JP4548829B2 - Aluminum heat exchanger - Google Patents

Description

  The present invention relates to an aluminum heat exchanger for enhancing strength and preventing pitting corrosion of a tube made of a plate material, and preventing intergranular corrosion of fins made of a plate material and brazed to the outer surface of the tube. It is suitable for use in condensers, evaporators and the like of vehicle air conditioners.

  Conventionally, in an aluminum heat exchanger used for a condenser, an evaporator, or the like of a vehicle air conditioner, it is known that the tube is formed of an extruded porous tube (see, for example, Patent Document 1).

  In this prior art, since the tube is composed of an extruded porous tube, the tube cannot be clad with a brazing material. Therefore, by applying a mixed composition of Si powder and flux that forms a eutectic alloy with Al and acts as a brazing material to the surface of the extruded porous tube, the Si powder of this mixed composition exhibits the brazing material action. Then, the tube and the fin are brazed. A typical example of the fin brazed to the tube is a corrugated fin made of a plate material bent into a wave shape.

Various aluminum heat exchangers are also known in which the tube is made of a plate material. In this case, the brazing material is clad on the plate material constituting the tube or the core material of the plate material constituting the fin, and the tube and fin are connected. I try to braze the gap.
Japanese Patent No. 3337416

  By the way, in the aluminum heat exchanger for vehicles, the thickness reduction of the structural member is requested | required for weight reduction and reduction of material cost. In order to reduce the thickness, it is effective to apply a high-strength aluminum alloy, specifically, an aluminum alloy containing a relatively high concentration of Mg.

  However, since this high-strength aluminum alloy has an increased deformation resistance as the material strength increases, the extrusion formability decreases. Accordingly, when a high-strength aluminum alloy is used as a tube material, there arises a problem that productivity of the extruded porous tube is lowered.

  As a result, when a high-strength aluminum alloy is used as a tube material, a tube made of a plate material is more advantageous for securing productivity than an extruded porous tube.

  FIG. 6 is a diagram showing the relationship between the tensile strength and the Mg addition amount of a high-strength aluminum alloy containing Mg. The horizontal axis Mg addition amount is the base alloy of the core material of the clad material. It is the addition amount with respect to Al alloy which consists of -0.5Cu-1.6Mn-1.0Si. The addition amount of each element is shown in mass%. In FIG. 6, the tensile strength is measured with a double-sided clad material in which a clad material is provided on both sides of the core material.

  As understood from FIG. 6, the tensile strength of the double-sided clad material can be improved in proportion to the increase in the amount of Mg added. However, with the addition of a relatively high concentration of Mg, the F element in the fluoride flux reacts with Mg during brazing to produce MgF2, KMgF3, and the like. These MgF2 and KMgF3 (fluorinated Mg compound) increase the melting point of the fluoride-based flux, thereby inhibiting “wax wettability” by the flux and degrading brazing.

  This will be described in more detail with reference to FIG. 7. FIG. 7A is a schematic diagram showing a gap filling test method, in which an inclined plate is inclined with respect to a horizontal plate at a predetermined angle θ, and the inclined plate is arranged. One end is brought into contact with the horizontal plate. Then, when the horizontal plate and the inclined plate are brazed, the gap filling test is to measure the filling length L of the wax filled in the gap between the horizontal plate and the inclined plate. In this test, it can be evaluated that the longer the gap filling length L, the better the brazing property.

  By the way, in the prior art, as shown in the column of the conventional product in FIG. 7B, a clad in which A4045 (Al—Si brazing material) is clad on a core material of a high strength aluminum alloy to which a relatively high concentration of Mg is added. When using this material as a horizontal plate and brazing the horizontal plate and an inclined plate made of A3003, the gap filling length L was measured by changing the amount of Mg added in the core material. ), The result indicated by the Δ mark (broken line) was obtained. In addition, the added amount of Mg on the horizontal axis in FIG. 7C is the added amount with respect to the base alloy (Al-0.5Cu-1.6Mn-1.0Si) of the core material.

  As shown by the broken line in FIG. 7 (c), it can be seen that the gap filling length L decreases as the amount of Mg added increases, and the brazing performance decreases. This decrease in brazing is because the flux action decreases due to the formation of the Mg fluoride compound.

  The gap filling length L is generally required to be at least 10 mm or more in order to ensure a level of brazing that does not hinder the product. Then, in the prior art, it is necessary to limit the upper limit value of the Mg addition amount to 0.3% by mass in order to ensure brazability. This is unavoidable, at the expense of improving the core material strength by increasing the amount of Mg added.

  In FIG. 7, the case where the brazing material is clad on the horizontal plate side has been described. However, even if the brazing material is clad on the inclined plate side, the brazing property is similarly reduced due to the generation of the Mg fluoride compound.

