DE102011116360A1 - Exhaust system for an internal combustion engine, internal combustion engine and vehicle - Google Patents

Abstract

An exhaust system (11, 11 ') for an internal combustion engine (1) having a plurality of cylinders (3, 4, 5, 6), a cylinder head (2) and an engine block, the exhaust system including an exhaust manifold (12) mounted in the cylinder head (12). 2) and having flow channels (7, 8, 9, 10), and an outlet pipe (13, 13 ') which is connected to a head flange (14) of the cylinder head (2). The flow channels (7, 8, 9, 10) each extend from one of the cylinders (3, 4, 5, 6) to a head flange (14). At least two of the flow channels (7, 10), which are connected to non-sequentially ignited cylinders (3, 6), are brought together inside the cylinder head (2) and form a common flow channel (15). At least one further flow channel (16), which is connected to a sequentially ignited cylinder (4), is guided separately up to the head flange (14). The common flow channel (15) is merged with the further flow channel (16) only in the outlet pipe (13, 13 ').

Description

An internal combustion engine is typically equipped with an exhaust system, with which exhaust gases, which are generated in the internal combustion engine or in cylinders of the internal combustion engine, are discharged. The exhaust gases are led from the respective cylinders via an exhaust manifold to a common outlet and then into a catalyst, removing undesired components of the exhaust gases or converting them into non-toxic substances.

The exhaust manifold may be manufactured as a separate component that is mounted to the cylinder head of the internal combustion engine by bolts or the like. The exhaust manifold is exposed to the atmosphere and designed as a member separate from the cylinder head, so that the exhaust manifold can be cooled not by a cooling water jacket but by the ambient air. However, because the exhaust manifold is separately mounted to the engine, assembly costs may increase. The narrow space in the engine compartment limits the technical design possibilities of the exhaust manifold.

The publication DE 10 2008 058 852 A1 discloses an exhaust system of an internal combustion engine in which the cylinder head and the exhaust manifold are integrally formed. This arrangement has the advantage that the assembly is simplified and the spatial utilization of the engine compartment is improved. However, it is possible that due to the compact design, the exhaust resistance and fuel consumption increase. To prevent this problem, the DE 10 2008 058 852 A1 in that the individual passages from the cylinders to the exhaust flange are arranged in the cylinder head so that less turbulence and less flow resistance is achieved. Consequently, the fuel consumption can be reduced.

However, further improvements in exhaust systems for internal combustion engines are desirable to further reduce fuel consumption.

An exhaust system for an internal combustion engine having a plurality of cylinders, a cylinder head, and an engine block is provided having an exhaust manifold integrated with the cylinder head and another exhaust pipe connected to a head flange of the cylinder head. The exhaust manifold, which is integrated in the cylinder head, has flow channels extending from each of the cylinders to the head flange, respectively. At least two of the flow channels, which are connected to cylinders that are not sequentially ignited in a firing order, are brought together within the cylinder head and form a common flow channel. At least one further flow channel, which is connected to a successively ignited cylinder in the firing order, is guided separately up to the head flange. The common flow channel is merged with the further flow channel only in the outlet pipe.

The exhaust system of the present invention is thus partially integrated within the cylinder head and partially disposed outside of the cylinder head, as in a separate exhaust manifold. In particular, two flow channels of cylinders that are not sequentially arranged in the firing order are merged within the cylinder head, in contrast, at least one flow passage from a cylinder ignited sequentially in firing order is not detected outside the cylinder head in the exhaust pipe connected to the flow tube of at least one cylinder, which is sequentially in the firing order. The terms exhaust system and exhaust system, exhaust manifold and exhaust manifold are synonymous.

This arrangement has the advantage that the length of the flow channel of successively ignited cylinders is extended compared to an integrated exhaust manifold. This leads to an improved separation of the exhaust pulses, a lower residual gas content and a power and torque increase over an exhaust manifold, in which all the flow channels are connected to each other in the cylinder head.

For example, a typical firing order in a four-cylinder internal combustion engine is IIII-IV-II. In this example, the flow channels of the cylinders I and IV can be merged in the cylinder head and the flow channel of cylinders II and III are merged with the common flow channel of the cylinders I and IV only outside the cylinder head downstream of the head flange within the outlet pipe.

