GB2278413A

GB2278413A - Segmented housing for exhaust damper

Info

Publication number: GB2278413A
Application number: GB9409307A
Authority: GB
Inventors: Wieland Holzhausen
Original assignee: IWK Regler und Kompensatoren GmbH
Current assignee: Metra Energiemesstechnik GmbH
Priority date: 1993-05-25
Filing date: 1994-05-10
Publication date: 1994-11-30
Anticipated expiration: 2014-05-10
Also published as: GB2278413B; FR2705727A1; GB9409307D0; ITMI941053A1; ITMI941053A0; FR2705727B3; DE4317333A1; DE4317333C2; IT1269831B

Description

APPARATUS FOR DAMPING VIBRATIONS IN EXHAUST LINES OF MOTOR VEHICLES

2278413 The invention relates to an apparatus for damping or absorbing vibrations particularly in exhaust lines of motor vehicles with at least one pressed metal wire damping or absorbing cushion or pad located in a casing.

Apparatuses of this type for the damping of vibrations, particularly in exhaust lines of motor vehicles with pressed metal wire damping cushions located in casings are known in connection with decoupling elements from DE-A-33 21 382 or EP-A-208 128 in the form of the casing containing the damping cushions thereof.

Abutments provided on the two end faces of the particular apparatus are connected to the same connection end of the decoupling element, whereas to the other end is connected an abutment, which engages approximately centrally between two axially succeeding cushions or in a radial recess of a single cushion.

It has been found that in the known apparatuses and decoupling elements the damping cushions only function with a very small part of their volume, namely directly where the forces are introduced. Most of the volume remains undisturbed. Thus, the cushions are overdimensioned and this was in particular necessary due to the central engagement of the abutment connected to one connection end. Due to the fact that the casing cannot be completely closed, the cushions are also exposed to corrosive influences, either within the flow path to the hot exhaust gases or outside the same to dirt, wet and salt. It has also been found that in particular that cushion part which does not or only works little under normal operating conditions hardens or encrusts, so that the dynamic characteristics present in the new state change in a disadvantageous manner. As the hitherto known apparatuses are constructed in integrated mariner with the decoupling elements, they must be designed from the outset specifically for the corresponding element. Therefore they 2 cannot be provided in modular manner for different decoupling elements and only subsequently adapted.

The damping cushions contained in the casings can only be handled with difficulty in automatic manner, because they hook together, so that limits are placed on the degree of mation. Wire cushions constitute a "brittle" product and difficult to install in automated manner, particularly if is a stretched strand and not a (circular) shaped cushion.

easily auto- are there As a result of the indicated overdimensioning the hitherto known damping or absorbing apparatuses and decoupling elements took up a large amount of space, either in the radial, or in the axial direction.

The problem of the invention is therefore to avoid the aforementioned disadvantages.

In the case of an apparatus of the aforementioned type, this problem is solved by the invention in that juxtaposed, outer, frontal casing wall portions are movable relative to one another as abutments for the damping cushions.

Therefore the casing halves and in particular the casing wall portions are not directly in contact. Instead between the casing halves and wall portions there are gaps and spaces. Juxtaposed, outer, frontal casing wall portions located on one side of the damping cushion are consequently movable relative to one another and in particular in the direction of the perpen dicular thereof.

