EP0225533B1 - Plate heat exchanger - Google Patents

Description

The invention relates to a surface heat exchanger according to the preamble of claim 1.

Surface heat exchangers are known (DE-GM-8 304 603), in which meandering bent coils are provided, which are fastened to carrier plates, which preferably consist of aluminum or wrought aluminum alloys, in that cramps are punched out of the plane of the carrier plates and around the pipes are lying around. The pipes fixed to the plate in this way, which have a triangular cross section for better fastening, can then be covered by a second plate. It is disadvantageous in these designs that the eyelets and holding cramps pose a risk of injury when installing such a surface heat exchanger, which is why the second cover plate must also be provided, as a rule, and that the heat transfer between the pipe and plate is not due to the relatively small contact surfaces between the cramps and the pipe is sufficient.

It is also known to manufacture surface heat exchangers in this way (DE-OS-3 308329). that the coil is glued to the support plate. A disadvantage here is the poor heat transfer between the coil and plate, because the adhesive has only a low thermal conductivity. It is also disadvantageous that the tube coil and carrier plate have to remain clamped to one another during the curing process of the adhesive. This is cost-intensive and, due to the curing time, series production does not appear to make sense. In addition, such an adhesive connection for highly stressed products, such as for use in motor vehicles, is not reliable enough.

Finally, it is also known a surface heat exchanger of the type mentioned (DE-PS-575 272), in which pipes are welded into slots in a carrier plate, in such a way that the edges of the slots touch the tube at diametrical locations of the diameter, so that half of the pipe circumference protrudes on both sides of the support plate or so that the larger circumference and the smaller circumference of the pipe protrude on one side of the support plate. In both cases, in which the pipes are to be closed at their ends, a relatively good heat transfer from the pipes to the carrier plate can be achieved. The manufacturing process is still relatively complex because of the necessary welding or soldering process.

The invention is therefore based on the object of designing a surface heat exchanger of this type in such a way that the manufacture does not require a welding or soldering process, but still ensures good heat transfer between the tube and the carrier plate.

To solve this problem, the characterizing features of claim 1 are provided in a surface heat exchanger of the type mentioned.

This configuration creates continuous contact surfaces between the tube and the support plate on opposite outer sides of the tube, which ensure a heat transfer that is as good as that between the fins attached to a tube. However, the production of the new surface heat exchanger does not require a welding, gluing or soldering process and can be carried out in a simple manner. The heat transfer between the tube and plate can also be improved in that the width of the slots is selected to be somewhat smaller than the tube diameter. As a result, a certain deformation of the tubes and the slot edges occurs already when the tubes are positioned in the slots in the plate. If the pipes are provided with pinch folds, which each overlap the opposite cut edges, a stable positive connection is created in addition to the frictional connection between the pipe and the slots. The new surface heat exchanger can be designed to be extremely stable and has excellent heat transfer properties.

It is advisable not to let the slots for inserting the pipe or coil pass through to the edge of the plate. In this case, at least the two connecting ends of the pipe are bent out at the level of the plate. The plate itself can therefore be kept stable because the slots for inserting the tube or the coil are only inside the plate surface, so that it can keep a rigid peripheral edge.

It can be advantageous if the tube is formed in a serpentine shape with straight legs running parallel to one another, to keep only these legs in parallel slots within the plate, while - in addition to the connecting ends - the connecting bends of these legs also protrude cranked out of the plane of the plate and onto just rest on the plate. It has been shown that the resulting loss of heat-transfer contact surfaces is not so critical that the simplifications in production could not outweigh this. Above all, in this embodiment it is very simple to provide the pinch folds in the area of the parallel slots continuously on both sides of the plate, so that the tube in the area of its parallel legs not only on the end faces of the slot edges, but also on the slot via the pinch folds adjoining edge areas of the plate so that this significantly increases the heat transfer area here.

In another embodiment, the slots can be interrupted by transverse webs, which are deformed when the tubes are inserted, or even previously in a semicircular manner, the tube then being provided with the pinch folds only on the side of the plate opposite the transverse webs. Such a configuration can also be provided, for example, in the region of the connecting bends of the serpentine tube, so that it is not necessary to lead the connecting bends out of the plate plane in a cranked manner. Nevertheless, in this way, in the area of the connecting bends, there is no need to provide a pinch fold arrangement running on both sides, the manufacture of which is possible, but is not necessarily expedient in view of a later bending of the plate for adaptation to installation conditions.