In one embodiment, the further flow channel is connected to the common flow channel downstream of the cylinder head flange. The further flow channel is connected to a cylinder, which is brought together in succession with one of the cylinders, which is connected to the common flow channel, only downstream of the head flange. Thus, the length of the flows from the cylinders to a point where exhaust gas from two consecutive cylinders is merged is increased. Consequently, due to the additional outlet tube, the exhaust pulses from two consecutive cylinders are better separated.

In a further embodiment, a third flow channel is provided, which extends from a cylinder which follows one another in the firing order of one of the two cylinders, which are connected to the common flow channel. The third flow channel is only connected to the common flow channel downstream of the cylinder head.

For example, in a four-cylinder internal combustion engine having a firing order of I-III-IV-II, the flow channels of cylinders I and IV are merged in the cylinder head and the flow channel of cylinder II and the flow channel of cylinder III are merged with the common flow channel of cylinders I and IV merged only outside of the cylinder head downstream of the head flange within the outlet pipe.

The flow channel from the cylinder III can be connected further downstream from the point at which the flow channel from the cylinder II is connected to the common flow channel of the cylinders I and IV with the common flow channel of the cylinders I, IV and II. Alternatively, the flow passage from the cylinder III at the same point as the flow passage from the cylinder II may be connected to the common flow passage of the cylinders I and IV.

In one embodiment, the outlet tube has at least two separate flow branches that are merged to form a header flow branch. The two separate flow branches are upstream and the collection flow branch is downstream. One of the flow branches is connected to the common flow channel and the other flow branch is connected to the further flow channel of the cylinder head integrated exhaust manifold. Thus, the two flow branches extend the length of the separation of the exhaust flows of successively ignited cylinders.

In one embodiment, the outlet tube has a partition wall at an inlet end, wherein two separate flow channels or flow branches are formed.

The outlet tube has at least two inlet flow channels and a single common outlet flow channel connected to the inlet flow channels. The number of inlet flow channels corresponds to the number of flow channels, which are arranged separately from one another on the head flange of the cylinder head.

In one embodiment, the outlet tube has an inlet flange with at least two inlet openings, an outlet flange with an outlet opening, and flow channels. The inlet flange is connected to the head flange of the integrated exhaust manifold and the flow channels each extend from one of the inlet openings to the outlet opening. The flow channels from the inlet openings are separated by a predetermined distance in the direction of the outlet openings and are merged after this distance and form a collecting flow channel.

The predetermined distance may be predetermined for each engine type, such as the number of cylinders and power, to optimize performance and other characteristics of the internal combustion engine. The usable space in the engine type may also be taken into account to indicate the optimum performance in the given space.

In a further development, one of the inlet openings is connected to the common flow channel and one of the inlet openings is connected to the further flow channel in the cylinder head.

In another embodiment, flow channels of two further cylinders that are not sequentially arranged in a firing order are merged within the cylinder head and form a second common flow passage.

For example, in a four-cylinder internal combustion engine having a firing order of I-III-IV-II, the flow channels of cylinders I and IV may form a first common flow channel in the cylinder head and the flow channels of cylinders II and III form a second common flow channel in the cylinder head , The two cylinders of each of these pairs of cylinders are thus not sequentially in firing order. By contrast, cylinders of different pairs follow one after the other. The two common flow channels are separated within the cylinder head and are merged only downstream of the cylinder head outside of the cylinder head and within an outlet tube.

The second common flow channel is connected to the first common flow channel a predetermined distance downstream of the head flange within the outlet tube to provide the desired better separation of the exhaust pulses from an integrated exhaust manifold.

An internal combustion engine having a plurality of cylinders, an engine block, a cylinder head, and an exhaust system according to any one of the preceding embodiments is also provided. One A vehicle, for example a motor vehicle, with an internal combustion engine and an exhaust system according to one of the preceding embodiments is also indicated.

In summary, integrated exhaust manifold (IEM) cylinder heads provide cost savings through the elimination of the conventional, separate manifold, but with additional overheads such as: B. a larger radiator or the more complex cylinder head construction, be reduced slightly. The reduction of the surface to the catalyst allows a faster heating and thus the reduction of emissions. In stationary engine operation, the cooling of the integrated in the cylinder head Beriches the exhaust system leads to lower exhaust temperatures and thus to a lower Anfettungsbedarf.

The separation of the exhaust pulses in a 4-cylinder engine is carried out by the merger of the runner of cylinder I and IV and cylinder II and III. A conventional 4-1 IEM design of a four-cylinder engine is that the flow channels of all cylinders are merged within the cylinder head. The compact design of an integrated IEM and the lack of separation of the exhaust pulses can lead to a higher residual gas content and a loss of power and torque. In contrast, conventional external exhaust manifolds for naturally aspirated engines are characterized by long runners.

