EP2103893A1 - Heat exchanger for a motor vehicle and method for its production - Google Patents

Abstract

The heat exchanger has an exchanger tube (5) for guiding fluid, and housing (1) surrounding the tube for guiding of another fluid, which passes the tube (5) for heat exchange with the former fluid, where the tube is designed as an extrusion press profile or multiple chambers. The tube with ends is fixed at the base (5a, 5b) in a fluid sealed manner. Ends of the tube are fixed and molded in the base, where the tube consists of aluminum alloy or unalloyed aluminum, and stainless steel. The tube exhibits a structure on an outer side and/or inner side. The base is designed as a pressure casting part on basis of aluminum. An independent claim is also included for a method for manufacturing the heat exchanger.

Description

The invention relates to a heat exchanger for a motor vehicle according to the preamble of claim 1 and a method for producing such a heat exchanger.

In particular, for heat exchangers for cooling recirculated exhaust gas for pollutant reduction of diesel and gasoline engines has already been proposed to provide aluminum extruded profiles as a bundle of exchanger tubes, wherein the exhaust gas is guided in one or more separate chambers of the extruded profiles. To produce such a heat exchanger, the extruded profiles or exchanger tubes must be sealingly connected at their ends to the bottom of the heat exchanger by means of local welding.

It is the object of the invention to provide a heat exchanger for a motor vehicle, which is permanently reliable in a simple and cost-effective production.

This object is achieved for an aforementioned heat exchanger for a motor vehicle according to the invention with the characterizing features of claim 1. By pouring the pipe end into the bottom of the heat exchanger, a particularly dense and reliable connection of the components tube and bottom is achieved together, wherein also by simultaneous pouring a whole bundle of exchanger tubes a particularly easy production is possible. In particular, compared to a complex welding or soldering of exchanger tubes used in perforations of a prefabricated floor offers a cast variant of exchanger tubes many advantages.

A fluid in the sense of the invention means any gaseous or liquid medium. In preferred embodiments, at least one of the fluids is an exhaust gas or compressed charge air or a mixture of exhaust gas and charge air. Within the meaning of the invention, the term heat exchanger also means a complete module, for example an exhaust module and / or intercooler module, into which further components, such as switching valves, are integrated.

In a particularly advantageous embodiment, the tube is formed as an extruded profile. Extruded profiles allow cost-effective even a complex shape. So z. B. a plurality of adjacent chambers may be provided for guiding the first fluid, whereby mechanical stability and heat transfer are improved for a given size.

To reduce the weight and the cost is provided in a preferred development that the tube consists of an aluminum alloy or unalloyed aluminum.

In another embodiment, the tube is a welded or drawn tube of stainless steel. This can be in particular both ferritic and austenitic stainless steel. Tubes of this type can be shaped differently, e.g. round or rectangular, as well as to increase the cooling capacity and reduce pollution have a complex structuring. This structuring can be executed as winglets or dimples. However, it is also possible to use other structured tubes, such as twisted tubes or twisted tubes, which are customary in heat exchanger construction.

Generally advantageous and in particular in the form of an extruded profile, the tube can be expediently designed as a multi-chamber tube. Alternatively or additionally, the tube may have a structuring on its outside and again alternatively or additionally on its inside. The structuring is particularly advantageously designed to improve the heat transfer at a given size at least partially as extending in the longitudinal direction grooves or ribs.

In a preferred embodiment of the invention, one of the two fluids is gaseous and the other of the two fluids is liquid. In this case, in particular, the gaseous fluid can at least partially consist of exhaust gas of an internal combustion engine of the motor vehicle. Alternatively or additionally, it may also consist at least partially of charge air of an internal combustion engine of the motor vehicle. The gaseous fluid can have a very high temperature, which is why, in a particularly expedient embodiment of the invention, there is no contact between the gaseous fluid and sealing means, at least in the area of the heat exchanger.

In a first advantageous embodiment, the gaseous fluid is guided inside the tube. As a result, contact of gaseous fluid and the housing material surrounding the tubes of the heat exchanger is avoided, which is particularly advantageous for critical properties of the gaseous fluid such as temperature and corrosivity. In an alternative embodiment depending on the design, however, provision may also be made for the gaseous fluid to be conducted outside the tube.

In a first advantageous embodiment, the heat exchanger is designed as an I-flow heat exchanger, wherein the tube is cast with a second end in a further bottom of the heat exchanger. In an alternative embodiment, the heat exchanger is designed as a U-flow heat exchanger. In a possible detail design, the tube is cast with the first end and a second end in the ground. In an expedient embodiment, at least the bottom is formed as a casting or die-cast part, in particular based on aluminum. By means of die casting, for example, complex shapes can be produced inexpensively in large quantities.

In a particularly preferred detailed design, the tube undergoes at least predominantly no heating of more than 550 ° C, in particular not more than 500 ° C in the course of pouring into the soil. Such a targeted limitation of the heating can z. B. serve to prevent an unfavorable change in the crystal structure of the tubes during pouring into the soil. It has thus been found, for example, that aluminum extruded profiles made from standard Al-alloy extrusions of certain Al alloys are particularly resistant to corrosion by hot exhaust gases and acidic exhaust gas condensates and are therefore surprisingly suitable for the construction of exhaust gas heat exchangers of motor vehicles. These advantageous properties are due to the chemical composition in connection with the fine crystalline structure of the aluminum extruded profiles, which is why unfavorable temperature treatments of the finished extruded profiles in the course of the production of the heat exchanger are undesirable.

In the aforementioned sense, it can preferably be provided that the pipe is cooled in the course of pouring into the ground by means of a casting core and / or a casting tool. A casting core can z. B. in the form of a sheath of an adjusted tube bundle by sand or similar substances, so that over the period of pouring the pipe ends sufficient cooling of the unenclosed part of the tubes or extruded profiles, is ensured. It can also be an active cooling by means of a suitable design of the casting tool, z. Example, by the pipes are flowed through during the process of pouring into the ground of a coolant supplied via the casting tool. In particular, the fluid-carrying surfaces of the tubes could be protected in this way from being heated during the casting over its entire length, so that properties due to the crystal structure, such as a good corrosion resistance to exhaust gases, are maintained.

The invention also relates to an intake module for an internal combustion engine of a motor vehicle, comprising a heat exchanger according to one of claims 1 to 17. More and more are found in modern intake modules Components and components integrated to optimize the operation of an internal combustion engine. Among other things, these may be cooling components for cooling the supplied gas or gas mixture. An inventive heat exchanger can be at least partially poured into the intake module to a cost-effective and reliable manner an integrated unit of z. B. intake module and exhaust gas cooler and / or intercooler to get.

The invention also relates to a method for producing a heat exchanger according to any one of claims 1 to 17 according to the features of claim 20. The use of extruded profiles allows cost-effective mass production of particularly effective heat exchangers, wherein extruded sections, inter alia, for cooling of hot corrosive exhaust gas and / or are suitable for cooling the charged charge air or mixtures of exhaust gas and charge air of an internal combustion engine.

Fig. 1

zeigt eine schematische Darstellung eines ersten Ausführungsbeispiels eines Wärmetauschers mit einem separat dargestellten Deckelteil.

Fig. 2

zeigt eine schematische Draufsicht auf die Ausführung aus Fig. 1 von der Seite.

Fig. 3

zeigt eine Schnittansicht durch ein Rohrbündel der Ausführung nach Fig. 1 gemäß einer ersten Abwandlung.

Fig. 4

zeigt eine Schnittansicht durch das Rohrbündel aus Fig. 1 gemäß einer zweiten Abwandlung.

Fig. 5

zeigt eine Draufsicht auf eine weitere Ausführungsform eines erfindungsgemäßen Wärmetauschers.

Fig. 6

zeigt ein in ein Gehäuse integriertes Tauscherrohr eines weiteren Ausführungsbeispiels der Erfindung.

Fig. 7

zeigt eine schematische Darstellung eines Verbrennungsmotors mit einem erfindungsgemäßen Ansaugmodul.

Fig. 8

zeigt eine Abwandlung des Ansaugmoduls aus Fig. 7.

Fig. 9

zeigt eine weitere Abwandlung eines erfindungsgemäßen Ansaugmoduls.

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

Fig. 1

shows a schematic representation of a first embodiment of a heat exchanger with a separately shown cover part.

Fig. 2

shows a schematic plan view of the embodiment Fig. 1 of the page.

Fig. 3

shows a sectional view through a tube bundle of the embodiment according to Fig. 1 according to a first modification.

Fig. 4

shows a sectional view through the tube bundle Fig. 1 according to a second modification.

Fig. 5

shows a plan view of another embodiment of a heat exchanger according to the invention.

Fig. 6

shows an integrated in a housing exchanger tube of another embodiment of the invention.

Fig. 7

shows a schematic representation of an internal combustion engine with an intake module according to the invention.

Fig. 8

shows a modification of the intake module Fig. 7 ,

Fig. 9

shows a further modification of an intake module according to the invention.

The first embodiment of a heat exchanger according to the invention according to Fig. 1 comprises a housing 1, which is produced by die casting from an aluminum alloy. In Fig. 1 the housing 1 is shown in an open form next to a cover part 2, wherein the cover part 2 is shown in a schematic sectional view for the representation of arranged in the cover part 2 coolant channels. The housing 1 has a feed 3 and a discharge 4 for a gas flow of an internal combustion engine. The device or the heat exchanger according to Fig. 1 serves the cooling of a recirculated exhaust gas flow to reduce pollutants of the internal combustion engine of a motor vehicle.

The housing 1 has a first, inner wall portion 1 a and an outer, the first wall portion 1 a spaced circumferential wall portion 1 b. The inlets and outlets 3, 4 designed as connecting stubs are arranged at openings of the outer wall 1b and open into an inlet region 6 enclosed on three sides by the first, inner wall 1a. A bundle of exchanger tubes 5 adjoins this inlet region 6 are each formed as aluminum extruded profiles. The exchanger tubes 5 are in each case straight tube sections, which are accommodated with each of the two ends in each case in a first, inlet-side and a wall of the inlet region 6 forming bottom 5a and a second, exit-side bottom 5b. The inclusion of the ends of the exchanger tubes 5 takes place during the production of the heat exchanger by pouring the prefabricated extruded profiles 5 in the housing 1. The bottoms 5a, 5b are formed as integral parts of the inner housing wall 1a integral.

The extruded profiles 5, as in the modification according to Fig. 3 shown to have a simple round cross section. Alternatively, you can also, as in the modification according to Fig. 4 shown, have a rectangular cross section, wherein in particular within the cross section a plurality of separate chambers 5c may be separated.

The exchanger tubes 5 can be flowed around by a liquid coolant, which is supplied and removed by means of connections 15. Between the inlet and outlet 3, 4 of the exhaust gas or first fluid of the heat exchanger, which are arranged side by side on the same side of the housing 1, the inlet region 6 is provided for the gas flow within the first wall 1a. On the other side of the bundle of exchanger tubes 5 with regard to the gas flow, a deflection region 7 is provided between the inner wall 1a and the outlet-side bottom 5b. In addition, in the entry region 6, a movable actuator 9 in the form of an adjusting flap is provided on suitably designed guide structures 8. By means of this valve 9, the exhaust stream adjustable either directly from the feed 3 to the discharge 4 are passed or passing through the exchanger tubes 5. Thus, by the actuator 9, a bypass operation selectable, which may be desired depending on the operating condition of the engine.

Between the inner wall portion 1 a and the outer wall portion 1 b remains a narrow gap 1 c for the flow of coolant. As a result, in particular the inner wall section 1a is cooled, which is required above all in the inlet region 6 due to the high temperatures of the exhaust gas flow, since the housing 1 consists of an aluminum alloy.

The housing 1 is formed at least with the inner wall portion 1 a and the outer wall portion 1 b as integrally molded die-cast aluminum alloy.

A lower housing wall 10 of the housing 1 may also be integrally formed with the wall sections 1a, 1b in the die-casting process. In the plan view according to Fig. 1 Then, a one-sided demolding of the casting would be given, wherein both the gas-conducting region and the coolant-carrying region would be formed by the same casting mold side.

The cover part 2, which forms an upper cover of the housing 1, is made up of a total of three plate elements 2a, 2b, 2c (see FIG Fig. 2 ) composed of aluminum and are soldered flat to each other. Each of the plate elements 2a, 2b, 2c has suitable openings, which serve to distribute the liquid coolant. The upper plate member 2a has an opening for connecting a supply 11 for the coolant. The middle plate element 2c, which in the plan view in Fig. 1 is shown has channels 12, 13, 14 in which the coolant flows in the plane of the cover part 2. The lower plate member 2c has openings 15, by means of which a connection of the channels 12, 13, 14 with the area around the exchanger tubes 5 and with the other coolant-carrying spaces 1c of the housing 1 between the walls 1a, 1b are produced. The lid member may be formed in a simple embodiment, if it does not come into contact with the hot exhaust gas stream, made of plastic.

As in particular the sectional view according to Fig. 2 shows, the entire coolant flows through the feed 11 and the opening in the upper plate member 2a in the channel 12 of the central plate member 2b and by a congruent opening of the lower plate member 2c in the area around the exchanger tubes 5. After circulation around the exchanger tubes 5 occurs the coolant through a further opening of the lower plate member 2 c in the channel 13 of the central plate member 2 a, from which it is passed through the channels 14 in a coolant-carrying shaft 1 d of the housing 1. This shaft 1 d is connected to a nozzle 16 for the discharge of the coolant from the housing 1. The shaft 1d is located in the inlet region 6 of the gas flow and is completed on one side of the outer wall 1 b in the immediate vicinity of the feed 3 and discharge 4 of the gas stream. In this way, this temperature-critical region of the wall 1 b is cooled.

The partial flow of the channel 12 of the central plate element 2b is passed through an opening 15 of the lower plate member 2c in a circumferential portion 1c surrounding the majority of the housing 1, so that the largest possible part of the contacting with the gas flow wall portion 1a is cooled by the coolant , By means of suitable perforations in the lower plate element 2 c and the channels 14 of the middle plate element 2 b, this partial flow is also supplied to the part 1 d, so that the entire coolant leaves the housing 1 via the discharge connection 16.

At the in Fig. 5 illustrated modification of the first embodiment described above, the exchanger tubes 5 are each bent in a U-shape and open with their beginning and their end in each case in the same bottom 5a, in which they are firmly cast during the production of the heat exchanger. As in the first embodiment according to Fig. 1 Thus, a U-flow heat exchanger is formed, but only a single bottom 5a is required and the second bottom 5b and the reverse portion 7 omitted. This makes it possible to fill a larger area within the wall 1a from the gas-carrying and coolant-exchanged exchanger tubes 5.

Fig. 6 shows a spatial representation of a portion of another embodiment of a heat exchanger according to the invention, in which an inner portion 102 of an extruded profile 101 is formed for the guidance of exhaust gas and elongated, rib-like structures 103 to increase the heat transfer. This inner tube portion of the extruded profile 101 is connected via web-like structures 104 with a housing tube 105 enclosing housing, wherein longitudinal chambers 106 remain between outer tube 105 and inner region 102, in which a liquid coolant for dissipating the heat of the exhaust gas is guided.

Such an integrally one-piece extruded profile with channels for guiding exhaust gas as well as for the guidance of liquid coolant requires a connection to the two fluids. Such a connection can be applied to the extruded profile in the die casting process, so that the extruded profile is cast in a housing in the sense of the invention.

Fig. 7 shows a first embodiment of an intake module according to the invention with a heat exchanger according to the invention integrated therein. Shown is a schematic view of an internal combustion engine 201 to which an intake module 202 for supplying air or combustion mixture is flanged on the inlet side. The intake module 202 is largely formed as an aluminum die-cast part. It has a throttle valve 203, which is arranged in a feed channel 204, in which a charge air cooler 205 is located. The intercooler 205 has a plurality of exchanger tubes 206 received between an entrance side floor 207 and an exit side floor 208. This recording can, for the purposes of the invention by pouring z. B. sections of extruded profiles or other pipe sections 206 in the intake 202 in the course of its original formation.

According to one embodiment, not shown, the intercooler is constructed so that the pipes are traversed by the liquid coolant and flows around on the outside of the compressed charge air or a mixture of compressed charge air and exhaust gas. For better heat transfer, the tubes then preferably have a structured outer surface in the form of ribs, webs, dimples, winglets or the like. Also in this embodiment, the heat exchanger may be formed as described above as an I-flow or U-flow heat exchanger. In a particular embodiment, this outer structure of the tubes is plugged in the form of corrugated ribs.

The intercooler 205 has ports 209 for supplying and discharging a liquid refrigerant from which the exchanger tubes 206 are flowed around to remove the heat of the compressed charge air.

In addition, a module comprising a heat exchanger according to the invention for supplying recirculated and selectably cooled exhaust gas is provided on the intake module 202. For this purpose, the exhaust gas is branched off from an exhaust pipe 210 and fed to a housing region 211. In the area of the inlet of the exhaust gas into the housing area 211, an actuator 212 is provided in the manner of a linear slide, by means of which the recirculated exhaust gas, depending on the operating state, cooled either without cooling via a bypass line 213 or through a heat exchanger 214 according to the invention to the further intake module 202 and the internal combustion engine 201 can be supplied.

The heat exchanger 214 according to the invention comprises a bundle of exchanger tubes 215 in the form of extruded profiles, which are cast in a first bottom 216 and a second bottom 217. The floors 216 and 217 are simply formed as wall sections of the housing portion 211 of the intake module 202.

If appropriate, a cover 218 is placed using sealing means in such a way that a circulation of the exchanger tubes 215 with the coolant can take place by means of inlets and outlets 219 for liquid coolant provided in particular in the cover. The lid may be made of metal, e.g. Die-cast aluminum, or be formed in a simple embodiment of plastic.

Fig. 8 shows a modification of the embodiment according to Fig. 7 , Wherein the exhaust gas flowed through exchanger tubes 215 are not straight, but are formed as bent portions. In the present schematically sketched example, the tubes 215 each form 90 ° -Kreissektoren. In principle, however, depending on the design of the housing and the space available, they can be shaped and have a plurality of bends or complex courses.

In the modification of a suction according to the invention according to Fig. 9 be in contrast to the embodiments after Fig. 7 and Fig. 8 formed as extruded exchanger tubes 215 does not flow through the exhaust gas, but by the liquid coolant. For this purpose, the tubes U-shaped bent in the present example 215 are cast with their ends in an outer wall 220 of the intake module, so that they open with both ends in the outer space. To supply the tubes with coolant from the outside lid 221 are cast or placed, in turn, through the lid 221 connections 222 can be formed for the supply and discharge of coolant.

In this embodiment, the coolant-carrying curved tubes 215 are in their course within the exhaust gas-carrying housing portion 211, so that they are flowed around with a corresponding position of the slider 212 of exhaust gas, which emits its heat corresponding to the flowing in the tubes coolant.

It is understood that the individual special features of the described embodiments can be usefully combined depending on the requirements.

Claims (15)

A heat exchanger for a motor vehicle, comprising at least one tube (5) for guiding a first fluid and a housing (1) surrounding the tube (5) for guiding a second fluid, the second fluid containing the tubes (5) for heat exchange with the first fluid flows around, wherein the tube (5) with at least one first end fluid-tight to a bottom (5a, 5b) is fixed, characterized in that the at the bottom (5a, 5b) fixed end of the tube (5) in the bottom (5a , 5b) is poured. Heat exchanger according to claim 1, characterized in that the tube (5) is designed as an extruded profile. Heat exchanger according to claim 1 or 2, characterized in that the tube (5) consists of an aluminum alloy or unalloyed aluminum. Heat exchanger according to one of the preceding claims , characterized in that the tube (5) as a welded or drawn tube, in particular made of stainless steel is formed. Heat exchanger according to one of the preceding claims, characterized in that the tube (5) as a multi-chamber tube (5c) is formed. Heat exchanger according to one of the preceding claims, characterized in that the tube (5) has a structuring on its outside and / or inside. Heat exchanger according to claim 6, characterized in that the structuring is at least partially formed as a longitudinally extending grooves. Heat exchanger according to claim 6 or 7, characterized in that the structuring is designed as introduced winglets and / or dimples and / or as a twist of the tube (5). Heat exchanger according to one of the preceding claims, characterized in that one of the two fluids is gaseous and the other of the two fluids is liquid. Heat exchanger according to claim 9, characterized in that the gaseous fluid at least partially consists of exhaust gas of an internal combustion engine of the motor vehicle. Heat exchanger according to claim 9 or 10, characterized in that the gaseous fluid consists at least partially of charge air of an internal combustion engine (201) of the motor vehicle. Heat exchanger according to one of claims 9 to 11, characterized in that the gaseous fluid, at least in the region of the heat exchanger has no contact with sealants. An intake module for an internal combustion engine of a motor vehicle, comprising a heat exchanger according to one of claims 1 to 12. Intake module according to claim 13, characterized in that the heat exchanger is at least partially cast into the intake module (202). Process for producing a heat exchanger according to one of Claims 1 to 12, comprising the steps: Producing the tube (5) as an extruded profile or as a welded tube or as a drawn tube; Integrating the tube (5) by pouring into a bottom (5a, 5b) of the heat exchanger, in particular by means of aluminum die casting.

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