EP2402585B1 - Device for recirculating exhaust gas for an internal combustion engine - Google Patents

Description

The invention relates to a device for exhaust gas recirculation for an internal combustion engine according to the preamble of claim 1.

The recirculation of exhaust gas of an internal combustion engine, for example, to reduce pollutants is common in commercial vehicles and passenger cars. In the course of increasing demands on the pollutant poverty increasing return rates are required, for example, to over 30%. Irrespective of measures such as exhaust gas cooling, the recirculated exhaust gas can have very high temperatures, depending on the recirculation rate and the operating state. It is known and customary to provide the inflow of the recirculated exhaust gas into the combustion air in a metal plenum region (intake manifold).

It is the object of the invention to provide a device for exhaust gas recirculation for an internal combustion engine, by means of which a large flow of hot exhaust gas can be introduced into the combustion air in a simple manner.

The object of the invention is achieved for an aforementioned device by the characterizing features of claim 1. By forming the exhaust pipe in a region of its mouth into the channel as at least one pipe section with a plurality of exhaust ports for the exhaust gas along the pipe section, a division of the exhaust gas stream into a plurality of partial streams over a large spatial area is achieved. As a result, excessive local heating, for example, a wall of the channel, avoided and also improves the mixing of exhaust gas and air.

In this case, the exhaust pipe branches in the region of their confluence in a plurality of pipe sections, whereby a particularly uniform distribution of the exhaust gas is achieved.

According to the invention, the outflow openings are distributed according to number and / or size over a length of the pipe section such that a hydraulic outflow cross section per unit length of the pipe section increases in the flow direction of the exhaust gas. As a result, an occurring pressure drop over the length of the pipe section is taken into account, so that the outflowing exhaust gas mass flow can be distributed as required and in particular uniformly over the length of the pipe section.

As a supplemental or alternative advantageous measure flow obstacles are arranged on at least some of the outflow openings, whereby a swirling achieved and / or a preferred outflow direction can be specified. In this way, a harmful heat input, for example, in the walls of the channel can be additionally avoided.

To optimize the distribution of the exhaust gas in the air flow flowing through the channel and thus to equalize the temperature or avoid temperature peaks, it may be provided that the outflow openings at least predominantly in an outflow angle of between 45 ° and 135 °, in particular between 90 ° and 135 °, are aligned with a main flow direction of the air in the channel.

Further advantages and features of a device according to the invention will become apparent from the embodiments described below and from the dependent claims.

Fig. 1

zeigt eine Schnittansicht durch ein erstes Ausführungsbeispiel .

Fig. 2

zeigt eine Draufsicht auf ein Montageglied des Beispiels aus Fig.1.

Fig. 3

zeigt eine seitliche und stirnseitige Draufsicht auf eine Abgasleitung des Beispiels aus Fig. 1.

Fig. 4

zeigt eine Schnittansicht eines zweiten Ausführungsbeispiels .

Fig. 5

zeigt eine Schnittansicht eines dritten Ausführungsbeispiels .

Fig. 6

zeigt eine Draufsicht auf das Beispiel aus Fig. 5.

Fig. 7

zeigt eine Schnittansicht eines vierten Ausführungsbeispiels .

Fig. 7a

zeigt eine Abwandlung des vierten Ausführungsbeispiels.

Fig. 8

zeigt eine Draufsicht auf ein fünftes Ausführungsbeispiel .

Fig. 9

zeigt eine Draufsicht auf ein sechstes Ausführungsbeispiel von oben.

Fig. 10

zeigt das Beispiel aus Fig. 9 mit eingesetzter Abgasleitung.

Fig. 11

zeigt eine Schnittansicht durch ein siebentes Ausführungsbeispiel .

Fig. 12

zeigt eine Schnittansicht durch ein achtes, erfindungsgemäßes Ausführungsbeispiel.

Fig. 13

zeigt eine Schnittansicht durch ein neuntes Ausführungsbeispiel mit erfindungsgemäßen Merkmalen.

Fig. 14

zeigt eine Schnittansicht durch ein zehntes Ausführungsbeispiel.

Fig. 15

zeigt vier Schnittansichten und teilweise Draufsichten in mehreren Ebenen des Ausführungsbeispiels aus Fig. 14.

