WO2015028727A1

WO2015028727A1 - Silencer intended to be fitted to an exhaust line of a heat engine

Info

Publication number: WO2015028727A1
Application number: PCT/FR2014/051521
Authority: WO
Inventors: Laurent Gagliardini; Philippe VANNIER; Michel Caruel; Cedric DUMONT
Original assignee: Technoboost
Priority date: 2013-08-29
Filing date: 2014-06-19
Publication date: 2015-03-05
Also published as: CN105556074A; EP3039257B1; EP3039257A1; FR3010136B1; FR3010136A1

Abstract

The invention concerns a silencer (S1) intended to be fitted to an exhaust line (L) of a heat engine (M), and that comprises one or a plurality of envelope(s) that delimit three volumes (1 a,1 b, 2), referred to as upstream (1 a), intermediate (1 b) and downstream (2), traversed by a plurality of conduits, including: - a supply conduit (10) conveying the exhaust gases from the engine (M) to the intermediate volume (1b), passing through the upstream volume (1 a), - a so-called "outward" journey conduit (12) taking the exhaust gases from the intermediate volume (1 b) to the downstream volume (2), - a so-called "return" journey conduit (13) taking the exhaust gases from the downstream volume (2) towards the upstream volume (1 a), passing through the intermediate volume (1 b), and - a discharge conduit (14) taking the exhaust gases out of the silencer, either by means of a so-called "outward" journey from the upstream volume (1 a) to the downstream volume (2) from which it opens to the outside, or by means of a so-called "outward-return" journey from the upstream volume (1 a) to the downstream volume (2) and then once more to the upstream volume (1 a) from which it opens to the outside.

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 makes the exhaust gas circulate under the body 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 closer the ears of the occupants.

The invention relates to a silencer intended to equip an exhaust line of a heat engine, and which comprises one or more envelope (s) which delimits (s) three so-called upstream volumes, intermediate and downstream, arranged successively and traversed by a plurality of ducts, of which:

a supply duct bringing the exhaust gases from the engine into the intermediate volume through the upstream volume,

a so-called "go" path leading the exhaust gases from the intermediate volume to the downstream volume, a "return" path conduit leading the exhaust gases from the downstream volume to the upstream volume while passing through the intermediate volume, and

an exhaust duct leading the exhaust gases out of the silencer, or by a path called "go" from the upstream volume to the downstream volume from which it opens outwards,

or by a so-called "round trip" path from the upstream volume to the downstream volume and then back to the upstream volume from which it opens outwards. The term "upstream" and "downstream" is understood throughout the present text with reference to the general direction of flow 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. All the present text includes "low", "high" and "vertical" spatial positioning indications such as the indications relating to the positioning of the muffler once mounted in the vehicle, itself positioned at a standstill. horizontal plane.

The silencer according to the invention therefore has the particularity of implanting the acoustic scheme of the silencer with at least three separate volumes, connected by conduits that provide the guidance of the exhaust gas inside these volumes.

[0009] Preferably, the evacuation duct can define a so-called "round-trip" path by presenting a bend in the downstream volume: in this configuration, the exhaust gases enter the evacuation duct in the upstream volume. and remain guided in the conduit to lead directly to the outside of the silencer at the same volume upstream.

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

[ooi i] With the multi-envelope embodiment, 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 coherence of the assembly without having to foresee (in any case more compulsorily) specific mechanical means to maintain correct relative positioning of the envelopes relative to each other

According to one embodiment, the volumes of the silencer are distributed in several envelopes defined by side walls and transverse end walls called cups, said envelopes being connected to one another by at least two through ducts. at least two cups next to two successive envelopes.

According to one variant, the evacuation duct opens up from the upstream cup of the envelope defining the upstream volume of the silencer (configuration with the so-called "round-trip" path of the evacuation duct) or from the downstream cup of the silencer. downstream volume of the silencer (configuration with the path "go" of the exhaust duct). This variant is particularly suitable when the muffler is intended to be oriented substantially along the longitudinal axis of the vehicle, and for example at least partially housed in the tunnel of the vehicle body.

