line (30) for burnt gases that originates in the cylinders ( 11) and which is provided with a particulate filter (34) and an exhaust duct (36) extending downstream of said particulate filter (34) along a first average line (Al), and - a recirculation line (50) of the flue gas which originates in the exhaust line (30), which opens into the intake line (20) and which comprises a recirculation pipe (53) stitched on the pipe of exhaust (36) at a stitching point (P1) and extending along a second mean line (A2), characterized in that the tangent (A3) at the second mean line (A2) at the stitching point (P1) forms with the first average line (A1) an obtuse angle (B1), so that the burnt gases captured by the recirculation pipe (53) substantially return to rearward of their direction in the exhaust pipe (36). 6. Internal combustion engine (1) according to the preceding claim, wherein said obtuse angle (B1) is between 100 and 150 degrees and is preferably equal to 135 degrees. 7. Internal combustion engine (1) according to one of claims 5 and 6, wherein, the internal combustion engine being in the use position, the recirculation pipe (53) extends from the stitching point ( P1) towards the top of the internal combustion engine (1). 8. Internal combustion engine (1) according to one of claims 5 to 7, wherein the exhaust pipe (36) forms a bend and wherein the tapping of the recirculation pipe (53) on the pipe of Exhaust (36) is located inside the elbow or at the exit of the elbow, the inner side of this elbow. 9. Internal combustion engine (1) according to one of claims 5 to 8, wherein the exhaust pipe (36) has on its inner face a deflection member (39) of the flue gas placed near the edge of the tapping opening of the recirculation pipe (53), upstream thereof. 9