Due to the fact that both axial abutments for the damping cushions can be displaced towards the outside, i.e. into the casing walls for said cushions and abutments acting against one another are able to absorb both pulling movements on the two connection ends of the decoupling element and also pressing move- - 3 ments against one another, in that on each end face of the cushion, in particular circumferentially juxtaposed wall portions alternately connected to one or other connection end of the decoupling element and therefore axially movable relative to one another, it has proved possible to avoid the centrally positioned abutments according to the prior art. This has made it possible to reduce the cushion volume and substantially by that part which has hitherto been inactive. For example, compared with designs having two cushions located on either side of the central abutment, one of these has been obviated. In addition, the apparatus according to the invention forms a dynamically more active component. Apart from material savings with respect to the relatively expensive cushion material, the design according to the invention has the advantage of being very compact, particularly with respect to the overall length of the decoupling elements as well, into which the apparatus according to the invention is inserted. This is important, because not very much space is available at the particularly effective installation points for decoupling elements. The degree of utilization of the apparatus according to the invention is greater than in the prior art, whilst the constructional effort and expenditure are less. As the damping cushions can become entangled and therefore cannot be separated, e.g. by means of a vibrating conveyor. limits are placed on the automatic manufacture of the decoupling elements and the prior art. However, the apparatuses according to the invention can be prefabricated as single, uncomplicated units (cassettes) and as such can be automatically conveyed on and processed. The cushions can be supplied in per se known manner in strand form and for use in the casing halves can be cut to length at the latter and the cut-to-length portions can be automatically used, so that the problem of individualizing or separating cushions does not occur.

Whilst it is fundamentally possible to provide rigidly inter connected wall portions on both end faces of the casing so as to face one another, although this leads to gravitational forces 4 - and the movement is absorbed by means of shearing actions of the cushion material, according to preferred developments one wall portion is faced by another wall portion movable relative thereto on the other end face of the casing and in particular the rigidly interconnected wall portions located on both end faces of the casing overlap one another.

Fundamentally there is only one axially directed cushion layer. However, in special constructions there can be several cushion layers in the axial direction without having abutments between them. The apparatus according to the invention can be constructed as an individual casing to be arranged on the circumference of the decoupling element, but can also have a circular construction. In the latter case the damping cushions can also be cir cular or part-circular, either their radial end faces engage on one another or engage on specifically provided abutments. In the latter case and in the case of a separate casing with damp ing cushio ns provided around the circumference of the exhaust lines, the damping cushions are arranged in radial planes, in which there are preferred angular movements between the pipe ends.

Whereas fundamentally the wall portions movable relative to one another have the same size, according to a preferred development the frontal wall portions movable relative to one another can be given a different size and in particular the total surface of a first group of wall portions to be interconnected can differ from the total surface of the group of the wall portions movable relative thereto, but also rigidly interconnected. The group of the wall portions with the larger total surface is that which my have to absorb static initial loads, such as the weight of the exhaust system.

With respect to the angular movements of the pipe ends of the decoupling elements, which are provided with the damping apparatuses according to the invention and therefore having a good angular articulated nature, according to a preferred development the wall portions are curved and in particular convex.

Fundamentally the cushions can be inserted in tensionless manner in the casing of the apparatus according to the invention. However, according to a preferred development, the damping cushions are pretensioned in the casings, so that even with end wall areas moving apart under certain movements there is only a small gap between them and adjacent cushion outsides and instead the cushions follow the movement of the wall portions.

According to a preferred development of the apparatus according to the invention the damping cushion is constructed in the man ner described hereinafter. The damping cushion comprises a strand portion separated from an endless strand and which is consequently at a finite angle to said extension direction or its edges and is curved in the desired shape, e.g. a circular ring shape. Separation or cutting can take place by fusion cutting, laser cutting, high pressure cutting by means of liquid or the like. According to a preferred development the cushions rest flat on one another so as to form a closed ring on bending the strand part. The flatly superimposed cutting or separating surfaces can then either be unconnected, if the cushions are held in shape by the surrounding cassette or casing, or they can be appropriately interconnected, e.g. by welding or bonding.

Furthermore, the ends of the strand part can be so compressed that they overlap on bending to a circular part and in particular the ends at remote end faces of the strand part are compressed towards different lateral faces thereof. Joining can take place by resistance welding, by sheet metal supports adapted to the ends, by bonding, needling or sewing.

The endless strand and therefore the cushion can be so constructed in preferred manner that it comprises several, juxtaposed -- 6 layers and either a wide hose is corrugated at right angles to its extension direction and the individual layers are super imposed and compressed, or several narrow hose parts are placed on one another and compressed. According to a further develop ment for finished cushions, e. g. a circular cushion, it can be provided that the layers are concentric to one another or for the individual layers to be axially juxtaposed, the individual strands or layers being additionally secured by needling.

