DE102016004576A1 - Exhaust manifold for an internal combustion engine, and method for operating such exhaust manifold - Google Patents

Abstract

The invention relates to an exhaust manifold (40) for an internal combustion engine (10), comprising at least one fluidically connectable with at least one combustion chamber (14) of the internal combustion engine (10) and exhaust gas from the combustion chamber (14) At least one injection element (46) is provided, by means of which at least a portion of the surface (44) with a cooling liquid (48) for cooling the guide element (42 ) is at least indirectly acted upon.

Description

The invention relates to an exhaust manifold for an internal combustion engine, in particular a motor vehicle, according to the preamble of patent claim 1, and method for operating such exhaust manifold.

Such an exhaust manifold for an internal combustion engine, in particular a motor vehicle, for example, is already the DE 10 2005 062 186 A1 to be known as known. The exhaust manifold comprises at least one guide element which has at least one exhaust duct, which can be fluidly connected to at least one combustion chamber of the internal combustion engine and can be flowed through by exhaust gas from the combustion chamber, for guiding the exhaust gas. Furthermore, the guide element has a side facing away from the exhaust gas channel, outside and in contact with air or in contact with air surface. The surface is surrounded by air, for example, or can be flowed around by air.

Further, the WO 2011/045659 A1 an exhaust manifold for an internal combustion engine, having a guide element which has at least one exhaust gas flow through the exhaust passage and an exhaust gas channel facing away from the outside surface. Through the surface, a cooling channel is at least partially limited, wherein the cooling channel can be flowed through by a cooling liquid. This cooling fluid can come into contact with the surface.

Furthermore, it is known from the general state of the art and in particular from production vehicle construction that the start and warm-up phase of an internal combustion engine has enormous potential for reducing pollutant emissions. Accordingly, a focus of the development of future internal combustion engines on a rapid heating of the entire system by reducing the heat dissipation.

Due to the unbroken trend of downsizing to reduce the CO ₂ emissions of motor vehicles, in particular passenger cars, with internal combustion engine drive, the specific torque and the specific power of internal combustion engines, in particular gasoline engines, are steadily increasing. This is made possible, among other things, by charging the internal combustion engine, which is equipped, for example, with direct injection. Under the charging is the supply of the internal combustion engine, in particular their combustion chambers to understand with compressed air, the charge can be done for example by means of at least one exhaust gas turbocharger.

In addition, the desire is great, the compression ratio of the internal combustion engine, in particular the gasoline engine, which has a direct influence on the efficiency of the internal combustion engine, as high as possible. So is a compression ratio of ε = 10: 1 for a supercharged in-line four-cylinder gasoline engine with a specific power of 100 kilowatts per liter of displacement today no longer a rarity.

With increasing values for the compression ratio, the specific torque and the specific power of the internal combustion engine, the need for effective cooling measures increases considerably. While a high compression ratio primarily leads to an increased risk of irregular combustion - the so-called knocking combustion or pre-ignition - increases in the current state of the art with the increase of specific torque and specific power needs, a much larger amount of heat from the respective combustion chamber and the Dissipate exhaust gas. From the resulting premise to maximize heat dissipation to represent high engine loads, there is a conflict of objectives to the above-mentioned endeavor to minimize heat dissipation during start-up and warm-up phases.

Current gasoline engines have a thermal management system that optimizes the start-up and warm-up phase and includes technologies for controlling the cooling water heat flow, an optimized application for cold start purposes and many other measures. Another way to minimize the heat dissipation of the internal combustion engine, the so-called air gap-insulated manifold (LSI) is, which is also referred to as an air gap-insulated exhaust manifold. Such an air gap insulated manifold is for example the DE 103 57 125 A1 to be known as known. To maximize the heat dissipation is in internal combustion engines, in particular gasoline engines - especially with high specific power - a variety of ways known. On the one hand, in this regard, a heat exchanger, which is traversed by the compressed combustion air and this thus withdraws heat known. The latter is then discharged from the heat exchanger directly to the environment or to a cooling medium flowing through the heat exchanger of a low-temperature circuit. It is therefore distinguished between the so-called direct and indirect charge air cooling. The cooling of the combustion air reduces the risk of irregular combustion and thus allows an increase in the compression ratio. Due to the available space and the transmittable amount of heat, the heat dissipation by means of intercooler, however, limits.

