Heat exchanger, method for manufacturing same, aluminum alloy plate for flow path formation, tube material for heat exchanger, and flow path outer wall material for heat exchanger

Abstract

A heat exchanger (1) is provided with: a plurality of flow path formation parts (2) which are each provided with a first flow path (11), and are arranged at intervals from each other; and a second flow path (12) which is formed between the flow path formation parts (2). Each of the flow path formation parts (2) has: a first outer wall part (21) that constitutes a portion of the outer wall of the first flow path (11) that faces one second flow path (12a) of the two second flow paths (12) that are adjacent to the flow path formation part (2); a second outer wall part (22) that constitutes a portion that faces the other second flow path (12b); and a support part (23) that is disposed between both end parts in the width direction of the flow path formation part (2), and that is continuous with both the first outer wall part (21) and the second outer wall part (22). The first outer wall part (21) and the second outer wall part (22) are composed of an aluminum alloy plate (3) that has a specific chemical component.

Description

Heat exchanger, its manufacturing method, aluminum alloy plate for forming flow passage, tube material for heat exchanger, and outer wall material for flow passage for heat exchanger

[0001] The present invention relates to a heat exchanger, a method for manufacturing the same, an aluminum alloy plate for forming a flow passage, a tube material for a heat exchanger, and an outer wall material for a flow passage of a heat exchanger.

[0002] A heat exchanger may have a structure in which first flow paths through which a first heat transfer medium flows and second flow paths through which a second heat transfer medium flows are alternately arranged. For example, Patent Document 1 (Patent Document 1) describes a radiator having a structure in which tubes and fins are alternately stacked. The tube in Patent Document 1 is composed of an aluminum alloy clad material including a core material, a sacrificial anode material stacked on a first surface of the core material, and a brazing material stacked on a second surface of the core material. Furthermore, brazing joints made of the brazing material of the clad material are formed in gaps between the edges of the clad material in the tube and in gaps between the tube and the fins.

[0003] On the other hand, in recent years, a single-layer aluminum alloy material has been proposed that is configured to generate a small amount of melt by heating and be brazed to a mating material. For example, Patent Document 2 describes an aluminum alloy material of this type that contains 1.0 to 5.0 mass% Si, 0.01 to 2.00 mass% Fe, and the balance being Al and unavoidable impurities.

[0004] JP 2012-117107 A Japanese Patent No. 5337326

[0005] In recent years, from the viewpoint of reducing the environmental impact of heat exchanger manufacturing, it has become desirable to reuse scrap metal generated during the heat exchanger manufacturing process as a casting raw material. However, since the core material, sacrificial anode material, and brazing filler metal in the clad material of Patent Document 1 have different chemical compositions, the chemical composition of the molten metal obtained by melting the scrap metal of the clad material is different from that of the core material, the sacrificial anode material, and the brazing filler metal. Therefore, when reusing the clad material of Patent Document 1 as a casting raw material, it is necessary to use a large amount of virgin aluminum or the like to adjust the chemical composition of the molten metal within a desired range, which limits the reduction in the environmental impact.

[0006] On the other hand, the aluminum material of Patent Document 2 is configured to generate a small amount of molten liquid when heated, and therefore has the property of being prone to a decrease in strength during brazing heating. Therefore, when a tube is produced using the aluminum material of Patent Document 2, the tube easily deforms during brazing heating, which poses a problem in that it is difficult to form brazing joints in gaps between the edges of the aluminum material in the tube or in gaps between the tube and the fins.

[0007] The present invention has been made in view of the above background, and aims to provide a heat exchanger that can reduce the environmental load during the manufacturing process, suppress deformation during brazing heating, and easily form brazed joints between component parts, as well as a manufacturing method thereof, an aluminum alloy plate for forming a flow path, a tube material for a heat exchanger, and an outer wall material for a flow path of a heat exchanger.

[0008] One aspect of the present invention is a heat exchanger having a first flow path, a plurality of flow path forming sections arranged at intervals from each other, and second flow paths formed between the flow path forming sections, and configured to enable heat exchange between a heat transfer medium in the first flow path and a heat transfer medium in the second flow path, wherein the flow path forming sections have: a first outer wall section constituting a portion of an outer wall of the first flow path facing one of two second flow paths adjacent to the flow path forming section; a second outer wall section constituting a portion of the outer wall of the first flow path facing the other of the two second flow paths adjacent to the flow path forming section; and a support section arranged between both end sections in the width direction of the flow path forming sections and continuous with both the first outer wall section and the second outer wall section, The heat exchanger is configured such that the first outer wall portion and the second outer wall portion are made of an aluminum alloy plate having a chemical composition containing 1.5 mass% or more and 3.0 mass% or less of Si (silicon), 0.05 mass% or more and 0.6 mass% or less of Fe (iron), and 0.3 mass% or more and 2.0 mass% or less of Mn (manganese), with the remainder being Al (aluminum) and unavoidable impurities.

[0009] The flow path forming portion of the heat exchanger has a first outer wall portion and a second outer wall portion made of the aluminum alloy plate. Because the aluminum alloy plate is composed of a single layer of aluminum alloy having the specific chemical composition, a molten metal having the same chemical composition as the original aluminum alloy plate can be easily obtained by melting scrap of the aluminum alloy plate generated during the manufacturing process of the aluminum alloy plate or during the manufacturing process of a heat exchanger obtained using the aluminum alloy plate. Furthermore, because the first outer wall portion and the second outer wall portion are components with a high mass ratio in the heat exchanger, by constructing the first outer wall portion and the second outer wall portion from the aluminum alloy plate, the environmental impact of the manufacturing process of the heat exchanger can be easily reduced.

[0010] The flow path forming portion has a support portion disposed between both widthwise ends thereof and continuing to both the first outer wall portion and the second outer wall portion. By providing the support portion between both widthwise ends of the flow path forming portion, the rigidity of the flow path forming portion can be increased. As a result, deformation of the first outer wall portion and the second outer wall portion during brazing can be suppressed, and the first outer wall portion and the second outer wall portion can be easily maintained in contact with each other during brazing heating.

[0011] Since the aluminum alloy plate has the specific chemical composition, a small amount of molten liquid can be generated by heating, and the molten liquid generated from the aluminum alloy plate can easily form a brazing joint between the first outer wall portion and the second outer wall portion.

[0012] Therefore, according to the above-described aspect, it is possible to provide a heat exchanger that can reduce the environmental load during the manufacturing process, suppress deformation during brazing heating, and easily form brazing joints between component parts.

[0013] FIG. 1 is a front view of a heat exchanger in Example 1. FIG. 2 is a partially enlarged view of FIG. 1. FIG. 3 is a cross-sectional view taken along line III-III in FIG. 2. FIG. 4 is a partial cross-sectional view showing a main portion of a heat exchanger in Example 2. FIG. 5 is a partial cross-sectional view showing a main portion of a heat exchanger in Example 3. FIG. 6 is a perspective view of an aluminum alloy plate constituting a flow path forming portion in Example 3. FIG. 7 is a partial cross-sectional view showing a main portion of a heat exchanger in Example 4. FIG. 8 is a perspective view of an aluminum alloy plate constituting a flow path forming portion in Example 4. FIG. 9 is a perspective view of a mini-core test piece in Experimental Example 1. FIG. 10 is an explanatory diagram of a measuring device for natural electrode potential in Experimental Example 1.

[0014] (Heat Exchanger) The heat exchanger has a plurality of flow path forming portions arranged at intervals from one another. The flow path forming portions have a first outer wall portion, a second outer wall portion, and a first flow path formed by a space surrounded by the first outer wall portion and the second outer wall portion. In addition, a second flow path is formed between adjacent flow path forming portions. Therefore, the first flow paths and the second flow paths in the heat exchanger are arranged alternately, and the heat exchanger is configured to be able to perform heat exchange between the heat transfer medium in the first flow path and the heat transfer medium in the second flow path.

[0015] The flow path forming portion has a first outer wall portion, a second outer wall portion, and a support portion. The specific shape of the flow path forming portion is not particularly limited and can take various forms. For example, the flow path forming portion may be a flat tube having an oval or rectangular cross section perpendicular to its extension direction. The flow path forming portion may also have a shape in which the first flow paths and the support portions are alternately connected in the width direction. Furthermore, the flow path forming portion may have a shape in which two flat plates are stacked on top of each other.

[0016] The first outer wall portion and the second outer wall portion are made of an aluminum alloy plate having the specific chemical composition. The first outer wall portion and the second outer wall portion may be made of a common aluminum alloy plate or may be made of different aluminum alloy plates.

[0017] More specifically, for example, a flow path forming portion in which the first outer wall portion and the second outer wall portion are made of the same aluminum alloy plate can be obtained by bending a single aluminum alloy plate into a cylindrical shape and joining the end faces of the bent aluminum alloy plate by brazing. Alternatively, for example, an aluminum alloy plate constituting the first outer wall portion and an aluminum alloy plate constituting the second outer wall portion can be prepared, and the end faces of these aluminum alloy plates can be joined by brazing, thereby obtaining a flow path forming portion in which the first outer wall portion and the second outer wall portion are made of separate aluminum alloy plates. The configurations of the aluminum alloy plates constituting the first outer wall portion and the second outer wall portion will be described in more detail below.

[0018] The support portion of the flow path forming portion is disposed between both widthwise ends of the flow path forming portion and is continuous with both the first outer wall portion and the second outer wall portion. By providing the support portion continuous with both the first outer wall portion and the second outer wall portion at the specific position, the rigidity of the flow path forming portion can be structurally increased. Therefore, even if the flow path forming portion is compressed in the direction in which the first flow path and the second flow path are aligned during brazing heating, deformation of the flow path forming portion can be suppressed.

[0019] The above-mentioned "between both ends in the width direction of the flow path forming portion" refers to a position in the width direction of the flow path forming portion that can support a load applied to the center of the first outer wall portion and the center of the second outer wall portion. More specifically, for example, if the flow path forming portion has one first flow path, the support portion may be disposed between one end and the other end of the first flow path in the width direction of the flow path forming portion. Furthermore, for example, if the flow path forming portion has multiple first flow paths, the support portion may be disposed between the first flow path located at one end of the flow path forming portion and the first flow path located at the other end of the first flow paths in the width direction of the flow path forming portion.

[0020] The specific form of the support portion is not particularly limited, and various forms are possible as long as the rigidity of the flow path forming portion can be increased. For example, the flow path forming portion may have one support portion or two or more support portions. From the viewpoint of distributing the load applied to the flow path forming portion and further increasing the rigidity of the flow path forming portion, it is preferable that the flow path forming portion have multiple support portions.

[0021] The arrangement of the support parts is not particularly limited, but from the viewpoint of more easily increasing the rigidity of the flow path forming part, it is preferable that at least one support part is arranged in the center in the width direction of the flow path forming part.