  Here, when a clad material in which a brazing material is clad on both sides is used as the fin material, Si in the brazing material diffuses into the fin core material and causes intergranular corrosion in the fin core material. That is, during brazing heating, a phenomenon occurs in which Si in the brazing material diffuses preferentially along the boundary portion (grain boundary) of crystal grains inside the core material. In particular, since the fin material has a small thickness of about 0.05 mm, the diffusion of Si penetrates the fin material.

  And since the Si diffusion part (grain boundary part) into this core material forms a part where the potential is electrochemically noble than the crystal part of the surrounding Al alloy, the Si diffusion part (grain boundary part) A portion where the electric potential is relatively low is formed around the periphery of. As a result, the periphery of this Si diffusion portion (grain boundary portion) is selectively corroded. This is the intergranular corrosion of the fin core material, which is a major cause of a decrease in the corrosion resistance of the fin.

  The present invention has been made in view of the above points. In an aluminum heat exchanger for brazing a tube made of a plate material and a fin made of a plate material, the corrosion resistance of both the tube and the fin is improved. The purpose is to achieve both high strength and high strength.

  Another object of the present invention is to provide an aluminum heat exchanger that is advantageous in reducing manufacturing costs.

In order to achieve the above object, in the invention according to claim 1, in the aluminum heat exchanger for brazing the tube (10) made of a plate material and the fin (12) made of the plate material,
The plate material for the tube (10) includes a core material (10b) made of a high-strength aluminum alloy containing 0.1 to 1.0% by mass of Mg, and the tube (10) among the core material (10b). ) Of the sacrificial corrosion material (10c) clad on one surface which is the outer surface of the tube (10) and the Mg diffusion prevention clad on the other surface which is the inner surface of the tube (10) among the core material (10b). A multilayer clad material having a material (10d) and a brazing material (10e) clad on the Mg diffusion preventing material (10d),
The plate material for the fin (12) is an aluminum bear material that is not clad with a brazing material,
The tube (10) and the fin (12) are brazed using a brazing powder and a fluoride flux,
The mating surface (10a) of the plate material for the tube (10) is brazed using the brazing material (10e) and a fluoride-based flux.

  According to this, the strength of the tube (10) plate is improved by adding a relatively high concentration of 0.1 to 1.0% by mass of Mg to the core (10b) of the tube (10) plate. it can.

  Here, the lower limit value (0.1% by mass) of the Mg addition amount is the minimum amount necessary for improving the strength by adding Mg. The upper limit (1.0% by mass) of the amount of added Mg is a value for suppressing deterioration in brazing properties resulting from the formation of a Mg fluoride compound due to the reaction between Mg and F of the fluoride-based flux.

  According to the present invention, since the sacrificial corrosion material (10c) is clad on the outer surface of the core material (10b), the corrosion resistance (pitting corrosion prevention effect) of the tube (10) can be improved by the sacrificial corrosion material (10c). In addition, the sacrificial corrosion material (Mg) in the core material (10b) diffuses into the brazing site between the tube (10) and the fin (12) during brazing heating and reacts with F of the fluoride-based flux ( 10c).

  Similarly, since the brazing material (10e) is clad on the inner side surface of the core material (10b) via the Mg diffusion preventing material (10d), the Mg in the core material (10b) is heated by the tube (10 ) Can be suppressed by the presence of the Mg diffusion preventing material (10d) from diffusing into the brazing portion of the mating surface (10a) and reacting with the fluoride flux F.

  Thus, it is possible to suppress the Mg in the core material (10b) from reacting with F of the fluoride-based flux at the time of brazing heating by intervening the sacrificial corrosion material (10c) and the Mg diffusion preventing material (10d). Even if the amount of Mg added in the material (10b) is increased to 1.0% by mass, the brazing property between the tube (10) and the fin (12) and the brazing property of the tube mating surface (10a) are ensured well. it can. As a result, the tube strength can be effectively improved by increasing the amount of added Mg while ensuring the brazing property to a necessary level.

  Moreover, since the tube (10) is composed of a plate material, the core material (10b) of the tube material for the tube (10) is extruded even if it is composed of a high-strength aluminum alloy containing a relatively high concentration of Mg. There is no problem such as a decrease in extrudability like a perforated tube. Therefore, the strength of the tube (10) can be improved, and at the same time, the tube (10) can be efficiently molded with high productivity.

  Further, since the tube (10) and the fin (12) are brazed using the brazing material powder, it is not necessary to clad the brazing material on any of the plate material for the tube (10) and the plate material for the fin (12). .