On the other hand, the engine cooling system still has considerable potential for heat dissipation, especially at high engine power. In addition to optimizing the flow around the respective, for example, designed as a cylinder combustion chamber with cooling water and improved heat dissipation to the environment, for example, cooled valve seat rings - especially on the outlet side of the combustion chamber - for example DE 101 225 81 A1 or DE 43 28 904 A1 to be known as known.

Another possibility for heat dissipation is the cooling of the turbines of the exhaust gas turbocharger by means of a liquid, such as the example DE 20 2014 104 463 U1 to be known as known.

Furthermore, it is possible to use the comparatively large area of the exhaust manifold for heat dissipation. One possibility represents the integration of the exhaust manifold in the cylinder head of the internal combustion engine, so that the heat removed from the exhaust gas is supplied to the engine cooling water circuit. This approach is for example from the DE 10 2010 024 319 A1 known. A similar possibility is the flow around the exhaust manifold with cooling water through a device suitable for this purpose. The water-cooled exhaust manifold is, for example, the DE 10 2013 006 527 A1 to be known as known.

All of the abovementioned solutions for heat removal are characterized by the fact that the very high possible heat dissipation results in a conflict of objectives with the abovementioned reduced heat dissipation in the starting and warm-up phase of the internal combustion engine.

Of the DE 10 2014 018 318 A1 an exhaust manifold for an exhaust system of a motor vehicle is to be taken as known. The exhaust manifold has an air gap, which can be traversed as needed with air and thus allows heat dissipation at high engine load and at the same time brings no negative impact on the start and warm-up phase of the engine with it. A disadvantage, however, is that the heat dissipatable amount due to the flow of air, which has a relatively low specific heat capacity, is significantly lower than that of an exhaust manifold flowed around with cooling water. Consequently, the effort to increase the air flow is enormous.

In order to prevent the exceeding of the component-specific limit temperatures at high loads, despite the use of various cooling measures, today is an enrichment of the fuel-air mixture common practice. Due to the lack of oxygen, the additionally injected fuel for cooling purposes leads to increased pollutant emissions, which are to be regarded as critical, in particular by the future exhaust gas legislation (real driving emissions). One way to reduce the accumulation is the use of higher quality materials.

Another very effective way to cool the combustion air and to lower the process temperature - and thus the exhaust gas temperature - represents the injection of a cooling medium in the compressed combustion air. By this, basically already known measure of the combustion air by the high specific heat capacity and evaporation the cooling medium, which is for example formed as a liquid, heat removed. In addition to reducing the risk of knocking combustion can also respond to any Vorentflammungen or be prevented, as for example in the DE 10 2012 207 904 A1 is described. All currently known water injection systems have in common that the combustion chamber water must be supplied, which can have a negative impact on the durability of many components of the engine. In addition, corrosion may occur or a dilution of the engine oil may occur, which may cause further consequential damage. In addition, the durability of water injection systems for use in motor vehicles, especially passenger cars, has not been established. Furthermore, the provision of a sufficient amount of water is a major challenge.

Object of the present invention is therefore to provide an exhaust manifold of the type mentioned above and a method for operating such Abgaskrümmers, so that the above-mentioned conflict between the achievement of adequate heat dissipation and the realization of an advantageous and in particular short start and warm-up phase solved can be.

This object is achieved by an exhaust manifold having the features of patent claim 1 and by a method having the features of patent claim 5. Advantageous embodiments with expedient developments of the invention are specified in the remaining claims.

To further develop an exhaust manifold specified in the preamble of claim 1 type such that the initially described conflict between the realization of an advantageous heat dissipation, in particular from the exhaust gas of the internal combustion engine, and the realization of a particularly advantageous and especially very short start and warm-up phase of the internal combustion engine solve is According to the invention at least one injection element provided by means of which at least a portion of the surface with a cooling liquid for cooling the guide member is at least indirectly acted upon. As a result of the cooling of the guide element, the exhaust gas flowing through the guide element can also be cooled as a result of a heat transfer to the guide element and, for example, further from the guide element to the cooling fluid, so that the exhaust gas can be cooled effectively and efficiently.

