WO1997004223A1

WO1997004223A1 - Exhaust-gas system for an internal-combustion engine and method of manufacturing the manifold of such a system

Info

Publication number: WO1997004223A1
Application number: PCT/EP1996/003124
Authority: WO
Inventors: Klaus Sitzler; Manfred Hein
Original assignee: Dr. Ing. H.C.F. Porsche Aktiengesellschaft; Heinrich Gillet Gmbh & Co. Kg
Priority date: 1995-07-18
Filing date: 1996-07-16
Publication date: 1997-02-06
Also published as: DE59604294D1; DE19526086A1; EP0787248A1; EP0787248B1; KR970706446A; JPH10510025A

Abstract

The internal-combustion-engine exhaust-gas system proposed has a manifold (10) with a wall (17) in the surface of which at least one exhaust pipe (8) ends. The wall (17) is made of a flat steel sheet which has been wound round and joined together at a longitudinal seam (20) to form a cylindrical tube. The point or points of entry (21) of the exhaust pipes (8) are at a distance from this longitudinal seam (20).

Description

Exhaust system of an internal combustion engine and method for producing the collection chamber of an exhaust system

The invention relates to an exhaust system of an internal combustion engine according to the preamble of claim 1 and a method for producing the collecting chamber of an exhaust system according to the preamble of patent claim 6.

Such an exhaust system of a Brennkratt engine is known from DE 40 24 801 A1, in which two exhaust pipes open approximately vertically into a collecting chamber arranged between two catalysts. The collection chamber and the respective adjacent catalysts are formed in an oval-cylindrical metal housing. No details are given in the cited publication on the detailed structure of the collecting chamber or the metal housing and on its manufacturing process. However, two mainly used manufacturing methods for such a collecting chamber or a corresponding housing are known. On the one hand, such housings or collecting chambers are manufactured using the so-called internal high pressure forming process (IHU). Furthermore, it is known to make such collecting chambers or such housings from preformed half-shells; put together. The production of such a collecting chamber in the internal high-pressure forming process leads to relatively long production times, particularly in the case of large series production, since the actual molding process for the collecting chamber or the housing takes 30 s and longer in part. This leads to long production times and is therefore very cost-intensive. In addition, the base materials that can be used for such a production process are expensive, so that the costs for the starting material also increase the overall costs for the production of such an exhaust system. When constructing such an exhaust system with a collecting chamber using half-shell technology, in addition to the relatively high tool costs, there are also disadvantages with regard to the overall strength of such an exhaust system and complex manufacturing steps. The formation of such an exhaust system with a collecting chamber in the half-shell construction leads to connecting seams (weld seams) of considerable length. In addition, these are

ORIGINAL DOCUMENTS Welding seams for manufacturing reasons at least partially in the area of the incoming exhaust pipes, so that on the one hand elaborately shaped weld seams are required, and on the other hand, due to the structural changes occurring in this context, strength-related interventions in stress or bending-critical areas are carried out.

The invention is based on the object to improve an exhaust system according to the preamble of the main claim to the effect that it has a simpler construction and is simpler, faster and more cost-effective to manufacture. In addition, favorable cross-sectional profiles and connection methods are to be made possible, in particular in the inlet region of the exhaust pipes. 3ie are improved with regard to component rigidity, stress curve and permanent bending / vibration resistance.

This object is achieved with the characterizing features of claims 1 and 6, respectively.

If the lateral surface of the collecting chamber is made from a wound sheet metal, which is closed with a longitudinal seam to form a hollow body, and the longitudinal seam runs at a distance from the entry point (s), unfavorable seam profiles in the entry area of the exhaust pipes are avoided compared to the half-shell construction. This also avoids structural changes in this area, so that overall a lower component rigidity and an improved fatigue strength or fatigue strength is achieved and smoother transitions at the entry points are possible. Compared to training in half-shell technology, this leads to significant improvements with regard to the fatigue strength of such a system. In addition, compared to the half-shell construction, the production is simplified or less expensive, since the comparatively short seam area means that much less welding effort is required.

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

The manufacture of such an exhaust system is simplified if the longitudinal seam is formed on the side of the jacket opposite the entry points. This makes it possible with respect to the entry points to have a shape that is uniformly curved on both sides and that is particularly easy to bend. In addition, the relatively large distance between the entry points and the longitudinal seam prevents the occurrence of undesirable stress profiles.

The connection of the exhaust pipes to the collecting chamber can be produced particularly easily and has a more favorable course with regard to the fatigue strength if circumferential edges which are drawn outwards are formed in the region of the entry points and which are connected to the outlet exhaust pipes. These peripheral edges can be formed from a preformed sheet metal element by a relatively simple forming process. Appropriate shaping ensures a transition between jacket and exhaust pipe which is favorable with regard to the bending strength or bending stiffness.

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

Fig. 1 is a schematically illustrated internal combustion engine and its exhaust system. Fig. 2 is a partially shown view of this exhaust system, partially in

Cut. Fig. 3 shows a cross section through the collection chamber of the exhaust system along the

Line III-III in FIG. 2.