[0022] The support portion may be formed from the same aluminum alloy plate as at least one of the first and second outer wall portions. That is, at least one of the first and second outer wall portions and the support portion may be formed on the same aluminum alloy plate. When the first and / or second outer wall portion and the support portion are formed on the same aluminum alloy plate, the support portion can be formed by forming a protruding portion by pressing a portion of the aluminum alloy plate or the like, and then joining the protruding portion to a mating member via brazing. In this case, various shapes, such as a dimple shape or a groove shape, can be employed as the shape of the support portion. Furthermore, the support portion can also be formed in the center of the flow passage portion in the width direction by folding back both ends of the aluminum alloy plate in the width direction and joining them to the center in the width direction.

[0023] The support portion may be made of an aluminum material different from the aluminum alloy plates constituting the first and second outer wall portions. In this case, the rigidity of the flow path forming portion can be increased by joining the support portion to the first and second outer wall portions via brazing. When the support portion is made of an aluminum material different from the first and second outer wall portions, the form of the aluminum material constituting the support portion is not particularly limited. For example, the support portion may be made of a single-layer aluminum material. In this case, the chemical composition of the aluminum material can be appropriately selected from known aluminums and aluminum alloys according to the desired strength, corrosion resistance, etc. Furthermore, the aluminum material constituting the support portion may have the same chemical composition as the aluminum alloy plates constituting the first and second outer wall portions.

[0024] The support portion may be made of a clad material including a core material and a skin material laminated on the core material. In this case, the chemical composition of the core material may be selected from known aluminum and aluminum alloys according to the desired strength, corrosion resistance, etc. The skin material may be, for example, a brazing material or a sacrificial anode material.

[0025] When the support portion is made of an aluminum material different from the aluminum alloy plates constituting the first and second outer wall portions, the shape of the support portion is not particularly limited and can be various shapes, such as a columnar or wall shape. From the viewpoint of increasing the rigidity of the flow path forming portion and performing heat exchange more efficiently, the support portion is preferably an inner fin. For example, a corrugated fin having a wavy cross-sectional shape in a cross section perpendicular to the extension direction can be used as the inner fin. The corrugated fin has multiple apexes that abut against each of the first and second outer wall portions. Therefore, by using a corrugated fin as the inner fin, the load applied to the first and second outer wall portions can be distributed to these apexes. As a result, the rigidity of the flow path forming portion can be further increased.

[0026] The heat exchanger preferably has outer fins provided in the second flow passage, and the outer fins are joined to the first outer wall portion and the second outer wall portion by brazing. By providing outer fins in the second flow passage, the spacing between adjacent flow passage forming portions is more easily maintained. Therefore, in this case, deformation of the flow passage forming portions during brazing can be more easily suppressed. Furthermore, by providing outer fins in the second flow passage, the heat exchange efficiency of the heat exchanger can be further improved.

[0027] The outer fin may be made of aluminum or an aluminum alloy. The natural electrode potential of the outer fin is preferably lower than the natural electrode potential of the first outer wall portion, the second outer wall portion, and the fillets of the brazed joints joining these outer wall portions to the outer fin. In this case, the outer fin functions as a sacrificial anode for the first outer wall portion, the second outer wall portion, and the brazed joints, thereby suppressing corrosion of these portions for a long period of time. As a result, the corrosion resistance of the entire heat exchanger can be further improved.

[0028] In the heat exchanger, the outer fin capable of functioning as a sacrificial anode may be made of an aluminum alloy containing, for example, Zn: 0.5 mass % or more and 6 mass % or less.

[0029] The outer fin may be, for example, a corrugated fin having a wave-like cross-sectional shape in a cross section perpendicular to the extension direction. The corrugated fin has multiple peaks that abut against the flow passage portion. Therefore, by using the corrugated fin as the outer fin, the load applied to the flow passage portion can be distributed to these peaks. As a result, deformation of the flow passage portion during brazing can be more effectively suppressed.

[0030] The heat exchanger can be applied to various applications. For example, the heat exchanger may be configured as an automotive heat exchanger installed in an automobile, such as a radiator, condenser, evaporator, heater core, oil cooler, intercooler, chiller, or battery cooler. The heat exchanger may also be configured as an air conditioner heat exchanger installed in an indoor unit or outdoor unit of an air conditioner. Furthermore, the heat exchanger may be configured as a heat exchanger installed in heavy machinery.

[0031] (Method for manufacturing a heat exchanger) The heat exchanger can be obtained by, for example, assembling components of a heat exchanger including a flow path forming portion to produce an assembly, and heating and brazing the assembly under conditions such that the time required to reach 575°C after reaching 450°C is 4 minutes or more and 15 minutes or less, and the time required to reach 615°C after reaching 575°C is 5 minutes or more and 40 minutes or less.

[0032] The assembly includes at least a flow path forming portion. The assembly may also include, as needed, components other than the flow path forming portions, such as a header tank that distributes the heat transfer medium to the first flow paths or that joins the heat transfer medium flowing out of the first flow paths, and outer fins that are arranged between the flow path forming portions. When assembling the assembly, a flux may be applied to the portion where a brazing joint is to be formed, as needed. Examples of the flux include KAlF ４ , K. ２ AlF ５ , K. ２ AlF ５ ・H ２ O.K. ３ AlF ６ , AlF ３ , KZnF ３ and K. ２ SiF ６ Fluoride-based fluxes such as Cs ３ AlF ６ , CsAlF ４ ・2H ２ O, Cs ２ AlF ５ ・H ２ Compounds used as fluxes for brazing aluminum, such as cesium-based fluxes such as O and chloride-based fluxes, can be used.

[0033] The components used in the assembly may be pre-etched. By etching the components to remove at least a portion of the oxide film present on the surfaces of the components, it becomes easier to form a brazed joint in the subsequent brazing heating. Pre-etching the components is particularly preferable when forming a brazed joint by so-called flux-free brazing, which does not use flux during brazing.

[0034] The etching method is not particularly limited, and for example, a method of contacting the component with an acid or alkali can be used. In the etching, the oxide film present on the surface of the component may be completely removed, or only a portion of the oxide film may be removed. After etching is completed, post-treatment such as water washing or smut removal may be performed as necessary.

[0035] After preparing the assembly, the assembly is heated and brazed under conditions such that the time required to reach 575°C from 450°C is 4 minutes or more and 15 minutes or less, and the time required to reach 615°C from 575°C is 5 minutes or more and 40 minutes or less. The aluminum alloy plate having the specific chemical composition has a liquid phase ratio of 5 mass% or more and 35 mass% or less when heated under the specific conditions. Therefore, by heating the assembly under the specific conditions, a small amount of molten liquid can be generated from the aluminum alloy plate while suppressing deformation of the flow passage forming portion. Therefore, by heating the assembly under the specific conditions, a brazed joint can be formed between the aluminum alloy plate and the components in contact with the aluminum alloy plate, thereby obtaining a heat exchanger.

[0036] From the viewpoint of suppressing oxidation of the components during brazing, the atmosphere during brazing is preferably an inert gas atmosphere. Examples of inert gas that can be used include nitrogen and argon. The dew point of the inert gas is preferably −35° C. or less, more preferably −50° C. or less, and particularly preferably −60° C. or less. The oxygen concentration in the inert gas atmosphere is preferably 200 ppm by volume or less, more preferably 100 ppm by volume or less, even more preferably 10 ppm by volume or less, and particularly preferably 5 ppm by volume or less.

[0037] (Aluminum alloy plate) The first outer wall portion and the second outer wall portion of the heat exchanger are made of a flow path forming aluminum alloy plate (hereinafter referred to as "aluminum alloy plate") having chemical components containing 1.5 mass% to 3.0 mass% of Si, 0.05 mass% to 0.6 mass% of Fe, 0.3 mass% to 2.0 mass% of Mn, and the balance being Al and unavoidable impurities. The chemical components of the aluminum alloy plate and the reasons for their limitations will be described below.

[0038] Si: 1.5% by mass or more and 3.0% by mass or less The aluminum alloy sheet contains 1.5% by mass or more and 3.0% by mass or less of Si as an essential component. By setting the Si content in the aluminum alloy sheet to 1.5% by mass or more, a molten liquid containing Al and Si can be generated during brazing, and a brazed joint can be formed between the first outer wall portion and the second outer wall portion and the components abutting these outer wall portions. The Si content in the aluminum alloy sheet is preferably 1.7% by mass or more, more preferably 1.9% by mass or more, even more preferably 2.0% by mass or more, and particularly preferably 2.2% by mass or more. In this case, the amount of molten liquid generated during brazing can be increased, thereby further improving brazing performance. If the Si content is less than 1.5% by mass, the amount of molten liquid generated during brazing is insufficient, which may result in deterioration of brazing performance.

[0039] On the other hand, if the Si content is excessively high, the amount of melting of the aluminum alloy plate during brazing increases, which may lead to a decrease in the strength of the aluminum alloy plate. As a result, the assembly may be more likely to deform during brazing. In order to avoid such problems, the Si content is set to 3.0 mass% or less. From the same viewpoint, the Si content is preferably set to 2.8 mass% or less.

[0040] When constituting a preferred range of the Si content in the aluminum alloy sheet, the above-mentioned upper and lower limits of the Si content can be combined arbitrarily. For example, the preferred range of the Si content in the aluminum alloy sheet can be 1.7 mass% or more and 3.0 mass% or less, 1.9 mass% or more and 3.0 mass% or less, 2.0 mass% or more and 3.0 mass% or less, or 2.2 mass% or more and 2.8 mass% or less.

[0041] Fe (iron): 0.05% by mass or more and 0.6% by mass or less The aluminum alloy sheet contains 0.05% by mass or more and 0.6% by mass or less of Fe as an essential component. Fe is dispersed as a crystallized precipitate in the aluminum alloy sheet and has the effect of suppressing a decrease in the strength of the aluminum alloy sheet at high temperatures. By setting the Fe content to 0.05% by mass or more, this effect can be sufficiently obtained. From the viewpoint of more effectively suppressing a decrease in the strength of the aluminum alloy sheet at high temperatures, the Fe content is preferably 0.10% by mass or more. If the Fe content is less than 0.05% by mass, the strength of the aluminum alloy sheet at high temperatures may decrease, and the assembly may be more likely to deform during brazing. Furthermore, in this case, it becomes necessary to use high-purity metal as a raw material for the aluminum alloy sheet, which may increase the material cost of the aluminum alloy sheet.

[0042] On the other hand, if the Fe content is excessively high, coarse intermetallic compounds are likely to be formed during the manufacturing process of the aluminum alloy sheet, which may result in a decrease in the manufacturability of the aluminum alloy sheet. In addition, in this case, the crystal grains of the Al matrix are likely to be refined by recrystallization during brazing. As a result, the grain boundary density of the Al matrix increases, which may make the aluminum alloy sheet more susceptible to buckling. These problems can be easily avoided by setting the Fe content in the aluminum alloy sheet to 0.6 mass% or less.

