WO2014207335A1

WO2014207335A1 - Muffler intended to be mounted in the exhaust line of a heat engine

Info

Publication number: WO2014207335A1
Application number: PCT/FR2014/051271
Authority: WO
Inventors: Laurent Gagliardini
Original assignee: Technoboost
Priority date: 2013-06-25
Filing date: 2014-05-28
Publication date: 2014-12-31
Also published as: EP3014081A1; EP3014081B1; FR3007453B1; FR3007453A1

Abstract

The invention relates to a muffler (S) intended to be mounted in an exhaust line (L) of a heat engine (M), said muffler comprising one or more shells defining three volumes (1a, 1b, 2), referred to as upstream (1a), intermediate (1b) and downstream (2), arranged in succession and passed through by a plurality of pipes including: a supply pipe (10) for feeding the exhaust gases from the engine (M) into the intermediate volume (1b) via the upstream volume (1a); a so-called forward path pipe (12) for bringing the exhaust gases from the intermediate volume (1b) into the downstream volume (2); a so-called return path pipe (13) for feeding the exhaust gases from the downstream volume (2) into the upstream volume (1a) via the intermediate volume (1b); and a discharge pipe (14, 14') provided predominantly outside the shell(s) and leading out of the upstream volume (1a).

Description

SILENCER FOR EQUIPPING AN EXHAUST LINE OF A

THERMAL MOTOR

[Oooi] The present invention relates to a silencer for fitting an exhaust line of a heat engine. The invention also relates to an exhaust line of the type comprising such a silencer, as well as the vehicle that embodies it.

Vehicles powered by a combustion engine, also called internal combustion, comprise at least one exhaust line of combustion gases. In order to reduce noise pollution and to meet the rules of acoustic approval of vehicles, the exhaust line comprises in known manner a silencer. It is fixed under the vehicle body and terminates at one of its ends by a discharge pipe, also called cannula, which sometimes slightly exceeds the rear bumper when it comes to vehicles powered solely by a heat engine .

Particularly in the case where the vehicle is also powered by a second propulsion unit using an energy other than heat, such as an electric machine (hybrid electric vehicle) or a hydraulic motor (hybrid-air vehicle), or when the engine is connected to a compressed air tank (pneumatic hybrid vehicle), - or when the heat engine also uses gaseous fuel of the natural gas type - it is necessary to house one or more additional tanks / devices in the vehicle, in particular under cash. We then try to shorten, to compact the exhaust line and bodies of the silent type that it integrates. The line can then be shortened in such a way that the exhaust pipe which terminates it, at the outlet of the silencer, is under the body, at the front of the rear axle of the vehicle, for example at the second row of the vehicle. seats in the passenger compartment of the vehicle. It is ensured that the exhaust gases do not come up in the passenger compartment because, at the standstill, with the hybrid-type vehicles, the engine does not operate and in fact does not emit any gas. exhaust, and that in driving conditions, the speed is that the exhaust gas flow under the box and evacuate without difficulty towards the rear of the vehicle. However, shorten, compact the exhaust line can be difficult, insofar as the design of the exhaust line has an impact on the operation of the engine, including its filling air / fuel mixture , and that it appears desirable not to have to significantly change the control control of the engine according to whether it is the only means of propulsion of the vehicle or not. It is also important to maintain the same type of acoustic reflection for the muffler, especially the portion usually referred to as the intermediate muffler.

The object of the invention is then the development of an improved engine exhaust system muffler. These include designing a muffler more compact, or at least more adaptable dimensionally, while having acoustic performance at least as good. Incidentally, we seek to design a silencer with improved acoustic performance for a shortened exhaust line, compared to the performance of a silencer of a conventional exhaust line, the acoustic source with a shortened exhaust line being more close to the ears of the occupants.

The invention firstly relates to a silencer intended to equip an exhaust line of a heat engine, silent which comprises one or more envelope (s) which delimits (s) three volumes, said upstream, intermediate and downstream, arranged successively and traversed by a plurality of ducts, including: - a supply duct bringing the exhaust gas from the engine into the intermediate volume through the upstream volume, - a path conduit said "go> driving the exhaust gases from the intermediate volume into the downstream volume, a so-called "return" path duct leading the exhaust gases from the downstream volume to the upstream volume while passing through the intermediate volume, and a duct discharge disposed predominantly outside the envelope or envelopes and opening upstream volume.