According to another variant, the evacuation duct opens the transverse wall of the envelope defining the upstream volume of the silencer (configuration with the so-called "round-trip" path of the exhaust duct) or the transverse partition. downstream of the silencer downstream volume (configuration with the "go" path of the exhaust duct). This variant is particularly suitable in the case where the silencer is in transverse position, that is to say disposed perpendicular to the longitudinal axis of the vehicle, to facilitate the connection of the silencer to the rest of the exhaust line in part swallows.

Naturally, this same type of connection can be provided between the silencer and the exhaust line in the upstream portion, the supply duct can thus enter the upstream volume not by its upstream cup but through its side wall .

[0016] Still if the muffler is mounted in a transverse configuration, it is also possible to maintain arrivals of the supply and evacuation conduits via the cups, in a more conventional manner, by bending the outgoing ducts of the ducts. volumes to allow the connection with the exhaust line which can, she, usually have an orientation along the longitudinal axis of the vehicle.

The silencer according to the invention may comprise several, in particular two, "go" and / or several path conduits, in particular two, "return" path conduits, and / or several, in particular two, evacuation conduits, in particular parallel to each other over at least part of their lengths.

It can indeed split each of the ducts of the silencer, in particular to give more flexibility in the sizing of the silencer as a whole. The ducts thus split will advantageously have a smaller section than a unit duct, so as to keep the same pipe capacity gas flow rate given, and keep a similar pressure drop.

Advantageously, the silencer according to the invention has its intermediate volume substantially equal to or adjacent to the downstream volume.

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

According to a preferred embodiment, the silencer according to the invention has a so-called "go" path duct of a length less than that of the so-called "return" path duct, itself of shorter length than the exhaust duct. 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. As already mentioned, the silencer can also be provided for transverse implantation in the vehicle.

Optionally, the envelope, or at least one of the envelopes in the case where there are several, may be doubled, preferably internally, a soundproofing layer of a material supporting high temperatures. It may for example be glass wool or rock wool.

A great advantage of the silencer according to the invention is that it can easily be arranged in the tunnel (in its longitudinal implantation). The space between the two envelopes, in the configuration with several envelopes, which, in fact, makes in this area 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 accommodate for example internal mechanical reinforcements of the tunnel, for example. And it is compact enough to occupy only a part of the length of the available tunnel, 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 has a longitudinal section of a first example of silencer according to the invention;

- Figure 2 shows a longitudinal section of a second example of silencer according to the invention; FIG. 3 shows a perspective view of a third example of a silencer according to the invention;

FIG. 4 represents the acoustic diagram corresponding to the silencers of the preceding figures. These figures are schematic, and do not necessarily respect the scale. From one figure to another, the same references correspond to the same components.

Figures 1, 2 and 3 show examples of silencers - respectively referenced S1, S2 and S3 - according to the invention integrated in an exhaust line L of a heat engine M of a hybrid vehicle having another non-thermal propulsion means. The arrow F indicates the general flow direction of the exhaust gases from the engine M, the terms "upstream" and "downstream" referring to said general direction of flow. These examples of silencers according to the invention incorporate what is generally referred to in the field of mufflers under the terms of intermediate silencer and rear silencer. Various methods can be used to manufacture the envelopes and ducts of the examples of silencers, described below, which are made of metal: one can use the technique of stamping, or the so-called "rolled-crimped" technique.

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.

Figure 1 shows a first example of silencer S1 which comprises two envelopes: an upstream envelope E1 and a downstream envelope E2, both substantially aligned and arranged along the longitudinal axis of the vehicle. The upstream envelope E1 comprises a lateral wall which defines a so-called upstream volume 1a substantially parallelepipedic, and which is closed at its transverse ends by transverse partitions 3 upstream end and downstream 4, also called cups. The envelopes define a substantially parallelepipedal volume, with a substantially rectangular or square section, here slightly frustoconical. Alternatively, their section can be circular for define a cylindrical volume, or be oval or have another shape, as long as the envelope in question defines an elongated geometric shape for accommodating conduits.

The downstream envelope E2 is disposed at a distance from the upstream envelope E1. It comprises a lateral wall and transverse end partitions or cups upstream 7 and downstream 8. It is partitioned by an intermediate partition 9, so as to define an intermediate volume 1b and a downstream volume 2.

