Muffler and method for manufacturing same

Abstract

An internal combustion engine exhaust system muffler (1) has a housing (2) within which two chambers (3) are formed with an inner panel (4) arranged therebetween. The inner panel (4) has at least one collar (8) at the edge, which has an outer side (9) facing the housing (2), and wherein the housing (2) has, on an inner side (11), in the area of the inner panel (4), at least one contour (12), which faces the collar (8) and with which the collar (8) is in contact. Reduced noise generation, reduced wear as well as prolonged service life can be achieved with the outer side (9) of the collar (8) forming a cone structure (10) in profile and the contour (12) of the housing (2) forms a cone structure seat (13) with a complementary cone profile and with which the cone (10) is flatly and non-positively in contact.

Claims

1. A muffler for an exhaust system of an internal combustion engine, the muffler comprising: an inner panel; and a housing, the inner panel being arranged in the housing and cooperating with the housing to form at least two chambers, with the inner panel between the at least two chambers, wherein: the inner panel has at least one collar with an edge, which has an outer side, which faces the housing and forms a cone structure which is a cone, partial cone or frustoconical shaped in profile; and the housing has an inner side, in an area of the inner panel, with at least one contour, which faces the collar and forms a cone structure seat which is a cone, a partial cone or frustoconical shaped seat in profile, which is complementary to the cone structure and with which the cone structure is flatly and loosely in contact, wherein the cone structure and cone structure seat form a conical sliding fit, which permits a relative axial adjustment and a relative radial adjustment between the inner panel and the housing and makes possible the flat contact between the cone and cone structure seat.

2. A muffler in accordance with claim 1, wherein the inner panel has only a single collar extending circumferentially in the closed form.

3. A muffler in accordance with claim 1, wherein the inner panel has a plurality of collars or collar segments extending distributed in a circumferential direction of the inner panel.

4. A muffler in accordance with claim 1, wherein the inner panel is axially prestressed with the cone structure in contact with cone structure seat in an axially prestressed state.

5. A muffler in accordance with claim 1, wherein the housing is mounted in a radially inwardly mounted state so that the inner panel is bulged elastically at least at a mounting temperature and the cone structure is in contact with cone structure seat in a prestressed state.

6. A muffler in accordance with claim 1, further comprising at least one exhaust pipe is fastened to the housing and fastened to the inner panel.

7. A muffler in accordance with claim 6, wherein the exhaust pipe is mounted in an axially prestressed state with the inner panel bulged elastically at least at a mounting temperature and the cone structure is in contact with cone structure seat in a prestressed state.

8. A muffler in accordance with claim 6, wherein the inner panel or the exhaust pipe or both the inner panel and the exhaust pipe are comprised of a first material, which has a first coefficient of thermal expansion, which is lower than a second coefficient of thermal expansion of a second material, of which the housing is comprised.

9. A muffler in accordance with claim 6, wherein the inner panel or the exhaust pipe or both the inner panel and the exhaust pipe are comprised and the housing are comprised of the same material.

10. A muffler in accordance with claim 1, wherein: the cone structure and the cone seat structure have a cone angle, in relation to the axial direction, that is a function of coefficients of thermal expansion of the housing and of the inner panel or exhaust pipe whereby a radial expansion of the housing relative to the inner panel is compensated by an axial expansion of the exhaust pipe in relation to the housing in the conical sliding fit whereby flat contact is preserved between the cone and cone structure seat.

11. A muffler in accordance with claim 1, wherein the housing is configured as a shell construction.

12. A muffler in accordance with claim 1, wherein in the area of the inner panel, the housing has a depression on an inner side, with which said depression the collar meshes and in which the contour that forms the cone structure seat in profile is located.

13. A muffler in accordance with claim 1, wherein in an area of the inner panel the housing has, on an inner side, an elevation, at which the contour forming the cone structure seat in profile is located.

14. A method for manufacturing a muffler comprising an inner panel, a housing, the inner panel being arranged in the housing and cooperating with the housing to form at least two chambers, with the inner panel between the at least two chambers, wherein the inner panel has at least one collar with an edge, which has an outer side, which faces the housing and forms a cone structure which is a cone, partial cone or frustoconical shaped in profile, the housing has an inner side, in an area of the inner panel, with at least one contour, which faces the collar and forms a cone structure seat which is a cone, a partial cone or frustoconical shaped seat in profile, which is complementary to the cone structure and with which the cone structure is flatly and loosely in contact and the cone structure and cone structure seat form a conical sliding fit, which permits a relative axial adjustment and a relative radial adjustment between the inner panel and the housing and makes possible the flat contact between the cone and cone structure seat, the method comprising the steps of: inserting the inner panel into a lower shell of the housing; placing an upper shell on the lower shell, with the inner panel bulged elastically; and fastening the upper shell to the lower shell, while the inner panel is bulged elastically, whereby the housing is subsequently mounted in a radially inwardly prestressed state.