Through the use of the injection element is an on-demand cooling of the guide element and the exhaust gas can be displayed, as the guide element - in contrast to a permanent liquid cooling of the guide element - is not permanently in contact with the cooling liquid, but the guide element, for example, only temporarily cooled by means of the cooling liquid become. This means that, for example, during a first time period the pressurization of the guide element, in particular its surface, caused by the injection element can be omitted with the cooling fluid, so that the guide element, in particular the surface, is in contact only with the air surrounding the surface. As a result, excessive heat dissipation from the guide element and from the exhaust gas can be avoided, so that the guide element and, for example, other components arranged in an exhaust system of the internal combustion engine can be heated particularly quickly. As a result, the starting and warm-up phase of the internal combustion engine can be kept particularly short. During a second period of time different from the first time span, for example, the guide element, in particular its surface, can be acted on by the cooling element by means of the injection element, so that the surface is wetted with the cooling fluid. In this way, a particularly high amount of heat can be removed from the guide element and the exhaust gas, so that excessive temperatures of the guide element and in particular of the exhaust gas and thus excessive temperatures of other, arranged in the exhaust system components can be avoided.

In order to realize this demand-responsive action on the surface of the guide element, the injection element comprises, for example, at least one ejection opening, via which the cooling liquid can be ejected from the injection element. The ejection opening is associated, for example, at least one closing element, which is movable between a closing position fluidically blocking the ejection opening and at least one open position releasing the ejection opening-in particular relative to a housing of the injection element. For moving the closing element, which is also referred to as a valve element, the injection element comprises, for example, an actuator, by means of which the closing element is movable. The actuator is, for example, electrically and / or hydraulically and / or pneumatically movable and, for example, as a magnet, in particular electromagnet, be formed, so that the injection element is formed for example as a solenoid valve.

In particular, by means of the injection element, it is possible to displace the air in contact with the surface, which surrounds the surface, for example, with the cooling liquid, so that, for example, a fine spray forms which contacts the surface or the surface in contact with the surface Surface surrounding air and the ejected from the injection element coolant comprises. By means of this fine spray, the surface and thus the guide element and the exhaust gas flowing through the guide element can be cooled particularly well and effectively.

In other words, can be effectively cooled by the use of the injection element, the guide element or the exhaust manifold as a whole, so that excessively high exhaust gas temperatures of the internal combustion engine can be avoided. The cooling of the exhaust gas takes place, for example, by a heat transfer from the exhaust gas flowing through the guide element to the guide element and further from the guide element to the cooling liquid, which contacts the surface as a result of the action of the guide element, in particular the surface. In this case, the cooling liquid has a significantly higher heat transfer coefficient than the air, so that effective cooling of the guide element and thus of the exhaust gas can be realized by subjecting the surface to the cooling liquid. If there is no application of the coolant to the surface, no or only little heat transfer takes place from the guide element to the air surrounding or flowing around the guide element, so that excessive cooling of the exhaust gas flowing through the guide element is also avoided. As a result, the starting and warm-up phase of the internal combustion engine can be kept particularly short, so that the internal combustion engine can be brought to an advantageous operating temperature in a particularly short time. This can be realized in a particularly efficient and therefore low-efficiency or fuel consumption and CO ₂ emission-poor operation.

The idea underlying the invention is a demand-based heat removal from the exhaust gas To realize over the surface of the guide element by the surrounding or surrounding the guide element air is supplied with the cooling liquid or humidified. This is done in such a way that the coolant can be introduced into the air by means of the injection element. The coolant is, for example, water, so that a particularly effective cooling can be realized. The comparatively high specific heat capacity and the high heat of vaporization of the cooling liquid lead to a significantly improved cooling effect compared to the air.

The injection element is also referred to as Gemischbildner, which - as described above - which has at least one or more ejection openings, in particular in the form of fine nozzles. By means of the ejection opening, the cooling liquid is ejected, in particular in the vicinity of the guide element, and in particular under pressure in the direction of the guide element and thereby atomized, for example. This creates, for example, a fine spray, in particular a fine spray of water. Due to the evaporation of the fine spray, in particular on the surface of the guide element, the guide element is deprived of a large amount of heat, which leads to a significant reduction in the temperature of the exhaust gas.

