DE20220500U1 - IC engine exhaust comprises inliner and jacket held apart by spacer made of braided wire which is held in annular groove made by bending third pipe whose downstream end is fixed to liner or jacket - Google Patents

Abstract

The IC engine exhaust comprises an inliner (2) and a jacket (3). These are held apart by a spacer (9) made of braided wire which is held in an annular groove (12 -14) made by bending a third pipe whose downstream end (19) is fixed to the liner or jacket.

Description

Our reference: 757 Benteler (-007)

Benteler Automobiltechnik GmbH Residenzstrasse 1, D-33104 Paderborn

Compensation element for guiding exhaust pipes

The invention relates to an exhaust pipe with air gap insulation for an internal combustion engine according to the features in the preamble of the patent claim.

Exhaust pipes in internal combustion engines can be made of pipes, but sometimes also of sheet metal parts. In particular in air gap-insulated front pipes of exhaust pipes in internal combustion engines, the different expansion of the individual components (inliner -> pipe or sheet metal or the jacket that surrounds the inliner at a distance -> pipe or sheet metal) must be taken into account. The different expansion of the components is due to the use of different materials and also to different temperatures. Temperature differences arise because, for example, the inliner component comes into direct contact with the hot exhaust gas.

Contact, while the jacket surrounding the inliner at a distance is insulated from the inliner by an air gap.

If the inliner were to be joined to a jacket, for example by a fusion welding process or by form-fitting, such high stresses would inevitably be generated in the components that would result in the components breaking, especially at high temperatures.

EP 0 503 580 A1 discloses an exhaust pipe with air gap insulation for an internal combustion engine, which has an inliner that carries exhaust gases and a jacket that surrounds the inliner at a distance. One end face of the jacket and one end face of the inliner run in the same transverse plane. A compensating element in the form of a wire mesh with a rectangular cross-section is incorporated into the gap between the inliner and the jacket. This compensating element is clamped in a holder formed by a groove-like fold in a piece of pipe and is supported relatively movably on the outer surface of the inliner. The holder merges into a ring attachment, the length of which corresponds to approximately one third of the width of the compensating element. This ring attachment protrudes so far beyond the common transverse plane of the end faces of the inliner and the jacket that the ring attachment can be axially fixed to the front face of the jacket by means of a fillet weld.

Although this proposal represents an improvement compared to the previously known state of the art, it does not yet take into account the respective local conditions in a truly satisfactory manner with regard to influencing the vibration characteristics of the exhaust pipe. The reason for this is the relatively short axial length of the ring attachment in relation to the significantly larger axial extension (width) of the compensation element.

· · a

The invention is based - based on the prior art - on the object of creating an exhaust pipe with air gap insulation for an internal combustion engine, which can be designed with regard to its vibration characteristics depending on the local conditions while maintaining the known simple structure and problem-free assembly with perfect positional orientation of an inliner within a jacket.

This problem is solved with the features listed in the characterizing part of the patent claim.

An essential feature of the invention is that a front side of a flange attached to the outer circumference of the jacket in the outflow area of the exhaust pipe also extends in the transverse plane in which the front sides of the inliner and the jacket also run. Longitudinal sections protruding beyond the front sides are no longer present. Other essential features of the invention are the fixation of the free end of the cylindrical longitudinal section to the inner surface of the jacket and the relatively movable support of the compensation element on the outer surface of the inliner.

In this context, the invention has recognized that the targeted fixing of the cylindrical length section to the inner surface of the jacket significantly reduces the risk of welding spatter getting into the inliner during welding. Also, within the scope of the invention, the inliner, which is considerably thinner and hotter than the jacket, no longer needs to move both the compensation element and the length section during relative thermal expansion. Finally, the invention has also recognized that the superposition of the high-frequency pulsation vibrations of the exhaust gas can be dampened by the compensation element and thus no longer affects the friction area between the side of the holder facing the jacket and the inner surface of the jacket.

The compensating element therefore reduces friction, meaning that the hot inliner is subjected to less stress.

By combining the features in the characterizing part of the protection claim, the length of the cylindrical length section can now be precisely determined depending on the respective local conditions and thus the vibration characteristics of an exhaust pipe can be specifically influenced. In addition, the resonance behavior and the fatigue strength can be positively influenced.

The invention is explained in more detail below using an embodiment shown in the drawing.

Reference numeral 1 designates an exhaust pipe, in particular in the form of an air-gap-insulated front pipe, for an internal combustion engine not otherwise shown in detail.

The exhaust line 1 comprises a tubular inliner 2 (inner pipe) through which the exhaust gas flows. At a radial distance A from the inliner 2 there is a tubular jacket 3 (outer pipe) that encases the inliner 2. This forms a gap 4 between the inliner 2 and the jacket 3. The end faces 5, 6 of the inliner 2 and the jacket 3 run in the same transverse plane QE. A flange 7 is attached to the outer circumference of the jacket 3, the end face 8 of which also extends in the transverse plane QE.

In the gap 4 between the inliner 2 and the jacket 3, an annular compensating element 9 in the form of a rectangularly configured wire mesh is arranged.

The compensating element 9 is supported with one side 13 on the outer surface 20 of the inliner 2. It is embedded with its sides 10, 12 and 14 in a holder 21, which is formed by folding a pipe section 22. This pipe section 22 has an end flange 23, which is radially

• ··« ■ I» * t · I

is bent on the inside. Its width B2 is shorter than the width A of the gap 4.

At a distance from the end flange 23, the pipe section 22 has an inwardly directed fold 24, the radial width B3 of which is also smaller than the width A of the gap 4. In this way, the compensation element 9 is held securely. It only rests on the inner surface 11 of the jacket 3. It can move, twist or tilt relative to the jacket 3 to a limited extent.

In addition to the fold 24, a cylindrical length section 25 of the pipe section 22 extends adjacent to the inner surface 11 of the jacket 3. Its length L depends on the vibration characteristics of the exhaust pipe 1. Its free end is fixed in the area of the front side 6 on the jacket 3 by spot welding.

Claims (1)

Exhaust pipe (1) with air gap insulation for an internal combustion engine, which has an exhaust gas-conducting inliner (2) and a jacket (3) enclosing the inliner (2) at a distance (A), wherein an end face (6) of the jacket (3) and an end face (5) of the inliner (2) run in the same transverse plane (QE) and a compensating element (9) in the form of a wire mesh having a rectangular cross-section is incorporated into the gap (4) between the inliner (2) and the jacket (3), which is clamped on the inside of the jacket (3) on three sides (10, 12, 14) in a holder (21) formed by a groove-like fold of a pipe section (22) and is supported in a relatively movable manner on the outer surface (20) of the inliner (2), and wherein the free end of a cylindrical length section (25) of the pipe section (22) facing away from the holder (21) in the region of the transverse plane (QE) is axially fixed, characterized in that an end face (8) of a flange (7) fastened to the outer circumference of the jacket (3) in the outflow region of the exhaust pipe (1) also extends in the transverse plane (QE), the free end of the cylindrical length section (25) of the pipe piece (22) is fixed to the inner surface (11) of the jacket (3) and in order to influence the vibration characteristics of the exhaust pipe (1), the length (L) of the cylindrical length section (25) is made dependent on the local conditions.