LOW-FLUX CAB SOLDERING FOR HEAT EXCHANGERS

Description

[0001] The present invention relates to a semi-finished product for semi-finished components for producing a heat exchanger, a heat exchanger assembly prepared for subsequent CAB brazing from semi-finished components, a brazing process for producing heat exchangers from semi-finished components and a heat exchanger produced using a CAB brazing process.

[0002] Currently, there is an increasing search for ways to solder aluminum heat exchangers without wetting agents or fluxes, such as potassium aluminum tetrafluoride, Nocolok or the like, in a process-safe manner, since the wetting agent can cause problems when used subsequently as intended.

[0003] One possible variant of flux-free soldering is the VAC soldering process, in which the heat exchanger is soldered in a vacuum. In this process, magnesium is usually added to the core material and, if applicable, to the coatings applied to the core material. This is to facilitate the breaking up of the oxide layer on the surface and, due to the gettering effect, to remove any remaining free residual oxygen from the immediate vicinity of the material surface. The magnesium escaping from the material reacts with the oxygen molecules near the surface, resulting in a partial depletion of oxygen in the residual vacuum, at least in the area of the material surfaces. This reduces or prevents reoxidation or increased oxidation of the material surface, and the surface exhibits sufficiently good soldering behavior of the solder layer on the surfaces.However, the disadvantage of the VAC brazing process is that it is usually designed as a batch process, so that continuous production of the heat exchangers can only be achieved with a high level of design effort.

[0004] In contrast to the VAC brazing process, the CAB brazing process – another manufacturing process for aluminum heat exchangers – can be continuous because it can work with a protective gas atmosphere instead of a vacuum. Low-oxygen nitrogen gas, for example, can be used as a protective gas, which is used to flood the brazing device, which may be continuously constructed. However, in the CAB brazing process, it is common practice to use fluxes such as potassium aluminum fluoride to improve the wettability of the surfaces. However, during subsequent intended use of the heat exchangers, these fluxes can tend to degrade the fluid flowing through the fluid channels, causing precipitation. The associated disadvantages can have a negative impact on the performance of the heat exchanger. In extreme cases, this gel formation can even lead to partial blockage of the fluid channels.As a result, there is an increasing search for ways to replace such fluxes or to do without them altogether.

[0005] EP 1637 267 A1 discloses a method for brazing aluminum components, which is designed as a CAB brazing process and does not require the use of flux. This is achieved, among other things, by adding magnesium to the core material of the semi-finished product used. Due to the magnesium present in the core material, which diffuses into the solder layer during the brazing process, the oxide layer on the material surface can be broken up during the brazing process, thereby improving the wettability of the solder layer during the brazing process. In addition, the core material is usually coated with a solder layer with a lower magnesium content. This can prevent an oxide layer from forming beforehand on the material surface. This oxide layer has a high magnesium oxide content and is therefore less easily broken up by magnesium.During the soldering process, the magnesium present in the core material diffuses through the solder layer, ensuring sufficient wetting of the solder layer on the surfaces. Due to the appropriate design of the soldering equipment, it is also possible to create a protective gas atmosphere with less than 20 ppm oxygen. Such a low oxygen content in the protective gas atmosphere also allows for sufficiently good soldering of the components without the use of flux, partly due to a low reoxidation rate caused by the significantly reduced oxygen content. However, since this process requires at least two soldering chambers, it is structurally complex and cost-intensive.

[0006] EP 3 445 530 A1 discloses an aluminum composite material comprising a core layer made of an AL3000 alloy and a corrosion protection layer made of an AL7000 alloy. Furthermore, the aluminum composite material is coated on both sides with a brazing layer made of an AL4000 alloy.

[0007] In one aspect of the invention, a semi-finished product for semi-finished components for producing a heat exchanger, in particular according to a CAB brazing process, is proposed, made of a core material and at least on one side with a brazing layer and a corrosion-reducing intermediate layer arranged between the brazing layer and the core material, wherein the core material consists of an AI3000 alloy or an AI6000 alloy which has 0.1% to 1.5% magnesium, wherein the brazing layer consists of an AI4000 alloy which has a maximum of 0.2% magnesium, wherein the corrosion-reducing intermediate layer consists of an Al1000 alloy or an AI7000 alloy which has 0.2% to 0.4% magnesium.