These problems can be avoided by the use of an exhaust system according to the invention in which the flow channels of two non-consecutive cylinders are merged within the cylinder head, while the flow channels of the successive cylinders are merged only outside the cylinder head in an additional exhaust pipe mounted on the cylinder head flange is. Thus, the length of the flow is lengthened from two consecutive cylinders in the firing order to their merging with that of an integral exhaust manifold.

In summary, the advantages of an exhaust manifold integrated into the cylinder head are combined with those of excellent gas dynamics and pulse separation of the exhaust stroke in a conventional exhaust manifold in the exhaust system of the present invention. The invention combines the compact design of a 4-1 IEM manifold with the good pulse separation and performance of a conventional exhaust manifold.

It shows slight performance benefits by merging cylinder I and IV and II and III in the cylinder head. However, these can be significantly increased if the channel separation of the two exhaust gas streams is still maintained a bit behind the head flange. By combining both measures, the performance of the internal combustion engine can be further improved.

Embodiments will now be explained in more detail with reference to the drawings.

1 shows a schematic plan view of an internal combustion engine with an exhaust system according to a first embodiment,

2 shows a perspective view of the exhaust-carrying inner surfaces of the exhaust system,

3 shows a second perspective view of the exhaust-carrying inner surfaces of the exhaust system of 2 .

4 shows a cross section of the exhaust system of 1 .

5 shows a cross section of an exhaust system according to a second embodiment, and

6 shows diagrams of the performance of internal combustion engines with different exhaust systems.

1 shows a schematic plan view of an internal combustion engine 1 according to a first embodiment. The internal combustion engine 1 has a cylinder head 2 , one in 1 not shown engine block and four cylinders 3 . 4 . 5 . 6 on, which form the combustion chambers.

The four cylinders 3 . 4 . 5 . 6 are each with a flow channel 7 . 8th . 9 . 10 an exhaust system 11 of the internal combustion engine 1 connected by the exhaust gases from the combustion reaction in the cylinders to an in 1 not shown catalyst are performed. The flow channels 7 . 8th . 9 . 10 are in the cylinder head 2 integrated and are part of an exhaust manifold 12 in the cylinder head 2 is integrated. However, the exhaust system of the invention is not limited to four-cylinder internal combustion engines and may be used with internal combustion engines having fewer or more than four cylinders.

The exhaust system 11 points next to the flow channels 7 . 8th . 9 . 10 in the cylinder head 2 integrated, an additional outlet pipe 13 on that on a head flange 14 of the cylinder head 2 is mounted.

The outlet pipe 13 has an inlet flange 17 on the head flange 14 of the cylinder head 2 is mounted, and an outlet flange 18 which is connected to other components, not shown, of the exhaust system, such as a catalytic converter.

The internal combustion engine 1 has four cylinders 3 . 4 . 5 . 6 which are ignited in the firing order I-III-IV-II, ie in the order cylinder 3 , Cylinder 5 , Cylinder 6 , Cylinder 4 ,

The flow channels 7 and 10 the cylinder 3 and 6 that correspond to the cylinders I and IV of the firing order are inside the cylinder head 2 merged and form a first common flow channel 15 at the head flange 14 , Also are the flow channels 8th and 9 the cylinder II and III of the firing order within the cylinder head 2 merged and form a second common flow channel 16 at the head flange 14 , The first common flow channel 15 However, it is separate from the second common flow channel 16 inside the cylinder head 2 ,

The first common flow channel 15 is just outside the cylinder head 2 with the second common flow channel 16 connected. Consequently, the exhaust gas flow of the first flow channel is 15 only in contact with the exhaust gas flow of the second common flow channel 16 downstream of the cylinder head 2 and outside the cylinder head 2 ,

According to the invention are thus flow channels of non sequentially ignited cylinders within the cylinder head 2 connected with each other. Flow channels of sequentially ignited cylinders are downstream of the cylinder head 2 connected with each other.

Flows of exhaust gases from cylinders, which are fired sequentially in the firing order, meet only downstream of the cylinder head 2 within the additional outlet tube 13 one another because the two common flow channels 15 . 16 inside the cylinder head 2 are separated and only after a predetermined length l within the outlet pipe 13 connected to each other.

