EP1457647B1 - Exhaust system for an internal combustion engine - Google Patents

Abstract

An exhaust for a combustion engine comprises a manifold (1,1') with inlet tubes (6,6',8,8') into a combining unit (9) having an outlet to further parts, especially a catalyst housing (3,3'). The combining unit comprises a single piece housing of rigid material.

Description

The present invention relates to an exhaust system of an internal combustion engine having at least one exhaust manifold with a plurality of inlet pipes for connection to exhaust ports of the internal combustion engine and a collector for combining the intake pipes, having an outlet opening which is connected to subsequent elements of the exhaust system, including a catalyst housing, wherein the collecting means is designed as a one-piece collector housing.

The exiting from the outlets of an internal combustion engine exhaust gases are usually summarized via exhaust manifold in one or more exhaust main lines. For this purpose, the exhaust manifold has a plurality of inlet pipes and a collecting device with an outlet opening, which is connected to a further exhaust pipe or directly to an exhaust gas catalytic converter. The exhaust system in the exhaust manifold has significance for the exhaust back pressure. In addition to the requirement to design this optimally, but it is also important that the time required for engine control, so-called lambda probe is flown in a suitable manner. A goal here is to flow as evenly as possible on the lambda probe with the individual exhaust gas streams of all intake pipes in order to have the same conditions for each cylinder of the internal combustion engine. In addition, the flow of a subsequent catalyst should be as uniform as possible.

An exhaust system of the aforementioned type is known from US-A1-6,082,103. In EP-A2-1 247 954, the inlet pipes are brought together in the inlet funnel of the catalyst housing.

EP-A2-733 788 discloses a pipe junction of two exhaust pipes through a manifold. A collector housing is not disclosed here. The same applies to DE-U-296 17 304, which shows a pipe junction of four exhaust pipes.

The present invention has for its object to improve an exhaust system of the type mentioned. In particular, an advantageous lambda and Katalysatoranströmung should be achieved. In addition, the production should be as simple as possible and the stability of the exhaust system as high as possible.

This object is solved by the features of claim 1.
By forming the collecting device as a separate collector housing, an advantageous construction of the exhaust system can be achieved. In particular, the production can be simplified because the one-piece collector housing, for example, by hydroforming including necklaces for the pipe connection is inexpensive to produce and additionally only simple pipes are needed. In this case, the collector housing at least two, preferably three openings for connecting inlet pipes and an outlet opening, via which the collector housing is connected to subsequent parts of the exhaust systems.

Also advantageous is the inventive combination of a collector housing made of rigid material with inlet pipes of relatively flexible material which allow a length compensation due to different thermal expansion. The inlet pipes can be made relatively short, so that the collector housing can be brought very close to the exhaust gas outlets of the internal combustion engine. This saves space and increases advantageously the exhaust gas temperature in a subsequent catalyst.

It is also particularly preferred if the collector housing additionally has an opening for inserting a lambda probe. The lambda probe is thus located in a space in which the exhaust gas streams of all exhaust pipes of the exhaust system meet, so that a largely uniform flow of the lambda probe can be achieved by the different exhaust gas streams. In addition, this allows the redesign of the exhaust gas flow for the Katalysatoranströmung after the lambda probe done, so separated from the Lambdaanströmung. Through this separation, both streams can be optimized for each.

According to a further embodiment of the invention, an outlet pipe is connected to the outlet opening of the collector housing, which is designed in particular as a catalyst inlet pipe. The outlet tube thus fulfills a dual function, and good catalyst inflow can be achieved.

It is particularly preferred if the Katalysatoranströmrohr is guided to close to the catalyst, wherein the catalyst housing is connected via a Katalysatoranströmrohr surrounding, in particular funnel-shaped tube directly to the collector housing. This results in a double-walled exhaust system with an annular space formed between the outlet tube of the collector housing and inlet funnel of the catalyst, which is only connected in shunt to the exhaust gas flow. This space therefore acts as a thermal insulation for the exhaust stream, whereby the exhaust gas temperature in the catalyst can be increased.

The openings in the collector housing are at least partially punched out according to a further embodiment of the invention. As a result, the production can be simplified and cheapened.

According to a further embodiment of the invention, the inlet pipes open into the collector housing such that the exhaust gas flow directions of all exhaust gas streams converge in a collection point. By this configuration the exhaust system, the exhaust gas flow is optimized. In particular, this results in the possibility of arranging the lambda probe with its probe tip in a point which is at least substantially uniformly flowed by the individual exhaust gas streams of all connected inlet pipes. Thereby, the engine control can be improved in the desired manner.

The inlet pipes preferably lead into the collector housing such that the exhaust gas flow directions are each inclined to a plane perpendicular to the exhaust gas flow direction in the outlet opening, such that the exhaust gas flow directions of the inlet pipes point to the same side of this plane as the exhaust gas flow direction in the outlet opening. The outflow of the exhaust gas through the outlet opening is thereby improved and the exhaust backpressure can be reduced.