  For this reason, it suffices to clad only the sacrificial corrosive material (10c) on the outer surface of the plate material for the tube (10). Therefore, the sacrificial corrosive material (10c) is necessary even if the plate material for the tube (10) is thinned. The thickness can be secured to ensure the corrosion resistance (pitting corrosion prevention effect) of the tube (10). As a result, it is possible to achieve both corrosion resistance of the tube (10), weight reduction of the tube (10), and reduction of material costs.

  In addition, since the fin (12) is made of an aluminum bare material in which the brazing material is not clad, the fin (12) is made of Si, which is a brazing material component, as compared with the case where the fin (12) is made of a clad material clad with the brazing material. Diffusion to the fin material can be remarkably suppressed, thereby preventing intergranular corrosion of the fin (12).

  Also, since the tube mating surface (10a) is brazed using the brazing material (10e) clad on the inner side surface of the core material (10b), the tube mating surface (10a) is specially used for brazing. There is no need to supply a brazing material, and the tube mating surface (10a) can be easily brazed by the clad brazing material (10e) of the plate material for the tube (10) itself.

In the first aspect of the present invention, the sacrificial corrosion material (10c) of the plate material for the tube (10) is further mixed with the mixed composition (10f) obtained by mixing the brazing filler metal powder and the fluoride-based flux. ), The tube (10) and the fin (12) are brazed.

  According to this, compared with the case where a mixed composition (10f) is apply | coated to the board | plate material for fins (12), the spreading | diffusion to the fin material of a brazing filler metal component can be suppressed.

As in the invention according to claim 2 , in the aluminum heat exchanger according to claim 1 , specifically, the brazing filler metal powder may be Si powder.

As in the invention described in claim 3, in an aluminum heat exchanger according to claim 1, wherein the brazing material powder may be a powder mixture of Si powder and Al powder.

  Thus, when a mixed powder of Si powder and Al powder is used as the brazing material powder, the Si powder reacts with the Al powder during brazing to produce an Al-Si alloy (brazing material). The dissolution depth of the sacrificial corrosion material (10c) can be reduced. Therefore, it becomes easy to ensure the remaining thickness of the sacrificial corrosion material (10c) after brazing.

As in the invention according to claim 4 , in the aluminum heat exchanger according to any one of claims 1 to 3, the brazing material (10e) on the Mg diffusion preventing material (10d) is an Al-Si brazing material. A material may be used.

In invention of Claim 5 , in the aluminum heat exchanger in any one of Claims 1-4 , the said core material (10b) is 0.3-0.7 mass% Mg, 0.8 characterized in that it contains 1.8 wt% of Mn.

  According to this, by prescribing the upper limit value of the Mg addition amount to 0.7 mass%, the reaction between Mg and F of the fluoride-based flux can be further suppressed, and the brazing property can be further improved. Moreover, tube intensity | strength can be improved further by making the minimum value of Mg addition amount into 0.3 mass%, and adding Mn 0.8 mass% or more.

  In addition, the deterioration of rolling workability accompanying Mn addition can be suppressed by prescribing the upper limit of Mn addition amount to 1.8% by mass.

In the invention of claim 5, further in an aluminum heat exchanger according to claim 1, wherein the core (10b) is further and 0.7 to 1.1 wt% Si 0.5 to 1.0 mass% Fe, 0.8 mass% or less Cu, 0.02 to 0.3 mass% Zr, 0.02 to 0.3 mass% Cr, You may make it the composition which contains 1 type (s) or 2 or more types among 0.05-0.4 mass% Ti.

According to a sixth aspect of the present invention, in the aluminum heat exchanger according to any one of the first to fifth aspects, the Mg diffusion preventing material (10d) is an aluminum alloy containing no Mg, and is at least 0.00. It contains 8 to 1.8% by mass of Mn.

  According to this, the strength of the Mg diffusion preventing material (10d) can be secured by adding Mn.

According to a seventh aspect of the present invention, in the aluminum heat exchanger according to any one of the first to sixth aspects, the sacrificial corrosion material (10c) is an aluminum alloy that does not contain Mg, and is at least 0.00. It contains 8 to 1.8% by mass of Mn and 0.5 to 10.0% by mass of Zn, and has a lower potential than the core material (10b).

  According to this, the strength of the sacrificial corrosion material (10c) can be ensured by adding Mn, and the potential becomes base by adding Zn, and the sacrificial corrosion effect can be exhibited.

  In addition, the code | symbol in the bracket | parenthesis of each said means shows the correspondence with the specific means as described in embodiment mentioned later.

(First embodiment)
This embodiment is an example in which the present invention is applied to an evaporator of a vehicle air conditioner. First, an outline of an evaporator of a vehicle air conditioner will be described with reference to FIGS. 1 to 3. The tube 10 and the header tank 11 are joined by brazing in a state where both ends in the longitudinal direction of the tube 10 are communicated with the inside of the header tank 11.