Consequently, exhaust pulses successively ignited cylinder meet only downstream of the head flange 14 after a length l. The outlet pipe 13 sees a kind of extension piece for the integrated exhaust manifold 12 in front.

The 2 and 3 show perspective views of the exhaust-carrying inner surfaces of the exhaust system 1 , 2 shows a perspective top view and 3 a perspective side view. In the 2 and 3 is shown every flow channel 7 . 8th . 9 . 10 the exhaust manifold 12 two branches 7 ' . 7 '' . 8th' . 8th'' . 9 ' . 9 . 10 ' . 10 '' each having one of two outlet openings of the respective cylinder 3 . 4 . 5 . 6 are connected.

These two branches 7 ' . 7 '' . 8th' . 8th'' . 9 ' . 9 '' . 10 ' . 10 '' are inside the cylinder head 2 and upstream of the beginning of the common flow channels 15 . 16 of the cylinder head 2 merged. In the 2 and 3 is the head flange, which is the boundary between the integrated exhaust manifold 12 and the additional outlet tube 13 forms, with a line 14 shown graphically.

The 2 and 3 show that on the head flange 14 the flow channels 7 and 10 the cylinder 3 and 6 that correspond to the cylinder of the firing order I and IV and into the common flow channel 15 merge, below the flow channels 8th and 9 the cylinder 4 and 5 , which correspond to the cylinder II and III of the firing order, and the second common flow channel 16 are arranged.

In 3 is shown graphically that the outlet pipe 13 two separate branches 19 . 20 to the inlet end 21 the outlet pipe 13 having. These two separate branches 19 . 20 are inside the outlet pipe 12 only after a predetermined distance I merged to a collecting flow pipe 21 to build. The exhaust gas flow from the cylinders I and IV in the firing order, ie cylinders 3 . 6 , are from the flow of cylinders II and III, ie cylinders 4 . 5 , also outside of the cylinder head 2 kept separate. The flow length of the exhaust gases from successively ignited cylinders is thus by means of the outlet pipe 13 extended.

The position of merging the flow channels 7 and 10 inside the cylinder head is with the line 15 and the merging of the flow channels 8th and 9 with the line 16 in the 3 shown graphically.

4 shows a schematic cross section of the connection between the cylinder head 2 , in particular the head flange 14 and the outlet pipe 13 ,

The inlet flange 17 the outlet pipe 13 has two inlet openings 22 . 23 and the outlet flange 18 a single outlet opening 24 on. The two inlet ports see two flow channels 19 . 20 inside the outlet pipe 13 which extends a predetermined distance in the direction of the outlet opening 21 extend apart from each other. After this predetermined distance are the flow channels 19 . 20 merged and form one Collecting flow channel 21 , The transition from the separate flow channels 19 . 20 to the collecting flow channel 21 is with the line 25 in 3 shown.

One of the inlet openings 22 is with the first common flow channel 15 of the cylinder head 2 connected and the second inlet opening 23 is with the second common flow channel 16 of the cylinder 2 connected. As a result, exhaust flows from successively fired cylinders only meet at the point that coincides with the line 25 is designated.

5 shows a cross section of a part of an exhaust system 11 according to a second embodiment. The exhaust system 11 according to the second embodiment differs from the exhaust system 1 of the first embodiment by the construction of the outlet pipe 13 , In contrast to the first embodiment, the two flow channels 19 . 20 inside the outlet pipe 13 ' through a single partition 26 educated.

6 Figure 4 shows torque and residual gas content versus speed graphs for a 1.8 l naturally aspirated engine with 5 different exhaust manifolds, namely an external manifold design of a motor (square), two different 4-1 IEM designs (circle and rhombus), and two IEM designs with a combination of runners 1/4 and 2/3 (triangle). An inventive exhaust manifold for this particular engine based on a 4-2-1 concept is characterized by a 35 mm long continuation of the partition behind the head flange. The length of the continuation is system-dependent.

The use of an integrated exhaust manifold for a naturally aspirated engine may, for. For example, in a 1.8L engine, performance losses of up to 2kW and 4Nm over an external exhaust manifold. The exhaust system according to the invention allows a performance that corresponds to the performance of an external exhaust manifold, even with a more compact space.

