GB2611178A

GB2611178A - Exhaust silencer

Info

Publication number: GB2611178A
Application number: GB2212296.4A
Authority: GB
Inventors: Reisinger Gerd
Original assignee: Remus Innovation GmbH
Current assignee: Remus Innovation GmbH
Priority date: 2021-09-13
Filing date: 2022-08-24
Publication date: 2023-03-29
Also published as: GB202212296D0; CN115807703A; DE102021123653A1

Abstract

An exhaust silencer for an internal combustion engine with flow-guiding built-in components arranged in a functional (gas flow) space delimited by an outer wall comprising first 2 and second 3 casing pipes comprising a flap 32 arrangement with a flow guide 14 and a bypass 29 arrangement fluidically connected in parallel with the flow guide. The flow path thereof comprises four spiral helical channels (21, 22, 27 and 28) through which a flow can pass in series, in the direction opposing the main gas flow in channels 1 and 3, and in the direction of the main gas flow in channels 2 and 4, via two deflection zones and a transition zone and are fluidically connected to the inflow pipe 4 via passage 24, and the outflow pipe 5 via passage 35 respectively.

Description

EXHAUST SILENCER

The present invention relates, as indicated in the preamble of claim 1, to an exhaust silencer for an internal combustion engine, comprising a functional space which is delimited by an outer wall and has an exhaust inlet, an exhaust outlet and flow-conducting built-in components, wherein the flow-conducting built-in components comprise at least one flap arrangement with a flow guide which is connected to an inflow pipe communicating with the exhaust inlet and to an outflow pipe communicating with the exhaust outlet, and an adjustable flap associated with the flow guide and serving to vary the free flow cross-section of the flow guide, and wherein, furthermore, a flow can pass through a bypass arrangement existing in fluidic parallel connection to the flow guide of the flap arrangement in dependence on the momentarily free flow cross-section of the flow guide.

Exhaust silencers of the generic type, in which the operating behavior, namely the flow through the built-in components and thus the silencing behavior, can be influenced by means of a flap arrangement, are known and used in various different configurations. As far as the flap arrangement in particular is concerned, depending on the individual design, the flap can be used to close the flow guide of the flap arrangement and open it (if necessary to different flow cross-sections) or the flap, depending on its current position, changes only the flow cross-section of the flow guide, without the possibility of (completely) closing the flow guide. Thus, it is necessary to differentiate whether the adjustment of the flap is done passively, i.e., automatically (e.g., by the pressure conditions existing at the flap itself), or actively by means of an actuator that acts on the flap and is operated with external energy and is possibly actuated via a control system.

Regarding the prior art in the field of generic exhaust silencers, reference is to be made, for example, to US 7,896,130 B2, US 8,201,660 B2, NO 2010/135095 Al, US 8,468,813 B2, NO 2016/111326 Al, US 10,518,632 B2, US 10,788,136 Bl, and US 2019/0360374 Al.

In practice, exhaust silencers for internal combustion engines are subject to various requirements, some of which conflict with each other. These generally include -at least in the case of a defined flap position -broadband silencing behavior, i.e. good silencing extending over a comparatively large operating range of the respective internal combustion engine, small dimensions, low flow losses and thus low backpressure, low weight, durability and low production costs. In many cases, the additional aim is to be able to implement individual manufacturer-and/or vehicle-specific sound characteristics with little or no additional expense.

The present invention has the object of providing an exhaust silencer of the generic type which is particularly practical within the above meaning, wherein of the various requirements (see above), the smallest possible dimensions and/or a particularly compact design are considered to be particularly important.

The object described is achieved in that in a silencer of the generic type described, the bypass arrangement comprises a flow path with a helical first spiral channel, which is fluidically connected to the inflow pipe via a first passage arranged adjacent to the flap arrangement, a helical second spiral channel, which is fluidically connected to the first spiral channel in the region of a first deflection zone and through which a flow can pass in the opposite direction to the exhaust flow in the first spiral channel, a helical third spiral channel which is fluidically connected to the second spiral channel in the region of a transition zone, and a helical fourth spiral channel which is fluidically connected to the third spiral channel in the region of a second deflection zone and through which a flow can pass in the opposite direction to the exhaust flow in the third spiral channel and which is fluidically connected to the outflow pipe via a second passage arranged adjacent to the flap arrangement.

