EP1196687B1 - Fluid feed duct for a hot fluid in a hollow structure - Google Patents

Abstract

A fluid feed duct, which may be used for feeding a stream of recirculated exhaust gas into a stream of intake air for an internal combustion engine. The feed duct includes a hollow structure (10) into which a feed connection (12) is introduced via a joint structure (34). A ceramic pipe (16) is used to prevent heat from the exhaust gas stream from being conducted to mounts in the hollow structure (10) which represents the intake duct of the engine. Consequently, the intake duct can be manufactured of a thermoplastic synthetic resin material, since the risk of thermal overstressing is avoided. The feed connection also has a deflecting segment (19) which is provided in its sides with outlet openings (20). This enables the exhaust gas to be introduced in the direction of flow of the intake air, so that optimal mixing is assured and the hot exhaust gas stream is prevented from passing directly to the wall of the thermoplastic intake duct, thereby preventing the intake duct from being melted.

Description

State of the art

The invention relates to a fluid introduction, in particular as exhaust gas recirculation in the intake tract of an internal combustion engine can be used, according to the genus of claim 1.

The recirculation of exhaust gases into the intake tract of an internal combustion engine is known. This measure is taken to the pollutant emission of the internal combustion engine to reduce. The problem here, however, is the high temperature of Exhaust gas. In particular, if the intake is made of plastic, so can the introduction of the exhaust gas to a melting of the intake in the area lead the exhaust gas supply.

In order to prevent thermal over-utilization of the intake tract is according to EP 486 338 A1 proposed to carry out the exhaust gas introduction double-walled. The exhaust gas is introduced through the inner tube into the intake tract, wherein the between the double wall resulting cavity insulating against the contact point the exhaust gas inlet with the suction pipe acts.

In order to achieve an additional cooling effect, the intermediate space becomes a part passed the sucked fresh air, which is taken before a throttle and passes through a bypass line in the intermediate space. The cooling air passes through corresponding openings parallel to the exhaust gas flow back into the intake.

In the proposed solution, however, the proportion of recirculated exhaust gas can be do not arbitrarily increase in proportion to the conducted combustion air. The double-walled tube is directly connected to the suction tube, so that at higher Return rates nevertheless the risk of melting the wall of the intake tract threatens. In addition, the hot exhaust gas flow hits unhindered on the opposite Wall of the intake tract, whereby also here a range of high thermal Stress arises, which can lead to a component failure.

To prevent this, according to the construction according to EP 886 063 A2 a thermally resilient gas guide element 26 (see Figure 2) is provided be the wall of the intake tract from a direct impact protects the hot exhaust gas flow. Within this gas guide element has the hot exhaust gas flow enough time to mix with the intake air. however means such an additional component increased design complexity and also increases the weight of the intake tract. Both are in terms of one possible high efficiency in the manufacture and use of the intake system not wished.

In order to avoid the mentioned disadvantages, in the automotive technical journal, Vintage 1992, page 530 an attachment of hot pipes to plastic components proposed. This also consists of a double-walled Pipe, however, wherein the inner tube ends earlier than the outer tube. This will achieved the effect of a suction jet pump, so that cooling air from the intake can be sucked through the space of the double-walled tube. hereby So not only the inlet is cooled, but the cooling air mixed at the same time with the exhaust gas flow and thereby leads to a cooling of the same.

However, in this embodiment of the exhaust gas recirculation are the feasible Exhaust gas recirculation rates limited to the top. To allow the cooling gas flow must be attached to the exhaust gas recirculation pipe a cuff, which directly merges into the mounting flange for the exhaust gas inlet at the intake manifold. These Thermal bridge leads at high exhaust gas recirculation rates to a high thermal Load on the intake tract in the area of exhaust gas recirculation. Also, the exhaust gas flow Although cooled. However, if a certain exhaust gas recirculation rate is exceeded, so must in the intake system, a gas guide element according to EP 886 063 A2 be provided.

