Patent Application
20230003162
This application claims priority of German patent application no. 10 2021 116 802.3, filed Jun. 30, 2021, the entire content of which is incorporated herein by reference.
The present disclosure relates to a muffler for an exhaust system of an internal combustion engine, for example in a motor vehicle.
Such a muffler, known for example from US 2008/0196969, comprises a muffler housing with a circumferential wall and a plurality of base walls which are surrounded by the circumferential wall and are carried on the latter. Base walls of this type form respective end walls, which close off the interior of the muffler housing in the direction of a housing longitudinal axis from the outside, in the two axial end regions of the circumferential wall. Base walls of this type form respective intermediate walls, which separate chambers formed inside the muffler housing from one another, in that region of the muffler housing which is situated between the two end walls. Such chambers can be interconnected via openings provided in a respective intermediate wall but can also form a resonator chamber for a Helmholtz resonator.
In order to be able to pass an exhaust pipe, which can also provide a resonator neck for such Helmholtz resonance, through such a base wall, it is known, by forming a passage, to form an opening edge region which surrounds a base wall opening and extends from an essentially plane region of a respective base wall in the direction of an opening center axis of a respective base wall opening. This opening edge region has an essentially cylindrical structure and receives an exhaust pipe. Such base wall openings which are surrounded by a respective opening edge region are oversized with regard to their external dimensions, that is, for example the external diameter of an exhaust pipe constructed with an essentially circular cross-section, such that an exhaust pipe can be received in such a base wall opening with a small amount of play and can thus be brought into an installed position provided for it. In this position, a respective exhaust pipe is then connected, generally by welding, to the base wall through which it passes to make a firm bond.
An object of the present disclosure is to provide a muffler for an exhaust system of an internal combustion engine, and a method for producing such a muffler, by which a connection can be effected between a base wall and an exhaust pipe passing through the latter which prevents the generation of noise.
According to an aspect of the present disclosure, this object is achieved by a muffler for an exhaust system of an internal combustion engine, comprising a muffler housing with a circumferential wall which extends longitudinally in the direction of a housing longitudinal axis and at least one base wall which is surrounded by the circumferential wall or/and retained on the circumferential wall and delimits a chamber in the muffler housing, wherein at least one base wall opening, which is surrounded by an opening edge region which is bent at an essentially plane base wall region of the base wall essentially in the direction of the housing longitudinal axis, and receives an exhaust pipe with a press fit, is provided in at least one base wall.
In the case of the muffler according to the disclosure, at least one exhaust pipe is retained in an assigned base wall opening by a press fit, as a result of which, on the one hand, a stable bond is achieved and, on the other hand, the creation of relative movements between the base wall and the exhaust pipe which passes through it, which can cause impact noises or rattling noises, is prevented because of constantly present bearing contact which is under pressure or pretension. Further measures for providing a firm bond are in principle not required, wherein, however, a material connection, for example a connection by welding, can be provided in addition to retention by a press fit.
In particular when it is intended to obtain a gastight closure in the region of the connection of a base wall to an exhaust pipe, for example to provide a Helmholtz resonator, it is advantageous if the opening edge region is configured so that it runs completely circumferentially about an opening center axis of the base wall opening.
In an alternative embodiment, the opening edge region can be configured so that is interrupted circumferentially about an opening center axis of the base wall opening. For example, it can be implemented by the opening edge region comprising a plurality of opening edge region segments arranged spaced apart from another circumferentially about an opening center axis of the base wall opening.
In an embodiment which can be implemented cost-effectively and is at the same time resistant to high temperatures and aggressive constituents of exhaust gas of an internal combustion engine, the at least one base wall can be configured as a deformed sheet-metal part. In particular when it is intended that the opening edge region is closed circumferentially, in order for example also to obtain an essentially gastight closure, it is advantageous if at least one base wall has a wall thickness of no more than 1 mm, preferably no more than 0.6 mm. In this case, the base wall can also be sufficiently deformable in the region of its elastic deformability, also in the region of the closed opening edge region in order to generate the press fit when pushing or pressing the exhaust pipe into the base wall opening, to be able to receive an exhaust pipe and to be able to generate a sufficiently high contact pressure against its outer circumferential surface.
