Patent Publication Number: US-11384665-B2

Title: Muffler

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of priority under 35 U.S.C. § 119 of German Application 10 2018 115 742.8, filed Jun. 29, 2018, the entire contents of which are incorporated herein by reference. 
     TECHNICAL FIELD 
     The present invention pertains to a muffler, which can be provided in a vehicle, for example, as a rear muffler in an exhaust system of an internal combustion engine. 
     TECHNICAL BACKGROUND 
     Using muffling units, which are also called “bombs” and comprise an exhaust-gas-carrying inner pipe, an outer pipe enclosing this inner pipe and muffling material arranged in an intermediate space between the inner pipe and the outer pipe, is known for lowering the noise level as much as possible. 
     SUMMARY 
     An object of the present invention is to provide a muffler, especially a rear muffler, for an exhaust system of an internal combustion engine, in which a simplified assembly of the various components or assembly units of same is made possible. 
     This object is accomplished according to the present invention by a muffler, especially rear muffler, for an exhaust system of an internal combustion engine, comprising a muffler housing with a housing jacket elongated in the direction of a housing longitudinal axis and with an outer panel connected to the housing jacket at both axial end areas of the housing jacket, wherein the housing jacket defines with the outer panel a muffler interior, and at least one inner panel dividing the muffler interior is arranged in the muffler interior, further comprising a muffling unit with an exhaust-gas-carrying inner pipe, with an outer pipe enclosing the inner pipe and muffling material arranged between the inner pipe and the outer pipe, wherein the inner pipe is accommodated in an opening of an inner panel and in an opening of one of the outer panels or of an additional inner panel, and the outer pipe is permanently connected to the inner panel or/and to one of the outer panels or to the additional inner panel. 
     Because the muffling unit is connected in this muffler configured according to the present invention via the outer pipe to an inner panel or/and to one of the outer panels or to at least one of two inner panels, through which the inner pipe passes, it is not necessary to establish a direct connection of the outer pipe to the inner pipe. This simplifies the configuration, because the muffling unit can be manufactured in a simple manner with the inner pipe, the outer pipe and the muffling material, e.g., by the intermediate space formed between the inner pipe and the outer pipe being filled with the muffling material after the inner pipe is positioned in the outer pipe. Additional actions for establishing a permanent connection of the outer pipe to the inner pipe are not necessary. 
     For example, a permanent integration of the muffling unit can be guaranteed by the outer pipe being connected by welding to the inner panel or/and to one of the outer panels or to an additional inner panel. 
     In order to be able to ensure the defined positioning of the outer pipe in relation to the inner panel, on the one hand, and of one of the outer panels or of the additional panel, on the other hand, in a simple manner, an axial bulge accommodating the outer pipe may be formed in the inner panel or/and in one of the outer panels or in the additional inner panel. Provisions are preferably made here for the axial bulge formed in the inner panel and the axial bulge formed in one of the outer panels or in the additional inner panel to be oriented axially away from one another for a simple accommodation of the muffling unit. 
     Provisions may advantageously be made here for the opening provided in the inner panel to be provided in the area of the axial bulge formed in the inner panel, or/and for the opening formed in one of the outer panels or in the additional inner panel to be provided in the area of the axial bulge formed in one of the outer panels or in the additional inner panel. 
     In order to also ensure a permanent and defined positioning of the inner pipe in a simple manner, a neck, which encloses the inner pipe, is oriented axially away in the direction of the axial bulge provided in the inner panel and encloses the opening formed in the inner panel, may be provided at the inner panel, or/and that a neck, which encloses the inner pipe, is oriented axially away in the direction of the axial bulge provided in the outer panel or in the additional inner panel and encloses the opening formed in the outer panel or in the additional inner panel, may be provided at one of the outer panels or the additional inner panel. Because the neck is oriented axially away in the direction of a respective bulge, i.e., it is not positioned in a manner meshing with the interior provided by the bulge, in which interior the outer pipe and also the muffling material can be positioned in a meshing manner, a mutual interference of such a neck especially with the muffling material can be avoided. 
     A permanent connection of the inner pipe can be achieved here by the inner pipe being permanently connected, preferably by welding, to the neck provided at the inner panel, or/and by the inner pipe being permanently connected, preferably by welding, to the neck provided at one of the outer panels or at the additional inner panel. Further, provisions may be made for a simple configuration for the neck provided at the inner panel and for the neck provided at one of the outer panels or at the additional inner panel to be oriented axially away from one another. 
