EP0192995A1 - Exhaust manifold - Google Patents

Abstract

1. Exhaust manifold for a least four cylinder combustion engines with internal combustion comprising outlet pipes (1 to 6) each associated with one cylinder which are brought together groupwise into associated further exhaust pipes (7, 8), which in turn open into a common exhaut pipe (9) leading to an exhaut silencer (10 to 12), wherein all outlet pipes (1 to 6) and likewise the further exhaust pipes (7, 8) respectively each have the same length, characterized in that the total cross-sectional area of the outlet pipes (1 to 6) is larger than the total cross-sectional area of the further exhaust pipes (7, 8), the total cross-sectional area of which is in turn larger than that of the common exhaust pipe (9) ; and in that the outlet pipes (1 to 6) are brought together with nozzle-like narrowed openings into the further exhaust pipes (7, 8) which in turn open with nozzle -like narrowed openings into the common exhaust pipe (9).

Description

The invention relates to an exhaust pipe manifold for at least four-cylinder internal combustion engines with internal combustion, each with a cylinder assigned exhaust pipes, which are grouped together in associated exhaust pipes, which in turn or the like in an exhaust muffler. leading common exhaust pipe open.

Such an exhaust pipe elbow is the subject of DE-B 12 13 670. The outlet pipes initially open into a manifold, which widens in the flow direction from the mouth of the first outlet pipe to the mouth of the last outlet pipe in the flow direction to the cross section of the exhaust pipe. No information is given on the cross section of the common exhaust pipe.

This known arrangement is already unfavorable in terms of flow because different cylinders of the internal combustion engine have exhaust gas paths of different lengths. In addition, in this known exhaust pipe manifold, a comparatively high loss of power of the engine must be accepted if a catalytic converter chamber is arranged in the exhaust gas path for the catalytic decomposition of the exhaust gases.

The object of the invention is now to provide an exhaust pipe elbow which, even when combined with a conventional catalytic converter arrangement, enables approximately the same power yield as is possible in previous exhaust pipe elbows only without the arrangement of a catalytic converter chamber.

This object is achieved in that all the exhaust pipes, like the further exhaust pipes, each have the same length and the total cross section of the exhaust pipes is larger than the total cross section of the further exhaust pipes, the total cross section of which is greater than that of the common exhaust pipe.

Due to the gradual narrowing of the flow cross-section available to the total amount of exhaust gas, a gradual acceleration of the exhaust gas flow is achieved within the exhaust pipe elbow according to the invention with a corresponding gradual pressure reduction. This pressure drop acts in the sense of reducing the flow resistance or pressure opposite the exhaust gas flow, in such a way that the inevitable loss of power caused by the catalytic converter is compensated for. This means that engines whose exhaust gases are catalytically broken down to reduce pollutants can easily achieve the same performance as engines without a catalytic converter in the exhaust line.

The exhaust pipes of the engine or one row of cylinders of the same are expediently combined into two groups, the two associated further exhaust pipes being brought together into the common exhaust pipe assigned to the engine or the row of cylinders.

An embodiment must be regarded as extremely advantageous in terms of flow, in which the outlet pipes are merged with nozzle-like orifices into the further exhaust pipes, especially if the further exhaust pipes are merged with nozzle-like orifices into the common exhaust pipe.

In this arrangement, the exhaust gas flows coming from the exhaust pipes in the respective further exhaust pipe or the exhaust gas flows flowing out from the further exhaust pipes into the common exhaust pipe are combined at an increased speed, which already corresponds to or approximates the mean flow velocity in the further exhaust pipes or in the common exhaust pipe is. This prevents the formation of an increased dynamic pressure in the area of the pipe junctions. In addition, particularly good mixing of the individual merged exhaust gas streams is achieved with one another.

With regard to the pipe cross sections, it is advantageous if the total cross section of a group of the exhaust pipes is approximately 1.5 to 2.5 times the cross section of the further exhaust pipe assigned to this group and the cross section of the common exhaust pipe is approximately one third to three quarters of the total cross section of the further exhaust pipes opening therein .

