EP0787248B1 - Exhaust-gas system for an internal-combustion engine and method of manufacturing the manifold of such a system - Google Patents

Description

The invention relates to an exhaust system of an internal combustion engine according to the first part of claim 1 and a method for producing the jacket for a Collection chamber of an exhaust system.

Such an exhaust system of an internal combustion engine is known from DE 40 24 801 A1 known, in the two exhaust pipes approximately vertically in one between two catalysts open arranged collection chamber. The collection chamber and each adjacent catalysts are in an oval-cylindrical metal housing educated. For a more detailed structure of the collection chamber or the metal housing and there are no details of his manufacturing process in the cited publication Information provided.

However, there are two main manufacturing processes used known for such a collection chamber or a corresponding housing. To the one such housing or collection chambers in the so-called Internal high pressure forming process (IHU) manufactured. Furthermore, it is known such collecting chambers or housings of preformed half-shells put together. The production of such a collection chamber in Internal high-pressure forming processes are particularly useful in large-scale production relatively long production times, since the actual molding process for the Collection chamber or the housing sometimes takes 30s and longer. this leads to long production times and is therefore very expensive. In addition, they are for such a manufacturing process usable base materials expensive, so that the Cost of raw material is the total cost of producing one increase such exhaust system. When building such an exhaust system with Collection chamber in half-shell technology come in addition to the relatively high Tool costs disadvantages in terms of the overall strength of such Exhaust system and complex manufacturing steps. The training of such Exhaust system with a collecting chamber in the half-shell structure leads to Connection seams (weld seams) of considerable length. In addition, these are Welding seams for manufacturing reasons at least partially in the area of entering exhaust pipes, so that on the one hand elaborately shaped welds are required, on the other hand by those occurring in this context Structural changes in strength-relevant interventions in stress or bending critical Areas.

From DE-A-38 15 408 is also an exhaust device for Multi-cylinder internal combustion engines are known, one piece to the cylinder head integrally molded cooled exhaust manifold, in the exhaust gas routing from Sheet metal wound tube is inserted. This from a rectangular sheet bent pipe has side openings that the exhaust ports of the cylinder head opposite and serve to introduce exhaust gases into this pipe.

The invention is based on the object, the known exhaust system to improve in that it is easier constructed and easier, faster and cheaper to manufacture. Farther in particular in the entry area of the exhaust pipes into the collection chamber favorable cross-sectional profiles and connection methods are made possible, which in With regard to component rigidity, stress curve and fatigue strength are improved.

This object is achieved with the features of Claims 1 and 5 solved.

Because the outer surface of the collecting chamber is made from a coiled sheet which is closed with a longitudinal seam to form a hollow body, and runs the Longitudinal seams at a distance from the entry point (s) are compared unfavorable seam courses in the inlet area of the exhaust pipes for the half-shell construction avoided. This also avoids structural changes in this area that overall a lower component rigidity and an improved permanent bending or Vibration resistance is achieved and softer transitions at the entry points possible are. This leads in comparison to training in half-shell technology significant improvements with regard to the fatigue strength of such Investment. In addition, the production is compared to the half-shell construction Simplified or less expensive because of the comparatively short seam area much less welding effort is required.

Compared to the internal high pressure forming process (IHU) are much cheaper Starting materials can be used for the formation of such an exhaust system, so that considerable cost savings can be achieved solely through the choice of materials In addition, such an exhaust system can be manufactured faster, so that significant cost advantages can also be achieved with this.

The manufacture of such an exhaust system is simplified if the longitudinal seam is open the side of the jacket opposite the entry points is formed. As a result, a uniformly curved on both sides with respect to the entry points Form course possible, which is particularly easy to bend. In addition, by the relatively large distance between the entry points and the longitudinal seam Avoidance of undesirable voltage profiles avoided.

The connection of the exhaust pipes to the collecting chamber is particularly simple produce and has a more favorable course in terms of fatigue strength, if, in the area of the entry points, peripheral edges drawn outwards are formed, which are connected to the opening exhaust pipes. This circumferential edges can be made from a preformed sheet metal element are formed. By appropriate shaping is a favorable transition in terms of bending strength or bending stiffness ensured between jacket and exhaust pipe.

Fig. 1

eine schematisch dargestellte Brennkraftmaschine und deren Abgasanlage,

Fig. 2

eine nur teilweise dargestellte Ansicht dieser Abgasanlage, teilweise im Schnitt,

Fig. 3

einen Querschnitt durch die Sammelkammer der Abgasanlage entlang der Linie III-III nach Fig. 2.

Further advantages and advantageous developments of the invention result from the dependent claims and the description. The latter shows in

Fig. 1

a schematically illustrated internal combustion engine and its exhaust system,

Fig. 2

a partially shown view of this exhaust system, partly in section,

Fig. 3

a cross section through the collection chamber of the exhaust system along the line III-III of FIG. 2nd

An internal combustion engine installed in a motor vehicle has - without limitation on this embodiment - two rows of cylinders 1, 2 in a boxer arrangement. On theirs Cylinder heads 3, 4 are exhaust pipes 6 emanating from individual cylinders 5 arranged, which are fused together in a nozzle 7 per cylinder row 1, 2. On these nozzles are connected to further collecting exhaust pipes 8, which Feed exhaust gas from the cylinder banks 1, 2 to a housing 9. This housing 9 extends on the back of the internal combustion engine transverse to its longitudinal direction F and has an approximately circular shape in cross section (FIG. 3). The two Collective exhaust pipes 8 open into a centrally formed in this housing 9 Collection chamber 10, on the two end faces of which there is in each case two monoliths 11 trained catalyst 12 connects. On the collection chamber 10 The end face of the catalytic converters 12 is the housing 9 by one each Connection cover 13 closed, from which a pipe 14 extends into one Muffler 15 opens, which is connected to the atmosphere via an end pipe 16 is.