[0043] Mn: 0.3% by mass or more and 2.0% by mass or less The aluminum alloy sheet contains 0.3% by mass or more and 2.0% by mass or less of Mn as an essential component. Mn forms an Al-Mn-Si intermetallic compound in the aluminum alloy sheet, and has the effect of improving the strength of the aluminum alloy sheet by dispersion strengthening. Mn also dissolves in the Al matrix, and has the effect of improving the strength of the aluminum alloy sheet by solid solution strengthening.

[0044] By setting the Mn content in the aluminum alloy sheet to 0.3 mass% or more, the strength of the aluminum alloy sheet can be improved by dispersion strengthening and solid-solution strengthening. Furthermore, the dispersion strengthening and solid-solution strengthening described above can suppress a decrease in strength, buckling, and deformation of the aluminum alloy sheet during brazing. As a result, deformation of the assembly during brazing can be suppressed. If the Mn content is less than 0.3 mass%, the effect of improving strength by Mn is reduced, and the assembly may be more likely to deform during brazing.

[0045] On the other hand, if the Mn content is excessively high, coarse intermetallic compounds are likely to be formed during the manufacturing process of the aluminum alloy sheet. If rolling is performed while these coarse intermetallic compounds are present, pinholes may be more likely to occur. In order to avoid such problems, the Mn content is set to 2.0 mass% or less.

[0046] In addition to the above-mentioned essential components, the aluminum alloy plate may contain, as optional components, one or more elements selected from the group consisting of Cu (copper): 0.8% by mass or less, Zn (zinc): 6.0% by mass or less, Ti (titanium): 0.3% by mass or less, Mg (magnesium): 0.2% by mass or less, V (vanadium): 0.3% by mass or less, Zr (zirconium): 0.3% by mass or less, Cr (chromium): 0.3% by mass or less, Bi (bismuth): 0.1% by mass or less, Ni (nickel): 0.6% by mass or less, Sn (tin): 0.3% by mass or less, In (indium): 0.3% by mass or less, Sr (strontium): 0.1% by mass or less, Na (sodium): 0.1% by mass or less, Sb (antimony): 0.3% by mass or less, and Ca (calcium): 0.5% by mass or less.

[0047] Cu: 0.8% by mass or less The aluminum alloy sheet may contain 0.8% by mass or less of Cu as an optional component. Cu dissolves in the Al matrix to improve the strength of the aluminum alloy sheet. Cu is also likely to be concentrated in the brazed joint formed after brazing, and has the effect of increasing the noble potential of the brazed joint.

[0048] By increasing the Cu content in the aluminum alloy sheet to more than 0 mass%, the strength of the aluminum alloy sheet can be further improved, the potential of the brazing joint can be made noble, and the corrosion resistance of the brazing joint can be further improved. From the viewpoint of more reliably obtaining these effects, the Cu content in the aluminum alloy sheet is preferably 0.05 mass% or more, more preferably 0.1 mass% or more, and even more preferably 0.3 mass% or more.

[0049] On the other hand, by setting the Cu content to 0.8 mass % or less, more preferably 0.7 mass % or less, the amount of melting of the aluminum alloy sheets during brazing can be easily adjusted within an appropriate range, and as a result, deformation of the assembly during brazing can be more easily suppressed.

[0050] When constituting a preferred range of the Cu content in the aluminum alloy sheet, the above-mentioned upper and lower limits of the Cu content can be combined arbitrarily. For example, the preferred range of the Cu content in the aluminum alloy sheet can be 0 mass% or more and 0.8 mass% or less, 0.05 mass% or more and 0.8 mass% or less, 0.1 mass% or more and 0.8 mass% or less, 0.1 mass% or more and 0.7 mass% or less, or 0.3 mass% or more and 0.7 mass% or less.

[0051] The sum of the Fe content and the Cu content in the aluminum alloy plate is preferably more than 0.65 mass%, more preferably 0.68 mass% or more, and even more preferably 70 mass% or more. In this case, the strength of the aluminum alloy plate can be further improved. As a result, deformation of the assembly during brazing can be more easily suppressed. Meanwhile, the sum of the Fe content and the Cu content in the aluminum alloy plate can be 1.4 mass% or less, 1.2 mass% or less, 1.0 mass% or less, or 0.80 mass% or less.

[0052] When determining the preferred range of the total content of Fe and Cu in the aluminum alloy sheet, the above-mentioned upper and lower limits of the total content of Fe and Cu can be combined arbitrarily. For example, the preferred range of the total content of Fe and Cu can be more than 0.65% by mass and not more than 1.4% by mass, more than 0.65% by mass and not more than 1.2% by mass, 0.68% by mass or more and not more than 1.0% by mass, 0.68% by mass or more and not more than 1.0% by mass, or 0.70% by mass or more and not more than 0.80% by mass.

[0053] Zn: 6.0% by mass or less The aluminum alloy plate may contain 6.0% by mass or less of Zn as an optional component. Zn has the effect of making the potential of the aluminum alloy plate less noble. Therefore, by adding 6.0% by mass or less of Zn to the aluminum alloy plate, the potential balance between the aluminum alloy plate and other components can be more easily maintained within an appropriate range. As a result, the corrosion resistance of the entire heat exchanger can be further improved.

[0054] From the viewpoint of further improving the corrosion resistance of the heat exchanger, the aluminum alloy sheet preferably contains Cu: 0.1 mass % to 0.8 mass % and Zn: 1.0 mass % or less. In this case, the natural electrode potential of the brazed joint formed between the aluminum alloy sheet and another component can be appropriately made noble, thereby improving the self-corrosion resistance of the brazed joint. Therefore, by joining the aluminum alloy sheet to a component that can function as a sacrificial anode for the aluminum alloy sheet, such as an outer fin, via such brazing, the joined state between the two can be maintained for a long period of time. As a result, the corrosion resistance of the entire heat exchanger can be further improved.

[0055] From the viewpoint of more reliably obtaining the above-mentioned effects, the Cu content in the aluminum alloy plate is preferably 0.2% by mass or more and 0.8% by mass or less, more preferably 0.3% by mass or more and 0.8% by mass or less, and even more preferably 0.4% by mass or more and 0.8% by mass or less. From the same viewpoint, the Zn content in the aluminum alloy plate is preferably 0.7% by mass or less, more preferably 0.5% by mass or less, and even more preferably 0.3% by mass or less.

[0056] The above-mentioned preferred ranges of the Cu content and the Zn content can be arbitrarily combined. For example, the aluminum alloy sheet may contain 0.2% by mass or more and 0.8% by mass or less of Cu and 0.7% by mass or less of Zn, 0.3% by mass or more and 0.8% by mass or less of Cu and 0.5% by mass or less of Zn, or 0.4% by mass or more and 0.8% by mass or less of Cu and 0.3% by mass or less of Zn.

[0057] Mg: 0.2% by mass or less The aluminum alloy sheet may contain 0.2% by mass or less of Mg as an optional component. Mg has the effect of destroying oxide films present on the surface of the aluminum alloy sheet and on the surfaces of components to be joined to the aluminum alloy sheet. Therefore, by adding 0.2% by mass or less of Mg to the aluminum alloy sheet, brazing of an assembly can be performed by so-called flux-free brazing, which is brazing without using flux. From the viewpoint of further improving brazeability in flux-free brazing, the Mg content in the aluminum alloy sheet is preferably 0.005% by mass or more and 0.2% by mass or less.

[0058] On the other hand, in a so-called flux brazing method in which brazing is performed using a flux, the flux used for brazing reacts with Mg, which may lead to deterioration of brazability. From the viewpoint of more easily avoiding such a problem, it is preferable that the Mg content in the aluminum alloy sheet is 0.05 mass% or less.

[0059] Ti: 0.3% by mass or less, V: 0.3% by mass or less The aluminum alloy sheet may contain, as optional components, one or two of Ti: 0.3% by mass or less and V: 0.3% by mass or less. Ti and V have the effect of dissolving in the Al matrix to improve the strength of the aluminum alloy sheet. Furthermore, Ti and V are distributed in layers in the aluminum alloy sheet and have the effect of suppressing the progression of corrosion in the thickness direction of the aluminum alloy sheet. On the other hand, if the Ti content or V content is excessively high, coarse crystals are likely to be formed during the manufacturing process of the aluminum alloy sheet, which may result in a decrease in plastic workability.

[0060] By setting the Ti content and the V content in the aluminum alloy plate to preferably 0.3 mass% or less, more preferably 0.2 mass% or less, the strength and self-corrosion resistance of the aluminum alloy plate can be further improved while avoiding the formation of coarse crystallized particles.

[0061] Zr: 0.3 mass% or less The aluminum alloy sheet may contain 0.3 mass% or less of Zr as an optional component. Zr increases the strength of the aluminum alloy sheet before and after brazing, and also coarsens the crystal grain size after brazing, thereby improving high-temperature buckling resistance and brazeability. On the other hand, if the Zr content in the aluminum alloy sheet is excessively high, coarse crystals are likely to be generated during the manufacturing process of the aluminum alloy sheet.

[0062] By setting the Zr content in the aluminum alloy sheet within the specific range, the strength of the aluminum alloy sheet before and after brazing can be further improved while avoiding the formation of coarse crystallized particles, and in this case, deformation of the assembly during brazing can be more effectively suppressed and brazability can be further improved.

[0063] Cr: 0.3 mass% or less The aluminum alloy sheet may contain 0.3 mass% or less of Cr as an optional component. Cr dissolves in the Al matrix to improve the strength of the aluminum alloy sheet. Furthermore, when an aluminum alloy sheet containing Cr is heated, Al-Cr intermetallic compounds precipitate in the aluminum alloy sheet. These precipitates coarsen the crystal grains after heating. On the other hand, if the Cr content in the aluminum alloy sheet is excessively high, coarse crystals are likely to be generated during the manufacturing process of the aluminum alloy sheet.

[0064] By setting the Cr content in the aluminum alloy plate within the specific range, the strength of the aluminum alloy plate can be improved while avoiding the formation of coarse crystallized particles, and the crystal grains after heating can be coarsened.

[0065] Bi: 0.1% by mass or less The aluminum alloy sheet may contain 0.1% by mass or less of Bi as an optional component. Bi has the effect of improving the fluidity of the melt generated by brazing heat. Bi also has the effect of weakening the oxide film present on the surface of the aluminum alloy sheet and on the surface of the component to be joined to the aluminum alloy sheet. Therefore, by adding 0.1% by mass or less of Bi to the aluminum alloy sheet, brazing of an assembly can be performed by flux-free brazing. From the viewpoint of further improving brazeability in flux-free brazing, it is preferable that the aluminum alloy sheet contain both 0.1% by mass or less of Bi and 0.2% by mass or less of Mg.

[0066] Ni: 0.6% by mass or less The aluminum alloy sheet may contain 0.6% by mass or less of Ni as an optional component. Ni forms intermetallic compounds in the aluminum alloy sheet and has the effect of improving the strength of the aluminum alloy sheet after brazing through dispersion strengthening. On the other hand, if the Ni content is excessively high, coarse intermetallic compounds are likely to be formed in the aluminum alloy sheet, which may lead to deterioration of plastic workability. In addition, this may lead to a decrease in the self-corrosion resistance of the aluminum alloy sheet. By setting the Ni content in the aluminum alloy sheet to 0.6% by mass or less, it is possible to avoid these problems and further improve the strength of the aluminum alloy sheet after brazing.