15. A method for manufacturing a muffler, the muffler comprising an inner panel, a housing, the inner panel being arranged in the housing and cooperating with the housing to form at least two chambers, with the inner panel between the at least two chambers, wherein the inner panel has at least one collar with an edge, which has an outer side, which faces the housing and forms a cone structure which is a cone, partial cone or frustoconical shaped in profile, the housing has an inner side, in an area of the inner panel, with at least one contour, which faces the collar and forms a cone structure seat which is a cone, a partial cone or frustoconical shaped seat in profile, which is complementary to the cone structure and with which the cone structure is flatly and loosely in contact and the cone structure and at least one exhaust pipe fastened to the housing and fastened to the inner panel, wherein the cone structure and cone structure seat form a conical sliding fit, which permits a relative axial adjustment and a relative radial adjustment between the inner panel and the housing and makes possible the flat contact between the cone and cone structure seat, the method comprising the steps of: inserting the inner panel with the exhaust pipe fastened thereto into a lower shell of the housing; placing an upper shell of the housing on the lower shell of the housing; pushing the exhaust pipe radially inwardly until the inner panel bulges elastically; and fastening the exhaust pipe to the housing while the inner panel is bulged elastically, whereby the exhaust pipe is subsequently mounted in an axially inwardly prestressed state.

16. A muffler for an exhaust system of an internal combustion engine, the muffler comprising: an inner panel comprising an outer periphery with at least one collar with a sloped collar edge surface or ramp contour collar edge surface; a housing with an inner side with at least one seat contour surface, which faces the at least one collar edge surface and has a sloped or ramp contour which is complementary to the collar edge surface, wherein the inner panel is arranged in the housing and cooperates with the housing to form at least two chambers, with the inner panel between the at least two chambers and with the sloped collar edge surface or ramp contour collar edge surface in abutting non-positive contact with the seat contour surface, wherein the cone structure and cone structure seat form a conical sliding fit, which permits a relative axial adjustment and a relative radial adjustment between the inner panel and the housing and makes possible the flat contact between the cone and cone structure seat.

17. A muffler in accordance with claim 16, wherein the inner panel is axially prestressed relative to the housing, with the sloped collar edge surface or ramp contour collar edge surface in contact with seat contour surface in an axially prestressed state.

18. A muffler in accordance with claim 16, wherein the housing is mounted in a radially inwardly mounted state so that the inner panel is bulged elastically at least at a mounting temperature and the sloped collar edge surface or ramp contour collar edge surface is in contact with the seat contour surface in a prestressed state.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In the drawings:

(2) FIG. 1 is a highly simplified longitudinal sectional view of a muffler according to the section lines I-I in FIG. 2;

(3) FIG. 2 is a highly simplified cross sectional view of the muffler corresponding to the section lines II-II in FIG. 1, but in two different embodiments A and B;

(4) FIG. 3 is an enlarged detail view in the longitudinal section in an initial state;

(5) FIG. 4 is a view as in FIG. 3, but in an operating state;

(6) FIG. 5 is a view as in FIG. 3, but during a mounting operation;

(7) FIG. 6 is a view as in FIG. 5, but after the mounting operation;

(8) FIG. 7 is a view as in FIG. 5, but during another mounting operation; and

(9) FIG. 8 is a view as in FIG. 7, but after the another mounting operation.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

(10) Referring to the drawings, corresponding to FIGS. 1 through 8, a muffler 1, which is intended for use in an exhaust system of an internal combustion engine, preferably of a motor vehicle, comprises a housing 2, in which at least two chambers 3 are formed, wherein an inner panel 4 is provided between two chambers 3 each in the housing 2. The housing 2 contains exactly three chambers 3 in the example, which can be designated, for distinction, according to the arrangement shown in FIG. 1, by 3l for the left chamber, by 3r for the right chamber and 3m for the middle chamber. Two inner panels 4, which may also be called left inner panel 4l and right inner panel 4r according to their arrangement in FIG. 1, are correspondingly present in case of three chambers 3.