A preferred arrangement of the lambda probe is on the side facing away from the outlet opening of the collector housing. On the one hand, this makes it possible to achieve the arrangement of the probe tip in the collection point of the exhaust gas flows, and on the other hand, the exhaust gas flow is relatively little affected. In addition, this is structurally advantageous.

The inlet pipes open in particular into the collector housing in such a way that the collection point of the exhaust gas streams is located inside the collector housing. As a result of this refinement, the lambda inflow takes place within the collector housing and before the realignment of the exhaust gas flow for the catalyst outflow. This separation further improves the flow of the lambda probe and the catalyst.

Preferably, the collector housing has molded connecting pieces for the inlet pipes and / or the outlet pipe. This embodiment has a constructive advantages and on the other hand, the assembly of the exhaust system is simplified. Above all, this embodiment enables a welding of the collector housing with the inlet pipes and the outlet pipe on the outside. An intrusion of weld beads into the interior of the exhaust system and the associated problems, in particular the risk of deterioration of the catalyst, can be avoided.

According to a further embodiment of the invention, the collector housing is at least partially formed mirror-symmetrically to a plane perpendicular to the connecting line of the exhaust gas outlets of the internal combustion engine. The exhaust gas flow and in particular the flow of the lambda probe can thereby be further uniformed.

According to a particularly preferred embodiment of the invention, the inlet pipes and / or the lambda probe are arranged and formed mirror-symmetrically. On the one hand, the exhaust gas flow can be evened out even further hereby. On the other hand, this embodiment has the advantage that the components of the exhaust system can be standardized. In particular, the same components can be used for different exhaust strands. Thus, for example, in exhaust systems with two exhaust manifolds according to the invention, these may be at least partially identical in design, despite the normally different installation situation at the various outlets of the internal combustion engine. As a result, costs can be saved and storage can be simplified.

The inlet pipes are preferably formed at least in sections with an oval cross-section. As a result, a higher deformability of the inlet pipes is achieved, by which a better length compensation can take place with different thermal expansion of the pipes.

A better deformability for length compensation also results when the inlet pipes are made according to a further embodiment of the invention by hydroforming.

Fig. 1

eine Ansicht eines Teils einer erfindungsgemäßen Abgasanlage aus einer ersten Richtung,

Fig. 2

eine Ansicht des Teils von Fig. 1 aus einer hierzu um 90° verdrehten Richtung,

Fig. 3

ein Detail von Fig. 1 in vergrößerter und teilweise geschnittener Darstellung,

Fig. 4

eine Schnittansicht gemäß Schnittlinie B-B in Fig. 1,

Fig. 5

eine Ansicht eines Sammlergehäuses einer erfindungsgemäßen Abgasanlage und

Fig. 6

eine Ansicht eines anderen, mit einem Anströmrohr einstückig ausgebildeten Sammlergehäuses einer erfindungsgemäßen Abgasanlage.

Embodiments of the invention are illustrated in the drawings and will be described below. Shown schematically in each case:

Fig. 1

3 is a view of part of an exhaust system according to the invention from a first direction,

Fig. 2

1 is a view of the part of FIG. 1 from a direction rotated by 90 °,

Fig. 3

a detail of Fig. 1 in an enlarged and partially sectioned view,

Fig. 4

a sectional view along section line BB in Fig. 1,

Fig. 5

a view of a collector housing an exhaust system according to the invention and

Fig. 6

a view of another integrally formed with a flow pipe header housing of an exhaust system according to the invention.

The exhaust system partially shown in Figures 1 and 2 comprises two three-jet exhaust manifold 1, 1 ', the inlet side with a motor flange 2, 2' and the outlet side via inlet funnel 3a, 3a 'with a catalyst housing 3, 3' are connected. To the catalyst housing 3, 3 'in each case includes a continuing exhaust pipe 4, 4', which in turn is connected in each case with a flange 5, 5 'for connection to a further exhaust pipe.

The exhaust manifolds 1, 1 'each have three inlet pipes 6, 6', 7, 7 'and 8, 8' of relatively soft or flexible material, each disposed on the exhaust gas inlet side in an opening of the associated engine flange 2, 2 'and exhaust outlet side with a collector housing 9, 9 'are connected. The collector housing 9, 9 'has walls, in which connecting pieces 10, 10', 11, 11 'and 12, 12' are formed, and is formed of relatively rigid material.