[0067] Sn: 0.3 mass% or less, In: 0.1 mass% or less The aluminum alloy sheet may contain, as optional components, one or two of Sn: 0.3 mass% or less and In: 0.1 mass% or less. Sn and In have the effect of making the natural electrode potential of the aluminum alloy sheet less noble. By setting the Sn and In contents in the aluminum alloy sheet within the specific ranges, the natural electrode potential of the aluminum alloy sheet can be more easily adjusted within a desired range.

[0068] Sr: 0.1% by mass or less, Na: 0.1% by mass or less, Sb: 0.3% by mass or less, Ca: 0.5% by mass or less. The aluminum alloy sheet may optionally contain one or more elements selected from the group consisting of Sr: 0.1% by mass or less, Na: 0.1% by mass or less, Sb: 0.3% by mass or less, and Ca: 0.5% by mass or less. These elements have the effect of refining Si particles in the aluminum alloy sheet and uniformly dispersing the Si particles on the surface of the aluminum alloy sheet. Since Si particles serve as starting points for the formation of a molten liquid, uniformly dispersing the Si particles on the surface of the aluminum alloy sheet allows a uniform molten liquid to be formed on the surface of the aluminum alloy sheet, making it easier to form a brazed joint between the aluminum alloy sheet and abutting components. The contents of Sr, Na, Sb, and Ca are each preferably 0.05% by mass or less.

[0069] From the viewpoint of ensuring brazability and more effectively suppressing deformation of the assembly during brazing, it is preferable that the aluminum alloy plate has a chemical composition comprising: Si: 1.5% to 3.0% by mass, Fe: 0.05% to 0.6% by mass, Mn: 0.3% to 2.0% by mass, Cu: 0% to 0.8% by mass, and Zn: more than 0% to 6.0% by mass, with the balance being Al and unavoidable impurities. From the similar viewpoint, it is preferable that the aluminum alloy plate has a chemical composition comprising: Si: 1.5% to 3.0% by mass, Fe: 0.05% to 0.6% by mass, Mn: 0.3% to 2.0% by mass, Cu: 0.1% to 0.8% by mass, and Zn: more than 0% to 6.0% by mass, with the balance being Al and unavoidable impurities. From the same viewpoint, it is preferable that the aluminum alloy plate has a chemical composition containing Si: 1.5% by mass or more and 3.0% by mass or less, Fe: 0.05% by mass or more and 0.6% by mass or less, Mn: 0.3% by mass or more and 2.0% by mass or less, Cu: 0.1% by mass or more and 0.8% by mass or less, and Zn: more than 0% by mass and 1.0% by mass or less, the sum of the Fe content and the Cu content being more than 0.65% by mass and 1.4% by mass or less, and the balance being Al and unavoidable impurities.

[0070] From the same viewpoint, it is more preferable that the aluminum alloy plate contains Si: 1.5% by mass or more and 2.8% by mass or less, Fe: 0.05% by mass or more and 0.6% by mass or less, Mn: 0.3% by mass or more and 2.0% by mass or less, Cu: 0.3% by mass or more and 0.7% by mass or less, and Zn: more than 0% by mass and 6.0% by mass or less, the sum of the Fe content and the Cu content is 0.68% by mass or more and 1.0% by mass or less, and the balance is Al and unavoidable impurities. Furthermore, it is particularly preferable that the aluminum alloy plate has a chemical composition comprising Si: 1.5% by mass or more and 2.8% by mass or less, Fe: 0.05% by mass or more and 0.6% by mass or less, Mn: 0.3% by mass or more and 2.0% by mass or less, Cu: 0.3% by mass or more and 0.7% by mass or less, Zn: more than 0% by mass and 6.0% by mass or less, and Sr: 0.1% by mass or less, wherein the sum of the Fe content and the Cu content is 0.68% by mass or more and 1.0% by mass or less, and the balance being Al and unavoidable impurities.

[0071] Other Elements The aluminum alloy sheet may contain elements such as Ag, B, Be, Cd, Co, Ga, Ge, Hg, Li, Mo, P, Pb, and Y as unavoidable impurities. The content of these elements as unavoidable impurities is usually 0.05% by mass or less for each element. The total amount of unavoidable impurities contained in the aluminum alloy sheet is preferably 0.15% by mass or less.

[0072] Thickness The thickness of the aluminum alloy plate can be appropriately set depending on the application and performance of the heat exchanger, the pressure of the heat transfer medium, etc. For example, the thickness of the aluminum alloy plate may be 0.03 mm or more and 5.0 mm or less.

[0073] The aluminum alloy sheet may be produced by a continuous casting method or by rolling an ingot obtained by DC casting.

[0074] As the continuous casting method, a twin-roll continuous casting and rolling method, a twin-belt continuous casting method, etc. can be used. When the aluminum alloy sheet is produced by the twin-roll continuous casting and rolling method, the casting speed is preferably 0.5 m / min or more and 3 m / min or less. In the twin-roll continuous casting and rolling method, by setting the casting speed to 0.5 m / min or more, the cooling rate during casting can be sufficiently increased, and the second-phase particles in the aluminum alloy sheet can be easily refined. Furthermore, by setting the casting speed to 3 m / min or less, the molten metal can be sufficiently cooled and solidified during casting.

[0075] The temperature of the molten metal during casting is preferably 650°C or higher and 800°C or lower, and more preferably 680°C or higher and 750°C or lower. By setting the temperature of the molten metal to preferably 650°C or higher, more preferably 680°C or higher, it is possible to avoid the formation of large crystals in the molten metal. Furthermore, by setting the temperature of the molten metal to preferably 800°C or lower, more preferably 750°C or lower, it is possible to sufficiently cool and solidify the molten metal during casting.

[0076] The thickness of the cast plate obtained by the continuous casting method is preferably 2 mm to 10 mm, more preferably 4 mm to 8 mm. By making the thickness of the cast plate preferably 2 mm or more, more preferably 4 mm or more, a sound cast plate can be stably produced. Furthermore, by making the thickness of the cast plate preferably 10 mm or less, more preferably 8 mm or less, the cast plate can be easily wound onto a roll after casting.

[0077] A cast plate obtained by a continuous casting method may be used as the aluminum alloy plate as it is. Alternatively, the aluminum alloy plate having a desired thickness and temper can be obtained by adjusting the thickness and temper of the cast plate by cold rolling, heat treatment, or the like. The aluminum alloy plate may have a temper represented by the temper symbol O, H1n, or H2n, for example. From the viewpoint of suppressing erosion during brazing, the aluminum alloy plate preferably has a temper represented by the temper symbol H1n or H2n.

[0078] Furthermore, when the aluminum alloy sheet is produced by rolling an ingot obtained by DC casting, the casting speed during casting is preferably 20 mm / min or more and 100 mm / min or less, and more preferably 30 mm / min or more and 80 mm / min or less. In DC casting, by setting the casting speed to preferably 20 mm / min or more, more preferably 30 mm / min or more, the cooling rate during casting can be sufficiently increased, and the second-phase particles in the aluminum alloy sheet can be easily refined. Furthermore, by setting the casting speed to preferably 100 mm / min or less, more preferably 80 mm / min or less, the molten metal can be sufficiently cooled and solidified during casting.

[0079] When the slab is produced by DC casting, the thickness of the slab is preferably 600 mm or less, more preferably 500 mm or less, in which case the cooling rate during casting can be sufficiently increased, and the second-phase particles in the aluminum alloy sheet can be easily refined.

[0080] After producing an ingot by DC casting, the ingot can be rolled to obtain an aluminum alloy sheet having a desired thickness. In rolling the ingot, hot rolling and cold rolling may be performed in appropriate combination. Furthermore, between before rolling and the completion of rolling, heat treatments such as homogenization and annealing may be performed as necessary to adjust the temper of the aluminum alloy sheet. The aluminum alloy sheet may have a temper represented by, for example, a temper symbol O, H1n, or H2n. From the viewpoint of suppressing erosion during brazing, the aluminum alloy sheet preferably has a temper represented by a temper symbol H1n or H2n.

[0081] (Heat Exchanger Tube) A heat exchanger tube can be obtained by subjecting the aluminum alloy plate to a forming process. The shape of the heat exchanger tube can take various forms. For example, a cylindrical heat exchanger tube can be obtained by forming the aluminum alloy plate into a cylindrical shape. The heat exchanger tube can be, for example, a flat tube having an oval cross-sectional shape perpendicular to its extension direction. In this case, for example, it is preferable that a convex portion is formed on at least one of two opposing flat plate portions of the flat tube, and the tip of the convex portion abuts the other flat plate portion. By brazing such a tube, a support portion can be formed on the tube, including a convex portion and a brazed joint that joins the convex portion and the flat plate portion.

[0082] Furthermore, for example, by folding back both ends of the aluminum alloy plate in the width direction toward the center, a heat exchanger tube material having a substantially B-shaped cross section perpendicular to the extension direction can be obtained. The tube material thus obtained has a flat portion originating from the center of the aluminum alloy plate in the width direction and a folded portion formed by folding back both ends of the aluminum alloy plate in the width direction toward the center. The tip of the folded portion faces the flat portion. By brazing a heat exchanger tube material having such a shape, a brazed joint is formed between the flat portion and the tip of the folded portion, and a support portion including the tip of the folded portion and the brazed joint can be formed on the tube material. Therefore, the tube material can easily suppress deformation of the heat exchanger during brazing heating.

[0083] (Heat Exchanger Flowpath Outer Wall Material) Furthermore, by subjecting the aluminum alloy plate to a forming process, a heat exchanger flowpath outer wall material constituting the outer wall of a heat exchanger flowpath for a heat transfer medium can be obtained. The flowpath outer wall material may have, for example, multiple grooves and connecting portions connecting adjacent grooves. Two outer wall materials having such a shape can be stacked together so that a space is formed between the grooves of one flowpath outer wall material and the connecting portions of one flowpath outer wall material abut against the connecting portions of the other flowpath outer wall material, and then brazed to form a flowpath for a heat transfer medium in the space surrounded by the grooves. Furthermore, brazing in this manner can form a support portion between adjacent flowpaths, including a connecting portion and a brazed joint that joins the connecting portions. Therefore, the flowpath outer wall material can easily suppress deformation of the heat exchanger during brazing heating.

[0084] Furthermore, the flow path outer wall material may have, for example, a flat plate portion and a peripheral portion provided around the flat plate portion, and the peripheral portion may be bent so as to protrude in one direction in the thickness direction of the flat plate portion relative to the flat plate portion. By stacking multiple flow path outer wall materials having such a shape so that their peripheral portions abut, a flow path for the heat transfer medium can be formed between the flow path outer wall materials. Furthermore, it is preferable that the flat plate portion of the flow path outer wall material having such a shape has a convex portion formed thereon, and the convex portion is configured to abut against the flat plate portion of the flow path outer wall material adjacent to the flow path outer wall material. By stacking such flow path outer wall materials and then brazing them, a support portion including the convex portion and the brazed joint joining the convex portion and the flat plate portion can be formed.

