DE19907163C2 - Heat exchanger, in particular exhaust gas heat exchanger - Google Patents

Description

The invention relates to a heat exchanger, in particular an exhaust gas heat exchanger, held at both ends in tube sheets pipes for Guiding a gaseous medium and with a to the tube sheets closing and the tubes enclosing housing for guiding a liquid cooling medium, the tubesheets, the tubes and the housing are made of heat-resistant austenitic steel sheets, the pipes in welded from a sheet metal tube sheets are welded and the Housing is welded to the tube sheets.

A heat exchanger of the type mentioned is known from DE 195 40 683 A1 known.

The invention is based on the object, a heat exchanger of a The so-called type so that it is inexpensive and sweat can be produced technically advantageous.

This object is in a heat exchanger according to the preamble of claim 1 there solved by that the tube sheets are formed as deep-drawn parts, the one circumferential, the ends of the tubes of the tube bundle to the outside have superior wall, which is welded to the housing and on each connecting a diffuser.  

The inventive design of the heat exchanger allows a welding, in which in particular during welding the parts of the housing with the tube plates as little as possible heat me is introduced into the tube sheets, so that while a heat meverformung the tube sheets is largely prevented.

In an advantageous embodiment of the invention is provided that the housing and the tubesheets in the area of the circumferential Walls cut to length after making the welds are. In this way, a heat exchanger can create, with high accuracy, the required installation tolerances complies with who demanded especially in motor vehicles the.

In a further embodiment of the invention, it is provided that the housing and the tubesheets by means of a circumferential Auxiliary seam and by means of a closer to the pipe ends angerach th sealing seam are welded together, and that the Ge housing and the tubesheets in the area of the auxiliary seam cut to length are. The housing and tube sheets thus form a tight closed edge. Because the actual sealing seam is relatively close ge at the pipe ends receiving portion of the tube sheet it is largely excluded that in the Area between tube plate and housing a crevice corrosion occurs.

In an advantageous embodiment is further provided, that at the circumferential, cut edge each have a diffuser butt welded. This will be an advantageous Welded joint between the diffuser and the edge geschaf fen, in which sometimes even length tolerances out can be the same.

In a further embodiment of the invention, it is provided that the housing each subsequent to the tube sheets a grö ßeren cross-section than in the intermediate Be  rich, in which it envelops the pipes at a short distance. In the area of the larger cross sections, one is thus each one Art water tank created in which the liquid Cooling medium over the entire cross section of the heat exchanger distributed.

In a further embodiment of the invention, it is provided that the tubes with outwardly projecting, knob-like projections are provided, by means of which they among themselves and at the Inner wall of the housing are supported. He becomes one increased stability of the entire heat exchanger obtained, wherein at the same time the emergence of noise due to led vibrations or vibrations largely out is closed.

In a further embodiment of the invention, it is provided that the housing, composed of at least two sheet metal parts is set, by means of parallel to the tubes running Welded seams. Also when attaching this Welds are only small amounts of heat in the pipes or Tube bottoms initiated. Advantageously, it is provided that the welds in the area of the larger housing cross-section executed as an I-seam. This results in this Be rich a largely smooth outer contour of the heat exchanger. Appropriately, it is further provided that the welds in Area of smaller housing cross-section than flanged seam are executed. This makes it possible to weld the weld into the to undergo a total of one level. Especially before Partly it is when the housing parts elastically biased are welded. The elastic preload, on the one hand a dense application of the edges of the sheet to be welded causes parts, also ensures that the housing parts after welding in the area of the smaller housing cross cut under bias against the pimples of the outer Create tubes of the tube bundle, so that the risk of Ge noise is further reduced due to vibrations.  

This elastic bias consists essentially in Be rich in flanged seams.

In another embodiment of the invention is vorgese hen, that the housing is formed of a piece of pipe whose both end portions are widened. This will be a one-parti ger housing jacket created, the good at mounting handle is.

In a further embodiment of the invention, it is provided that the tubes by laser welding or electron beam Welded in the tube sheets are welded. To this Welding to be able to carry out exactly will continue hen that the tube sheets with at predetermined locations brought positioning aids are provided. This makes it possible Lich, the tube sheets with the pipes during welding ex align act.