In the case of six exhaust pipes, which are brought together in two groups in two exhaust pipes, an arrangement is particularly preferred in which the exhaust pipes have a total of about 1.6 times the total cross section of the exhaust pipes and the latter together have about 2 times the cross section of the common exhaust pipe. A favorable torque curve of the engine can thus be achieved, in particular even at lower speeds.

The outlet pipes should preferably have approximately twice the length of the exhaust gas pipes. The length of the common exhaust pipe can be about the length of the further leading exhaust pipes. If necessary, however, the common exhaust pipe can also be longer.

A shorter dimension of the common exhaust pipe is fundamentally also possible, however, under certain circumstances a relatively small mixture of the exhaust gas flows coming from the further exhaust pipes has to be accepted.

In the case of six outlet pipes which are brought together in two groups in two further exhaust pipes, the ratio of the length of an outlet pipe to the length of a further exhaust pipe is particularly preferably approximately 6: 2.5.

The ratio of the lengths of the outgoing exhaust pipes and the common exhaust pipe can be approximately 5: 4.

A particular advantage of the invention lies in the fact that the common exhaust pipe can accommodate a lambda probe, as is customary for controlling the engine in exhaust gas purification by means of catalysts. In this way, the lambda probe is arranged in an area of the exhaust system with a small cross-section and is acted upon by the entire exhaust gases of the engine or a row of cylinders. It is therefore reliably prevented that part of the exhaust gas flow or the exhaust gases of individual cylinders can bypass the lambda probe.

In this context, an arrangement is particularly expedient in which the lambda probe is arranged in the region of the mouth of the common exhaust pipe in a catalyst chamber. Because here the exhaust gases have reached a particularly good degree of mixing. In addition, the high Flow rate of the exhaust gases that a constant gas exchange takes place in the vicinity of the lambda probe.

In addition, the arrangement of the lambda probe in front of the catalyst chamber takes into account the fact that higher exhaust gas temperatures are advantageous for the lambda probe than those prevailing in the downstream chamber.

In view of the high stability of the exhaust pipe elbow, it is expedient if the exhaust pipe elbow is designed as a sheet metal part or is composed of sheet metal parts. Compared to a basically possible design as a casting, a higher resistance to mechanical vibrations is achieved. In addition, the dimensions of sheet metal parts can be changed comparatively easily, so that, if necessary, the exhaust system can be adjusted without excessive costs if the respective engine is changed.

The merging of two exhaust pipes into one exhaust pipe is preferably carried out in such a way that one exhaust pipe passes continuously through the pipe junction into the downstream exhaust pipe and the other exhaust pipe is connected laterally at an angle by arranging an opening which is drawn around half the circumference and on the first pipe the pipe wall adjoining this pipe on the upstream side of the opening in the axial direction of this pipe is pressed in to form a surface which is oblique to the pipe axis, the layout of which resembles an ellipse half, and by the other pipe being blunt on one circumferential half and the other circumferential half End cut obliquely to the tube axis is welded to the first tube, the obliquely cut edge on the elliptical edge edge and on the edge extending this edge

opening edges and the bluntly cut edge is welded to the opening edge opposite the inclined surface.

The cutting plane of the oblique cut and the axis of the other tube should form approximately the same angle as the oblique surface and the axis of the one tube, so that the tube axes form a V that is approximately symmetrical to the oblique surface.

The design described enables a particularly high stability due to the one-piece tube arranged continuously. At the same time, the design of the inclined surface together with the connection shown of the other tube ensures the formation of the nozzle-shaped constrictions for the exhaust gas flows which merge into one another in a structurally particularly simple manner.