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

For mechanical strength, an optional intermediate cup strongly perforated and without acoustic role can be installed to maintain the end of the tubes "go" and "return" (described later) in the middle of the envelope E1 . The silencer S1 comprises a supply duct 10 of exhaust gas, which is connected upstream to the exhaust line L, and which opens into the volume 1b through the volume 1a by the cup 3 then the cup 4 of the envelope E1 and the upstream cup 7 of the envelope E2. The portion of duct 10 in volume 1b is provided with perforations January 1 distributed over its substantially cylindrical periphery.

This duct 10 is extended by a conduit "go" 12 which passes through the intermediate cup 9 to open inside the volume 2 of the downstream envelope E2, approximately half (between one-third and two-thirds) the length of the volume 2. [0037] The silencer also comprises a conduit "return" 13 under the conduit "go" 12. It opens, downstream side, in the volume 2 of the downstream envelope E2 about half (between one-third and two-thirds of the length of the volume 2), in a manner similar to the conduit 12. It opens, upstream side, in the upstream volume 1a of the upstream envelope E1 to approximately half (between the third and the two third), the length of the volume 1a, passing through the intermediate partition 9, the intermediate volume 1b and then the cups 7 and 4.

Finally, the silencer S1 comprises a discharge duct 14, which opens, upstream side approximately to half (between the third and two thirds), the length of the volume 1a of the upstream envelope E1 and side downstream outside the downstream casing E2, passing through the cups 4, 7, 9 and 8 successively.

Where it is stated in the present description that ducts pass through walls, here, in this case cups, it means that the walls / cups have, prior to their assembly, been provided with orifices for the insertion of conduits in question. Depending on the case, the mounting may be forced or around the orifices provided with sealing means to preserve the tightness of the envelope, (especially at least one of the end cups 4, 7 which are facing) or the assembly may leave a certain clearance between the conduit and the orifice to allow a certain movement between the conduit and the wall / the cup through which it passes, which allows the whole envelopes and conduits to know slight dimensional changes in use, especially due to thermal expansion, without the whole is too mechanically stressed.

The ducts 10,12,13,14 are here all cylindrical, but their section may be of different shape, oval for example. Here, the section of the ducts 10 and 12 is identical to that of the ducts 13 and 14, in order to maintain substantially constant passage sections all along the path of the gases.

Other dimensional or positioning choices or number of ducts can be made while remaining within the scope of the invention.

Thus, one could choose to split one or more of the supply ducts 10, "go" 12, "return" 13 and evacuation 14. In this case, the section of the split ducts is reduced by the same amount to keep the same total section.

The section of the exhaust duct 14 (or the sum of the sections of the exhaust ducts when they are two) may also be greater than that of supply ducts, "go" and "return" 10,12,13, in order to reduce the speed of the gases and therefore the associated blast sound.

It has been indicated that the conduit 12 is in the extension of the duct 10, 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 flow of exhaust gas in the silencer S1 is as follows: the gases enter the silencer S1 by the supply duct 10 in a direction represented by the arrow f1, then follow the conduit "go" 12 disposed 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 "go". Then, as indicated by the arrow f2, they start in the opposite direction, according to a second path "return" in the conduit "return" 13 substantially parallel to the conduits 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 duct 14 by starting again (arrow f4) along a third "go" path (arrow f4) to exit at the end of the duct 14 out of the downstream casing E2, depending on the direction symbolized by the arrow f5, of the same orientation as the direction f 1 with which the gases were entered in the silencer S1.

In this example, it is the conduits 12, 13 which ensure the mechanical attachment 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 S1 is housed in the tunnel of a vehicle underbody, and the zone between the two envelopes, less congested, the silencer will be able, in the tunnel, exploited for example so that the ceiling or the inner sides of the tunnel accommodate mechanical reinforcements. Figure 2 shows a second example of silencer S2 which is a variant of the first example. Other things being equal, the silencer S2 has two differences compared to the silencer S1.

On the one hand, here, the volumes 1a, 1b and 2 are delimited by a single envelope E. This single envelope E then has two intermediate partitions 9 and 9 'which partition it into three.

