DE102008014144A1 - Connecting end with torsional degree of freedom and process for its preparation - Google Patents

Abstract

It describes a terminal end for line elements, which has a torsional degree of freedom. It is characterized in that it consists of at least one inner tube piece and at least one outer tube piece, wherein the inner tube piece and the outer tube piece have at its cylindrical contours auxiliary elements which generate a positive connection in the radial and axial direction during operation and have a degree of freedom in the torsional direction.
The axial and torsional degrees of freedom are coupled via a helical connection. This ensures that an assembly of terminal end and flexible conduit member can be brought to a defined axial length when installed in a pipeline.

Description

The invention relates to the connection end of a line element for vibration-stressed pipelines. It represents a further development to the main patent DE 10 2007 036 453.0 Examples of applications are exhaust pipes in motor vehicles, preferably in commercial vehicles but also in passenger cars.

The The task of such connection ends is to provide individual line elements to connect with piping systems. An example of this is flexible piping elements that decouple vibrations and operating movements are integrated into exhaust pipes and to their connection in the piping described below Connecting ends find use.

Due to the already existing in the passenger car sector demand for gas tightness, the terminal ends of the flexible conduit elements are usually welded to the adjacent exhaust pipes. A metal bellows is often a module of such flexible conduit elements. Since the large diameter differences in the corrugations of the metal bellows can create turbulence in the exhaust gas flow, in many cases a metal hose is integrated into the conduit member to avoid vortex formation in the flow. DE 198 20 863 A1 shows an example of a flexible conduit element. In the area of the terminal ends of the inner metal tube and the outer metal bellows are processed by radial deformation such that a completely metallic contact between the outer circumference of the metal tube and the inner circumference of the metal bellows consists. In this area, a piece of pipe is then introduced and connected by a circumferential weld in all degrees of freedom with the line element.

In the exhaust pipes of commercial vehicles occur due to operating movements, Mounting position and geometric arrangement increases torsional movements on, which must be compensated by flexible conduit elements. Here are often multi-layered, wound metal hoses made of profiled strip material used as a decoupling element. In particular for use in exhaust systems of commercial vehicles these are particularly suitable because they, in contrast to metal bellows, large torsional movements without the development of structural stresses can decouple. Their disadvantage, however, is the remaining one Residual leakage.

There worldwide legal regulations pollutant emissions of Regulate Commercial Vehicles Significantly Down In The Future Exhaust systems are increasingly with after-treatment modules such. B. Equipped with particulate filters and SCR systems. A Remaining residual leakage through the untreated exhaust gas can escape from the system is only in limited Form allowed. The use of a metal bellows as a flexible and at the same time gastight line element is often difficult here, because the orthogonal to the rotation axis arranged bellows waves before especially in the torsional load case to large voltages and Voltage gradients in the metallic structure lead and thus limit the life of the conduit element.

A solution intended to compensate for larger torsional movements, consisting of two joined, helically corrugated or ring-corrugated metal bellows, is disclosed in US Pat DE 198 24 095 C2 described. It provides for the use of at least two conventional metal bellows, which have a comparable torsional stiffness, so that axial, lateral and torsional movements are distributed at a comparable height to the metal bellows. A larger torsional angular rotation is thus possible, but it does not result from a lower torsional stiffness of the individual components, but only from the doubled by the coaxial Balganordnung way of power flow over the entire decoupling element. The load collective occurring in the operating state is still composed of axial, lateral and torsional movements, which is not optimal from the point of view of operational stability.

DE 103 54 782 B3 shows a further embodiment of a suitable for torsional movements decoupling element. It consists of at least two exhaust gas-carrying, bellows-like components, which are arranged with an axial offset parallel to the axis or skewed to the tube axis of the adjacent conduit system, that the torsional displacements to be compensated by the bellows-like geometries are kept negligibly small. The disadvantage here is that the exhaust stream must be shared.

in the optimal case should not be divided by the conduit element Exhaust flow take place. Furthermore, it is advantageous the torsional To eliminate movements from the load collective of the metal bellows.

In addition to this already in the main patent DE 10 2007 036 453.0 Prior art reported, it is advantageous to incorporate metal bellows and similar kind of components in their neutral, non-stress and stress-free position in the piping systems, as caused by installation tolerances bias overlap the later operating voltages and thus produce a negative impact on the fatigue strength.

Object of the invention in the main patent DE 10 2007 036 453.0 It is therefore necessary to provide a connection end which keeps the torsional movements compensated by the flexible conduit element negligibly small. The entire load collective for the bellows-type geometries to be used thus reduces to axial and lateral displacements. In this way, a simpler design of the line element is made possible and, above all, a significantly increased service life is achieved since the torsional damage components due to the decoupling are eliminated

The Additional task is defined by the requirement for voltage-free Installation of flexible conduit elements, by the design of the realized end of the connection described here. After that, one should further degree of freedom contained in the torsional connection end create an axial displacement possibility. This axial Displacement should only once during installation of the flexible element together with the described connection end in the line system respectively. In later operation, only the torsional Degree of freedom available to compensate for operational movements.

The Task is according to the invention with the features of claims 1 and 2 solved. Advantageous embodiments are included in the subclaims.

