Connection of two pipes and sealing ring for the connection

In a pipe connection, a first pipe has a first flange of sheet metal provided with a first wall connected circumferentially to the first pipe. A second pipe has an end section shaped as a second flange. A clamp engages across the first and second flanges and has conical sidewalls forcing the first and second flanges axially against one another when tightening the clamp. The first flange delimits together with the first pipe an annular chamber that is coaxial to the longitudinal pipe axis. The first flange has a second wall that is glidingly supported on a free end of the first pipe. A sheet metal sealing ring is positioned between the first and second flanges. It has an edge section that is bent back onto a remaining sealing ring section that has a corrugation projecting past the bent edge section in an untightened state of the clamp.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a connection of two pipes, wherein a first pipe has a first flange of sheet metal that is connected with a first wall to the pipe circumference and wherein a second pipe has an end section that is shaped as a second flange. The connection comprises a tightenable clamp engaging across the two flanges and provided with conical sidewalls by which the flanges when the clamp is tightened are forced axially against one another. Moreover, the invention relates to a sealing ring for such a connection.

2. Description of the Related Art

A connection of this kind is disclosed as a schematic detail illustration in the brochure No. 6 “NORMA® PROFILSCHELLEN KEGELFLANSCHVERBIDNUNGEN”; Sep. 1987, page 6, left column, upper figure. This connection shows the free ends of both flanges contacting one another wherein the two flanges delimit an annular chamber together with the first pipe to which the first flange is welded. When the pipes to be connected are components of an exhaust gas manifold of a motor vehicle, very hot exhaust gases at a temperature of approximately 900 to 1000° C. pass through the pipes. Accordingly, the pipes are heated to very high temperatures so that they expand (widen) radially to a greater extent than the clamp that is exposed to a reduced temperature because it is positioned radially outwardly and therefore can be over-extended and rupture.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a pipe connection of the aforementioned kind in which the clamp is subjected to a reduced thermal load.

In accordance with the present invention, this is achieved in that the first flange delimits together with the first pipe a closed annular chamber that is coaxial to the longitudinal axis of the first pipe, wherein a second wall of the first flange is glidingly supported on the free end of the first pipe.

In accordance with this solution, the first flange remains relatively cool because of the air that is enclosed in the closed annular chamber. The first flange thermally widens therefore to a lesser degree but can bend radially inwardly relative to the first pipe under the thermal radial expansion pressure of the first pipe while being supported on the clamp because the wall that is not welded to the first pipe can glide across the free end of the first pipe so that the radial expansion pressure of the first pipe can be compensated for the most part by the bending action of the first flange without being transmitted completely onto the clamp.

Preferably, the free end of the first pipe is beveled. On this bevel of the first pipe the second wall of the first flange can glide more easily under radial thermal expansion pressure.

When the second wall of the first flange is supported with a rounded portion on the free end of the first pipe, the second wall of the first flange can glide even more easily on the bevel of the first pipe under the radial expansion pressure.

It is preferred to provide the second pipe between the second flange and the remaining pipe section with an elastically bendable cylindrical section. By means of the radial elastic bending action of the cylindrical section, a great portion of the radial expansion pressure of the second pipe can be taken up. At the same time, the elasticity of the cylindrical section allows an angled arrangement or radial displacement of the two pipes relative to one another when, as a result of a minimal assembly error, they are not precisely coaxially aligned with one another.

Moreover, the inner diameter of the cylindrical section can be greater than the outer diameter of the first pipe. This makes it possible that the transition section of the second pipe between the cylindrical section and the remaining pipe section of the second pipe connected thereto can bend under the axial thermal expansion pressure of both pipes so that it provides an axial expansion compensation in this way.

Preferably, it is moreover provided that the rounded portion of the second wall of the first flange passes into a cylindrical projection and the inner diameter of the cylindrical section of the second pipe is greater than the outer diameter of the projection. This configuration has the advantage that a gap or play is provided between the cylindrical projection of the second wall of the first flange wherein the projection also forms at the same time a cylindrical projection of the first pipe that facilitates insertion of the two pipes into one another because the second pipe is guided on the projection. At the same time, both pipes can be centered substantially in this way when they are not coaxially inserted into one another initially.

It is moreover beneficial when the transition section between the cylindrical section and the remaining pipe section of the second pipe connected thereto is conical. The conical configuration and elasticity of the transition section facilitate also a radial thermal expansion of the remaining pipe section of the second pipe relative to its cylindrical section and the second flange so that the radial thermal expansion pressure of the second pipe onto the clamp can also be partially compensated by the transition section.

A further advantageous configuration resides in that the connection between the flanges has a sealing ring in the form of an elastic sheet steel strap with at least one edge section which is bent back onto a portion of the remaining sealing ring section and in that the remaining sealing ring section has at least one corrugation that projects past the thickness of the bent edge section in the untightened state of the clamp. This sealing ring withstands, on the one hand, high temperatures as they are encountered in exhaust gas pipes but is still elastic within the area of its corrugation. This corrugation not only receives the tightening pressure but also the axial thermal expansion of both pipes relative to one another without being deformed completely to a plane shape (back deformation). This back deformation is prevented in that the bent-back edge section or sections acts or act as a stop for the second flange of the second pipe and, in this way, prevents or prevent a further back deformation of the corrugation. The elasticity of the corrugation remains substantially intact and contributes to the reduction of thermal axial load of the clamp by thermal expansion of the pipes.

Each edge section can be in the form of a tab that can be more easily bent than a continuous circumferential crimped edge section of the sealing ring that extends across the circumference of the remaining edge section of the sealing ring.

