Patent Publication Number: US-7913811-B2

Title: Muffler and corresponding manufacturing process

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of priority under 35 U.S.C. §119 of German Patent Application DE 10 2008 056 350.1 filed Nov. 7, 2008, the entire contents of which are incorporated herein by reference. 
     FIELD OF THE INVENTION 
     The present invention pertains to a muffler for an exhaust system of an internal combustion engine, especially of a motor vehicle. In addition, the present invention pertains to a process for manufacturing such a muffler. 
     BACKGROUND OF THE INVENTION 
     A muffler may be designed as a jacketed embodiment for certain intended uses. In this case, it has a housing, which has a jacket and two end bottoms, which are arranged at two mutually spaced longitudinal ends of the jacket. Depending on the installation situation, the muffler may have at least one jacket opening, which passes through the jacket and through which an inner tube arranged in the interior of the housing can be connected to a tube of the exhaust system. Such a configuration may be advantageous, for example, if the muffler is arranged transversely in the mounted state. In addition, provisions may now also be made for providing at least one of the end bottoms with a bottom opening, through which another tube arranged in the interior space of the housing can be connected to another tube of the exhaust system. 
     The embodiment of the jacket opening and the embodiment of the connection through the jacket opening is problematic in mufflers of a jacketed design. To make the connection gas-tight, it is desirable to arrange the inner tube such that it is led from the inside through the jacket opening to the outside, so that it is accessible and, for example, can be welded from the outside. However, this makes it difficult to introduce the interior tube into a prefabricated jacket. A later attachment of the jacket is likewise complicated. 
     SUMMARY OF THE INVENTION 
     The present invention pertains to the object of proposing an improved embodiment for a muffler of the type mentioned in the introduction and for a corresponding manufacturing process, which embodiment is characterized especially in that the muffler can be manufactured in a comparatively simple manner. 
     According to the invention, a muffler is provided for an exhaust system, particularly for a motor vehicle internal combustion engine. The muffler comprises a housing with a jacket with an end bottom at each of two mutually spaced longitudinal ends of jacket. The jacket has at least one jacket opening passing through the jacket. An inner tube is arranged in the interior of housing. The jacket opening is for connecting the inner tube to a tube of the exhaust system. The jacket is segmented in a circumferential direction and comprises a jacket segment and a remaining jacket. The jacket segment is manufactured as a separate component in relation to the remaining jacket. The separate component jacket segment is rigidly connected to the remaining jacket and has the at least one jacket opening. 
     The present invention is based on the general idea of forming at least one jacket opening on a jacket segment, which forms a separate component in respect to the remaining jacket. The inner tube can thus be joined to this jacket segment in order to embody a connection of high quality between the inner tube and the jacket opening. A unit, which can be completely preassembled and can be subsequently complemented with the remaining jacket, is created as a result. Since the jacket segment extends only along a part of the circumference of the jacket, handling during manufacture is extremely simplified, so that it is possible, in particular, to use simpler and less expensive manufacturing tools. 
     Corresponding to a special embodiment, at least one intermediate bottom, which is fastened from the inside to an inner side of the jacket segment, which inner side faces the interior of the housing, may be arranged in the interior of the housing. Fastening performed from the inside between the bottom and the jacket segment can be embodied with a considerably higher quality and reliability than a connection to be prepared from the outside. This is made possible by the fact that the remaining jacket is attached only at a later point in time, so that the inner side of the jacket segment is readily accessible during the manufacture of the aforementioned unit. 
     Corresponding to another advantageous embodiment, the jacket segment may have a collar, which is formed integrally thereon, projects to the outside and borders the jacket opening, and, in addition, the inner tube may axially protrude into the collar and end, for example, more or less flush with same. A gas-tight connection can be established by these measures between the inner tube and the collar in an especially simple manner, as a result of which the jacket opening can be sealed in an especially simple manner and with an especially high quality. At the same time, the connection to the exhaust system can also be embodied in a simple and gas-tight manner due to this mode of construction. For example, a tube of the exhaust system can be inserted into or attached to the inner tube and rigidly and tightly connected to the inner tube and/or to the collar by means of a circumferential weld seam. 
     It is apparent that the above-described features, which will also be explained below, can be used not only in the particular combination described, but in other combinations or alone as well, without going beyond the scope of the present invention. 
