WO2020196763A1 - Brazing tube, method for manufacturing same, and heat exchanger - Google Patents

Abstract

This brazing tube is made from aluminum or an aluminum alloy and comprises a flat tube main body (12) with a front surface (12a), a back surface (12b), and short-side surfaces (12c), a brazing composition layer being formed on the short-side surfaces (12c), wherein: first brazing composition layers (16) are formed 5–30 µm thick on the short-side surfaces; and second brazing composition layers (17) which are 0.5–15 µm thick are formed on front-surface-side corner portions extending from the front surface (12a) to the short-side surfaces (12c), and on back-surface-side corner portions of portions extending from the back surface (12b) to the short-side surfaces (12c).

Description

Brazing tubes and their manufacturing methods and heat exchangers

The present invention relates to a brazing tube, a method for manufacturing the same, and a heat exchanger.
The present application claims priority based on Japanese Patent Application No. 2019-0582262 filed in Japan on March 26, 2019, the contents of which are incorporated herein by reference.

Aluminum alloy heat exchangers are known in which flat multi-hole pipes, fins and header pipes are the main components, and these are brazed to form the main components.
Then, in order to manufacture this kind of heat exchanger, a powder brazing composition which is a mixture of Si powder for brazing, a fluoride-based flux, and a binder composed of a resin and a solvent is provided. Further, a method of inexpensively manufacturing a heat exchanger has been proposed by brazing a flat multi-hole tube coated with the powder brazing composition on the front and back surfaces and a fin and a header pipe. (See, for example, Patent Document 1 and Patent Document 2).

Japanese Patent Application Laid-Open No. 7-227695 (A) Japanese Patent Application Laid-Open No. 2004-330233 (A)

By using the powder brazing composition and heat exchanger described in Patent Document 1 and Patent Document 2, the brazed joint between the tube made of the flat multi-hole tube and the fin does not cause selective corrosion and is reliable. A heat exchanger with high patentability and high industrial practicality has been obtained.
When the above-mentioned powder brazing composition is applied to a flat multi-hole tube, the powder brazing composition is applied to the front surface or the back surface because the portion of the flat multi-hole tube in contact with the fins is the front surface or the back surface.
By applying the powder brazing composition to the front and back surfaces of the flat multi-hole tube, some of the components contained in the powder brazing composition diffuse to the front surface side or the back surface side of the flat multi-hole tube during brazing, and the sacrificial anode layer To form. Due to the presence of this sacrificial anode layer, a sacrificial anticorrosion effect can be obtained, and selective corrosion of the brazed portion can be suppressed.

Conventionally, when a powder wax composition is applied to a flat multi-hole tube, it is generally applied to the front and back surfaces using a coating device such as a bar coater or a roll coater. This is because the portion in contact with the fins is the front and back surfaces of the flat tube, the brazing composition can be uniformly applied at the desired speed by these coating devices, and it is suitable for mass production.

By the way, heat exchangers are being further reduced in size and weight, and measures for further improving the reliability of brazed portions are required. From this point of view, when further improving the reliability of the brazed portion using the powder brazing composition is examined, since the brazing composition is not applied to the side surface side of the flat multi-hole tube, corrosion occurs on the side surface side of the flat multi-hole tube. May progress.
Unlike the flat, wide front and back sides, the side surface of the flat multi-hole tube has a curved surface and is a narrow side surface, so the brazing composition is uniformly applied to the side surface of the flat multi-hole tube. There are problems that are difficult to do.
For example, there is a problem that the brazing composition cannot be uniformly applied to a narrow side surface having a curved surface with a bar coater or a roll coater. In particular, there is a problem that it is difficult to uniformly apply the brazing composition to the corner portion which is the boundary portion between the front and back surfaces and the side surface of the flat multi-hole tube and which is also a curved surface.

Further, in the structure for joining a flat multi-hole tube and a fin, which is applied to a heat exchanger, a structure in which a flat multi-hole tube is inserted into a slit-shaped hole formed in the fin to position and braze the two is known. Has been done. In this structure, since it is necessary to insert the flat multi-hole tube into the slit-shaped hole, it is necessary to insert the flat multi-hole tube while rubbing it along the inner edge of the hole. In this case, if the brazing composition having an uneven thickness is applied to the side surface side of the flat multi-hole tube, there is a problem that the brazing composition is peeled off when the brazing composition is rubbed against the inner surface of the hole.

The present invention has been made in view of these circumstances so as to prevent the brazing composition from peeling off on the short side surface side of the flat tube body and to ensure reliable brazing property on the short side surface side of the tube body. An object of the present invention is to provide a brazed tube and a method for manufacturing the same.
An object of the present invention is to provide a brazing tube which is less likely to cause peeling of the brazing composition even when the brazing composition is inserted into the hole of the fin to form a combined structure with the fin, and to provide a method for producing the brazing tube.
An object of the present invention is to provide a heat exchanger provided with the above-mentioned brazing tube.

The invention of the present application includes the following aspects.

(1) A brazing tube made of aluminum or an aluminum alloy, which is composed of a flat tube body having a front surface, a back surface, and a short side surface and has a brazing composition layer formed on the short side surface side.
A first brazing composition layer having a thickness of 5 to 30 μm was formed on the short side surface.
A second brazing composition layer having a thickness of 0.5 to 15 μm was formed at the front surface side corner portion extending from the front surface to the short side surface and the back surface side corner portion of the portion extending from the back surface to the short side surface. Brazing tube featuring.

(2) The brazing according to (1) above, wherein the brazing composition layer contains at least one of Si powder, a Zn-containing flux, and a non-Zn-containing flux, and further contains a binder. Brazing tube.

(3) A main brazing composition layer containing one or more of Si powder, Zn-containing flux and non-Zn-containing flux, and further containing a binder was formed on the front surface and the back surface of the tube body. The brazing tube according to (1) or (2) above.

(4) The brazing tube according to any one of (1) to (3) above, wherein the main brazing composition layer contains Si powder: 1 to 5 g / m ² .

(5) The brazing tube according to any one of (1) to (4) above, wherein the main brazing composition layer contains a Zn-containing flux: 3 to 20 g / m ² .

(6) The brazing tube according to any one of (1) to (5) above, wherein the main brazing composition layer contains a non-Zn-containing flux: 1 to 10 g / m ² .

(7) The brazing tube according to any one of (1) to (6) above, wherein the main brazing composition layer contains a binder: 0.2 to 8.5 g / m ^2. ..

(8) The brazing tube according to any one of (1) to (7) above, wherein the tube body is composed of an extruded multi-hole tube having a plurality of flow paths inside the tube body.

(9) A brazed liquid composition is sprayed onto a flat tube body having a front surface, a back surface, and a short side surface from an air spray device installed so as to face the short side surface, and the thickness is 5 to 5 to the short side surface. A 30 μm first brazing composition layer is formed, and a thickness of 0.5 to 15 μm is formed on the front surface side corner portion extending from the front surface to the short side surface and the back surface side corner portion of the portion extending from the back surface to the short side surface. A method for producing a brazing tube, which comprises forming a second brazing composition layer of the above.

(10) The brazing liquid composition according to (9) above, wherein the brazing liquid composition contains at least one of Si powder, a Zn-containing flux, and a non-Zn-containing flux, and further contains a binder and a solvent. How to make a brazing tube.

(11) The brazing according to (9) or (10) above, wherein a main brazing composition layer containing Si powder: 1 to 5 g / m ² is formed on the front surface and the back surface of the tube body. How to make a brazing tube.

(12) Any of the above (9) to (11), wherein a main brazing composition layer containing Zn-containing flux: 3 to 20 g / m ² is formed on the front surface and the back surface of the tube body. The method for manufacturing a brazing tube according to one.

