Exhaust manifold

The invention relates to an exhaust manifold, in particular an air-gap-insulated exhaust manifold for internal combustion engines.

It's been customary that such exhaust manifold having a manifold, which runs roughly parallel or in longitudinal direction of the newly formed Zylinderflanschs. The data coming from the cylinder flange cylinder tubes are then connected to the edges of openings in the collecting tube, so that the longitudinal direction of the cylinder tubes includes a substantially right angle with the longitudinal direction of the collecting pipe. To improve the flow behavior, it has been tried, the cylinder tubes form slightly curved, so that they open out obliquely into the manifold.

To compound it is possible to provide the binding to the cylinder tube with a collar, which is connected by a weld to the pipe.

This solution has the disadvantage that a high production cost has to be operated by making the holes in the pipes, the fitting of the collar to the pipe and by the weld seams. Since the welded collar stretch direction of the header precludes also occur cracks. The occurrence of gas from the cylinder tube at an angle to the longitudinal axis causes the hot gas applied to the opposite wall, so that, where appropriate, there comes to elevated temperatures, for Lochausbrand. In addition, turbulence is produced by the oblique inflow, which adversely affects the optimum gas velocity.

The invention has for its object to provide an improved view of flow and production technical point of elbow, in particular an exhaust manifold.

To achieve this object, the invention proposes a bend before with the features mentioned in the claim. 1 Further developments of the invention are the subject of dependent claims.

In the aforementioned constellation, ie where the longitudinal direction of the collecting pipe is transverse to the directions of the cylinder flange attached to the cylinder tubes, the cylinder tubes are shaped so that they have in their end region, the direction of the collecting pipe. This curvature, for example by 90 °, can take place in such a way that a gradual deflection of the gas jet is effected. In its end, ie when the gas flows into the manifold, the gases have the same direction as the header, so tHe unilateral local loadings of wall parts occur. The introduction of holes in the wall of the collector tube is omitted, since the cylinder tubes are axially inserted into the open there anyway collecting tube or connected to this.

Since the gas flows are already aligned on exiting from the two cylinder tubes and on entry into the collecting pipe parallel to each other, the problem of the mutual hindrance of the gas streams does not occur anymore. This leads to an improvement in the engine characteristics. It can be caused by cross-sectional selection to ensure that the flow velocity of the gas streams leaving the cylinder tubes is the same.

In development of the invention can be provided that the abutting ends of the combined cylinder pipes along bear a particularly flat surface to each other.

The invention proposes that the section can match the merged ends of the two cylindrical tubes each a semicircle, a semi-oval or other half-mold. For example, if the collection tube has a circular cross-section containing the two cylinder tubes in their end a semi-circular cross-section. In an oval running collecting tube the cross section would accordingly take the form of a semi-oval.

The invention is applicable not only for engines with two cylindrical tubes, but also with several. In three cylinder tubes, it is possible to form all three cylinder tubes so that they are aligned in their end regions parallel to each other and rest against each other. They can then be connected together with the axially aligned collecting tube. In this case it may be provided that are cross-sectional shapes, for example, the two outer cylinder tubes mirrored the same and different from the cross-sectional shape of the central cylindrical tube, also the cross-sectional area of ​​all three cylinder tubes is preferably equal.

However, the invention proposes, in a development that may be provided in a case with three cylinder tubes that initially the first two cylinder pipes are collected in parallel and are connected to an axially aligned intermediate manifold. This intermediate header tube can then with the third cylinder tube in turn are aligned and brought together in parallel, in which case a connection, for example by insertion, takes place with the extending in the same direction collecting tube. In this case obtained in the merging of the intermediate collector pipe to the third cylinder tube between the collecting pipe a twice as large cross-section as the cylinder tube, since it is to receive the flow of gas from two cylinder tubes.

Accordingly, also possible to proceed with the merger of four cylindrical tubes.

According to the invention it can be provided that the intermediate collector pipe is secured by lugs, bulges, projections o. The like. Against slipping, the projections o. The like. Are arranged such that thermal expansions are possible.

The proposed by the invention, parallel alignment of the merged ends of cylinder tubes is particularly important in air-gap-insulated exhaust manifolds applicable in which the gas conducting inner pipe system is arranged within an outer shell, which is connected to the cylinder flange and the collective flange, in particular is welded. In this case, the connection between the cylinder tubes and the collecting tube or the intermediate header tube by simply plugging occur, because a gas leak is no longer required. By appropriate shaping and close fit of the individual parts to one another can be taken to ensure that the leak is small.

