EP2446128B1 - Tubular acoustic insulating element - Google Patents

Description

The invention relates to an exhaust system for an internal combustion engine for connection to a manifold. The exhaust system consists of at least one in the flow direction middle or immediately after the manifold provided first portion and a subsequent flow in the second portion, the two sections are connected to each other via a mechanical decoupling element, wherein in the flow direction before the first section or in the first section a single-walled and self-supporting element is integrated into the exhaust system, wherein the element has at least one inner nozzle and at least one radially outwardly offset to a central axis outer nozzle, and in each case one between the two nozzles arranged connecting the two nozzles in the direction the center axis is provided in the length compressed center part, which forms a U or S-blow in cross section. Wherein the element is formed as an acoustic insulating element and formed of sheet metal or metal casting and in a direction along the workpiece continuously or suddenly increasing wall thicknesses between 1 mm and 2.8 mm, in particular between 1.2 mm and 1.9 mm.

By decoupling the exhaust system is mechanically decoupled, so that a certain flexibility over the vehicle length is given. As a mechanical decoupling non-self-supporting, flexible connecting elements such as shaft pipes or flexible hoses between two sections of the exhaust system are used. The fact that the shaft tubes or flexible hoses are not self-supporting, they must be supported become. Due to their low rigidity and flexibility, they also have the inherent property of damping vibrations in certain frequency ranges by a certain amount. Such flexible acoustic damping elements are for example in the US 5,456,291 A and in the EP 1 431 538 B1 described.

For a mechanical articulated decoupling of two pipe or housing flanges of an exhaust system, which allows a relative bending of the exhaust system, also compressed connecting elements between two sections are used, which have a hinge-like flexibility. This in the DE 198 12 611 C2 or in the JP 199789173 A (Hei9-89173) described are formed as a compressed pipe section that forms an S-shaped spring in longitudinal section. These fasteners are stiff due to the reduced waveform compared to the shaft tubes, but self-supporting. To increase the flexibility they can according to the DE 198 12 611 C2 be longitudinally slotted.

It is known that by various modern construction measures for exhaust systems and internal combustion engines despite a mechanical decoupling increasingly vibrations in the audible range caused by resonances in different components. Flatter forms of silencers, the use of thin-walled, air gap-insulated bends and turbochargers in diesel engines as well as changes in the combustion process lead to additional vibrations in the structures and thus to additional structure-borne noise.

This type of structure-borne noise can be caused by damping elements in the exhaust system or by large impedance jumps be reduced in components of an exhaust system directly in the structure.

Impedance jumps are in accordance with the DE 10 2006 040 980 A1 achieved with a damping element having radial extensions of the cross section, which are placed in the manner of a pipe clamp on the pipe.

In the DE 20 2004 005 526 U1 For the reduction of structure-borne noise, a rigid flange connection is described, which dampens the transmission of vibrations by means of a system which is linear in the circumferential direction about the pipe or flange axis.

In the EP 1 319 826 A1 an exhaust pipe is described with end coupling elements which serve the mechanical decoupling of the exhaust pipe.

The invention has for its object to dampen resonant vibrations in the range above 600 Hz in an exhaust system by more than 15 dB and at the same time form the exhaust system sufficiently rigid and self-supporting and permanently gas-tight.

The object is achieved in that the element is formed as an acoustic insulating element and is formed from sheet metal or metal casting and in one direction along the workpiece continuous or increasing wall thickness suddenly increasing between 1 mm and 2.8 mm, in particular between 1.2 mm and 1, 9 mm.

The achieved by a decreasing wall thickness insulating effect has an advantageous effect especially in the frequency range above 2000 Hz to 6000 Hz. This is advantageous in that when calibrating the diameter of the outer nozzle from a smaller on a greater degree the wall thickness becomes thinner anyway. Thus, a cylindrical tube having a base diameter matching the inner neck on the exit side would be up-calibrated to the dimension of the diameter for the outer neck.

It has been found by acoustic measurements that the known flexible and self-supporting mechanical decoupling elements in the form of a compressed pipe section with an S-beat in the frequency range above 600 Hz, in particular between 3000 Hz and 6000 Hz have not expected acoustic insulation properties, the interactions in the further exhaust system and the formation of structure-borne noise in significant dimensions reduced. The geometric and structural measures taken with regard to a maximum possible insulation led to the realization that even if the S-shaped decoupling element is relatively stiff and self-supporting, very good insulation properties can be achieved.

For this purpose, it is advantageous to form the tubular acoustic insulation element in the direction of the central axis as short as possible and thus to achieve sufficient bending stiffness in order to be used as a self-supporting acoustic insulation element can. In the area in which the acoustic insulation element is integrated into the exhaust system, it does not have to fulfill the function of a mechanical decoupling and can be designed relatively rigid.