The collecting chamber 10 has a cylindrical jacket 17 which consists of a coiled sheet exists and on its end faces from the jacket 18 of each adjoining catalytic converter 12 and a housing 19 that extends further and encompasses it is enclosed. The front ends of the collecting chamber 10 or its jacket 17, the jacket 18 of the catalyst 12 and the further housing 19 are through a circumferential weld - not shown - firmly connected. The jacket 17 of the collecting chamber 10 consists - as already mentioned - of a flat sheet metal plate, which is wound and wound on a longitudinal seam 20 is formed into a cylindrical tube. The longitudinal seam 20 are opposite formed in the jacket 17 two inlet openings 21, each with one peripheral edge 22 are provided. These each form a kind of sleeve into which the free ends 23 of the collecting exhaust pipes 8 are inserted. Through a circumferential - not shown - weld in the area of the front end of the sleeve-shaped edges 22, the collecting exhaust pipes 8 and the jacket 17 are fixed connected with each other.

In connection with future legal limit values or Monitoring regulations (OBD II) can separate the exhaust lines Cylinder rows 1 and 2 may be required. It is possible to do this in the collection chamber 10 use a partition 24, which consists of an approximately plate-shaped sheet and when assembling from one of the open end faces into the collecting chamber 10 introduced and positioned and fastened between the two inlet openings 21 becomes.

The jacket 17 of the collecting chamber 10 consists - as mentioned above - of one coiled sheet. The starting workpiece for the collection chamber 10 or their Sheath 17 is a flat sheet metal plate that is formed in several process steps is. The level cut to the intended dimensions Sheet metal is bent into a U-shape in a first molding step, the Radius of curvature corresponds to the radius of the collecting chamber 10. In the curved one The outer surface of the U-shaped intermediate piece is formed by a stamp and a counterform pulled outward facing domes or sockets. In another Process step, these domes are pre-punched in the area of their cover and then widened so that the walls run approximately parallel to her Inner diameter corresponds to the outer diameter of the exhaust pipes 8. This prepunched or widened edges of the domes correspond to the sleeve-shaped Edges 22, which serve to receive the exhaust pipes 23. In the next Process step are the parallel legs of the U-shaped intermediate part rolled up so that a cylindrical shape is formed. The two now adjacent ends of the wound sheet are welded in a longitudinal seam joined together. Other forms of the weld seam are without further possible. For example, the longitudinal seam can overlap or with bent edges. In further process steps, the Exhaust pipes 8 into the inlet openings 21 with their peripheral edges 22 used and connected by a ring seam to the jacket 17. The front Ends of the collecting chamber are covered with the jacket 18 of the catalysts 12 and continuing housing 19 connected. This is also done via a circumferential, annular weld.

The cross-sectional shape of the jacket 17 of the collecting chamber 10 is not on the described circular cylindrical shape limited. It is easily possible for example oval-cylindrical or arched in cross-section asymmetrical To form jacket areas.

The described formation of a collecting chamber can easily be done at Merging several exhaust pipes, for example in the exhaust manifold area be applied. So can in the previously described embodiment instead of the nozzle 7, a correspondingly constructed collecting chamber can be arranged in for example, two exhaust pipes on the side (in the jacket) and one exhaust pipe open at the front.

Claims (6)

1. An exhaust system of an internal-combustion engine having a collecting chamber (10) with a jacket (17) formed from metal sheet and curved over at least part of the length thereof, and at least one exhaust pipe (8) entering the collecting chamber laterally, wherein the entry point (21) of the respective exhaust pipe is situated in the jacket surface, characterized in that the jacket (17) of the collecting chamber consists of a metal sheet curved round and closed by a longitudinal seam to form a hollow body, wherein the said longitudinal seam (20) extends at a distance from the entry point or points (21), and the entry point or points (21) is or are provided with continuous edges (22) projecting from the jacket face and connected to the opening exhaust pipes (8).
2. An exhaust system according to Claim 1, characterized in that the longitudinal seam (20) is formed in the region of the jacket (17) opposite the entry point or points (21).
3. An exhaust system according to Claim 1 or 2, characterized in that at least two entry points (21) arranged substantially parallel to the longitudinal seam (20) in the longitudinal direction are formed in the jacket (17).
4. An exhaust system according to one of the preceding Claims, characterized in that the jacket (17) is cylindrical.
5. A method of producing the jacket for a collecting chamber of an exhaust system according to one of Claims 1 to 4, characterized by the method steps:

   curving a flat metal-sheet blank into a U-shape,

   producing entry points for respective exhaust pipes in the curved region of the metal-sheet blank by

   shaping out respective domes extending outwards and used for receiving the respective exhaust pipes,

   forming an opening in each dome,

   curving around the U-shaped metal-sheet blank, and

   forming a longitudinal seam (20) along the mutually abutting front edges of the curved-around metal-sheet blank.
6. A method according to Claim 5, characterized in that the formation of the opening in each dome takes place in two partial steps:

   perforating the dome, and

   widening the perforated opening.

Images