(11) In addition, the muffler 1 is equipped in the example with at least one exhaust pipe 5, which is fastened to the housing 2 at one end and to such an inner panel 4 at the other end. The muffler 1 has four such exhaust pipes 5 in the example, and only two such exhaust pipes 5 each can be seen in the sectional views shown in FIGS. 1 and 2. A possible section plane I-I of the sectional view in FIG. 1 is indicated in FIG. 2. In case of a hypothetical flow of exhaust gas through the muffler 1 from left to right according to the arrows 7 in FIG. 1, two inlet pipes 5e as well as two outlet pipes 5a are correspondingly provided. The inlet pipes 5e pass through the left chamber 3l and open in an open form into the middle chamber 3m. The outlet pipes 5a pass through the right chamber 3r and are arranged in the open form in the middle chamber 3m. The middle chamber 3m is used here as an expansion chamber as well as an overflow chamber in order to guide the exhaust gas from the inlet pipes 5e to the outlet pipes 5a. The left chamber 3l and the right chamber 3r are used here each as expansion chambers and are filled each with a sound-absorbing material 6 for this. This sound-absorbing material 6 is not shown in the sectional view shown in FIG. 2. At least one of the inlet pipes 5e and/or at least one of the outlet pipes 5a may be provided with a perforation for an acoustic coupling of the absorption chambers 3l and 3r. An embodiment in which the exhaust pipes 5 are not perforated is likewise possible. The acoustic coupling is brought about now via a perforation 20 in the respective inner panel 4, which said perforation can be seen in FIG. 2 and is formed as an example by a plurality of openings. The absorption chambers 3l, 3r are thus coupled acoustically through the perforated inner panels 4l, 4r with the expansion chamber 3m, which is, in turn, coupled elastically with the exhaust stream 7 via the exhaust pipes 5. Further, a combination of the two variants is also possible, so that, on the one hand, the left chamber 3l is coupled acoustically through a perforated inlet pipe 5e and a perforated left inner panel 4l and/or, on the other hand, the right chamber 3r is coupled acoustically through a perforated outlet pipe 5a and a perforated right inner panel 4r.

(12) The respective inner panel 4 has at least one collar 8 at the edge, which has an outer side 9 facing the housing 2. According to the longitudinal sections shown in FIG. 1 as well as 3 through 8, this outer side 9 forms a cone structure (a cone, partial cone or frustoconical shape in profile) 10. The housing 2 has at least one contour 12 facing the collar 8 on its inner side 11 facing the chambers 3 in the area of the respective inner panel 4. In the profile of the sectional views, this contour 12 forms a cone, partial cone or frustoconical shaped seat 13, which is complementary to the cone structure 10 and with which the cone structure 10 is in contact flatly (with a complementary contour) and loosely, preferably in a non-positive (not fixed) manner. As can be seen, the cone 12 and the cone, partial cone or frustoconical shaped seat 13 taper axially in the direction in which the exhaust pipe 5 connected to the corresponding inner panel 4 expands during heating.

(13) The sectional view according to FIG. 2 shows two different embodiments A and B, separated from one another by the section line I-I. The collar 8 and the cone structure 10 as well as the contour 12 and the cone, partial cone or frustoconical shaped seat 13 have a fully circumferential configuration in a circumferential direction 14 in the embodiment A shown on the left side of FIG. 2. Only the contour 12 or the cone, partial cone or frustoconical shaped seat 13 can have an interruption in the area of a contact or joint zone 15, in which an upper shell 16 of the housing 2 is fastened to a lower shell 17 of the housing 2. As a result, efficient sealing of the corresponding inner panel 4 is achieved at the same time in the area of the collar 8 at the housing 2 in the circumferential direction 14. At the same time, a significant bracing of the housing 2 is made possible by the inner panel 4, which makes it possible, in particular, to remove external moments in the housing 2 due to the inner support at the inner panel 4.

(14) Contrary to this, FIG. 2 shows, in the second embodiment B shown on the right-hand side, a variant in which a plurality of collars 8, which may also be called collar segments 8, are arranged distributed in the circumferential direction 14. A plurality of cone segments 10 may correspondingly also be formed now. Analogously hereto, the contour 12 or the cone, partial cone or frustoconical shaped seat 13 may also be formed now by corresponding individual segments. However, an embodiment is shown in which the contour 12 and the cone, partial cone or frustoconical shaped seat 13 have a continuous configuration in the circumferential direction 14, aside from the interruption in the joint zone 15.