It can also be essential that the insertion depth is between 5 mm and 16 mm, maximum 30 mm.

According to the invention, the insulating property can be further improved if the acoustic insulating element is connected directly in front of or on the component which ultimately generates the resonances in the continuing components. The inner radius and the outer radius advantageously have a dimension of between 6 mm and 30 mm, but the two radii have a different dimension relative to each other.

It may be advantageous for this purpose, if the inner nozzle is arranged offset in the direction of the central axis to the outer nozzle and / or cover the two sockets to the extent of an insertion depth e between 5 mm and 30 mm. The length of the insertion depth e is the extent to which the outer neck projects beyond the inner neck in the direction of the central axis. At this length, both the pipe part provided between the inner radius and the outer radius and the two radii themselves must be included in the dimension of the insertion depth e. The shorter the insertion depth e, the larger the acoustic insulation achieved with the element.

Further, it is advantageous that the basic diameter of the inner neck is at least 20% to a maximum of 40% smaller than the diameter of the outer neck. The insulation can be significantly influenced by the two end geometries of the two nozzles, since the vibration behavior in the transition from a small to a large nozzle deviates significantly from the vibration behavior that would be achieved if the inner nozzle would have the same measure as the inlet nozzle the outer nozzle as outlet nozzle. With respect to the insulating properties, it can be further advantageous if [4] a middle part connecting the two tubular connecting pieces has at least one outer radius adjoining the outer connecting piece and an inner radius adjoining the inner connecting piece and a tube part connecting the two radii, wherein the tube wall of the Pipe part is arranged in parallel or at an angle a between 2.5 ° and 15 ° to the central axis. This further possibility of influencing the insulating effect also has the advantage that the size of the two radii can be varied with existing connection geometry for the inner or the outer nozzle, that is, with very small radii of this pipe part includes an increasingly larger angle a to the central axis , Another advantage is that the connection geometry can be increased or decreased by varying the angle a for both the inner nozzle and the outer nozzle.

In addition, it can be advantageously provided if the acoustic insulation element in the flow direction S after the inner nozzle has a reduced diameter compared to the base diameter. By this measure, a kind of taper is formed in the transition from the inner nozzle to the central part, are influenced by the particular existing vibrations in the exhaust pipe with respect to the insulation.

Of particular importance may be for the present invention, when the acoustic insulation element is formed from a calibrated pipe section with an input side base diameter between 45 mm and 85 mm and an output side diameter between 55 mm and 115 mm and an absolute in the direction of the central axis length between 230 mm and 420 mm. The ratio of basic diameter to diameter significantly influences the insulation properties of the element.

In connection with the design and arrangement according to the invention, it may be advantageous if the acoustic insulating element is integrated in an end wall of a sheet metal housing for a filter or a converter or a silencer, wherein at least a part of the end wall in the radial direction to the central axis at the inner nozzle and / or connects to the outer neck. As a result, the integration of the Dämmelements is made possible in a present in the exhaust systems component to which an exhaust pipe would be connected anyway. The integration in an end wall also has the advantage that the overall length and thus the rigidity of the element can be increased, which has a significant effect on the insulation property.

It can also be advantageous if the acoustic insulating element is arranged at an outlet of a housing for a turbocharger. Since turbochargers contribute a relatively large contribution to the resulting in the exhaust system structure-borne noise in the range between 600 Hz and 6 kHz, positioning of such a Dämmelements immediately after the turbocharger is of great importance, also can be arranged by such an arrangement in the oversized nozzle easier to integrate larger diameter in the geometry of an exhaust system, because this outer nozzle connects directly to the housing and a possibly necessary reduction of the diameter is not necessary again to the extent of the provided for the other exhaust pipes diameter of the inner nozzle.

In addition, the use of an acoustic Dämmelements for an exhaust system for acoustic insulation of an exhaust system in the frequency range between 600 Hz and 6 kHz be advantageous if the acoustic insulation element has at least one inner nozzle and at least one radially outwardly offset to a central axis outer nozzle, in each case one arranged between the two stubs, connecting the two stubs compressed middle part is provided, which forms a U- or S-blow in cross-section and is formed from single sheet metal or metal casting and in a direction along the workpiece continuously or suddenly increasing wall thicknesses between 1 mm and 2.8 mm, in particular between 1.2 mm and 1.9 mm.