In particular, it is conceivable that the exhaust manifold is designed as an air gap-insulated manifold (LSI), as for example in the DE 103 57 125 A1 whose contents are to be considered in full as part of this disclosure. In this case, the exhaust manifold on at least one housing element which surrounds at least a portion of the guide element and is at least spaced from the portion, whereby between the guide member and the housing member by the guide member and the housing member each at least partially defined gap is arranged. The gap is limited, for example, on the one hand by the guide element and on the other hand by the housing element, wherein the gap is limited on the one hand in particular by the surface of the guide element. In this case, the gap of the aforementioned air can be flowed through, as for example in the DE 10 2014 018 318 A1 whose contents are to be considered in full as part of this disclosure.

It is provided in the context of the invention, the air flowing through the gap, which is also referred to as an air gap, flowing air by means of the injection element with the cooling liquid by means of the injection element, the cooling liquid is introduced into the air. It is provided in particular that the air is applied to the cooling liquid before it enters the air gap. In other words, the liquid can be introduced at least one point arranged upstream of the gap into the air to be supplied to the gap by means of the injection element, so that the air is already mixed with the cooling liquid before it enters the air gap. As a result, the cooling fluid supplied to the air flow and formed, for example, as water significantly increases the amount of heat which can be dissipated to reduce the exhaust gas temperature.

Due to the fact that the coolant formed for example as water does not penetrate into combustion chambers of the internal combustion engine, the demands on the quality of the cooling liquid in comparison to conventional water injection systems are very low. Consequently, the used cooling liquid does not necessarily have to be demineralized or distilled water. Rather, even the use of rainwater, in particular filtered rainwater, as the cooling liquid conceivable, the rainwater can be collected during rainfall of the body of a comprehensive exhaust manifold invention and collected in a tank.

The invention also includes a method for operating an exhaust manifold according to the invention. Advantages and advantageous embodiments of the exhaust manifold according to the invention are to be regarded as advantages and advantageous embodiments of the method according to the invention and vice versa. In the context of the method, the cooling liquid is introduced by means of the injection element in the contact with the surface or the air flowing around the surface, thereby realizing an appropriate cooling of the guide element and the exhaust gas.

Further advantages, features and details of the invention will become apparent from the following description of preferred embodiments and from the drawing. The features and feature combinations mentioned above in the description as well as the features and feature combinations mentioned below in the description of the figures and / or shown alone in the figures can be used not only in the respectively specified combination but also in other combinations or in isolation, without the scope of To leave invention.

The drawing shows in:

1 a schematic representation of an internal combustion engine according to a first embodiment of a vehicle, with at least one injection element, by means of which at least a portion of a surface of a Exhaust manifold with a cooling liquid for cooling the exhaust manifold is at least indirectly acted upon; and

2 a schematic representation of the internal combustion engine according to a second embodiment.

In the figures, the same or functionally identical elements are provided with the same reference numerals.

1 shows one as a whole 10 designated internal combustion engine according to a first embodiment of a vehicle in the form of a motor vehicle, in particular a passenger car. The internal combustion engine 10 is also referred to as an internal combustion engine and is designed for example as a gasoline engine. The internal combustion engine 10 has a cylinder housing 12 on, by which at least one as a cylinder 14 trained combustion chamber is formed. Out 1 is seen that in this case by the cylinder housing 12 a plurality of cylinders 14 is formed. The respective cylinder 14 is an injection element 16 assigned, which is also referred to as Gemischbildner. By means of the injection element 16 is a fuel, in particular a liquid fuel, for operating the internal combustion engine 10 in the respectively assigned cylinder 14 , in particular directly, can be introduced, in particular injectable.

During its operation, the internal combustion engine sucks 10 Air on, which is an intake 18 the internal combustion engine 10 flows through. By means of the intake tract 18 the air gets into the cylinders 14 directed. It is in the intake 18 an air filter 20 arranged, by means of which the intake tract 18 air flowing through is filtered. The intake tract 18 air flowing through is in 1 through an arrow 22 illustrated.