[0085] Example 1 An example of the heat exchanger will be described with reference to Figures 1 to 3. As shown in Figures 1 and 2, the heat exchanger 1 of this example includes a first flow path 11, a plurality of flow path forming sections 2 arranged at intervals from one another, and second flow paths 12 formed between the flow path forming sections 2, and is configured to enable heat exchange between the heat transfer medium in the first flow path 11 and the heat transfer medium in the second flow path 12. As shown in Figures 2 and 3, the flow path forming section 2 includes a first outer wall section 21 that constitutes a portion of the outer wall of the first flow path 11 facing one second flow path 12a of two second flow paths 12 (12a, 12b) adjacent to the flow path forming section 2, a second outer wall section 22 that constitutes a portion of the outer wall of the first flow path 11 facing the other second flow path 12b of the two second flow paths 12 adjacent to the flow path forming section 2, and a support section 23 that is arranged between both ends of the flow path forming section 2 in the width direction and is continuous with both the first outer wall section 21 and the second outer wall section 22. The first outer wall portion 21 and the second outer wall portion 22 are composed of an aluminum alloy plate 3 having a chemical composition containing Si: 1.5 mass% or more and 3.0 mass% or less, Fe: 0.05 mass% or more and 0.6 mass% or less, Mn: 0.3 mass% or more and 2.0 mass% or less, with the remainder being Al and unavoidable impurities.

[0086] 1, the heat exchanger 1 of this example is a so-called parallel flow type heat exchanger having a stack 10 in which flow path forming portions 2 and outer fins 13 are alternately stacked, and headers 14 arranged at both ends of the stack 10 in the extension direction of the flow path forming portions 2. Although not shown in the figure, a brazing joint is formed between the flow path forming portions 2 and the headers 14, and the flow path forming portions 2 and the headers 14 are joined via the brazing joint.

[0087] As shown in Fig. 3 , the flow path forming portion 2 in the heat exchanger 1 of this example has flat tubes 24 and inner fins 25 arranged inside the flat tubes 24. The flat tubes 24 have an oval cross-sectional shape in a cross section perpendicular to the extension direction thereof. A first flow path 11 is formed inside the flat tubes 24. The flat tubes 24 of this example are made of, for example, a single aluminum alloy plate 3, and end faces of the aluminum alloy plate 3 are joined together via a brazing joint 241.

[0088] As shown in Fig. 2 , a second flow path 12 is formed between adjacent flat tubes 24 in the heat exchanger 1. An outer fin 13 is also arranged in the second flow path 12. The outer fin 13 in this example is a corrugated fin having fin crests 131 that abut against the flow path forming portion 2 and fin intermediate portions 132 that connect adjacent fin crests 131. As shown in Fig. 2 , a brazed joint 133 is formed between the flat tube 24 and the fin crest 131 of the outer fin 13, and the flat tube 24 and the outer fin 13 are joined via the brazed joint.

[0089] 2 and 3 , the first outer wall portion 21 of the flow path forming portion 2 in the heat exchanger 1 of this example is composed of a portion of the outer wall of each flat tube 24 that faces one second flow path 12a of the two second flow paths 12 (12a, 12b) that face the flat tube 24. In addition, the second outer wall portion 22 of the flow path forming portion 2 is composed of a portion of the outer wall of each flat tube 24 that faces the other second flow path 12b of the two second flow paths 12 that face the flat tube 24.

[0090] As shown in FIG. 3 , the inner fin 25 of this example is a corrugated fin having a first fin crest 251 abutting the first outer wall portion 21, a second fin crest 252 abutting the second outer wall portion 22, and a fin intermediate portion 253 connecting the first fin crest 251 and the second fin crest 252. The first fin crest 251 is joined to the first outer wall portion 21 via a brazed joint 254. Similarly, the second fin crest 252 is joined to the second outer wall portion 22 via a brazed joint 255. The fin height of the inner fin 25, i.e., the height from the first fin crest 251 to the second fin crest 252, can be set appropriately within a range of, for example, 1 mm to 50 mm. Furthermore, the fin pitch of the inner fin 25, i.e., the distance from any one first fin crest 251 to the first fin crest 251 adjacent to that first fin crest 251, can be set appropriately within a range of, for example, 1 mm to 50 mm.

[0091] The inner fin 25 in this example is connected to both the first outer wall portion 21 and the second outer wall portion 22 via brazed joints 254, 255. Therefore, the support portion 23 of the flow path forming portion 2 includes the inner fin 25, a brazed joint 254 that joins the inner fin 25 to the first outer wall portion 21, and a brazed joint 255 that joins the inner fin 25 to the second outer wall portion 22. The flow path forming portion 2 in this example is obtained, for example, by placing the inner fin 25 inside a tube made of an aluminum alloy plate 3 bent into a tubular shape, and then brazing the aluminum alloy plate 3 and the inner fin 25.

[0092] The flow path forming portion 2 of the heat exchanger 1 of this example has a first outer wall portion 21 and a second outer wall portion 22 made of an aluminum alloy plate 3. Because the aluminum alloy plate 3 is composed of a single layer of an aluminum alloy having the specific chemical composition, by melting scrap aluminum alloy plate 3 generated during the manufacturing process of the heat exchanger 1, it is possible to easily obtain a molten metal having the same chemical composition as the original aluminum alloy plate 3. Furthermore, because the first outer wall portion 21 and the second outer wall portion 22 are components with a high mass ratio within the heat exchanger 1, by forming the first outer wall portion 21 and the second outer wall portion 22 from the aluminum alloy plate 3, the environmental impact during the manufacturing process of the heat exchanger 1 can be easily reduced.

[0093] The flow path forming portion 2 also has inner fins 25 as support portions 23 that are disposed between both widthwise ends of the flow path forming portion 2 and are joined to both the first outer wall portion 21 and the second outer wall portion 22. By providing the support portions 23 between both widthwise ends of the flow path forming portion 2 in this manner, the rigidity of the flow path forming portion 2 can be increased. As a result, deformation of the first outer wall portion 21 and the second outer wall portion 22 during brazing can be suppressed, and the first outer wall portion 21 and the second outer wall portion 22 can be easily maintained in contact with each other during brazing heating.

[0094] The aluminum alloy plate 3 constituting the flat tubes 24 in the flow passage forming portion 2 has the specific chemical composition, and therefore can generate a small amount of molten liquid when heated. Therefore, the molten liquid generated from the aluminum alloy plate 3 can easily form brazing joints between the components of the heat exchanger 1.

[0095] The heat exchanger 1 also has outer fins 13 provided in the second flow passage 12, and the outer fins 13 are joined to the first outer wall portion 21 and the second outer wall portion 22 by brazing joints 133. By providing the outer fins 13 in the second flow passage 12 in this way, the spacing between adjacent flow passage forming portions 2 is more easily maintained. As a result, deformation of the flow passage forming portions 2 during brazing can be more easily suppressed. Furthermore, by providing the outer fins 13 in the second flow passage 12, the heat exchange efficiency of the heat exchanger 1 can be further improved.

[0096] As described above, the heat exchanger 1 of this embodiment can reduce the environmental load during the manufacturing process, suppress deformation during brazing heating, and easily form brazed joints between the component parts.

[0097] (Example 2) In this example, another example of the flow path forming portion will be described. Note that, among the symbols used in the examples after this example, the same symbols as those used in the previous examples represent the same components as those in the previous examples, unless otherwise specified. Specifically, as shown in FIG. 4 , the heat exchanger 102 of this example is a so-called parallel flow type heat exchanger that has a stack 10 in which flow path forming portions 202 and outer fins 13 are alternately stacked, and headers (not shown) arranged at both longitudinal ends of the flow path forming portions 202 of the stack 10.

[0098] The flow path forming portion 202 in this example is made of a single aluminum alloy plate 3, and has a substantially B-shaped cross section perpendicular to the extension direction. More specifically, the flow path forming portion 202 is formed by folding back both ends in the width direction of the aluminum alloy plate 3 toward the center, and has a flat plate portion 26 originating from the center part in the width direction of the aluminum alloy plate 3, and two folded back portions 27 connected to the flat plate portion 26 at both ends in the width direction of the flow path forming portion 202.

[0099] A tip 271 of the folded portion 27 abuts against the flat plate portion 26 at the center in the width direction of the flow path forming portion 202, and a brazed joint 272 is formed between the tip 271 of the folded portion 27 and the flat plate portion 26. Furthermore, a space in the flow path forming portion 202 surrounded by the flat plate portion 26 and the folded portion 27 constitutes the first flow path 11. The flow path forming portion 202 of this example is obtained, for example, by forming the folded portion 27 by folding both ends in the width direction of the aluminum alloy plate 3 toward the center, and then brazing the tip 271 of the folded portion 27 to the flat plate portion 26.

[0100] A second flow path 12 is formed between adjacent flow path forming portions 202 in the heat exchanger 102. An outer fin 13 is disposed in the second flow path 12. The outer fin 13 is joined to the flow path forming portion 202 via brazing (not shown).

[0101] In the heat exchanger 102 of this example, the first outer wall portion 21 of the flow path forming portion 202 is made up of the folded portion 27 of each flow path forming portion 202, and the second outer wall portion 22 is made up of the flat plate portion 26. In addition, the support portion of the flow path forming portion 202 includes a brazed joint 262 that joins the tip 271 of the folded portion 27 to the flat plate portion 26, and is disposed at the center in the width direction of the flow path forming portion 202. The configurations of other parts of the heat exchanger 102 of this example are similar to the configurations of the corresponding parts in the heat exchanger 1 of the first embodiment.

[0102] The heat exchanger 102 of this embodiment can achieve the same effects as the heat exchanger 1 of the first embodiment.

[0103] Third Embodiment In this embodiment, a heat exchanger 103 according to another embodiment of the present invention will be described. As shown in Fig. 5 , the heat exchanger 103 is a so-called parallel flow heat exchanger having a stack 10 in which the flow path forming portions 203 and the outer fins 13 are alternately stacked, and headers (not shown) disposed at both ends of the stack 10 in the direction in which the flow path forming portions 203 extend.

[0104] The flow path forming portion 203 in this example is formed by a space surrounded by a first outer wall portion 21 and a second outer wall portion 22, and has a plurality of first flow paths 11 arranged at intervals in the width direction of the flow path forming portion 203. In addition, support portions 23 are provided between adjacent first outer wall portions 21 and between adjacent second outer wall portions 22.