Figur 1

eine an einen Motor angeschlossene Abgasanlage;

Figur 2

einen Querschnitt eines dämmenden Elements, das zwischen zwei Bauteile einer Abgasanlage integriert ist;

Figur 3

einen oberen Teil eines Querschnitts eines Dämmelements mit einem gegenüber dem Grunddurchmesser verkleinerten Innendurchmesser;

Figur 4

einen Querschnitt eines dämmenden Elements mit einem gegenüber der Mittelachse angestellten Rohrteil;

Figur 5

die Integration eines Dämmelements in eine Stirnseite eines Gehäuses;

Figur 6

eine Bauweise nach Figur 5, bei der das Dämmelement in radialer Richtung mittig zur Stirnseite angeordnet ist;

Figur 7

eine Anordnung nach Figur 6, bei der das Dämmelement einem U-Schlag aufweist;

Figur 8

die Integration eines Dämmelements in eine kegelförmige Stirnseite eines Blechgehäuses.

Further advantages and details of the invention are explained in the patent claims and in the description and illustrated in the figures. It shows:

FIG. 1

an exhaust system connected to an engine;

FIG. 2

a cross-section of an insulating element which is integrated between two components of an exhaust system;

FIG. 3

an upper part of a cross section of a Dämmelements with an opposite the base diameter reduced inner diameter;

FIG. 4

a cross-section of a damping element with a relative to the central axis employed pipe part;

FIG. 5

the integration of a Dämmelements in a front side of a housing;

FIG. 6

a construction after FIG. 5 in which the insulating element is arranged in the radial direction centrally to the end face;

FIG. 7

an arrangement after FIG. 6 in which the insulating element has a U-stroke;

FIG. 8

the integration of a Dämmelements into a conical face of a sheet metal housing.

In FIG. 1 is an exhaust system 4 consisting of a first portion 41 and a second portion 42 shown. The first portion 41 is formed of a converter 45 and on both sides of the converter 45 respectively connected exhaust pipes 47. The second section 42 consists of a particulate filter 44 and a muffler 46, wherein the particulate filter 44 and the muffler 46 are connected to each other via an exhaust pipe 47. Upstream of the particulate filter 44, an exhaust pipe 47 is also provided, to which a mechanical decoupling element 40 connects, via which the two sections 41, 42 are interconnected. The mechanical decoupling element 40 serves essentially to ensure a certain freedom of movement of the exhaust system 4 over its entire length.

The entire exhaust system 4 is connected via an acoustic insulating element 1 to an outlet opening of a turbocharger 5, which further connects the exhaust system 4 via the manifold 3 with the engine 2. The vibrations introduced via the exhaust gas flow and the turbocharger 5 into the exhaust system 4 are significantly attenuated via the acoustic insulating element 1 in the range between 600 Hz and 6 kHz, so that the body radiation of the converter 45, of the particulate filter 44 and of the silencer 46 is reduced. At the same time, the vibrations still present in the first part 41 of the exhaust system 4 are also influenced and partially damped by the mechanical decoupling element 40, so that the combination of the acoustic insulation with the insulating element 1 and the vibration damping with the mechanical decoupling element 40 reduces the structure-borne noise in the second part 42 causes the exhaust system 4.

In FIG. 2 is a schematic cross section of an acoustic Dämmelements 1 shown with an S-beat 120. The acoustic insulating element 1 has an inner nozzle 10 and a radially outer to the central axis 13 outer nozzle 15. The outer nozzle 15 is in the axial direction to the central axis 13 via the inner nozzle 10 via. The connection of the outer nozzle 15 with the inner nozzle 10 forms a central part 12 with an S-beat 120 in cross section. The middle part 12 is formed by the outer radius 152 adjoining the outer connecting piece 15 and the inner radius 102 adjoining the inner connecting piece 10 and a tubular part 14 connecting the two radii 102, 152.

The projection of the outer nozzle 15 via the inner nozzle 10 is referred to as insertion depth e, which is formed in the sum of the dimension of the tube part 14 and the two radii 102, 152. The length L of Dämmelements 1 in the direction of the central axis 13 is measured from the inlet opening on the inner nozzle 10 to the outlet opening at the outer nozzle 15th

As in FIG. 2 shown, connects to the inner nozzle 10 in the flow direction S the insulating element 1 preceded by an exhaust pipe 47 at. In the flow direction S after the insulating element 1 is a schematically illustrated exhaust element 48, connected to the insulating element 1. In the FIGS. 5 to 8 Examples of such exhaust elements 48 are represented by sheet metal housing 43.

1. a) 350 Hz eine mittlere axiale Durchgangsdämmung von mindestens -18 dB und
2. b) 600 Hz eine mittlere axiale Durchgangsdämmung von mindestens 0 dB und
3. c) 1000 Hz eine mittlere axiale Durchgangsdämmung von mindestens 8 dB und
4. d) 3000 Hz eine mittlere axiale Durchgangsdämmung von mindestens 20 dB beträgt.

