Abstract
A heat-conducting plate for fixing a pipe section to a holding surface of a heat exchanger, wherein the heat-conducting plate has perforations, in particular for acoustic reasons, wherein the perforations are not distributed uniformly over the entire surface of the heat-conducting plate.
Claims
1-15. (canceled)
16. A heat-conducting plate for fixing a pipe section to a holding surface of a heat exchanger, wherein the heat-conducting plate comprises perforations that are not distributed uniformly over an entire surface of the heat-conducting plate.
17. The heat-conducting plate according to claim 16, wherein the perforations are for acoustic purposes.
18. The heat-conducting plate according to claim 16, further comprising a central section and at least one side section.
19. The heat-conducting plate according to claim 18, wherein the central section has a bead.
20. The heat-conducting plate according to claim 19, wherein the bead is arranged to cooperate with the pipe section.
21. The heat-conducting plate according to claim 18, wherein the at least one side section bears against the holding surface.
22. The heat-conducting plate according to claim 18, wherein the side section comprises more perforations per surface unit than the central section.
23. The heat-conducting plate according to claim 18, wherein the perforations are substantially formed in the at least one side section.
24. The heat-conducting plate according to claim 23, wherein the perforations are all formed in the at least one side section.
25. The heat-conducting plate according to claim 18, wherein the perforations are arranged inside an enveloping contour of the heat-conducting plate.
26. The heat-conducting plate according to claim 25, wherein the enveloping contour is formed by straight lines.
27. The heat-conducting plate according to claim 16, wherein the perforations are each at least partially formed as outwardly open edge recesses at an edge of the heat-conducting plate.
28. The heat-conducting plate according to claim 27, wherein a majority of the perforations are formed as outwardly open edge recesses.
29. The heat-conducting plate according to claim 28, wherein all of the perforations are formed as outwardly open edge recesses.
30. The heat-conducting plate according to claim 27, wherein the perforations form tongues in the heat-conducting plate.
31. The heat-conducting plate according to claim 18, wherein the at least one side section includes two side sections that, at least in an unbuilt state, are arranged at an incidence angle to one another, in particular for the purpose of later pre-tensioning on the holding surface.
32. The heat-conducting plate according to claim 16, further comprising holding means for attaching the heat-conducting plate to the holding surface, the holding means being arranged in a region of the heat-conducting plate without perforations.
33. The heat-conducting plate according to claim 32, wherein the holding means is a double-sided adhesive tape.
34. A heat exchanger, comprising: a pipe section; a holding surface; and a heat-conducting plate according to claim 16, wherein the heat-conducting plate fixes the pipe section to the holding surface.
35. A method for producing a heat-conducting plate for fixing a pipe section to a holding surface of a heat exchanger, comprising the step of forming outwardly open edge recesses on the heat-conducting plate.
Description
[0139] Further advantages of the invention result from the are apparent from the sub-claims not mentioned and from the following description of the exemplary embodiments shown in the figures. In the figures:
[0140] FIG. 1 shows a highly schematic sectional view of a surface heat exchanger according to the invention arranged on a building ceiling, with an exemplary view of two heat-conducting plates according to the invention,
[0141] FIG. 2 shows a schematic sectional view, omitting essential elements, of the arrangement of three surface heat exchangers according to the invention in one room,
[0142] FIG. 3 shows a highly schematic, oblique perspective view of an inner edge region of a surface heat exchanger according to the invention, approximately according to view arrow Ill in FIG. 1, but omitting a carrier plate,
[0143] FIG. 4 shows a highly schematic view of a blank for producing a heat-conducting plate according to the invention,
[0144] FIG. 5a shows a view somewhat according to FIG. 4 of a further processed blank, after the use of a nibbler to make a perforation on the edge or to form tongues on the edge,
[0145] FIG. 5b shows a schematic sectional view, somewhat along the section line Vb-Vb, of the body shown in FIG. 5a,
[0146] FIG. 6a shows a view according to FIG. 5a of the blank shown in FIG. 5a after carrying out an embossing process to insert a bead,
[0147] FIG. 6b shows a view according to FIG. 5b of the blank shown in FIG. 5b after carrying out an embossing process to insert a bead,
[0148] FIG. 6b shows a view according to FIG. 6b of an alternative, slightly modified heat-conducting plate with pre-tensioned side regions,