The opening edge region can have a first edge section adjoining the essentially plane base wall region in a first bending region and a second edge section adjoining the first edge section in a second bending region, wherein a radial spacing of the first edge section from an opening center axis of the base wall opening decreases preferably essentially constantly in the direction from the first bending region to the second bending region. The region of the minimum spacing of the opening edge region from the opening center axis can then be provided in the region of the second bending region.
A radial spacing of the second edge section from the opening center axis can be essentially constant in a direction away from the second bending region such that an essentially cylindrical region is formed in which a flat bearing contact is formed between the opening edge region and the exhaust pipe. A material connection, that is, for example a welded connection, between the base wall and the exhaust pipe, can, for example, be produced at am end side of this cylindrical section.
In an embodiment which assists in particular the easy pressing of the exhaust pipe into a base wall opening which receives it and which prevents the occurrence of jamming when an exhaust pipe is pushed into a base wall opening, a radial spacing of the second edge section from the opening center axis can increase preferably essentially constantly in the direction away from the second bending region.
It can furthermore be provided that the opening edge region runs in bent form from a first axial end region, adjoining the essentially plane region of the base wall, of the opening edge region to an axial region of the opening edge region with a minimum spacing from an opening center axis of the base wall opening.
Furthermore, if the opening edge region here runs in bent form from the region of the opening edge region with a minimum spacing from the opening center axis of the base wall opening to a second axial end region, remote from the essentially plane region of the base wall, of the opening edge region, the whole opening edge region can be provided, for example, as a deforming region, with an approximately constant radius of curvature in the axial direction, of the base wall.
The at least one base wall can be an intermediate wall separating two chambers in the muffler housing from each other. Alternatively, the at least one base wall can be an end wall arranged at an axial end region of the circumferential wall. It should be pointed out that of course one or more intermediate walls and one or both end walls can be configured in a muffler as a base wall with the above described structure. It should furthermore be pointed out that it is also possible for a plurality of base wall openings, one or possibly several or all of which can have the above described structure for receiving a respective exhaust pipe with a press fit, to be formed in one or more such base walls.
According to a further aspect, the object stated at the beginning is achieved by a method for producing a muffler for an exhaust system of an internal combustion engine, in particular of a muffler constructed according to the disclosure, comprising the steps:
It should be pointed out that the dimensions which need to be provided so that they are specifically harmonized with each other need to be considered in those regions which interact with each other when the muffler is assembled.
This means that the exhaust pipe is oversized, in the region in which it traverses a base wall when the muffler is assembled, compared with the base wall opening formed to receive this exhaust pipe in the base wall, but in other longitudinal regions it can have, for example, a smaller dimension in cross-section, or possibly an even larger dimension in cross-section, than this base wall opening.
It should furthermore be pointed out that, in the case of a muffler constructed according to the disclosure or the method to be performed according to the disclosure, such a base wall opening and an exhaust pipe to be received therein are preferably in each case formed with a circular cross-section such that the internal dimension can be represented, for example, by the internal diameter and the external dimension can be represented, for example, by the external diameter.
In step a), the opening edge region can be provided so that it runs completely circumferentially about the opening center axis. Alternatively, it can be provided that, in step a), the opening edge region is provided so that it is interrupted in at least one circumferential region. The opening edge region can, for example, be configured here with a plurality of opening edge region segments arranged spaced apart from one another circumferentially about the opening center axis.
In step a), the opening edge region be provided, starting from the essentially plane region of the base wall, with a spacing from the opening center axis which decreases as far as an axial region of the opening edge region with a minimum spacing from the opening center axis.
Furthermore, in step a), the opening edge region can be provided with an essentially constant spacing from the opening center axis from the region of the opening edge region with a minimum spacing from the opening center axis as far as a free axial end region of the opening edge region. Alternatively, in step a), the opening edge region be provided with a spacing from the opening center axis which increases from the region of the opening edge region with a minimum spacing from the opening center axis as far as the free axial end region of the opening edge region.