The S-beat 120 can in various embodiments, not shown, an input-side base diameter 101 between 45 mm and 85 mm and an output-side diameter 151 between 55 mm and 115 mm and an absolute length L between 230 mm and 420 mm in the direction of the central axis 13, wherein the ratio of the diameters 101, 151 and the length L can be chosen such that the natural frequency is at an average input frequency of

1. a) 350 Hz average axial transmission loss of at least -18 dB and
2. b) 600 Hz has a mean axial transmission loss of at least 0 dB and
3. c) 1000 Hz, a mean axial transmission loss of at least 8 dB and
4. d) 3000 Hz has a mean axial transmission loss of at least 20 dB.

With these parameters of the geometry, the natural frequency can be shifted in the range of 400 Hz to 700 Hz compared to a cylindrical exhaust pipe, with a positive insulation from 600 Hz or 900 HZ is achievable. Furthermore, a maximum insulation of 30 dB between 600 Hz 6 kHz can be realized.

FIG. 3 shows a particular embodiment of the S-beat 120, in which the pipe section 14 provided between the two radii 102, 152 is employed with respect to the central axis 13 by an angle a. It can be seen that the tube part 14 is thus not arranged parallel to the central axis 13, as for example in FIG FIG. 3 is shown. By varying the angle a, both the base diameter 101 of the inner nozzle 10 and the diameter 151 of the outer nozzle 15 to each other can be varied. In particular, when the acoustic insulating element 1 is manufactured and calibrated from a cylindrical tube which has a tube diameter substantially equal to the basic diameter 101 corresponds to the inner nozzle 10, the outer nozzle 15 is calibrated by a certain amount. According to the required geometrical dimensions and with regard to the relevant for the outer nozzle 15 wall thickness, in particular when the inner and the outer radius 102, 152 should have a fixed size, by the variation of the angle a of the diameter 151 of the outer nozzle 15th be varied. Also in this embodiment, the insertion depth e by the dimensions of the two radii 102, 152 and the length L of the pipe part a in the direction of the central axis 13 prevail.

In FIG. 4 is one opposite FIG. 3 modified embodiment shown in which in the region of the inner radius 102 of the inner diameter 103 is reduced relative to the base diameter 101 of the inner nozzle 10. In the flow direction S, a compression of the exhaust gas flow is thus achieved and at the same time influence on the running in the inner nozzle 10 sound waves.

FIG. 5 shows a preferred embodiment in which the acoustic insulation element 1 is integrated into an end wall 430 of a sheet metal housing 43 of an exhaust system 4. In particular, in winding mufflers, the end face 430 is inserted in the direction of the central axis 13 in the sheet metal housing 43, so that a mounting of the insulating element 1 in the end wall 430 before winding the housing is possible. For this purpose, the insulating element 1 is welded to the outer nozzle 15 in a corresponding opening of the end wall 430. The opposite of the inner nozzle 10 in diameter 151 substantially larger outer nozzle 15 forms, so to speak, the output side for the flowing in the flow direction S exhaust, so that the exhaust gas or the exhaust stream after the insulating element 1 on in the sheet metal housing 43 propagates in the radial direction. This also has the advantage that by reducing the diameter 151 of the outer nozzle 15, if necessary, with a continuation within the exhaust pipe, which has approximately the same diameter as the inner nozzle 10, a taper can be avoided.

In FIG. 6 is a similar embodiment as in FIG. 5 with regard to the positioning in an end wall 430 of a sheet-metal housing 43. In this case, however, the S-shaped insulating element 1 is arranged in the radial direction to the central axis 13 approximately in the middle of the end wall 430, so starting from the mounted in the end wall 430 exhaust pipe 47 initially a first part of the end wall 430 in the radial direction a connection to Dämmelement 1 forms and to the insulating element 1 in the radial direction then a second part of the end wall 430, the connection and the connection to the circumferentially arranged sheet metal housing 43 represents. In this embodiment, the inner nozzle 10 and the outer nozzle 15 is formed extremely short and the adjacent components are not arranged as in the previous embodiments in the axial direction to the central axis 13 adjacent to the insulating element 1 but in the radial direction.

In FIG. 7 is one too FIG. 6 similar embodiment shown, in which the insulating element 1 does not have an S-shaped cross-section but a U-shaped cross section 120. The U-shaped insulating element 1 has only a radius, which is referred to as inner radius 102 and can be used only in the areas due to the geometric conditions in which connect the other components in the radial direction to the central axis 13 to the insulating element 1.