In a third embodiment, finally, the deformations can be applied along the tube only at points at intervals in succession, with adjacent deformations also being arranged alternately on one or the other side of the tube protruding from the plate plane. This embodiment has the advantage that the tube can be fastened in this way largely independently of tolerance in the slot, even in the region of the connecting bends of serpentine tubes. With this type of deformation of a tube in the form of a snake, the slot can therefore also have a shape adapted to this snake shape.

For the manufacture of the new surface heat exchanger, a device according to the dependent claims 10 to 12 has proven to be particularly advantageous, with devices according to these features first of all positioning the pipe coil in the carrier plate and then also fastening it in a form-fitting manner.

• Fig. 1 die schematische Draufsicht auf einen Flächenwärmetauscher gemäß der Erfindung mit einem Rohr in Schlangenform,
• Fig. 2 den Teilschnitt durch den Flächenwärmetauscher der Fig. 1 längs der Linie 11-11 in vergrößertem Maßstab,
• Fig. 3 den Teilschnitt durch die Fig. 1 längs der Linie III-III, ebenfalls in vergrößertem Maßstab,
• Fig. 4 die Teildraufsicht auf einen Flächenwärmetauscher gemäß der Erfindung, bei dem die Schlitze zum Einsetzen der Rohrschlangenteile durch Querstege unterteilt sind,
• Fig. 5 den Teilschnitt durch den Wärmetauscher der Fig. 4 längs der Linie V-V,
• Fig. 6 die Draufsicht auf einen Flächenwärmetauscher ähnlich der Fig. 1, jedoch mit einer nur punktweise in Schlitzen der Platte befestigten Rohrschlange,
• Fig. 7 den Schnitt durch den Flächenwärmetauscher der Fig. 6 längs der Linie VII-VII,
• Fig. 8 den Teilschnitt durch den Flächenwärmetauscher der Fig. 6 längs der Linie VIII-VIII,
• Fig. 9 eine schematische Darstellung einer Vorrichtung zur Herstellung eines Flächenwärmetauschers gemäß Fig. 6,
• Fig. 10 die schematische Stirnansicht des bei der Vorrichtung der Fig. 9 verwendbaren Verformungsstempels,
• Fig. 11 eine Stirnansicht gemäß Fig. 10, jedoch von einem Verformungsstempel mit einem anders ausgebildeten Stirnende,
• Fig. 12 die Ansicht einer Verformungsstelle des Rohres des Flächenwärmetauschers der Fig. 6 in Richtung des Pfeiles XII der Fig. 8 gesehen, die bei Verwendung des Verformungsstempels der Fig. 10 entstanden ist und
• Fig. 13 die Ansicht gemäß Fig. 12 einer Verformungsstelle eines Rohres, die jedoch unter Verwendung eines Verformungsstempels mit der Stirnseite der Fig. 11 hergestellt wurde.

In the drawing, the invention is illustrated using exemplary embodiments and explained in the following. Show it:

• 1 is a schematic plan view of a surface heat exchanger according to the invention with a tube in the form of a snake,
• 2 shows the partial section through the surface heat exchanger of FIG. 1 along the line 11-11 on an enlarged scale,
• 3 shows the partial section through FIG. 1 along the line III-III, also on an enlarged scale,
• 4 shows the partial top view of a surface heat exchanger according to the invention, in which the slots for inserting the pipe coil parts are divided by transverse webs,
• 5 shows the partial section through the heat exchanger of FIG. 4 along the line VV,
• 6 is a top view of a surface heat exchanger similar to FIG. 1, but with a pipe coil which is fastened only at certain points in the plate slots,
• 7 shows the section through the surface heat exchanger of FIG. 6 along the line VII-VII,
• 8 shows the partial section through the surface heat exchanger of FIG. 6 along the line VIII-VIII,
• 9 shows a schematic illustration of a device for producing a surface heat exchanger according to FIG. 6,
• 10 shows the schematic end view of the deformation die that can be used in the device of FIG. 9,
• 11 is an end view according to FIG. 10, but of a deformation die with a differently designed end,
• Fig. 12 seen the view of a deformation point of the tube of the surface heat exchanger of Fig. 6 in the direction of arrow XII of Fig. 8, which was formed when using the deformation stamp of Fig. 10 and
• FIG. 13 shows the view according to FIG. 12 of a deformation point of a tube, which, however, was produced using a deformation stamp with the end face of FIG. 11.