When the ends of three pipes are brought together in a further pipe, a funnel part is preferably arranged, one end of which has a cross section corresponding to the further pipe and the other end of which has a cloverleaf-like cross section. The ends of the three tubes arranged in bundles next to one another are cut off obliquely on the circumferential side facing away from the other two pipes and inserted with the obliquely cut off areas into the funnel in such a way that the funnel covers the obliquely cut off circumferential sides, i.e. the funnel replaces the cut off wall part of the Pipe ends. Here, too, the nozzle-shaped constriction is again formed, because the wall parts of the pipe ends that extend into the funnel together with form the cone-like tubular elements of the opposite wall part of the funnel.

• Fig. 1. in schematisierter Form einen erfindungsgemäßen Abgasrohrkrümmer für einen Sechszylinder-Reihenmotor,
• _Fig. 2 einen entsprechenden Abgasrohrkrümmer für einen Vierzylinder-Reihenmotor,
• Fig. 3 eine Draufsicht auf die Zusammenführung zweier Abgasrohre,
• _Fig. 4 eine Draufsicht auf das in Fig. 3 untere Abgasrohr entsprechend dem Pfeil IV in Fig. 3,
• Fig. 5 eine Zusammenführung dreier Rohre und
• Fig. 6 eine Ansicht des zur Zusammenführung der drei Rohre dienenden Trichters entsprechend dem Pfeil VI in Fig. 5.

Otherwise, with regard to preferred features of the invention, reference is made to the subclaims and the following description of the invention with reference to the drawing, in which particularly preferred embodiments are shown. Show

• 1. in schematic form an exhaust pipe elbow according to the invention for a six-cylinder in-line engine,
• _F ig. 2 a corresponding exhaust pipe elbow for a four-cylinder in-line engine,
• 3 is a plan view of the merging of two exhaust pipes,
• _F ig. 4 shows a top view of the lower exhaust pipe in FIG. 3 according to arrow IV in FIG. 3,
• Fig. 5 is a merge of three pipes and
• 6 is a view of the funnel used to bring the three tubes together in accordance with arrow VI in FIG. 5.

1, a total of six exhaust pipes 1 to 6 are arranged on the exhaust side of a six-cylinder in-line engine, not shown, each of which is assigned to a cylinder. These exhaust pipes 1 to 6 have the same length as possible and are combined into two groups, such that the exhaust pipes 1 to 3 are brought together in a further exhaust pipe 7 and the exhaust pipes 4 to 6 are brought together in a further exhaust pipe 8. The total cross section of the exhaust pipes 1 to 3 or 4 to 6 of each group is approximately twice as large as the cross section of the respectively assigned exhaust pipe 7 or 8.

The further exhaust pipes 7 and 8 are in turn merged into a common exhaust pipe 9, the cross section of which corresponds approximately to the cross section of each of the further exhaust pipes 7 and 8, i.e. the total cross section of the further exhaust pipes 7 and 8 is approximately twice as large as the cross section of the common exhaust pipe 9. In FIG. 1, various options are now shown for the elements of the exhaust line connected to the common exhaust pipe 9.

Thus, the common exhaust pipe 9 can bifurcate in its further course and open into a front silencer 10, which is followed by a rear silencer 11, front silencer 10 and rear silencer 11 being connected to one another via double pipes and the rear silencer being opened to the atmosphere via a double pipe. This embodiment is shown in the upper right section of FIG. 1.

Instead, the common exhaust pipe 9 can also open into the front silencer 10 ', which in turn is connected to the rear silencer 11 ¹ via a simple pipe, which in this case is connected to the atmosphere via a simple exhaust tail pipe.

In view of existing or future environmental protection regulations, it is desirable to remove the pollutants in the exhaust gases by catalytic decomposition. In this case, a catalytic converter chamber 12 is arranged instead of the front silencer 10 or 10 ¹ , in which the exhaust gases flow through a catalytic converter and, at least in part, are broken down into their elementary components. The catalyst chamber 12 is then in turn followed by a rear silencer 11 ″, which in turn is connected to the atmosphere via an end pipe.