Fig. 16

zeigt verschiedene Ausströmwinkel eines elften Ausführungsbeispiels.

Hereinafter, several preferred embodiments of the invention will be described and explained in more detail with reference to the accompanying drawings.

Fig. 1

shows a sectional view through a first embodiment.

Fig. 2

shows a plan view of a mounting member of the example Fig.1 ,

Fig. 3

shows a side and frontal plan view of an exhaust pipe of the example Fig. 1 ,

Fig. 4

shows a sectional view of a second embodiment.

Fig. 5

shows a sectional view of a third embodiment.

Fig. 6

shows a plan view of the example Fig. 5 ,

Fig. 7

shows a sectional view of a fourth embodiment.

Fig. 7a

shows a modification of the fourth embodiment.

Fig. 8

shows a plan view of a fifth embodiment.

Fig. 9

shows a plan view of a sixth embodiment from above.

Fig. 10

shows the example Fig. 9 with inserted exhaust pipe.

Fig. 11

shows a sectional view through a seventh embodiment.

Fig. 12

shows a sectional view through an eight, inventive embodiment.

Fig. 13

shows a sectional view through a ninth embodiment with features of the invention.

Fig. 14

shows a sectional view through a tenth embodiment.

Fig. 15

Fig. 4 shows four sectional views and partial plan views in several planes of the embodiment Fig. 14 ,

Fig. 16

shows different discharge angle of an eleventh embodiment.

The exhaust gas recirculation apparatus according to the first embodiment (FIG. Fig. 1 ) comprises a designed as a perforated aluminum plate mounting member 2, which is set over a side opening of a compressed combustion air leading channel 1. The determination of the channel can be made arbitrarily, such as by gluing, positive recording or screwing.

The mounting member has a central opening 2a, in which an exhaust pipe 3 made of a temperature-resistant material, such as stainless steel, is introduced, so that the exhaust gas (dashed arrow) flows into the channel for mixing with the combustion air (solid arrows). The position of the inflow into the channel 1 is upstream of a charge air cooler.

At the exhaust pipe 3, a flange 4 is provided, by means of which the mounting member 2 and the exhaust pipe 3 are sealingly connected together. For this purpose, there is a seal 5 between flange 4 and mounting member 2. The flange 4 is by means of screws (not shown), the corresponding bolt holes 4a, 2b pass through the flange and mounting member, releasably secured.

To cool the mounting member, a coolant channel 6 is provided on it, which rotates the opening 2a. The coolant channel 6 is located on the opposite side of the flange 4 and is formed as a round pipe. The coolant channel 6 consists in the present case of aluminum and is soldered flat on the plate 2. Its (not shown) connection to a coolant circuit can be done by simply attaching hoses on its ends 6a. The coolant circuit may be, for example, the cooling circuit of the internal combustion engine or else a separate or connected low-temperature cooling circuit.

• Im Betrieb des Verbrennungsmotors wird ein einstellbarer Teil des Abgasstroms abgezweigt und -gegebenenfalls nach Kühlung in einem (nicht gezeigten) Abgaskühler durch die Abgasleitung 3 der verdichteten Verbrennungsluft in dem Kanal 1 zugeführt. Dabei kann sich die Abgasleitung auf eine hohe Temperatur von mehreren hundert °C erhitzen. Eine Beschädigung des Material des Kanals 1 wird dadurch ausgeschlossen, dass die Abgasleitung im Bereich ihrer Einmündung Wärme an das Kühlmittel in dem Kühlmittelkanal 6 abführt, so dass das Montageglied 2 zumindest im Bereich seiner Berührung mit dem Kanal 1 jederzeit eine unkritische Temperatur aufweist. Durch die Dichtung 5 wird eine zusätzliche Isolation zwischen Montageglied 2 und Abgasleitung 3 geschaffen.