     Preferred exemplary embodiments of the present invention are shown in the drawings and will be explained in more detail in the following description, where identical reference numbers designate identical or similar or functionally identical components. 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 a preferred embodiment of the invention is illustrated. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the drawings: 
         FIG. 1  is a perspective view showing a muffler according to the invention; 
         FIG. 2  is a perspective view of a jacket segment of the muffler; 
         FIG. 3  is a perspective view of an insert of the muffler; 
         FIG. 4  is a perspective view of a prefabricated unit of the muffler; 
         FIG. 5  is a perspective view of another jacket segment of the muffler; and 
         FIG. 6  is a perspective view of the muffler during the mounting of the other jacket segment on the preassembled unit. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to the drawings in particular, corresponding to  FIGS. 1 through 6 , a muffler  1 , which is suitable for being integrated into an exhaust system, not shown here, of an internal combustion engine, especially of a motor vehicle, comprises a housing  2  of a jacket type design. The housing  2  correspondingly has a jacket  3 , which extends in a longitudinal direction  4  and in a circumferential direction  5 . The housing  2  has, furthermore, two end bottoms, or end pieces,  6 , which are arranged at mutually spaced longitudinal ends of the jacket  3 . The housing  2  has at least one jacket opening  7 , which passes through the jacket  3  and forms an exhaust gas inlet or an exhaust gas outlet. An inner or radial tube  8  arranged in the interior of housing  2  can be connected by said jacket opening  7  to a tube of the exhaust system, which said tube is not shown here. The housing  2  has at least one additional opening. This at least one additional opening is designed in the preferred example as a bottom opening  9 , which passes through one of the end bottoms, or end pieces,  6  and through which another tube  10  arranged in the interior of housing  2  can likewise be connected to another tube of the exhaust system. This bottom opening  9  maybe, complementary to the jacket opening  7 , an exhaust gas outlet or an exhaust gas inlet. Two such bottom openings, which may be formed at the same end bottom  6  or are preferably arranged each on one of the end bottoms  6 , may be present, in principle. Only a single jacket opening  7  is preferably formed on the housing  2 . For example, the muffler  2  may be designed as a rear muffler. It is especially suitable for transverse mounting on the underbody of the vehicle. 
     The jacket  3  is segmented in the circumferential direction  5 , so that it has at least two jacket segments, namely, a first jacket segment  11  and a second jacket segment  12 . The first jacket segment  11  has the jacket opening  7  and will hereinafter be called jacket segment  11  for simplicity&#39;s sake. The second jacket segment  12  forms the remaining jacket  3  and will hereinafter be called remaining jacket  12 . The jacket segment  11  is designed as a separate component relative to the remaining jacket  12 . The jacket segment  11  and the remaining jacket  12  are rigidly connected to one another in the mounted state, which is shown in  FIG. 1 . The remaining jacket  12  preferably has no jacket opening. If a plurality of jacket openings  7  are present, these are all preferably formed in jacket segment  11 . 
     Jacket segment  11  may have, corresponding to the embodiments being shown here, a collar  13 , which projects to the outside relative to the rest of the outer contour of the jacket segment  11  and which borders the jacket opening  7 . Collar  13  is made integrally in one piece with the jacket segment  11 . The jacket segment  11  may be designed especially as a shaped sheet metal part, especially as a deep-drawn part. The inner or radial tube  8  associated with the jacket opening  7  protrudes coaxially into the jacket opening  7 . The inner or radial tube  8  ends more or less flush with the collar  13  in the example. The inner tube  8  may be rigidly connected to the collar  13  in the mounted state. An annular, closed circumferential weld seam is suitable for this. In an inner tube  8  slightly projecting over the collar  13 , this seam may connect a front side of collar  13  to the outer side of the inner tube  8 . The jacket segment  11  is preferably made in one piece here. 
     A process for manufacturing the muffler  1  will be described in more detail below with reference to  FIGS. 2 through 6 . Other features of the muffler  1  will be explained in more detail. 
     According to  FIG. 2 , the jacket segment  11  is manufactured separately from the remaining jacket  12  or is separated from same. At any rate, the jacket segment  11  and the remaining jacket  12  are separate components after their manufacture. A one-part manufacture of the jacket segment  11  as a shaped sheet metal part is preferable. As can be recognized, collar  13  is made integrally in one piece with the jacket segment  11 . The jacket segment  11  preferably extends over between 10% and 40% of the overall circumference of the jacket  3 . It extends over about 20% of the overall length of the jacket  3  in the example. As can be recognized, circumferential ends  14  of jacket segment  11  always extend in a straight line. They preferably extend in parallel to the longitudinal direction  4  of the jacket  3 . 
     An insert  15 , shown in  FIG. 3 , which comprises at least the inner or radial tube  8  and the two end bottoms  6 , is manufactured separately from jacket segment  11  and separately from the remaining jacket  12 .  FIG. 3  shows a comparatively complex insert  15 , which also comprises an internal arrangement having at least three intermediate bottoms  16 , the additional inner tube  10  as well as at least one connection tube  17 . A plurality of chambers, which may be designed as reflection chamber, absorption chamber and resonance chamber as well as any desired combinations thereof, may be formed by means of this insert  15  in the interior of housing  2 . Insert  15  can be completely preassembled per se. 