  In this example, the tube 10 is formed in a passage shape having a flat cross section by bending a single aluminum plate as shown in FIG. A mating surface 10 a forming a passage-shaped coupling portion is provided at one end of the flat cross section of the tube 10.

  The header tank 11 has an elongated tank shape extending in the stacking direction of the tubes 10 (left and right direction in FIGS. 1 and 2), and a communication space for communicating both ends of the tube 10 in the longitudinal direction inside the tank shape. Constitute. As shown in FIG. 2, the header tank 11 has flat through holes 11 a into which both ends of the tube 10 in the longitudinal direction are inserted.

  Both end portions of the tube 10 in the longitudinal direction are inserted into the through hole 11a, and the header tank 11 and the tube 10 are brazed at the portion of the through hole 11a.

  Between the multiple tubes 10, fins 12 forming outer fins are arranged so as to extend in the longitudinal direction of the tubes. The fins 12 are corrugated fins formed by bending an aluminum plate into a corrugated shape, and the tops of the corrugated shapes are in contact with the outer surfaces of the tubes 10 adjacent to the left and right sides and brazed.

  In the evaporator, air is blown in the direction of the arrow A in FIG. 1 through the gap portion of the heat exchange core portion formed by the tubes 10 and the fins 12, and the blown air and the refrigerant passing through the tubes 10 Heat exchange is performed through the fins 12, the latent heat of vaporization of the refrigerant is absorbed from the blown air, and the blown air is cooled.

  Next, specific material configurations of the tube 10 and the fins 12 will be described based on FIG. 3B, FIG. 4 and FIG. As shown in FIG. 3B, the tube 10 includes a core material 10b, a sacrificial corrosion material 10c clad on one surface of the core material 10b, and an Mg diffusion preventing material 10d clad on the other surface of the core material 10b. And a brazing material 10e clad on the Mg diffusion preventing material 10d (multi-layer clad material).

  Here, the sacrificial corrosion material 10c is clad on one surface of the core material 10b which becomes the outer surface (air side surface) of the tube 10, and the Mg diffusion preventing material 10d and the brazing material 10e are included in the core material 10b. It is clad on the other surface which becomes the inner surface (surface on the refrigerant side) of the tube 10.

  FIG. 4 shows seven examples of the core material 1 to the core material 7 as specific material compositions of the core material 10 b of the tube 10. Here, the core material 1 is a comparative example, and Mg is not added. On the other hand, the core materials 2 to 7 have a material composition containing a relatively high concentration of Mg according to the present embodiment.

  FIG. 5 shows specific material composition examples of the sacrificial corrosion material 10c, the Mg diffusion preventing material 10d and the brazing material 10e, which are the outer and inner cladding materials of the tube 10, and specific material composition examples of the fins 12. ing. In addition, the addition amount of each chemical component of FIG. 4, FIG. 5 is the mass%, and the remaining Al amount contains an unavoidable impurity. 4 and 5, the symbol (−) indicates that the addition amount is 0.0% by mass, or that it is unavoidably small.

  The core material 10b of the tube 10 is a high-strength aluminum alloy containing a relatively high concentration of Mg, specifically an Al—Mn—Mg-based aluminum alloy, as shown in the core material 2 to the core material 7 in FIG. It is.

  Here, the lower limit of the amount of added Mg is 0.1% by mass or more, more preferably 0.3% by mass or more from the tensile strength characteristics of FIG. 6 in order to ensure the core material strength. On the other hand, the upper limit of the amount of Mg added is 1.0% by mass or less, more preferably 0.8% or less, so that the gap filling length L in FIG. It is good to set it as 7 mass% or less.

  Further, Mn is added to the core material 10b to improve the strength. The lower limit of the Mn addition amount is preferably 0.8% by mass or more in order to ensure the core material strength. Although the core material strength can be improved by increasing the amount of Mn added, on the other hand, the rolling processability of the core material is hindered by increasing the amount of Mn added. Therefore, in order to ensure this rolling workability, the upper limit value of the Mn addition amount is preferably 1.8% by mass or less.

  Fe is also added to the core material 10b to improve the strength. The lower limit of the amount of Fe added is preferably 0.5% by mass or more in order to ensure the core strength. On the other hand, if the amount of Fe added exceeds 1.0% by mass, the self-corrosion property of the core material 10b accompanying the addition of Fe increases, which is not preferable. Therefore, the upper limit value of the Fe addition amount is preferably 1.0% by mass or less.

  Si is also added to the core material 10b for strength improvement. The lower limit value of the Si addition amount is preferably 0.7% by mass or more in order to ensure the core material strength. However, if the amount of Si added exceeds 1.1% by mass, the corrosion resistance of the core material 10b decreases and the melting point of the core material 10b decreases, and local melting of the core material 10b tends to occur during brazing. Therefore, the upper limit value of the Si addition amount is preferably 1.1% by mass or less.

  Cu is added to improve the strength and corrosion resistance of the core material 10b. That is, the addition of Cu changes the potential of the core material 10b in a more noble direction, thereby expanding the potential difference between the core material 10b and the sacrificial corrosion material 10c and increasing the anticorrosion effect due to sacrificial corrosion. However, if the amount of Cu added exceeds 0.8% by mass, the corrosion resistance of the core material 10b decreases and the melting point of the core material 10b decreases, and local melting of the core material 10b tends to occur during brazing. Therefore, the upper limit value of the Cu addition amount is preferably 0.8% by mass or less.

  Further, Zr and Cr coarsen the crystal grain size of the core material 10b, and when Mg is added to the core material 10b, the grain boundary diffusion during brazing heating of Mg is suppressed to prevent the core material strength from being lowered. Therefore, in order to ensure the effect of preventing the strength reduction, the lower limit values of the Zr addition amount and the Cr addition amount are preferably 0.02% by mass or more.

  Further, since the above effect does not change greatly even if the addition amount of Zr and Cr is increased, the upper limit of the addition amount of Zr and the addition amount of Cr should be 0.3% by mass or less in order to reduce the material cost. .

  Further, Ti is distributed in a layered manner in a high concentration region and a low region in the thickness direction of the core material 10b. With such a layered distribution of Ti, the corrosion form of the core material 10b is layered to suppress the progress of corrosion in the thickness direction of the core material 10b.

  In order to ensure such an action of suppressing the progress of corrosion, the lower limit value of the Ti addition amount is preferably 0.05% by mass or more. Further, the upper limit value of the Ti addition amount is preferably 0.4% by mass or less in order to ensure the rolling workability of the core material 10b.

  The sacrificial corrosion material 10c forming the outer cladding layer is specifically an aluminum alloy to which 4.0% by mass of Zn is added as shown in FIG. Here, the sacrificial corrosion material 10c has a lower potential than the core material 10b due to the addition of Zn, and exhibits a sacrificial corrosion action on the core material 10b.

  Here, the lower limit of the Zn addition amount is preferably 0.5% by mass or more in order to ensure sacrificial corrosion. Further, the upper limit value of the Zn addition amount is preferably 10.0% by mass or less in order to suppress the self-corrosion property of the sacrificial corrosion material 10c.

  The reason why Mn is added to the sacrificial corrosion material 10c is to ensure strength, and the preferable range of the Mn addition amount is 0.8 to 1.8% by mass for the same reason as in the case of the core material 10b.

  The Mg diffusion preventing material 10d forming the inner cladding layer is an aluminum alloy to which no Mg is added, and at least Mn is added to ensure strength. A preferable range of the Mn addition amount is 0.8 to 1.8% by mass for the same reason as in the case of the core material 10b.

  The brazing material 10e forming the inner cladding layer is a general Al—Si alloy, and Si forms a eutectic alloy with Al, so that the melting point of the brazing material 10e is higher than the melting point of the core material 10b. The temperature becomes lower.

  In the present embodiment, the plate thickness t of the plate material for the tube 10, that is, the total plate thickness t of the multilayer clad material including the outer and inner clad layers 10c, 10d, and 10e (see FIG. 3B) is 0. The clad rate of the sacrificial corrosion material 10c that is the outer clad layer is 20%, and the total clad rate of the Mg diffusion preventing material 10d and the brazing material 10e that are the inner clad layers is also 20%. Therefore, the thickness of the sacrificial corrosion material 10c is 0.04 mm, and the total thickness of the Mg diffusion preventing material 10d and the brazing material 10e is also 0.04 mm.

  On the other hand, the plate material constituting the fin 12 is made of an aluminum bare material that is not clad with a brazing material. The aluminum bare material for fins is an Al—Mn-based aluminum alloy to which Mg is not added as shown in FIG. The reason why 2.0 mass% of Zn is added to the fin aluminum bare material is that the fin 12 itself exerts a sacrificial corrosion effect on the tube 10. In addition, the plate | board thickness (plate | board thickness of the aluminum bear material for fins) of the fin 12 is 0.05 mm.

  A mixed composition 10f of a brazing material powder and a flux for brazing the tube 10 and the fins 12 is applied to the outer surface of the tube 10 plate material, that is, the surface of the clad layer of the sacrificial corrosion material 10c. . Here, the brazing material powder is specifically Si powder. Si powder may be used alone as the brazing material powder, but a mixed powder of Si powder and Al powder may be used as the brazing material powder.

  Further, the flux is a fluoride-based flux (non-corrosive flux), and more specifically, any one of KAlF4, K3AlF6, K2AlF5, AlF3, KZnF3, CsAlF and CsKAlF, or a plurality of them. Use a mixture.