The invention offers for the first time a practical use for a compressed gauze wire or random laid layer strand and avoids through the use of the separated strand parts directly in a simple casing or cassette, which is as such further handlable, e.g. for transportation and processing, as well as ultimately in the decoupling element from connecting pieces and bellows part and optionally casing parts covering the latter or support parts extending through the bellows, the further extending, complicated treatment of individual wire fabric cushions which, as stated hereinbefore, cannot be automated, because the cushions can easily hook together and are therefore not separatable in the conventional manner. However, separation or individualization is possible in the damping apparatus according to the invention, as a result of the closed casing surrounding the same. In addition, they can be used with different decoupling elements and optionally by increasing the pretension in the abovedescribed manner can be adapted to different uses and different decoupling elements.

According to further developments of the invention the damping cushions are covered by facing, full wall surfaces, from which front wall portions extend at an angle with a relative circumferential spacing and in each case engage in one another and that at an angle to the front wall portions extend extensions and in particular the wall parts of the casing have reinforcing seams or fins.

7 The cassette is at the same.time a tool for shaping the wire cushion, at least with respect to its bending to a ring and ultimately houses the end product, whose handling causes no problems.

Strand cushions bent to a ring have at the junction of the ends a "fault point". This deficiency is removed in that it is bridged by internal reinforcements and/or, as indicated hereinbefore, the cassette closely embraces the cushion on all sides and/or the operating loads are distributed over a maximum number of abutments.

Further advantages and features of the invention can be gathered from the claims, the following description of non-limitative embodiments of the invention and the attached drawings, wherein show:

Fig. 1 A side view of a preferred vibration damping apparatus according to the invention.

Fig. 2a A section corresponding to II-II of fig. 1 with the cassette not closed. Fig. 2b A section corresponding to II-II of fig. 1 with the cassette closed. Fig. 3 A view corresponding to fig. 1 for a different construction of the apparatus according to the invention. Fig. 4 A section corresponding to fig. 2a through another embodiment of the apparatus according to the inven tion. Fig. 5 The installation of the apparatus according to the invention in a decoupling element shown diagraminatically.

Fig. 6 A further construction of the apparatus according to the invention in a section similar to that of fig. 2a. Fig. 7 Diagrammatic representations of constructions of the casing parts for shaping the cassettes after installation for setting a clearly defined pretension. Fig. 8 A damping cushion with flat engaging end faces bent circular from a strand portion according to fig. 9. Fig. 9 The side view of a strand with section lines diverging from an angle of 900 with respect to the extension line for producing a circular cushion according to fig. 8. Fig. 10 A circular cushion with radial overlapping, pressed together ends.

Fig. Ila A circular cushion with in end view overlapping, pressed ends corresponding to the arrow XIa of fig. Ilb.

Fig. llb A plan view of the cushion of fig. Ila corresponding to the arrow XIb of fig. Ila.

The vibration damping or absorbing apparatus according to the invention, particularly for use in exhaust lines of motor vehicles, has a casing 2, which is preferably circular and contains damping or absorbing cushions or pads 3 and namely in the case of a circular shape either a circular cushion or several sector-shaped cushions, which can be in engagement with one another by their radially directed end faces or can engage on abutments connected to the casing. In the axial direction several damping cushions 3 can be juxtaposed and between the same there are no rigid abutments connected to the casing.

The casing 2 is constructed as a cassette and comprises two casing parts 4, 6. One of the casing parts 4 has an outer circumferential wall 7, from which extend inwards front wall portions 8, 9, between which are in each case formed recesses 11, 12. The front wall portions 9, 8, which enclose between them the damping cushion or cushions 3, are preferably circumferentially displaced and either on the wall portion 8 on one end face precisely symmetrically faces a recess 12 on the other end face (fig. 3) or has a slight angular displacement V (fig. 1). As a result of the displacement, to which corresponds a corresponding displacement V' of the wall portion 9 adjacent to the recess 12, there is a partial coverage (corresponding to V) of the wall portions 8, 9 formed on opposite end faces.