[0008] Advantageously, semi-finished components can be produced from such a semi-finished product, which can be brazed to a heat exchanger using a CAB brazing process, possibly continuously. This is achieved by ensuring that the corrosion-reducing intermediate layer has the same or at least a similar magnesium content as the core material, so that the magnesium can diffuse to the brazing layer or the surface of the brazing layer through activation due to the thermal energy during the heating process, without being trapped by the corrosion-reducing intermediate layer due to an insufficient magnesium content. Consequently, the use of such a semi-finished product can advantageously improve the corrosion properties in the finished heat exchanger, and a CAB brazing process can be applied without the use of flux.

[0009] A semi-finished product is a metal sheet or aluminum sheet, possibly wound on a reel, from which semi-finished components can be manufactured. The semi-finished product can consist of a core material and be coated with a brazing layer on at least one side. This brazing layer can be applied to the core material, for example, by plating. It is also conceivable for the semi-finished product to have a corrosion-reducing intermediate layer on at least one side, arranged between the brazing layer and the core material. Such a corrosion-reducing intermediate layer can also be applied to the core material by plating.

[0010] Semi-finished components are components that are manufactured from a semi-finished product by punching, stamping, forming, or similar processes. Such semi-finished components can be designed as shells or half-shells that are arranged and brazed together to form a heat exchanger. The term "semi-finished components" also includes flange plates, end plates, end plates, base plates, fins, turbulence inserts, and the like.

[0011] In this context, "sided," "one-sided," "double-sided," or "side" of a semi-finished product or semi-finished component refers to the top or bottom of the flat semi-finished product, or the top and bottom of the semi-finished component. Accordingly, a distinction is made between the top, bottom, and the edges and peripheral areas of the semi-finished product or semi-finished component.

[0012] If the semi-finished components are assembled into a heat exchanger assembly, a heat exchanger assembly prepared in this way can be formed into a heat exchanger by brazing. A heat exchanger assembly is thus understood to be a number of semi-finished components arranged relative to one another and, if necessary, fixed to one another, which, when prepared in this way, form a heat exchanger through subsequent brazing.

[0013] The core material of a semi-finished product is the centrally located layer of the semi-finished product, which is usually the thickest. The brazing layer is the surface layer of the semi-finished product, which has brazing properties and is used to braze the semi-finished components together to form the heat exchanger.

[0014] A corrosion-reducing intermediate layer is a layer that imparts improved corrosion resistance to the material assembly consisting of the core and, if applicable, the solder layer, compared to a core material without an intermediate layer and / or the solder layer. Corrosion reduction can be achieved by making the corrosion-reducing intermediate layer less noble than, for example, the core material due to its chemical composition. In this case, it is possible that, during a corrosive attack, the corrosion-reducing intermediate layer will sacrifice itself to the core material, thus exerting its corrosion-reducing effect. It can be arranged between the solder layer and the core material or, as the top layer, at least on one side of the semi-finished product.If the corrosion-reducing intermediate layer is the topmost layer of the semi-finished product, the solder material for soldering the semi-finished components may necessarily be provided by another component or by solder pastes or other applied solder material. Since the semi-finished components are ultimately made from the semi-finished product, the semi-finished components are also constructed analogously to the semi-finished product in terms of their layer structure.

[0015] A CAB soldering process is a soldering process using a controlled protective gas atmosphere which has such a low oxygen content that reoxidation of the cracked aluminum surfaces during soldering is reduced to such an extent that a sufficiently good soldering of the semi-finished components is possible.

[0016] The above or following concentration information of components in % are to be understood in particular as % by weight.

[0017] It is also conceivable that the core material contains 0.1% to 1.25% magnesium, for example 0.1% to 1.0% magnesium, in particular 0.1% to 0.6% magnesium and possibly 0.2% to 0.4% magnesium.

[0018] It is also conceivable that the solder layer contains a maximum of 0.15% magnesium, for example a maximum of 0.1% magnesium, in particular a maximum of 0.08% magnesium and possibly a maximum of 0.05% magnesium.

[0019] Furthermore, it is conceivable that the corrosion-reducing intermediate layer contains 0.2% to 0.4% magnesium.

[0020] Furthermore, the core material can contain 0.0% to 0.9% silicon, for example 0.0% to 0.8% silicon, possibly 0.0% to 0.7% silicon and for example 0.0% to 0.6% silicon.

[0021] The above-mentioned concentrations of silicon advantageously lead to precipitations in the edge zones during the Si diffusion from the solder into the core material, which forms an electrochemically protective layer.

[0022] Furthermore, the core material can contain 0.0% to 0.6% iron, in particular 0.0% to 0.5% iron, possibly 0.0% to 0.4% iron and, for example, 0.0% to 0.3% iron.

[0023] Iron advantageously forms precipitates with manganese and / or silicon, which support the formation of an electrochemical, particularly electrochemically protective, layer.

[0024] Furthermore, the core material can contain 0.0% to 1.25% copper, 0.0% to 1.2% copper, in particular 0.0% to 1.0% copper and, for example, 0.0% to 0.7% copper.

[0025] Copper advantageously increases the electrochemical free potential, so that corrosion attack is limited to the electrochemically less noble areas, whereby any corrosion that may occur can be kept away from the core material as far as possible.

[0026] Furthermore, the core material can contain 0.6% to 1.9% manganese, in particular 0.7% to 1.6% manganese, possibly 0.8% to 1.5% manganese and, for example, 0.9% to 1.4% manganese.

[0027] Manganese advantageously increases the strength of the respective material and forms precipitates with, for example, silicon in the layers touched by an incoming Si diffusion, whereby the precipitates in the above-mentioned layers lower the electrochemical potential and consequently act as superficial sacrificial layers, so that the core material can be protected as far as possible from corrosion.

[0028] Furthermore, the solder layer can contain 6.5% to 125% silicon, for example 6.5% to 12% silicon, in particular 6.5% to 11% silicon and for example 6.5% to 10.5% silicon.

[0029] Aluminum and silicon advantageously form a eutectic at 577°C, so that by adding an above-mentioned amount of silicon to an aluminum alloy, a solder can be formed that at least partially melts during soldering and solders the components together.

[0030] Furthermore, the solder layer can contain 0.2% to 2.5% zinc, in particular 0.3% to 2.5% zinc, for example 0.4% to 2.0% zinc and possibly 0.5% to 1.0% zinc.

[0031] Furthermore, the corrosion-reducing intermediate layer can contain 0.2% to 2.5% zinc, in particular 0.3% to 2.5% zinc, possibly 0.4% to 2.0% zinc and, for example, 0.5% to 1.0% zinc.

[0032] Zinc advantageously lowers the electrochemical free potential of the respective material, so that the layer formed from the material can serve as a sacrificial layer against more noble areas, in particular the core material.

[0033] If the corrosion-reducing intermediate layer has a thickness of 10 to 200 µm, a significant improvement in the corrosion behavior of the finished heat exchanger can be achieved with only a small amount of material, since such a thickness provides sufficient corrosion protection against the aggressive media that usually flow in the fluid channels.

[0034] Furthermore, the corrosion-reducing intermediate layer can have a thickness of 15 to 175 µm, in particular of 20 to 150 µm, possibly of 25 to 100 µm and, for example, of 30 to 75 µm.

[0035] If the semi-finished product has a material sequence of core material-corrosion-reducing intermediate layer-brazing layer, a CAB brazing process with at least reduced flux usage can advantageously be carried out at least on one side, wherein the corrosion properties of the heat exchanger are improved at least in the fluid channels with such a corrosion-reducing intermediate layer due to the corrosion-reducing intermediate layer used.

[0036] If the material sequence is brazing layer-core material-corrosion-reducing intermediate layer-brazing layer, a low-flux or flux-free CAB brazing process can be applied on both sides, whereby an improvement in the corrosion properties of the heat exchanger in the associated fluid channels is possible at least on one side due to the use of the corrosion-reducing intermediate layer.

[0037] If a material sequence of brazing layer-corrosion-reducing intermediate layer-core material-corrosion-reducing intermediate layer-brazing layer is used, a flux-free CAB brazing process can advantageously be applied on both sides with such a semi-finished product, whereby the corrosion resistance of the heat exchanger in the associated fluid channels can be improved due to the use of the corrosion-reducing intermediate layer on both sides.

[0038] In a further aspect of the invention, a heat exchanger assembly prepared for subsequent CAB brazing is proposed, consisting of semi-finished components, wherein at least some semi-finished components have a core material made of an AL3000 alloy or an AL6000 alloy, which comprises 0.1% to 1.5% magnesium and has on one or both sides a brazing layer made of an AL4000 alloy, which comprises a maximum of 0.2% magnesium.

[0039] When using such a prepared heat exchanger assembly, CAB soldering can be advantageously carried out, since the magnesium can break up the oxide layers on the surfaces and, at least close to the surface, the microscopic protective gas atmosphere can have a reduced or even no free oxygen content due to the gettering effect.

[0040] It is also conceivable that the core material contains 0.1% to 1.25% magnesium, for example 0.1% to 1.0% magnesium, in particular 0.1% to 0.6% magnesium and possibly 0.2% to 0.4% magnesium.

[0041] It is also conceivable that the solder layer contains a maximum of 0.15% magnesium, for example a maximum of 0.1% magnesium, in particular a maximum of 0.08% magnesium and possibly a maximum of 0.05% magnesium.

[0042] In a further aspect of the invention, a heat exchanger assembly prepared for subsequent CAB brazing is proposed, wherein at least some semi-finished components are made from a semi-finished product as described above and consequently have, at least on one side, a corrosion-reducing intermediate layer made of an AL1000 alloy or an AL7000 alloy comprising 0.2% to 0.4% magnesium arranged between the brazing layer and the core material.

[0043] Advantageously, the use of such a heat exchanger assembly allows for the use of a CAB brazing process, eliminating the need for fluxes. Furthermore, due to the corrosion-reducing intermediate layer, the heat exchanger manufactured from the heat exchanger assembly is designed to be corrosion-resistant, at least in certain sections, at least in predetermined fluid channels, thus improving the overall corrosion properties of the heat exchanger.

[0044] Furthermore, it is conceivable that the corrosion-reducing intermediate layer contains 0.2% to 0.4% magnesium.

[0045] Furthermore, the solder layer can be arranged in a future gas-carrying fluid channel on the semi-finished component.

[0046] This advantageously allows CAB brazing to be performed in the gas-carrying fluid channel. This is achieved, among other things, because the future gas-carrying fluid channels are usually preformed in the prepared heat exchanger assembly and are essentially only exposed to a limited extent to the surrounding protective gas atmosphere during the brazing process. Consequently, a microscopic protective gas atmosphere can form in the future gas-carrying fluid channels, which may have a reduced oxygen content compared to the macroscopic protective gas atmosphere prevailing in the brazing device. This allows the free oxygen content in the area of the surfaces to be brazed to such an extent that low-flux or flux-free CAB brazing is possible.

[0047] Furthermore, a solder layer can be arranged in a future liquid-carrying fluid channel.

[0048] Since even a small amount of flow through the surrounding shielding gas atmosphere is not expected, especially in the case of a future fluid-carrying fluid channel, disruptive exchange of the atmosphere directly at the contact surfaces or surfaces to be soldered is minimal or nonexistent. Thus, the oxygen reduction resulting from the gettering effect caused by the inflow of shielding gas, which contains unavoidable residual oxygen, is not impaired or only slightly impaired during the soldering process. This means that, especially with future fluid-carrying fluid channels, the use of flux during the CAB soldering process can be dispensed with.

[0049] Furthermore, the corrosion-reducing intermediate layer can be arranged in a future gas-carrying fluid channel. In this case, the corrosion resistance in the gas-carrying fluid channel in the heat exchanger manufactured from the heat exchanger assembly can be advantageously improved.

[0050] Furthermore, the corrosion-reducing intermediate layer can be arranged in a future fluid-carrying fluid channel. This can also advantageously improve the corrosion properties of the fluid-carrying fluid channels in the final assembled heat exchanger.

[0051] In this context, a future gas-carrying fluid channel or a future liquid-carrying fluid channel is understood to mean the areas or channels of the heat exchanger assemblies which, after soldering the heat exchanger assembly to the heat exchanger, form a respective gas-carrying fluid channel or liquid-carrying fluid channel.

[0052] In a further aspect of the invention, a soldering method for producing heat exchangers from semi-finished components is proposed, in which a heat exchanger assembly according to one of the preceding claims is soldered to a heat exchanger by means of a CAB soldering method.

[0053] When using such semi-finished components, a CAB soldering process can be advantageously used without the need for flux.

[0054] Furthermore, the macroscopic protective gas atmosphere in a soldering apparatus can have an oxygen content of 10 to 500 ppm.

[0055] Advantageously, the CAB brazing process can still be performed even when the oxygen content in the macroscopic shielding gas atmosphere is still relatively high, with or without the use of flux. Consequently, a more cost-effective shielding gas can be used and / or the expensive and time-consuming reduction of the oxygen content in the shielding gas atmosphere can be largely avoided, possibly through design measures such as the use of two or more soldering units.

[0056] It is also conceivable that the oxygen content of the macroscopic protective gas atmosphere has an oxygen content of 20 to 500 ppm, in particular of 50 to 500 ppm, possibly of 70 to 500 ppm and, for example, of 100 to 500 ppm.

[0057] In a further aspect of the invention, a heat exchanger is proposed, produced by a CAB brazing process, in particular as described above, using semi-finished components, in particular as described above, which are produced from semi-finished products, in particular as described above.

[0058] Advantageously, the CAB process allows the production of a flux-free or at least low-flux heat exchanger without the need for laborious removal of the flux after the heat exchanger has been manufactured. Thus, in a heat exchanger manufactured in this way, the adverse precipitations from the fluid used due to chemical interaction with flux residues are eliminated or reduced to a minimal extent.

[0059] Furthermore, the heat exchanger can be designed as a liquid-cooled charge air cooler.

[0060] In this case, it is advantageous to dispense with the use of flux, or to use it only to a reduced extent, at least in the area of the liquid-carrying fluid channels. This is because, in the case of a liquid-cooled charge air cooler, the liquid-carrying fluid channels are almost closed to the surrounding macroscopic protective gas atmosphere, even in the case of the prepared heat exchanger assembly. This means that a microscopic protective gas atmosphere in the area of the liquid-cooled fluid channels can have a lower oxygen content than the macroscopic protective gas atmosphere that prevails in the soldering equipment due to the gettering effect of the magnesium. Consequently, a protective gas atmosphere with a higher oxygen content can be used in liquid-cooled charge air coolers without the need for flux for soldering, since mixing of the protective gas atmosphere orthe flow through them in the future fluid-carrying fluid channels is negligible due to the design.

[0061] However, it is conceivable that even in a liquid-cooled intercooler, fluxing can be omitted in the gas-carrying fluid channels, since even in these gas-carrying fluid channels, penetration or mixing of the macroscopic protective gas atmosphere into the microscopic region of the gas-carrying fluid channels can be largely minimal even in the prepared heat exchanger assembly. In this respect, the gettering effect of magnesium on the microscopic protective gas atmosphere in the area of the solder joints can also have an oxygen-reducing effect in the gas-carrying fluid channels, without significantly counteracting the reduction in oxygen content at the microscopic level caused by the penetrating, residual oxygen-containing macroscopic protective gas atmosphere in the gas-carrying fluid channels.

[0062] Furthermore, the heat exchanger can be designed in a shell construction.

[0063] Particularly in the shell construction, fluid channels can be advantageously formed which are largely closed to the environment and in which an exchange of the microscopic protective gas atmosphere in the fluid channels with the macroscopic protective gas atmosphere in the soldering apparatus is largely excluded or reduced.

[0064] Furthermore, the heat exchanger can be designed in a plate construction.

[0065] Advantageously, with this design, fluid channels can be formed at least within the plates, the microscopic protective gas atmosphere of which is essentially not in constant exchange with a macroscopic protective gas atmosphere, so that in this case too, the gettering effect of the magnesium can lead to a reduction of the oxygen content in the microscopic protective gas atmosphere or in the area of the soldering area.

[0066] A macroscopic protective gas atmosphere is the composition of the protective gas in the soldering equipment, particularly in the area located between the heat exchangers and surrounding the heat exchangers or the heat exchanger assemblies prepared for soldering. A microscopic protective gas atmosphere is the composition of the protective gas in the area of the fluid channels or in the area of the components to be soldered or in the area of the solder joints. In special designs, the microscopic protective gas atmosphere in the area of the fluid channels is largely encapsulated compared to the macroscopic protective gas atmosphere, so that there is essentially no exchange of the microscopic protective gas atmosphere with the macroscopic protective gas atmosphere, or this exchange occurs only to a very small extent.

[0067] They show, schematically: Fig. 1 shows a heat exchanger in plate construction, Fig. 2 shows a heat exchanger in shell construction, Fig. 3 shows a semi-finished product wound on a roll, Fig. 4 shows a cross section through a semi-finished product in the installed position in a heat exchanger assembly prepared for subsequent soldering, Fig. 5 shows a schematic representation of the gettering effect occurring when using semi-finished products according to the invention.

[0068] A heat exchanger 100 in plate construction 110 comprises, as a prepared heat exchanger assembly 120, several half-shells 130, 130', which are each brazed together in pairs to form a plate pair 135. Between these paired half-shells 130, 130', i.e., within the plate pairs 135, a first fluid channel 140 is formed in each case, through which a first fluid flows in the fully assembled heat exchanger 100. The first fluid enters such first fluid channels 140 via domes 150, which are also formed from the half-shells 130, 130' by brazing.

[0069] An insert 160, in particular a turbulence insert 160, can be inserted into these first fluid channels 140.

[0070] Due to the stacked design, additional second fluid channels 170 are formed between the plate pairs 135 formed from the half-shells 130, 130', into which inserts 180, in particular in the form of fins, can also be inserted. Both the inserts 160 and the inserts 180 can be brazed to the half-shells 130, 130' and to the plate pairs 135, respectively, in the fully assembled heat exchanger 100. Furthermore, the heat exchanger 100 can have a final flange plate 190 or a final base plate 200.

[0071] In addition, connection pieces 210 can be arranged on the flange plate 190, by means of which the first fluid can be supplied to the first fluid channels 140 via the domes 150 or can be discharged from the first fluid channels.

[0072] The entire illustrated heat exchanger assembly 120 therefore comprises semi-finished components, which can be designed as half-shells 130, 130', inserts 160, plate pairs 135, inserts 160, 180, flange plates 190, base plates 200, and connecting pieces 210. It is also conceivable that other semi-finished components may be used.

[0073] A heat exchanger 100 designed in this plate construction 110 can be used, for example, as a liquid-cooled charge air cooler 220, wherein the first fluid is in the form of a liquid, for example, a cooling liquid comprising water and / or glycol and / or corrosion inhibitors. In this case, the cooling liquid is fed to the first liquid channels 140 via the connecting pieces 210 or is discharged from the first liquid channels 140. The second fluid, designed as charge air and which may at least partially contain exhaust gas, flows through the second fluid channels 170. In this case, a liquid-gas heat exchanger is present. However, it is also conceivable for the second fluid to also be in the form of a liquid, so that in this case a liquid-liquid heat exchanger is present.It is also possible for either the first fluid or the second fluid to be used as a two-phase fluid, which is at least partially converted from the gaseous state to the liquid state in the heat exchanger. In this case, the heat exchanger is designed as a condenser.

[0074] The heat exchanger 100 according to Fig. 2 is designed in a shell construction 230 and has a plurality of pipe shells 240, 240'. These pipe shells 240, 240' are hidden inside one another and, due to their concealment from one another, form first fluid channels 250 and second fluid channels 260. A first fluid flows through the first fluid channel 250 and a second fluid flows through the second fluid channel 260. Inserts can be positioned in the first fluid channels 250 and / or in the second fluid channels 260 and / or the pipe shells 240, 240' can be equipped with dimple-shaped bulges 270, which on the one hand serve to support the subsequent pipe shell 240, 240' and to increase the tensile strength, and which on the other hand can form microscopic fluid channels in the first fluid channels 250 and the second fluid channels 260.

[0075] Furthermore, the heat exchanger 100 can be equipped with an end-side flange plate 280, which is connected to a base tube shell 290, into which an insert 300 and a subsequent normal tube shell 240, 240' can be inserted. On the side opposite the flange plate 280, the heat exchanger 100 can be closed by an end tube shell 310, which is inserted into the last tube shell 240, 240' and / or by an end plate 320, which is arranged in the end tube shell 310 or in the last tube shell 240, 240'. An insert 330 can be arranged between the end tube shell 310 and the last normal tube shell 240, 240'.

[0076] The first fluid channels 250 and the second fluid channels 260 can be supplied with the respective fluid via domes 340 formed from the pipe shells 240, 240'.