The document US 5,207,714 discloses an exhaust gas recirculation device which in an intake tract is integrated. The exhaust gas recirculation device has a Channel in which air is passed to the internal combustion engine. Into this channel protrudes Inlet for exhaust gases into it. The inlet nozzle has openings which the exhaust gas can flow into the intake air.

The document JP 05 25 62 17 discloses an intake system in which a second Fluid can be introduced. For this purpose, an inlet pipe is provided, which in the interior of a fluid line protrudes. Between the supply of the second fluid and the fluid line is arranged an insulation, which is a heat transfer from prevents the supply of the second fluid to the fluid line.

The object of the invention is therefore, a fluid introduction of hot fluids in one Cavity structure for the passage of a cooler fluid to create, the cost-effective is in the production and a high rate of introduced hot fluid in Relative to the passage of fluid allowed, the thermal load of the Cavity structure is kept within the required limits.

This object is solved by the features of claim 1.

Advantages of the invention

The inventive solution for the fluid introduction therefore provides the inlet in the End region, which extends into the interior of the cavity structure, with outlet openings to be provided in the direction of the flow direction of the passed fluid point. By this constructive measure, the flow of the fluid to be introduced redirected towards the flow in the cavity structure, creating a direct Impact of the introduced fluid flow on a wall of the cavity structure is prevented. The fluid to be introduced is taking advantage of the Saugstrahlpumpeneffektes detected and carried along by the flow of the fluid passed through, whereby a rapid mixing takes place. The mixing effect at the same time a cooling of the fluid to be introduced and a heating of the to be passed through fluids. The resulting temperature, however, is in the range of permissible thermal load of the cavity wall.

The outlet openings are along the flanks at the end portion of the inlet nozzle arranged. The variety of openings improves the mixing effect, since the fluid flow of the fluid to be introduced broken into many small streams becomes.

According to the invention, the outlet openings with Provided baffle plates. In particular, if the inlet nozzle made of sheet metal is, these baffles can be produced in a simple manner by punching. Prefers the baffles are bent into the interior of the inlet nozzle and cause so that optimal mixing of the fluid to be introduced with the durchzulei fluid. In addition, the baffles cause an application of the fluid flow to be introduced at the exit to the end portion of the inlet nozzle, creating a direct Wall contact of the fluid to be introduced with the walls of the cavity structure is avoided. This takes place only after a sufficient mixing distance in the further course of the flow to be passed through in the cavity structure.

In order to promote the mixing of the two fluids further, it is advantageous to the Inlet with respect to the flow through in the cavity structure with to provide a flow-optimized outer contour. When flowing around the inlet nozzle then results in a laminar flow along the outer contour of the inlet nozzle, in particular its end region. This will result in the mixing result improved with the fluid to be introduced.

A particularly favorable embodiment for the fluid introduction results when the features of claim 1 and the use of a Einleitstutzens of ceramic be combined. This poses the risk of thermal over-utilization the cavity structure both in the area of the connection to the inlet nozzle and Most largely prevented in the field of fluid-carrying wall parts. Dependent on however, the measures can also be applied individually lead to a satisfactory solution. The design of the end portion of the inlet according to the invention is z. B. not necessary if the fluid supply in a wide cavity takes place, so that the inlet of the opposite wall of the cavity structure is far away. On the contrary, with particularly narrow cavity structures only the measure at the end of the inlet nozzle according to the invention necessary while the Heat conduction at the inlet connection remains uncritical.

A further embodiment of the invention provides that the end region of the inlet is formed by a piece of pipe, which at the flows around with sides Outlets is provided. The cross-section of the pipe section does not have to be circular be. Rather, different cross-sectional shapes are conceivable. The pipe piece can be produced by injection molding. Another possibility is the production of a tubular semi-finished product, which is deflected. The openings must then z. B. are punched. The pipe section will continue with provided with a plug connection, 'and can with its help on the inlet pipe be plugged. This is also a retrofit of this component in already Use of incoming intake systems possible.