The internal combustion engine 10 is designed as a supercharged internal combustion engine and for this purpose comprises at least one exhaust gas turbocharger 24 , which one in the intake tract 18 arranged compressor 26 includes. By means of the compressor 26 the air is compressed, so the cylinders 14 can be supplied with the compressed air. This is also called charging, so the internal combustion engine 10 is designed as a supercharged internal combustion engine. By compressing the air, it is heated. Nevertheless, to realize a particularly high degree of supercharging, is in the intake 18 downstream of the compressor 26 a cooling device in the form of a charge air cooler 28 arranged, by means of which the compressed and thus heated air is cooled.

The compressed and cooled air can enter the cylinders 14 inflow, so that in the respective cylinders 14 a fuel-air mixture is formed. This respective fuel-air mixture is burned, resulting in exhaust gas of the internal combustion engine 10 results. The exhaust gas can be from the cylinders 14 off and into an exhaust tract 30 the internal combustion engine 10 pour in, leaving the exhaust tract 30 can be flowed through by the exhaust gas. In the exhaust tract 30 is a turbine 32 the exhaust gas turbocharger 24 arranged. The turbine 32 is driven by the exhaust gas, wherein the compressor 26 from the turbine 32 is drivable. As a result, energy contained in the exhaust gas can be used to compress the air, so that a particularly efficient and thus fuel-efficient operation of the internal combustion engine 10 is feasible.

The particular compressed air is also referred to as combustion air, which by means of the intercooler 28 Heat is extracted before the combustion air in the intake tract 18 downstream of the intercooler 28 arranged throttle 34 flows through and finally the cylinders 14 is supplied.

After the combustion of the respective fuel-air mixture, the exhaust gas of each cylinder 14 pushed out and the turbine 32 fed. Thus, it comes to an arrow 36 illustrated exhaust gas mass flow, which the exhaust tract 30 flows through. The exhaust gas mass flow is finally discharged into the open, after the exhaust gas mass flow an exhaust aftertreatment device 38 the exhaust tract 30 flowed through. The exhaust tract 30 is also referred to as exhaust system and serves to guide the exhaust gas.

In the exhaust tract 30 is a whole with 40 designated exhaust manifold of the internal combustion engine 10 arranged. The exhaust manifold 40 includes at least one guide element 42 , which at least one in 1 not shown and with the cylinders 14 fluidly connected and consequently from the exhaust gas from the cylinders 14 permeable exhaust gas channel and a side facing away from the exhaust gas, outside and contactable with air surface 44 having. This means that air is the surface 44 can contact and flow around, for example.

In order to realize on the one hand a particularly effective cooling of the exhaust gas and thus excessive temperatures of the exhaust tract 30 to avoid and on the other hand, the start and warm-up phase of the internal combustion engine 10 To keep particularly short is at least one injection element 46 provided by means of which at least a portion of the outside surface 44 with a cooling liquid present in the form of water 48 at least indirectly acted upon. As will be explained below, it is in the first embodiment provided that by means of the injection element 46 the the surface 44 surrounding or contacting air with the water 48 from a reservoir formed, for example, as a tank 50 can be moistened. For this purpose, the injection element 46 over at least one line 52 fluidic with the reservoir 50 connected, so the water 48 from the reservoir 50 over the line 52 to the injection element 46 can be performed. The water 48 is in the reservoir 50 taken, which at least partially with the water 48 is filled.

The injection element 46 is for example an injection nozzle, which does not necessarily have to be electrically controllable. In the line 52 is present a pump 54 arranged, by means of which the water 48 from the reservoir 50 to the injection element 46 can be promoted or promoted.

The injection element 46 has at least one, for example, in overlap with the surface 44 arranged ejection opening, via which via the line 52 to the injection element 46 guided water 48 from the injection element 46 sprayed out and especially against the surface 44 can be sprayed. By spraying out the water 48 from the injection element 46 forms a fine spray 56 , In other words, the water becomes 48 by means of the injection element 46 in the direction of the guide element 42 and in particular the surface 44 to the fine spray 56 atomized. Alternatively to the pump designed as a pump 54 the use of a pressure intensifier is conceivable.