In FIG. 8 an embodiment is shown, in which the insulating element 1 forms a connection between an exhaust pipe 47 and a sheet metal housing 43, wherein the sheet metal housing 43 has a conical end face. Again, the larger diameter 151 of the outer nozzle 15 with respect to the inner nozzle 10 is advantageously carried out via the connection to the sheet metal housing 43, so that a tapering of the diameter 152 of the outer nozzle 15 to a smaller extent is not necessary.

Claims (9)

1. An exhaust system (4) formed of a plurality of components for an internal combustion engine (2) for connecting to a manifold (3), comprising at least one first section (41) forming a start in the flow direction S and one second section (42) following said first section in the flow direction S, wherein the two sections (41, 42) are connected to one another via a mechanical decoupling element (40), wherein a single-walled and self-supporting element (1) is integrated in the exhaust system (4) upstream of the first section in the flow direction S or in the first section (41), wherein the element (1) has at least one inner connecting piece (10) and at least one outer connecting piece (15) which is offset outwards in the radial direction relative to a central axis (13), and a middle part (12) is provided which is arranged between the two connecting pieces (10, 15), connects the two connecting pieces (10, 15) and is compressed in length (L) in the direction of the central axis (13), said middle part forming in cross-section a U-shaped or S-shaped stop (120), characterized in that the element is configured as an acoustic insulating element (1) and is formed of sheet metal or cast metal and has wall thicknesses of between 1 mm and 2.8 mm, in particular between 1.2 mm and 1.9 mm, said wall thicknesses increasing continuously or in jumps in a direction along the workpiece.
2. The exhaust system (4) according to claim 1, characterized in that, on the insulating element (1), the inner connecting piece (10) is arranged offset in relation to the outer connecting piece (15) in the direction of the central axis and/or the two connecting pieces (10, 15) overlap by the size of a push-in depth (e) of between 5 mm and 30 mm.
3. The exhaust system (4) according to claim 1 or 2, characterized in that, on the insulating element (1), the basic diameter (101) of the inner connecting piece (10) is at least 20% to at most 40% smaller than the diameter (151) of the outer connecting piece (15).
4. The exhaust system (4) according to any of the preceding claims, characterized in that, on the insulating element (1), the middle part (12) connecting the two tubular connecting pieces (10, 15) has at least one outer radius (152) connecting to the outer connecting piece (15) and one inner radius (102) connecting to the inner connecting piece (10), as well as a pipe part (14) connecting the two radii (102, 152), wherein the pipe wall of the pipe part (14) is arranged parallel to or at an angle a of between 2.5° and 15° to the central axis (13).
5. The exhaust system (4) according to any of the preceding claims, characterized in that the acoustic insulating element (1) has, downstream of the inner connecting piece (10) in the flow direction S, an internal diameter (103) which is reduced in comparison to the basic diameter (101).
6. The exhaust system (4) according to any of the preceding claims, characterized in that the insulating element (1) is formed of a calibrated pipe section having a basic diameter (101) of between 45 mm and 85 mm on the inlet side and a diameter (151) of between 55 mm and 115 mm on the outlet side, as well as an absolute length (1) of between 230 mm and 420 mm in the direction of the central axis (13).
7. The exhaust system (4) according to any of the preceding claims, characterized in that the acoustic insulating element (1) is integrated in an end wall (430) of a sheet metal housing (43) for a particle filter (44) or a converter (45) or a silencer (46), wherein at least a portion connects the end wall (430) to the inner connecting piece (10) and/or to the outer connecting piece (15) in the radial direction relative to the central axis (13).
8. The exhaust system (4) according to any of the preceding claims 1 to 7, characterized in that the acoustic insulating element (1) is arranged at an outlet of a housing for a turbocharger (5).
9. The use of an acoustic insulating element (1) for an exhaust system (4) for acoustically insulating an exhaust system (4) in the frequency range between 600 Hz and 6 kHz, wherein the acoustic insulating element (1) has at least one inner connecting piece (10) and at least one outer connecting piece (15) which is offset outwards in the radial direction relative to a central axis (13), a middle part (12) is provided which is arranged between the two connecting pieces (10, 15), connects the two connecting pieces (10, 15) and is compressed in length (L) in the direction of the central axis (13), said middle part forming in cross-section a U-shaped or S-shaped stop (120), and the acoustic insulating element (1) is formed of sheet metal or cast metal in a single-walled manner and has wall thicknesses of between 1 mm and 2.8 mm, in particular between 1.2 mm and 1.9 mm, said wall thicknesses increasing continuously or in jumps in a direction along the workpiece.

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