(13) Any of the above (9) to (12), wherein a main brazing composition layer containing a non-Zn-containing flux: 1 to 10 g / m ² is formed on the front surface and the back surface of the tube body. The method for manufacturing a brazing tube according to one.

(14) The above (9) to (13), wherein a main brazing composition layer containing 0.2 to 8.5 g / m ² is formed on the front surface and the back surface of the tube body. The method for manufacturing a brazing tube according to any one of them.

(15) The brazing tube according to any one of (1) to (7) above and a fin having a long hole through which the tube is inserted are provided, and the tube is inserted into the long hole. A heat exchanger in which a tube and the fins are brazed, wherein the tube and the fins are brazed by a fillet which is a melt-solidified product of the brazing composition layer. ..

If the brazing tube according to this embodiment is used, it is possible to prevent the brazing composition from peeling off on the short side surface side of the flat tube body and ensure reliable brazing property on the short side surface side of the tube body. The present embodiment provides a brazing tube that prevents the brazing composition from peeling and enables reliable brazing even when the brazing composition is inserted into the hole of the fin to form a combined structure with the fin. it can.

The brazing tube according to this embodiment adopts a structure in which a brazing composition layer having a suitable thickness is provided on each of the corner portion and the short side surface, which are the boundary portions between the front and back surfaces and the short side surface. As a result, peeling of the brazing composition at the time of assembling the fin and the flat tube can be prevented, and reliable brazing can be realized at the corner portion and the short side surface side. Further, it is possible to provide a brazed structure having excellent quality of the brazed portion, which does not cause the fins to fall even when the tube body is bent and used.
If the brazing tube is provided with a brazing composition layer having a suitable thickness as described above, and the brazing heat exchanger has a high quality of the brazing part, the tube body is inserted into the insertion hole of the fin. It is possible to provide a heat exchanger in which the fins are less likely to be deformed even when the fitted structure is used, and the fins are less likely to fall even when the tube is bent and used.

It is sectional drawing of the brazing tube of 1st Embodiment which concerns on this embodiment. It is a perspective view which shows an example of the heat exchanger in which fins are brazed to the tube shown in FIG. It is a partial cross-sectional view which shows the joint part of a tube and a fin in the same heat exchanger. It is a partial cross-sectional view which shows the state before brazing in the heat exchanger shown in FIG. It is a partial cross-sectional view which shows the state after brazing in the heat exchanger shown in FIG. It is explanatory drawing which shows an example of the state in which the tube which does not provide a brazing composition layer in a corner part is inserted into the hole part of a fin in the case of assembling the heat exchanger shown in FIG. FIG. 5 is an explanatory view showing an example of a state in which a tube having a brazing composition layer at a corner portion is inserted into a hole portion of a fin when the heat exchanger shown in FIG. 2 is assembled. It is explanatory drawing which shows the state which the brazing composition is applied to the brazing tube shown in FIG. 1 by an air spray device. It is a graph which shows an example of the friction which occurs when the tube is inserted into the hole of a fin in the state shown in FIG. It is a graph which shows an example of the friction which occurs when the tube is inserted into the hole of a fin in the state shown in FIG. It is a photograph which shows an example of the application state of the brazing composition applied to the short side surface side of a flat multi-hole tube by an air spray device.

Hereinafter, an example of the embodiment of the present invention will be described in detail based on the attached drawings. In addition, in the drawings used in the following description, in order to make the features easy to understand, the featured parts may be enlarged for convenience, and the dimensional ratio of each component may be the same as that of the actual tube or heat exchanger. Not necessarily the same.

"First embodiment"
FIG. 1 shows a cross-sectional structure of a flat tube 22 applied to the heat exchanger 11 shown in FIGS. 2 and 3, and the tube 22 is extruded formed by extruding aluminum or an aluminum alloy. It is made of a tube body 12 which is a material.
The heat exchanger 11 of the first embodiment is used as a heat exchanger for indoor / outdoor units of a room air conditioner, an outdoor unit for HVAC (Heating Ventilating Air Conditioning), a heat exchanger for automobiles, and the like. It is an all-aluminum heat exchanger.

The tube 22 shown in FIG. 1 shows a state before brazing, and shows a state in which the brazing composition layer is coated on the outer peripheral surface of the horizontally installed tube main body 12.
The tube body 12 has a plurality of partition walls that partition the inside of the tube body 12 into a plurality of flow paths 12D, which are short side walls 12C and 12C in which the wide front wall 12A, the back wall 12B, and the left and right ends thereof are individually connected. It is composed of 12E. In this example, the plurality of flow paths 12D are all formed in a rectangular similar cross-sectional shape, and in the example shown in FIG. 1, 26 flow paths 12D are formed in the tube body.
The tube body 12 shown in FIG. 1 is an example, and the width, thickness, flatness (ratio of width and thickness) of each part, and the shape and number of flow paths 12D can all be arbitrarily set. Can be done.

In other words, the tube body 12 is formed in a flat shape having a wide flat front surface (upper surface) 12a and a back surface (lower surface) 12b, and flat short side surfaces 12c and 12c that individually connect both end sides thereof. ing. Further, in the tube main body 12, a corner portion 12f formed in an arc shape with a predetermined curvature is formed in a portion extending from the width direction end portion of the front surface 12a to the short side surface 12c, and the short side surface 12c is formed from the width direction end portion of the back surface 12b. A corner portion 12g formed in an arc shape with a predetermined curvature is also formed in the portion leading to. The portions of the short side surface 12c except for the upper and lower corner portions 12f and 12g are formed in a plane shape facing the front surface 12a and the back surface 12b at a substantially right angle.
The shape of the short side surface 12c is not particularly limited, and may be a curved surface or an inclined surface.

In the tube body 12 shown in FIG. 1, a main brazing composition layer 15 composed of a coating film of a brazing composition having a composition described later is formed on the front surface 12a and the back surface 12b. Further, in the tube body 12, a first brazing composition layer 16 having a composition described later is formed on the outer side of the short side surface 12c, and a second brazing composition having a composition described later is formed on the outer side of the corner portions 12f and 12g. The composition layer 17 is formed.
In the present embodiment, the main brazing composition layer 15, the first brazing composition layer 16 and the second brazing composition layer 17 are composed of brazing compositions having the same composition, which will be described later, and their coating amounts and thicknesses. Is different.

FIG. 2 shows the overall structure of the heat exchanger 11 formed by brazing the plurality of tubes 22 shown in FIG. 1 to the header tube 14 and brazing the plurality of tubes 22 to the fins 13. Shown.
As shown in FIG. 2, the heat exchanger 11 is horizontally arranged between a pair of header pipes 14 arranged vertically separated from each other on the left and right sides and vertically spaced from each other between the pair of header pipes 14. In addition, a plurality of tubes 22 (tube body 12) joined at substantially right angles to the header tube 14 and a plurality of tubes brazed to the front surface 12a or the back surface 12b of the tube body 12 to dissipate heat to the outside air. It is equipped with fins 13.

A supply pipe 18A for supplying a refrigerant to the tube 22 is connected to the upper end of one of the pair of left and right header pipes 14 via the header pipe 14. A recovery pipe 18B for recovering the refrigerant via the tube 22 is connected to the lower end of the other header pipe 14. The tube 22, fin 13, header pipe 14, supply pipe 18A, and recovery pipe 18B are all made of aluminum or an aluminum alloy.