In Fig. 1, four parallel slots 3, 4, 5 and 6 are arranged in a plate 1, for example made of aluminum, each of which does not pass through to the edge 1a of the plate. In the embodiment shown, the slots 3 and 6 are formed somewhat longer than the slots 4 and 5. The slots 3 and 6 each run on their left side up to the dashed line 20, from which the slots 4 and 5 also extend. On their right side, however, the slots 3 and 6 extend up to approximately the boundary line 22, while the slots 4 and 5 only extend up to the indicated boundary line 21.

In these parallel to each other slots 3, 4, 5 and 6 the straight legs 2 ', 2 ", 2'" and 2 "" of a tube 2 bent in a snake shape are inserted in such a way that the tube 2 is at diametrically opposite points of its Diameter is held between the opposing slot edges 8. The two open connection ends 2b, 2c are cranked out of the plane of the plate 1, as shown in FIG. 3 with reference to one of the connection ends 2b. If the connection in the bend area is problematic with certain pipe shapes, which is however regarded as an exception, the connecting bends 2d between the legs 2 ', 2 "or 2'" and 2 "" can also be led out of the plate plane.

The width b of the slots 3, 4, 5 and 6 in the illustrated embodiment is chosen to be somewhat smaller than the diameter d of the tube 2, which is only indicated in FIG. 7, so that, as shown in FIG. 2 emerges, the tube 2, which has received an oval shape before the pressing in of its straight legs into the slots 3, 4, 5 and 6, which is denoted by 2e in FIG. 2, is pressed into the slots and with its widest point is tight against the opposite slot edges 8. The tube 2 is also in contact with these slot edges, which enables good heat transfer between the heat exchange medium which is later passed through the tube 2 and the adjacent plate 1. As can be seen in FIG. 2, the axis of the tube 2 in its position 2e runs in the central plane of the plate 1. In the following, it will be said for this arrangement that the tube lies in the plate plane.

As can also be seen from FIG. 2, the position 2e of the tube 2 is not the final shape for the form-fitting attachment of the tube 2 in the slots in the plate. Rather, in the exemplary embodiment, the pipe legs 2 ', 2 ", 2"' and 2 "" are continuously provided with deformation 7 from both sides of the plate, which in each case lead to continuous flattening on both sides of the pipe, but in the area of the slot edges 8 but pinch folds 9 generate, which engage around the slot edges 8 from both sides. The tube thus squeezed sits positively and firmly in the plate 1. The contact surfaces between plate 1 and tube 2 are much larger than the end faces of the slot edges 8 due to the pinch folds 9 and their contact surfaces on the plate 1, so that an excellent operation Heat transfer is possible. Of course, it would also be possible to squeeze only the straight and parallel pipe legs because this is easier to manufacture. So while in the surface heat exchanger shown in Fig. 1, the pipe legs 2 ', 2 ", 2"' and 2 "" are in the plate plane, the connecting bends 2d are either up or down out of this plate plane, so that they either open the side of the connection ends 2b, 2c or on the opposite side of the plate 1.