In this manner it is possible to implement generic exhaust silencers that have particularly small dimensions and are thus very compact, while maintaining high efficiency. However, the advantages achievable with the invention are by no means limited thereto. On the contrary: the present invention also proves to be very advantageous from various other points of view. For example, if the invention is suitably implemented, the respective exhaust silencers can be produced at particularly low cost. This is also supported by the fact that the design according to the invention is suitable to a particularly significant extent for a modular concept in the sense that, when otherwise identical components are used, it is already possible to adapt the exhaust silencer to different requirements (e.g. different engine series of the same vehicle type) by modifying individual components. Furthermore, the present invention can be implemented in a wide range of -4 -applications in that the respective concept is suitable both for flap arrangements with a passively adjusting flap and for flap arrangements with a flap which can be actively adjusted by means of an actuator. Specifically, the variant mentioned in second place is particularly favorable with regard to the practical requirements, because it allows active individual modification of the sound characteristics during operation of the respective vehicle. This applies, as will be further expressed below, in a very special way in the case in which the actuator is designed for a proportional flap adjustment, which can in particular also include a control-related feedback of a signal, which represents the actual position of the actuator or the flap actuated by the latter, into a control system.

Through comparative tests it was possible to determine that the extremely advantageous operating behavior of the exhaust silencer according to the invention -in synergistic interaction with the four-way spiral flow enabling a particularly long flow path -is due, among other things, to the helpful contribution of the multiple dedicated flow deflections, i.e. in addition to the flow deflections in the first and second deflection zones, the deflections when flowing through the first and second passages. Depending on the individual boundary conditions, a fifth dedicated flow deflection (see below) between the second and third spiral channels may prove to be favorable.

As far as the geometry of the spiral channels is concerned, according to a first preferred refinement of the invention geared towards typical internal combustion engines, the pitch of the first and second spiral channels is between 1 time and 6 times the inner diameter of the inflow pipe. In a corresponding manner, the pitch of the third and the fourth spiral channels is preferably between 1 time and 6 times the inner diameter of the outflow pipe. Particularly preferably, the pitch of the first and second spiral channels is between 1.5 times and 4 times, most preferably between 2 times and 3 times, the inner diameter of the inflow pipe; and the pitch of the third and fourth spiral channels is particularly preferably between 1.5 times and 4 times, most preferably between 2 times and 3 times the inner diameter of the outflow pipe.

The above design rules prove to be particularly advantageous, in particular in connection with other design rules relevant for the geometric situation and the flow conditions within the exhaust silencer. In this sense, the first and second spiral channels and/or the third and fourth spiral channels each preferably extend over a screwing angle of between 180° and 720°, particularly preferably between 225° and 630°, most preferably between 270° and 540°.

With regard to a particularly favorable flow situation for the acoustic effect, according to yet another preferred refinement of the invention, the first passage is delimited by an oblique partial cut end of the inflow pipe and/or the second passage is limited by an oblique partial cut end of the outflow pipe. This refinement is also characterized by a particularly simple producibility of the corresponding exhaust silencer.

In the context of the present invention, the first and second spiral channels can be radially offset from one another, i.e. defined by helical lines having different diameters, in particular by one of the two spiral channels surrounding the other, inner one, radially on the outside; in other words, in this configuration, the first and second spiral channels run with different radii in two different annular spaces, e.g., concentrically surrounding the inflow pipe. The same applies to the pair of third and fourth spiral channels. Especially from the point of view of size, however, another configuration is particularly advantageous, namely in that the first and second spiral channels are separated from one another by a primary helix insert and run with the identical radius in the same primary annular space formed radially on the outside by a primary casing pipe and/or the third and fourth spiral channels are separated from one another by a secondary helix insert and run with the identical radius in the same secondary annular space formed radially on the outside by a secondary casing pipe. Here, the first and second spiral flows or the third and fourth spiral flows are virtually screwed into each other in each case in pairs in opposite directions. The first and the second spiral flow -with respect to their axis and their axial flow component determined along this axis -show the corresponding direction of rotation or screwing in the sense of a right-hand or a left-hand screwing. The same applies to the pair of third and fourth spiral flows. Thus, in the region of the first and second deflection zones, respectively, this results in a particularly efficient 1800 flow deflection with regard to silencing.