FIG. 3 is a partial cross-sectional view of the heat exchanger 11 having a cross section taken along a plane orthogonal to the length direction of the tube 22. As shown in FIG. 3, a plurality of (26 in this embodiment) refrigerant flow paths 12D arranged along the width direction are formed inside the tube main body 12 constituting the tube 22. Further, as shown in FIG. 3, a plurality of slit-shaped holes 19 having a shape corresponding to the cross-sectional shape of the tube 22 are formed horizontally in the fins 13 at predetermined intervals in the vertical direction. As shown in FIG. 3, these hole portions 19 are formed from the left end portion to the vicinity of the right end portion of the fin 13, and the innermost portion of the hole portion 19 is located slightly in front of the right end portion of the fin 13. ..

A tube 22 is fitted into each of these holes 19, and each tube 22 is fixed to a plurality of fins 13 by brazing. The length of the hole 19 formed in the fin 13 (horizontal length shown in FIG. 3) is slightly shorter than the width of the fin 13, and the short side surface of the tube 22 inserted into the hole 19 on one side in the width direction. 12c is inserted to the innermost part of the hole 19 and brazed.

4 and 5 are partial cross-sectional views taken along the length direction of the tube 22 in the heat exchanger 11 shown in FIGS. 2 and 3, and FIG. 4 shows a state before brazing. , FIG. 5 shows the state after brazing. A plurality of fins 13 are arranged in parallel along the length direction of the tube 22 (along the left-right direction of FIGS. 4 and 5), and the tube 22 is inserted into each hole 19.
The plurality of fins 13 are arranged in parallel with each other at regular intervals. The fin 13 has a bent portion 20 that is bent to one side in the thickness direction of the fin 13 along the peripheral edge portion of the hole portion 19. The bent portion 20 is formed by a processing method such as burring.

As shown in FIG. 5, the tube 22 and the fin 13 are arranged so that the tube 22 skewers and penetrates a plurality of fins 13 arranged at regular intervals, and the fin 13 and the tube 22 are individually fixed by brazing.
In the state before brazing shown in FIG. 4, the gap between the bent portion 20 formed in the hole 19 of the fin 13 and the front surface or the back surface of the tube 22 is formed to be about 10 μm or less. If this gap is too large, the amount of wraparound of the melted brazing in the brazing step described later is insufficient, which may cause poor brazing.

As shown in FIG. 3, the fin 13 of the present embodiment has the tube 22 penetrated through the hole portion 19, but instead of the hole portion 19, it has a slit shape having a horizontal length that does not reach both ends in the width direction of the fin 13. The through holes may be provided, and the tube 22 may be passed through these through holes. In the case of this configuration, in comparison with the state shown in FIG. 3, the tube 22 exists only inside the through hole, and one end side of the tube 22 in the width direction does not protrude to the outside of the fin 13.
As described above, the penetrating position of the tube 22 with respect to the fin 13 is not particularly limited, and any joint position or shape that can secure good thermal conductivity by brazing the fin 13 and the tube 22 may be used.

Hereinafter, the main components of the heat exchanger 11 will be described in more detail.
<< Fins and their constituent materials >>
As shown enlarged in FIGS. 4 and 5, the fin 13 has a plate-shaped base material 3 and a hydrophilic film 1 coated on the first surface 3a and the second surface 3b of the base material 3. Is preferable.
The base material 3 of the fin 13 is made of a pure aluminum alloy such as JIS1050 or an alloy mainly composed of JIS3003 aluminum alloy. Further, the base material 3 may be made of an aluminum alloy in which Zn of about 2% by mass is added to a JIS3003 series aluminum alloy.
The base material 3 of the fin 13 is formed by melting the aluminum alloy by a conventional method and passing through a hot rolling step, a cold rolling step, a pressing step and the like. The method for producing the base material 3 is not particularly limited in the present invention, and a known production method can be appropriately adopted.

<< Components of header pipe >>
The aluminum alloy constituting the header pipe 14 is preferably an aluminum alloy based on an Al—Mn system. For example, it is preferable to contain Mn: 0.05 to 1.50%, and as other elements, Cu: 0.05 to 0.8% and Zr: 0.05 to 0.15% may be contained. it can.

<< Tube configuration >>
As shown in FIG. 1, the tube 22 before brazing has a tube main body 12 and brazing composition layers 15, 16 and 17 formed on the outer peripheral surface thereof.
The tube body 12 is made of, for example, a pure aluminum alloy such as JIS1050 or an alloy mainly composed of JIS3003 aluminum alloy. As an example, Si: 0.10 to 0.60%, Fe: 0.1 to 0.6% by mass, Mn: 0.1 to 0.6% by mass, Ti: 0.005 to 0.2% by mass, Cu: It is made of an aluminum alloy having less than 0.1% by mass and the balance consisting of aluminum and unavoidable impurities, and is produced by extruding these aluminum alloys.

<< Constituent material of main brazing composition layer 15 >>
The main brazing composition layer 15 formed on the tube body 12 before brazing shown in FIGS. 1 and 4 is a coating film applied at least to the portion where the fins 3 are brazed and joined.
The main brazing composition layer 15 is, for example, Si powder: 1 to 5 g / m ² , Zn-containing flux (KZnF ₃ ): 3 to 20 g / m ² , and non-Zn-containing flux: 1 to 10 g / m ^2. It is preferable that the brazing coating film contains any one or more of the above, and further contains a binder (for example, an acrylic resin): 0.2 to 8.5 g / m ² . A brazing liquid composition is formed by blending an appropriate amount of solvent with these components.

Hereinafter, the constituent materials of the brazing composition constituting the main brazing composition layer 15 will be described.
<Si powder>
The Si powder reacts with Al constituting the tube body 12 at the time of brazing to form a wax that joins the fin 3 and the tube body 12, but the Zn-containing flux and the Si powder are melted at the time of brazing to become a brazing liquid. ..
Zn in the flux diffuses uniformly in this brazing liquid and spreads uniformly on the front surface and the back surface of the tube body 12. Since the diffusion rate of Zn in the brazing liquid, which is the liquid phase, is significantly higher than the diffusion rate in the solid phase, this causes uniform Zn diffusion on the front and back surfaces of the tube, and the Zn concentration in the surface direction of the front and back surfaces of the tube is increased. It becomes almost uniform. Looking at the diffusion from the surface of the tube body 12 in the depth direction, Si becomes eutectic with Al and lowers the melting point, so Zn diffuses to the eutectic composition on the surface of the tube body 12. Zn melt diffusion layers having a predetermined thickness are formed on the front surface side and the back surface side of the tube body 12. Since this Zn melt diffusion layer serves as a sacrificial anode layer, the corrosion resistance of the brazed portions on the front surface side and the back surface side of the tube body 12 can be improved.
In the present embodiment, the brazing composition layers 16 and 17 are also formed on the short side surface side of the tube body 12, so that Zn and Si contained in these brazing composition layers 16 and 17 are diffused. A sacrificial anode layer is also formed on the short side surface side of the tube body 12.

<Si powder coating amount: 1 to 5 g / m ² >
If the coating amount of Si powder is less than 1 g / m ² , wax formation may be insufficient, and if the coating amount exceeds 5 g / m ² , the melting amount of the tube body 12 increases and the tube body 12 The wall thickness of the is reduced, which is not preferable. Therefore, the content of the Si powder in the main brazing composition layer 15 is preferably 1 to 5 g / m ² .
<Si powder particle size: maximum particle size: D (99): 30 μm or less>
If the particle size of the Si powder is 30 μm or less in D (99), a uniform Zn melt diffusion layer can be formed, but if it exceeds 30 μm, deep erosion is locally generated and uniform Zn melt is generated. There is a risk that the diffusion layer cannot be formed. Therefore, the particle size of the Si powder is preferably 30 μm or less at the maximum particle size D (99). Note that D (99) is a particle size of grains that accumulates from small grains in terms of volume and accounts for 99% of the total. All of these values can be measured by the laser light scattering method.