(15) In the left inner panel 4l shown on the left side of FIG. 1 as well as in the embodiments according to FIGS. 3 through 8, the housing 2 is equipped in the area of the inner panel 4, on the inner side 11 thereof, with a depression 18, with which the collar 8 meshes. The contour 12, which forms the cone, partial cone or frustoconical shaped seat 13 in profile, is located in this depression 18. Contrary to this, the housing 2 is provided in FIG. 1 in the case of the inner panel 4r shown on the right side, in the area of this inner panel 4, on its inner side 11, with an elevation 19, which projects into the interior of the housing 2. The contour 12, which forms the cone, partial cone or frustoconical shaped seat 13 in the profile, is formed at this elevation 19. FIG. 1 shows, purely as an example, a mixed mode of construction, in which the cone, partial cone or frustoconical shaped seat 13 is embodied by means of such a depression 18 for one inner panel 4l, while the cone, partial cone or frustoconical shaped seat 13 is embodied by means of such an elevation 19 for the other inner panel 4r. It is clear that all cone, partial cone or frustoconical shaped seats 13 are advantageously embodied by means of such a depression 18 or by means of such an elevation 19 in other embodiments, in which a plurality of inner panels 4 are positioned in the housing 2 by means of such a cone, partial cone or frustoconical shaped seat 13.

(16) Corresponding to FIGS. 3 through 8, the inner panel 4 may be axially prestressed at least at a mounting temperature. An axial prestress is indicated by an arrow and designated by 21 in FIGS. 3, 7 and 8. The axial prestress 21 brings about an axially prestressed contact of the cone structure 10 with the cone, partial cone or frustoconical shaped seat 13. The cone structure 10 and the cone, partial cone or frustoconical shaped seat 13 advantageously form a conical sliding fit 22. Such a conical sliding fit 22 can permit an axial as well as a radial relative motion between the inner panel 4 and the housing 2 and couple them with one another in a non-positive (non-fixed) manner and make possible in the process, furthermore, a flat contact between the cone structure 10 and the cone, partial cone or frustoconical shaped seat 13. An axial adjustment between the inner panel 4 and the housing 2 is indicated by an arrow and designated by 23 in FIG. 4. A radial adjustment between the housing 2 and the inner panel 4 is indicated by an arrow and designated by 24 in FIG. 4. The axial prestress 21 is advantageously generated via the exhaust pipe 5, which is supported at the housing 2, on the one hand, and at the inner panel 4, on the other hand. The axial prestress 21 may already be present at ambient temperature, namely, if the exhaust pipe 5 is mounted with such an axial prestress. Furthermore, the exhaust pipe 5 can also ensure the axial prestress 21 during the operation of the exhaust system, namely, when the exhaust pipe 5 expands to a greater extent in the axial direction than the housing 2 during the operation of the exhaust system, which is accompanied by a relative axial motion of the inner panel 4 relative to the housing 2.

(17) Furthermore, it is possible to prestress the housing 2 radially inwardly. Such a radial prestress is indicated by an arrow and is designated by 25 in FIGS. 3, 5 and 6. The radial prestress 25 also brings about a prestressed contact between the cone structure 10 and the cone, partial cone or frustoconical shaped seat 13.

(18) The exhaust pipe 5 and the inner panel 4 advantageously consist of a first material, which is, for example, a ferritic steel. The first material has a first coefficient of thermal expansion. The housing 2 is manufactured from another material, namely a second material, which may be, for example, an austenitic steel. The second material has a second coefficient of thermal expansion. The first coefficient of thermal expansion is lower than the second coefficient of thermal expansion. However, the temperature of the exhaust pipe 5 rises to a markedly greater extent during the operation of the exhaust system than that of the housing 2. As a consequence, the exhaust pipe 5 expands to a greater extent in the axial direction than does the housing 2. Contrary to this, the housing 2 expands to a greater extent in the radial direction than does the inner panel 4. These relative motions occurring during the operation are indicated in FIG. 4. The states for the initial situation, which occurs at ambient temperature, are indicated by broken line. By contrast, the states that become established at the operating temperature are shown by solid lines. As can be seen, the housing 2 expands outwardly relative to the inner panel 4. Further, the inner panel 4 is displaced axially relative to the housing 2 due to the expansion of the exhaust pipe 5. The conical sliding fit 22 can compensate these relative motions 23, 24 and permanently maintain a flat contact between the cone structure 10 and the cone, partial cone or frustoconical shaped seat 13.

