Exhaust manifold

The invention is based on an air-gap-insulated exhaust manifold for Internal combustion engines according to the preamble of Claim first

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

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

This solution has the disadvantage that a high production effort by Making the holes in the pipes, the fitting of the collar on the must be tube and operated by the welds. Since the welded Collar the expansion direction of the header precludes also occur cracks. The occurrence of gas from the cylinder tube at an angle from the longitudinal axis causes the hot Gas acts on the opposite wall, so that there increased Temperatures, optionally comes to Lochausbrand. also is the oblique inflow turbulence generated, is detrimental to the optimum gas velocity.

There is already an air gap insulated exhaust manifold having the features known of the first part of claim 1 (DE-A-42 26 171).

Furthermore, it is known, in internal combustion engines, the ends of self-supporting exhaust pipes in parallel and adjacent to one another to arrange. This is to ensure that each of the Cylinder tubes originating gas pulses at different times in a continuing exhaust pipe lead (WO 92-03639).

The invention is based on the object, a view of flow and manufacture technically improved exhaust manifold to create.

To achieve this object, the invention proposes a manifold with the in claim 1 mentioned before features. Developments of the invention are the subject of subclaims.

Thus, the invention proposes that in a case with three cylinder tubes is provided that initially the first two cylinder tubes together in parallel are and with an axially oriented intermediate collecting pipe get connected. This intermediate manifold may then the third cylinder tube again aligned and merged in parallel are, in which case a connection, for example by insertion, carried out with the running in the same direction collecting tube. In this case obtained in the merging of the intermediate collector pipe a double with the third cylinder tube between the collecting pipe so large cross-section as the cylinder tube, since there the gas flow is scheduled to start from two cylinder tubes.

Accordingly, even with the merger of four or more Cylinder tubes to proceed.

In the aforementioned constellation, that is where the longitudinal direction of the Collector pipe of the mounted transverse to the directions on the cylinder flange Cylinder tubes is, the first two cylinder tubes are formed to its end in the direction of the intermediate collector pipe exhibit. This curvature, for example by 90 °, can so take place in that a gradual deflection of the gas jet is effected. In its end region, ie, if the gas flows to the intermediate collecting pipe, the gases have the same direction as the intermediate collector pipe, so that no unilateral local loadings of wall parts occur. The incorporation of holes in the wall of the intermediate collection tube does not apply because the first two cylinder tubes axially into there anyway plugged open intermediate collecting tube or connected to this will.

As the gas flows upon exiting from the first two cylinder tubes and already parallel to each other upon entry into the intermediate header tube are aligned, also occurs the problem of mutual hindrance of the gas streams is no longer on. This leads to an improvement in the engine characteristics. It can be caused by cross-section selection for that the flow speed of the two gas streams leaving the cylinder tubes is the same. The same applies for the third and any other cylinder tubes.

In development of the invention it can be provided that the mutually adjacent merged ends of the cylinder pipes along a particularly flat surface abut each other.

The invention proposes that the cross section through the merged Ends of the first two cylinder tubes each having a semi-circle, may correspond to a half-oval or other half-mold. If For example, the intermediate header tube has a circular cross-section which included the first two cylinder tubes in its end a semi-circular cross-section. In an oval running intermediate manifold the cross-section would accordingly the form of a have semi-oval.

According to the invention it can be provided that the intermediate collecting pipes secured by approaches, bulges or protrusions against slipping are, these being arranged so that thermal expansions are still possible.

The proposed by the invention, parallel alignment of the merged Ends of cylindrical tubes is particularly important in air-gap-insulated Exhaust manifolds applicable, in which the gas-carrying inner pipe system is disposed within an outer shell, with the cylinder flange and the collective flange connected, in particular welded, is. In this case, the connection between the cylinder tubes, the manifold and the intermediate headers by simply Plug take place because a gas-tightness is not required. By appropriate shaping and close fit of the individual parts each other can be ensured that the leakage is kept small becomes.