<Zn-containing flux, non-Zn-containing flux>
The Zn-containing flux has the effect of forming Zn melt diffusion layers on the front surface side and the back surface side of the tube body 12 and improving pitting corrosion resistance during brazing. Further, at the time of brazing, the oxide film on the outer surface of the tube 3 is destroyed, the spread and wetting of the wax are promoted, and the brazing property is improved. Since this Zn-containing flux has a higher activity than the Zn-free flux, good brazing property can be obtained even if a relatively fine Si powder is used. As the Zn-containing flux, one or more of KZnF ₃ , ZnF ₂ , and ZnCl ₂ can be used. A non-Zn-containing flux may be added to the Zn-containing flux.

Flux of the fluoride-based flux or potassium fluoroaluminate-based way of non-Zn-containing flux is a flux mainly composed of KAlF _4, various compositions are known plus additives. Examples thereof include those having a composition of K ₃ AlF ₆ + KAlF ₄ (K _1-3 AlF _6-4 ), Cs _(x), K _(y), F _{(z), and the} like. Alternatively, a fluoride-based flux (for example, a potassium fluoroaluminate-based flux) to which a fluoride such as LiF, KF, CaF ₂ , AlF ₃ , or K ₂ SiF ₆ is added can also be used. By adding a fluoride-based flux (for example, a potassium fluoroaluminate-based flux) in addition to the Zn flux, it contributes to the improvement of brazing property.

<Flux coating amount: 3 to 20 g / m ² >
If the coating amount of the Zn-containing flux is less than 3 g / m ² , the potential difference when the heat exchanger 11 is used becomes low, and the sacrificial effect may not be exhibited. Further, since the surface oxide film of the tube body 12 is not sufficiently destroyed and removed, brazing failure may occur. On the other hand, if the coating amount exceeds 20 g / m ² , the potential difference becomes excessive, the corrosion rate increases, and the anticorrosion effect due to the presence of the Zn melt diffusion layer may be shortened. Therefore, it is preferable that the coating amount of the Zn-containing flux is 3 to 20 g / m ² . As the Zn-containing flux, KZnF ₃ can be used as an example. The above-mentioned non-Zn-containing flux can be added in addition to the Zn-containing flux.

<Binder application amount: 0.2 to 8.5 g / m ² >
The brazing composition layer 15 can contain a binder in addition to the Si powder and the Zn-containing flux. Acrylic resin can be mentioned as an example of a binder.
The binder has the function of fixing the Si powder and the Zn-containing flux necessary for forming the Zn melt diffusion layer to the front surface and the back surface of the tube 22, but if the amount of the binder applied is less than 0.2 g / m ^2, it is brazed. Occasionally, Si powder or Zn flux may fall off from the tube body 12, and a uniform Zn melt diffusion layer may not be formed. On the other hand, if the coating amount of the binder exceeds 8.5 g / m ² , the brazing property may be lowered due to the binder residue, and a uniform Zn melt diffusion layer may not be formed. Therefore, the amount of the binder applied is preferably 0.2 to 8.5 g / m ² . The binder is usually transpired by heating during brazing.

The method for forming the brazing composition layer 15 composed of Si powder, flux and binder is not particularly limited in this embodiment, and is not particularly limited in this embodiment, and is a spray method, a shower method, a flow coater method, a bar coater method, a roll coater method, and a brush. It can be carried out by an appropriate method such as a coating method, a dipping method, or an electrostatic coating method.

<< Constituent materials for the first and second brazing composition layers >>
The first brazing composition layer 16 and the second brazing composition layer 17 formed on the side surface side of the tube body 12 shown in FIG. 1 basically constitute the main brazing composition layer 15. It consists of the same material as the material to be used. That is, it contains any one or more of Si powder, Zn-containing flux, and non-Zn-containing flux, and further contains a binder. Alternatively, it contains any one or more of Si powder, Zn-containing flux, and non-Zn-containing flux, and further contains a binder and a solvent.
However, the first brazing composition layer 16 and the second brazing composition layer 17 are individually formed to the desired thickness as described below. The first brazing composition layer 16 is preferably formed to a thickness in the range of 5 to 30 μm. The second brazing composition layer 17 is preferably formed to a thickness in the range of 0.5 to 15 μm.

The first brazing composition layer 16 is a brazing coating film formed on the short side surface of the tube body 12. At the time of brazing, this coating film melts and solidifies, and the short side surface side of the tube body 12 is brazed and fixed to the innermost side of the hole 19 of the fin 13.
The second brazing composition layer 17 is a brazing coating film formed at a corner portion on the short side surface side of the tube body 12. At the time of brazing, this coating film melts and solidifies, and the short side corner portion of the tube body 12 is brazed and fixed to the innermost side of the hole portion 19 of the fin 13.
Without these first and second brazing composition layers 16 and 17, the fixing force for brazing and fixing the short side surface side of the tube body 12 to the fin 13 is insufficient.

For example, in response to the demand for miniaturization and compactification of the outdoor unit, a configuration is known in which a part of the heat exchanger is bent into an L-shape in a plan view and housed in the outdoor unit. When a part of the heat exchanger is bent into an L shape in a plan view in this way, if the force for brazing and fixing the short side surface side of the tube body 12 to the innermost side of the hole 19 of the fin 13 is insufficient. A part of the plurality of fins 13 may fall down at the bent portion. If the first and second brazing composition layers 16 and 17 provided on the short side surface side of the tube main body 12 are made to have a sufficient thickness, the brazing fixing force of the fins 13 can be sufficiently secured. Therefore, even when the tube body 12 is bent into an L-shape in a plan view, the tube body 12 can be bent without causing the fins to fall.
In the case of a structure in which the tube body 12 is bent into an L shape, for example, in order to prevent buckling of the tube body 12, the number of refrigerant flow paths in the tube body 12 is reduced to adopt a structure having a low flatness. ..

If the second brazing composition layer 17 is absent or too thin, the tube body 12 is inserted into the hole 19 of the fin 13, and the corner portion of the tube body 12 rubs against the opening of the hole 19. , The insertion resistance becomes large, and there is a possibility that a problem may occur when the short side surface side of the tube body 12 is inserted into the hole 19.

When assembling the heat exchanger 11 shown in FIGS. 2 and 3, it is necessary to insert eight tube bodies 12 arranged vertically as shown in FIG. 2 into all the holes 19 with a plurality of fins 13 arranged adjacent to each other. is there. Here, even if the plurality of fins 13 are aligned and precisely arranged, the holes 19 of the fins 13 may be slightly displaced vertically or horizontally due to manufacturing errors or the like.
Further, the eight tube main bodies 12 shown in FIG. 2 are precisely manufactured, all of them are uniformly formed in thickness, and all the holes for tube insertion formed in the header tube 14 are uniformly and accurately formed at accurate positions. Even if it is done, it is possible that the tube main bodies 12 arranged vertically adjacent to each other are slightly misaligned due to manufacturing errors of each part.

When the end of the tube body 12 is inserted into the hole 19 as shown in FIG. 6 that the hole 19 of the fin 13 and the end of the tube body 12 are slightly misaligned as described above, the tube body The corner portion of 12 is an insertion operation while rubbing the inner peripheral edge of the opening of the hole 19.
Here, if the fin 13 is made of aluminum or an aluminum alloy and the tube 12 is also made of aluminum or an aluminum alloy, the aluminums rub against each other.
Since the rubbing between aluminum is a rubbing with a large frictional resistance among the rubbing between metals, the fluctuation of the frictional resistance when the tube body 12 is inserted into the hole 19 becomes large, and depending on the situation, the thin fins at the time of fitting become large. There is a risk of deforming 13.
In this respect, if the brazing composition layers 17 and 17 having an appropriate thickness are provided at the corners of the tube body 12 as shown in FIG. 7, friction between the coating film and the aluminum occurs. The resistance is less than the frictional resistance of the aluminum, which enables smoother insertion work.

