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Title:
DECOUPLING JOINT FOR EXHAUST PIPINGS OF ENDOTHERMIC ENGINES
Document Type and Number:
WIPO Patent Application WO/2011/148252
Kind Code:
A1
Abstract:
A decoupling joint (1) insertable in series along an exhaust piping of an endothermic engine, including: a flexible metal sleeve (2), which is fluid-tight and bellows-shaped, in turn including a plurality of first annular corrugations (8) and a pair of cylindrical opposite terminal ends (9,10) free from corrugations; a pair of opposite heads (6,7) each coaxially and fluid-tightly secured to a respective cylindrical end of the bellows (2); and at least one damping element (3) made in the form of a cylindrical sleeve formed by a mesh pad (4) made of metal wire (5) fitted on the bellows-shaped sleeve (2); in which respective ends (12,13) of the damping element (3) are axially locked with respect to bellows-shaped sleeve (2), each end directly on a respective annular flange (14) which is integrally obtained in one piece with a respective head (6,7) and radially on the exterior with respect to the bellows- shaped sleeve (2), crimped straddling the flanges by way of respective U-folded rings (15) on respective peripheral edges (16) of the flanges (14).

Inventors:
DEBERNARDI GIANFRANCO (IT)
Application Number:
PCT/IB2011/001121
Publication Date:
December 01, 2011
Filing Date:
May 25, 2011
Export Citation:
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Assignee:
FLEXIDER S R L (IT)
DEBERNARDI GIANFRANCO (IT)
International Classes:
F16L27/111; F01N13/18; F16L51/02
Foreign References:
EP0989289A12000-03-29
EP1054140A12000-11-22
DE202008006236U12008-08-07
EP0657683A21995-06-14
US6220023B12001-04-24
Attorney, Agent or Firm:
JORIO, Paolo et al. (Via Viotti 9, Torino, IT)
Download PDF:
Claims:
CLAIMS

1. A decoupling joint (1) insertable in series along an exhaust piping of an endothermic engine, comprising: a flexible metal sleeve (2) which is fluid-tight and bellows- shaped, in turn comprising a plurality of first annular corrugations (8) and a pair of opposite cylindrical terminal ends (9,10), free from corrugations; a pair of opposite heads (6,7), each coaxially and fluid-tightly secured to a respective cylindrical end (9,10) of the sleeve (2) and intended in use to be connected to the exhaust piping; and at least one damping element (3) made in the form of a cylindrical sleeve formed by a mesh pad (4) made of metal wire (5) fitted on the bellow-shaped sleeve (2) in forced contact with at least the first annular corrugations (8) thereof;

characterized in that opposite ends (12,13) of the damping element (3) are axially locked with respect to the bellows-shaped sleeve (2), each end directly on a respective annular flange (14) , which is integrally obtained in one piece with a respective head (6,7); said ends being locked on said flanges radially on the exterior of the head itself with respect to the bellows-shaped sleeve (2); said ends being peripherally crimped to the flanges (14) straddling thereof by means of respective rings (15) mounted so as to be rammed U- folded on respective radially outer edges (16) of the flanges (14) so that each ring sandwiches a U-folded portion (17) of the respective end (12,13) of the damping element, against opposite faces of the respective flange (14) .

2. A joint (1) according to claim 1, characterized in that said damping element (3) made in the form of a cylindrical sleeve formed by a mesh pad (4) made of metal wire (5) has truncated-conical, front fitting portions (18,19) arranged between the respective U-folded portions (17) of its ends (12,13) seamed onto said flanges (14) and the rest of the sleeve (3) in contact with said first corrugations (8).

3. A joint according to claim 2, characterized in that said U-folded portions (17) of the ends (12,13) of the damping element (3) seamed onto the flanges (14) keep said truncated- conical, front fitting portions (18,19) in forced contact against second corrugations (11) of the beHows-shaped sleeve (2) which are arranged adjacent to said cylindrical terminal ends (9,10) free from corrugations and having a progressively decreasing height with respect to that of said first corrugations (8) as they approach the cylindrical terminal ends (9,10) free from corrugations.

4. A joint according to one of the preceding claims, characterized in that said sleeve-shaped damping element (3) is fitted with radial interference on respective crests of at least part of said first corrugations (8) .

5. A joint according to one of the preceding claims, characterized in that each said head (6,7) is formed by a first annular element (20) , radially arranged on the interior of said beHows-shaped sleeve (2) and by a second annular element (21) radially arranged on the exterior with respect to said bellows-shaped sleeve and coaxial with the first annular element (20); said cylindrical ends (9,10) free from corrugations of the bellows-shaped sleeve being each radially sandwiched between the first and second annular elements (20,21) of each head (6,7).