The Terminal end according to the invention will consist of at least composed of two pieces of pipe. Here is the outer diameter of the inner pipe section smaller than the inner diameter of the outer pipe section. Both pipe pieces in assembling, preferably produced in a forming operation Undercuts on, allowing a positive connection in the radial direction and a degree of freedom in the torsional direction is present. To realize the axial adjustability during installation the undercuts are spiraling around the circumference of the Pipe pieces arranged.

The thus formed thread made possible by the rotation of the Pipe pieces an axial length adjustment. A advantageous geometric design of the invention provides a thread pitch of 20 mm per 360 ° before, so that the pipe sections realize a length compensation of 40 mm with two turns can.

To the installation, the pipe sections are twist-resistant in the pipe system positioned to each other. Torsional operating movements of the pipe system are within ± 5 °. When torsional compensation become axial movements by the thread pitch in the connection end generated, which are well below ± 1 mm and thus are negligibly small.

in the Range of contact surfaces between inside and outside lying pipe section is preferably an intermediate that has both a sealing effect and sliding properties having. This structure allows a helical, combined torsional and axial displacement under flow in conjunction with a minimal residual leakage. Alternatively you can to the one intermediate also several different intermediates present, each take over the sealing function or the sliding function. These intermediates can be used according to their function solid and brittle, ductile, pasty or liquid be.

• – Gestrickte und gepresste Elemente aus Edelstahlfasern und Graphitfasern.
• – Gestrickte und gepresste Elemente aus Edelstahlfasern und saugfähigen Fasern, an denen durch Tauchen in eine Flüssigkeit eine Graphit-Anlagerung erzeugt wird.
• – Precursorbeschichtetes Gewebe, bei dem der Grundwerkstoff Aluminiumoxid ist.
• – Precursorbeschichtetes Gewebe, bei dem der Grundwerkstoff glasartig ist.
• – Ein präkeramisches Polymer in fester, pastöser oder schaumförmiger Konsistenz.
• – Mit temperaturbeständigem Gleitwerkstoff beschichtetes Metall.
• – Mit präkeramischen Polymeren beschichtetes Metall.
• – Faserverstärktes Graphitband.
• – Temperaturbeständiger Gleitlack.

The following intermediates are exemplary, but not exhaustively suitable in the list for the application:

• - Knitted and pressed elements made of stainless steel fibers and graphite fibers.
• - Knitted and pressed elements made of stainless steel fibers and absorbent fibers, which are dipped in a liquid to create a graphite attachment.
• - Precursor-coated fabric in which the base material is alumina.
• Precursor-coated fabric in which the base material is vitreous.
• - A preceramic polymer in a solid, pasty or foamy consistency.
• - Metal coated with temperature-resistant sliding material.
• - Metal coated with preceramic polymers.
• - Fiber reinforced graphite tape.
• - Temperature-resistant bonded coating.

As well Combinations of the mentioned intermediates can especially suitable for special applications be.

The Undercuts preferably have large contours Radii and can be helical be.

1 shows a system of internal pipe ( 11 ), outer tube ( 12 ) and intermediate ( 13 ), in which the undercut between the two pipe sections has radii R1, R2. These are preferably the same or, depending on the installation position and function, also have different values. In addition to the torsional degree of freedom can be compensated by this configuration, angle deviations between the axes of the pipes to be joined. In the end areas 111 and 121 The pipes to be connected are connected. This connection can preferably z. B. form fit by a circumferential weld. There is also the possibility of the areas 111 and 121 in a form processing such that any, V- or spherical connection geometries arise, as they are common in pipeline construction.

2 shows a system of internal pipe ( 21 ) and outer tube ( 22 ), in which the undercuts between the two pipe sections are thread-like. Between the two tubes is an intermediate substance ( 23 ) having both sealing and sliding properties. The thread length of one of the two pieces of pipe must exceed that of the other by the amount of the desired axial adjustability.

Further Variants of the connection ends described are conceivable and based on the basic concept described above, which is the torsional Degree of freedom allows the radial locks and the axial over a thread-like geometry made adjustable.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 102007036453 [0001, 0009, 0010]
• - DE 19820863 A1 [0003]
• - DE 19824095 C2 [0006]
• - DE 10354782 B3 [0007]

Claims (4)

Connecting end with torsional degree of freedom, characterized in that it consists of at least one inner tube piece and at least one outer tube piece, wherein the inner tube piece and the outer tube piece have on their cylindrical contours side elements that produce a positive connection in the radial direction and combined in the axial and torsional direction via a helical connection have a degree of freedom. Connecting end with torsional degree of freedom, by characterized in that it consists of at least one inner tube piece, at least one outer pipe section as well consists of at least one precursor, with the inside lying Pipe piece and the outer pipe piece have their cylindrical contours auxiliary elements that a generate positive connection in the radial direction and combined in the axial and torsional direction over a helical connection one degree of freedom to have. Connecting end with torsional degree of freedom Claims 1 or 2, characterized in that it contains two different intermediates, according to a Functional separation an intermediate the torsional sliding properties and the second realized the sealing effect. Connecting end with torsional degree of freedom according to claims 1 or 2, characterized in that two different intermediate substances are each arranged several times in the parting plane between the inside and outside lying pipe section. ( 1 )