Therefore, it is desirable that the second brazing composition layer 17 is formed to have a thickness in the range of 0.5 to 15 μm. If the thickness of the brazing composition layer 17 is less than 0.5 μm, the effect of reducing the frictional resistance at the time of insertion is insufficient. If the thickness of the brazing composition layer 17 exceeds 15 μm, the brazing composition layer 17 is too thick at the corner portion, and when the tube body 12 is inserted into the hole portion 19, the brazing composition layer 17 is formed. There is a risk of peeling problems.

FIG. 4 shows a vertical cross section of the tube body 12 inserted into the hole 19 of the fin 13, and the main brazing composition layer 15 of the tube body 12 faces the tube body 12 of the bent portion 20 of the fin 13. It is located between the portion to be brazed (opposing surface 20a) and the tube body 12. The main brazing composition layer 15 is cooled after heating at around 600 ° C. (brazing heating) to solidify in a state of being filled between the facing surface 20a and the tube body 12, and as shown in FIG. A fillet 15A is formed in the fin 13 and the tube body 12 is joined. Further, the brazing composition layers 16 and 17 formed on the short side surface side of the tube body 12 and its corners become fillets 15A after brazing, and the short side surface of the tube body 12 is located on the innermost side of the hole 19. Join the side and the corner side.

The main brazing composition layer 15 is formed in a region in contact with the fins 13, that is, on the front surface 12a and the back surface 12b of the tube body 12. Further, Si and Zn contained in the main brazing composition layer 15 before brazing diffuse to the tube body 12 side at the brazing temperature, and the surface layer portion of the front and back surfaces of the tube body 12 contains Si and Zn. Form an anode layer.
Further, Si and Zn contained in the brazing composition layers 16 and 17 are also diffused to the short side surface side and the corner portion side of the tube body 12 at the time of brazing, and a sacrificial anode layer containing Si and Zn is provided in these portions. Form. Therefore, after brazing, a sacrificial anode layer can be formed on the entire circumference of the tube body 12.

<< Method of forming brazing composition layer >>
A method of forming the main brazing composition layer 15 on the tube body 12 and further forming the first and second brazing composition layers 16 and 17 will be described below.
The method for forming the main brazing composition layer 15 composed of Si powder, flux, and binder is not particularly limited in this embodiment. A paint obtained by adding a solvent to Si powder, a flux, and a binder to form a brazed liquid composition may be applied by the following method and dried.
The coating can be applied by an appropriate method such as a spray method, a shower method, a flow coater method, a bar coater method, a roll coater method, a brush coating method, a dipping method, or an electrostatic coating method. By these methods, the main brazing composition layer 15 can be formed in a required range on the front surface 12a and the back surface 12b of the tube body 12 with a required coating amount.
For example, the main brazing composition layer 15 can be formed on substantially the entire surface of the front surface 12a and the back surface 12b of the tube body 12.

Next, as shown in FIG. 8, an air spray type coating device 30 is installed at a position separated from the short side surface 12c of the tube body 12 by a predetermined distance, and the brazed liquid composition is applied to the short side surface 12c and the corner portions 12f and 12g. Apply by spraying.
The brazed liquid composition used here is a brazed liquid composition obtained by adding a necessary amount of solvent to the above-mentioned Si powder, Zn-containing flux (KZnF ₃ ), and binder (for example, acrylic resin). Means a thing.
Alternatively, a liquid having a viscosity desirable for an air spray method is obtained by adding a required amount of solvent to the above-mentioned Si powder, Zn-containing flux (for example, KZnF ₃ ), non-Zn-containing flux, and binder (for example, acrylic resin). It means a liquid composition with a wax.
Alternatively, it means a brazed liquid composition in which a required amount of solvent is added to the above-mentioned Si powder, a non-Zn-containing flux, and a binder (for example, an acrylic resin) to obtain a liquid having a viscosity desirable for an air spray method.

The coating device 30 shown in FIG. 8 includes a spray gun 32 having a nozzle 31 at the tip thereof, an introduction pipe 33 for supplying liquid in the middle of the flow path of the spray gun 32, and is not shown at the rear end of the spray gun 32. It is an air spray type coating device to which the air supply device of.
As shown in FIG. 8, the brazing liquid composition is spray-coated on the short side surface side of the tube body 12 by using this coating device 30, so that the first brazing composition layer 16 and the second brazing composition layer are applied. 17 can be formed. As a specific example of the coating device 30, an air spray valve coating device manufactured by Sanei Tech Co., Ltd. can be used.
The vertical position of the nozzle 31 is adjusted, the front-back position is adjusted, and the injection pressure is adjusted with respect to the short side surface 12c of the tube body 12, and the amount of coating film on the short side surface 12c and the amount of coating film on the corners 12f and 12g are within the target range. Can be adjusted to.

After that, the tube main body 12 is inserted into the holes 19 of the fins 13 which are installed in parallel, and the tube main body 12 is fitted, assembled in a state close to FIG. 2, and brazed.
Brazing is performed by performing a brazing step of heating the brazing composition layers 15, 16 and 17 to a temperature equal to or higher than the melting point, for example, 580 to 620 ° C. in a heating furnace for about several minutes. By heating, the brazing composition layers 15, 16 and 17 are melted into a brazing liquid. This brazing liquid flows into the gap between the tube body 12 and the bent portion 20 of the fin 13, and fills these gaps. Further, the wax solution described above also flows into a gap on the short side surface side of the tube body 12 fitted at the innermost position of the hole 19 to fill this gap.

Subsequently, by cooling, as shown in FIG. 5, the waxy liquid solidifies and a fillet 15A is formed. These fillets 15A join the tube body 12 and the fins 13.
In the portion where the brazing composition layers 15, 16 and 17 are melted, Si and Zn in the flux are diffused by brazing, and in addition to the front and back surfaces of the tube body 12, the Zn melt diffusion layer (sacrificial anode layer) is also provided on the short side surface side. ) Is formed.

In this form, the first and second brazing composition layers 16 and 17 are formed after the main brazing composition layer 15 is formed, but the order of forming these may be any first. These may be formed at the same time.
For example, after the long tube body 12 made of extruded material is being conveyed, the brazing composition layers 16 and 17 are formed on the short side surface side by the coating device 30, and then the main brazing composition is formed on the front and back surfaces using a bar coater or a roll coater. Layer 15 may be formed. Further, the main brazing composition layer 15 is formed on the front and back surfaces by using a bar coater or a roll coater, and the brazing composition is continuously formed on the short side surface side by the coating device 30 provided adjacent to the bar coater or the roll coater. Material layers 16 and 17 may be formed. After forming these composition layers on a long tube body 12 made of extruded material, the tube body 12 is cut to a required length to obtain a brazing tube 22 for a heat exchanger.