Further features, details and advantages will be apparent from the claims, whose wording is made by reference into the description, the following description of a preferred embodiment of the invention and from the drawing. In the figures:<dl id="dl0001"><dt>Fig.1</dt><dd>a schematic side view of an exhaust manifold in which the cylinder flange merges integrally into a collective flange;</dd><dt>FIG. 2</dt><dd>Cross-sections through the arrangement of Figure 1 at two points.</dd><dt>Fig. 3</dt><dd>Cross sections through a similar arrangement with another outer shape;</dd><dt>Fig. 4</dt><dd>a partial longitudinal section through an exhaust manifold with three cylindrical tubes;</dd><dt>Fig. 5</dt><dd>a longitudinal section through the exhaust manifold in FIG. 1.</dd></dl>

The exhaust manifold shown in FIG. 1 includes a flange 1, which is formed in its in FIG. 1, left portion extending over approximately two thirds of the total length than barrel flange 2nd In his right to it subsequent part of the flange 1 is then designed as a collective flange. 3 From the cylinder flange 2 starting three cylinder tubes 4 are fixed to the flange, for example by welding. Each cylindrical tube 4 communicates with an opening in the cylinder flange 2 in conjunction, so that the by passing through the opening of the flange 2 of gas jet is discharged through the corresponding cylindrical tube 4th

The cylinder tubes 4 are attached to the cylinder flange 2 approximately at right angles and extend from there to a quarter arc in a direction that is oblique to the surface of the flange 1 is substantially parallel or slightly.

The first cylindrical tube in Fig. 1 on the far left, the second cylinder tube 4 extends to beyond, where the first two cylinder tubes 4 abut each other and parallel to one another in their end regions. 5 Both end portions 5 of the first cylinder tubes 4 are guided into an intermediate manifold 6, whose axis has the same direction as the end portions 5 of the cylinder tubes 4. It thus occurs no deflection of the two from the two cylinder tubes 4 exiting gas jets in the intermediate collector pipe 6.

The intermediate collector pipe 6 then extends approximately straight on up to the equally coaxially aligned manifold. 7

The third cylinder pipe 4, which also extends bent over a quarter circle is, in its end region parallel to the end portion of the intermediate header pipe 6 and is located with its wall at this. It is lying next to the intermediate header tube 6 inserted into the end of the collection pipe 7, so that both the emerging from the intermediate header pipe 6 gas beam and the gas jet from the cylinder tube 4 run parallel to each other upon entering the manifold 7th The manifold 7 now takes on all gas jets and directs them through the existing on its end sheet 8 to acting as a collective flange part 3 of the flange to.

In an exhaust manifold for an internal combustion engine is the in Fig. 1 to be seen tubing an outer shell, for example in the form of a hood, arranged around the gas-tight welded to the flange 1.

Fig. 2 shows a section at its right half by the arrangement of FIG. 1 along the line BB, that open out to the point at which the end portions 5 of the two cylinder tubes 4 in the provided with a circular cross section intermediate collecting pipe. The cross-section of the two end portions 5 corresponds to a semi-circle, with a plane extending release surface 9 between the two walls which rest tightly against one another. The intermediate collector pipe 6 is applied with a close fit to the two end regions 5 around. Both end portions 5 of the first two cylinder tubes 4 have the same cross-sectional shape and the same cross-sectional size. Because of the two cylinder tubes flows the same amount of gas is achieved in this way an equal speed of the two gas streams as it enters the intermediate collector pipe. 6

Fig. 2 on the left shows a cross section through the arrangement along the line. At this point, the end portion 5 of the third cylinder tube 4 opens together with the end portion of the intermediate header pipe 6 in the manifold 7. Again, is the end portion of the intermediate header tube 6 along to a flat parting surface at the end portion of the third cylinder tube 4th However, the cross section of the intermediate header pipe 6 is approximately twice as large as the cross section of the cylinder tube 4, as from the intermediate header tube 6 exiting the gas stream from the first two cylinder tubes 4th

Fig. 3 shows corresponding views with an exhaust system, in which both the manifold and the intermediate header tube 6 having an oval cross-section.

Fig. 4 shows a longitudinal section through a part of an arrangement in an enlarged scale. The cylinder 2 has a plurality of openings 10 already mentioned, from which emerge the exhaust gases of the engine. In each opening 10 that associated with the motor end of the cylinder tube 4 is inserted and welded. The opposite ends 5 of the two first cylinder tubes 4 are inserted in the intermediate collecting pipe. 6 The two ends 5 of the first two cylinder tubes 4 are neither with each other nor welded to the intermediate header pipe 6 or soldered, so that due to the absence of such a compound, the cost can be further reduced. The first cylinder tube 4 contains nearing its end 5 an outward projection in the form of a bead 11, extending for example over a part of its periphery.

At the opposite end, the intermediate header tube 6 is inserted together with the voltage applied to him third cylinder tube 4 in the collecting pipe. 7 Here, the intermediate header tube 6 includes a bead 11 corresponding to the bead 12. The spacing of the bead 12 of the associated end edge of the intermediate header pipe 6 is chosen so that thermal stresses can be accommodated.

The two beads 11, 12 to prevent slippage of the intermediate collector pipe 7 thermal cycling and vibration.

As shown in FIG. 4 can be seen ranging ends 5 of the cylinder tubes 4 or the end portion of the intermediate header pipe 6 at a relatively short distance in the respective subsequent component into it. The arrangement is such that each gas-conducting pipe element inside is inserted into the subsequent tubular element. The two joined ends 5 of the two first cylinders 4 tubes terminate in the same plane, as well as the third cylinder pipe 4 and the intermediate collecting pipe. 6

Fig. 6 again shows the arrangement of Fig. 1, except terminated at the ends of the flange 1 is shown an outer shell 13, which is along the edge of the flange 1 is welded thereto. The flange 13 may also include holes 14 that match with the corresponding connection holes 15 of the flange first