The muffler therefore has the particularity of having a discharge conduit which is disposed substantially outside the envelopes, which is very interesting in terms of dimensioning: it can maintain a sufficient level of free volume in the envelopes to ensure the acoustic attenuation required, by "exiting" the exhaust duct, which, in fact, can be dimensioned so more free, in terms of length, shape (rectilinear or not) and orientation, according to, for example, that it runs along the envelope or envelopes "down" downstream or being oriented upstream of the silencer, "going up" to the exhaust line on the engine side. [0008] And contrary to what might have been feared, such positioning of the exhaust duct did not bring any disadvantage or problem, both acoustically and mechanically.

The term "upstream" and "downstream" is understood throughout the present text with reference to the general flow direction of the exhaust gases from the exhaust manifold of the engine to the outside of the vehicle. . In the same way, "successively" is to be understood according to this direction of general flow. Throughout the present text, "low", "high", "vertical" type spatial positioning indications are understood, such as the indications relating to the positioning of the muffler once mounted in the vehicle, which itself is positioned at the vehicle. stop on a horizontal plane.

[ooi o] Preferably, the silencer has three volumes divided into one, two or three envelopes.

[001 1] According to one embodiment, the silencer volumes are distributed in several envelopes delimited by side walls and transverse end walls called cups, said envelopes being connected to each other by at least two ducts crossing at least two cups opposite two successive envelopes.

With such an embodiment with several envelopes, the exhaust gases will go back and forth via predefined ducts (as detailed below), the ducts then fulfilling their usual role of guiding exhaust gases in closed volumes to mitigate the sound impact. But these conduits, or at least some of them, also play a mechanical role of linking the two envelopes together. This ensures the consistency of the whole without having to foresee (in any case more so mandatory) specific mechanical means to maintain correct relative positioning of the envelopes relative to each other.

Preferably, the exhaust duct runs along the upstream volume of the silencer, and possibly also the intermediate volume and also possibly also the downstream volume over a portion of at least their length.

Several variants are possible: it can go along the whole of the envelope or envelopes to open in the vicinity of the downstream part of the silencer, or beyond, it can also go along only part of the or envelopes, and open at the level of the intermediate volume or the downstream volume for example. It adapts its dimensioning (length, section) so that it fulfills its role properly, it can thus lead to underbody, for example in the vicinity of the level of the seats of rank two of the passenger compartment of the vehicle.

Preferably, the exhaust duct opens out of the upstream end transverse wall of the upstream envelope. This choice proved to be the most advantageous from the dimensional point of view, even if it may surprise, since, in fact, the duct "leaves" the silencer in its most upstream part, before, for example, to follow towards the downstream, the silencer on a suitable length.

According to a preferred embodiment, the exhaust duct opens the upstream cup of the envelope defining the upstream volume of the silencer. The silencer according to the invention may include several, including two exhaust ducts, including parallel to each other over at least a portion of their lengths. They may follow symmetrically the upstream envelope, on each side thereof, for example in the lower part.

The silencer according to the invention may also include several, including two, path paths "go", and / or more, including two path paths "return". We can indeed split each of the muffler ducts, especially to give more flexibility in the design of the muffler as a whole. The ducts thus split will have a smaller section than a unit duct, so as to keep the same gas channeling capacity at a given flow rate, and to maintain a similar pressure drop.

Preferably, the intermediate volume of the silencer according to the invention is substantially equal to or adjacent to the downstream volume thereof.

More preferably, the upstream volume of the silencer according to the invention is substantially twice as large as the intermediate volume and / or the downstream volume thereof. It is thus preferably equal to the sum of the intermediate and downstream volumes.

According to the proposed construction, preferably, the so-called "go" path duct is of a length less than that of the so-called "return" path duct, itself shorter than the duct length. evacuation. This choice (according to the conventions of acoustic diagrams) is optimal in terms of acoustic performance for the proposed silencer architecture.

The invention also relates to the body structure of a motor vehicle comprising a cockpit floor having a tunnel, such that said tunnel houses at least a portion of the silencer described above. The muffler thus has a configuration where the single envelope or the successive envelopes can be aligned longitudinally along the axis of the tunnel, which is coincident with or parallel to the longitudinal axis of the vehicle.

A great advantage of the silencer according to the invention is that it can easily be arranged in the tunnel. The space between the two envelopes, in the configuration with several envelopes, which makes, in fact, in this zone the quieter muffler in its section (its bulk was defined only by the section of the ducts which connect the two envelopes) can be exploited to house for example internal mechanical reinforcements of the tunnel, for example. And it is compact enough to occupy only part of the length of the tunnel available, which makes it possible to consider also housing in the tunnel other organs, such as gas tanks or electrical machines.