The cross-sectional area of the primary annular space is preferably between 1.5 times and 4.5 times, particularly preferably between 2 times and 4 times, most preferably between 2.5 times and 3.5 times the cross-sectional area of the inflow pipe; and, in a corresponding manner, the cross-sectional area of the secondary annular space is preferably between 1.5 times and 4.5 times, particularly preferably between 2 times and 4 times, most preferably between 2.5 times and 3.5 times the cross-sectional area of the outflow pipe. Such dimensions prove to be particularly advantageous in terms of very good silencing behavior even with a comparatively compact design of the exhaust silencer and low flow losses, i.e. comparatively low backpressure.

According to another design rule, it proves favorable if the cross-sectional area of the first spiral channel and of _ 7 _ the second spiral channel determined perpendicular to the respective spiral guide line, i.e., the cross-sectional area of the first and the second spiral channel, respectively, in a plane oriented perpendicular to the direction of the screwing line at the respective center of the area is between 0.2 times and 2 times, preferably between 0.4 times and 1.5 times, and particularly preferably between 0.6 times and 1.0 times the cross-sectional area of the inflow pipe. In a corresponding manner, the cross-sectional area of the third spiral channel and the fourth spiral channel determined perpendicular to the respective spiral guide line is preferably between 0.2 times and 2 times, particularly preferably between 0.4 times and 1.5 times, and most preferably between 0.6 times and 1.0 times the cross-sectional area of the outflow pipe.

The primary and/or secondary casing pipe explained above, which delimits the primary or secondary annular space radially on the outside, preferably forms part of the outer wall delimiting the functional space. This applies in particular to the particularly advantageous configuration of the invention in which the exhaust silencer consists structurally exclusively of a flap module comprising the flap arrangement and possibly an associated actuator, the inflow pipe and the outflow pipe, the primary and the secondary casing pipe, and the primary and the secondary helix insert. However, from an acoustic point of view, designs can also prove advantageous in which the respective casing pipe does not, or at most only in sections, form part of the outer wall bounding the functional space. The latter applies in particular to those configurations in which the primary casing pipe and/or the secondary casing pipe is perforated and surrounded at a radial distance by an associated cladding pipe, wherein the annular space existing between the perforated casing pipe and the cladding pipe is at least partially filled with an absorption material. Here, the respective cladding pipe can form part of the outer wall surrounding the functional space. For both conceptual configurations it applies that the respective casing pipe, in addition to the described fluidic function, can take on a serious static function as the decisive load-bearing component.

The primary and/or secondary helix insert described above, again in a particularly preferred configuration, is designed as a profiled helix pipe which rests along helical outer and inner contact lines against the outside of the associated casing pipe and against the inside of the inflow and outflow pipe, respectively. Contact lines in the above meaning are by no means lines in the mathematical sense alone, but rather and in particular also contact bands, i.e. helical contact surfaces. Such contact bands are created in particular when the spiral channels have an approximately trapezoidal cross-section, which is also preferably the case from a fluidic point of view.

The concept according to the invention can be applied very widely in that exhaust silencers constructed according to this concept can be excellently adapted to the installation situation existing in the respective vehicle. In particular, silencers according to the invention optimized for a particularly short overall length or for a particularly small cross-section can be implemented. In the configuration mentioned in first place, the two pairs of first and second spiral channels, on the one hand, and of third and fourth spiral channels, on the other, are arranged in a superimposed or overlapping manner in the sense that the one pair of spiral channel surrounds the other one radially on the outside; all four spiral channels surround either only the inflow pipe or only the outflow pipe in a helical manner, the four spiral channels preferably being distributed in pairs over two mutually concentric annular spaces. In the configuration mentioned -9 -in second place, the two pairs of first and second spiral channels, on the one hand, and of third and fourth spiral channels, on the other hand, are, in contrast, offset relative to one another in the axial direction, i.e. arranged next to one another. The above-mentioned, preferably provided fifth dedicated flow deflection can be implemented in this case by designing the third spiral channel with a screwing direction opposite to that of the second spiral channel.