Between the edges of the casing parts 4, 6 there are finite gaps or spaces permitting a relative movement in the unloaded state.

Covering areas U1, U2 are achieved in the case of the symmetrical construction of fig. 3 in the outer casing part 4 in that the wall parts 8, 9 of part 4 are larger than the wall parts of the inner casing part 6.

The inner casing part 6 has an inner circumferential wall 16 from which extend outwards wall portions 17, 18 into the recesses 11, 12 between the wall portions 8, 9 of the outer casing part 6 and once again form between them corresponding recesses 19, 21.

The damping cushion or cushions on one of their end faces, considered circumferentially, alternately engage on wall portions 8, 17 of the casing parts 4, 6 and on the other circumferential side, once again considered circumferentially, alter nately engage on the wall portions 9, 18 of the casing parts 4, 6.

The damping cushions 3 are inserted in the casing 2 with a pretension, by being placed in the casing parts 4, 6 accompanied by compression.

The casing parts 4, 6 are firmly connected to different pipe ends of a decoupling element connected by a gas-tight, flexible pipe part, such as a bellows, or are constructed thereon (further details hereinafter).

If the pipe or connection ends move relative to one another, then this movement is transferred to the two casing parts 4, 6. In the case of an axial movement corresponding to AI, A2 in fig. 2b, the wall areas 8, 17 are moved against one another (whereas the wall areas 9, 18 move apart) and tend to further compress the damping cushion 3 and once again due to its damping characteristics has a vibration damping effect on the movement of the wall portions 8, 9 and therefore ultimately the pipe ends.

In the construction according to fig. 4 the casing parts 4, 6 are in each case in two parts, the wall portions 8 being constructed in one piece with the circumferential wall 7 and the latter has an attachment 22. The wall portions 9 are constructed on an angular attachment 23, which is connectable to the attachment 22 such as by welding and it is possible to use all types of welding such as fusion, resistance or laser welding. However, a mechanical connection method is also possible, such as pressing, beading, pressure joining, etc.

Whereas in the construction of figs. I to 2b the assembly of the cassettes must take place radially and at least the outer casing part 4 must be in two pieces, e.g. in the form of two halfshells, with the construction of fig. 4 there can be an axial assembly in the direction of the axis A. Initially, e.g. the parts 7, 8, 22 and 18 are telescoped with the attachment 26 in such a way that the wall portions 18 engage between the wall portions 8. Subsequently, from the left the damping cushion 3 - 11 is shoved axially, and 16, side of the gaps desired as well welding up against the wall portions 8, 18. Then, once again either simultaneously or successively the parts 9, 23 17 with the attachment 24 are moved against the left end the damping cushion, the wall portions 17 engaging in between the wall portions 9 and vice versa. The pressure is exerted and subsequently the parts 22 and 23, as 24 and 26, are Joined in the described manner by or one of the other methods defined.

Thus, the parts 22 to 26 initially serve to fix the part 7, 8, 22 to the part 9, 23 or the part 16, 17, 24 to the part 18, 26 with the cushions 3 pretensioned, but also for fixing the resulting apparatus according to the invention to the connecting piece of the corresponding decoupling element.

Fig. 5 highly diagrammatically shows a decoupling element with an apparatus according to fig. 4. The decoupling element has pipe ends 31, 32, which are connected in per se known manner by a gas-tight, flexible line element 33, such as a metal bellows. The pipe end 31 is constructed on a circular casing 34 engaging over the metal bellows 33. At the end of the casing 34, the latter is firmly connected to the attachments 23, 23 (such as by welding), whilst it is not connected to the casing part 6. The latter is firmly connected with its attachments 24, 26 (such as by welding) to the pipe end 32 (in each case at the points indicated by crosses).