The invention also relates to any motor vehicle, comprising the body structure described above, and a heat engine associated with another propulsion mode such as an electric machine, a hydraulic motor, or a hybrid thermal-pneumatic motor. or an engine running on gaseous fuel.

Other advantages and features of the invention will become apparent from the following description of several embodiments of the invention, given by way of non-limiting examples, with reference to the following figures:

- Figure 1 shows in perspective a first example of silencer according to the invention;

- Figure 2 shows a longitudinal section of the silencer according to Figure 1;

- Figure 3 shows the acoustic diagram corresponding to the silencer of Figures 1 and 2;

- Figure 4 is a bottom view of a vehicle body structure tunnel portion, housing the silencer according to Figures 1 and 2;

- Figures 5,6 and 7 are longitudinal sections of variants of the silencer according to the first example shown in Figures 1, 2, 3. These figures are schematic, and do not necessarily respect the scale. From one figure to another, the same references correspond to the same components.

FIG. 1 and FIG. 2 represent a first example of a silencer S according to the invention integrated in an exhaust line L of a heat engine M of a hybrid vehicle having another means of non-thermal propulsion, and these two figures will be described jointly. The arrow F indicates the direction general flow of the exhaust gas from the engine M, the terms "upstream" and "downstream" referring to said general direction of flow. The silencer according to the invention incorporates what is generally referred to in the field of mufflers under the terms of intermediate silencer and rear silencer. Naturally, the invention is not limited to an application to hybrid vehicles, and is also advantageously applicable for vehicles only equipped with a heat engine.

The silencer S according to this example 1 comprises two envelopes: an upstream envelope E1 and a downstream envelope E2, both substantially aligned and arranged along the longitudinal axis X of the vehicle. The upstream envelope E1 comprises a side wall 5 which defines a substantially parallelepipedal volume, and which is closed at its transverse ends (along the transverse Y axis, perpendicular to the X axis) by upstream end transverse partitions 3 and downstream 4, also called cups. The Z axis is the vertical. The downstream envelope E2 is disposed at a distance from the upstream envelope E1, it has a substantially frustoconical cross section. It comprises a side wall 6 and transverse end bulkheads or cups upstream 7 and downstream 8 and defines a volume 2. For mechanical strength issues, an intermediate cup strongly perforated and without acoustic role can be installed to maintain the end of the tubes "go" and "return" in the middle of the envelope E2.

The upstream envelope E1 is partitioned by an intermediate partition 9, so as to define an upstream volume 1a and an intermediate volume 1b.

The envelopes E1, E2 of the silencer thus define three volumes: the volume 1a and the volume 1b intermediate of the upstream envelope E1, and the volume 2 of the downstream envelope E2.

The silencer S comprises a supply duct 10 in exhaust gas, which is connected upstream to the exhaust line L, and which opens into the volume 1b through the volume 1 through the cup 3 Then 9. The duct portion 10 in the volume 1b is provided with perforations January 1 distributed throughout its substantially cylindrical periphery.

This duct 10 is extended by a conduit "go" 12 which passes through the downstream cup 4 of the upstream envelope E1 and which then passes through the downstream envelope E2 through an opening in its upstream end wall 7. It opens out inside the volume 2 of the downstream envelope E2 at approximately half of its length.

The muffler also comprises two conduits "return" 13,13 ', arranged side by side, parallel to the longitudinal axis X, and under the conduit "go" 12. They open, downstream side, in the volume 2 of the downstream envelope E2 about half or two thirds of its length, in a similar way to the conduit 12. They open, upstream side, in the upstream volume 1a of the upstream envelope E1 (approximately half or third) the length of the volume 1 a), through the volume 1 b and the intermediate partition 9. They therefore cross the intermediate partition 9 and the downstream partition 4 of the upstream envelope E1 and the upstream partition 4 of the downstream envelope E2 through openings in them.