[0077] Such a heat exchanger 100 can be designed as a liquid-cooled oil cooler 345, wherein, for example, the first fluid channels 250 are flowed through by the cooling liquid, comprising water and / or glycol and / or corrosion inhibitors, while the second fluid channels 260 are flowed through by the oil to be cooled. The first fluid and the second fluid can be supplied to and discharged from the first fluid channels 250 and the second fluid channels 260, respectively, via openings 350 formed in the flange plate 280 by means of the domes 340.

[0078] In the case of the Fig. 2 In the heat exchanger 100 shown, semi-finished components 360 can therefore be designed as pipe shells 240, 240', flange plates 280, base pipe shells 290, inserts 300, end pipe shells 310, end plates 320, inserts 330.

[0079] Such semi-finished components 360 can be made from a semi-finished product 370, as in Fig. 3 shown, can be manufactured. Such semi-finished products 370 can be wound on a roll 380 and used in the process, wherein the semi-finished product 370 has an upper side 390 and a lower side 400. Accordingly, in the case of a semi-finished product 370, a one-sided or two-sided design is to be understood as the design on the upper side 390 and / or on the lower side 400. In the case of the semi-finished components 360, the above terminology refers to the respective original upper side 390 and / or lower side 400 of the semi-finished product 370.

[0080] Such a semi-finished product 370 or such a semi-finished component 360, as in Fig. 4 As shown, in cross-section and in the installed position in the heat exchanger assembly 120, it can have a core material 410, which typically has the greatest thickness. A brazing layer 420 can be directly connected to the core material 410 on at least one side.

[0081] By means of such a solder layer 420, structures 430 of further semi-finished components 360, such as dimple-shaped bulges 270, inserts 180, which can be designed as lamellae, or inserts 160, 300, 330, which can be designed as turbulence inserts, can be soldered.

[0082] It is also conceivable that such a solder layer 420 is applied to both sides of the core material 410.

[0083] A corrosion-reducing intermediate layer 440 can be arranged adjacent to the core material 410 on at least one side, to which a solder layer 420 can in turn be connected. In this case, the solder layer 420 also achieves brazing of the structures 430 of other semi-finished components 360, wherein, after brazing, the corrosion-reducing intermediate layer 440 leads to an improvement in the corrosion resistance of the heat exchanger, at least in the adjacent fluid channel 140, 170, 250, 260.

[0084] In the case of prefabricated building 110, as in Fig. 1 As shown, it is conceivable that a corrosion-reducing intermediate layer 440 is provided only in the second fluid channel 170, while only the solder layer 420 is found in the first fluid channel 140 in the heat exchanger assembly 120. Accordingly, a corrosion-reducing intermediate layer 440 is used only in the gas-carrying fluid channel and thus in the second fluid channel 170. However, it is also conceivable that a corrosion-reducing intermediate layer 440 is provided in both fluid channels 140, 170.

[0085] In the case of the shell construction 230, as in Fig. 2 As shown, a corrosion-reducing intermediate layer 440 may be provided in the first fluid channel 250 and / or in the second fluid channel 260 or in none of the fluid channels 250, 260.

[0086] In a CAB soldering process 450, as in Fig. 5As shown, with increasing heating 470, the magnesium 460 contained in the core material 410 diffuses from the center of the core material 410 to the surface 480 and accumulates there, breaking up the surface oxide layer on the one hand and at least partially transitioning into the gas phase on the other. The oxygen molecules 490 contained in the fluid channels 140, 170, 250, 260 can then react with the magnesium 460 near the surface to form magnesium oxide 500 and thus reduce the free residual oxygen content in the microscopic protective atmosphere region 510 at least close to the surface 480 and, if applicable, in the microscopic protective atmosphere region 510 adjacent thereto.Because the fluid channels 140, 170, 250, 260 are essentially fluidically separated from the macroscopic protective gas atmosphere 520 surrounding the heat exchanger assembly 120, it is possible to permanently reduce the free residual oxygen content, at least within the microscopic protective gas atmosphere 510, during the soldering process without the oxygen reduction being impaired by oxygen penetrating from the macroscopic protective atmosphere 520. Consequently, and particularly in the case of a plate construction 110 or a shell construction 230, a heat exchanger assembly can be soldered without the use of fluxes using a CAB soldering process 450.