If the two pairs of first and second spiral channels, on the one hand, and third and fourth spiral channels, on the other hand, are offset from one another in the axial direction in the above-mentioned meaning, they are positioned, according to a very particularly preferred configuration of the invention, on different sides of the flap arrangement. In this case, the first and the second spiral channels each surround the inflow pipe, and the third and the fourth spiral channels each surround the outflow pipe in a helical manner, wherein a flow through the first spiral channel can pass in a direction opposite to the exhaust flow in the inflow pipe and a flow through the fourth spiral channel can pass in a direction opposite to the exhaust flow in the outflow pipe. This is very advantageous not only from the point of view of the particularly easy, modular, individual adaptability of the silencer to different requirements, but also in terms of fluidics and with regard to the statics relevant for durability and ease of producibility.

Likewise, from a structural point of view, it is particularly advantageous if the flow guide of the flap arrangement and the bypass bypassing the flap arrangement are implemented in a uniform flap housing. Details of this, for example the possible structural connection of the inflow pipe and outflow pipe to the flap housing, are described in more detail below. From a fluidic point of view, it is particularly advantageous if the flap housing has a flow-deflecting first recess delimiting the first passage and/or a flow-deflecting second recess delimiting the second passage.

The concept according to the invention facilitates individual adaptation of the respective exhaust silencer to the existing installation and operating situation (including adapting to the respective internal combustion engine). Especially, different configuration features (possibly combined with one another), in each case in a preferred refinement of the invention, can be used for this purpose. Thus, the first spiral channel can communicate with the interior of the inflow pipe via perforations which are provided in the inflow pipe and the cross-section of which is small with respect to the first passage, and/or the fourth spiral channel can communicate with the interior of the outflow pipe via perforations which are provided in the outflow pipe and the cross-section of which is small with respect to the second passage. Also, the second spiral channel can communicate with the interior of the outflow pipe via perforations which are provided in the inflow pipe and the cross-section of which is small with respect to the first passage, and/or the third spiral channel can communicate with the interior of the outflow pipe via perforations which are provided in the outflow pipe and the cross-section of which is small with respect to the second passage.

According to yet another preferred refinement of the invention, the first and the second spiral channels are separated from one another by a primary helix insert and run with the identical radius in the same primary annular space formed radially on the outside by a primary casing pipe and/or the third and fourth spiral channels are separated from one another by a secondary helix insert and run with the identical radius in the same secondary annular space formed radially on the outside by a secondary casing pipe. The individual configuration of the respective helix insert, which is particularly preferably designed as a profiled helix pipe that rests along helical outer and inner contact lines against the associated casing pipe and the inflow an outflow pipes, results again in excellent possibilities for individual adaptation of the respective exhaust silencer to the specific application. Especially, for this purpose, the respective helix insert can have an electrically heatable surface and/or a catalytically active surface coating and/or a porous, elastic or otherwise acoustically attenuating surface structure. Furthermore, it can be perforated so that the two spiral channels separated from each other by means of the respective helix insert communicate with each other via the respective perforation. Furthermore, the respective helix insert can be structured in a multilayer sandwich-like manner with an absorption layer arranged between two perforated dimensionally rigid outer layers. All the adaptations made possible here, in particular acoustically effective adaptations, do not affect the concept and construction in other respects.

While the present invention can also be advantageously implemented in connection with passive flap arrangements, its particular advantages come into effect in a particularly pronounced manner in connection with active flap arrangements. In this sense, an actuator by means of which the flap can be actively adjusted is preferably associated with the flap arrangement. Especially, the actuator can be designed for proportional flap adjustment, which enables differentiated influencing of the silencing characteristics.

In the following, the present invention is explained by means of several preferred exemplary embodiments illustrated in the drawing. In the figures: -12 -Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 5 Fig. 6 Fig. 7 Fig. 8 Fig. 9 shows a perspective view of an exhaust silencer according to a first exemplary embodiment of the invention, shows a vertical axial section through the exhaust silencer according to Fig. 1, shows a horizontal axial section through the exhaust silencer according to Figs. 1 and 2, shows a partial axial section of a first variation of the exhaust silencer according to Figures 1 to 3, shows a partial axial section of a second variation of the exhaust silencer according to Figures 1 to 3, shows a partial axial section of a third variation of the exhaust silencer according to Figures 1 to 3, shows a partial axial section of a fourth variation of the exhaust silencer according to Figures 1 to 3, shows a (schematic) first axial section of an exhaust silencer according to a second exemplary embodiment of the invention, and shows the exhaust silencer according to Fig. 8 in a (schematic) second axial section normal to Fig. 7.