[0149] FIG. 7a shows a view according to FIG. 6a of the heat-conducting plate according to the invention according to FIG. 6a with the pipe section inserted into the bead,
[0150] FIG. 7b shows a view according to FIG. 6b of the heat-conducting plate according to the invention according to FIG. 6b with the pipe section inserted into the bead,
[0151] FIG. 7c shows a view according to FIG. 7b of an alternative, slightly modified heat-conducting plate with pre-tensioned side regions,
[0152] FIG. 8a shows the device according to FIG. 7a with double-sided adhesive tape applied,
[0153] FIG. 8b shows the device according to FIG. 7b with double-sided adhesive tape applied,
[0154] FIG. 8c shows a view according to FIG. 8b of an alternative, slightly modified heat-conducting plate with pre-tensioned side regions,
[0155] FIG. 9 shows a view according to FIG. 5a of an alternative design of perforations, which in this exemplary embodiment are not formed as outwardly open edge recesses, but as closed edge recesses,
[0156] FIG. 10 shows a highly schematic, oblique perspective view of an exemplary section of an alternative, slightly modified heat-conducting plate with raised intermediate tongues,
[0157] FIG. 11a shows a view according to FIG. 6a of a complete heat-conducting plate according to FIG. 10 with the pipe section inserted into the bead,
[0158] FIG. 11b shows a highly schematic front view of the heat-conducting plate of FIG. 11a in a bottom view together with the pipe section, approximately along view arrow XIb in FIGS. 10 and 11a,
[0159] FIG. 11c shows a view according to FIG. 11b of an alternative, slightly modified heat-conducting plate with pre-tensioned side regions, and
[0160] FIG. 12 shows a view somewhat according to FIG. 11b of an alternative, slightly modified heat-conducting plate with a larger elevation angle of the intermediate tongues, additionally showing or indicating the holding surface.
[0161] Exemplary embodiments of the invention are described in the following figure description, additionally with reference to the drawings. For the sake of clarity—also as far as different embodiments are concerned—identical or comparable parts or elements or regions are designated with the same reference numerals, sometimes with the addition of lowercase letters, numbers and/or apostrophes. The same applies to the claims following the figure description.
[0162] Features described only in relation to one embodiment may also be provided in any other embodiment of the invention within the scope of the invention. Such modified embodiments—even if not shown in the drawings—are covered by the invention.
[0163] All disclosed features are essential to the invention in themselves. The disclosure of the application hereby also includes in full the disclosure content of any associated priority documents (copy of the prior application) as well as any cited publications and the described prior art devices, also for the purpose of including individual or several features of these documents in one or several claims of the present application.
[0164] FIG. 1 first shows an example of a (surface) heat exchanger 10 of the cassette type according to the invention. In the embodiment shown, a carrier plate 11 is inserted into a cassette 12, which in turn is arranged on a room ceiling 15. The carrier plate 11 is stuck to the inside of the cassette on its underside and lies approximately centrally. A pipe system with pipe sections 13 is arranged on the carrier plate 11 and fastened with the aid of, in particular strip-like, heat-conducting plates 14 or 14′ according to the invention.
[0165] In the exemplary embodiment shown, the strip-like heat-conducting plate 14, 14′ overlaps the pipe 13 and is firmly arranged, in particular stuck, to the carrier plate 11 via holding means (not shown).
[0166] For the sake of completeness, it should be noted that configurations exist with or without the carrier plate 11. Alternatively, the pipe system 13 and the heat-conducting plates 14, 14′ could also be stuck directly to the inside 17 of the end face of the cassette 12. Both configurations are covered by the invention.
[0167] As shown in FIG. 2, several surface heat exchangers 10 according to the invention can be mounted, for example, in the region of the ceiling 15 of a building room 16 in order to air-condition the room 16 on the ceiling side. The air conditioning can in particular serve to heat or alternatively cool the room 16. In particular, for optical reasons, surface heat exchangers of the cassette type are often used for such requirements, in which the actual functional components of the surface heat exchanger 10, such as the heat-conducting plate or pipe system, are arranged in a holding cassette 12.
[0168] FIG. 2 shows a surface heat exchanger system consisting of three surface heat exchangers 10a, 10b and 10c, the holding cassettes of which are arranged next to one another essentially in a cascade.
[0169] For reasons of clarity, for example, the pipe system is not shown in FIG. 2. However, the pipes of all three heat exchangers 10a, 10b, 10c can, for example, be assigned a common inflow and outflow.