4 and 5, a modified embodiment of a surface heat exchanger is shown, insofar as here, which is also possible in principle in the embodiment of FIG. 1, a single continuous slot adapted to the snake shape of the tube 2 is provided, which consists of the straight sections 3 ', 4' and the arcuate connecting these two slit parts 23. In this continuous slot, the serpentine tube 2, with the exception of its connecting ends 2b, which protrude from the plane of the plate in a similar manner to FIG. 3, is inserted so that the coil lies in the plane of the plate. In the embodiment of FIG. 4, the securing of the tube 2 in this position is carried out by transverse webs 10 which divide the slots 3 ', 23 and 4' and which are deformed semicircularly downwards before or when the tube 2 is inserted. The deformation can also take place in such a way that the tube 2 reaches the region of the crosspieces 10 with a little more than half of its circumference, so that it is held firmly in this position due to the deformation occurring when it is inserted. The top of the tube 2 can again be provided with deformations 7 in the form of a continuous flattening, so that the pinch folds 9 form, which rest on the plate 1 from the top. In addition, it is possible to fix the pipe bends 2d on the side facing away from the crosspieces 10 in that clamping tabs 24 are punched out of the plate 1 and partially placed over the circumference of the pipe in the region of the connecting bend 2d. A similar fixation is also conceivable for the connection ends 2b.

Another and extremely advantageous variant of a surface heat exchanger is shown in FIGS. 6 to 8. Here, as in FIG. 4, the serpentine slot arranged within the plate 1 corresponds to the serpentine shape of the tube 2. In this case, too, the slot is arranged exclusively within the plate and a peripheral edge 1a remains. The connection ends 2b and 2c are also led out of the plate level in this embodiment, as shown in Fig. 3. The connection ends 2b and 2c are secured here in the area of the edge 1a of the plate by riveted tabs 19. The pipe 2, with the exception of its connecting ends 2b and 2c, which runs completely in the plate plane, is not provided in this exemplary embodiment with continuous pinches over the entire length of the tube, but only with pinches 7a provided at points, which, as shown in FIGS. 7 and 8 in individual can be seen, each arranged along the tube 2 at a distance from one another and are designed such that adjacent pinch points 7a with the resulting pinch folds 9 are each provided on opposite sides of the plate 1 on the tube 2, which thus inside with is alternately provided with constrictions protruding into the free cross section. These alternating constrictions act on the flowing heat exchange medium in the manner of flow baffles, which excite the flowing medium to turbulence and therefore ensure the improvement of the heat transfer coefficient. The alternate squeezing through the squeezing points 7a is sufficient to bring about a secure fastening of the tube 2 over its entire length in the plate plane. It is advantageous that 2d pinch points are also provided in the area of the connecting bends. The intimate contact of the outer tube walls with the slot edges 8, the is also present in the area of the tube sheets 2d, ensures sufficient heat transfer between tube and plate 1.

9 to 11 a device for producing a surface heat exchanger according to FIGS. 6 to 8 is shown schematically. The device consists of two mutually movable blocks 13 and 14, between which the plate 1, previously provided with the punched-out slots, is inserted with the serpentine tube 2. The serpentine tube 2 has not yet been brought into the position shown in FIG. 9. The serpentine tube 2 is initially when the blocks 13 and 14 have moved apart above the plate level and only protrudes with a part of its respective circumference into the punched slots. The blocks 13 and 14 each have recesses 15 at the location of the slots or at the location where the tubes 2 are pressed into the slots, which correspond to the course of the pipe coil and the course of the slots and have a cross section that is approximately corresponds to half the contour of the tube 2 to be used.

In the exemplary embodiment shown, the recesses 15 therefore have a semicircular cross section. If the blocks 13 and 14 are therefore moved together until they abut the sheet metal 1, the round tube 2 is simultaneously pushed into the plate plane and, similarly as already described with reference to FIG. 1, between the diametrically opposite slot edges 8 jammed at its widest point.

In blocks 13 and 14, holes 25 with punches 12 guided therein are provided along the recesses 15 at a corresponding distance, which can be acted upon from outside with a force in a manner not shown and can be pressed in the direction of tube 2. Such stamps 12, as shown, are provided both in the upper block 13, and - in a manner not shown - in the lower block 14, so that by pressing these stamps 12, as can be seen from FIGS. 6 to 8, punctiform Squeezes 7a can alternately be attached to the tube 2 on both sides. Depending on the shape of the end face 26 of the stamp 12, the pinch points 7a are given different shapes. If, for example, a stamp 12 'with an end face 27 according to FIG. 10 is used, which is approximately rectangular in shape and merges backwards into the cylindrical part 29 through inclined surfaces 28, then pinch points 7a arise on the two tube sides, which roughly correspond to the appearance Fig. 12. If, however, a stamp 12 "is provided with a circular end face 30 which runs perpendicular to the cylindrical part 29, then pinch points 7a are formed which, viewed perpendicularly to the plate plane, have the appearance according to FIG. 13. The pinch points 7a according to FIG. 13 result longer creases 9 "which can overlap the plate than in the example of FIG. 12, where the creases 9 'remain relatively short. However, the squeezing forces to be applied are lower in the example of FIG. 12. If necessary, the distance between the alternating pinch points can be chosen to be smaller than in the example according to FIG. 13 if the heat-transferring surface between the tube and the plate is to be kept as large as possible.