In a further embodiment of the invention, it is provided that the tubes with a given supernatant into the tubesheets are plugged in, and that the welds next to the pipe outer walls by means of obliquely incident laser or Electron beam are attached. This measure is especial especially for larger heat exchangers of advantage, d. H. at Heat exchangers with a tube bundle of a variety of Pipes. With a large number of pipes, it is hardly possible exclude that when inserting the tubes in the Ausspa tion of the tubesheets latter are slightly deformed. This Deformation can occur by welding at an angle Ray encountered, so that the danger of an imperfect nen or leaking welding is largely avoided.

In a further embodiment it is provided that the housing in a region with the larger cross-section with an An end tube for a coolant supply and in the other Be rich with larger cross-section with a connecting pipe for egg ne coolant removal is provided, the housing with  outwardly directed passages is provided, to which the connecting pipes are welded. This also results in a cost-effective and welding technically advantageous solution for attaching the connections for the coolant.

Further features and advantages of the invention will become apparent from the following Description of embodiments.

Fig. 1 is a perspective view showing a heat exchanger according to the invention,

Fig. 2 is a partial section through the housing of the heat exchanger taken along the line II-II of Fig. 1,

Fig. 3 is a partial section through the housing of the heat exchanger taken along the line III-III of Fig. 1,

Fig. 4 position is a partial perspective view of the end portion of a heat exchanger before it inventive completion of its Her,

Fig. 5 is a partial section along the line VV of Fig. 4,

Fig. 6 shows a partial section along the line VI-VI of Fig. 1,

Fig. 7 shows a partial section in the area of connection between tubes and tube plate of a heat exchanger according to the invention,

Fig. 8 is a partial section similar to Fig. 7 with a scheduled supernatant of the tubes to the associated tube sheet,

Fig. 9 shows a section along the line IX-IX of Fig. 1,

Fig. 10 is a partial section similar to FIG. 9 of a abgewandel th embodiment,

Fig. 11 is a view of a housing jacket formed from a unitary piece of pipe and

Fig. 12 is a view of the housing shell in the axial direction Rich.

The partial sections are each on a larger scale darge provides.

The heat exchanger 11 shown in FIG. 1 is used in particular as an exhaust gas heat exchanger, in which exhaust gas is cooled. The exhaust gas flows through a diffuser 12 and is guided in the interior of the heat exchanger 11 by means of a tube bundle 13 of rectangular tubes to a diffuser 14 , from which it flows. In the area between the diffusers 12 , 14 , the tube bundle 13 is surrounded by a composite of two parts 15 , 16 translated housing, in which a liquid coolant is passed, which flows around the tubes of the tube bundle 13 . The coolant is supplied to a coolant inlet port 17 leads and discharged to a coolant drain port 18 , which are arranged substantially diametrically. The coolant flows in direct current to the exhaust gas to be cooled.

The tube bundle 13 consists of rectangular tubes, as they are known for example from DE 195 40 683 A1. The right eckrohre have protrude from opposite inner walls de, V-shaped tab pairs, which are alternately provided on gegenüberlie ing walls. The rectangular tubes are fer ner hen on its outer side with knob-like projections hen, where they are supported with each other and against the hous se 15 , 16 . The ends of the rectangular tubes of Rohrbün dels 13 are tightly welded into tube sheets 19 .

As tube plates 19 serve cup-shaped, deep-drawn sheet metal parts whose bottom is provided with a punched hole for receiving the tubes of the tube bundle 13 . Further, the tube plates 19 form a circumferential wall 20 which projects in the direction of the diffusers 12 , 14 over the ends of the tubes of the tube 13 Rohrbün. As will be explained in more detail below, the sheet metal moldings 15 , 16 forming the housing are welded to this wall 20 of the tubesheets 19 .