As can be seen in particular in Figures 3 to 6, the walls of the collector housing 9, 9 'enclose a collecting space 13, in which the exhaust gas streams from the inlet pipes 6, 6', 7, 7 ', 8, 8' out. The exhaust gas flow directions I, II, III are directed to a common collection point 14 in the interior of the collecting space 13. The walls of the collector housing 9, 9 'also have a recess 15, in which a lambda probe 16, 16' is inserted. Namely, the lambda probe 16, 16 'inserted into the recess 15 such that its probe tip 17 is in the region of the collection point 14.

Regardless of which cylinder the exhaust gas comes straight from, the lambda probe 16 is always at least approximately the same flow. For all three connected to the exhaust manifold 1, 1 'inlet pipes 6, 6 ', 7, 7' and 8, 8 'thus result in substantially equal inflow conditions. As a result, the engine control can be improved accordingly.

As shown in FIGS. 3 and 4, the lambda probe 16, 16 'can be screwed into the recess 15. For this purpose, the lambda probe 16, 16 'has an external thread 18 and the recess 15 an internal thread 19.

In the walls of the collector housing 9, 9 'is also formed, as can be seen for example in Fig. 3, an outlet opening 20a surrounding connecting piece 20 for an outlet pipe 21, which is designed in particular as a flow pipe for the catalyst. However, the outlet pipe 21 can also, as shown in Fig. 6, be integrally formed on the collector housing 9, 9 '. In both cases, the flow pipe 21 is formed so that the catalyst is optimally flowed by the exhaust gas stream.

The inflow pipe 21 is also guided to close in front of the catalyst body 3b. As a result, an annular space 21a is formed between the outlet tube 21 and the inlet funnel 3a, 3a 'of the catalyst housing 3, 3', which is connected in shunt to the exhaust gas flow and acts as an insulation for the exhaust gas flow.

The inlet pipes 6, 6 ', 7, 7' and 8, 8 'are each connected by welding to the collector housing 9, 9'. The same applies to the outlet pipe 21 in the variant shown in Figures 1 to 5, while in the variant shown in Fig. 6, as stated, the outlet pipe 21 is integrally formed on the collector housing 9, 9 '. The weld is located on the outside of the exhaust system, so that no welding Impurities can get into the interior of the exhaust system. The same applies to the welding of the inlet pipes 6, 6 ', 7, 7' and 8, 8 'to the motor flanges 2, 2'.

The inlet pipes 6, 6 ', 7, 7' and 8, 8 'are each preferably made by hydroforming and have an oval cross-section in a central region between their respective inlet end and their respective outlet end. By the said type of production and this training with oval cross-section results in a relatively high deformability of the inlet pipes 6, 6 ', 7, 7' and 8, 8 ', so that when heating a length compensation can take place.

As can be seen in the figures, the exhaust manifolds 1, 1 'with inlet pipes 6, 6', 7, 7 'and 8, 8' and the collector housing 9, 9 ', but without outlet pipe 21, are mirror-symmetrical to a plane IV, which at the same time forms the longitudinal center plane of the motor flange 2, 2 '. The recess 15 for the lambda probe 16 and the lambda probe 16 itself are formed mirror-symmetrically to this plane IV. As can be seen, thereby the two exhaust manifolds 1 and 1 'are substantially identical to each other, although the continuing elements of the exhaust system such as outlet pipe 21 and catalyst housing 3, 3' are formed differently.

The inlet pipes 6, 6 ', 7, 7' and 8, 8 'are also shaped so that they not only hold the screw holes 22 for mounting the motor flange 2, 2' as accessible as possible on the engine block, but also so that the exhaust gas streams I, II and III are inclined to a plane V, which is perpendicular to the exhaust gas flow direction VI in the outlet pipe 21. The inclination is chosen so that the exhaust gas flow directions I, II and III on entering the collector housing 9, 9 'on the same side of the plane V have, as the exhaust gas flow direction VI in the outlet tube 21. As a result, a good exhaust gas flow management is achieved with low back pressure.

Overall, there is an exhaust system with good exhaust gas flow, which mainly connects a uniform flow of the lambda probe 16, 16 'with a relatively low exhaust gas pressure. In addition, a better Katalysatoranströmung can be achieved, since the rebuilding of the flow to the lambda probe 16, 16 'takes place and therefore both streams can be formed separately from each other.

Also particularly advantageous is the combination of a collector housing 9, 9 'of relatively rigid material and relatively soft inlet pipes 6, 6', 7, 7 ', 8, 8'. Collector housing 9, 9 'and inlet pipes 6, 6', 7, 7 '8, 8' are each relatively easy to produce, with high accuracy can be met. In addition, this can be a particularly compact arrangement with close-coupled catalyst can be created.

