EP0748928B1 - Exhaust manifold with sheet metal inlet pipes - Google Patents

Description

The invention relates to an exhaust manifold with sheet metal Intake pipes from the respective cylinder head outlet through at least a cylinder head mounting flange to a common one Exhaust outlet, with at least one curved inlet pipe is provided.

A major problem of the aforementioned, for example Exhaust manifold known from DE-A-32 16 980 or GB-A-2 058 917 is the durability in operation.

The exhaust manifold is up to approx. 1000 ° C hot exhaust gas at temperatures of a similar magnitude heated up. A sheet metal formed from common steels and assembled component stretches under such conditions by about 1%.

The hot, gas-carrying components of an exhaust manifold are but welded into the cylinder head mounting flange, which is usually a substantially lower temperature level has and therefore also very in operation stretches a lot less. This cylinder head mounting flange or its screwing on the cylinder head thus impedes the thermal expansion of the exhaust manifold.

The disabled thermal expansion now leads to tension, which more or depending on the design of the component are less critical to life. Is the Geometry such that e.g. due to very short pipe runs or due to an unfavorable pipe profile, high rigidity arises, then the tensions become so high that often unsatisfactory service life of exhaust manifolds is achieved.

In the specific case, the constructive freedoms are extreme limited, and there is no way at conventional Construction of an exhaust manifold an adequate To achieve stability. The main cause of the high section modulus of the tubes against a bend that the Could compensate for thermal expansion is what's internal State of the art is the flat, box-shaped profile the tubes of the external cylinders. But this is according to the state of the art required to access the screws of the cylinder head mounting flange if sufficient Flow cross section of the exhaust manifold to reach.

Based on the problems of the known prior art it is an object of the invention, an exhaust manifold of the beginning to create the type mentioned, with the help of easier Measures the lifespan is significantly increased without being constructive or have to accept functional losses.

The object on which the invention is based is achieved by Exhaust manifold according to the features of claim 1.

The subject of the invention is advantageously further developed through the measures according to claims 2 to 10.

The essence of the invention is in an exhaust manifold made of sheet metal parts the curved, mostly very short inlet pipe even from at least two curved ones arranged side by side Assemble individual pipes, which is preferred are each one-piece individual components.

The basic idea of the invention is the bending stiffness a mostly box-shaped curved one with a large diameter lower known inlet pipe by the wide box-shaped cross-sectional profile of the inlet pipe by at least two narrow pipe profiles arranged side by side is replaced, which in total is much less Moment of resistance and thus reduce the operating load and therefore an increased lifespan or durability an exhaust manifold made of sheet metal is made possible.

The invention is particularly suitable for very short curved ones Pipe guides, according to the state of the art there is a very high section modulus and through a two or more division of the pipe a reduction in Resistance torque to about 25% is conceivable.

The individual tubes are advantageously on the inlet and outlet side inserted in the connection components and by means of fillet weld welded, with individual tubes belonging together one Inlet pipe close together in the plug-in area and otherwise over the rest of the curvature advantageously from each other (slightly) spaced to be different Thermal expansion in the curvature of the individual pipes without mutual To compensate for disability.

The invention is described below using an exemplary embodiment with reference to the accompanying drawing explained, the only figure schematically shows an axially symmetrical Exhaust manifold made of sheet metal parts with three Shows entrances.

The exhaust manifold 1 according to the drawing comprises sheet-shaped inlet pipes 2,3,4 from the respective cylinder head outlet 5,6 or 7 to a common exhaust outlet 8.

In particular, two external inlet pipes 2, 4 are provided, which are curved, and a central rectilinear inlet pipe 3.

The central rectilinear inlet pipe 3 from the middle cylinder is a flat or box-shaped or oval in cross section Single tube in half-shell construction as according to the stand of technology and has an opening on the central top 10 for attaching a lambda probe. On the bottom of the Half shell of the straight single tube 3 is the common exhaust outlet 8, approximately below the opening 10 in Top view of the drawing.

In contrast to the central straight inlet pipe 3 exist the two outer curved inlet pipes 2.4 each of two individual tubes 2a, 2b and 4a, 4b, which are not in Half-shell technology trained, rather one piece Pipe pieces are the ends on one side in the Cylinder head mounting flange 9 and on the other side in the area of the common exhaust outlet 8 in the manifold connection inserted and welded using fillet weld are.

In the embodiment of the drawing are central inlet pipe 3 and manifold integrated.

As can be seen in the embodiment of the drawing, lie the individual tubes 2a, 2b and 4a, 4b in their end insertion regions close together while two belonging Individual pipes slightly over their other course of the curvature are spaced apart to create an unobstructed different thermal expansion in the area of curvature To enable single pipe.

While the individual tubes 2a, 2b and 4a, 4b in the plug area of the cylinder head mounting flange 9 in cross section in essentially round (except for the mutual contact area) are formed, the plug-in areas on the other side in the area of the common exhaust outlet 8 comparatively flat (on the upper side shown) and oval (on the bottom). The cross-sectional change from "Round" to "flat" or "oval" takes place over the length of the Curvature steady.

Claims (10)

1. Exhaust manifold (1) with sheet-metal-formed inlet pipes (2, 3, 4) from the respective cylinder-head exit (5, 6 and 7) through at least one cylinder-head fastening flange (9) of the exhaust manifold to a common exhaust outlet (8), at least one bent inlet pipe (2, 4) being provided, characterized in that each bent inlet pipe (2 and 4) is composed of at least two bent individual pipes (2a, 2b and 4a, 4b) arranged next to one another.
2. Exhaust manifold according to Claim 1, characterized in that each individual pipe is a one-piece component.
3. Exhaust manifold according to Claim 1 or 2, characterized in that the individual pipes have a longitudinally varying cross-sectional shape with a continuous transition.
4. Exhaust manifold according to one of Claims 1 to 3, characterized in that, in each length segment, the individual pipes (2a, 2b and 4a, 4b) have, in total, essentially the same cross-sectional area as the inlet pipe (2 and 4) to be replaced.
5. Exhaust manifold according to one of Claims 1 to 4, characterized in that the individual pipes have an approximately 90° bend.
6. Exhaust manifold according to one of Claims 1 to 5, characterized in that the individual pipes of an inlet pipe lie closely against one another in the region of the cylinder-head fastening flange (9) and in the region of the common exhaust outlet (8) and are otherwise spaced from one another.
7. Exhaust manifold according to Claim 6, characterized in that the individual pipes of an inlet pipe are inserted into the cylinder-head fastening flange (9) and into the central exhaust outlet (8) and welded by means of a fillet weld.
8. Exhaust manifold according to one of Claims 1 to 7, characterized in that two outer bent inlet pipes (2, 4) and one central straight inlet pipe (3) are provided, the outer inlet pipes (2, 4) being composed in each case of two individual pipes.
9. Exhaust manifold according to Claim 8, characterized in that, as seen in a top view, the two outer inlet pipes (2, 4) are arranged axially symmetrically to one another, that is to say, as seen in a top view, are mirror-symmetrical to the longitudinal axis of the central straight inlet pipe (3).
10. Exhaust manifold according to one of Claims 1 to 9, characterized in that the inlet pipes (2, 3, 4) are manufactured by a hydrostatic forming method.

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