DE10301438A1 - Exhaust manifold for internal combustion engine, has at least one exhaust pipe and coolant chamber through which coolant can be passed so that exhaust gas passing through exhaust pipe is cooled - Google Patents

Abstract

The exhaust manifold (10) has at least one flange (12) for mounting on an internal combustion engine (5), at least one exhaust pipe (14) and coolant chamber (26) through which a coolant can be passed so that exhaust gas passing through the exhaust pipe is cooled. The flange is at least partly hollow and coolant chamber is formed inside the flange.

Description

The invention relates generally a system with which the exhaust gas of an internal combustion engine is cooled can.

In modern internal combustion engines become common Catalysts used to reduce the proportion of pollutants in the exhaust as low as possible to keep. The efficiency of the catalyst depends crucially on that the catalyst is at its operating temperature. This is the currently usual Materials above 250 ° C. So that the catalyst its operating temperature after a cold start the internal combustion engine as possible achieved quickly, he is possible arranged close to the internal combustion engine, so that the exhaust gas as possible little cools, before it reaches the catalyst and can heat it up. The way this way achieved rapid warming However, the catalyst inevitably carries the risk that the catalyst overheats when the internal combustion engine for a long time with high power is operated. The then entering with a very high temperature in the exhaust manifold Exhaust gas can namely, before it reaches the catalyst, only very little to cool. Another disadvantage is that the catalyst outside at high temperatures Its optimum performance range works and the catalytic Effect is reduced. Furthermore, due to the high temperatures expensive materials and elaborate constructions necessary.

There are different ways, excessive temperatures to prevent the catalyst. For example, at full load of Motors are injected with more fuel than actually optimal Combustion is required, which causes the exhaust gas temperature sinks. A disadvantage of this solution are the heightened Fuel economy and the increased Emissions.

The object of the invention is in, constructively overheating to prevent the catalyst.

For this purpose, an exhaust manifold is provided according to the invention with at least one flange zw mounting to an internal combustion engine, at least an exhaust pipe and a coolant space, through which a coolant can be routed so that the passed through the exhaust pipe Cooled exhaust gas becomes. The invention is based on the idea, the exhaust gas directly to cool when exiting the engine block, ie where it is the highest temperature Has. In this way, the maximum possible temperature gradient between the exhaust gas and the coolant used, resulting in efficient heat transfer from the exhaust gas to the coolant results. This results in particularly small dimensions, which with regard to the usual small space available in the engine compartment, is advantageous. It is furthermore advantageous that the exhaust gas cooling system is integrated in the exhaust manifold is; the exhaust manifold So it can be delivered as a prefabricated module, so that when assembling the engine no additional Effort is required to install the exhaust gas cooling system. Another Advantage of the invention is that due to the rapid cooling of the Exhaust gases thermally the following components in the exhaust pipe less stress and their life is extended.

With the exhaust gas cooling system according to the invention can reduce the exhaust gas temperature by about 150 ° be, ie from about 900 ° C up to 1050 ° C to temperatures of the order of magnitude from 750 ° C up to 900 ° C.

According to a preferred embodiment of Invention, the flange is formed of two half-shells, so that the coolant space formed by the hollow interior of the flange. The two half shells consist of sheet metal and are welded together. The Exhaust pipe passes through the flange in a sealed manner, leaving the coolant immediately flushed around the exhaust pipe. In this way, a good heat transfer from the exhaust gas to the coolant reached.

According to a second preferred embodiment A cuff is provided which holds the exhaust pipe near the flange encloses and through which the coolant flows. The collar is tightly connected to the exhaust pipe, so that even in this embodiment the exhaust pipe directly from the coolant flows around becomes.

According to a third embodiment is a coolant line provided, the interior of which is the coolant space forms, wherein the coolant line passes through the interior of the exhaust pipe. In this embodiment the heat transfer takes place not through the wall of the exhaust pipe, but through the wall of the coolant line therethrough. The coolant line can be in the flange of the exhaust manifold be integrated and protrudes arcuately into the exhaust pipe, so that a large surface is available for heat transfer.