According to a further embodiment of the invention, the pipe section is open at the end. This is contrary to a design of the pipe section of a tubular semi-finished product. The open pipe end serves as an additional inlet for the recirculated Exhaust.

An alternative fluid introduction consists of three structural functional areas, the Cavity structure, the inlet nozzle and the connection structure. The cavity structure is suitable for the passage of a fluid and z. B. from an intake pipe for an internal combustion engine. The inlet pipe is to the connection suitable with a feed line to be initiated by the feed line hot fluid is passed. In addition, a connection structure is provided, the on the one hand for fastening the inlet nozzle in the wall of the cavity structure serves and second allows a seal between these two components.

The fluid introduction described must for the occurring thermal loads be designed by the introduction of the hot fluid. This means that the inlet pipe must be temperature resistant to the fluid to be introduced. For However, the cavity structure often come lower melting materials, eg. B. Plastic, used. Since the inlet nozzle by the fluid to be introduced strongly heats up, the junction between this and the cavity structure must Insulated so far that the cavity structures in this area not thermal is overstretched. For this purpose, the connection structure is provided, wherein about this takes place a heat conduction from the inlet pipe to the cavity structure. there arises in the connection structure starting from the inlet to the cavity structure towards a temperature gradient, so that the contact surface between the connection structure and cavity structure is cooler than the inlet nozzle.

Further lowering the temperature in the connection between cavity structure and connecting structure according to the invention is achieved in that means are provided, the heat input from the inlet in the connection structure diminish from the beginning. This naturally also lowers the Heat load of the connection point between connection structure and cavity structure. In comparison, higher exhaust gas recirculation rates can be achieved than at a fluid introduction without the means for reducing the heat input. at Diesel engines are sometimes required exhaust gas recirculation rates up to 60%, which only initiated when using the mentioned means in a suction system made of plastic can be.

According to a useful embodiment of the invention can be used as a means of reduction the heat input of the inlet pipe to be made of ceramic. This Material has a sufficient temperature resistance to the hot to be introduced fluid. Compared to metallic materials, the usual Design material for the inlet port is the thermal conductivity Of ceramic, however, much lower. The Einleitsutzen thus acts as a thermal Insulator, so that a lower amount of heat introduced into the connection structure becomes.

It is also advantageous to produce the connection structure made of ceramic. This will be also in this area prevents excessive heat conduction. Inlet pipe and Connecting structure can be made in one piece, reducing the manufacturing cost advantageously reduced.

A further advantageous embodiment of the means for reducing the heat input consists in a double-walled construction principle of the inlet nozzle. This has an inner wall and an outer wall, wherein in the space of this Walls located fluid acts as an insulator. The fluid to be introduced is through the Passed through the inner wall formed cross section.

To the gap as an insulator also to reduce the introduction of heat energy in the connection structure, this is on the outer wall of the Einleitstutzens attached. The insulating effect of the gap can be increased be when the described embodiment of the invention with that of the Prior art already known Saugstrahlpumpeneffekt is combined. The Fluid in the space is constantly replaced, causing its warming is prevented. Thus, the outer wall remains cooler from the outset, which also reduces the heat input into the connection structure.

According to a modification of the invention, the temperature gradient in the Influence connection structure. This is done by means of enlarging the Surface of the connection structure. As a result, the amount of heat radiation, in proportion to the surface of the connection structure is increased, thereby increasing the connection between the connection structure and cavity structure less heated. To enlarge the surface can z. B. the connection structure made of thin sheet metal, wherein given a bellows-like structure. The wavy walls of this bellows Structure lead to a sufficient stiffening and at the same time enlarge the surface. Another possibility is a bowl-like design the connection structure, with the outer radius of this bowl chosen larger than would be necessary for the installation of the inlet. Also the bowl Can be made of thin sheet metal and stiffened by beading. The beads lead at the same time to a further increase of the surface.