The exhaust silencer according to Figures 1 to 3 consists structurally of a flap module 1, two casing pipes in the form of a primary casing pipe 2 (on the inflow side) and a -13 -secondary casing pipe 3 (on the outflow side) sealingly attached to both sides of the flap module, an inflow pipe 4 and an outflow pipe 5 as well as a primary helix insert 6 and a secondary helix insert 7. The inflow pipe 4 and the outflow pipe 5 are aligned with each other; they lie on the longitudinal axis L of the exhaust silencer. The primary casing pipe 2 comprises, in addition to the cylindrical pipe section 8, an end piece 9 connected to the latter, which closes off the end of the primary annular space 10 defined and delimited by the inflow pipe 4 and the pipe section 8 surrounding it. The same applies to the configuration on the outflow side of the exhaust silencer, especially the secondary annular space 11 and the associated secondary helical insert 7.

The flap module 1 comprises a flap housing 13 with an aperture 15 extending therethrough and forming a flow guide 14, an adjustable flap 16, i.e. a flap pivotable about a pivot axis A, used to change the free flow cross-section of the flow guide 14, and an actuator 17 used to change the pivot position of the flap 16.

The primary helix insert 6 is designed as a profiled helix pipe 18, which rests along a helical outer contact line 19 against the cylindrical pipe section 8 of the primary casing pipe 2 and along a helical inner contact line 20 against the inflow pipe 4. In this manner, it separates two spiral channels, namely a first spiral channel 21 and a second spiral channel 22, from each other. While the primary helix insert 6, i.e. the profiled helix pipe 18 forming it, rests at its one end with the end face against the flap housing 13, at the opposite end, it keeps a distance from the end piece 9. In this manner, a first deflection zone 23 is formed which fluidically connects the first spiral channel 21 and the second spiral channel 22. For fluidically connecting the first spiral channel 21 to the inflow pipe 4, a first passage 24 is provided which is -14 -delimited by an inclined partial cut end 25 of the inflow pipe 4 as well as by a flow-deflecting first recess 26 formed in the flap housing 13. The above applies analogously to the secondary helix insert 7 separating a third spiral channel 27 and a fourth spiral channel 28 from one another, the outflow pipe 5 and the side of the flap housing 13 associated with the latter.

For fluidically connecting the third spiral channel 27 to the second spiral channel 22, the flap housing 13 has a passage opening 30 which, as a bypass 29 to the flow guide 14, forms a transition zone O. In the exhaust silencer according to Figures 1 to 3, the outer wall 31, which delimits the functional space F containing flow-conducting built-in components E, is thus formed primarily by the two casing pipes 2, 3. The inflow pipe 4 (also) forms the exhaust inlet AE of the exhaust silencer and the outflow pipe (also) forms the exhaust outlet AA. And the bypass arrangement provided for the flow guide 14 of the flap arrangement 32 defined by the latter and the flap cooperating therewith, comprises: a first spiral channel 21 which helically surrounds the inflow pipe 4 and which is fluidically connected to the inflow pipe 4 via a first passage 24 arranged adjacent to the flap arrangement 32 and -as far as the axial component of the spiral flow is concerned -through which a flow can pass in the opposite direction to the exhaust flow S in the inflow pipe 4, a second spiral channel 22 which is fluidically connected to the first spiral channel 21 in the region of a first deflection zone 23 and surrounds the inflow pipe 4 helically and through -15 -which a flow can pass in the same direction as the exhaust flow S in the inflow pipe 4, a bypass 29 fluidically connected to the second spiral channel 22 and bypassing the flap arrangement 32, a third spiral channel 27 which is fluidically connected to the bypass 29 and surrounds the outflow pipe 5 helically and through which a flow can pass in the same direction as the exhaust flow T in the outflow pipe 5, and a fourth spiral channel 28 which is fluidically connected to the third spiral channel 27 in the region of a second deflection zone 34 and surrounds the outflow pipe 5 helically and through which a flow can pass in the opposite direction to the exhaust flow T in the outflow pipe 5, and which is fluidically connected to the outflow pipe 5 via a second passage 35 arranged adjacent to the flap arrangement 32.