In principle, instead of the arrangement shown at the bottom right in FIG. 1, in which the common exhaust pipe 9 opens into the catalyst chamber 12 without being forked, it is also possible to provide a fork of the common exhaust pipe 9, so that the fork pipe sections are divided into separate catalyst chambers, which in one common housing can be arranged, open. In the latter case, the two catalyst chambers connected in parallel are expediently connected via a double pipe to a common rear silencer or to separate rear silencers, which in turn can be accommodated in a common housing.

For catalytic converter operation, it is expedient for the engine to be controlled by means of a lambda probe 13, in particular with regard to the mixing ratio of the supplied fuel with air and the ignition times. In the arrangement according to the invention, the lambda probe 13 is arranged on a corresponding bore in the common exhaust pipe 9. This ensures that the lambda probe 13 is acted upon by the exhaust gases of all cylinders. This is all the more so as a corresponding acceleration of the exhaust gas flow occurs due to the overall cross-section of the exhaust line decreasing from the exhaust pipes 1 to 6 via the further exhaust pipes 7 and 8 and the common exhaust pipe 9, and the increased flow speeds thus promote intensive mixing of the exhaust gases .

In addition, it is advantageous that the lambda probe 13 is only a relatively short distance from the engine along the flow path of the exhaust gases and is accordingly acted upon by exhaust gases of relatively high temperature, as is favorable for optimal functioning of the lambda probe 13.

In contrast, the catalytic converter or the catalytic converter chamber 12 accommodating it can be arranged at a greater distance from the engine in order to avoid the catalytic converter being overheated when the engine is operating at full load, in particular when operating at full load and at low speed.

The invention thus enables optimal placement of both the lambda probe 13 and the catalyst. In addition, the back pressure generated by the catalytic converter due to its throttling effect in the exhaust line is largely compensated by the fact that - as already mentioned - the pressure of the exhaust gases corresponding to the narrowing of the cross-section of the exhaust line from the exhaust pipes 1 to 6 via the exhaust pipes 7 and 8 and the common exhaust pipe 9 gradually decreases, with a corresponding increase in flow velocity.

The embodiments shown in FIG. 2 correspond to the embodiments according to FIG. 1 in all essential points. In Fig. 2 only the case of a four-cylinder in-line engine is shown, in which according to the number of cylinders only four exhaust pipes 1 to 4 are to be arranged. It is spatially easily possible to take into account the firing order of the cylinders of the engine, for example by exhaust pipes 1 and 4 or exhaust pipes 2 and 3 each opening into one of the exhaust pipes 7 and 8, for example if the first, fourth, second and third cylinders are fired in succession. Otherwise, the explanations and explanations for FIG. 1 apply analogously to FIG. 2.

In Figures 1 and 2 is shown by dashed lines, arranged within the tubes wall parts 14 that the mouth areas of the exhaust pipes 1 to 6 and 'the mouth areas of the further exhaust pipes 7 and 8 according to a preferred embodiment of the invention in the exhaust gas flow direction in the manner of a nozzle can or should be conically narrowed.

In the following FIGS. 3 to 6, structurally preferred options are now shown for realizing the corresponding nozzle-shaped mouth regions in the region of the pipe junctions using sheet metal parts.

3 shows the merging of two exhaust pipes 107 and 108. The exhaust pipe 107 corresponds, for example, to a section of the outgoing exhaust pipe 7 in FIGS. 1 or 2, while the exhaust pipe 108 with its area 108 'is a section of the outgoing exhaust pipe 8 in FIGS. 1 and 2 and with its area 108 "is a section of the common area Exhaust pipe 9 forms in Figures 1 and 2.

The pipe 108, which is made in one piece by bringing the pipes 107 and 108 together, has between its regions 108 'and 108 "an opening 109 which extends over approximately half the circumference. Following the opening 109, the circumferential wall of the pipe is on the opposite side to the exhaust gas flow direction Side of the opening 109 pressed inward to form an inclined surface 110, which in the example shown forms an angle of approximately 20 ° with the tube axis. In a plan view, the inclined surface 110 has approximately the shape of an ellipse half.