In order, on the one hand, to enable the introduction of an exhaust pipe into a base wall opening and, on the other hand, to obtain a sufficiently firm press fit, it is proposed that a difference between the predetermined external dimension of the exhaust pipe and the predetermined internal dimension of the base wall opening provided to receive the exhaust pipe is in the range from 0.2 mm to 0.6 mm, preferably is approximately 0.4 mm. For this purpose, it can furthermore be provided that, in step a), the at least one base wall is provided as a deformed sheet-metal part or/and with a wall thickness of no more than 1 mm, preferably no more than 0.6 mm.
Moreover, in order to obtain a stable bond, a step d) can be provided for connecting the exhaust pipe to the opening edge region by a material connection, preferably welding.
The invention will now be described with reference to the drawings wherein:
Before different embodiments and details of embodiments of a base wall of a muffler for an exhaust system of an internal combustion engine, for example in a vehicle, are explained below with reference to
The base walls 12, 18 arranged on the axial end regions 24, 16 of the circumferential wall 22 form respective end walls of the muffler housing 20 which close off the interior of the muffler at the two axial ends. The base walls 12, 18 can be connected firmly and gas tightly in their radially outer region to the circumferential wall 22 by a material connection, for example welding. Alternatively or additionally, the base walls 12, 18 providing respective end walls can be firmly and gas tightly connected to the circumferential wall 22 in the axial end regions 24, 16 by a form fit, for example by flanging.
The base walls 14, 16 arranged between the base walls 12, 18 providing the two end walls form respective intermediate walls which, together or in conjunction with the base walls 12, 18 providing end walls, divide the interior of the muffler into a total of three chambers 28, 30, 32. The base walls 14, 16 providing intermediate walls can be retained in a defined position, for example on the inner circumference of the circumferential wall 22, by clamping or/and a material connection, for example welding.
In the example illustrated, the base walls 12, 14, 16, 18 each have, in a central region, a base wall opening 34, 36, 38, 40 explained in more detail below with regard to its structure. The base wall openings 34, 36 of the base walls 12, 14 are traversed by an exhaust pipe 42 which can form, for example, an inlet pipe via which exhaust gas is fed into the interior of the muffler. The base wall openings 38, 40 of the base walls 16, 18 are traversed by an exhaust pipe 44 which can provide, for example, an outlet pipe via which exhaust gas is conducted away from the muffler 10.
The exhaust pipe 42 can, for example, be open to the chamber 28 formed between the two base walls 12, 14 and, in an axial end region of the latter, can be open to the chamber formed between the two base walls 14, 16. The chamber 28 can be connected to the chamber 30 via one or more flow-through openings formed in the base wall 14. The chamber 32 can form a resonator chamber of a Helmholtz resonator and be connected to the chamber 30 via an exhaust pipe 46 provided in the base wall 16 and providing a resonator neck.
It is noted that the structure described above with reference to
The embodiment of a base wall provided in the muffler 10 is described in detail below with reference to
The structure of such a base wall is described below, for example, with reference to the base wall 14 which forms an intermediate wall and separates two chambers 28, 30 which are connected to each other to exchange exhaust gas in the interior of the muffler.
In the embodiment of the base wall 14, which separates two chambers 28, 30 which are connected to each other to exchange exhaust gas, the opening edge region 50 can be interrupted circumferentially and, for example, be constructed with four opening edge region segments 52 following one another circumferentially and arranged with a circumferential spacing from one another, between which respective circumferential cutouts 54, via which the two chambers 28, 30 separated from each other by the base wall 14 can be connected to each other to exchange exhaust gas, are formed in the base wall 14 or the essentially plane base wall region 48.
If it is intended to provide a gastight closure by such a base wall, as is the case for example in connection with the base walls 12, 18 providing end walls or alternatively the base wall 16 providing an intermediate wall, the opening edge region 50 can be configured as an opening edge region so that it runs completely circumferentially about a respective opening center axis M of the respective base wall opening 34, 40 or 38 and is not interrupted circumferentially.
In the embodiment of
M, starting from the first bending region 56, such that, starting from the first bending region 56, the spacing of the first edge section 58 from the opening center axis M decreases essentially constantly. This means that the first edge section 58, viewed in an axial direction, is essentially not curved and of course has, for example, a circularly curved structure about the opening center axis M. A second edge section 62 adjoins the first edge section 58 in a second bending region 60. The second edge section 62 similarly has a conical or frustoconical structure such that its radial spacing from the opening center axis M increases essentially constantly starting from the second bending region 60. The opening edge region 50 thus has a structure which is essentially V-shaped in longitudinal section between a first axial end region 64 adjoining the essentially plane base wall region 48 in the region of the first bending region 56 and a second axial end region 66, remote from the base wall region 48, of the latter.