6. A joint according to claim 5, characterized in that said annular flange (14) obtained in one piece with each head consists of a terminal edge of said second element (21) of the respective head (6,7), facing towards the corrugations (8,11) of said bellows-shaped sleeve (2) and which is L-folded radially outwards.

7. A joint according to claim 5 or 6, characterized in that said first annular element (20) of each head axially extends so as to protrude within a segment of the bellows- shaped sleeve (2) adjacent thereto, provided with at least some corrugations (11) .

8. A joint according to claim 7, characterized in that it further comprises a flow-guide tubular element or liner (22), concentrically arranged inside the flexible bellows-shaped sleeve (2) and made of a crimped metal tape, helically wound so as to form a tube, which is arranged so as to be radially spaced from the beHows-shaped sleeve (2) and integrally fitted, by its opposite ends, on respective segments (23) of said first annular elements (20) of the heads (6,7) which axially extend so as to protrude within the bellows-shaped sleeve (2) .

Description:
"DECOUPLING JOINT FOR EXHAUST PIPINGS OF ENDOTHERHIC ENGINES"

TECHNICAL FIELD

The present invention relates to a decoupling joint for exhaust pipings of endothermic engines having highly efficiency and that can be made in a simple and economical way.

BACKGROUND ART

It is known that the exhaust systems of thermal combustion engines of modern vehicles are provided with one or more flexible sleeves, described here and in the following with the general term of "decoupling joints", located between the engine and the final part of exhaust piping, having the task of compensating for misalignments /positioning errors of different segments of the exhaust piping and/or reduce/eliminate vibration from the engine to the exhaust system in general and to certain delicate components thereof, particularly the catalytic purifiers (the so-called "catalytic mufflers" ) .

As shown, for example in EP 0657683 , said decoupling joints are formed by a bellows-shaped and fluid-tight flexible metal sleeve, being provided in turn with one or more reinforcing non fluid-tight flexible metal sleeves, and damping elements interposed between the bellows and at least one of the reinforcement sleeves; they are arranged in use, at least along the length of the piping between the engine and the catalytic purifier, in an area, therefore, relatively inaccessible and in which the available space is limited.

Known decoupling joints, although with relatively good efficiency, particularly the one according to EP 0657683 , have the disadvantage of requiring numerous component elements, increasing production cost, bulk and weight. A simplified joint is known from US6220023B1, where the beHows-shaped sleeve is directly covered by a single sleeve made of woven wire mesh tightly bound against the corrugations of the bellows. In this type of solution, however, the wire mesh sleeve, to be effective, must be locked directly onto the annular heads that delimit the joint ends and therefore presents the opposite ends sandwiched, along with opposite cylindrical ends free from the corrugations of the bellows, between two annular elements, one being radially internal and one radially external to the bellows. This type of assembly, although relatively effective, entails that, in use, the woven wire mesh sleeve ends become involved with the welding bead necessary for connecting the heads to the piping segments to be joined, thus making the welding procedure extremely difficult, leading to unreliable welding beads.

DISCLOSURE OF INVENTION

The aim of the invention therefore is to resolve these problems by way of a decoupling joint presenting reduced dimensions and weight along with a low manufacturing cost and high efficiency in action, both in terms of duration, damping of vibrations and noise, and which does not create any problem during the welding step of the heads. According to the invention, a decoupling joint for exhaust piping of thermal engines is thus provided, as defined in claim 1.

In particular, the decoupling joint comprising: a flexible metal sleeve, which is fluid-tight and bellows-shaped, and in turn comprising a plurality of first annular corrugations and a pair of opposite cylindrical terminal ends, free from corrugations, a pair of opposite heads, each coaxial and fluid-tightly secured to a respective cylindrical end of the sleeve and intended in use to be connected to the exhaust piping, and at least one damping element made in the form of a cylindrical sleeve formed by a mesh pad made of wire mesh fitted on the beHows-shaped sleeve in forced contact with at least the first annular corrugations thereof. According to the main feature of the invention, opposite ends of the damping element are axially locked with respect to the bellows-shaped sleeve, each end directly upon a respective annular flange, which is integrally obtained in one piece with a respective head; said ends being locked on said flanges radially on the exterior of the head itself with respect to the bellows-shaped sleeve; said ends being peripherally crimped to the flanges straddling thereof by means of respective rings mounted so as to be rammed U-folded on respective radially outer edges of the flanges, so that each ring sandwiches a U-folded portion of the respective end of the damping element, against opposite faces of the respective flange .