     For a simple configuration, the outer pipe may have a radial distance to the inner pipe in each of its axial end areas, or/and that the outer pipe have a cylindrical configuration. 
     In order to be able to make use of the muffling characteristic of the muffling material efficiently, a plurality of openings passing through a pipe wall of the inner pipe may be provided in the length area of the inner pipe, which length area is enclosed by the muffling material. 
     For an efficient reduction of the noise level, it is further provided that the muffling material essentially entirely fill up an intermediate space formed between the outer pipe and the inner pipe. 
     For example, the muffling material may comprise fiber material or/and foamed material. 
     The inner panel or/and one of the outer panels or the additional inner panel may be provided in a simple manner as a shaped sheet metal part having the structure to be provided according to the present invention. 
     The present invention further pertains to an exhaust system, comprising a muffler that is configured according to the present invention. 
     The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its uses, reference is made to the accompanying drawings and descriptive matter in which preferred embodiments of the invention are illustrated. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the drawings: 
         FIG. 1  is a simplified longitudinal sectional view showing a length area of a muffler for an exhaust system of an internal combustion engine. 
     
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
     Referring to the drawings,  FIG. 1  shows an end area of a muffler, which is generally designated by  10 , for an exhaust system of an internal combustion engine in a vehicle. For example, such a muffler  10  may be provided as a rear muffler in the end area of the exhaust system. 
     The muffler  10  comprises a muffler housing  12  with a housing jacket  14 , which is, for example, essentially cylindrical and is elongated in the direction of a housing longitudinal axis A. This muffler is permanently connected, for example, by flanging or/and welding, to outer panels  16 ,  16 ′ at both axial end areas of the housing jacket  14 , so that the housing jacket  14  defines with the two outer panels  16 ,  16 ′ a housing interior  18 . 
     An inner panel  20 , which is at an axial distance to the outer panel  16 , is provided in the housing interior  18  in the example shown. The inner panel  20  divides the housing interior  18  into a plurality of space areas, so that a chamber  22  is formed between the outer panel  16  and the inner panel  20  shown in the exemplary embodiment being shown. The inner panel  20  may have, for example, a perforation, for the sake of muffling, so that the chamber  22  is open to the remaining area of the housing interior  18  and thus can form a resonator chamber. 
     A muffling unit generally designated by the reference number  24  comprises an exhaust-gas-carrying inner pipe  26  as well as an outer pipe  28 , which encloses the inner pipe  26  and has an essentially cylindrical shape. An intermediate space  30  formed between the inner pipe  26  and the outer pipe  28  is essentially entirely filled with muffling material  32 . 
     The muffling unit  24  may be provided as a preassembled assembly unit for the muffler  10 . The inner pipe  26  may be positioned in the outer pipe  28  for this and the intermediate space  30  formed between them can then be filled with the muffling material  32 . The muffling material  32  may be, for example, foamed material, which is injected into the intermediate space  30  after the defined positioning of the inner pipe  26  in relation to the outer pipe  28 . The muffling material  32  may, as an alternative, also comprise fiber material, which is stuffed into the intermediate space  30  or can be wound around the inner pipe  26 , for example, in the form of a fiber mat before inserting the inner pipe  26  into the outer pipe  28  and can then be inserted together with the inner pipe  26  into the outer pipe  28 . 
     It is seen that due to its cylindrical shape, the outer pipe  28  has a radial distance to the inner pipe  26  in its two axial end areas  34 ,  36  as well as in the length areas located between them and in particular is not directly connected to this inner pipe  26  in any length area. A holding together of this muffling unit  24  is guaranteed via the muffling material  32  arranged between the inner pipe  26  and the outer pipe  28 . In order to be able to efficiently utilize the muffling characteristic of the muffling material  32 , a perforation with a plurality of openings  35  passing through a pipe wall  33  of same is provided in the inner pipe  26 . 