Advantageous embodiments of Invention will become apparent from the dependent claims.

The invention will be described below various embodiments described in the attached Drawings are shown. In these show:

1 an exhaust manifold according to a first embodiment of the invention in a cal matic view;

2 schematically a section along the plane II-II of 1 ;

3 schematically a section along the plane III-III of 1 ;

4 in a schematic view corresponding to that of 3 a variant of the first embodiment;

5 the variant of 4 in a view corresponding to that of 2 ;

6 an exhaust manifold according to a second embodiment of the invention in a schematic view;

7 schematically a section along the plane VII-VII of 6 ;

8th in a schematic partial view of a variant of the second embodiment;

9 the exhaust manifold of 8th in a sectional view;

10 an exhaust manifold according to a third embodiment of the invention in a schematic sectional view.

In 1 is an engine block 5 an internal combustion engine shown. At the engine block 5 is an exhaust manifold 10 attached, which serves to collect the exhaust gases of the internal combustion engine and to a (not shown) to guide catalyst and muffler. The exhaust manifold 10 consists of a flange 12 , which is for mounting the exhaust manifold on the engine block 5 serves, several exhaust pipes 14 and a manifold 16 in which the exhaust pipes 14 lead.

The flange 12 is hollow and consists of two half-shells made of sheet metal, namely one of the engine block 5 facing mounting shell 18 and one from the engine block 5 facing away cover shell 20 (see in particular 2 ). On the mounting cup 18 may (not shown) mounting bolts, mounting eyes or the like may be provided by means of which the flange 12 on the engine block 5 can be attached. The exhaust pipe 14 passes through both the mounting cup 18 as well as the lid shell 20 and is sealed in the region of the passage through the corresponding half-shell, for example by welds 22 , Also for the tight connection of the mounting shell 18 with the lid shell 20 becomes a weld 24 used.

The hollow interior of the flange between the two half-shells 18 . 20 forms a coolant space 26 through which a coolant, such as water, can flow. For the coolant are an inlet 28 and a process 30 provided, wherein at the inlet a valve 31 is provided, by means of which the supply of coolant to the coolant space can be regulated.

When cold starting the internal combustion engine, the inlet 28 for the coolant from a valve (not shown) usually be closed, so that through the exhaust pipes 14 flowing exhaust gas as little heat as possible is withdrawn. In this way, a catalyst located downstream of the exhaust manifold is brought to its operating temperature as quickly as possible.

At low outdoor temperatures, once the operating temperature of the catalyst is reached, the valve can 31 in the inlet 28 to the coolant space 26 be opened so that the coolant through the flange 12 formed coolant space 26 flows while the exhaust pipes 14 flows around. The resulting heating of the coolant can be used in a (not shown) heat exchanger to heat the air supplied to the interior of a vehicle. In this way, an additional heating system is provided, which can provide hot air much faster after a cold start of the engine, as this is a conventional heating system, through whose heat exchanger, the coolant flowing through the engine block is passed. Such an additional heating system is particularly advantageous in modern, fuel-efficient internal combustion engines, which generate so little waste heat due to their high efficiency that the delayed response of the conventional heating system is perceived by the vehicle occupants as disadvantageous.

It is also conceivable the coolant space 26 in the exhaust manifold parallel or in series with the coolant circuit to switch the internal combustion engine. This way results after a cold start a rapid warming of the engine, resulting in a low mechanical wear leads. In addition, will thus speeding up the response of the conventional heating system, so that a separate heating system is superfluous.

When the internal combustion engine has reached its operating temperature and is operated at high power for a long time, the valve becomes 31 in the inflow 28 to the coolant space 26 open in any case, so regardless of any need for additional heating power. In this operating condition, the requirements are reversed; it is not the coolant must be heated, but cooled the exhaust gas. In this way it is ensured that the catalyst does not exceed a certain upper temperature limit, from which it would come to a destruction of the catalyst.

In the 4 and 5 a variant of the first embodiment is shown. For those of the 1 to 3 known components, the same reference numerals are used, and reference is made to the above explanations.