     According to  FIGS. 3 and 4 , the completely preassembled insert  15  may be rigidly connected to the jacket segment  11  in order to form a unit  18 , which can be completely preassembled. Mounting of the jacket segment  11  on the insert  15  is comparatively simple, because positional tolerances, in particular, can be compensated in an especially simple manner. Furthermore, the inner tube  8  can be passed through the jacket opening  7  and connected to the collar  13  in an especially simple manner. The end bottoms  6  can also be connected to the jacket segment  11  in a simple manner, and shape tolerances and positional tolerances can be compensated in a simple manner in this case as well. According to  FIG. 4 , it is easy to recognize that an inner side of the jacket segment  11  facing the interior of the housing  2  is easily accessible in this unit  18  because of the absence of the remaining jacket  12 . Consequently, the intermediate bottoms  16 , for example, can be attached to the jacket segment  11  from the inside. For example, the intermediate bottoms  16  can be welded to the inner side of the jacket segment  11 . The unit  18  acquires an especially high stability as a result. 
     Corresponding to  FIG. 5 , the remaining jacket  12  is manufactured separately from the jacket segment  11  and separately from insert  15 . This is likewise preferably a shaped sheet metal part, which is preferably manufactured from one piece. The remaining jacket  12  likewise has, complementarily to the jacket segment  11 , straight circumferential ends  19 , which preferably extend in parallel to the longitudinal direction  4  of jacket  3 . Especially advantageous here is an embodiment in which the remaining jacket  12  is larger in the circumferential direction  5  than the difference between the overall circumference of the jacket  3  and the circumferential portion of the jacket segment  11 . An overlapping area  20  each, which overlaps the jacket segment  11  at the circumferential ends  14  thereof in the circumferential direction  5 , can be embodied hereby at the circumferential ends  19  of the remaining jacket  12 . To make it possible to make this overlap as gas-tight as possible and to prepare it in as simple a manner as possible, the jacket segment  11  or, like here, the remaining jacket  12  may have an outwardly stepped edge  21  each at its circumferential ends  19 . The step height of the stepped edge  21  is coordinated with the thickness of the material of jacket segment  11 . Besides, the overlapping area  20  makes it possible to compensate tolerances during the mounting of the remaining jacket  12 . 
     The remaining jacket  12 , which may be preformed corresponding to the circumferential contour of the jacket  3  or corresponding to the circumferential contour of unit  18 , is attached to unit  18  corresponding to  FIG. 6 . The remaining jacket  12  may be attached for this at right angles to the longitudinal direction  4 , and the open side  22  formed by the missing jacket segment  11  is pulled over unit  18 . This is readily possible due to the flexibility of the jacket material used. The remaining jacket  12  is positioned now at unit  18  such that the overlapping areas  20  overlap the circumferential ends  14  of the jacket segment  11 . The remaining jacket  12  can subsequently be attached. For example, the remaining jacket  12  may be rigidly connected to the jacket segment  11  along the stepped edges  21 . For example, a weld seam prepared from the outside may be provided. Furthermore, the remaining jacket  12  is rigidly connected to the end bottoms  6 , for example, by means of weld seams. Moreover, the remaining jacket  12  may be additionally connected rigidly to at least one of the intermediate bottoms  16  from the outside. For example, tack welds prepared from the outside may connect the remaining jacket  12  from the outside to the intermediate bottoms  16  arranged on the inside. 
     The muffler according to  FIG. 1  is now obtained after attaching the remaining jacket  12 . 
     Besides, it is possible due to the segmenting of the jacket  3  in the circumferential direction  5  to vary the material thicknesses or wall thicknesses of the jacket  3  in the individual segments. Thus, the jacket segment  11  and the remaining segment  12  may have different wall thicknesses. For example, the jacket segment  11  has a greater wall thickness than the remaining jacket  12 . For example, the wall thickness of the jacket segment  11  may be at least 50% of or at least twice the wall thickness of the remaining jacket  12 . As a result, the jacket segment  11  can be provided with greater dimensional stability, which increases the rigidity of unit  18 . At the same time, the muffler  1  is optimized in terms of weight and manufacturing costs. In addition or as an alternative, it is possible to use different materials for the jacket segment  11  and the remaining jacket  12 . Adaptation to different requirements, e.g., strength, stiffness, is made possible hereby as well. 
     In addition or as an alternative, it is possible due to the segmentation in a relatively simple manner to provide the jacket segment  11  or the remaining jacket  12  or both the jacket segment  11  and the remaining jacket  12  with stiffening beads, which are not shown here. The stability of the jacket or of housing  2  can be significantly increased hereby. The beads preferably extend in the circumferential direction  5 . They may be arranged especially such that they can be used to position the intermediate bottoms  16  and/or the end bottoms  6 , e.g., in the form of groove-like depressions on the inner side of the jacket segment  11  and of the remaining jacket  12 . 
     While a specific embodiment of the invention has been 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.