Each head is formed by a first annular element, radially arranged on the interior with respect to said bellows-shaped sleeve and by a second annular element radially arranged on the exterior with respect to said bellows-shaped sleeve and coaxial with the first annular element. The cylindrical ends free from corrugations of the bellows-shaped sleeve being each radially sandwiched between the first and second annular elements of each head; and the annular flange obtained in one piece with each head consisting of a terminal edge of said second element of the respective head, facing towards the corrugations of said bellows-shaped sleeve and which is L- folded radially outwards.

Optionally, the joint may eventually comprise also a flow- guide tubular element or liner, concentrically arranged inside the flexible beHows-shaped sleeve and made of a crimped metal tape, helically wound so as to form a tube, which is arranged so as to be radially spaced from the bellows-shaped sleeve and integrally fitted, by its opposite ends, on respective segments of the second annular elements of the heads which axially extend so as to protrude within the bellows-shaped sleeve .

In this way, a decoupling joint of extremely simple and lightweight structure is achieved, whose essential parts are formed only by the heads and by two coupled elements comprising the bellows and the meshed metal wire sleeve.

Surprisingly, however, such joint has proven to be highly efficient and reliable in damping vibration and noise, as the damping element in the form of a sleeve formed by a pad made of meshed metal wire, which is fitted axially locked onto the flanges made in one piece with the heads, radially on the exterior of the beHows-shaped sleeve and fitted with interference onto the exterior of the bellows, by subjecting it to an enlargement process to its elastic limit during assembly, tightens in use substantially all corrugation crests of the bellows, not only those of the above mentioned first corrugations, but also those of second corrugations of the bellows-shaped sleeve placed adjacent to the terminal ends thereof and of gradually decreasing height with respect to that of the first corrugations as they approach said terminal cylindrical ends free from corrugations of the bellows, therefore creating such a friction as to entail a positive change of the dynamic characteristics of the bellows, which is no longer subject to risks of resonance at operation frequencies, especially near the heads where usually the majority of cracks during use occurs, while maintaining a high flexibility in the joint as a whole.

In addition, such external pad made of meshed metal wire can be made of sufficiently tight meshes to serve as an effective external protection element of the bellows and no longer requires, due to the original mounting system by plastic deformation on the head flanges, a further external element, such as a metal wire sock.

But, above all, the area of the heads destined to receive welding is completely free from the sleeve formed by the mesh pad made of metal wire or any other foreign element, thus ensuring to obtain easy, quick and highly reliable welding beads . BRIEF DESCRIPTION OF THE DRAWINGS

Additional features and advantages of the invention will appear clear from the following description of a non-limiting embodiment thereof, made only by way of example, with reference to the figures of the attached drawing, in which: - Figure 1 shows a longitudinal view in elevation, partly in radial section of a decoupling joint made according to the invention, and

- Figure 2 shows, on an enlarged scale, a detail of the decoupling joint of Figure 1.

BEST MODE FOR CARRYING OUT THE INVENTION

With reference to Figures 1 and 2, it is indicated as a whole with 1 a decoupling joint (or decoupler joint) for exhaust pipings of thermal engines (known and not shown for simplicity) , insertable in use, in a known way, in series along an exhaust piping of an endothermic engine, also known and not shown for simplicity.

The decoupler joint 1 is symmetrical with respect to a longitudinal axis A, and comprises, without limitation in the case illustrated (Figure 1), a flexible metal sleeve 2, which is fluid-tight and bellows-shaped; a damping element 3 made of a flexible cylindrical sleeve formed by a mesh pad 4 made of metal wire 5 (wire mesh) , placed on the exterior coaxially with the outer beHows-shaped sleeve 2 (for brevity hereinafter referred to only as "bellows 2") , also to protect the same; and a pair of opposite tubular heads 6,7, symmetrical one to the other and identical in this illustrated case, destined in use to be fluid-tight jointed, by welding, to piping segments to be jointed so as to fluid-tight connect to the latter, also the bellows 2.

The sleeve 3 formed by a mesh pad 4 made of metal wire 5 (also referred to hereinafter for simplicity as "damping element 3") is preferably fitted with radial interference onto the flexible beHows-shaped sleeve 2, radially external to it, by a known process comprising an enlargement process to the elastic limit of the sleeve 3 during its assembly on the bellows-shaped sleeve 2. The metal mesh 4 forming the damping element 3 consists of a tubular metal sock made of inter-locking meshes of braided stainless steel wire 5. Furthermore, the wire mesh 4 forming the damping element 3 preferably has a certain degree of compression, between 20 and 40%.