<< Effect >>
According to the structure of the present embodiment, the heat exchanger 11 can be configured by brazing a tube 22 having brazing composition layers 15, 16 and 17 in combination with a plurality of fins 13. In this case, the brazing composition layer 15 provided on the front and back sides of the tube body 12 can reliably braze the fins 13 on the front and back sides of the tube body 12. Moreover, the brazing composition layers 16 and 17 provided on the short side surface side of the tube body 12 can reliably braze the short side surface side of the tube body 12 to the fins 13. Therefore, the entire tube body 12 can be reliably brazed to the fins 13 with sufficient bonding strength. That is, high quality brazing joints can be made in the heat exchanger 11.
Further, when the tube body 12 is inserted into the hole 19 of the fin 13 and assembled, the brazing composition layer 17 provided at the corner of the tube body 12 relaxes the friction when rubbing the inner peripheral edge of the hole of the fin 13, and the hole is formed. The tube body 12 can be smoothly inserted into the portion 19.
Therefore, when assembling the tube 22 and the fin 13, the fin 13 can be assembled without being deformed. Further, when the tube body 12 is fitted to the hole 19 of the fin 13, the fitting work can be performed while suppressing the peeling of the brazing composition layer 17.

When brazing using the above-mentioned brazing composition layers 15, 16 and 17, Zn is applied not only to the front surface side and the back surface side of the tube 12, but also to the short side surface 12c side, the corner portion 12f side and the corner portion 12g side. It can be diffused and a sacrificial anode layer can be formed all around the tube 12. Since the portion where the sacrificial anode layer is formed proceeds to corrode not as pitting corrosion but as surface corrosion, it is possible to provide a structure in which the tube 12 is less likely to have through holes due to corrosion.
Further, by forming the sacrificial anode layer on the entire circumference of the tube body 12, it is possible to provide the heat exchanger 11 having an anticorrosive structure capable of suppressing corrosion of the brazed portion adjacent to the sacrificial anode layer.

The main brazing composition layer 15, the first brazing composition layer 16 and the second brazing composition layer 17 may contain Si powder and a Zn-containing flux.
Further, the main brazing composition layer 15, the first brazing composition layer 16 and the second brazing composition layer 17 may contain Si powder, Zn-containing flux and non-Zn-containing flux.

The main brazing composition layer 15, the first brazing composition layer 16 and the second brazing composition layer 17 may contain a non-Zn-containing flux.
The main brazing composition layer 15, the first brazing composition layer 16 and the second brazing composition layer 17 may contain a Zn-containing flux.

Further, the main brazing composition layer 15, the first brazing composition layer 16 and the second brazing composition layer 17 may contain a Zn-containing flux and a non-Zn-containing flux.

The components of the main brazing composition layer 15, the first brazing composition layer 16 and the second brazing composition layer 17 may be different from each other.
When any of the main brazing composition layer 15, the first brazing composition layer 16 and the second brazing composition layer 17 is formed as a layer containing no Si powder, a brazing sheet, a brazing rod, etc. By use, brazing material can be supplied to the joint.

The main brazing composition layer 15 may contain Si powder and a Zn-containing flux, and the first brazing composition layer 16 and the second brazing composition layer 17 may contain a Zn-containing flux.
Further, the main brazing composition layer 15 contains Si powder, Zn-containing flux and non-Zn-containing flux, and the first brazing composition layer 16 and the second brazing composition layer 17 contain Zn-containing flux and non-Zn-containing flux. It may contain a Zn-containing flux.

The main brazing composition layer 15 may contain a non-Zn-containing flux, and the first brazing composition layer 16 and the second brazing composition layer 17 may contain Si powder and a Zn-containing flux.
Further, the main brazing composition layer 15 contains a non-Zn-containing flux, and the first brazing composition layer 16 and the second brazing composition layer 17 contain Si powder, a Zn-containing flux and a non-Zn-containing flux. It may be included.

The main brazing composition layer 15 may contain a Zn-containing flux, and the first brazing composition layer 16 and the second brazing composition layer 17 may contain Si powder and a Zn-containing flux.
Further, the main brazing composition layer 15 contains a Zn-containing flux and a non-Zn-containing flux, and the first brazing composition layer 16 and the second brazing composition layer 17 contain Si powder, a Zn-containing flux and a non-Zn-containing flux. It may contain a Zn-containing flux.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.
<< Preparation of sample >>
From an aluminum alloy plate containing Si: 0.4 to 0.6% by mass, Mn: 1.0 to 2.0% by mass, Zn: 1.0 to 3.5% by mass, and the balance unavoidable impurities and Al. Ten fins (length 100 mm × width 20 mm × thickness 0.1 mm) were prepared. Slit-shaped holes (width 1.6 mm, length 18 mm) are formed in 25 rows at regular intervals in these fins, and a flat multi-hole tube (tube) described below is fitted into these holes to heat the fins. A switch mini-core body was produced.

A flat multi-hole tube made of an aluminum alloy containing Si: 0.3 to 0.5% by mass and Mn: 0.2 to 0.4% by mass and composed of unavoidable impurities and Al was prepared. This flat multi-hole tube has a width of 17 mm, a thickness of 1.5 mm, and a corner portion having a radius of curvature of 0.3 mm at the corner portion of the boundary between the front and back surfaces and the short side surface.

In Examples 1 to 10, 51 to 60 and Comparative Examples 1 to 4, 22 to 24, Si powder: 3 g / m ² , Zn-containing flux (KZnF ₃ ) was used on the front and back surfaces of the flat multi-hole tube using a bar coater. A brazing liquid composition in which 6: 6 g / m ² and an acrylic resin as a binder: 1 g / m ² were dispersed in a solvent was applied and dried at 150 ° C. for 5 minutes to form a main brazing composition layer.

In Examples 11 to 20, 61 to 70 and Comparative Examples 5 to 8, 25 to 28, Si powder: 3 g / m ² , Zn-containing flux (KZnF ₃ ) was used on the front surface and the back surface of the flat multi-hole tube using a bar coater. : 5 g / m ² , non-Zn-containing flux (K _1-3 AlF _6-4 ): 1 g / m ² , acrylic resin as a binder: 1 g / m ² is dispersed in a solvent and a brazing liquid composition is applied. , 150 ° C. for 5 minutes to form a main brazing composition layer.

In Examples 21 to 30, 71 to 90 and Comparative Examples 9 to 12, 22 to 27, a non-Zn-containing flux (K _1-3 AlF _6-4 ) was used on the front surface and the back surface of the flat multi-hole tube using a bar coater. A brazing liquid composition in which 9 g / m ² and an acrylic resin as a binder: 1 g / m ² were dispersed in a solvent was applied and dried at 150 ° C. for 5 minutes to form a main brazing composition layer.

In Examples 31 to 40, 91 to 100 and Comparative Examples 13 to 16, 37 to 40, a Zn-containing flux (KZnF ₃ ): 9 g / m ² was used as a binder on the front surface and the back surface of the flat multi-hole tube using a bar coater. A brazing liquid composition in which 1 g / m ² of the acrylic resin was dispersed in a solvent was applied and dried at 150 ° C. for 5 minutes to form a main brazing composition layer.

In Examples 41 to 50, 101 to 110 and Comparative Examples 17 to 20, 41 to 44, Zn-containing flux (KZnF ₃ ): 5 g / m ² , non-Zn was used on the front surface and the back surface of the flat multi-hole tube using a bar coater. Flux (K _1-3 AlF _6-4 ): 4 g / m ² , acrylic resin as binder: 1 g / m ² is dispersed in a solvent, and a brazed liquid composition is applied and dried at 150 ° C. for 5 minutes. The main brazing composition layer was formed.

Next, the brazing composition was sprayed and applied to the short side surface of the flat multi-hole tube using an air spray valve device manufactured by Sanei Tech Co., Ltd. as shown in FIG. At the time of application, the flat multi-hole tube may be fixed and the air spray valve device may be moved for application, or the air spray valve device may be fixed and the flat multi-hole tube may be moved for application. At this time, the flat multi-hole tube was fixed and the air spray valve device was moved for application. Further, an air spray valve device having a discharge opening diameter of 0.2 mm was used.