For a large-scale production, the connection structure according to a appropriate training of the inventive idea manufactured as a bayonet lock. It thus creates a module, which is easily incorporated into cavity structures can be. In particular, if these are made of plastic, can be the corresponding Recording as a counterpart of the bayonet catch simply in the wall structure integrate. Einleitstutzen and connection structure kann.dann as a standard component be executed, which can be achieved in high quantities. This leads to an increased efficiency of the solution. Through the bayonet lock the fluid introduction can be easily mounted, whereby the reduced installation costs contributes to a further increase in the efficiency of fluid introduction.

The described embodiments are suitable for the thermal load of To reduce connection between inlet and cavity structure, so that in Relative to the passage of fluid through a higher amount of einzuleitendem hot Fluid can be mixed. In the case of application as exhaust gas recirculation This means higher limits for the exhaust gas recirculation rates in the sucked Combustion air. However, this not only means a higher thermal load the joints, but also the remaining cavity structure, since the in the cavity located recirculated fluid cools on the cavity walls. Therefore, even in these areas, the limits of thermal capacity the cavity structure are exceeded. This is especially the case when the recirculated fluid flow unhindered against a wall of the cavity structure can.

drawing

Figur 1

eine Fluideinleitung im Längsschnitt bestehend aus einem Ansaugrohr, in das ein doppelwandiger Einlaßstutzen mit abgewinkeltem Endbereich hineinreicht,

Figur 2

den Schnitt A-A gemäß Figur 1,

Figur 3

eine Fluideinleitung mit einem Einleitstutzen aus Keramik im Längsschnitt, welche nicht Gegenstand der Erfindung ist und

Figur 4

eine Fluideinleitung entsprechend Figur 1, die sich jedoch in einer schrägen Anordnung der Austrittsöffnungen und in der Gestaltung der Verbindungsstruktur unterscheiden, im Längsschnitt,

Figur 5

die Aufsicht auf den Einleitstutzen von hinten, der im Ansaugrohr montiert ist und

Figur 6

ein Detail des Bajonettverschlußes der Fluideinleitung gemäß Figur 4 und 5

Figur 7

einen als Rohrstück ausgeführten Endbereich der Fluideinleitung im Schnitt und

Figur 8

die Aufsicht m gemäß Figur 7 auf das Rohrstück.

Further details of the invention are described in the drawings with reference to schematic embodiments. Show here

FIG. 1

a fluid inlet in longitudinal section consisting of an intake pipe into which a double-walled inlet nozzle with an angled end region extends,

FIG. 2

the section AA according to FIG. 1,

FIG. 3

a fluid inlet with an inlet nozzle made of ceramic in longitudinal section, which is not the subject of the invention and

FIG. 4

1, which, however, differ in an oblique arrangement of the outlet openings and in the design of the connecting structure, in longitudinal section,

FIG. 5

the supervision of the inlet pipe from the rear, which is mounted in the intake pipe and

FIG. 6

a detail of the bayonet closure of the fluid inlet according to Figures 4 and 5

FIG. 7

an executed as a pipe section end portion of the fluid inlet in section and

FIG. 8

the supervision m according to Figure 7 on the pipe section.

Description of the embodiments

The fluid inlet according to FIG. 1 provides exhaust gas recirculation into the intake tract an internal combustion engine. A cavity structure 10 is as a line section of Intake tract executed. This cavity structure has an installation opening 11, through which an inlet connection 12 is pushed into an interior 13 of the cavity structure can be. The breaklines are as inlet 14 and 15 as outlet understand, so that combustion air according to the indicated solid Arrows can flow through the cavity structure.

The inlet connection 12 consists of a connection 16 for an exhaust gas recirculation line, this formed by an outer tube 17, a double-walled tube structure becomes. An associated inner tube 18 is for guiding the exhaust gas, represented by a dashed arrow provided. The inner tube 18 opens into an end region 19 of the inlet 12, and has outlet openings 20 for the introduction of the exhaust gas in the air flow of the cavity structure. The introduction of the exhaust gas is indicated by dashed arrows. With the outer tube 17 is firmly connected a metal bellows 21, which connects the inlet nozzle 12 with the cavity structure 10 allows. As part of the cavity structure is in this context also understood a cover 22 which is fixed with screws 23 and with the help of an O-ring 24 is sealed. An outer edge 25 of the Blechbalgs is with a Teflon ring 26, which in turn is injected into the lid 22. The teflon ring points towards the lid on a higher temperature resistance, so that a certain Introduction of heat through the bellows the overall device is not damaged. An inner edge 27 of the metal bellows 21 is connected directly to the outer tube 17 z. B. connected by soldering.

For fixing the inner tube 18 in the outer tube 17 has first bead 28, which with the outer walls of the inner tube 18 are in communication. One through inner tube and outer tube formed annular space 29 is in addition to its insulating effect at the same time used for the passage of intake air. This is by a Suction jet pump effect at the inner tube end 30 sucked through the annular space 29, in she has previously entered through inlet holes 31. On the way to the inlet holes In addition, the intake air can cool the inner sides of the metal bellows. The path of the cooling air flow is indicated by dotted arrows.

The structure of the end portion 19 can be seen in FIG. This forms one elongated cavity defined by the flow in the cavity structure 10th is flown around (solid arrows). The cavity 45 faces the interior 13 as a connection to the outlet openings 20, through which the exhaust gas flow (dashed Arrows) can be initiated in the direction of the flow of intake air. The exhaust gas flow is initially still on flanks 32 of the end portion 19, then to Gradually to mix with the flow of intake air. The end area is made of sheet metal. The openings can be easily produced by the material is unlatched and bent inwards. This creates baffles 33, which facilitate an undisturbed outlet of the exhaust gas through the outlet opening 20.

FIG. 3 shows a two-part inlet pipe 12. The first part is the end portion 19, which is executed according to Figure 1. This one is directly with a ceramic component connected, which the functions of the terminal 16 and a connection plate 34 for mounting in the cavity structure 10 united. The ceramic Material of this component acts as an insulator, so that the heat from the introduced Exhaust gas (dashed arrow) only slightly to the cavity structure 10 is passed.

The inlet pipe 12 is on the ceramic plate directly into the mounting hole 11 of Molded cavity 10. This results in an easy to produce Unit. The geometry of the inlet is through the two-part construction very easy. The inlet nozzle can in appropriate recordings in the casting tool be fixed to the injection molding process of the cavity structure directly injected to become. The effort of a final assembly is therefore completely eliminated.

The inlet connection 12 according to FIG. 4 has the same design as that shown in FIG Example, a double-walled structure consisting of inner tube 18 and outer tube 17, up. However, this is not a cooling air flow (comparisons dotted Arrow in Figure 1) flows through. The gas in the annular space 29 is therefore not constantly replaced and still acts as an insulator between outdoor and Inner tube.

On the outer tube 17, a sheet metal bell 35 is attached, which is used to attach the inlet 12 on the cavity structure 10 is used. The sealing takes place via an O-ring 24a between the bell 35 and installation hole 11. To stiffen the is Sheet bell 35 provided with beads 28a.

In contrast to the other embodiments, the outlet openings 20 arranged at an angle. This measure serves the direction correction, the exiting Exhaust gas flow in the direction of the flowing intake air in the cavity structure. The exhaust gas flow is. Due to the deflection in the end portion 19 namely with a Twisted. To contact the exhaust gas flow with the cavity walls to avoid as long as possible after exiting the end, the swirl pulse destroyed by means of the obliquely arranged baffles in the outlet openings 20. This process is indicated by the dashed arrows.