The merged with the pipe 108 end of the pipe 107 is cut obliquely on its side facing the pipe 108, approximately at an angle of likewise 20 °, to the pipe axis, such that an edge 111 is formed, the contour of which when viewed in the direction of the arrow VI has approximately the same shape as the edge of the inclined surface 110 and the edges 109 "of the opening 109 which continue this edge. On the circumferential half opposite the edge 111, the end of the tube 107 is bluntly cut off to form an edge 112 which adjoins the edge 109 ' opening 109 fits.

To connect the pipes 107 and 108, the edges 111 and 112 of the pipe 107 are welded to the edges of the inclined surface 110 and the adjoining opening edges 109 "and 109 '. The inclined surface 110 thus narrows both of the above-mentioned in the area where pipes 107 and 108 are brought together Pipes in the same way.

In addition to being easy to manufacture, the construction shown is characterized by high stability because one of the tubes is made in one piece.

5 and 6, a funnel 100 is arranged to bring together three pipes, the downstream end of which (on the right in FIG. 5) has a cross section corresponding to the exhaust gas line, not shown below. At the other end, the funnel widens with a cloverleaf-like cross section, such that the cloverleaf cross section at the end of the funnel corresponds to the cross section of three bundled tubes, of which only tubes 101 and 102 are visible in FIG. 5. Each of these tubes is cut obliquely at its ends, similar to tube 107 in FIG. 3, on the opposite side from the other two tubes Perimeter. This allows the tubes 101 and 102 to be inserted correspondingly far into the funnel 100 and welded to the same and to one another. The funnel thus covers the respective obliquely cut circumferential side of the tubes 101 and 102. At the same time, the wall areas of the tubes 101 and 102 protruding into the funnel 100 together with the associated “cloverleaf” segment of the funnel 100 each form a nozzle that narrows in the direction of flow, see above that the exhaust gas flow coming from each of the pipes 101 and 102 is correspondingly accelerated before being combined with the exhaust gas flows of the other pipes.

In the example in FIG. 5, a fastening flange is arranged on the funnel 100. Instead, other fastening elements can optionally also be used for connection to further exhaust pipes. If necessary, a part of the outgoing exhaust pipe can also be connected directly to the funnel 100. Otherwise, articulated connections or bellows connections may also be arranged if the mobility of the exhaust parts relative to one another is to be ensured.

In a six-cylinder engine with a displacement of approximately 2500 cm ³ , an exhaust pipe elbow according to the invention has the following dimensions, for example:

Claims (16)