An internal combustion engine installed in a motor vehicle has - without limitation to this embodiment - two cylinder rows 1, 2 in a boxer arrangement. On their cylinder heads 3, 4 there are exhaust pipes 6 starting from individual cylinders 5 arranged, which are brought together in a nozzle 7 per cylinder row 1, 2. Further manifold exhaust pipes 8 are connected to these nozzles and feed the exhaust gas from the cylinder banks 1, 2 to a housing 9. This housing 9 extends at the rear of the internal combustion engine transversely to its longitudinal direction ^? and has an approximately circular shape in cross section (FIG. 3). The two collecting exhaust pipes 8 open into a collecting chamber 10 formed centrally in this housing 9, on the two end faces of which a catalyst 12 formed from two monoliths 11 is connected. On the end of the catalytic converters 12 facing away from the collecting chamber 10, the housing 9 is closed by a connecting cover 13, from which a pipeline 14 emerges which opens into a rear silencer 15, which is connected to the atmosphere via an end pipe 16.

The collecting chamber 10 has a cylindrical jacket 17, which consists of a wound sheet metal and is enclosed on its front sides by the jacket 18 of the respectively adjacent catalyst 12 and a housing 19 encompassing it. The front ends of the collecting chamber 10 or its jacket i7, the jacket 18 of the catalytic converter 12 and the further housing 19 are firmly connected to one another by a circumferential weld seam (not shown in more detail). The jacket 17 of the collecting chamber 10 consists - as already mentioned above - of a flat sheet metal plate which is formed into a cylindrical tube by winding and welding on a longitudinal seam 20. Opposite the longitudinal seam 20, two inlet openings 21 are formed in the jacket 17, each of which is provided with a peripheral edge 22. These each form a type of sleeve into which the free ends 23 of the collecting exhaust pipes 8 are inserted. The exhaust gas pipes 8 and the jacket 17 are firmly connected to one another by a welded seam (not shown in more detail) in the region of the front end of the sleeve-shaped edges 22.

in connection with future legal limit values or

Monitoring regulations (OBD II) may require a separation of the exhaust lines of cylinder banks 1 and 2. It is possible to do this in the collection chamber 10 to use a partition 24, which consists of an approximately plate-shaped sheet metal and is inserted during assembly from one of the open end faces into the collecting chamber 10 and positioned and fastened between the two inlet openings 21.

The jacket 17 of the collecting chamber 10 consists - as previously mentioned - of a wound sheet. The starting workpiece for the collecting chamber 10 or its jacket 17 is a flat sheet metal plate which is formed in several process steps. The flat sheet metal blank, which is cut to the intended dimensions, is bent in a U-shape in a first shaping step, the radius of curvature corresponding to the radius of the collecting chamber 10. Domes or sockets pointing outward are drawn into the curved outer surface of the U-shaped intermediate piece by means of a stamp and a counterform. In a further process step, these domes are pre-drilled in the area of their cover and then widened such that the walls run approximately parallel and their inside diameter corresponds to the outside diameter of the exhaust pipes 8. These pre-punched 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, the parallel legs of the U-shaped intermediate part are rolled up, so that a cylindrical shape is formed. The two end faces of the wound sheet, which are now adjacent to one another, are joined together by welding in a longitudinal seam. Other shapes of the weld seam are easily possible. For example, the longitudinal seam can be overlapping or with bent edges. In further process steps, the exhaust pipes 8 are inserted into the inlet openings 21 with their peripheral edges 22 and connected to the jacket 17 by an annular seam. The front ends of the collection chamber are connected to the jacket 18 of the catalysts 12 and the further housing 19. This is also done via a circumferential, ring-shaped weld.

The cross-sectional shape of the jacket 17 of the collecting chamber 10 is not limited to the circular cylinder shape described. It is easily possible for example, to form oval-cylindrical or also asymmetrically curved cross-sectional areas.

The described design of a collecting chamber can also be used without difficulty in the merging of several exhaust pipes, for example in the exhaust pipe manifold area. Thus, in the exemplary embodiment described above, instead of the nozzle 7, a correspondingly constructed collecting chamber can be arranged, into which, for example, two exhaust pipes open laterally (in the jacket) and one exhaust pipe open on the front.

Claims

claims

1.Exhaust system of an internal combustion engine with a collection chamber (10) with a jacket (17) which is curved over at least part of its length and is made of sheet metal and at least one exhaust pipe (8) entering the collection chamber from the side, the entry point (21) of the exhaust pipe in of the lateral surface, characterized in that the jacket (17) of the collecting chamber consists of a wound sheet and that the two peripheral ends of the sheet are connected with a longitudinal seam (20) which runs at a distance from the entry point (s) (21) .

2. Exhaust system according to claim 1, characterized in that the longitudinal seam (20) is formed in the area of the jacket (17) opposite the entry point (s) (21).

3. Exhaust system according to claim 1 or 2, characterized in that at least two entry points (21) are formed in the jacket (17), which are arranged in the longitudinal direction, approximately parallel to the longitudinal seam (20).

4. Exhaust system according to one of the preceding claims, characterized in that the entry points (21) from the outer surface drawn to the outside, rotating

Have edges (22) which are connected to the opening exhaust pipes (8).

5. Exhaust system according to one of the preceding claims, characterized in that the jacket (17) is cylindrical.

6. Method for producing the collection chamber of an exhaust system according to one of the

Claims 1 to 5, characterized by the process steps:

- bending a flat sheet metal plate in a U-shape,

- forming a dome / domes for the exhaust pipe (s) (8), * s - forming an opening in the dome,

- rolling in the U-shaped sheet metal plate,

- Making a longitudinal seam (20).

7. The method according to claim 6, characterized in that the formation of the opening in the dome takes place in two substeps:

- prepunching the cathedral,

Widening the pre-punched opening,