The difference to the first embodiment is that the coolant not only the exhaust pipes 14 flows around directly, but also flows through the exhaust pipes. For this purpose, a coolant line 32 provided, which is transverse to the flow direction of the exhaust gas through the corresponding exhaust pipe 14 extends through. Each coolant line is tight in the wall of the corresponding exhaust pipe 14 used, for example Welded there way, so that the tightness is ensured by the exhaust pipe to the coolant chamber. The longitudinal axis of each coolant line is approximately parallel to the flow direction of the coolant from the inlet 28 the end 30 aligned ,. so that the best possible flow occurs.

The advantage of this variant is in that a larger surface to the heat transfer from the exhaust gas to the coolant to disposal stands.

In the 6 and 7 an exhaust manifold according to a second embodiment is shown. For the components known from the first embodiment, the same reference numerals are used, and reference is made to the above explanations.

The most significant difference between the first and second embodiments is that in the second embodiment, the coolant space 26 not in the flange 12 is formed, but outside the flange 12 , but immediately adjacent to it. The coolant space 26 is formed by a cuff 34 that the corresponding exhaust pipe 14 encloses annularly. The sleeve is made of sheet metal and can be deep drawn or made in a similar way.

Every cuff 34 is close to the outside of the corresponding exhaust pipe with respect to the flow direction of the exhaust gas at its upstream and at its downstream end 14 attached, for example, welded. Thus, the coolant space 26 formed as an annulus, on the inside of the outer surface of the corresponding exhaust pipe 14 and on the outside of the inner wall of the corresponding cuff 34 is demarcated. Every cuff 34 is with a feed 28 and a process 30 Provided,. the inlet 28 on the upstream side and the drain 30 is arranged on the downstream side. As in 6 can be seen, is the process 30 a cuff 34 with the enema 28 connected to the subsequent cuff. In this way, the coolant flows, based on the representation of 6 , through the series-connected coolant chambers 26 from the left cuff over the two in the middle arranged to the right cuff and from there over the drain 30 in a coolant circuit.

That through the coolant spaces 26 Guided coolant thus ensures in the second embodiment for a cooling of the exhaust gas in the immediate vicinity of the engine block 5 ,

In the 8th and 9 a variant of the second embodiment is shown. In contrast to the cuff according to the 6 and 7 , which has a continuous annular space, is in the 8th and 9 shown sleeve formed with a corrugated profile. In their areas with a smaller diameter, the sleeve lies on the outside of the exhaust pipe 14 on. In this way is a spiraling coolant space 26 created in the embodiment shown in four turns around the exhaust pipe 14 extends around. The cuff is preferably a flow-pressed sheet metal part.

At its upstream and downstream ends is the cuff 34 on the exhaust pipe 14 welded. This is through welds 22 symbolizes. It is not necessary that the individual turns of the spiral coolant space 26 sealed against each other; slight overflow losses from one gear to the next affect the cooling effect at most slightly.

In 10 An exhaust manifold according to a third embodiment is shown. For the components known from the preceding embodiments, the same reference numerals are used, and reference is made to the above explanations in this respect.

The most significant difference between the third embodiment and the previous embodiments is that in the third embodiment, not the exhaust pipe 14 is lapped by the coolant, but that the coolant in a coolant line 32 is guided across the exhaust gas flow through the exhaust pipe 14 flows. The coolant space 26 So it is inside the coolant line 32 formed, and the heat transfer takes place through the wall of the coolant line 32 therethrough.

As in 10 can be seen, the flange points 12 the exhaust manifold for each exhaust pipe 14 a neck 36 on, in which the corresponding exhaust pipe 14 is inserted. The exhaust pipes 14 however, do not extend all the way to the engine block 5 but start at a certain distance downstream from the engine block. For fastening and sealing the exhaust pipes 14 in the neck 36 is each a weld 22 intended.

Across the neck 36 extends the coolant line 32 , being in the neck 36 upstream of the front end of the corresponding exhaust pipe 14 is arranged. To increase the surface available for heat transfer, the coolant line is 32 inside each neck 36 with a bend running down into the exhaust pipe 14 extends into it.