The housing is composed of two sheet metal parts 15 , 16 together. It has in each case to the diffusers 12 , 14 subsequent sequent areas 21 , 22 with a larger cross-section, each forming a ring-channel-like water distribution box, in the area on the one hand, the inlet port 17 and on the other hand, the drain port 18 are arranged. The central region of the housing between the two outer regions 21 and 22 has a smaller cross section. In this area, the housing keeps Ge a distance from the tubes of the tube bundle 13 , which is determined by the knob-like projections of the tubes. The sheet-metal parts 15 , 16 are connected by means of ver in the longitudinal direction of welding seams 23 . Each weld 23 is formed in the regions 21 , 22 of larger cross section than an I seam ( FIG. 3) and in the intermediate region of smaller cross section than a flanged seam ( FIG. 2). This ensures that each weld 23 runs at a constant height level and thus can be placed in a simple manner in a train. During welding of the welds 23 , the two sheet metal parts 15 are pressed against each other ge, so that the sheet metal parts in the region of the I-seam and in the region of the flanged seam are close to each other. The sheet metal parts 15 , 16 are slightly elastically deformed in the crimp seam, so that the housing in the middle, having a smaller cross-section Be rich after welding with a resilient bias on the knob-like projections of the tubes of the tube bundle 13 .

Before welding the longitudinal seams 23 , the sheet-metal shaped parts 15 , 16 are applied to the walls 20 of the tube plates 19 (FIGS . 4 and 5) which are provided with the tube bundle 13 . The welding of the longitudinal seams 23 also takes place in the region of the wall 20 of the tubesheets 19 , so that with the attachment of the welds 23, the tube plates 19 are tacked with the housing formed from the two sheet-metal shaped parts 15 , 16 . Subsequently, the housing formed from the two sheet-metal shaped parts 15 , 16 is welded to the tube plates 19 in the region of the walls 20 . Here, an auxiliary seam 24 is first attached at a greater distance to the bottom of the tube sheets 19 . Subsequently, a sealing seam 25 is welded, which is closer to the bottoms of the tube sheets 19 and preferably just before the transition between tween the wall 20 and the bottom of the tube sheets 19th

The welding of the rectangular tubes of the tube bundle 13 with the tubesheets 19 takes place before or after the attachment and welding of the housing. The tube plates 19 are attached to the ends of the rectangular tubes of the tube bundle 13 . Then who the ends of the rectangular tubes under plastic deformation widened something, so that only a small gap between the punched recesses of the tube plates 19 and the Rechteckroh ren is present, which allows a dense laser beam welding or electron beam welding. By means of the expansion, a joint connection between the tube bundle 13 and the tube plates 19 is provided , which allows the housing from the sheet metal parts 15 , 16 to attach and to weld, without the tubesheets 19 are already welded to the tube bundle 13 .

In Fig. 11 and 12, a housing shell 32 is shown, from which a heat exchanger 11 can be prepared in a corresponding manner. The housing shell 32 consists of a pipe section of a welded rectangular tube. The two end portions 33 , 34 are widened to form annular channel water distribution boxes. In these expanded areas connections for the water supply and water drainage are provided, for example, simple punched holes 35 , 36 or ge outwardly directed passages 28th If a particularly long pipe jacket 32 is provided, then it is expedient to stiffen it by means of outwardly formed transverse beads 37 , as shown in FIG. 11.

In this design, a tube bundle 13 is inserted from rectangular tubes in the housing shell 32 . Thereafter, tubesheets 19 are used, which are pressed into the flared end portions 33 , 34 before preferably with a slight interference fit. As a result, a joint connection is obtained before welding, which allows a good handling of the item so far mounted. Thereafter, the welding of the tubesheets 19 with the housing shell 32 in the end regions 33 , 34 by means of an auxiliary seam 24 and a sealing seam 25th Likewise, the rectangular tubes of the tube bundle 13 are welded to the tube plates 19 ver. It can optionally be provided that the welding of the tube plates 19 is performed with the rectangular tubes before or after the welding of the tubesheets 19 with the housing shell 32 .

The tubes of the tube bundle 13 have a relatively small wall thickness, ie a wall thickness in the order of 0.2 mm to 0.6 mm. It is therefore necessary that the laid around the tubes of the tube bundle 13 welds are very precisely introduced. For this purpose, it is necessary that the tube plates 19 are positioned with the tube bundle 13 very precisely to a Schweißvorrich device. In order to facilitate this positioning, the tubesheets 19 can be provided with positioning aids in a manner not shown.