In Examples 1 to 10, 71 to 80, 91 to 100 and Comparative Examples 1 to 4, 29 to 32, 37 to 40, Si powder and Zn-containing flux (KZnF ₃₎ were formed on the short side surface of the flat multi-hole tube by the above method. ), Apply a brazed liquid composition in which an acrylic resin as a binder is dispersed in a solvent (mixture of 3-methoxy-3-methyl-1-butanol and isopropyl alcohol), and then dry (150 ° C. x 5 minutes). A brazing tube whose outer peripheral surface was covered with the first and second brazing composition layers was obtained.
The applied liquid composition for brazing includes 30 parts of Si powder (D (99) particle size 10 μm), 60 parts of Zn-containing flux (KZnF ₃ powder: D (50) particle size 2.0 μm), and 10 parts of acrylic resin binder. , A brazed liquid composition comprising 100 parts of a mixture of 3-methoxy-3-methyl-1-butanol as a solvent and isopropyl alcohol.

In Examples 11 to 20, 81 to 90, 101 to 110 and Comparative Examples 5 to 8, 33 to 36, 41 to 44, Si powder and Zn-containing flux (KZnF ₃₎ were formed on the short side surface of the flat multi-hole tube by the above method. ), Non-Zn-containing flux (K _1-3 AlF _6-4 ), brazed liquid composition in which an acrylic resin as a binder is dispersed in a solvent (mixture of 3-methoxy-3-methyl-1-butanol and isopropyl alcohol). After applying the material, it was dried (150 ° C. for 5 minutes) to obtain a brazing tube whose outer peripheral surface was covered with the first and second brazing composition layers.
The coated liquid composition for brazing includes 30 parts of Si powder (D (99) particle size 10 μm), 50 parts of Zn-containing flux (KZnF ₃ powder: D (50) particle size 2.0 μm), and non-Zn-containing flux (K). _1-3 AlF _6-4 powder: D (50) particle size 2.0 μm) 10 parts, acrylic resin binder 10 parts, from 100 parts of a mixture of 3-methoxy-3-methyl-1-butanol and isopropyl alcohol as a solvent It is a brazed liquid composition.

In Examples 21 to 30 and Comparative Examples 9 to 12, a non-Zn-containing flux (K _1-3 AlF _6-4 ) and an acrylic resin as a binder are used as a solvent (3) on the short side surface of the flat multi-hole tube by the above method. -The first and second brazing compositions are obtained by applying a brazing liquid composition dispersed in (a mixture of methoxy-3-methyl-1-butanol and isopropyl alcohol) and then drying (150 ° C. x 5 minutes). A brazing tube whose outer peripheral surface was covered with a layer was obtained.
The applied liquid composition for brazing was 90 parts of non-Zn-containing flux (K _1-3 AlF _6-4 powder: D (50) particle size 2.0 μm), 10 parts of acrylic resin binder, and 3-methoxy as a solvent. A brazing liquid composition comprising 100 parts of a mixture of -3-methyl-1-butanol and isopropyl alcohol.

In Examples 31 to 40, 51 to 60 and Comparative Examples 13 to 16, 21 to 24, a Zn-containing flux (KZnF ₃ ) and an acrylic resin as a binder are used as a solvent (KZnF ₃ ) on the short side surface of the flat multi-hole tube by the above method. The first and second brazing compositions are obtained by applying a brazing liquid composition dispersed in a mixture of 3-methoxy-3-methyl-1-butanol and isopropyl alcohol) and then drying (150 ° C. x 5 minutes). A brazing tube whose outer peripheral surface was covered with a material layer was obtained.
The applied liquid composition for brazing includes 90 parts of Zn-containing flux (KZnF ₃ powder: D (50) particle size 2.0 μm), 10 parts of acrylic resin binder, and 3-methoxy-3-methyl-1- as a solvent. It is a brazed liquid composition consisting of 100 parts of a mixture of butanol and isopropyl alcohol.

In Examples 41 to 50, 61 to 70 and Comparative Examples 17 to 20, 25 to 28, a Zn-containing flux (KZnF ₃ ) and a non-Zn-containing flux (K _1-3 ) were formed on the short side surface of the flat multi-hole tube by the above method. AlF _6-4 ), a brazed liquid composition in which an acrylic resin as a binder is dispersed in a solvent (mixture of 3-methoxy-3-methyl-1-butanol and isopropyl alcohol) is applied, and then dried (150 ° C. × 5). After a minute), a brazing tube whose outer peripheral surface was covered with the first and second brazing composition layers was obtained.
The applied liquid composition for brazing has 50 parts of Zn-containing flux (KZnF ₃ powder: D (50) particle size 2.0 μm) and non-Zn-containing flux (K _1-3 AlF _6-4 powder: D (50) particle size). A brazed liquid composition comprising 40 parts (2.0 μm), 10 parts of an acrylic resin binder, and 100 parts of a mixture of 3-methoxy-3-methyl-1-butanol and isopropyl alcohol as a solvent.

Tables 1 to 3 show the thickness of the coating film applied to the short side surface and the thickness of the coating film applied to the corners in Examples 1 to 50 and Comparative Examples 1 to 15.

After applying the brazing liquid composition, it is heated to 150 ° C. for 5 minutes to dry, and the solvent is volatilized to cover the outer peripheral surface with the above main brazing composition layer and the first and second brazing composition layers. I got a brazed tube.

When manufacturing a brazing tube, the thickness (μm) of the first brazing composition layer formed on the short side surface of the flat multi-hole tube by the air spray valve device and the short side surface side of the flat multi-hole tube. A plurality of brazing tubes were prepared by changing the thickness (μm) of the second brazing composition layer formed at the corner portion of the above. The thickness of each brazing composition layer was adjusted by the injection pressure of the air spray valve device, the size of the nozzle spacing from the short side surface side of the flat multi-hole tube, and the injection position.
As described above, 25 brazing tubes coated with a brazing coating film were fitted to the holes formed in the fins arranged in parallel to assemble a heat exchanger mini-core body.
This heat exchanger mini-core body was observed, the presence or absence of deformation of the fins was investigated, and the coating film peeling that occurred when the fins and the tube were fitted was investigated.

Regarding the presence or absence of fin deformation, after assembling the heat exchanger mini-core body, a sample with no deformation at all is judged as Pass A, and a sample with some fins (deformed such as bending or breaking) is judged. It was judged as rejected B.
Regarding the coating film peeling when the fins and tubes are fitted, a sample in which no peeling has occurred in the coating film is judged to be acceptable A, and a sample in which the coating film peeling can be confirmed to an area of 1 mm square or more is regarded as rejected B. It was judged.

The assembled heat exchanger mini-core body was heated to 600 ° C. for 3 minutes in a brazing furnace in a nitrogen gas atmosphere and brazed.
For the heat exchanger obtained by brazing, the central part of the tube in the length direction is bent 90 ° so as to have an L shape in a plan view, and the brazed part of the fin is separated from the tube at the bent part. It was confirmed whether or not the fins collapsed due to the above. A sample in which no fin collapse occurred was judged to be acceptable A, and a sample in which fin collapse occurred even in one place was judged to be rejected B.
The above results are summarized in Tables 1 to 6 below.