In the embodiment illustrated, the cross-sectional area of the primary annular space IC determined perpendicular to the longitudinal axis L in each case corresponds to about 2.8 times the cross-sectional area of the inflow pipe 4. The pitch of the first spiral channel 21 and the second spiral channel 22 is about 2.3 times the inner diameter of the inflow pipe 4. And the first spiral channel 21 and the second spiral channel 22 each extend over a screwing angle of about 450°. The cross-sectional area of the first spiral channel 21 and the second spiral channel 22 determined perpendicular to the respective spiral guide line, i.e., the cross-sectional area of the first and second spiral channels 21 and 22, respectively, in a plane oriented perpendicular to the direction of the screwing line at the -16 -respective center of the area, is about 0.73 times the cross-sectional area of the inflow pipe 4. The same applies to the situation on the outflow side.

Fig. 4 illustrates a variation of the exhaust silencer according to Figures 1 to 3 in that the first spiral channel 21 communicates with the interior of the inflow pipe 4 via perforations 36 which are provided in the inflow pipe 4 and the cross-section of which is small with respect to the first passage 24.

Fig. 5 illustrates a variation of the exhaust silencer according to Figs. 1 to 3 in that the first spiral channel 21 communicates with the second spiral channel 22 via perforations 37 which are provided in the helix pipe 18 forming the primary helix insert 6.

Fig. 6 illustrates a variation of the exhaust silencer according to Figures 1 to 3 in that the primary casing pipe 2, namely its cylindrical pipe section 8, is designed to be perforated and is surrounded at a radial distance by an associated cladding pipe 38, wherein the annular space 39 existing between the perforated casing pipe 2 and the cladding pipe 38 is filled with an absorption material 40.

Fig. 7 illustrates a variation of the exhaust silencer according to Figures 1 to 3 in that the primary helix insert 6 is structured in a multilayer sandwich-like manner with an absorption layer arranged between two perforated dimensionally rigid outer layers 41 42.

The exemplary embodiment for an exhaust silencer according to the present invention illustrated in Figures 8 and 9 is largely self-explanatory to a person skilled in the art from the above explanations of the first exemplary embodiment in Figures 1 to 3. Identical reference signs are assigned to identical components. It can be seen that here -17 -the primary annular space 10, which is subdivided by the primary helical insert 6 into the first helical channel 21 and the second helical channel 22, and the secondary annular space 11, which is subdivided by the secondary helical insert 7 into the third helical channel 27 and the fourth helical channel 28, are radially nested with one another. They are separated from each other by a separation pipe 43. The primary annular space 10 concentrically surrounds the secondary annular space 11, which in turn surrounds the outflow pipe 5. The fluidic connection of the third spiral channel 27 to the second spiral channel 22 is done via a deflector depression 44 in the flap housing 13. The exhaust flow enters the first spiral channel 21 via an aperture 45 in the flap housing 13 downstream of the passage 24.

It is obvious that the variations and modifications shown in Figures 4 to 7 -in some cases adapted accordingly -can also be applied with comparable advantages to the exemplary embodiment according to Figures 8 and 9.