Claims

1. A semi-finished product for semi-finished components (360) for manufacturing a heat exchanger (100), in particular according to a CAB soldering process (450), from a core material (410) and at least on one side with a solder layer (420) and a corrosion-reducing intermediate layer (440), disposed between the solder layer (420) and the core material (410), wherein the core material (410) consists of an Al3000 alloy or an Al6000 alloy, which has 0.1% to 1.5% Mg, wherein the solder layer (420) consists of an Al4000 alloy, which has a maximum of 0.2% Mg, wherein the corrosion-reducing intermediate layer (440) consists of an Al1000 alloy or an Al7000 alloy, which has 0.1% to 1.5% Mg.

2. The semi-finished product according to any one of the preceding claims, wherein the core material (410) has at least a concentration of an element, selected from the following group: 0.0% to 1.0% Si, 0.0% to 0.7% Fe, 0.0% to 1.5% Cu, 0.5% - 2.0% Mn.

3. The semi-finished product according to any one of the preceding claims, wherein the solder layer (420) has at least a concentration of an element, selected from the following group: 6.5% to 13% Si, 0.2% to 5% Zn.

4. The semi-finished product according to any one of the preceding claims, wherein the corrosion-reducing intermediate layer (440) has at least a concentration of an element, selected from the following group: 0.2% to 5% Zn.

5. The semi-finished product according to any one of the preceding claims, wherein the corrosion-reducing intermediate layer (440) has a thickness of 10-200 µm.

6. The semi-finished product according to any one of the preceding claims, wherein the semi-finished product (370) has at least a material sequence, selected from the following group: core material (410)-corrosion-reducing intermediate layer (440)-solder layer (420), solder layer (420)-core material (410)-corrosion-reducing intermediate layer (440)-solder layer (420), solder layer (420)-corrosion-reducing intermediate layer (440)-core material (410)-corrosion-reducing intermediate layer (440)-solder layer (420).

7. A heat exchanger assembly (120), prepared for subsequent CAB soldering, from semi-finished components (360), wherein at least some semi-finished components (360) have a core material (410) from an Al3000 alloy or an Al6000 alloy, which comprises 0.1% to 1.5% Mg and has, on one or both sides, a solder layer (420) from an AL4000 alloy, which comprises max. 0.2% Mg, wherein at least some semi-finished components (360) are manufactured from a semi-finished product (370) according to any one of the preceding claims and consequently have, at least on one side, a corrosion-reducing intermediate layer (440) from an Al1000 alloy or Al7000 alloy, which comprises 0.2% to 0.4% Mg, arranged between the solder layer (420) and the core material (410).

8. The heat exchanger assembly according to any one of the preceding claims from semi-finished components (360), wherein at least some semi-finished components (360) have a core material (410) from an Al3000 alloy or an Al6000 alloy, which comprise at least an element in a specified concentration, selected from the following group: 0.0% to 1.0% Si, 0.0% to 0.7% Fe, 0.0% to 1.5% Cu, 0.5% - 2.0% Mn and has, on one or both sides, a solder layer (420) from an AL4000 alloy, which comprises 6.5% to 13% Si.

9. The heat exchanger assembly according to any one of the preceding claims, wherein at least one of the layers (420,440) has an arrangement, selected from the following group: an arrangement of the solder layer (420) in a future gas-carrying fluid channel, an arrangement of the solder layer (420) in a future liquid-carrying fluid channel, an arrangement of the corrosion-reducing intermediate layer (440) in a future gas-carrying fluid channel, an arrangement of the corrosion-reducing intermediate layer (440) in a future liquid-carrying fluid channel.

10. A soldering method for manufacturing heat exchangers (100) from semi-finished components (360), wherein a heat exchanger assembly (120) according to any one of the preceding claims is soldered to a heat exchanger (100) by means of a CAB soldering method (450).

11. The soldering method according to any one of the preceding claims, wherein the macroscopic protective gas atmosphere (520) in a soldering device has an oxygen content of max. 10-500 ppm.

12. A heat exchanger, manufactured with a CAB soldering process (450), in particular according to any one of the preceding claims, using semi-finished components (360), in particular according to any one of the preceding claims, which are manufactured from semi-finished product (370), in particular according to any one of the preceding claims.

13. The heat exchanger according to any one of the preceding claims, wherein the heat exchanger (100) has at least a configuration, selected from the following group: a configuration as a liquid-cooled intercooler (220), a configuration as a liquid-cooled oil cooler (), a configuration as shell structure (230), a configuration as panel structure (110).