The invention now works as follows:

• During operation of the internal combustion engine, an adjustable part of the exhaust gas flow is branched off and, if necessary, after cooling in an exhaust gas cooler (not shown), is supplied through the exhaust gas line 3 to the compressed combustion air in the channel 1. In this case, the exhaust pipe can be heated to a high temperature of several hundred ° C. Damage to the material of the channel 1 is precluded by the fact that the exhaust pipe in the region of its junction dissipates heat to the coolant in the coolant channel 6, so that the mounting member 2 at any time at least in the region of its contact with the channel 1 has an uncritical temperature. By the seal 5 additional insulation between the mounting member 2 and exhaust pipe 3 is created.

• Im Unterschied zur Ausführung nach Fig. 1 hat hier das Rohr des Kühlmittelkanals 6 einen rechteckigen Querschnitt, so dass eine besonders große Kontaktfläche zwischen Kühlmittelkanal 6 und Montageglied 2 zur Verfügung steht.

Second embodiment ( Fig. 4 ):

• Unlike the execution after Fig. 1 Here, the tube of the coolant channel 6 has a rectangular cross section, so that a particularly large contact area between the coolant channel 6 and mounting member 2 is available.

Third embodiment (Fig. 5):

In contrast to the first two embodiments, the coolant channel 6 is here formed by a patch on the mounting plate, the mounting member 2 through open sheet metal part 6b, so that the mounting member 2 forms a part of the wall of the coolant channel 6. The molded part 6b is connected in a planar manner to the mounting member 2, wherein, for example, one of the parts may be formed from a solder-plated metal sheet. Fig. 6 shows by way of example, which course the sheet metal part 6b can give the coolant channel 6. At the sheet metal part 6b terminals 6a are also provided for the coolant circuit.

Fourth Embodiment (Figs. 7, 7a):

In contrast to the third embodiment, here coolant channel 6 and flange 4 are arranged from the same side of the mounting member 2. The flange 4 sits with its seal 5 directly on the sheet metal part 6b, so that a particularly good and actively cooled insulation between flange 4 and 2 mounting member is given. In Fig. 7a is shown that the sheet metal part can also be composed of several sections 6b, 6c.

Fifth Embodiment (FIG. 8):

In contrast to the third embodiment (see, for example Fig. 6 ) Here, the coolant channel is shaped so that it includes the fastening screws 2b for the flange. As a result, these thermal bridges are actively cooled.

Sixth Embodiment (FIGS. 9, 10):

In the sixth embodiment, the device according to the invention is constructed in the same unit with an indirect or coolant-flow intercooler 7 with air-flowed and coolant-flow-through flat tubes 9, which are in the immediate vicinity of the Exhaust pipe is located. In this case, a bottom 8 of the intercooler 7 is enlarged or formed so that it comprises an opening 8a for the exhaust pipe 3. In addition, a collector cover 10 is formed accordingly.

It can be provided to combine the header cover 10 or water tank of the intercooler and a cooling channel 6 in a deep-drawn sheet metal part, for example. Depending on the shape of a cooling duct 6 is not necessarily provided in this embodiment, since an active cooling of the exhaust pipe 3 is already given due to the punching through of the collector. In the present drawings Fig. 9, Fig. 10 However, it is evident that a coolant channel 6 is formed with a connection 6a, wherein the connection 6a is at the same time a connection of the intercooler to the coolant circuit.

Seventh Embodiment (Fig. 11):

Fig. 11 shows an example Fig. 9, Fig. 10 Similar embodiment of the invention, in which the exhaust pipe 3 opens directly into a charge air cooler 7. A flange 4 of the exhaust pipe 3 is seated on a collector box 10 sealingly, wherein the collector box 10 rotates a swept by the exhaust pipe 3 and not flowed around by the coolant recess 11. In this example, the header box 10 may be considered as a whole as a coolant passage for the exhaust pipe.

In addition, the protruding into the intercooler 7 exhaust pipe 3 is formed as a pipe section 12 having a plurality of radially directed exhaust ports 13 for the exhaust gas. As a result, the exhaust gas is divided into a plurality of small partial flows, so that local overheating of components of the charge air cooler 7 is avoided. In principle, such a pipe section 12 can also lead, while maintaining these advantages, into a simple channel 1, see, for example, the first exemplary embodiment.

In the present case, the pipe section 12 is closed at the end, being received with its closed end in a seal 14 in an opening of the bottom 8 opposite the inlet-side bottom 8 '. Of course, depending on the construction, the pipe section can also protrude freely into the intercooler 7.