Claims

-18 -CLAIMS1. An exhaust silencer for a combustion engine, comprising a functional space (F) which is delimited by an outer wall (31) and has an exhaust inlet (AE), an exhaust outlet (AA) and flow-conducting built-in components (E), wherein the flow-conducting built-in components (E) comprise at least one flap arrangement (32) with a flow guide (14) which is connected to an inflow pipe (4) communicating with the exhaust inlet (AE) and to an outflow pipe (5) communicating with the exhaust outlet (AA), and an adjustable flap (16) associated with the flow guide (14) and serving to vary the free flow cross-section of the flow guide (14), and wherein, furthermore, a flow can pass through a bypass arrangement existing in fluidic parallel connection to the flow guide (14) of the flap arrangement (32) in dependence on the momentarily free flow cross-section of the flow guide (14), characterized in that the bypass arrangement comprises a flow path with a helical first spiral channel (21) which is fluidically connected to the inflow pipe (4) via a first passage (24) arranged adjacent to the flap arrangement (32), a helical second spiral channel (22), which is fluidically connected to the first spiral channel (21) in the region of a first deflection zone (23) and through which a flow can pass in the opposite direction to the exhaust flow in the first spiral channel (21), a helical third spiral channel (27) which is fluidically connected to the second spiral -19 -channel (22) in the region of a transition zone (U), and a helical fourth spiral channel (28) which is fluidically connected to the third spiral channel (27) in the region of a second deflection zone (34) and through which a flow can pass in the opposite direction to the exhaust flow in the third spiral channel (27) and which is fluidically connected to the outflow pipe (5) via a second passage (35) arranged adjacent to the flap arrangement (32).
2. The exhaust silencer according to claim 1, characterized in that the first and the second spiral channels (21, 22) each helically surround the inflow pipe (4) and the third and the fourth spiral channels (27, 28) each helically surround the outflow pipe (5), wherein a flow can pass through the first spiral channel (21) in opposite direction to the exhaust flow (S) in the inflow pipe (4) and a flow can pass through the fourth spiral channel (28) in opposite direction to the exhaust flow (T) in the outflow pipe (5), and the transition zone (0) comprises a bypass (29) bypassing the flap arrangement (32).
3. The exhaust silencer according to claim 2, characterized in that the third spiral channel (27) is designed with a screwing direction opposite to that of the second spiral channel (22).
4. The exhaust silencer according to claim 2 or 3, characterized in that the flow guide (14) of the flap arrangement (32) and the bypass (29) are implemented in a uniform flap housing (13).
-20 - 5. The exhaust silencer according to claim 4, characterized in that the flap housing (13) has a flow-deflecting first recess (26) delimiting the first passage (24) and/or a flow-deflecting second recess delimiting the second passage (35).
6. The exhaust silencer according to claim 1, characterized in that all four spiral channels (21, 22, 27, 28) surround either only the inflow pipe (4) or only the outflow pipe (5) in a helical manner, wherein the four spiral channels (21, 22, 27, 28) are preferably distributed in pairs over two mutually concentric annular spaces (10, 11).
7. The exhaust silencer according to any one of claims 1 to 6, characterized in that the first spiral channel (21) communicates with the interior of the inflow pipe (4) via perforations (36) which are provided in the inflow pipe (4) and the cross-section of which is preferably small with respect to the first passage (24), and/or in that the fourth spiral channel (28) communicates with the interior of the outflow pipe (5) via perforations which are provided in the outflow pipe (5) and the cross-section of which is preferably small with respect to the second passage (35).
8. The exhaust silencer according to any one of claims 1 to 7, characterized in that the second spiral channel (22) communicates with the interior of the inflow pipe (4) via perforations (36) which are provided in the inflow pipe (4) and the cross section of which is preferably small with respect to the first passage (24), and/or in that the third spiral channel (27) communicates with the interior of the outflow pipe (5) via perforations which are provided in the outflow pipe (5) and the cross section of which is preferably small with respect to the second passage (35).
-21 - 9. The exhaust silencer according to any one of claims 1 to 8, characterized in that the first and the second spiral channels (21, 22) run with different radii in two different primary annular spaces (10) concentrically surrounding the inflow pipe (4), and/or in that the third and the fourth spiral channels (27, 28) run with different radii in two different secondary annular spaces (11) concentrically surrounding the outflow pipe (5).
10. The exhaust silencer according to any one of claims 1 to 8, characterized in that the first and the second spiral channels (21, 22) are separated from each other by a primary helix insert (6) and run with the identical radius in the same primary annular space (10) formed or delimited radially outside by a primary casing pipe (2).
11. The exhaust silencer according to any one of claims 1 to 8, characterized in that the third and fourth spiral channels (27, 28) are separated from each other by a secondary helix insert (7) and run with the identical radius in the same secondary annular space (11) formed or delimited radially outside by a secondary casing pipe (3).