1. Exhaust pipe elbow for at least four-cylinder internal combustion engines with internal combustion, each with a cylinder assigned exhaust pipes (1 to 6), which are grouped together in assigned further exhaust pipes (7,8), which in turn lead to a common exhaust gas silencer (10 to 12) Exhaust pipe (9) open,
characterized,
that all outlet pipes (1 to 6) as well as the further exhaust pipes (7,8) each have the same length and that the total cross section of the outlet pipes (1 to 6) is larger than the total cross section of the further exhaust pipes (7,8), their total cross section is larger than that of the common exhaust pipe (9). 2. Exhaust manifold according to claim 1, characterized in that the exhaust pipes (1 to 6) at least one row of cylinders of the engine are combined into two groups and the two associated further exhaust pipes (7,8) are merged into the common exhaust pipe (9) assigned to the row of cylinders are. 3. Exhaust pipe elbow according to one of claims 1 or 2, characterized in that the outlet pipes (1 to 6) are merged with nozzle-like narrowed mouths in the further exhaust pipes (7,8). 4. Exhaust pipe elbow according to one of claims 1 to 3, characterized in that the further exhaust pipes (7,8) are merged with nozzle-like narrowed mouths in the common exhaust pipe (9). 5. Exhaust pipe elbow according to one of claims 1 to 4, characterized in that the total cross section of a group of exhaust pipes (1 to 3, 4 to 6; 1 and 4, 2 and 3) about 1.5 to 2.5 times the cross section of the further exhaust pipe (7,8) assigned to this group and the cross section of the common exhaust pipe (9) is approximately one third to three quarters of the total cross section of the further exhaust pipes (7,8) opening therein. 6. Exhaust pipe elbow according to one of claims 1 to 5, characterized in that with six outlet pipes (1 to 6), which are brought together in two groups (1 to 3, 4 to 6) in two further exhaust pipes (7,8) Outlet pipes (1 to 6) have a total of approximately 1.6 times the total cross section of the exhaust gas pipes (7,8) and the latter together have approximately 2 times the cross section of the common exhaust pipe (9). 7.-exhaust pipe elbow according to one of claims 1 to 6, characterized in that the outlet pipes (1 to 6) at least about twice the length of the further exhaust pipes (7,8), measured from the mouth of the outlet pipes into the respective further exhaust pipe up to have its mouth in the common exhaust pipe. 8. Exhaust pipe elbow according to one of claims 1 to 7, characterized in that the further exhaust pipes (7,8) have comparable length as the common exhaust pipe (9). 9. _A gas pipe elbow according to one of claims 1 to 8, characterized in that with six outlet pipes (1 to 6) which are brought together in two groups (1 to 3, 4 to 6) in two further exhaust pipes (7, 8), the ratio of the length of an outlet pipe to the length of a further exhaust pipe is approximately 6: 2.5. 10. Exhaust pipe elbow according to claim 9, characterized in that the ratio of the lengths of the secondary exhaust pipes (7,8) and the common exhaust pipe (9) is 5: 4. 11. Exhaust pipe elbow according to one of claims 1 to 10, characterized in that the common exhaust pipe (9) receives a lambda probe (13) and the exhaust gases in a chamber (12) with a catalyst for catalytic transfer of the exhaust gases. 12. Exhaust pipe elbow according to claim 11, characterized in that the lambda probe is arranged in the region of the mouth of the common exhaust pipe (9) in the exhaust silencer or a catalyst chamber. 13. Exhaust pipe elbow according to one of claims 1 to "2, characterized in that the common exhaust pipe (9), the further exhaust pipe (7, 8) opening therein and the outlet pipe E (1 to 6) associated therewith are formed as a sheet metal part or sheet metal parts are. 14. _A gas pipe elbow, in particular according to claim 13, characterized in that for merging two - further - exhaust pipes (107, 108), the one exhaust pipe (108) running in one piece into the downstream - common - exhaust pipe passes over and the other - Further - exhaust pipe (107) is connected laterally at an angle by arranging an opening drawn around half the circumference on the first pipe (108) and connecting the pipe wall in the axial direction of this pipe on one side of the opening, forming an oblique surface to the pipe axis , the layout of which resembles an ellipse half, is pressed in, and the other tube (107) is welded to the first tube (108) with its end that is blunt on one circumferential half and on the other circumferential half obliquely to the tube axis, the obliquely cut edge is welded to the elliptical bevel edge and to the opening edges that extend this edge and the bluntly cut edge is welded to the opening edge opposite the bevel. 15. Exhaust pipe elbow according to claim 14, characterized in that the cutting plane of the oblique cut and the axis of the other tube (107) form an approximately same angle as the inclined surface and the axis of the one tube (108). 16. Exhaust pipe elbow, in particular according to one of claims 13 to 15, characterized in that for merging the ends of three pipes (101 to 103) in a - further - pipe a funnel part (100), one end of which corresponds to the further pipe Cross-section and the other end of which has a cloverleaf-like cross-section, is arranged and the ends of the three tubes (101 to 103) arranged in bundles next to one another are cut obliquely on the circumferential side facing away from the other two tubes, and with the obliquely cut-off areas in the funnel (100) in such a way are inserted that the funnel (100) covers the obliquely cut peripheral sides.

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