LIST OF REFERENCE NUMBERS

1

internal combustion engine

2

cylinder head

3

cylinder

4

cylinder

5

cylinder

6

cylinder

7

flow channel

7 '

Branch of the flow channel

7 ''

Branch of the flow channel

8th

flow channel

8th'

Branch of the flow channel

8th''

Branch of the flow channel

9

flow channel

9 '

Branch of the flow channel

9 ''

Branch of the flow channel

10

flow channel

10

Branch of the flow channel

10 ''

Branch of the flow channel

11

Outlet system according to a first embodiment

11 '

Outlet system according to a second embodiment

12

integrated exhaust manifold

13

Outlet pipe according to a first embodiment

13 '

Outlet pipe according to a second embodiment

14

head flange

15

first common flow channel

16

second common flow channel

17

inlet flange

18

outlet flange

19

first branch

20

second branch

21

Collecting flow tube

22

first inlet opening

23

second inlet opening

24

outlet

25

Merging the currents

26

partition wall

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102008058852 A1 [0003, 0003]

Claims (12)

Exhaust system for a multi-cylinder internal combustion engine, a cylinder head, and an engine block, the exhaust system including an exhaust manifold ( 12 ) in the cylinder head ( 2 ) and flow channels ( 7 . 8th . 9 . 10 ) each extending from one of the cylinders ( 3 . 4 . 5 . 6 ) to a head flange ( 14 ), wherein at least two of the flow channels ( 7 . 10 ) with cylinders not ignited consecutively in a firing order ( 3 . 6 ) are interconnected within the cylinder head ( 2 ) and a common flow channel ( 15 ), and at least one further flow channel ( 16 ), with a cylinder ignited sequentially in the firing order ( 4 ), separated to the head flange ( 14 ), and an outlet tube ( 13 . 13 ' ), which with the head flange ( 14 ), wherein the common flow channel ( 15 ) with the further flow channel ( 16 ) first in the outlet pipe ( 13 . 13 ' ) is merged. Exhaust system according to claim 1, wherein the further flow channel ( 16 ) with the common flow channel ( 15 ) downstream of the head flange ( 2 ) connected is. Exhaust system according to claim 1 or claim 2, wherein a third flow channel ( 9 ) of a cylinder ( 5 ), which in the firing order one of the two cylinders ( 3 . 6 ) is below, downstream of the cylinder head ( 2 ) with the common flow channel ( 15 ) connected is. Exhaust system according to one of claims 1 to 3, wherein the outlet pipe ( 13 ) at least two separate flow branches ( 19 . 20 ) having. Exhaust system according to one of claims 1 to 4, wherein the outlet pipe ( 13 ' ) at an inlet end a partition wall ( 26 ), wherein two separate flow channels ( 19 . 20 ) are formed. Exhaust system according to one of claims 1 to 5, wherein the outlet pipe ( 13 ) at least two inlet flow channels ( 19 . 20 ) and a single common outlet flow channel ( 21 ) which communicates with the inlet flow channels ( 19 . 20 ) connected is. Exhaust system according to one of claims 1 to 6, wherein the outlet pipe ( 13 . 13 ' ) an inlet flange ( 17 ) with at least two inlet openings ( 22 . 23 ), an outlet flange ( 18 ) with an outlet opening ( 24 ), and flow channels ( 19 . 20 . 21 ), wherein the inlet flange ( 17 ) with the head flange ( 14 ) of the integrated exhaust manifold ( 12 ) and the flow channels ( 19 . 20 . 21 ) each from one of the inlet openings ( 22 . 23 ) to the outlet opening ( 24 ), wherein the flow channels ( 19 . 20 ) from the inlet openings ( 22 . 23 ) a predetermined distance in the direction of the outlet opening ( 24 ) are separated from each other and are merged after this route and a collecting flow channel ( 21 ) form. Exhaust system according to claim 7, wherein one of the inlet openings ( 22 ) with the common flow channel ( 15 ) and one of the inlet openings ( 23 ) with the further flow channel ( 16 ) connected is. Exhaust system according to one of claims 1 to 8, wherein flow channels ( 8th . 9 ) of two further cylinders ( 4 . 5 ), which are not consecutive in the firing order, within the cylinder head ( 2 ) are merged and a second common flow channel ( 16 ) form. Exhaust system according to claim 9, wherein the second common flow channel ( 16 ) with the first common flow channel ( 15 ) after a predetermined distance downstream of the head flange ( 14 ) within the outlet tube ( 13 ) connected is. An internal combustion engine having a plurality of cylinders, an engine block, a cylinder head and an exhaust system according to any one of claims 1 to 10. Vehicle with an internal combustion engine according to claim 11.

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