     In the case of the muffler  10  shown in  FIG. 1 , the muffling assembly unit  24  is arranged between the outer panel  16  shown in this FIGURE and the inner panel  20  arranged at an axial distance thereto and is held on it. The outer panel  16  has for this purpose an axial bulge  38 , which is dimensioned and adapted to the circumferential contour of the outer pipe  28  such that this outer pipe  28  can be inserted with light press fit with its axial end area  34 , for example, axially into the axial bulge  38  or into the space area formed therein. An opening  40 , which is enclosed by a neck  42 , which is likewise provided at the outer panel  16 , is formed at the outer panel  16  in an area located centrally in the axial bulge  38 . The inner pipe  26 , protruding axially over the outer pipe  28  or the muffling material  32 , meshes, with its axial end area  44 , with the opening  40  or with the neck  42 . Here as well, the dimensioning of the opening  40  and of the neck  42  may be selected or coordinated with the outer circumferential contour of the inner pipe  26  in its axial end area  44  such that the inner pipe  26  is accommodated with slight press fit in the opening  40  or in the neck  42 , and possibly also protrudes over the neck  42  slightly outwards. Because the neck  42  is oriented axially away in the direction of the bulge  38  and does not mesh with the bulge  38  or with the interior provided by this bulge  38 , there is no interaction between the neck  42  and the muffling material  32  positioned in a manner meshing with the bulge, which interaction makes the assembly difficult. 
     An axial bulge  46  is also provided in the inner panel  20 . This bulge  46  is oriented away from the axial bulge  38  provided in the outer panel  16  and accommodates the axial end area  36  of the outer pipe  28  or the part of the muffling material  32  also provided in this axial end area  36  of the outer pipe  28 . Here as well, the axial bulge  46  is preferably adapted in terms of shape and dimensioning to the shape and dimensioning of the outer pipe  28  in its axial end area  36 , so that the outer pipe  28  with its axial end area  36  can be accommodated with slight press fit in the axial bulge  46 . 
     An opening  48  accommodating an end area  49  of the inner pipe  26  and through which this inner pipe  26  passes, is provided in the central area of the axial bulge  46  of the inner panel  20  and is enclosed by a neck  50  formed at the inner panel  20  and extending approximately axially. The neck  50  is oriented away from the axial bulge  46 , i.e., the interior formed in this bulge  46 , so that here as well there is no mutual interference with the area of the muffling material  32 , which area meshes with the axial bulge  46 . In particular, it is seen that the neck is also oriented away from the outer panel  16 , so that the neck  42  provided at the outer panel  16  and the neck  50  provided at the inner panel  20  are oriented away from one another. 
     A permanent holding together of the different components and assembly units can be achieved by connection in substance, i.e., for example, by welding. Thus, the inner panel  20  is preferably fixed to the housing jacket  14  by a weld  52 , for example, a continuous weld seam or a plurality of welding spots. To ensure a tight closure against the discharge of exhaust gas, the inner pipe  26  is fixed in an inner pipe axial end area to the outer panel  16 , preferably to the neck  42  of same, by a weld  52 , preferably a continuous weld seam. In a corresponding manner, even though this is not absolutely necessary for the sake of passage of exhaust gas, the inner pipe  26  in an inner pipe other axial end area  49  may also be fixed to the inner panel  20 , preferably to the neck  50  of same, by a weld  56 , preferably again by a continuous weld seam. In particular, a connection in substance of the outer pipe  28  to the panel  20  in the area of a weld  58 , which can preferably in turn be configured as a continuous weld seam or a plurality of welding spots arranged at spaced locations from one another, ensures a permanent connection of the muffling assembly unit  24 . As an alternative or in addition, the outer pipe  28  can be fixed to the outer panel  16  by a weld  60 , wherein the weld  60  may also comprise a continuous weld seam or a plurality of welding spots arranged at spaced locations from one another. If the outer pipe  28  is fixed in the outer pipe two axial end areas  34 ,  36  to the outer panel  16  and to the inner panel  20  by welding, as a result of which a relatively rigid connection of these two panels to one another is established as well, it may be advantageous not to connect the inner pipe  26  in the inner pipe end area  49  rigidly to the inner panel  20  because of the different thermal expansions of the inner pipe  26 , on the one hand, and of the outer pipe  28 , on the other hand, which are to be expected during the operation. 
     A stable hold of the muffling unit  24  in the muffler  10  is guaranteed by the permanent connection of the outer pipe  28  at the inner panel  20  or/and at the outer panel  16 , each adjoining the respective axial bulge  38  or  46  formed therein. This can be supported by the permanent connection of the inner pipe  26  in at least one of its two end areas  44 ,  49  at the outer panel  16  or at the inner panel  20 . 
     It should be pointed out that the principles of the present invention may also be utilized when the muffling unit  24  is carried or fixed in its two axial end areas or in the two axial end areas  34 ,  36  of the outer pipe  28  at two inner panels  20 ,  20 ′ arranged in the housing interior  18  of the muffler  10 . 
     While specific embodiments of the invention have been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles.