EP3232149B1 - Heat exchanger - Google Patents

Description

The present invention relates to a heat exchanger with a housing and with a heat exchanger block arranged therein according to the preamble of claim 1. The invention also relates to a method for producing such a heat exchanger.

From the DE 10 2005 012 761 A1 a generic heat exchanger with a housing and a heat exchanger block arranged therein is known, which has a tube bundle with a plurality of flat tubes, which are longitudinally held in complementary trained passages in tube sheets.

From the DE 10 2005 032 812 A1 a heat exchanger with a soldered, consisting of flat tubes and ribs block is known, wherein the flat tubes are flowed through by a first medium and communicate with at least one collecting tank and the ribs are overflowed by a second medium. The ribs themselves are substantially flat and arranged parallel to each other and moreover have openings with contact surfaces, wherein the flat tubes are received in the openings and soldered in the region of the contact surfaces. As a result, in particular, the production costs for such a heat exchanger can be reduced.

From the DE 102 59 026 A1 For example, a heat exchanger with a heat exchanger network consisting of tubes and fins is known, as well as with at least one collection box formed from the sheet metal blank, which has a bottom section with openings into which the tubes open. This bottom portion has on the one hand a bottom longitudinal edge with recess and on the other hand passes into a curved wall section, which in a longitudinal wall edge with tabs ends. The wall longitudinal edge is returned substantially perpendicular to the bottom longitudinal edge and inserted with the tabs in the recesses. As a result, a simple manufacturability of the heat exchanger is to be made possible.

Due to a steadily tightening emissions legislation, increasingly engine-internal measures for emission reduction, in particular for the reduction of nitrogen oxide emissions (NO _X ) must be taken. Here, the thermal management is becoming increasingly important in order to direct the heat flow in the internal combustion engine so and to use so that the highest possible fuel efficiency can be achieved with minimal emissions.

For example, a turbo-charged internal combustion engine, by which weight, space and fuel consumption advantages can be achieved. During turbocharging, the fresh air is brought to a higher pressure and temperature level with the help of a turbo-compressor. Before combustion in the cylinder, the possibly compressed fresh air is mixed with a certain amount of recirculated exhaust gas, thereby reducing the oxygen content and the temperature in the combustion chamber, whereby lower NO _x emissions can be achieved. Another way to reduce the NO _x emissions is to cool both the fresh air after compression, as well as the recirculated exhaust gas by means of a heat exchanger. In addition, the heat taken from the exhaust gas or the fresh air can be used for the faster warming up of a vehicle cabin and / or a faster warming up of the internal combustion engine or a transmission after the cold start, whereby consumption and emission advantages can likewise be achieved.

The heat exchangers used for cooling, in particular in the area of a charge air cooling, are standard in the so-called Rohrbündelbauweise executed. In this case, the tube bundles consist of stacked, gas-conducting flat tubes with internal corrugated fins and lying between the tubes coolant side turbulence inserts, the tube bundles complete by default with one tube to the outside. In this case, the coolant channels located between the tubes are sealed watertight on the outside via two soldered to the flat tubes covers and the front side soldered to the flat tubes tubesheets. The housing is completed by top and bottom soldered side panels, which do not have to fulfill any tightness function.

A disadvantage of such heat exchangers, however, is that in particular the outer flat tubes of the tube bundle are cooled only unevenly, since they are flowing around only on one side of coolant. This leads to thermal stresses, which result in a lower thermo change fatigue strength. However, this thermal fatigue strength determines significantly the suitability of a heat exchanger for the above applications. Due to the anticipated further increase in boost pressures and exhaust gas recirculation rates in the future, the improvement of the thermal shock fatigue resistance is becoming increasingly important. A disadvantage of the known from the prior art heat exchangers beyond that these are relatively expensive to produce, especially using expensive and unwieldy soldering / welding frame.

The present invention therefore deals with the problem of providing a heat exchanger of the generic type an improved or at least one alternative embodiment, which is characterized in particular by a simplified production.

This problem is solved according to the invention by the subject matter of independent claim 1. Advantageous embodiments are the subject of the dependent claims.

The present invention is based on the general idea to provide specific integral with these mechanical fixing elements on individual components of a heat exchanger, which allow a simple mechanical prefixing of the heat exchanger, so that this in a subsequent welding / soldering process no longer expensive and complicated to handle Soldering / welding frame must be kept. The heat exchanger according to the invention has in a known manner a housing and a heat exchanger block arranged therein, which comprises a tube bundle with a plurality of flat tubes, which are held in the longitudinal end of complementary trained passages in tube sheets. According to the invention, this housing now has two U-shaped side parts and two covers, wherein an axially projecting first nose is arranged on each side part in each case in the region of a corner, ie a total of four first lugs each side part, and wherein each cover in each case Corner is arranged in the axial direction projecting second nose, so a total of four second lugs per cover. On an inner side of each tube plate, a rectangular and circumferential first groove is arranged, in which the covers and the side parts are each received on the front side. Each side part and each cover is thus received with a first end face in a first groove of a first tube sheet and the opposite edge at the end face in the opposite first groove of the second tube sheet. In addition, according to the invention, in each corner region of the first groove, in each case one passage opening is arranged, through each of which a first and a second lug are guided, these two lugs being bent and thereby mechanically fixing the respective side part and the respective cover to the associated tube plate. Through each tube bottom reach through the four Through openings thus in each case four first lugs and four second lugs, which allows a mechanical prefixing of the housing and thus a mechanical prefixing of the heat exchanger with the heat exchanger block arranged in the housing, so that this then spent in this mechanically prefixed state in a soldering oven and soldered there or . A subsequent welding process can be supplied without having to be laboriously and cumbersome to be installed in an associated soldering frame or welding frame before. With the mechanical fixing elements according to the invention (lugs and passage openings), the production of the heat exchanger can thus be significantly simplified and thus also produced significantly more cost-effectively.

In an advantageous development of the solution according to the invention, turbulence inserts are arranged between the flat tubes. By means of such turbulence inserts a turbulent flow between the individual flat tubes is achieved and thus achieved an improved heat transfer. Additionally or alternatively, a turbulence insert can also be arranged between each side part and the respectively adjacent flat tube. This is particularly important for increasing the thermal shock fatigue strength of great importance, since in this case the respective outer flat tube is not only washed from one side with coolant, but from two sides. For this reason, the respective side part is arranged at a distance from the adjacent flat tube, so that there is no direct heat-transmitting contact between the outer flat tube and the side part. Of course, additionally or alternatively, corresponding turbulence inserts / corrugated ribs can also be arranged inside the flat tubes, as a result of which an increased heat transfer can also be achieved here.

At least one insertion bevel is expediently arranged on at least one nose. Such chamfers facilitate the assembly of the Housing, that is, the heat exchanger by the insertion of the respective nose is simplified into the associated passage opening.

In an advantageous development of the solution according to the invention, the noses received in each case in a passage opening are bent away from one another. In this way, a reliable fixation of a cover and an adjacent side part can be achieved on a tube sheet.

In a further advantageous embodiment of the solution according to the invention each have a U-leg of the U-shaped side part an angle of attack α of less than 90 ° with respect to a web arranged therebetween. As a result, a defined Lotspalt is generated between the respective U-leg of the side part and the adjoining cover, which generates a particularly dense and reliable soldering.

In a further advantageous embodiment of the solution according to the invention, a peripheral, circumferential second groove is arranged on each outer side of each tube bottom following the edge, in which an edge of a diffuser or a deflecting tank is received. Through this positive recording, a tight connection of the respective tube plate with the diffuser or the Umlenktank can be achieved together with a soldering. In the same way, of course, the covers or the side parts are preferably received positively in the first groove of the respective tube sheet.

The present invention is further based on the idea to provide a simple method for producing the heat exchanger described above, in which initially side parts and covers are so assembled with two tube sheets to form a housing that a respective end face or a respective edge of two side parts and two Covers engage in a circumferential first groove of a first tube plate and that a respective opposite end face or a respective opposite edge of two side parts and two covers engage in a circumferential first groove of an opposite second tube plate. In this state, in each case a corner-side passage opening of the respective tube sheet each engage a first nose of a side part and a second nose of a cover. Then the noses are bent over and the side parts, the covers and the tubesheets are mechanically fixed to each other. Already before flat tubes are usually positioned in the respective passages of the two opposite tube sheets and possibly still arranged turbulence inserts between the individual flat tubes or between each outer flat tube and an associated side part. Such a mechanically prefixed heat exchanger can now be spent without the use of a consuming hand-to-handle and above all expensive soldering frame in a brazing furnace and there soldered at least the heat exchanger block. Of course, in this mechanically prefixed manner, the heat exchanger can also be supplied to further sealing processes, such as, for example, a subsequent welding process, wherein reliable pre-fixing and reliable welding, in particular without distortion, can be achieved.

Other important features and advantages of the invention will become apparent from the dependent claims, from the drawings and from the associated figure description with reference to the drawings.

It is understood that the features mentioned above and those yet to be explained below can be used not only in the particular combination given, but also in other combinations or in isolation, without departing from the scope of the present invention.

Preferred embodiments of the invention are illustrated in the drawings and will be described in more detail in the following description, wherein like reference numerals refer to the same or similar or functionally identical components.

Fig. 1

einen erfindungsgemäßen Wärmeübertrager in einer Explosionsdarstellung,

Fig. 2

eine Schnittdarstellung durch einen Eckbereich zwischen einem Seitenteil und einer Abdeckung,

Fig. 3

eine Draufsicht auf zweite Nasen einer Abdeckung,

Fig. 4

eine Schnittdarstellung durch einen Rohrboden im Bereich einer Durchgangsöffnung mit durchgeschobener erster und zweiter Nase,

Fig. 5

eine Darstellung wie in Fig. 4, jedoch bei umgebogener erster und zweiter Nase.

Show, in each case schematically,

Fig. 1

a heat exchanger according to the invention in an exploded view,

Fig. 2

a sectional view through a corner region between a side part and a cover,

Fig. 3

a plan view of second lugs of a cover,

Fig. 4

a sectional view through a tube plate in the region of a through hole with pushed through the first and second nose,

Fig. 5

a representation like in Fig. 4 , but with bent first and second nose.

According to the Fig. 1 , a heat exchanger 1 according to the invention has a housing 2 with a heat exchanger block 3 arranged therein. The heat exchanger block 3 in this case has a tube bundle with a plurality of flat tubes 4, the longitudinal end side in complementary thereto trained passages 5 a tube plate 6, 7 are held. According to the invention, the housing 2 now has two U-shaped side parts 8, 9 and two covers 10, 11. At each side part 8, 9 each projecting in the axial direction 13 a first nose 12 is arranged in each case in the region of a corner, while at each cover 10, 11 each in the region of a corner projecting in the axial direction 13 second nose 14 is arranged. In addition, on an inner side of each tube plate 6, 7 a the peripheral edge of the tube bottom rectangular, circumferential first groove 15 is arranged, in which the covers 10, 11 and the side parts 8, 9 are each received with a front edge. In addition, in each corner region of the first groove 15 there is in each case a passage opening 16 (cf. 4 and 5 ), through which in each case a first and a second lug 12, 14 is guided, wherein the lugs 12, 14 are bent and thereby fix the respective side part 8, 9 and the respective cover 10, 11 mechanically on the tube bottom 6, 7.

With the housing 2 according to the invention, which essentially consists of the two side parts 8, 9 and the two covers 10, 11, the heat exchanger 1 can be mechanically prefixed with regard to its housing 2 and with respect to the heat exchanger block 3 arranged therein, so that it is mechanically fixed in this case Prefixed state, a subsequent manufacturing step, for example. A welding or soldering, can be supplied without the heat exchanger 1 for this would first have to be clamped in an expensive welding frame or soldering frame.

In order to be able to increase the heat transfer, so-called turbulence inserts 17 are preferably arranged between the flat tubes 4, whereby such turbulence inserts 17 can likewise be arranged within a respective flat tube 4. It is particularly advantageous beyond that, if between each side part 8, 9 and the next adjacent flat tubes 4 such a turbulence insert 17 is arranged, since in this case, the outer flat tube 4 is surrounded on both sides by coolant and thereby exposed to a lower temperature load, whereby the Thermo change fatigue strength can be increased.

Looking closer to the lugs 12, 14, in particular, for example, the two lugs 14 on the cover 10, 11, it can be seen that these are preferably an insertion bevel 18 (see. Fig. 3 ), which facilitate insertion of the respective lug 12, 14 into the associated passage opening 16 on the tubesheet 6, 7. Usually, the two are in each case in a through opening 16 received in lugs 12, 14 bent away from each other, as example. According to the Fig. 5 is shown, and thereby fix the associated cover 10, 11 and the associated side part 8, 9 on each associated tube sheet 6, 7th

Looking at the Fig. 2 , it can be seen that in each case a U-leg 19 of the respective side part 8, 9 has an angle of attack of less than 90 ° to a U-leg 19 connecting web 27, whereby between the U-leg 19 and the associated Cover 10, 11 results in a defined Lotspalt 20, which allows reliable soldering. An inner side 21 of the respective side part 8, 9 is preferably solder-plated, whereby a connection of the adjacently arranged turbulence insert 17 is possible.

Looking again at the Fig. 1 , it can be seen that on each outer side of each tube sheet 6, 7, a rectangular and circumferential second groove 22 is arranged, in which an edge of a diffuser 23 or a Umlenktanks 24 received, in particular positively recorded and, for example, is soldered tightly. Likewise positively received are, for example, the respective edge, that is, the front side of the covers 10, 11 and the side parts 8, 9 in the associated first groove 15 of the respectively associated tube sheet 6, 7th

At the according to the Fig. 1 In addition, a coolant inlet 25 and a coolant outlet 26 are arranged. According to the Fig. 1 In this case, the coolant inlet 25 and the coolant outlet 26 are designated in the area of their respective sockets.

The heat exchanger 1 according to the invention is produced as follows: First, the side parts 8, 9 and the covers 10, 11 are respectively fitted together with the two tube sheets 6, 7 to a housing 2, that a respective end face, that is, a respective edge, two Side parts 8, 9 and two covers 10, 11 engage in a circumferential first groove 15 of the first tube sheet 6 and the respective opposite end face or an opposite edge of two side parts 8, 9 and two covers 10, 11 in a circumferential first groove 15 of an opposite engage second tube bottom 7. The mating is carried out such that in each case a corner-side passage opening 16 of the tube sheet 6, 7 each engage a first lug 12 of a side part 8, 9 and a second lug 14 of a cover 10, 11. Subsequently, the lugs 12, 14 are bent and so the side parts 8, 9 and the covers 10, 11 and the tube sheets 6, 7 fixed mechanically to each other. Within the thus mechanically fixed housing 2, of course, the flat tubes 4 and possibly turbulence inserts 17 have previously been arranged. The thus mechanically prefixed housing 2 with the therein heat exchanger block 3 can now be spent in a further manufacturing step in a brazing furnace and soldered there or in a welding station in which it is welded. Due to the possibility of mechanical prefixing can be dispensed with in particular expensive and cumbersome to handle solder frames or welding frame.

Claims (10)

1. Heat exchanger (1) with a housing (2) and a heat exchanger block (3) arranged within it, which comprises a bundle of tubes with several flat tubes (4), which are held at the long end in eyelets (5) in tube sheets (6, 7) formed complementary to this,
   characterised in that

   - the housing (2) has two U-shaped side pieces (8, 9) and two covers (10, 11),

   - a first lug (12) protruding in an axial direction (13) is located on each side piece (8, 9) near a corner,

   - a second lug (14) protruding in an axial direction (13) is located on every cover (10, 11) near a corner,

   - a circumferential first groove (15) is located on an inner side of each tube sheet (6, 7), in which the covers (10, 11) and the side pieces (8, 9) are housed with an edge on the front side,

   - respectively an opening (16) is located in every corner area of the first groove (15) through which respectively a first and a second lug (12, 14) is guided, whereby the lugs (12, 14) are bend and thus mechanically fix the relevant side piece (8, 9) and the relevant cover (10, 11) to the associated tube sheet (6, 7).
2. Heat exchanger according to claim 1,
   characterised in that
   turbulence inserts (17) are located between the flat tubes (4).
3. Heat exchanger according to claim 1 or 2,
   characterised in that
   a turbulence insert (17) is located between each side piece (8, 9) and the adjacent flat tube (4).
4. Heat exchange according to one of the preceding claims,
   characterised in that
   there is at least one lead-in chamfer (18) located on at least one lug (12, 14).
5. Heat exchanger according to one of the preceding claims
   characterised in that
   the lugs (12, 14) each housed in an opening (16) are bent away from each other.
6. Heat exchanger according to one of the preceding claims
   characterised in that
   one U arm (19) of the U-shaped side piece (8, 9) has an angle α <90° to a bridge (27) connecting the U arm (19).
7. Heat exchanger according to one of the preceding claims,
   characterised in that
   a circumferential second groove (22) is located on each outer side of each tube sheet (6, 7), in which an edge of a diffusor (23) or deflection tank (24) is located.
8. Heat exchanger according to one of the preceding claims
   characterised in that
   the side pieces (8, 9) and the covers (10, 11) are soldered in the first groove (15).
9. Heat exchanger according to one of the preceding claims,
   characterised in that
   a coolant inlet (25) and a coolant outlet (26) are located on one of the two covers (10, 11).
10. Method of manufacturing a heat exchanger (1) according to one of the claims 1 to 9, in which

    - side pieces (8, 9) and covers (10, 11) are respectively plugged together with two tube sheets (6, 7) to a housing (2) so that a relevant edge of the two side pieces (8, 9) and two covers (10, 11) engage in a circumferential first groove (15) of a first tube sheet (6) and that a relevant opposite edge of two side pieces (8, 9) and two covers (10, 11) engage in a circumferential first groove (15) of an opposite second tube sheet (17),

    - in which an opening (16) of the first groove (15) on the corner side engage respectively in a first lug (12) of a side piece (8, 9) and a second lug (14) of a cover (10, 11),

    - the lugs (12, 14) are bent and thus the side pieces (8, 9), the covers (10, 11) and the tube sheets (6, 7) are mechanically fixed to each other,

    - the side pieces (8, 9) mechanically fixed to each other, the covers (10, 11), the tube sheets (6, 7) and the flat tubes (4) located in eyelets (5) of the tube sheets (6, 7) and turbulence inserts (17) located between the flat tubes (4) and the side pieces (8, 9) are taken to a soldering furnace and soldered there.

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