2 shows a second embodiment of the internal combustion engine 10 , The second embodiment differs in particular from the first embodiment that the exhaust manifold 40 is designed as an air gap insulated manifold (LSI). In this case, the exhaust manifold comprises 40 a housing element 58 which at least a portion of the guide element 42 surrounds and is spaced from the portion, whereby between the guide element 42 and the housing element 58 at least a gap 60 is arranged, which - as in 2 through arrows 62 illustrated - is traversed by air. For example, the air gets into the gap 60 promoted. The moisture content of the gap 60 air flowing through can by the means of the injection element 46 cause fine mist 56 in the present case before entering the gap 60 be significantly increased. This means that the water 48 by means of the injection element 46 upstream of the gap 60 in the gap 60 flowing air is introduced. The moist air flows through the exhaust manifold 40 or the gap 60 and increases the possible heat dissipation to reduce the exhaust gas temperature.

In the internal combustion engine 10 is thus a significant reduction of the exhaust gas temperatures in operating areas of high engine load without negative effects on the start and warm-up phase of the internal combustion engine 10 realizable. The resulting by the significant increase in heat dissipation, primary advantage is the sinking or omitting need for enrichment of the fuel-air mixture with fuel for component protection reasons. This results in a significant reduction in pollutant emissions and fuel consumption - and thus CO ₂ emissions. In addition, internal combustion engines can be developed with a further increase in specific power and therefore the downsizing for CO ₂ emissions can be continued. Furthermore, there are the following advantages: low heat input into the engine cooling water, which among other things leads to the relief of the cooling system; Reduction or elimination of fuel enrichment for component protection at high loads and thus reduction of fuel consumption; Reduction of pollutant emissions; and potential for further downsizing to reduce CO ₂ emissions.

LIST OF REFERENCE NUMBERS

10

Internal combustion engine

12

cylinder housing

14

cylinder

16

Injector

18

intake system

20

air filter

22

arrow

24

turbocharger

26

compressor

28

Intercooler

30

exhaust tract

32

turbine

34

throttle

36

arrow

38

exhaust treatment device

40

exhaust manifold

42

guide element

44

surface

46

Injector

48

water

50

reservoir

52

management

54

pump

56

spray

58

housing element

60

gap

62

arrow

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 102005062186 A1 [0002]
• WO 2011/045659 A1 [0003]
• DE 10357125 A1 [0008, 0025]
• DE 10122581 A1 [0009]
• DE 4328904 A1 [0009]
• DE 202014104463 U1 [0010]
• DE 102010024319 A1 [0011]
• DE 102013006527 A1 [0011]
• DE 102014018318 A1 [0013, 0025]
• DE 102012207904 A1 [0015]

Claims (5)

Exhaust manifold ( 40 ) for an internal combustion engine ( 10 ), with at least one guide element ( 42 ), which at least one with at least one combustion chamber ( 14 ) of the internal combustion engine ( 10 ) fluidly connectable and exhaust gas from the combustion chamber ( 14 ) through-flowable exhaust gas channel and a side facing away from the exhaust gas channel, outside and contactable with air surface ( 44 ), characterized in that at least one injection element ( 46 ) is provided, by means of which at least a portion of the surface ( 44 ) with a cooling liquid ( 48 ) for cooling the guide element ( 42 ) is at least indirectly acted upon. Exhaust manifold ( 40 ) according to claim 1, characterized in that the injection element ( 46 ) at least one in overlap with the surface ( 44 ) arranged ejection opening for spraying the cooling liquid ( 48 ) from the injection element ( 46 ) and against the surface ( 44 ) having. Exhaust manifold ( 40 ) according to claim 1 or 2, characterized in that the exhaust manifold ( 40 ) is designed as an air gap-insulated exhaust manifold and at least one housing element ( 58 ), which at least a portion of the guide element ( 42 ) and spaced from the sub-area, whereby between the guide element ( 42 ) and the housing element ( 58 ) A gap ( 60 ) is arranged, which can be traversed by the air. Exhaust manifold ( 40 ) according to claim 3, characterized in that the liquid ( 48 ) at least one upstream of the gap ( 60 ) arranged by means of the injection element ( 46 ) into the gap ( 60 ) supplied air can be introduced. Method for operating an exhaust manifold ( 40 ) according to any one of the preceding claims.

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