Where the two edge sections 58, 62 adjoin each other, that is, essentially in the region of the second bending region 60, the opening edge region 50 has a minimum spacing from the opening center axis M of the base wall opening 36. In the situation illustrated in
The exhaust pipe 42 is dimensioned in such a way that its predetermined external dimension A, for example also represented by the radius or twice the radius, that is, the diameter, of the exhaust pipe 42 configured, for example, with a circular cross-section is greater than the corresponding predetermined internal dimension a of the base wall opening 36. For example, the external dimension A, that is, the diameter, corresponding to twice the radius R, of the exhaust pipe 42, can be formed so that it is oversized within a range of 0.2 mm to 0.6 mm, preferably approximately 0.4 mm, with respect to the corresponding internal dimension a, that is, for example the internal diameter of the base wall opening 36.
When the muffler 10 is assembled, after the base wall 14 has been provided with the form provided therefor and possibly surrounded by the circumferential wall 22, the exhaust pipe 42 is introduced into the base wall opening 36 in the direction of the opening center axis M or the housing longitudinal axis L. Because the exhaust pipe 42 is oversized with respect to the base wall opening 36 receiving the latter, when the exhaust pipe 42 is introduced, the opening edge region 50 is spread out radially somewhat such that the exhaust pipe 42 is retained in the base wall opening 36 by a press fit and hence by a force fit. The opening edge region 50 which is spread out radially in the region of its elastic deformability, or its opening edge region segments 52, press radially inward against the outer circumference of the exhaust pipe 42 with a force F such that, on the one hand, the exhaust pipe 42 is retained in a defined position with respect to the base wall 14 and, on the other hand, a defined bearing contact on the exhaust pipe 42 is generated by the opening edge region segments 52 pressing against the outer circumference of the exhaust pipe 42 with the force F such that the occurrence of rattling noises can be prevented.
By virtue of the embodiment of the opening edge region 50 with its two edge sections 58, 62 which provide essentially a V-shaped contour of the opening edge region 50, an introduction slope, which enables the exhaust pipe 42 to be introduced easily into the base wall opening 36 and prevents it getting caught because of sharp-edged bearing contact, is formed for the exhaust pipe 42 to be received in the base wall opening 36.
It is also possible in the case of an embodiment of the opening edge region 50 with an uninterrupted form in the circumferential direction, that is, as a circumferentially continuous opening edge region, for the latter to be spread out radially when the exhaust pipe 42 is introduced into the base wall opening 36. In the case of a circumferentially closed structure of the opening edge region 50, it is advantageous if the base wall 14 is provided with a relatively low wall thickness W of no more than 1 mm, preferably no more than 0.6 mm.
In the case of such a thin-walled configuration of the base wall 14, it is ensured that, when the exhaust pipe 42 is introduced into the base wall opening 36, the circumferentially closed opening edge region 50 is correspondingly spread out because the exhaust pipe 42 is slightly oversized and, because of its elasticity, the force F which then acts radially inward essentially uniformly over the whole circumference is exerted on the exhaust pipe 42.
An alternative embodiment of the base wall 14 is illustrated in
In the embodiment illustrated in
A further alternative embodiment is illustrated in
In the embodiment illustrated in
It should finally be pointed out again that the structure, described above with reference to
In each of the above described embodiments of a base wall, it is possible to push an exhaust pipe easily by hand or using a machine through a respective base wall and introduce it into a base wall opening provided to receive an exhaust pipe, wherein the respective opening edge region is spread out and the force fit required to generate the press fit is created. When a muffler constructed in this way is operating, the different components of the latter heat up and expand such that the press fit or the force exerted on an assigned exhaust pipe by a respective opening edge region increases and an even stronger retaining effect is generated.
It is understood that the foregoing description is that of the preferred embodiments of the invention and that various changes and modifications may be made thereto without departing from the spirit and scope of the invention as defined in the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2021 116 802.3 | Jun 2021 | DE | national |