  Further, a flux 10g is applied to the inner surface of the plate material for the tube 10, that is, the surface of the clad layer of the brazing material 10e. This flux 10g is the same as the flux of the mixed composition 10f (fluoride-based flux).

  Since the header tank 11 is a strength member that supports the tube 10 and the like, the thickness thereof is sufficiently larger than the tube 10 and the fins 12, for example, 0.6 mm. The header tank 11 is composed of a double-sided clad material in which a brazing material is clad on both sides of the core material.

  Next, the manufacturing method of the aluminum heat exchanger according to the present embodiment will be described. The manufacturing method according to the present embodiment includes (1) an application process of the mixed composition 10f, flux 10g and the like to the heat exchanger component parts and a molding process of each part, and (2) an assembly process of the heat exchanger component parts. (3) It is roughly divided into a brazing process.

  First, the application process of flux and the like of each component and the molding process of each component will be described. The plate material for the tube 10 includes a core material 10b, a sacrificial corrosion material 10c as an outer cladding layer, and Mg diffusion as an inner cladding layer. When the multilayer clad material is in the form of a flat plate, the Si powder for the brazing material and the fluoride system are formed on the outer surface (the surface of the sacrificial corrosion material 10c). The mixed composition 10f with the flux is applied.

  Here, when applying the mixed composition 10f, a solution having an appropriate viscosity in which Si powder and flux powder are dissolved in a solvent containing a resin binder is prepared. It apply | coats to the outer surface of the board | plate material for tubes 10 by well-known methods, such as a coating method and a spraying method. Here, the solution includes a paste.

  Further, a flux 10g is applied to the inner side surface of the tube 10 plate (the surface of the brazing material 10e). When applying the flux 10g, specifically, the inner surface of the plate material for the tube 10 is prepared by using the above known method to prepare a solution of a flux 10g having an appropriate viscosity obtained by dissolving the flux powder in a solvent containing a resin binder. What is necessary is just to apply | coat to.

  Thus, after apply | coating the mixed composition 10f and the flux 10g, the board | plate material for tubes 10 is bend-molded so that it may become a cross-sectional passage shape as shown to Fig.3 (a), and the bending end part may be carried out. The mating surface 10a is formed.

  The plate material for the fin 12 is formed by corrugating fins by bending the above-described aluminum bear material into a wave shape as it is.

  The plate material for the header tank 11 is formed by forming the aforementioned clad material into the tank shape shown in FIG. A flux (specifically, a fluoride-based flux) is also applied to the header tank 11 plate by the known method.

  Next, the assembly process will be described. The parts such as the heat exchanger tube 10, header tank 11, fin 12 and the like are assembled in the predetermined structure shown in FIGS. 1 and 2, and the assembly (temporary assembly state) ) Is fastened and held by a jig such as a wire.

  Next, a brazing process will be described. The assembly is held by a jig, is carried into a brazing heating furnace, and the assembly is heated to a brazing temperature, whereby a heat exchanger is obtained. The parts are brazed together.

  Here, the Si powder applied to the outer surface of the tube 10 (the surface of the sacrificial corrosion material 10c) reacts with Al of the sacrificial corrosion material 10c to form a eutectic alloy and melt at the brazing temperature. It plays a role as a material. That is, the tube 10 and the fin 12 can be brazed using the Si powder of the mixed composition 10f.

  Further, the mating surfaces of the tubes 10 can be brazed with a brazing material 10 f clad on the inner surface of the tube 10.

  Moreover, it can braze between the header tank 11 and the both ends of the tube 10 using the brazing material clad by the header tank 11 and Si powder of the mixed composition 10f on the tube 10 side.

  In this brazing process, the flux powder of the mixed composition 10f applied to the outer surface of the tube 10 (the surface of the sacrificial corrosion material 10c), the flux 10f applied to the inner surface of the tube 10, and the header tank 11 are applied. The soldered flux becomes a molten state (liquid state) at the brazing temperature and spreads uniformly on the joint surface between the parts.

By this molten flux component, the oxide film on the surface of the aluminum material of each part is reduced, and the wettability between the molten brazing material and the surface of the aluminum base material is improved. The brazing furnace is maintained in an inert gas atmosphere such as N ₂ gas to prevent reoxidation of the aluminum material surface. By the above, the favorable brazing property between each component is ensured.

  Moreover, since the flux of each part is a fluoride-based flux, and this fluoride-based flux is non-corrosive to the aluminum material, the water washing process for removing flux residue after brazing is abolished. Or it can be simplified.

  By the way, according to the present embodiment, a relatively high concentration of Mg is added to the core material 10b of the multilayer clad material, which is a plate material for the tube 10, in order to improve the strength of the core material. It is possible to satisfactorily suppress Mg from reacting with the fluoride flux of the outer mixed composition 10f and F of the inner flux 10f.