Finally, the silencer S has two exhaust ducts 14,14 ', arranged symmetrically on either side of the envelopes E1, E2. They open at their first ends in the volume 1a of the upstream envelope E1 through an opening in the partition 3. (They may extend or not in said volume 1a, without crossing the intermediate partition 9). The partition 3 is thus provided with two symmetrical openings for these evacuation conduits, and with an opening for the supply duct 10. In the example shown, the openings for the evacuation ducts 14, 14 'are at above the opening for the supply duct 10. The ducts 14, 14 'make an elbow at the outlet of the partition 3 and along each side the upstream envelope E1 then at least a portion of the downstream envelope E2 , to open on either side of the downstream envelope E2 approximately in the middle of its length. They can also open upstream, or at the level of the cup 8 or beyond. The ducts 10, 12,13,13 ', 14,14' are here all cylindrical, but their section could be of different shape, oval for example. Here, the section of conduits 10 and 12 is greater than that of each of the other conduits 13, 13 ', 14, 14', and this, in order to maintain substantially constant passage sections throughout the path of the gases. Other dimensional or positioning choices or number of conduits can be made while remaining within the scope of the invention. Thus, one could choose to replace the two intermediate conduits 13,13 'by one. Similarly, one can use only one exhaust duct, with a larger section, to be able to evacuate the exhaust with the same loss of load. It is also possible to position the supply duct 10 and / or the "go" duct 12 below the ducts 13, 13 'and / or the evacuation ducts 14, 14' above the duct 10 or the duct. 12. The duct 10 and / or the "go" duct 12 could also be split. It is also possible to make only one duct of the ducts 10 and 12. The section of the evacuation duct 14 (or the sum sections of the ducts 14 and 14 'when they are two) may be greater than that of the supply ducts, "go" and "return" 10,12,13, in order to reduce the speed of the gases and therefore the blast noise associated.

It has been indicated that the duct 12 is in the extension of the duct 1, beyond the perforations January 1 which is provided with the conduit 10 supply. Different variants are possible: the two ducts can be one. They can be attached to each other by any known technique (welding ...) by direct contact or at a distance from each other.

The path of the exhaust gas in the silencer is more particularly illustrated in Figure 2: the gases enter the silencer S by the supply duct 10 in a direction represented by the arrow f1, then follow the duct " 12 are arranged in the extension of the conduit 10. They therefore cross the volume 1a and open into the volume 1b in the conduit 10, and the conduit 12 brings them into the volume 2 of the downstream envelope E2 along a first path " to go ". Then, as indicated by the arrow f2, they start in the opposite direction, according to a second path "return" in the conduits "return" 13,13 'arranged above the ducts 10 and 12 in a direction represented by the arrow f3 and open into the volume 1 a of the upstream envelope E1. From there, they are evacuated via the evacuation ducts 14, 14 ', starting again along a third "go" path (arrow f4) to exit at the end of the ducts 14, 14' in the direction symbolized by the arrow f5, of the same orientation as the direction f 1 with which the gases had entered the silencer S.

It should be noted that there is provided a seal between the openings in the cups and the outer periphery of the conduits which pass through them, especially at least one of the end cups 4.7 which are opposite. However, it is possible to provide, for the ducts 12, 13, 13 ', either at the level of the cup 4 or at the level of the cup 7, a non-perfect seal, which allows the casing and ducts assembly to undergo slight dimensional changes in use, especially due to thermal expansion, without the whole is too mechanically stressed.

It is therefore seen that in this example, it is the ducts 12, 13, 13 'which ensure the mechanical joining of the upstream envelopes E1 and downstream E2 between them.

We also see that the shape of the envelopes can vary, and will adapt flexibly both to the size of the conduits that must pass through, but also to the environment of the exhaust line. Here, the silencer is located in the tunnel of a vehicle underbody, and the zone between the two envelopes, less congested, of the silencer will be able to be, in the tunnel, exploited for example so that the ceiling or the sides Tunnel interiors accommodate mechanical reinforcements.

Different processes can be used to manufacture the envelopes and muffler ducts, which are metal: one can use the stamping technique, or the so-called "rolled-crimped" technique.

Figure 3 shows the acoustic diagram of the silencer according to the invention, with the usual conventions of this type of representation. It is optimal when the total volume corresponding to 1 a + 1 b + 2 is divided in three according to the approximate distribution where the volume 1 a is about 3 liters, the volume 1 b about 3 liters also, and the volume 2 of about 6 liters, thus preferably having the relationship 1a substantially equal to 1b and 2 greater than 1a and 1b and corresponding approximately to the sum 1a + 1b. Here, the ducts 12, 13 and 13 ', 14 and 14' are organized in such a way that their lengths increase when the flow of exhaust gas is followed: the length of the duct "to go" 12 is lower than that of the "return" pipes 13, 13 ', themselves lower than those of the exhaust ducts 14, 14'. This distribution makes it possible to obtain resonance frequencies of the Helmholtz resonators resulting from the coupling of the ducts (masses) and volumes (stiffness) given, with the duct lengths 12, 13 and 13 ', 14 and 14' minimum for a section given. The volume is thus maximally used for the desired function of the noise filtering by these volumes, above the selected resonant frequencies. This organization of volumes and ducts makes it possible to significantly separate the three associated Helmholtz resonance frequencies, allowing the cumulation of the filtering effects of each of the resonators, thus providing a high level of acoustic performance. Nevertheless, the highest Helmholtz resonance frequency must remain lower than the first acoustic resonance of the exhaust duct 14 (first acoustic mode of the open-open duct).