In each of the embodiments shown, the Coolant line and the flow rate of coolant be coordinated so that the liquid evaporates, causing an even higher one cooling capacity is achievable. The steam can then be liquefied again.

5:

block

10:

exhaust manifold

12:

flange

14:

exhaust pipe

16:

manifold

18:

mounting shell

20:

cover shell

22:

Weld

24:

Weld

26:

Coolant space

28:

Intake

30:

procedure

31:

Valve

32:

Coolant line

34:

cuff

36:

Support

Claims (19)

Exhaust manifold ( 10 ) with at least one flange ( 12 ) for mounting on an internal combustion engine ( 5 ), at least one exhaust pipe ( 14 ) and a coolant space ( 26 ), through which a coolant can be passed, so that through the exhaust pipe ( 14 ) Guided exhaust gas is cooled. Exhaust manifold according to claim 1, characterized in that the flange ( 12 ) is at least partially hollow and the coolant space ( 26 ) inside the flange ( 12 ) is formed. Exhaust manifold according to claim 2, characterized in that the exhaust pipe ( 14 ) through the hollow flange ( 12 ) and through the coolant space ( 26 ). Exhaust manifold according to one of claims 2 and 3, characterized in that the flange ( 12 ) of two half-shells ( 18 . 20 ), which are connected to each other in a dense manner. Exhaust manifold according to claim 4, characterized in that the two half-shells ( 18 . 20 ) are welded together. Exhaust manifold according to one of the preceding claims, characterized in that a coolant line ( 32 ) is provided which extends through the exhaust pipe ( 14 ) and in the region of their passage through the wall of the exhaust pipe ( 14 ) is sealed. Exhaust manifold according to one of the preceding claims, characterized in that an inlet ( 28 ) for the coolant and a drain ( 30 ) are provided for the coolant, which at opposite ends of the exhaust manifold ( 10 ) are arranged. Exhaust manifold according to claim 1, characterized in that a cuff ( 34 ) is provided, which the exhaust pipe ( 14 ) near the flange ( 12 ) and in which the coolant space ( 26 ) is formed. Exhaust manifold according to claim 8, characterized in that the coolant space ( 26 ) on its inside from the exhaust pipe ( 14 ) is limited. Exhaust manifold according to claim 9, characterized in that the cuff ( 34 ) at its relative to the exhaust pipe ( 14 ) upstream and downstream end close to the exhaust pipe ( 14 ) is attached. Exhaust manifold according to claim 10, characterized in that the cuff ( 34 ) with the exhaust pipe ( 14 ) is welded. Exhaust manifold according to one of claims 8 to 11, characterized in that the cuff ( 34 ) an inlet ( 28 ) and a process ( 30 ), wherein the feed ( 28 ) relative to the exhaust pipe ( 14 ) upstream of the process ( 30 ) is arranged. Exhaust manifold according to one of claims 8 to 12, characterized in that the coolant space ( 26 ) is annular, wherein the central axis of the coolant space ( 26 ) with the central axis of the exhaust pipe ( 14 ) coincides. Exhaust manifold according to one of claims 8 to 12, characterized in that the coolant space ( 26 ) spirally around the exhaust pipe ( 14 ) runs around. Exhaust manifold according to one of claims 8 to 14, characterized in that the sleeve ( 34 ) is a Fließgepreßtes sheet metal part. Exhaust manifold according to claim 1, characterized in that a coolant line ( 32 ) is provided, whose interior is the coolant space ( 26 ) and that the coolant line ( 32 ) through the interior of the exhaust pipe ( 14 ) runs. Exhaust manifold according to claim 16, characterized in that the coolant line ( 32 ) in the flange ( 12 ) is attached. Exhaust manifold according to claim 17, characterized in that the exhaust pipe ( 14 ) in the flange ( 12 ) begins downstream of the point at which the coolant line ( 32 ) in the flange ( 12 ), and that the coolant line ( 32 ) by means of a bent portion in the exhaust pipe ( 14 ) extends into it. Exhaust manifold according to one of vorherge dependent claims, characterized in that a valve ( 31 ) is provided, by means of which the inflow of coolant to the coolant space ( 26 ) can be shut off.