The bellows-shaped sleeve 2 comprises a plurality of first annular corrugations 8 and a pair of opposite cylindrical terminal ends, 9 and 10, free from corrugations which are coaxially coupled and secured integral and fluid-tightly to the heads 6 and 7, respectively, as will be seen. Furthermore, the bellows 2 comprise second corrugations 11 arranged adjacent to both opposite terminal cylindrical ends 9,10 free from corrugations of the beHows-shaped sleeve 2. The corrugations 11 are gradually decreasing in height with respect to that of the corrugations 8, which corrugations 8 are however substantially identical. In particular, the height of the corrugations 11 progressively decreases as the corrugations 11 approach the same ends 9,10. According to the invention, the sleeve 3 in the form of the mesh pad 4 made of metal wire 5 is mounted in forced contact with at least the annular corrugations 8 and the opposite ends 12 and 13 of the sleeve 3, symmetrical to each other, are axially locked with respect to the beHows-shaped sleeve 2, each directly on a respective annular flange 14 integrally obtained in one piece with a respective head 6 and 7; the ends 12,13 are radially locked on the exterior of the respective heads 6,7 with respect to the bellows-shaped sleeve 2.

In particular and specifically referring to Figure 2, which illustrates, on an enlarged scale, a detail of the head 6, the ends 12 and 13, in correspondence of their respective terminal edges, are peripherally crimped to the flanges 14 straddling said flanges 14 by means of respective rings 15 mounted so as to be rammed U-folded on respective edges 16 (Figure 2) radially external to the flanges 14, so that each ring 15 sandwiches a U-folded portion 17 of the respective ends 12,13 of the damping element 2, against opposite flat faces of the respective flange 14, arranged perpendicular to the axis A. The damping element 3 made in the form of a cylindrical sleeve formed by a mesh pad 4 made of metal wire 5 has truncated- conical, front fitting portions 18,19 arranged between the respective U-folded portions 17 of its ends 12, 13 crimped to the flanges 14 and the rest of the sleeve 3 in contact with the corrugations 8.

According to an aspect of the invention, the flanges 14 are shaped and positioned so that the U-folded portions 17 of the ends 12,13 of the damping element 3 crimped onto the flanges 14 keep said front fitting portions 18,19 in forced contact against the corrugations 11 of the bellows-shaped sleeve 2 having a gradually reduced height and arranged adjacent to the cylindrical ends free from corrugations 9,10 thereof, in order to reinforce the actual area of the bellows 2 most heavily affected in use by vibration, while the rest of the sleeve- shaped damping element 3 is fitted with radial interference on respective crests of at least part of the corrugations 8.

Each head 6,7 is formed by a first annular element 20, radially arranged on the interior with respect to the bellows 2 and a second annular element 21 radially arranged on the exterior with respect to the bellows 2 and coaxial with the annular element 20; the cylindrical ends 9,10 free from corrugations of the bellows 2 are each radially sandwiched between the annular element 20 and the annular element 21 of each head 6,7.

In addition, each annular flange 14 obtained in one piece with each head 6,7 consists of a terminal edge of the second element 21 of the respective head, facing towards the corrugations 8,11 of the bellows 2 and which is L-folded radially outwards.

Finally, the annular element 20 of each head 6,7 axially extends so as to protrude within a segment of the bellows- shaped sleeve 2 adjacent thereto, provided with at least some corrugations 11.

In particular, the joint 1 preferably comprises a known flow- guide tubular element 22 or "liner", concentrically arranged inside the flexible beHows-shaped sleeve 2 and made of a crimped metal tape, helically wound so as to form a tube, which is arranged so as to be radially spaced from the bellows 2 and integrally fitted, by its opposite ends, on respective segments 23 of the annular elements 20 of the heads 6,7, which axially extend so as to protrude within the bellows 2.

The heads 6,7, which would still be necessary to hold the liner 22, which, in use, greatly reduces the noise of the exhaust pipings of engines equipped with the joint 1, thus allow, due to the invention, to attach the damping element 3 so as to increase its effectiveness, particularly in correspondence of the corrugations 11, the most stressed, and at the same time so that respective frontal edges 24 of the heads 6,7, facing away from the corrugations 11, remain entirely free from the pad 3. In order to further improve the weldability of said edges 24, they are step-shaped, by simply making the corresponding portions of the elements 20,21 of each head 6,8 with different lengths.