LIST OF REFERENCE NUMBERS

1, 1 '

exhaust manifold

2, 2 '

motor flange

3, 3 '

catalytic converter housing

3a, 3a '

inlet funnel

3b

catalyst body

4, 4 '

exhaust pipe

5, 5 '

flange

6, 6 '

inlet pipe

7, 7 '

inlet pipe

8, 8 '

inlet pipe

9, 9 '

collector housing

10

spigot

11

spigot

12

spigot

13

plenum

14

assembly point

15

recess

16, 16 '

lambda probe

17

probe tip

18

external thread

19

inner thread

20

spigot

20a

outlet

21

outlet pipe

21 a

annulus

22

screw hole

I

Exhaust gas flow direction

II

Exhaust gas flow direction

III

Exhaust gas flow direction

IV

midplane

V

level

VI

Exhaust gas flow direction

Claims (10)

1. An exhaust system of a combustion engine having at least one exhaust manifold (1, 1') with a plurality of inlet pipes (6, 6', 7, 7', 8, 8') for connection to exhaust ports of the combustion engine and having a collector device (9, 9') for the merging of the inlet pipes (6, 6', 7, 7', 8, 8') which has one outlet opening (20a) which is connected to subsequent elements of the exhaust system, in particular to a catalytic converter housing (3, 3'), wherein the collector device (9, 9') is made as a one-piece collector housing,
   characterized in that
   the collector device (9, 9') consists of a material stiff in bending; and is made as a collector housing (9, 9') separate from the following catalytic converter housing (3, 3') with the catalytic converter inlet funnel (3a, 3a'); and in that the inlet pipes (6, 6', 7, 7', 8, 8') are made of material relatively flexible with respect to the collector housing (9, 9').
2. An exhaust system in accordance with claim 1, characterized in that the collector housing (9, 9') has at least two apertures, in particular three apertures, for the connection of inlet pipes (6, 6', 7, 7', 8, 8') and has an outlet opening (20a) and/ or an aperture (15) for the insertion of a lambda probe (16, 16').
3. An exhaust system in accordance with any one of the preceding claims, characterized in that an outlet pipe (20) is connected to the outlet opening (20a), wherein the outlet pipe (20) is preferably made as a catalytic converter inflow pipe, wherein the catalytic converter inflow pipe (20) is likewise preferably guided up to just before the catalytic converter, and wherein the catalytic converter housing (3, 3') is connected directly to the collector housing (9, 9') via a pipe (3a, 3a'), in particular a funnel-shaped pipe, surrounding the catalytic converter inflow pipe (20).
4. An exhaust system in accordance with any one of the preceding claims, characterized in that the apertures in the collector housing (9, 9') are at least partly stamped out apertures; and/or in that the collector housing (9, 9') is manufactured by internal high pressure shaping.
5. An exhaust system in accordance with any one of the preceding claims, characterized in that the inlet pipes (6, 6', 7, 7', 8, 8') open into the collector housing (9, 9') such that the exhaust flow directions (I, II, III) of all exhaust flows merge at a collection point (14), wherein a lambda probe (16) is preferably arranged in the collector housing (9, 9') such that the probe tip (17) is located at the collection point (14).
6. An exhaust system in accordance with any one of the preceding claims, characterized in that the inlet pipes (6, 6', 7, 7', 8, 8') open into the collector housing (9, 9') such that the exhaust flow directions (I, II, III) are each inclined with respect to a plane (V) extending perpendicular to the exhaust flow direction (VI) in the outlet opening (20a), and indeed such that the exhaust flow directions (I, II, III) of the inlet pipes (6, 6', 7, 7', 8, 8') face the same side of this plane (V) as the exhaust flow direction (VI) in the outlet pipe (21).
7. An exhaust system in accordance with any one of the preceding claims, characterized in that the lambda probe (16) is arranged at the side of the collector housing (9, 9') remote from the outlet opening (20a); and/or in that the inlet pipes (6, 6', 7, 7', 8, 8') open into the collector housing (9, 9') such that the collection point (14) is located in the interior (13) of the collector housing (9').
8. An exhaust system in accordance with any one of the preceding claims, characterized in that the collector housing (9, 9') has molded connection stubs (10, 11, 12, 20) for the inlet pipes (6, 6', 7, 7', 8, 8') and/or for the outlet pipe (21).
9. An exhaust system in accordance with any one of the preceding claims, characterized in that the collector housing (9, 9') is at least partly made in mirror symmetry with respect to a plane (IV) which extends perpendicular to the connection line of the exhaust ports of the combustion engine, wherein the inlet pipes (6, 6', 7, 7', 8, 8') and/or the lambda probe (16, 16') are preferably also arranged in mirror symmetry with respect to this plane (IV).
10. An exhaust system in accordance with any one of the preceding claims, characterized in that the inlet pipes (6, 6', 7, 7', 8, 8') are comparatively flexible; in particular in that they have an oval cross-section at least section-wise; and/or in that the inlet pipes (6, 6', 7, 7', 8; 8') are manufactured by internal high pressure shaping.

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