Fig. 6 shows a similar construction to fig. 4. However, in this case there are no radial end wall parts 8, 9, 17, 18 connected in one piece to the circumferential walls 7, 16 of the casing parts 4, 6 and instead they are separately constructed with angular attachments 41, 42, 43, 44 by means of which the end wall portions 8, 9, 17, 18 are connected to the circular or cylinder jacketshaped circumferential wall parts 7, 16.

- 12 Assembly can take place in much the same way as in fig. 4. The fitting in the decoupling element can take place as described relative to fig. 5.

Fig. 7 shows reinforcing fins 51, 52, 53, 54 on the casing parts 4, 6. If necessary, following the assembly of the cassette-like casing, subsequently the pretension can be matched in the.desired manner by means of said fins 51 to 54, e.g. adapted to different uses of the prefabricated apparatuses according to the invention.

The inventive construction of a vibration damping apparatus in the form of the above-described cassette makes it possible for the first time to use in simple, economic manner per se known strand material formed from pressed metal wire as damping cushions in such an apparatus. For this purpose, from a corresponding strand material 101 a portion 102 can be cut under a finite angle to the extension direction R of the strand material and bent in accordance with fig. 8. In the case of a vertical cut to the extension direction, the areas of cut 103, 104 are either not parallel, or the strand material must be pressed more strongly radially inwards than radially outwards. As this is not desired, according to the preferred embodiment of figs. 8 and 9, the strand material is cut off with areas of cut 103, 104 under an angle not equal to 90 to the extension direction R of said strand material 101 and namely under an angle such that on bending the strand portion 102 to for a closed ring 105 (fig. 8), the two areas of cut 103, 104 are parallel to one another. In the case of such bending, as a function of the radius of the ring 105 produced, the radially inner areas are necessarily compressed somewhat, whereas the radially outer areas are necessarily stretched somewhat. It is therefore not possible to give a precise cutting angle. As a function of the radius or diameter of the circular cushion 105 to be obtained, it is easily possible to obtain the cutting direction of the areas of-cut 103, - 13 104 by means of a few tests; The arc B1 and B2 indicate how the strands of fig. 9 are bent to the circular cushion 105. The areas of cut 103, 104 can be appropriately interconnected, e.g. by bonding or welding.

Fig. 10 shows a further preferred development in which there is an overlapping of the ends 111, 112 of a strand part 102. As shown in fig. 10, the ends are pressed for this purpose radially, so that they overlap in the radial viewing direction.

Alternatively pressing can take place from the end faces 113, 114 of the ring part 105, so that in the viewing direction there is an overlap area 116 perpendicular to the end faces 113, 114 (or parallel to their perpendiculars), as indicated in figs. 11a and 11b.

Here again the joining of the ends can take place in different ways, namely by resistance welding, bonding, needling or sewing the overlapping ends by means of metal wire using clips. The ends can also be provided with suitable sheet metal supports or can be enclosed by the latter.

The separation of the portions 102 at the cut lines 103, 104 of the strand 101 can take place by cutting off, shearing, fusion cutting, laser cutting or high pressure liquid cutting.

The strand 101 is preferably constructed in multilayer form and a wide, pressed flat hose is multiply corrugated transversely to its longitudinal direction and the corrugations are pressed against one another. It can also be in multipart form, in that several weak hoses are corrugated, engaged and compressed. Optionally the individual strands or layers can be additionally connected by needling.

Claims

1. Apparatus for damping vibrations, particularly in exhaust lines in motor vehicles, with at least one pressed metal wire damping cushion located in a casing, characterized in that juxtaposed, outer, front casing wall portions (8, 9, 17, 18) are movable relative to one another as abutments for the damping cushions (3).

2. Apparatus according to claim 1, characterized in that a wall portion (8, 18) is faced by a wall portion (17, 9), movable relative thereto, on the other end face of the casing (2).