This architecture is particularly favorable when the silencer is intended to be housed at least partly in the tunnel of the vehicle body, because the volume available under the tunnel is extended, as the general form of the silencer of the invention. It can be seen in FIG. 4, which shows a vehicle body structure C seen from below at its tunnel T, with the silencer S of example 1 housed in the tunnel (the downstream envelope E2 is truncated in FIG. its most downstream part, and simplified representation to be clearer).

Figures 5 to 7 are variants of Example 1: Figure 5 corresponds to an example 2 which differs from Example 1 in that the volumes 1 a, 1 b and 2 are distributed differently in both envelopes. Here, the upstream envelope E1 'delimits only the upstream volume 1a, and the larger downstream envelope E2' delimits the intermediate volumes 1b and downstream 2. It is therefore the downstream envelope E2 'which has the intermediate partition 9 to partition it in two.

FIG. 6 corresponds to an example 3, which differs from example 1 in that the volumes 1 a, 1 b and 2 are delimited by a single envelope E. This single envelope E then has two intermediate partitions 9 and 9 'which divide it into three. Figure 7 corresponds to an example 4, which differs from Example 1 in that the volumes 1a, 1b and 2 are each delimited by an envelope E1 ", E2" and E3.

It is seen from these various examples that the invention has defined an acoustic scheme for great flexibility of realization, which allows to adapt the external dimensioning of the silencer to environments, including tunnel, varied. The particularity of the path of the exhaust gases that make a return trip in the ducts passing through the envelope or envelopes, then a final one-way trip through the out-of-envelope exhaust ducts contributes to this flexibility, and, overall, to a remarkable compactness. of the muffler given the acoustic performance provided by its acoustic scheme.

Claims

1. Silencer (S) intended to equip an exhaust line (L) of a heat engine (M), characterized in that it comprises one or more envelopes (s) which delimits (s) three volumes (1 a , 1b, 2), said upstream (1a), intermediate (1b) and downstream (2), arranged successively and traversed by a plurality of conduits, including: - a supply duct (10) bringing the gases of exhaust from the engine (M) into the intermediate volume (1b) through the upstream volume (1a), - a so-called "go" path (12) leading the exhaust gases from the intermediate volume (1 b) in the downstream volume (2), a so-called "return" path (13) leading the exhaust gases from the downstream volume (2) to the upstream volume (1 a) while passing through the intermediate volume (1 b), and - an exhaust duct (14, 14 ') disposed predominantly outside the envelope or envelopes and opening upstream volume (1 a).

2. Silencer according to the preceding claim, characterized in that the three volumes (1 a, 1 b, 2) are distributed in one, two or three envelopes.

3. Silencer according to one of the preceding claims, characterized in that the volumes are distributed in several envelopes delimited by side walls and transverse end walls called cups, said envelopes being connected to each other by the minus two ducts passing through at least two cups opposite two successive envelopes.

4. Silencer (S) according to the preceding claim, characterized in that the discharge duct (14,14 ') runs along the upstream volume (1a) of the silencer, and possibly also the intermediate volume (1b) and possibly also also the downstream volume (2) over at least part of their length.

5. Silencer (S) according to one of the preceding claims, characterized in that the discharge duct (14,14 ') opens out of the upstream cup (3) of the casing defining the upstream volume (1 a) of quiet.

6. Silencer (S) according to one of the preceding claims, characterized in that it comprises several, including two exhaust ducts (14,14 '), in particular parallel to each other over at least a portion of their lengths.

7. Silencer (S) according to one of the preceding claims, characterized in that it comprises several, including two, path paths "go" (12,12 '), and / or more, including two path ducts. "Back" (13,13 ').

8. Silencer (S) according to one of the preceding claims, characterized in that the intermediate volume (1b) is substantially equal to or adjacent to the downstream volume (2).

9. Silencer (S) according to one of the preceding claims, characterized in that the upstream volume (1 a) is substantially twice as large as the intermediate volume (1 b) and / or the downstream volume (2).

Silencer (S) according to one of the preceding claims, characterized in that the so-called "go" path duct (12) is of a length (L1) less than that (L2) of the said path duct. back "(13), itself shorter than the length (L3) of the exhaust duct (14,14 ').