[0170] Not visible in FIG. 1 as well as in FIG. 2 are acoustic perforations of the holding cassette(s) 10 or of the carrier plate 11 and in particular also perforations of the heat-conducting plates according to the invention. Although these could in principle be shown in cross-sectional views according to FIGS. 1 and 2, they would jeopardize the clarity of the figures, which is why they have been omitted from FIGS. 1 and 2, such that FIGS. 1 and 2 initially only serve to illustrate a basic arrangement of a heat exchanger or heat-conducting plates according to the invention.
[0171] FIG. 3 then provides a more detailed description of the invention, in particular of the arrangement of the perforations in the heat-conducting plate according to the invention.
[0172] FIG. 3 shows here in a highly schematic, oblique isometric view a partial region of a heat exchanger 10 according to the invention, which partial region in FIG. 1 is provided with the view arrow Ill (in particular omitting the ceiling 15).
[0173] Only for reasons of disclosure, the heat exchanger 10 according to FIG. 3 has two differences to the one according to FIG. 1. These differences may or may not be optional in a heat-conducting plate or heat exchanger according to the invention. Therefore, the elements of the heat exchanger are provided with the same reference numerals in both figures.
[0174] Firstly, as shown in FIG. 3, the pipe system or the pipe section 13 has a D-shaped cross-section (in contrast to a round shape as shown in FIG. 1). Such a shape is typical in particular for pipes of the applicant, but the invention can also be used without further ado for other pipe cross-sections.
[0175] Secondly, the carrier plate 11 shown in FIG. 1 is not provided in FIG. 3. This means, therefore, that a heat-conducting plate 14 according to the invention can fix a pipe section 13 either directly to the inner side 17 of the cassette 12 or alternatively, as shown in FIG. 1, indirectly, namely via a carrier plate 11, for example, to which the pipe system 13 is then directly fixed by the heat-conducting plate 14. In other words, depending on the requirements, the heat-conducting plate 14 together with the pipe system or pipe section 13 can be stuck directly into the retaining cassette or (initially) onto a carrier plate 11, which is then inserted into (and fixed in) the cassette 12.
[0176] Viewing FIG. 3 shows that the holding cassette 12 has an acoustic perforation 18, which consists of numerous holes 19.
[0177] These serve to absorb sound through the cassette 12, in that the sound waves are not completely reflected back into the room at the bottom of the holding cassette, but can (partially) enter the cassette 12 through the holes 19.
[0178] However, FIG. 3 also illustrates that the holes 19 are at least partially covered by the heat-conducting plate 14 and thus “disabled”.
[0179] A heat-conducting plate (both conventional and according to the invention) typically has an outer contour formed by two indicated straight lines G1, G2, such that the region between the two straight lines G1, G2 would be completely acoustically disabled when using a conventional heat-conducting plate.
[0180] However, as shown in FIG. 3, the heat-conducting plate 14 according to the invention now offers the special feature of having a perforation 20 with perforations 21.
[0181] These perforations are essentially rectangular in the exemplary embodiment according to FIG. 3 (merely exemplary), and in particular as outwardly open edge recesses 21.
[0182] The perforations 21 thus all lie within (and recede behind) the enveloping contour of the heat-conducting plate 14 formed by the straight lines G1 and G2.
[0183] Providing perforations 21 on the heat-conducting plate 14 also creates (edge) tongues 22 on the heat-conducting plate.
[0184] FIG. 3 now illustrates that although the acoustic perforation 18 is essentially disabled in the region of the tongues 22, it can remain enabled in the region of the perforations 21 located therebetween.
[0185] In this way, the acoustic properties of a heat exchanger 10 are significantly improved compared to a heat exchanger with a conventional heat-conducting plate design, without this being accompanied by a noticeable drop in the heat conduction properties, in particular as the tongues 22 ensure sufficient heat transfer from the pipe section 13 to the inside 17 of the cassette 12 (or to the carrier plate 11 in a configuration according to FIG. 1).
[0186] As FIG. 3 further illustrates, the perforations 21 (as well as the tongues 22) are essentially (in particular completely) associated with side sections 23 and 24 of the heat-conducting plate 14, while the central section 25 is essentially (in particular continuously) designed without perforations.
[0187] However, the central section 25 is not flat, but has a bead 26 for receiving the pipe system or the pipe section 13.