(19) The axial direction is defined in this case by an axis 26 that extends at right angles to a plane 27, in which the respective inner panel 4 extends. In the example shown in FIG. 1, a central longitudinal axis 28 of the housing 2 extends parallel to the axis 26. The exhaust pipes 5 also extend essentially parallel to the axis 26 in this example.

(20) In order for the conical sliding fit 22 to be able to optimally absorb the relative motions 23, 24 occurring during the operation, a cone angle 29 indicated in FIG. 3, which the cone structure 10 and the cone, partial cone or frustoconical shaped seat 13 have in relation to the axial direction 26, is selected as a function of the coefficients of thermal expansion of the housing 2, inner panel 4 and exhaust pipe 5, namely, such that the radial expansion 24 of the housing 2 relative to the inner panel 4 is compensated by an axial expansion 23 of the exhaust pipe 5 relative to the housing 2 in the conical sliding fit 22. As a consequence, the flat contact between the cone structure 10 and the cone, partial cone or frustoconical shaped seat 13 continues to be present. According to FIG. 4, this means that when the temperature of the muffler 1 rises due to the operation of the exhaust system, a radial expansion 24 of the housing 2, which would lead to the housing 2 being lifted off from the collar 8 in case of the usual mode of construction, will take place, on the one hand, relative to the inner panel 4. However, an axial expansion 23 of the exhaust pipe 5 takes place at the same time, and this expansion generates a corresponding axial adjustment 23 of the inner panel 4 relative to the housing 2. Based on this axial adjustment 23, the cone structure 10 remains in contact with the cone, partial cone or frustoconical shaped seat 13, so that the conical sliding fit 22 can compensate said relative motions 23, 24 caused by thermal effects and the contact is maintained between the cone structure 10 and the cone, partial cone or frustoconical shaped seat 13.

(21) According to FIGS. 5 and 6, such a muffler 1 can be manufactured according to a first method such that the inner panel 4 is first inserted into the lower shell 17 of the housing 2, the upper shell 16 is then placed on the lower shell 17 and a radial prestress is generated in the process, which brings about an elastic bulging in the preferential direction of the inner panel 4. Such bulging 30 of the inner panel 4 is shown in FIG. 6 in an exaggerated manner. The upper shell 16 is then fastened to the lower shell 17, which is carried out with the inner panel 4 bulged, so that the housing 2 is subsequently mounted in the radially inwardly prestressed state. The radial prestress 25 is correspondingly present in the mounted state at the mounting temperature.

(22) A second manufacturing method, which may be carried out as an alternative to the above-described manufacturing method, is explained in more detail with reference to FIGS. 7 and 8. It is, however, also possible, in principle, to embody the two manufacturing methods cumulatively.

(23) The inner panel 4 with the exhaust pipe 5 fastened to it is first inserted into the lower shell 17 of the housing 2. The upper shell 16 is then placed on the lower shell 17. The exhaust pipe 5 is then pushed inwardly such that the inner panel 4 will bulge elastically in the preferential direction. A corresponding bulging is designated by 30 in FIG. 8 and is shown in an exaggerated form in this case as well. The exhaust pipe 5 is then fastened to the housing 2, while the inner panel 4 is bulged elastically in the preferential direction. The exhaust pipe 5 is thus subsequently mounted in the axially inwardly prestressed state. The corresponding axial prestress 21 is indicated by arrows in FIGS. 7 and 8.

(24) If the above-described two methods are cumulated, the upper shell 16 is placed on the lower shell 17 to generate the radial prestress 25 after inserting the inner panel 4 with the exhaust pipe 5 fastened to it into the lower shell 17. The upper shell 16 is subsequently fastened to the lower shell 17 in order to guarantee or preserve the radial prestress 25 between the housing 2 and the inner panel 4. The exhaust pipe 5 now remains adjustable relative to the housing 2. The exhaust pipe 5 is then pushed inwardly in order to also generate the axial prestress 21. With the axial prestress 21 applied, the exhaust pipe 5 is then fastened to the housing 2 in order also to guarantee or preserve the axial prestress 21 between the inner panel 4 and the housing 2.

(25) 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.