[0105] As shown in Fig. 6, the flow path forming portion 203 is composed of two aluminum alloy plates 303 (303a, 303b) each having a plurality of grooves 31 and a connecting portion 32 connecting adjacent grooves 31. The aluminum alloy plates 303 constituting the flow path forming portion 203 have the specific chemical composition. As shown in Fig. 5, the flow path forming portion 203 of this example can be obtained, for example, by overlapping two aluminum alloy plates 303 with the grooves 31 facing each other, and then joining the connecting portions 32 via brazing (not shown).

[0106] A second flow path 12 is formed between adjacent flow path forming portions 203 in the heat exchanger 103. An outer fin 13 is disposed in the second flow path 12. The outer fin 13 is joined to the flow path forming portion 203 via brazing (not shown).

[0107] The first outer wall portion 21 of the flow path forming portion 203 in the heat exchanger 103 of this example is formed from a groove portion 31 in one aluminum alloy plate 303a of two aluminum alloy plates 303 (303a, 303b) that constitute the flow path forming portion 203. The second outer wall portion 22 of the flow path forming portion 203 is formed from a groove portion 31 in the other aluminum alloy plate 303b of the two aluminum alloy plates 303 that constitute the flow path forming portion 203. The support portion 23 of the flow path forming portion 203 includes connection portions 32 of the two aluminum alloy plates 303 and brazing joints that join the connection portions 32 together, and is disposed between both ends of the flow path forming portion 203 in the width direction. The configurations of other parts of the heat exchanger 103 of this example are similar to the configurations of the corresponding parts of the heat exchanger 103 of Example 1.

[0108] The heat exchanger 103 of this embodiment can achieve the same effects as the heat exchanger 1 of the first embodiment.

[0109] Example 4 In this example, an example of a plate-type heat exchanger will be described. As shown in Fig. 7 , the heat exchanger 104 of this example is a so-called plate-type heat exchanger that includes two plates 28 (28a, 28b) made of aluminum alloy plates 3 having the specific chemical composition, a plurality of flow path forming portions 204 each having a first fin 15 interposed between the plates 28, and second fins 16, and the flow path forming portions 204 and the second fins 16 are alternately stacked.

[0110] The flow path forming portion 204 of this example has two plates 28, a first plate 28a and a second plate 28b. The first flow path 11 of the flow path forming portion 204 is formed by a space surrounded by the first plate 28a and the second plate 28b. As shown in FIG. 8 , the plate 28 is formed from an aluminum alloy plate 304 having a flat plate portion 281 and a peripheral portion 282 provided around the flat plate portion 281. The peripheral portion 282 of the aluminum alloy plate 304 is bent so as to protrude in one direction in the thickness direction of the flat plate portion 281 relative to the flat plate portion 281. Furthermore, as shown in FIG. 7 , the peripheral portion 282 of the first plate 28a and the peripheral portion 282 of the second plate 28b are joined via a brazed joint 283.

[0111] Specifically, the first fin 15 in this example is a corrugated fin having a first fin top 151 abutting against the flat portion 281 of the first plate 28a, a second fin top 152 abutting against the flat portion 281 of the second plate 28b, and a fin intermediate portion (not shown) connecting the first fin top 151 and the second fin top 152. The first fin top 151 is joined to the flat portion 281 of the first plate 28a via a brazed joint 153. Similarly, the second fin top 152 is joined to the flat portion 281 of the second plate 28b via a brazed joint 154.

[0112] The flow path forming portion 204 in this example is obtained, for example, by brazing the peripheral portion 282 of the first plate 28a to the peripheral portion 282 of the second plate 28b while sandwiching the first fin 15 between the flat portion 281 of the first plate 28a and the flat portion 281 of the second plate 28b.

[0113] In the heat exchanger 104 of this example, the peripheral edge 282 of the second plate 28b of each flow path forming portion 204 is joined to the peripheral edge 282 of the first plate 28a in the flow path forming portion 204 adjacent to the flow path forming portion 204 in question via a brazing joint 284. The space surrounded by the second plate 28b of each flow path forming portion 204 and the first plate 28a in the flow path forming portion 204 adjacent to the flow path forming portion 204 in question constitutes the second flow path 12.

[0114] A second fin 16 made of a corrugated fin having a shape similar to that of the first fin 15 is disposed in the second flow path 12. A brazed joint 162 is formed between the flow path forming portion 204 and a fin top portion 161 of the second fin 16, and the flow path forming portion 204 and the second fin 16 are joined via the brazed joint 162.

[0115] In the heat exchanger 104 of this example, the first outer wall portion 21 of the flow path forming portion 204 includes the flat plate portion 281 of the first plate 28a. The second outer wall portion 22 of the flow path forming portion 204 includes the flat plate portion 281 of the second plate 28b. The support portion 23 of the flow path forming portion 204 includes the first fin 15, a brazed joint 153 that joins the first fin 15 to the flat plate portion 281 of the first plate 28a, and a brazed joint 154 that joins the first fin 15 to the flat plate portion 281 of the second plate 28b.

[0116] The heat exchanger 104 of this embodiment can achieve the same effects as the heat exchanger 1 of the first embodiment.

[0117] Experimental Example 1 In this example, a mini-core test piece 105 having the shape shown in Fig. 9 was produced and the brazability was evaluated. The mini-core test piece 105 had a flow path forming portion 205 including a first outer wall portion 21, a second outer wall portion 22, and inner fins 25 serving as support portions 23, and outer fins 13 joined to the outer surfaces of the first outer wall portion 21 and the second outer wall portion 22 in the flow path forming portion 205, respectively.

[0118] The flow path forming portion 205 in this example has a cylindrical shape and is made up of two aluminum alloy plates 305 (305a, 305b) having the specific chemical composition. The first outer wall portion 21 of the flow path forming portion 205 is provided on one of the two aluminum alloy plates 305, the aluminum alloy plate 305a, and the second outer wall portion 22 is provided on the other aluminum alloy plate 305b.

[0119] The aluminum alloy plate 305 has a flat plate portion 33 located in the center in the width direction thereof, and side end portions 34 located at both ends in the width direction and continuing to the flat plate portion 33. The side end portions 34 are bent so as to protrude to one side in the thickness direction of the flat plate portion 33. In addition, the side end portion 34 of one aluminum alloy plate 305a of the two aluminum alloy plates 305 and the side end portion 34 of the other aluminum alloy plate 305b are joined via brazing (not shown).

[0120] The inner fin 25 is disposed between the first outer wall portion 21 and the second outer wall portion 22. The inner fin 25 in this example is a corrugated fin made of an aluminum alloy plate having the specific chemical composition, and has a first fin top 251 that abuts the first outer wall portion 21 and a second fin top 252 that abuts the second outer wall portion 22. The first fin top 251 is joined to the first outer wall portion 21 via a brazing joint (not shown). The second fin top 252 is joined to the second outer wall portion 22 via a brazing joint (not shown).

[0121] In addition, the outer fin 13 in this example is a corrugated fin made of an aluminum alloy plate having the specific chemical composition, and the fin top 131 of the outer fin 13 is joined to either the first outer wall portion 21 or the second outer wall portion 22 via a brazing joint 133.

[0122] Table 1 shows aluminum alloy plates A1 to A7 used to prepare the mini-core test piece 105. The method for preparing these aluminum alloy plates is, for example, as follows.

[0123] [Aluminum alloy sheets A1 and A5] The aluminum alloy sheets A1 and A5 are obtained by producing a cast sheet by a continuous casting method and then rolling the cast sheet. Specifically, a cast sheet having the chemical composition shown in Table 1 is first produced by a twin-roll continuous casting and rolling method. The temperature of the molten metal during casting may be appropriately set within a range of, for example, 650°C to 800°C. The casting speed may be appropriately set within a range of, for example, 0.5 mm / min to 2.0 mm / min. The thickness of the cast sheet is not particularly limited, but is, for example, 6 mm.

[0124] Thereafter, rolling and heat treatment are carried out in an appropriate combination depending on the desired thickness and temper. For example, to obtain an aluminum alloy plate having a thickness of 0.20 mm and tempered to H14 material, the cast plate is cold-rolled to produce a rolled plate having a thickness of 0.250 mm. Next, the rolled plate is held at a temperature of 370°C for 3 hours for intermediate annealing. The rolled plate after intermediate annealing is then further cold-rolled to a thickness of 0.200 mm. In this manner, aluminum alloy plates A1 and A5 having the chemical compositions, thicknesses, and tempers shown in Table 1 can be obtained. In Table 1, the continuous casting method is abbreviated as "CC." In addition, "Bal." in Table 1 is a symbol indicating the remainder.

[0125] [Aluminum Alloy Sheets A2 to A4 and A6 to A7] Aluminum alloy sheets A2 to A4 and A6 to A7 are obtained by DC casting an ingot, followed by rolling the ingot. Specifically, first, an ingot having the chemical composition shown in Table 1 is produced by DC casting. This ingot is held at a temperature of 500°C for 8 hours for homogenization, and then hot-rolled to produce a rolled sheet having a thickness of 3 mm. The ingot temperature at the start of hot rolling may be, for example, 480°C. Note that the holding temperature and holding time in the homogenization treatment are not limited to the above-mentioned embodiments. Hot rolling can also be performed without homogenization.

[0126] Thereafter, the rolled sheet obtained by hot rolling is subjected to an appropriate combination of rolling and heat treatment depending on the desired thickness and temper. For example, to obtain an aluminum alloy sheet having a thickness of 0.20 mm and tempered to H14 material, the rolled sheet is cold-rolled to a thickness of 0.250 mm. Next, the rolled sheet is held at a temperature of 370°C for 3 hours for intermediate annealing. The rolled sheet after intermediate annealing is then further cold-rolled to a thickness of 0.200 mm. In this manner, aluminum alloy sheets A2 to A4 and A6 to A7 having the chemical compositions, thicknesses, and tempers shown in Table 1 can be obtained. In Table 1, DC casting is abbreviated as "DC."

[0127] [Method of Manufacturing Mini-Core Specimen 105] To manufacture the mini-core specimen 105, first, aluminum alloy plates are pressed to produce the components of the mini-core specimen 105. Next, these components are degreased using acetone, and then flux is applied to the surfaces of the components. The aluminum alloy plate components are then assembled in the combinations shown in Table 2 to produce an assembly. The resulting assembly is compressed in the lamination direction of the outer fin 13 and the flow passage forming portion 205, and brazed by heating under conditions such that the time required from reaching 450°C to reaching 575°C is 4 to 15 minutes, and the time required from reaching 575°C to reaching 615°C is 5 to 40 minutes. Through the above steps, specimens S1 to S8 shown in Table 2 can be obtained.

[0128] Specimens R1 to R4 shown in Table 2 are specimens for comparison with specimens S1 to S8. Specimens R1 to R4 have the same configuration as specimens S1 to S8 except that they do not have inner fins 25. The method for producing specimens R1 to R4 is the same as the method for producing specimens S1 to S8 except that the inner fins 25 are not disposed between the first outer wall portion 21 and the second outer wall portion 22.