The connection between the sheet metal bell 35 and cavity structure 10 is effected by a Bayonet closure 36, whose operation is best with the help of Figure 4 and 5 can be understood. Around the mounting hole 11 are on the cavity structure 10 receiving ribs 37 are arranged. These have slots 38 in which, by rotation of the inlet 12, a radially on the outer circumference of the Sheet metal bell 35 arranged tab 39 slips in, whereby the sheet bell 35th is pressed on the O-ring 24a. The receiving ribs 37 are on a mounting flange 40 attached, which adjoins the mounting hole 11 and through Support ribs 41 is stabilized toward the cavity structure. It becomes the flow optimized Shape of the end area clearly.

FIG. 5 also shows the contour of the end region 19, which is the one of FIG in the interior 13 projecting part of the Einleitstutzens 12 represents. The view in the Interior 13 takes place in the flow direction of the intake air (see solid Arrow in Figure 4).

FIG. 6 shows a section of the plan view of the inlet connection in the direction of the introduced exhaust gas (compare dashed arrow in Figure 4). This is recognizable Inner tube 18, the terminal 16, one of the beads 28a in the bell jaw 35, the edges the tab 39, which is pushed under the receiving ribs 37, and a lock 42, which consists of a recess 43 between the receiving ribs 37, in which a protruding sheet metal tongue 44 snaps, which is part of the tab 39. Farther let the ends of the baffles 33 inside the tube recognize.

Figures 7 and 8 show an alternative inlet nozzle 12, in a not shown in detail Suction system extends in the flow direction of the sucked air. On this is with the help of a connector 43 a pipe socket 42 inserted, the End region of the inlet nozzle forms. The outlet openings 20 are in the pipe section, which is made of a tubular semi-finished, pressed in, wherein This results in baffles 33 in the form of tongues. The end of the pipe section 42 is open, so that through this opening the recirculated exhaust gas into the intake can be initiated.

LIST OF REFERENCE NUMBERS

10

cavity structure

11

hole

12

feed connection

13

inner space

14

Inlet

15

outlet

16

Connection

17

outer tube

18

inner tube

19

end

20

outlet openings

21

Blechbalg

22

cover

23

screw

24,24a

O-ring

25

outer edge

26

Teflon ring

27

inner edge

28,28a

Beading

29

annulus

30

Inner tube end

31

inlet bore

32

flank

33

baffle

34

connecting plate

35

Tin bell

36

bayonet

37

receiving ribs

38

slot

39

flap

40

receiving flange

41

supporting rib

42

Arrettierung

43

Aussparrung

44

sheet metal tongue

45

cavity

Claims (5)

1. Fluid feed duct, more especially for recirculation of exhaust gas into the intake tract of an internal combustion engine, said fluid feed duct comprising

   a hollow structure (10) for conducting a fluid from an inlet (14) to an outlet (15),

   a feed connection (12) for feeding a fluid, which is hotter than the conducted fluid, into the hollow structure,

   a connecting structure (21, 34, 35) for mounting the feed connection in the hollow structure in a sealed manner,

   wherein the feed connection and the connecting structure have a higher thermal resistance than the hollow structure and the feed connection is thermally resistant to the fluid to be introduced, wherein an end region (19) of the feed connection points in the direction of the flow of the conducted fluid and outlet openings (20) into the interior (13) of the hollow structure are provided on the flanks of the end region, which are flowed around by the fluid, characterised in that the outlet openings (20) include baffles for influencing the direction of flow of the introduced fluid.
2. Fluid feed duct according to claim 1, characterised in that in the region in which it protrudes into the interior (13) of the hollow structure (10), the feed connection (12) includes a outer contour which is configured to optimise the flow conducted through it.
3. Fluid feed duct according to claim 1, characterised in that the end region of the feed connection is produced from a pipe segment (42), which is mounted on the feed connection by means of a plug connection (43).
4. Fluid feed duct according to claim 3, characterised in that the end of the pipe segment is open.
5. Fluid feed duct according to one of the preceding claims, characterised in that the connecting structure (35) is connected to the hollow structure by a bayonet closure (36).

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