As already mentioned, the welding of the tubes of the tube bundle 13 into the tubesheets 19 is preferably carried out as laser beam welding or as electron beam welding. If in a conventional manner, the welding is carried out so that the laser beam or electron beam, which is indicated in Fig. 7 with an arrow 26, is aligned parallel to the tube axes, so it should be ensured that in the Monta ge the tube plates 19 due deformations of the tube bottom no differences in position occur. In heat exchangers with a tube bundle 13 from a large number of tubes, often deflections and thus position displacements in larger dimensions than 0.1 mm can not be avoided. In this case, it is expedient to produce a supernatant when plugging the tube plates 19 onto the tube ends of the tube bundle 13 , as shown in FIG. 8. In this case, then the welding takes place by means of an obliquely directed laser beam or electron beam, which is indicated by the arrow 27 . The beam is inclined at a Win angle between 5 ° and 10 ° to the tube axis and directed to the tube sheet in the immediate vicinity of Rohraußenwandun conditions. When welding the tubes of the tube bundle 13 in the tube sheets 19 , the welds can be placed according to the pipe contour, ie as so-called window welding, or along the grid contour of the recesses of the tube sheet as so-called grid welding. If appropriate, it makes sense to provide in the area of the webs between opposite corners of the rectangular tubes a ring weld as additional seal welding or optionally applied to the webs of the tube plates 19 between the tubes still a weld as a cover layer.

After the main body of the heat exchanger 11 is completed, that is, after the housing has been attached and welded from the sheet metal moldings 15 , 16 and after the tube bundle 13 is welded into the tube plates 19 , or after the main body in the manner explained by means of the one-piece housing shell 32 has been shown in FIGS . 11 and 12 Herge, this main body of the heat exchanger 11 is cut to a predetermined extent, as shown in FIGS. 4 and 5. This cutting is preferably carried out in Be rich the auxiliary seam 24 by means of a laser cutter. Due to the cutting in the region of the auxiliary seams 24 remains a tightly closed edge of the front ends of the sheet metal moldings 15 , 16 and the wall 20 of the tube sheets 19th At this edge, the diffusers 12 and 14 are attached. Preferably, the diffusers 12 , 14 are butt-welded, as shown in Fig. 6. However, it is also possible to einzustec the diffusers ken in the peripheral edge or put on the outside of the peripheral edge and then welded to the inside of the wall 20 of the tube sheets 19 or outside with the sheet metal moldings 15 , 16 . The diffusers 12 , 14 can be produced as castings, deep-drawn parts or as welded parts. When mounting, they are set so that the tolerances incurred in their manufacture are compensated so far that the required installation dimensions for the ge entire heat exchanger 11 are met.

To form the coolant connections 17 , 18 , the sheet-metal shaped parts 15 , 16 are provided with passages 28 directed outwards. At these passages 28 , a connecting pipe is butt welded in the embodiment of FIG. 9. This welding can be carried out for example by means of a TIG welding with an orbital welding gun. In the embodiment of FIG. 10, the connecting pipe 30 is provided with a umlau fenden bead 31 and inserted into the passage 28 . In the Fügebe rich welding takes place. This welding can be carried out, for example, as a TIG welding with a robot.

For the tubes of the tube bundle 13 and the tubesheets 19 , a heat-resistant austenitic steel is selected, which is especially resistant to corrosion in a gas containing sulfuric acid from a large extent. For the sheet metal parts 15 , 16 of the housing, a heat-resistant austenitic steel is also provided. The tubes of the tube bundle 13 have a relatively small wall thickness, for example in the order of 0.2 mm to 0.6 mm, since in their area the heat transfer between the exhaust gas and the liquid coolant takes place. On the other hand, the tube plates 19 and the sheet metal shaped parts 15 , 16 or the housing jacket 32 can have a significantly greater wall thickness, for example of the order of magnitude of 1 mm. The welding of the sheet metal parts 15 , 16 with each other and with the tube plates 19 and the welding of the diffusers 12 , 14 can also be carried out as laser beam welding. But there are also other welding methods used, for. As electron beam welding, MIG welding, TIG welding or plasma welding.