Further features, details and advantages will be apparent from the claims, whose wording by reference into the description is made, the following description of a preferred Embodiment of the invention and from the drawing. In the figures:<dl tsize="6"><dt>Fig. 1</dt><dd>a schematic side view of an exhaust manifold, wherein which the cylinder flange integrally into a collective flange merges;</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 External 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 in his in Fig. 1 left portion extending over approximately two thirds of the total length extends, is formed as a cylinder flange 2nd In his to it right subsequent Part is then formed as a collective flange 3 of flange. 1 From the cylinder flange 2 starting three cylinder tubes 4 attached 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 opening of the Flange 2 by passing the gas jet through the appropriate is derived cylinder tube. 4

The cylinder tubes 4 are the cylinder flange 2 as under mounted at right angles and extend from there to a quarter arc in a direction substantially parallel or slightly oblique to the surface of the flange 1 runs.

The first cylindrical tube in Fig. 1 on the far left, extends to above the second cylinder tube 4 also, the two first cylindrical tubes 4 abut each other and in their End regions 5 parallel to each other. Both end portions 5 of the first cylinder tubes 4 are in an intermediate manifold 6 ushered whose axis the same direction having as the end portions 5 of the cylinder tubes 4. It occurs So in the intermediate collector pipe 6 no deflection of the two from the two cylinder tubes at 4 exiting gas jets.

The intermediate collector pipe 6 then continues as straight to which also coaxially aligned collector pipe . 7

The third cylinder tube 4, which is also a quarter-circle is curved, is parallel in its end to the end portion of the intermediate collector pipe 6 and is with its wall at this on. It is next to the intermediate manifold 6 lying inserted into the end of the collection pipe 7 so that both of exiting from the intermediate header pipe 6 gas jet and the gas jet from the cylinder tube 4 when entering 7 in the collecting pipe parallel to each other. The Manifold 7 now takes on all gas jets and directs them over the present at its end sheet 8 to as Collective flange acting part 3 of the flange to.

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

FIG. 2 shows a section in its right half by the Arrangement of FIG. 1 along the line BB, ie in the Location at which the end portions 5 of the two cylinder tubes 4 in which is provided with a circular cross section intermediate manifold open out. The cross-section of the two end portions 5 corresponds to a semi-circle, with a flat running Separating surface between the two walls close to one another rest. The intermediate collector pipe 6 is a close fit applied to the two end regions 5 around. Both end portions 5 of the first cylinder tubes 4 have the same Cross-sectional shape and the same cross-sectional size. Because of two cylinder tubes flows the same amount of gas is in this way an equal speed of the two Gas flows reached upon entering the intermediate collector pipe. 6

Fig. 2 on the left shows a cross section through the arrangement along the line AA. At this point opens the tail section 5 the third cylinder tube 4 together with the end region of the Between collector pipe 6 in the manifold 7. Again, is the End portion of the intermediate collector pipe 6 along a plane Separating surface at the end portion of the third cylinder tube 4 at. However, the cross section of the intermediate header pipe 6 is approximately twice as large as the cross section of the cylinder tube 4, since from the intermediate header pipe 6, the gas stream from the two first cylindrical tubes 4 emerges.

Fig. 3 shows corresponding views with an exhaust system, wherein both the collecting pipe and the intermediate collecting pipe 6 has an oval cross section.

Fig. 4 shows a longitudinal section through part of a Arrangement in an enlarged scale. The cylinder 2 has a plurality of openings 10 already mentioned, from which the exhaust of the engine leak. In each aperture 10 is associated with the motor end of a cylinder tube 4 inserted and welded. The opposite ends 5 the first two cylinder tubes 4 are in the intermediate collector pipe 6 inserted. The two ends 5 of the first two Cylinder tubes 4 are each other or any of the intermediate collector pipe 6 welded or soldered, so that due to the Elimination of such a compound further reduced costs can be. The first cylinder tube 4 contains just before its end portion 5 has an outwardly directed projection in Form of a bead 11, for example, about a Part of its circumference extends.

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

The two beads 11, 12 are slipping of the intermediate collector pipe 7 thermal cycling and prevent vibrations.

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

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