Instead of the type of fastening shown by pinching, a combination of such pinching and continuous pinching would of course also be possible, for example pinpointing in the area of the pipe bends and continuous pinching of the tube in the area of its straight legs.

Claims (12)

1. A panel heat exchanger consisting of a plate (1) of heat conductive material and at least one pipe connected thereto and being in particular of serpentine form, through which flows a heat exchange medium, the plate being provided with slots (3, 4, 5, 6, 23) the width of which is adapted to the diameter of the pipe (2) and into which the pipe is inserted, characterised in that at diametrically opposed points of its diameter (d), the pipe (2) is held between oppositely disposed edges (8) of the slots (3, 4, 5, 6, 23) and comprises on both sides of the plate (1) transversely to its longitudinal axis shaped portions (7) with creases (9) which the edges (8) of the slots engage around from both sides, in form-locking fashion.

2. A panel heat exchanger according to Claim 1, characterised in that the width (b) of the slots (3, 4, 5, 6, 23) is somewhat smaller than the diameter (d) of the pipe (2).

3. A panel heat exchanger according to Claims 1 and 2, characterised in that the slots (3, 4, 5, 6) do not extend as far as the edge (1 a) of the plate (1) and in that the pipe (2) has at least its two connecting ends (2b, 2c) cranked away from the plane of the plate (1).

4. A panel heat exchanger according to Claims 1 to 3, characterised in that the pipe (2) is of serpentine construction, having mutually parallel straight portions (2', 2", 2"', 2"") and in that only the straight portions are supported in parallel slots (3,4, 5, 6) while the connecting bends (2d) are cranked away from the plane of the plate (1).

5. A panel heat exchanger according to Claims 1 to 4, characterised in that the creases (9) are provided in the region of the slots (3, 4, 5, 6) continuously and on both sides of the plate (1).

6. A panel heat exchanger according to one of Claims 1 to 3, characterised in that the slots (3) are interrupted by transverse webs (10) which are given a half-round shape upon insertion of the pipe (2) and in that the pipe has creases (9) only on that side of the plate (1) which is opposite the transverse webs (10).

7. A panel heat exchanger according to one of Claims 1 to 3, characterised in that the shaped portions (7) are disposed punctiformly at intervals one after another along the length of the pipe (2).

8. A panel heat exchanger according to Claim 7, characterised in that adjacent shaped portions (7) are disposed alternately on the side of the pipe (2) or the other, projecting from the plane of the plate.

9. A panel heat exchanger according to Claim 7 and 8, characterized in that the pipe (2) is bent in serpentine fashion and in that a slot (3, 4, 5, 6, 23) is provided which is adapted to the serpentine form of the pipe and in which also the pipe bends (2d) are accommodated substantially flush with the plane of the plate.

10. An apparatus for producing a panel heat exchanger according to Claim 1, characterised by a support (11) for the plate (1) and by at least one dye (12) for positioning and shaping the pipe (2) and adapted for movement in respect of the support.

11. An apparatus according to Claim 10, characterised in that the support consists of two oppositely disposed movable blocks (13, 14) of which at least one is provided with a depression (15) matching the shape of the pipe and disposed opposite the die (12).

12. An apparatus according to Claim 11, characterised in that each of the blocks (13, 14) is provided with the depressions (15) and in that lengthwise of these depressions and adapted for movement transversely thereto there are in each of the blocks a plurality of dies (12) for the punctiform shaping of the pipe (2) and of which those dies associated with the oppositely disposed blocks are in each case staggered in respect of one another in the direction of the depressions.

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