On the other hand, the shape of the exhaust duct 14 'is different, having a bend at the volume 2, so that the exhaust gases are guided by the duct from the volume 1a to the volume 2 in a forward path (arrow f6), then from the volume 2 to the volume 1 a again (arrow f7), the conduit 14 'opening out of the envelope E through the cup 3. In this configuration it can be seen that the exhaust gases exit the silencer S1 in a direction (f7) opposite to that (f1) with which the gases enter the silencer S2. Figure 3 shows the third example S3 silencer which is a variant of the silencer S2. The noticeable difference from the S2 muffler lies in the way the exhaust gases enter the muffler. Here, the silencer is not intended to be disposed along the longitudinal axis of the vehicle, but along its transverse axis. We are talking about transverse implantation. The upstream part of the exhaust line L to which the silencer S3 must be connected remains orientated along the longitudinal axis of the vehicle. The most upstream portion of the supply duct 10 is thus bent in the volume 1a, so that the gases coming from the exhaust line along the longitudinal axis can be guided to take a 90 ° orientation ( arrow f1 '). In this case, the conduit 10 passes through the envelope E not through its upstream cup but through its side wall, near its upstream end, through an opening made for this purpose. Alternatively, it is possible to envisage a connection via the upstream cup 3, the bend of the conduit 10 then being provided outside the envelope E. The outlet of the discharge conduit 14 out of the envelope E is through the upstream cup 3, and has a bend outside the casing to allow connection downstream to the exhaust line (arrow f8 '). Figure 4 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 b is about 3 liters, the volume 2 about 3 liters also, and the volume 1 is approximately 6 liters, with the relationship 2 preferably substantially equal to 1 b, and 1 a greater than 2 and 1 b and corresponding approximately to the sum 2 + 1 b.

Here, the ducts 12, 13 and 14 are organized in such a way that their lengths increase when the flow of exhaust gas is followed: the length of the "go" duct 12 is smaller than that of ducts. "Return" 13, itself lower than that of the exhaust duct 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 14 minimum for a given section. 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).

It is seen from these various examples that the invention has defined an acoustic scheme for great flexibility of implementation, 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 last outward or return trip through the evacuation ducts contributes to this flexibility, and, overall, to a remarkable compactness of the muffler given the acoustic performance provided by its acoustic scheme.

Claims

Silencer (S1, S2, S3) 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 ( 1a, 1b, 2), said upstream (1a), intermediate (1b) and downstream (2), arranged successively and traversed by a plurality of ducts, including: - a supply duct (10) bringing the exhaust gas from the engine (M) in the intermediate volume (1b) through the upstream volume (1a), - a so-called "go" path (12) conducting the exhaust gases from the intermediate volume (1b) in the downstream volume (2), a so-called "return" path (13) conducting the exhaust gases from the downstream volume (2) to the upstream volume (1a) while passing through the intermediate volume (1b), and - an exhaust duct (14) driving the exhaust gas out of the silencer, or by a path called "go" from the upstream volume (1a) to the downstream volume (2) of or it opens outwards, either by a so-called "round-trip" trip from the upstream volume (1 a) to the downstream volume (2) and then again to the upstream volume (1 a) from which it flows towards the 'outside.

Silencer (S1, S2, S3) according to the preceding claim, characterized in that the discharge duct (14) defines a so-called "round-trip" path by presenting a bend in the downstream volume (2).

Silencer (S1, S2, S3) according to one of the preceding claims, characterized in that the three volumes (1 a, 1 b, 2) are distributed in one, two or three envelopes.

Silencer (S1, S2, S3) according to one of the preceding claims, characterized in that the three volumes (1 a, 1 b, 2) are distributed in several envelopes (E1, E2) delimited by side walls and partitions transverse end of said cups (3,4,7,8), said envelopes being connected to each other by at least two ducts passing through at least two cups facing two successive envelopes.

5. Silencer (S1, S2, S3) according to the preceding claim, characterized in that the discharge duct (14) opens out of the upstream cup (3) of the casing defining the upstream volume (1 a) of the silencer or the downstream cup (8) of the downstream volume (2) of the silencer. Silencer (S1, S2, S3) according to one of the preceding claims, characterized in that it comprises a plurality of, in particular two, "go" path ducts (12), and / or several, in particular two, ducts of "return" path (13), and / or more, in particular two, exhaust ducts (14, 14 '), in particular parallel to each other over at least a portion of their lengths. 7. Silencer (S1, S2, S3) 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).

Silencer (S1, S2, S3) 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 (S1, S2, S3) according to one of the preceding claims, characterized in that the so-called "go" path duct (12) is of a length less than that of the "return" path duct ( 13), itself less than the length of the exhaust duct (14).