12. The exhaust silencer according to claim 10 or 11, characterized in that the wall of the primary helix insert (6) delimiting the first spiral channel (21) and the second spiral channel (22) from one another and/or in that the wall of the secondary helical insert (7) delimiting the third spiral channel (27) and the fourth spiral channel (28) from one another has a perforation (37) via which the two respective spiral channels (21, 22; 27, 28) communicate with one another.
-22 - 13 The exhaust silencer according to any one of claims 10 to 12, characterized in that the primary helix insert (6) and/or the secondary helix insert (7) are designed as a profiled helix pipe (18) which rests along helical outer and inner contact lines (19, 20) against the associated casing pipe (2; 3) and the inflow and outflow pipes (4; 5).
14. The exhaust silencer according to claim 13, characterized in that the at least one profiled helix pipe (18) rests with the end face against a flap housing (13) within the meaning of claim 4.
15. The exhaust silencer according to any one of claims 10 to 14, characterized in that the primary casing pipe (2) and/or the secondary casing pipe (3) forms part of the outer wall (31) delimiting the functional space (F).
16 The exhaust silencer according to claim 15, characterized in that structurally, the exhaust silencer consists exclusively of a flap module (1) comprising the flap arrangement (32) and an associated actuator (17), the inflow pipe (4) and the outflow pipe (5), the primary and the secondary casing pipes (2, 3) as well as the primary and the secondary helix inserts (6, 7).
17. The exhaust silencer according to any one of claims 10 to 14, characterized in that the primary casing pipe (2) and/or the secondary casing pipe (3) is designed to be perforated and is surrounded at a radial distance by an associated cladding pipe (38), wherein the annular space (39) existing between the perforated casing pipe (2, 3) and the cladding pipe (38) is at -23 -least partially filled with an absorption material (40).
18. The exhaust silencer according to any one of claims 10 to 17, characterized in that the first and/or the second helix insert (6, 7) has an electrically heatable surface.
19. The exhaust silencer according to any one of claims 10 to 18, characterized in that the first and/or the second helix insert (6, 7) has a catalytically active surface coating.
20. The exhaust silencer according to any one of claims 10 to 19, characterized in that the first and/or the second helix insert (6, 7) has a porous, elastic or otherwise acoustically attenuating surface structure.
21. The exhaust silencer according to any one of claims 10 to 20, characterized in that the first and/or the second helix insert (6, 7) is structured in a multilayer sandwich-like manner with an absorption layer (42) arranged between two perforated dimensionally rigid outer layers (41).
22. The exhaust silencer according to any one of claims 10 to 21, characterized in that the cross-sectional area of the primary annular space (10) is between 1.5 times and 4.5 times, particularly preferably between 2 times and 4 times, most preferably between 2.5 times and 3 times the cross-sectional of the inflow pipe (4), and/or in that the cross-sectional area of the secondary annular space (11) is between 1.5 times and 4.5 times, particularly preferably between 2 times and 4 times, most preferably between 2.5 times and 3.5 times the cross-sectional area of the outflow pipe (5).
-24 - 23. The exhaust silencer according to any one of claims 1 to 22, characterized in that the cross-sectional area of the first spiral channel (21) and of the second spiral channel (22) determined perpendicular to the respective spiral guide line is between 0.2 times and 2 times, preferably between 0.4 times and 1.5 times, particularly preferably between 0.6 times and 1.0 time the cross-sectional area of the inflow pipe (4) and/or in that the cross-sectional area of the third spiral channel (27) and of the fourth spiral channel (28) determined perpendicular to the respective spiral guide line is between 0.2 times and 2 times, preferably between 0.4 times and 1.5 times, particularly preferably between 0.6 times and 1.0 time the cross-sectional area of the outflow pipe (5).
24. The exhaust silencer according to any one of claims 1 to 23, characterized in that the pitch of the first and second spiral channels (21, 22) is between 1 time and 6 times, preferably between 1.5 times and 4 times, particularly preferably between 2 times and 3 times the inner diameter of the inflow pipe (4), and/or in that the pitch of the third and fourth spiral channels (27, 28) is between 1 time and 6 times, preferably between 1.5 times and 4 times, particularly preferably between 2 times and 3 times the inner diameter of the outflow pipe (5).
25. The exhaust silencer according to any one of claims 1 to 24, characterized in that the first and the second spiral channels (21, 22) and/or in that the third and the fourth spiral channels (27, 28) each extend over a screwing angle of between 180° and 720°, preferably between 225° and 630°, particularly preferably between 270° and 540°.
-25 - 26. The exhaust silencer according to any one of claims 1 to 25, characterized in that the first passage (24) is delimited by an oblique partial cut end (25) of the inflow pipe (4) and/or in that the second passage (35) is delimited by an oblique partial cut end of the outflow pipe (5).
27. The exhaust silencer according to any one of claims 1 to 26, characterized in that the flap arrangement (32) is assigned an actuator (17) by means of which the flap (16) can be actively adjusted.
28. The exhaust silencer according to claim 27, characterized in that the actuator (17) is designed for proportional flap adjustment.