[0188] Finally, it should be noted with regard to FIG. 3 that if a carrier plate 11 as shown in FIG. 1 were to be provided in this embodiment, this would typically also have an acoustic perforation, which could in particular be arranged (partially) congruently with the acoustic perforation 18 of the holding cassette 12.
[0189] Thus, the perforation 20 of the heat-conducting plate can also be described as an acoustic perforation.
[0190] Purely for reasons of better understanding, the present application refers to an acoustic perforation on the one hand (in relation to the holding cassette 12 or the carrier plate 11) and to a perforation 20 on the other hand in relation to the heat-conducting plate. However, this is not to say that these terms describe different hole shapes. Rather, instead of the rectangular edge recesses shown, the perforation could be formed completely in line with the acoustic perforation 18 of the holding cassette. Thus, no forms of holes or perforations are to be excluded from the invention.
[0191] The sequence of figures in FIGS. 4 to 8 is then intended to illustrate the manufacture of a heat-conducting plate 14 according to the invention or of a unit comprising a heat-conducting plate 14 and a pipe section 13:
[0192] FIG. 4 shows a highly schematic, planar view of a blank 27 in the form of a sheet metal plate. This sheet metal plate is preferably made of aluminum, in particular hard aluminum (in contrast to soft aluminum, which is often used for prior art heat-conducting plates).
[0193] In a first step, the basic shape of the heat-conducting plate 14 shown in FIG. 5a is worked out of this blank 27 by nibbling or punching the perforations 21 out of the blank 27, in particular with the aid of a nibbling machine. This creates the edge tongues 22 shown again in FIG. 5a.
[0194] The cross-sectional view according to FIG. 5b shows that the heat-conducting plate is still flat in this state. In this respect, the blank according to FIG. 4 also has an identical cross-section according to FIG. 5b.
[0195] In addition, it should be noted with regard to FIGS. 4 and 5 that a blank 27 with an enveloping contour corresponding to the enveloping contour of the intermediate product according to FIG. 5a is provided here only for reasons of clarity in FIG. 4. In fact, the particular configuration of the tongues 22, which can in particular have the same width b1 as the perforations 21, which have an identical width b2 (i.e. where b1=b2), makes it possible to have so-called “cutless punching” or “cutless nibbling”. In this way, several intermediate products as shown in FIG. 5a can be machined out of a large (not shown) sheet metal plate without any substantial waste, i.e. essentially no residual material, as what is removed to form a perforation 21 in the first intermediate product can provide a tongue 22 of an adjacent intermediate product machined out of the same sheet metal plate.
[0196] Thus, the same width of tongue and perforation enables (essentially) waste-free working.
[0197] Alternatively to the design of the perforations 21 shown in FIG. 5a, it is of course also possible to provide completely different types of perforations in the sheet metal plate 27; for example, perforations such as those shown in FIG. 3 for the holding cassette marked 19 or other perforations. In this sense, FIG. 9 shows perforations 21′ machined out of the sheet metal plate 27, which can also be described as edge recesses, as they are only provided in the side sections 23 and 24 of the blank (and not in the central section 25). However, these are not edge recesses open to the outside, but rather recesses in the edge region. FIG. 9 is only intended to illustrate that the perforations 21, 21′ do not have to be open to the outside, but can alternatively be completely surrounded by the sheet metal material.
[0198] All of the embodiments in FIGS. 1 to 8 can of course also be achieved with perforations 21′ as shown in FIG. 9 (or others) and shall be deemed disclosed in connection therewith.
[0199] Referring back to FIG. 5a, it should also be noted that the perforations 21 are obviously not evenly distributed over the entire surface 30 of the heat-conducting plate 14 or the blank, but are arranged, for example, only in the edge region, i.e. in the region of the side sections 23 and 24. Thus, it also results in particular that the side sections 23, 24 have more perforations (seven each in the exemplary embodiment according to FIG. 5a) than the central section 25 (no perforations).
[0200] FIG. 6a shows the result of a next method step, in a view according to FIG. 5a, wherein the intermediate product now differs in that a bead 26 has been worked, in particular embossed, into the central section 25.
[0201] This is illustrated in the cross-sectional view according to FIG. 6b.
[0202] The cross-sectional view according to FIG. 6c then shows an alternative, optional design of the heat-conducting plate, which, for the sake of simplicity, is designated 14′. This is where another optional processing step takes place; thus, the two side sections 23, 24 are brought or formed out of the sheet metal plane, downwards with respect to the open bead 26.