3. Apparatus according to claim 1 or 2, characterized in that the rigidly interconnected wall portions (8, 9) arranged on both end faces of the casing (2) overlap one another.

4. Apparatus according to any one of the preceding claims, characterized in that rigidly interconnected wall portions arranged on both end faces of the casing face one another.

5. Apparatus according to any one of the preceding claims, characterized in that there is only one cushion layer in the axial direction.

6. Apparatus according to any one of the preceding claims, characterized in that there are several cushion layers in the axial direction without abutments located between them.

7. Apparatus according to any one of the preceding claims, characterized in that several cushions are juxtaposed, particularly circumferentially.

8. Apparatus according to any one of the preceding claims, characterized in that the front wall portions (8, 9, 17, 18), movable relative to one another, have different sizes.

- is

9. Apparatus according to claim 8, characterized in that the total surface of a first group of in each case connected wall portions (8, 9) is different to the total surface of the also rigidly interconnected wall portions (17, 18) movable relative thereto.

10. Apparatus according to any one of the preceding claims, characterized in that the wall portions (8, 9, 17, 18) are curved.

11. Apparatus according to claim 10, characterized in that the wall portions (8, 9, 17, 18) are convex.

12. Apparatus according to any one of the preceding claims, characterized in that the damping cushions (3) are pretensioned in the casings (2).

13. Apparatus according to any one of the preceding claims, characterized in that the damping cushions (3) are covered by facing, full wall surfaces (7, 16), whereof in each case interengaging, front wall portions (8, 9, 17, 18) extend at an angle to one another with a relative circumferential spacing.

14. Apparatus according to any one of the preceding claims, characterized in that extensions (22, 23, 24, 26, 41, 42, 43, 44) extend angularly to the front wall portions (8, 9, 17, 18).

15. Apparatus according to any one of the preceding claims, characterized in that the wall parts (7, 8, 9, 16, 17, 18) of the casing (2) have fins (51, 52, 53, 54).

16. Damping cushion formed from pressed metal wire, with paraIlel longitudinal edges, particularly Eor an apparatus according to any one of the claims 1 to 15, characterized in that the cushion (105) is formed by separating a strand portion (102) from an endless strand (101) under a finite angle to the longitudinal edges of the endless strand (101).

17. Cushion according to claim 16, characterized in that the strand portion (102) is formed by fusion separation from the endless strand (101).

18. Cushion according to claim 16, characterized in that the strand portion (102) is separated by laser cutting from the endless strand (101).

19. Cushion according to claim 16, characterized in that the strand portion (102) is separated by high pressure liquid cutting from the endless strand (101).

20. Cushion according to any one of the preceding claims, characterized in that the cushions engage flat on one another on bending the strand portion (102) to a closed ring.

21. Cushion according to any one of the claims 16 to 20, characterized in that the ends of the strand portion (102) are compressed in such a way that on bending to a ring part they overlap.

22. Cushion according to claim 21, characterized in that the ends on remote end faces of the strand portion (102) are com pressed to different lateral faces thereof.

23. Cushion according to any one of the claims 16 to 22, characterized in that the ends of the strand part (102) are joined together by resistance welding.

24. Cushion according to any one of the claims 16 to 22, characterized in that the ends of the strand part (102) are joined together by an adapted sheet metal support.

17 -

25. Cushion according to any one of the claims 16 to 22, characterized in that the ends of the strand part (102) are bonded together.

26. Cushion according to any one of the claims 16 to 22, characterized in that the ends of the strand part (102) are needled or sewn.

27. Cushion according to any one of the claims 16 to 26, characterized in that it comprises several, juxtaposed layers.

28. Cushion according to claim 27, characterized in that layers are arranged concentrically to one another.

29. Cushion according to claim 27, characterized in that individual layers are axially juxtaposed.

30. Apparatus for damping vibrations according to any one of the claims 1 to 15, characterized in that the damping cushion (3, 105) is constructed according to any one of the claims 17 to 29.