[0129] [Evaluation of Brazeability] The method for evaluating brazeability using the mini-core test piece 105 is as follows: First, the inner fin 25 is removed from the mini-core test piece 105 after brazing, and the length of the fillet of the brazed joint formed between the first outer wall portion 21 and the inner fin 25 and the length of the fillet of the brazed joint formed between the second outer wall portion 22 and the inner fin 25 are measured.

[0130] Then, a ratio of the length of the actually formed fillet, i.e., the sum of the length of the fillet of the brazed joint formed between the first outer wall portion 21 and the inner fin 25 and the length of the fillet of the brazed joint formed between the second outer wall portion 22 and the inner fin 25, to the length of the fillet when all of the fin crests 251, 252 of the inner fin 25 are joined to the first outer wall portion 21 and the second outer wall portion 22 is calculated. This ratio expressed as a percentage is defined as the joining rate of the inner fin 25. Specifically, the length of the fillet when all of the fin crests 251, 252 of the inner fin 25 are joined to the first outer wall portion 21 and the second outer wall portion 22 is obtained by multiplying the number of fin crests 251, 252 of the inner fin 25 by the length of the inner fin 25 in the extension direction.

[0131] In addition, the outer fin 13 is removed from the mini-core test piece 105 after brazing, and the length of the fillet of the brazed joint 133 formed between the first outer wall portion 21 and the outer fin 13 and the length of the fillet of the brazed joint (not shown) formed between the second outer wall portion 22 and the outer fin 13 are measured. Then, the joining rate of the outer fin 13 is calculated using a method similar to that for calculating the joining rate of the inner fin 25.

[0132] In the "Inner fin joining rate" and "Outer fin joining rate" columns of Table 2, the symbol "A" is entered when the joining rate is 90% or more, the symbol "B" is entered when it is 50% or more but less than 90%, and the symbol "C" is entered when it is less than 50%.

[0133]

[0134]

[0135] As shown in Tables 1 and 2, the first outer wall portion 21 and the second outer wall portion 22 of each of specimens S1 to S8 are each made of an aluminum alloy plate 305 having the specific chemical composition. These specimens also have inner fins 25 as support portions 23. Therefore, deformation of these specimens during brazing is suppressed, and brazing joints can be easily formed at any position between the inner fin 25 and the flow path forming portion 205, and between the outer fin 13 and the flow path forming portion 205.

[0136] In contrast, the test specimens R1 to R4 do not have the inner fins 25 as the support portions 23, and therefore the flow path forming portions 205 are easily deformed during brazing. As a result, the tops of the outer fins 13 are separated from the flow path forming portions 205 during brazing, making it difficult to form a brazed joint between the flow path forming portions 205 and the outer fins 13.

[0137] (Experimental Example 2) In this example, a mini-core specimen 105 having the shape shown in Fig. 9 was produced, and corrosion resistance was evaluated. In this example, aluminum alloy plates A8 to A10 used to produce the mini-core specimen 105 have the chemical compositions and thicknesses shown in Table 3. The method for producing the aluminum alloy plates A8 to A10 is the same as the method for producing the aluminum alloy plates A1 to A7 in Experimental Example 1, except that the chemical compositions and thicknesses during casting were changed as shown in Table 3.

[0138] The method for producing the mini-core specimen 105 in this example is the same as the method for producing the mini-core specimen 105 in Experimental Example 1, except that the components of the mini-core specimen 105 were produced using aluminum alloy plates A8 to A10 and combined in the combinations shown in Table 4.

[0139] [Measurement of Natural Electrode Potential] Table 4 shows the natural electrode potential of the outer fin 13, the natural electrode potential of the outer surface of the first outer wall portion 21, and the natural electrode potential of the brazed joint fillet formed between the outer fin 13 and the first outer wall portion 21 in the mini-core test specimens 105 of this example (test specimens S9 to S10). The method for measuring these natural electrode potentials is as follows. First, the inner fin 25, the second outer wall portion 22, and the outer fin 13 joined to the second outer wall portion 22 are removed from the mini-core test specimen 105. Next, the first outer wall portion 21 and the outer fin 13 joined thereto are cut to an appropriate size to prepare a test specimen. Then, the portions of the test specimen other than the potential measurement region M for the natural electrode potential are covered with a sealant.

[0140] Thereafter, the natural electrode potential of the potential measurement region M is measured as follows. A measurement device 4 shown in FIG. 10 is used to measure the natural electrode potential. The measurement device 4 has a first container 41 that holds a solution in which the test strip T is immersed, a second container 42 that holds a solution in which a reference electrode 44 is immersed, a salt bridge 43 that electrically connects the solution in the first container 41 with the solution in the second container 42, and an electrometer 54 that measures and records the potential of the potential measurement region M relative to the reference electrode 44. Note that the shape of the test strip T is shown schematically in FIG. 10.

[0141] The natural electrode potential is measured as follows: First, a 5% NaCl aqueous solution whose pH has been adjusted to 3 using acetic acid is prepared in a first container 41, and a saturated NaCl aqueous solution is prepared in a second container 42. The solutions in the first container 41 and the second container 42 are then electrically connected via a salt bridge 43. The temperatures of the solutions are set to room temperature.

[0142] Next, the test piece T and the reference electrode 44 are electrically connected to the electrometer 54. As the reference electrode 44, for example, a saturated calomel electrode (so-called SCE) can be used.

[0143] In this state, the potential measurement region M of the test piece T is immersed in the solution in the first container 41 while stirring the solution, and the reference electrode 44 is immersed in the saturated NaCl aqueous solution in the second container 42, thereby measuring the natural electrode potential (unit: mV vs. SCE) of the potential measurement region M relative to the reference electrode 44. The arithmetic mean value of the natural electrode potentials from 20 hours after the start of measurement to 24 hours after the start of measurement is defined as the natural electrode potential of the potential measurement region M.

[0144] [Evaluation of Corrosion Resistance] The corrosion resistance of the mini-core test piece 105 was evaluated as follows. First, a SWAAT test was performed using a method conforming to ASTM-G85-A3. The test period of the SWAAT test was 500 hours. After the test, the mini-core test piece 105 was visually observed to determine whether or not the outer fin 13 had peeled off and whether or not a through hole had formed in the flow path forming portion 205. If the outer fin 13 had not peeled off and no through hole had formed in the flow path forming portion 205 after the SWAAT test, the corrosion resistance was determined to be good, and the "Corrosion Resistance" column in Table 5 was recorded as "Good." Furthermore, if at least one of the outer fin 13 peeling off or the formation of a through hole had occurred after the SWAAT test, the corrosion resistance was determined to be insufficient, and the "Corrosion Resistance" column in Table 5 was recorded as "Poor."

[0145]

[0146]

[0147]

[0148] As shown in Tables 3 and 4, the first outer wall portion 21 and the second outer wall portion 22 of the test specimen S9 were made of aluminum alloy plate A8 containing 0.1 mass % or more and 0.8 mass % or less of Cu and 1.0 mass % or less of Zn. By joining the first outer wall portion 21 and the second outer wall portion 22 made of such an aluminum alloy plate to the outer fin 13, as shown in Table 4, the natural electrode potential of the outer fin 13 can be made less noble than the natural electrode potential of the first outer wall portion 21, the natural electrode potential of the second outer wall portion 22, and the natural electrode potential of the fillet of the brazed joint joining these outer wall portions to the outer fin 13. In a heat exchanger having such a natural electrode potential, the outer fin 13 functions as a sacrificial anode for the first outer wall portion 21, the second outer wall portion 22, and the brazed joint, as shown in Table 5, and therefore peeling of the outer fin 13 and formation of through holes in the first outer wall portion 21 and the second outer wall portion 22 can be suppressed for a long period of time.

[0149] In contrast, as shown in Tables 3 and 4, the first outer wall portion 21 and the second outer wall portion 22 of the test piece S10 do not contain Cu and have a relatively high Zn content. Therefore, in the test piece S10, as shown in Table 4, the natural electrode potential of the fillet of the brazed joint joining the outer wall portion and the outer fin 13 is lower than the natural electrode potential of the first outer wall portion 21, the natural electrode potential of the second outer wall portion 22, and the natural electrode potential of the outer fin 13. As a result, as shown in Table 5, the outer fin 13 is likely to peel off early. Furthermore, peeling of the outer fin 13 makes it easier for through holes to form early in the first outer wall portion 21 and the second outer wall portion 22.

[0150] The above describes aspects of the heat exchanger and its manufacturing method based on examples and experimental examples, but the specific aspects of the heat exchanger and its manufacturing method according to the present invention are not limited to the aspects of the examples, and the configuration can be changed as appropriate within the scope that does not detract from the spirit of the present invention.

[0151] For example, in Example 1, an example was shown in which the flat tube of the flow path forming portion was made of a single aluminum alloy plate, but the flat tube could also be made by joining two aluminum alloy plates together so that a space was formed inside. Also, in Example 1, an example was shown in which an inner fin was provided as a support portion, but the support portion could also be formed by making a part of the first outer wall portion and / or the second outer wall portion of the flat tube protrude toward the other outer wall portion and joining it to the other outer wall portion via brazing.

[0152] In addition, the heat exchanger may take the following aspects (1) to (8), for example.

[0153] [1] A heat exchanger having a first flow path, a plurality of flow path forming portions arranged at intervals from each other, and second flow paths formed between the flow path forming portions, configured so that heat transfer medium in the first flow path and a heat transfer medium in the second flow path can exchange heat, wherein the flow path forming portions have: a first outer wall portion constituting a portion of an outer wall of the first flow path facing one of two second flow paths adjacent to the flow path forming portion; a second outer wall portion constituting a portion of the outer wall of the first flow path facing the other of the two second flow paths adjacent to the flow path forming portion; and a support portion arranged between both end portions in the width direction of the flow path forming portion and continuous with both the first outer wall portion and the second outer wall portion, The heat exchanger, wherein the first outer wall portion and the second outer wall portion are made of an aluminum alloy plate having a chemical composition containing Si: 1.5 mass% or more and 3.0 mass% or less, Fe: 0.05 mass% or more and 0.6 mass% or less, Mn: 0.3 mass% or more and 2.0 mass% or less, and the remainder being Al and unavoidable impurities.

[0154] [2] The heat exchanger according to [1], wherein at least one of the first outer wall portion and the second outer wall portion and the support portion are made of a common aluminum alloy plate. [3] The heat exchanger according to [1], wherein the support portion is made of an aluminum material different from the aluminum alloy plates that make up the first outer wall portion and the second outer wall portion, and the support portion is joined to the first outer wall portion and the second outer wall portion by brazing. [4] The heat exchanger according to [3], wherein the support portion is an inner fin.

[0155] [5] The heat exchanger according to any one of [1] to [4], wherein the heat exchanger has an outer fin provided in the second flow path, and the outer fin is joined to the first outer wall portion and the second outer wall portion by brazing. [6] The heat exchanger according to [5], wherein a natural electrode potential of the outer fin is lower than a natural electrode potential of the first outer wall portion, the second outer wall portion, and fillets of the brazing joints joining these outer wall portions to the outer fin.