[0203] This shaping of the side sections 23, 24 causes them to be at an incidence angle α to one another (in the exemplary embodiment according to FIG. 6b, however, they lie together in the sheet metal plane B, so that no incidence angle arises).
[0204] In other words, the side sections 23, 24 form an angle β between them that is smaller than 180° (in the version according to FIG. 6b, however, the angle β is exactly) 180°.
[0205] This optional design with the set side sections 23 and 24 causes a certain bias of the heat conducting plate 14′ against the holding surface during subsequent attachment to a holding surface, as shown in FIGS. 1 and 3, which can lead to particularly good heat transfer, if necessary, as the tongues 22 or the side sections 23, 24 in particular rest securely against the holding surface.
[0206] Even though the heat-conducting plates in FIGS. 1 and 3 are mostly designated with the reference numeral 14 (and not 14′), the drawings should be understood as optionally showing heat-conducting plates 14′, in particular as it is not possible to tell from the drawing alone whether it is a matter of a heat-conducting plate 14 or 14′ (this also applies to the view of FIG. 6a and the following FIGS. 7a and 8a).
[0207] Here, FIG. 7a shows that in a next method step, a pipe section 13 can be introduced or inserted into the region of the bead 26 of the heat-conducting plate 14. Depending on the embodiment, the pipe section 13 may optionally be clipable into the bead 26 in such a way that it is held (non-detachably) in the heat-conducting plate 14 by the clipping process. Alternatively, the pipe section may merely be loosely inserted into the bead 26, depending on the embodiment. Insertion is also to be disclosed as shown in FIGS. 7b and 7c for both heat-conducting plate configurations 14 and 14′.
[0208] In a final method step according to FIG. 8a, holding means can now be attached to the heat-conducting plate 14. In the bottom view according to FIG. 8a, a double-sided adhesive tape 28 has been stuck to the central section 25 of the heat-conducting plate 14 as an example. Ideally, but not necessarily, the adhesive tape 28 is arranged in such a way that it does not cover either the perforations 21 or the tongues 22. However, in the exemplary embodiment, the adhesive tape 28 extends exactly to the beginning of the perforation 21 or tongues 22 and thus covers the entire central section 25, i.e. the section over the width B of which no perforations are arranged.
[0209] FIGS. 8b and 8c also show this tape arrangement for both configurations 14, 14′ of the heat-conducting plate.
[0210] In order to now move from a configuration according to FIG. 8a to an arrangement according to FIG. 1 or 3, the unit shown in FIG. 8a can be stuck into a holding cassette 12 or stuck onto a carrier plate 11, for example, while still at the production site.
[0211] Alternatively, the unit can first be transported to a (remote) assembly location as shown in FIG. 8a, to which, for example, the cassette 12 is also delivered. This means that the product can then be stuck in place at the assembly location as shown in FIG. 8a.
[0212] Further alternatively, a carrier plate 11 with a heat transfer plate and pipe system configuration arranged thereon may be brought to the assembly location to be stuck into the holding cassette.
[0213] To attach the heat-conducting plate 14 according to FIG. 8a to a corresponding holding surface, a protective layer of the double-sided adhesive tape 28 visible in FIG. 8a can be peeled off. For this purpose, a user can, for example, pull a corner 29 of this protective layer and peel it off.
[0214] For the sake of completeness, it should be noted that in the present application the heat-conducting plate 14 is referred to as a heat-conducting plate partly with and partly without holding means (here double-sided adhesive tape 28). The holding means can therefore belong to the heat-conducting plate. Typically, however, the pipe system 13 does not belong to the heat-conducting plate. However, as this is covered in particular by the double-sided adhesive tape 28 or the holding means, if applicable, a structural unit is created, which justifies the above explanations.
[0215] Finally, with regard to FIGS. 8a-c, it should be noted that these represent only one way of applying an adhesive to the heat-conducting plate 14, 14′ or the pipe section 13. Instead, an adhesive bead made of a viscous (to liquid) adhesive material could also be applied at the same, similar or comparable points (not shown), which would have the advantage in particular that this adhesive could fill cavities (provided with the reference numeral 31 in FIGS. 8b and 8c) between the heat-conducting plate 14, 14′ and the pipe section 13, which would lead to an improvement in the thermal conductivity of the entire heat exchanger.