Claims (16)

1. heat exchanger, in particular exhaust gas heat exchanger, with at both En held in tube sheets tubes for guiding a gaseous medium and with a subsequent to the tube plates and enclosing the pipes Ge housing for guiding a liquid cooling medium, the tube sheets, the tubes and the housing heat-resistant, austenitic steel sheets are formed, the tubes are welded into the sheet metal stamped tubesheets and the housing is welded to the tube plates, characterized in that the tube plates ( 19 ) are formed as deep-drawn parts, each of which revolve de, the ends the tube of the tube bundle ( 13 ) outwardly projecting wall ( 20 ) which is welded to the housing ( 15 , 16 , 32 ) and to each of which a diffuser ( 12 , 14 ) connects. 2. Heat exchanger according to claim 1, characterized in that the housing ( 15 , 16 , 32 ) and the tube plates ( 19 ) in Be rich of the peripheral walls ( 20 ) are cut to length after the production of welded joints. 3. Heat exchanger according to claim 2, characterized in that the housing ( 15 , 16 , 32 ) and the tube plates ( 19 ) by means of a peripheral auxiliary seam ( 24 ) and by means of a closer attached to the tube ends sealing seam ( 25 ) are welded together ver, and that the housing and the tubesheets ( 19 ) in the region of the auxiliary seam ( 24 ) are cut to length. 4. Heat exchanger according to claim 3, characterized in that on the peripheral, cut-edge each have a diffuser ( 12 , 14 ) butt welded. 5. Heat exchanger according to one of claims 1 to 4, characterized in that the housing ( 15 , 16 , 32 ) respectively at closing to the tube sheets ( 19 ) has a region ( 21 , 22 , 33 , 34 ) with a cross section, the larger than the cross-section in the intermediate region, in which the housing, the tubes of the tube bundle ( 13 ) stood at a low level. 6. Heat exchanger according to claim 5, characterized in that the tubes of the tube bundle (13) being provided outwardly projecting, knub-like projections, by means of which they are to each other and to the inner wall of the housing (15, 16; 32) are supported. 7. Heat exchanger according to one of claims 1 to 6, characterized in that the housing, which is composed of at least two sheet metal parts ( 15 , 16 ), by means of paral lel to the tubes of the tube bundle ( 13 ) extending weld seams ( 23 ) is welded , 8. Heat exchanger according to claim 7, characterized in that the welds in the areas ( 21 , 22 ) are designed with a larger cross-section than I-seam. 9. Heat exchanger according to claim 7 or 8, characterized in that the welds ( 23 ) are designed in the region of the smaller housing cross section as flanged seam. 10. Heat exchanger according to one of claims 7 to 9, characterized in that the housing parts ( 15 , 16 ) are elastically welded in front of tense. 11. Heat exchanger according to one of claims 1 to 6, characterized in that the housing ( 32 ) has a housing shell of a pipe section, whose two end portions ( 33 , 34 ) are widened. 12. Heat exchanger according to one of claims 1 to 11, characterized in that the tubes of the tube bundle ( 13 ) are welded by means of laser beam welding or electron beam welding in the tube sheets ( 19 ). 13. Heat exchanger according to claim 12, characterized in that the tube plates ( 19 ) are provided with predetermined positions is placed positioning. 14. A heat exchanger according to claim 12 or 13, characterized in that the tubes of the tube bundle ( 13 ) are inserted with a pre-given projection into the tube sheets ( 19 ), and that the welds ( 23 ) immediately adjacent to the Rohraußenwän the means incident obliquely Laser beam or electron beam ( 27 ) are mounted. 15. Heat exchanger according to one of claims 1 to 14, characterized in that the housing ( 15 , 16 , 32 ) in a region ( 21 , 33 ) with a larger cross-section with a connection pipe ( 29 , 30 ) for a coolant supply ( 17 ) And in the walls ren region ( 22 , 34 ) with a larger cross section with a con nection pipe ( 29 , 30 ) for a coolant discharge ( 18 ) is provided. 16. A heat exchanger according to claim 15, characterized in that the housing ( 15 , 16 , 32 ) is provided with outwardly directed passages ( 28 ) are welded to the connecting pipes ( 29 , 30 ).