  That is, since the outer surface of the tube core material 10b is clad with the sacrificial corrosion material 10c to which no Mg is added, even if Mg in the core material 10b diffuses during brazing heating, the diffusion of the Mg is sacrificed. It can suppress substantially within the plate | board thickness range of the foodstuff 10c, and can suppress that Mg reacts with F of the fluoride flux of the outer side mixed composition 10f directly.

  Similarly, since the Mg diffusion preventing material 10d not added with Mg is also clad on the inner side surface of the tube core material 10b, the diffusion of Mg in the core material 10b during brazing heating is reduced to the plate of the Mg diffusion preventing material 10d. It is possible to prevent Mg from reacting directly with F of the inner flux (fluoride flux) 10f by substantially suppressing the thickness within the range.

  As described above, since the formation of the Mg fluoride compound can be suppressed during brazing heating, it is possible to suppress a decrease in brazing property due to the generation of the Mg fluoride compound.

  In addition, the example of this invention of the horizontal plate of FIG.7 (b) is the core material 10b which consists of an Al-Mn-Mg type alloy which added comparatively high concentration Mg, and the said Al-Mn which does not add Mg. The example of a combination with the sacrificial corrosion material 10 which consists of a -Zn-Si type alloy is shown.

  According to this combination example, as shown in FIG. 7 (c), even if the amount of Mg added to the core material 10b is increased to 1.0% by mass, the gap filling length L can be 10 mm, which is necessary. Brazing ability can be secured. In other words, in the present invention, even if the Mg addition amount is increased to 1.0% by mass, brazing properties equivalent to Mg addition amount = 0.3% by mass in the prior art can be secured.

  Although not shown in FIG. 7B, the amount of Mg added to the core material 10b is 1. even in the configuration in which the inner surface of the tube core material 10b is clad with the brazing filler metal 10f via the Mg diffusion preventing material 10d. Even if it increases to 0 mass%, it is confirmed that the gap filling length L can be 10 mm, and the necessary brazing properties can be obtained.

  As described above, the strength of the tube plate material is improved by adding a relatively high concentration of Mg to the core material 10b, and at the same time, the reaction between Mg and F of the fluoride flux is suppressed, and the necessary brazing property is achieved. It can be secured. Incidentally, when the Mg addition amount is increased to 1.0 mass%, the tensile strength of the plate material (multilayer clad material) for the tube 10 can be improved to about 330 MPa as can be seen from FIG.

  As shown in the rightmost column of FIG. 4, the tensile strength of the multilayer clad material having the core material 1 (comparative example) to which Mg is not added is a low value of 167 MPa. In contrast, the tensile strength of the multilayer clad material having the core material 2 to the core material 7 to which a relatively high concentration of Mg is added according to the present embodiment is in the range of 200 to 300 MPa, which is significantly higher than that of the core material 1. The value is high.

  In this embodiment, since the tube 10 and the fin 12 are brazed using the brazing powder of the outer mixed composition 10f, the brazing material is clad on both the plate material for the tube 10 and the plate material for the fin 12. There is no need.

  Therefore, it suffices to clad only the sacrificial corrosive material 10c on the outer surface of the plate material for the tube 10, and therefore the necessary thickness of the sacrificial corrosive material 10c can be sufficiently secured even if the plate material for the tube 10 is thinned.

  Therefore, the Si powder, which is the brazing filler metal powder of the outer mixed composition 10f, reacts with Al in the sacrificial corrosion material 10c during brazing heating to produce an Al—Si alloy, and when the role of the brazing filler metal, Even if melting holes occur in the sacrificial corrosion material 10c and the plate thickness of the sacrificial corrosion material 10c decreases, the remaining plate thickness after brazing of the sacrificial corrosion material 10c is set to a size necessary for ensuring tube corrosion resistance. it can.

  Thereby, the corrosion resistance (tube pitting prevention effect) of the tube 10 can be sufficiently ensured. As a result, it is possible to achieve both corrosion resistance of the tube 10, weight reduction of the tube 10, and reduction of material cost.

  Note that a mixed powder of Si powder and Al powder may be used as the brazing filler metal powder of the outer mixed composition 10f. In this case, the Si powder reacts with the Al powder during brazing heating, and an Al—Si based alloy ( Therefore, the depth of dissolution of the sacrificial corrosion material 10c by the Si powder brazing can be reduced. Therefore, there is an advantage that the remaining thickness of the sacrificial corrosion material 10c after brazing can be easily secured.

  Further, since the fin 12 is made of an aluminum bare material in which the brazing material is not clad, compared to the case where the fin 12 is made of a clad material clad with the brazing material, the fin material of Si, which is a brazing material component, is used. Diffusion can be remarkably suppressed, whereby the intergranular corrosion of the fins 12 can be prevented.