[0156] [7] The aluminum alloy plate constituting the first outer wall portion and the second outer wall portion further contains one or more elements selected from the group consisting of Cu: 0.8% by mass or less, Zn: 6.0% by mass or less, Mg: 0.2% by mass or less, Ti: 0.3% by mass or less, V: 0.3% by mass or less, Zr: 0.3% by mass or less, Cr: 0.3% by mass or less, Bi: 0.1% by mass or less, Ni: 0.6% by mass or less, Sn: 0.3% by mass or less, In: 0.1% by mass or less, Sr: 0.1% by mass or less, Na: 0.1% by mass or less, Sb: 0.3% by mass or less, and Ca: 0.5% by mass or less. [1] to [6] The heat exchanger described in any one of [1] to [6]. [8] The aluminum alloy plate constituting the first outer wall portion and the second outer wall portion further contains Cu: 0.1 mass% or more and 0.8 mass% or less and Zn: more than 0 mass% and 1.0 mass% or less, [1] to [7]. The heat exchanger described in any one of [1] to [7].

[0157] The method for manufacturing the heat exchanger may take the following aspect [9].

[0158] [9] A method for manufacturing a heat exchanger according to any one of [1] to [8], comprising assembling components of the heat exchanger including the flow path forming portion to prepare an assembly, and heating and brazing the assembly under conditions such that the time required to reach 575°C after reaching 450°C is 4 minutes or more and 15 minutes or less, and the time required to reach 615°C after reaching 575°C is 5 minutes or more and 40 minutes or less, to obtain the heat exchanger.

[0159] The flow passage forming aluminum alloy plate may take the following forms

[10] to

[12] .

[0160]

[10] A flow path forming aluminum alloy plate used to form an outer wall of a flow path for a heat transfer medium in a heat exchanger, % or less, and optionally containing one or more elements selected from the group consisting of Cu: 0.8 mass % or less, Zn: 6.0 mass % or less, Mg: 0.2 mass % or less, Ti: 0.3 mass % or less, V: 0.3 mass % or less, Zr: 0.3 mass % or less, Cr: 0.3 mass % or less, Bi: 0.1 mass % or less, Ni: 0.6 mass % or less, Sn: 0.3 mass % or less, In: 0.1 mass % or less, Sr: 0.1 mass % or less, Na: 0.1 mass % or less, Sb: 0.3 mass % or less, and Ca: 0.5 mass % or less, with the balance being Al and unavoidable impurities.

[0161]

[11] A flow path forming aluminum alloy plate used to form an outer wall of a flow path of a heat transfer medium in a heat exchanger, comprising: Si: 1.5% by mass or more and 3.0% by mass or less; Fe: 0.05% by mass or more and 0.6% by mass or less; Mn: 0.3% by mass or more and 2.0% by mass or less; Cu: 0.1% by mass or more and 0.8% by mass or less; Zn: more than 0% by mass and 6.0% by mass or less; and further, as optional components, Mg: 0.2% by mass or less; Ti: 0.3% by mass or less; V: 0.3% by mass or less; Zr: 0.3% by mass or less; and Cr: 0.3% by mass or less. and one or more elements selected from the group consisting of Bi: 0.1% by mass or less, Ni: 0.6% by mass or less, Sn: 0.3% by mass or less, In: 0.1% by mass or less, Sr: 0.1% by mass or less, Na: 0.1% by mass or less, Sb: 0.3% by mass or less, and Ca: 0.5% by mass or less, with the balance being Al and unavoidable impurities.

[0162]

[12] The aluminum alloy plate for forming a flow channel according to

[11] , wherein the total of the Cu content and the Fe content in the aluminum alloy plate is more than 0.65 mass%.

[0163] The heat exchanger tube material may take the following aspects

[13] to

[14] .

[0164]

[13] A tube material for a heat exchanger made from the aluminum alloy plate for forming a passage according to any one of

[10] to

[12] .

[14] The tube material for a heat exchanger according to

[13] , which has a flat portion originating from a central portion in the width direction of the aluminum alloy plate and folded portions formed by folding back both end portions in the width direction of the aluminum alloy plate toward the central portion, and tips of the folded portions face the flat portion.

[0165] The heat exchanger flow path outer wall material may take the following aspects

[15] to

[16] .

[0166]

[15] A flow path outer wall material for a heat exchanger made from the aluminum alloy plate for forming a flow path according to any one of

[10] to

[12] , the material having a plurality of grooves and a connection portion connecting adjacent grooves.

[16] A flow path outer wall material for a heat exchanger made from the aluminum alloy plate for forming a flow path according to any one of

[10] to

[12] , the material having a flat plate portion and a peripheral portion provided around the flat plate portion, the peripheral portion being bent so as to protrude in one direction in the thickness direction of the flat plate portion relative to the flat plate portion.

Claims

A heat exchanger having a first flow path, a plurality of flow path forming sections arranged at intervals from each other, and a second flow path formed between the flow path forming sections, and configured so that heat transfer medium in the first flow path and a heat transfer medium in the second flow path can exchange heat, The flow path forming portion is a first outer wall portion that constitutes a portion of an outer wall of the first flow path facing one of the two second flow paths adjacent to the flow path forming portion; a second outer wall portion that constitutes a portion of an outer wall of the first flow path facing the other of the two second flow paths adjacent to the flow path forming portion; a support portion disposed between both end portions of the flow path forming portion in the width direction and continuing to both the first outer wall portion and the second outer wall portion, The heat exchanger, wherein the first outer wall portion and the second outer wall portion are made of an aluminum alloy plate having a chemical composition containing Si: 1.5 mass% or more and 3.0 mass% or less, Fe: 0.05 mass% or more and 0.6 mass% or less, Mn: 0.3 mass% or more and 2.0 mass% or less, and the remainder being Al and unavoidable impurities. 　 The heat exchanger according to claim 1 , wherein at least one of the first outer wall portion and the second outer wall portion and the support portion are formed from a common aluminum alloy plate.

2. The heat exchanger according to claim 1, wherein the support portion is made of an aluminum material different from the aluminum alloy plates constituting the first outer wall portion and the second outer wall portion, and the support portion and the first outer wall portion and the second outer wall portion are joined via brazing. 　 The heat exchanger according to claim 3 , wherein the support portion is an inner fin.

2. The heat exchanger according to claim 1, wherein the heat exchanger has an outer fin provided in the second flow path, and the outer fin is joined to the first outer wall portion and the second outer wall portion via brazing.

6. A heat exchanger according to claim 5, wherein the natural electrode potential of the outer fin is lower than the natural electrode potential of the first outer wall portion, the second outer wall portion, and the fillets of the brazed joints that join these outer wall portions to the outer fin.

2. The heat exchanger according to claim 1, wherein the aluminum alloy plates constituting the first outer wall portion and the second outer wall portion further contain one or more elements selected from the group consisting of Cu: 0.8% by mass or less, Zn: 6.0% by mass or less, Mg: 0.2% by mass or less, Ti: 0.3% by mass or less, V: 0.3% by mass or less, Zr: 0.3% by mass or less, Cr: 0.3% by mass or less, Bi: 0.1% by mass or less, Ni: 0.6% by mass or less, Sn: 0.3% by mass or less, In: 0.1% by mass or less, Sr: 0.1% by mass or less, Na: 0.1% by mass or less, Sb: 0.3% by mass or less, and Ca: 0.5% by mass or less.

2. The heat exchanger according to claim 1, wherein the aluminum alloy plate constituting the first outer wall portion and the second outer wall portion further contains Cu: 0.1 mass% or more and 0.8 mass% or less and Zn: more than 0 mass% and 1.0 mass% or less. 　 A method for manufacturing a heat exchanger according to any one of claims 1 to 8, Assembling components of the heat exchanger including the flow path forming portion to prepare an assembly; The method for manufacturing a heat exchanger includes heating and brazing the assembly under conditions such that the time required to reach 575°C after reaching 450°C is 4 minutes or more and 15 minutes or less, and the time required to reach 615°C after reaching 575°C is 5 minutes or more and 40 minutes or less, to obtain the heat exchanger. 　 A flow path forming aluminum alloy plate used to form an outer wall of a flow path for a heat transfer medium in a heat exchanger, % or less, and optionally containing one or more elements selected from the group consisting of Cu: 0.8 mass % or less, Zn: 6.0 mass % or less, Mg: 0.2 mass % or less, Ti: 0.3 mass % or less, V: 0.3 mass % or less, Zr: 0.3 mass % or less, Cr: 0.3 mass % or less, Bi: 0.1 mass % or less, Ni: 0.6 mass % or less, Sn: 0.3 mass % or less, In: 0.1 mass % or less, Sr: 0.1 mass % or less, Na: 0.1 mass % or less, Sb: 0.3 mass % or less, and Ca: 0.5 mass % or less, with the balance being Al and unavoidable impurities. 　 A flow path forming aluminum alloy plate used to form an outer wall of a flow path for a heat transfer medium in a heat exchanger, Si: 1.5 mass% or more and 3.0 mass% or less, Fe: 0.05 mass% or more and 0.6 mass% or less, Mn: 0.3 mass% or more and 2.0 mass% or less, Cu: 0.1 mass% or more and 0.8 mass% or less, Zn: 0 Contains more than 6.0 mass% by mass, and further includes optional components: Mg: 0.2 mass% or less, Ti: 0.3 mass% or less, V: 0.3 mass% or less, Zr: 0.3 mass% or less, Cr: 0.3 mass% or less. and one or more elements selected from the group consisting of Bi: 0.1% by mass or less, Ni: 0.6% by mass or less, Sn: 0.3% by mass or less, In: 0.1% by mass or less, Sr: 0.1% by mass or less, Na: 0.1% by mass or less, Sb: 0.3% by mass or less, and Ca: 0.5% by mass or less, with the balance being Al and unavoidable impurities. 　 The aluminum alloy plate for forming a flow channel according to claim 11, wherein the sum of the Cu content and the Fe content in the aluminum alloy plate is more than 0.65 mass%. 　 A tube material for a heat exchanger, which is made from the aluminum alloy plate for forming a flow passage according to any one of claims 10 to 12.

14. The heat exchanger tube material according to claim 13, wherein the tube material has a flat portion originating from a central portion in a width direction of the aluminum alloy plate, and folded portions formed by folding back both end portions in the width direction of the aluminum alloy plate toward the central portion, and a tip of the folded portion faces the flat portion. 　 A flow path outer wall material for a heat exchanger, which is made from the flow path forming aluminum alloy plate according to any one of claims 10 to 12, and has a plurality of groove portions and connection portions that connect adjacent ones of the groove portions.

13. A flow path outer wall material for a heat exchanger, which is made from the flow path forming aluminum alloy plate according to any one of claims 10 to 12, and has a flat plate portion and a peripheral portion provided around the flat plate portion, and the peripheral portion is bent so as to protrude in one direction in the thickness direction of the flat plate portion relative to the flat plate portion.

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