Eighth embodiment (Fig. 12):

In the eighth exemplary embodiment, in contrast to the seventh exemplary embodiment, a branching of the exhaust gas line into a plurality of, in the present case three, tube sections 12 occurs, as a result of which an even more distributed outflow of the exhaust gas is achieved. The branching takes place inside the charge air cooler behind the recess 11 or the inlet-side bottom 8.

Ninth Embodiment (FIG. 13):

This example relates to a further development of an exhaust pipe with 3 with pipe section 12 as in the example Fig. 11 , In the present case, the outflow openings 13 are formed over the course of the pipe section 12 with increasing spatial density (see upper cut edge of the pipe section 12) or with an increasing cross-sectional area at the same distance (see lower cut edge of the pipe section 12). In any case, this achieves the result that a hydraulic outflow cross section per unit length of the pipe section 12 increases in the flow direction, so that the pressure drop of the exhaust gas associated with the outflow is compensated. Overall, this results in a more uniform mass flow of the outflowing exhaust gas over the length of the pipe section 12.

Tenth embodiment (Figures 14, 15):

As a further possibility of influencing the exhaust gas outflow are in the example after Fig. 14 Flow obstacles 15 over at least some the discharge openings 13 are provided. In the present case, the flow obstacles 15 are designed as pushed-on sheet-metal rings which, at the points of overlap with the outflow openings 13, comprise dimensioned and erected tabs. Depending on the position of the pipe section 12, the tabs or flow obstacles 15 are shaped differently and / or placed. Fig. 15 shows for clarity four sections through the four in Fig. 14 shown metal rings together with respective section of a plan view of the tabs.

Eleventh Embodiment (Fig. 16):

In Fig. 16 the flows of charge air (solid lines) and from a pipe section 12 inflowing exhaust gas (dashed lines) are shown, wherein the outflow openings are each arranged at different angles to the plane of symmetry or main flow direction of the charge air.

It will be appreciated that a too compact exhaust plume is formed at too small angles (e.g., 0 °) as well as too large angles (e.g., 180 °). This means a poorer mixing and the risk of local overheating of components of the charge air duct or intercooler.

Preferably, therefore, an angle to the geometric flow direction of the charge air (in the figures in each case horizontally from right to left) is selected for the outflow 13, which is between 45 ° and 135 °, preferably between 90 ° and 135 °.

It is understood that all individual features of the embodiments described above can be meaningfully combined with each other depending on the requirements. In particular, the provision of a pipe section 12 with a plurality of outflow openings 13 with its respective detailed developments with any of the embodiments combined. In a possible embodiment of the invention, it is not necessarily provided that the exhaust pipe 3 is cooled with the pipe section 12 by a coolant. By the pipe section 12 per se, a more uniform distribution of the hot exhaust gas over a larger spatial area can be done, so that a critical heat exposure is avoided, for example, on a channel wall.

Claims (3)

1. A device for exhaust gas recirculation for a combustion engine, comprising
   an exhaust gas line (3) for conducting exhaust gas, and
   a channel (1) for supplying air to the combustion engine,
   wherein the exhaust gas line (3) leads into the channel (1),
   characterised in that the exhaust gas line (3), in a region of the insertion thereof into the channel (1), is formed as at least one tube section (12), wherein a plurality of outflow openings (13) for the exhaust gas is provided along the tube section (12), wherein the outflow openings (13) are distributed along a length of the tube section (12) with respect to the number and/or size thereof such that a hydraulic outflow cross-section per unit of length of the tube section (12) increases in the flow direction of the exhaust gas such that the pressure drop of the exhaust gas in connection with the outflow is compensated, wherein the exhaust gas line (3), in the region of the insertion thereof, branches into a plurality of tube sections (12).
2. The device as claimed in claim 1, characterised in that flow obstacles (15) are disposed on at least a few of the outflow openings (13).
3. The device as claimed in one of the claims 1 or 2, characterised in that the outflow openings (13) are oriented at least predominantly at an outflow angle of between 45° and 135°, in particular between 90° and 135°, with respect to a main flow direction of the air in the channel (1).

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