  Further, since the tube 10 is made of a plate material, even if the core material 10b of the tube 10 plate material is made of a high-strength aluminum alloy containing a relatively high concentration of Mg, it is extruded like an extruded porous tube. There is no problem of deterioration of moldability. Therefore, the strength of the tube 10 can be improved, and at the same time, the tube 10 can be efficiently molded with high productivity.

  Further, since the mating surface 10a of the tube 10 can be brazed by the brazing material 10e clad on the inner surface of the core material 10b of the tube 10 plate material, the brazing material is specially supplied from the other for brazing the mating surface 10a. Without this, the mating surface 10a can be easily brazed with the brazing material 10e of the tube 10 itself.

(Other embodiments)
In the above embodiment, when the tube 10 is formed of a plate material, the case where one plate material is bent to form a flat cross-sectional passage shape has been described. However, the cross section of the tube 10 is formed by bonding two plate materials together. A flat passage shape may be formed.

  The present invention is not limited to aluminum heat exchangers for vehicle air conditioners, and can be widely applied to aluminum heat exchangers for various applications.

It is a perspective view of the evaporator for vehicle air conditioning to which this invention is applied. It is a typical schematic fracture | rupture perspective view of a part of FIG. (A) is the fracture | rupture perspective view of the tube in one Embodiment of this invention, (b) is sectional drawing of a tube material. It is a chart which illustrates the concrete material composition of the core material for tubes in one embodiment of the present invention. It is a chart which illustrates the concrete material composition of the tube clad layer and fin material in one embodiment of the present invention. It is a graph which shows the relationship between the tensile strength of the cladding material for tubes, and the amount of Mg addition to a core material. (A) is a schematic explanatory diagram of the gap filling test, (b) is an explanatory diagram of a horizontal plate used in the gap filling test of (a), (c) is a relationship between the gap filling length and the amount of Mg added to the core material. It is a graph to show.

Explanation of symbols

10 ... tube, 10a ... mating surface, 10b ... core material, 10c ... sacrificial corrosion material,
10d: Mg diffusion preventing material, 10e: brazing material,
10f: a mixed composition of brazing filler metal powder and flux, 12 ... fins.

Claims (7)

In the aluminum heat exchanger for brazing the tube (10) composed of a plate material and the fin (12) composed of the plate material, the plate material for the tube (10) is 0.1 to 1.0. A core material (10b) made of a high-strength aluminum alloy containing Mg in mass%, and a sacrificial corrosion material clad on one surface of the core material (10b), which is the outer surface of the tube (10) ( 10c), Mg diffusion prevention material (10d) clad on the other surface of the tube (10) among the core material (10b), and cladding on the Mg diffusion prevention material (10d) And a plate material for the fin (12) is an aluminum bare material not clad with the brazing material, and the tube (10) and the fin (12). It is brazed with the brazing material powder and a fluoride based flux, the brazing material powder and the fluoride-based mixed composition obtained by mixing a flux (10f), among plate of the tube (10) for The tube (10) and the fin (12) are brazed by applying to the surface of the sacrificial corrosion material (10c), and the mating surface (10a) of the plate material for the tube (10) is An aluminum heat exchanger characterized by being brazed using the brazing material (10e) and a fluoride-based flux. The aluminum heat exchanger according to claim 1 , wherein the brazing filler metal powder is Si powder. The aluminum heat exchanger according to claim 1 , wherein the brazing filler metal powder is a mixed powder of Si powder and Al powder. The aluminum heat exchanger according to any one of claims 1 to 3, wherein the brazing material (10e) on the Mg diffusion preventing material (10d) is an Al-Si based brazing material. The core member (10b) has a 0.3 to 0.7 mass% of Mg, containing 0.8-1.8 mass% of Mn, further and 0.7 to 1.1 wt% Si 0.5 to 1.0 mass% Fe, 0.8 mass% or less Cu, 0.02 to 0.3 mass% Zr, 0.02 to 0.3 mass% Cr, The aluminum heat exchanger according to any one of claims 1 to 4, wherein the aluminum heat exchanger contains one or more of 0.05 to 0.4 mass% of Ti, and is composed of the balance Al and impurities . . The Mg diffusion prevention member (10d) is an aluminum alloy containing no Mg, any of claims 1 to 5, characterized in that it contains at least 0.8-1.8% by weight of Mn aluminum heat exchanger according to any. The sacrificial corrosive material (10c) is an aluminum alloy not containing Mg, and contains at least 0.8 to 1.8% by mass of Mn and 0.5 to 10.0% by mass of Zn. The aluminum heat exchanger according to any one of claims 1 to 6, wherein the potential is lower than that of the material (10b).

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