The corrugation extends preferably across the entire circumference of the sealing ring. It can therefore be formed by a simple stamping tool.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The connection inFIGS. 1 and 2of a first pipe1to a second pipe2by means of a tightenable clamp3comprises a first flange4of springy sheet metal having a slanted first wall5and a slanted second wall6. The wall5is welded to the periphery of the first pipe1. The wall6is supported by a rounded portion7glidingly on a bevel8provided on the free end of the first pipe1. The bevel8is positioned at an acute angle of approximately 30° relative to the axial direction of the pipe1. The rounded portion7passes into a cylindrical projection9whose inner and outer diameters are identical to the inner and outer diameters of the first pipe1. The flange4encloses therefore together with the first pipe1an annular chamber that is filled with air.

An end section of the second pipe2forms a second flange10.

The clamp3engages across the flanges4and10and pulls together the two flanges4and10when tightening the clamp3by means of conical sidewalls11and12that are provided in the circumferential direction at identical angular spacings with interruptions13(FIG. 4) in order to flexibly secure an outer clamping strap14and thus the entire clamp. The clamp3is tightened by means of a screw15. The screw15is passed through coaxial holes in a hinged sleeve16and through coaxial threaded holes in a hinged sleeve17. The hinged sleeves16,17are surrounded by loops18that are formed by bent-back end sections of the tightening strap14. The bent-back ends of the loops18are welded onto the remaining part of the tightening strap14. The clamping screw15passes through slots in the loops18.

The second pipe2has an elastically bendable cylindrical section20between the second flange10and the remaining pipe section19of the second pipe2. The inner diameter of the cylindrical section20is greater than the outer diameter of the first pipe1and of the cylindrical projection9. The transition section21(FIG. 1) between the cylindrical section20and the remaining pipe section19of the second pipe2is conical and also elastically bendable.

A sealing ring22of springy sheet steel is clamped in the tightened state of the clamp3between the two flanges4and10.

As illustrated inFIGS. 2 and 5through7in more detail, eight edge sections23in the form of tabs are bent back onto a portion of the remaining sealing ring section24. The remaining sealing ring section24has a corrugation25that projects past the thickness of the bent-over edge sections23in the untightened state of the clamp3; the corrugation25extends across the entire circumference of the sealing ring22. The radial inner edge of the sealing ring22is provided at identical circumferential spacings to one another with three compensation tabs26that are curved in accordance with the rounded portion7.

In the following the function and advantages of the illustrated embodiment will be explained in more detail.

Because of the air that is enclosed in the annular chamber between the first flange4and the first pipe1, the flange4remains relatively cool when a hot fluid, for example, hot exhaust gas, is passed through the pipes1and2. The first flange4accordingly widens thermally in the radial direction to a lesser degree than if it were in direct contact with the hot fluid. However, under the thermal radial expansion pressure of the first pipe1, it can radially bend inwardly by being supported on the clamp3because the wall6that is not welded to the first pipe1can glide along the free end of the first pipe1so that the radial expansion pressure of the first pipe1can be received for the most part by the bending action of the flange4without being completely transmitted onto the clamp3. The bevel8of the first pipe1contributes in particular to this action because the wall6of the flange4can glide along the bevel8when exposed to the radial thermal expansion pressure and the counteracting pressure provided by the clamp3. Additionally, the rounded portion7of the wall6of the flange4facilitates the gliding action of the wall6on the bevel8.

The elastic cylindrical section20has the advantage that it is bent under the thermal expansion pressure in the second pipe2and thus also takes up a portion of the expansion pressure. At the same time, the elasticity of the cylindrical section20enables an angled arrangement of a radial displacement of the two pipes1,2relative to one another when they are not precisely coaxially aligned with one another as a result of minimal assembly errors.

Since the inner diameter of the cylindrical section20is greater than the outer diameter of the first pipe1, the transition section21of the second pipe2between the cylindrical section20and the pipe section19of the second pipe2connected thereto can bend under the axial thermal expansion pressure of both pipes1,2and therefore can ensure axial expansion compensation.

The cylindrical projection9of the rounded portion7of the second wall6of the flange4has the advantage that a gap or play results between the cylindrical projection9of the wall6of the first flange4and the cylindrical section20wherein the projection9at the same time forms a cylindrical projection of the first pipe1and facilitates the insertion of both pipes into one another because the second pipe2is guided on the projection9. At the same time, both pipes1,2can be centered substantially when they are not coaxially inserted into one another initially.

The conical configuration and elasticity of the transition section21facilitated also a radial thermal expansion of the remaining section19of the second pipe2relative to its cylindrical section20and the second flange10so that the radial thermal expansion pressure of the second pipe2onto the clamp3is compensated partially also by the transition section21.

The sealing ring22comprised of sheet steel withstands, on the one hand, high temperatures as they are encountered especially in exhaust gas pipes, but is still elastic in the area of its corrugation25, on the other hand. This corrugation25not only takes up the tightening pressure of the clamp3but also partially the axial thermal expansion of both pipes1,2relative to one another without being completely deformed into a plane shape. This back deformation is prevented in that the bent-back edge sections23or tabs serve as a stop for the second flange10of the second pipe2. The elasticity of the corrugation25remains thus substantially intact. Instead of providing edge sections23distributed about the circumference of the sealing ring22, it is also possible to provide a continuous circumferential edge section about the entire circumference of the sealing ring22by crimping. Individual edge sections23in the form of tabs however can be bend more easily than a continuous circumferentially extending edge section of the sealing ring22that is crimped about the circumference of the remaining sealing ring section24.

The corrugation25extends preferably across the entire circumference of the sealing ring22. Therefore, it can be formed by a simple stamping tool. Alternatively, it is also possible to divide the corrugation25into individual corrugations or to provide radial corrugations that are distributed about the circumference of the sealing ring22. However, the latter would have as a whole a higher stiffness than the corrugation25extending about the entire circumference of the sealing ring section24.