[0216] In addition, the use of such an adhesive bead or a viscous (to liquid) adhesive would have the advantage that it can enter any (acoustic) fleece that may be present on the holding surface. In this way, on the one hand, thermal conduction properties of the fleece (at an acoustically inactive location anyway) can be improved and/or the attachment of the fleece to the holding surface can be improved (namely by the additional bonding of the adhesive passing through the fleece).
[0217] FIG. 10 then shows a section of the most preferred embodiment of a heat-conducting plate 14a according to the invention in a highly schematic oblique view.
[0218] This exemplary embodiment corresponds predominantly to the exemplary embodiment according to FIGS. 3 to 8, i.e. it also has a central section 25 with a bead 26 and also, in the region of the side sections 23 and 24, perforations 21, which on the one hand have or form tongues 22 next to them and on the other hand are designed as edge recesses open to the outside.
[0219] The big difference between the heat-conducting plate 14a and the heat-conducting plates according to FIGS. 1 to 8 is the way in which the perforations 21 are formed here in the manner of open edge recesses.
[0220] Thus, FIG. 10 shows that a non-cutting manufacturing method is used in which the perforations 21 are not simply punched out by removing material. Rather, the sheet metal plate is cut laterally to produce them and the resulting intermediate tongues 32 (which have the contour of the perforations 21) are then raised (at an angle), for example bent, folded or similar.
[0221] Such a design results in an improvement of the heat exchanger behavior, in particular if it is a system to which air is supplied above the sheet metal plane.
[0222] FIG. 11a then shows a bottom view of the complete heat-conducting plate 14a showing the pipe section 13 (whereas FIG. 10 shows only one section, in particular according to a width extension marked X in FIG. 11a).
[0223] The bottom view according to FIG. 11a also shows the alternating arrangement of tongues 22 and (raised) intermediate tongues 32. By raising the tongues 32 (i.e. with respect to FIG. 11a, towards the other side of the plane of the figure, away from the viewer), perforations 21 are created in the manner of lateral edge recesses as shown in FIGS. 1 to 8 (which, of course, are not as clearly visible in FIG. 11a as in FIG. 10, for example, due to the view).
[0224] In the exemplary embodiment according to FIG. 11a, tongues and (raised) intermediate tongues alternate continuously. They extend along the entire longitudinal extension of the heat-conducting plate 14a.
[0225] FIG. 11b then shows a kind of sectional view, although it is probably more of a frontal view, roughly according to view arrow XIb in FIG. 11a. Thus, FIG. 11b shows particularly well that between the tongue 22a and the raised intermediate tongue 32a (which of course would not be visible in a pure sectional view), at least in the side view, there is an elevation angle γ. This elevation angle γ is in particular between 1° and 180°, in the present case about 20° as an example.
[0226] FIG. 11b shows that the heat-conducting plate 14a is essentially axially symmetrical, i.e. that a pair of tongues 22 and (raised) intermediate tongues 32 always alternate in the axial direction of the heat-conducting plate 14a.
[0227] The intermediate tongues 32 of a pair thus preferably have an (axially symmetrically mirrored) identical elevation angle γ.
[0228] FIG. 11c then shows that in this exemplary embodiment, too, the heat-conducting plate 14a′, analogous to the exemplary embodiments according to FIG. 6c or 7c of the heat-conducting plate 14a′, can have inclined side sections 23, 24 or tongues 22, which can cause a certain pre-tensioning of the heat-conducting plate 14a′ against the holding surface when it is later attached to a holding surface, which can lead to particularly good heat transfer, as a secure and snug attachment of the tongues 22a′ to the holding surface is made possible.
[0229] Finally, it should be pointed out that in FIGS. 11b and 11c the main extension plane E of the heat-conducting plate is indicated by dashed lines, which is therefore the sheet metal plane from which the heat-conducting plate is typically machined in its blank holder.
[0230] Such a holding surface 11 is then shown again as an example in FIG. 12, in which the tongues 22 can either not be pre-tensioned according to FIG. 11b or can be pre-tensioned according to FIG. 11c (this is typically no longer distinguishable in the later assembly state).
[0231] The difference between FIG. 12 and FIG. 11 is essentially that FIG. 11 is intended to illustrate that a substantially larger incidence angle γ of more than 45°, in particular of more than 70°, for example of between 70° and 100° (in the present case of approximately 80° by way of example) can also be selected, wherein such an embodiment is even preferred by the applicant, at least at the time of filing of the present patent application, since corresponding thermal tests were particularly promising.