As in the samples of Examples 1 to 110 shown in the results shown in Tables 1 to 6, the thickness of the coating film composed of the brazing composition formed on the short side surface of the flat multi-hole tube is in the range of 5 to 30 μm. If so, it was found that the fins did not fall during the bending process. The samples of Comparative Examples 3, 7, 11, 15, 19, 23, 27, 31, 35, 39, and 43 are samples having a coating thickness of 3 μm for the brazing composition, but the brazing composition layer is too thin. Therefore, the brazing strength was insufficient, and the fins collapsed during bending. The samples of Comparative Examples 4, 8, 12, 16, 20, 24, 28, 32, 36, 40, and 44 are samples having a coating thickness of 32 μm for the brazing composition, but the brazing composition layer is too thick. Therefore, stress was applied to the fins during bending, which caused the fins to collapse.
It was found that the coating film on the short side corner portion of the flat multi-hole tube did not deform when the fin and the flat multi-hole tube were fitted within the range of 0.5 to 15 μm. However, as in the samples of Comparative Examples 2, 6, 10, 14, 18, 22, 26, 30, 34, 38, and 42, the coating film peels off at a coating film thickness of 17 μm, and Comparative Examples 1, 5, and 9, With a coating film thickness of 0.3 μm as in the samples of 13, 17, 21, 25, 29, 33, 37, 41, deformation of the fin occurred when the fin and the flat multi-hole tube were fitted.
From this, it can be estimated that the thickness of the coating film on the short side corner portion of the flat multi-hole tube is preferably in the range of 0.5 to 15 μm in order to prevent the coating film from peeling off and the fin deformation. ..

From these test results, the thickness of the first brazing composition layer formed on the short side surface of the flat multi-hole tube is preferably in the range of 5 to 30 μm, and the second formed on the corner portion on the short side surface side. It was found that the thickness of the brazing composition layer is preferably in the range of 0.5 to 15 μm.

FIG. 9 shows the brazing of the corner portion of the tube using a friction measuring device (manufactured by Bruker Co., Ltd., model number: UMT Tribo) and a tube in which the brazing composition layer is applied to the corner portion as shown in FIG. It is a graph which shows the result of having measured about the fluctuation state of the friction coefficient when the brazing composition layer and the aluminum alloy plate which constitutes a fin rub against each other.
FIG. 10 shows a friction measuring device (manufactured by Bruker Co., Ltd., model number: UMT Tribo), and as shown in FIG. 6, a tube in a state where the brazing composition layer is not applied to the corner portion is used for the corner portion of the tube. It is a graph which shows the result of having measured about the fluctuation state of the friction coefficient when the aluminum alloy and the aluminum alloy constituting a fin rub against each other.

In the results shown in FIG. 9, among the polygonal lines showing the three measurement results, the alternate long and short dash line indicates the coefficient of friction, the solid line indicates the vertical load, and the dotted line indicates the frictional force.
In the results shown in FIG. 10, among the polygonal lines showing the three measurement results, the solid line showing a relatively stable value shows the vertical load, and the alternate long and short dash line and the dotted line that fluctuate greatly up and down are the friction coefficient and friction force, respectively. Is shown.

As is clear from comparing the results shown in FIG. 9 with the results shown in FIG. 10, it is more frictional to fit the tube provided with the brazing composition layer at the corner portion into the hole portion of the fin as shown in FIG. It can be seen that the fitting work can be performed with little fluctuation in both the force and the coefficient of friction. That is, it can be assumed that the tube fitting work can be performed without deforming the fins.
On the other hand, from the results shown in FIG. 10, when a tube having no brazing composition layer at the corner portion is fitted into the hole portion of the fin, a large friction fluctuation occurs, so that it is impossible according to this friction fluctuation. It is considered that an operation of applying a force to fit the tube into the hole portion occurs, and in this case, it is found that there is a high possibility that the fins will be deformed.
From these comparisons, when the tube body 12 is fitted into the hole 19 of the fin 13, it is better to form the second brazing composition layer 17 at the corner portion of the tube body 12 so that the fitting work can be performed smoothly. I found out. Therefore, there is an effect that the tube main body 12 can be attached without causing deformation of the fins 13 when the tube main body 12 is fitted.

FIG. 11 is a photograph showing an example of the application state of the brazing composition applied to the short side surface side of the flat multi-hole tube by the air spray device.
As shown in FIG. 11, it can be seen that the air spray device can form a brazing composition layer that can completely cover the short side surface side and the corner portion side of the flat multi-hole tube.

According to the brazing tube of one aspect of the present invention, peeling of the brazing composition on the short side surface side of the flat tube body can be prevented, and reliable brazing property can be ensured on the short side surface side of the tube body. Further, even when the brazing composition is inserted into the hole of the fin to form a combined structure with the fin, it is possible to provide a brazing tube which makes it difficult for the brazing composition to peel off and enables reliable brazing.

11 Heat exchanger 12 Tube body 12A Surface wall 12a Surface (upper surface)
12B back wall 12b back (bottom)
12C Side wall 12c Short side 12d Corner 12D Flow path 12E Partition 13 Fin 14 Header pipe 15 Main brazing composition layer 16 First brazing composition layer 17 Second brazing composition layer 19 Holes 20 Folds Part 22 Brazing tube 30 Coating device 31 Nozzle 32 Spray gun 33 Introduction tube

Claims (15)

1. A brazing tube made of aluminum or an aluminum alloy, which comprises a flat tube body having a front surface, a back surface, and a short side surface and has a brazing composition layer formed on the short side surface side.
   A first brazing composition layer having a thickness of 5 to 30 μm was formed on the short side surface.
   A second brazing composition layer having a thickness of 0.5 to 15 μm was formed in the front surface side corner portion extending from the front surface to the short side surface and the back surface side corner portion in the portion extending from the back surface to the short side surface. A brazing tube featuring.
2. The brazing tube according to claim 1, wherein the brazing composition layer contains at least one of Si powder, a Zn-containing flux, and a non-Zn-containing flux, and further contains a binder.
3. It is characterized in that a main brazing composition layer containing any one or more of Si powder, Zn-containing flux and non-Zn-containing flux is contained on the front surface and the back surface of the tube body, and further contains a binder. The brazing tube according to any one of claims 1 and 2.
4. The brazing tube according to any one of claims 1 to 3, wherein the main brazing composition layer contains Si powder: 1 to 5 g / m ² .
5. The brazing tube according to any one of claims 1 to 4, wherein the main brazing composition layer contains a Zn-containing flux: 3 to 20 g / m ² .
6. The brazing tube according to any one of claims 1 to 5, wherein the main brazing composition layer contains a non-Zn-containing flux: 1 to 10 g / m ² .
7. The brazing tube according to any one of claims 1 to 6, wherein the main brazing composition layer contains a binder: 0.2 to 8.5 g / m ² .
8. The brazing tube according to any one of claims 1 to 7, wherein the tube body is composed of an extruded multi-hole tube having a plurality of flow paths inside the tube body.
9. A brazed liquid composition is sprayed onto a flat tube body having a front surface, a back surface, and a short side surface from an air spray device installed so as to face the short side surface, and the short side surface has a thickness of 5 to 30 μm. A second brazing composition layer having a thickness of 0.5 to 15 μm is formed on the front surface side corner portion extending from the front surface to the short side surface and the back surface side corner portion of the portion extending from the back surface to the short side surface. A method for producing a brazing tube, which comprises forming a brazing composition layer.
10. The brazing tube according to claim 9, wherein the brazing liquid composition contains at least one Si powder, a Zn-containing flux, and a non-Zn-containing flux, and further contains a binder and a solvent. Production method.
11. The method for producing a brazing tube according to claim 9 or 10, wherein a main brazing composition layer containing Si powder: 1 to 5 g / m ² is formed on the front surface and the back surface of the tube body. ..
12. The brazing according to any one of claims 9 to 11, wherein a main brazing composition layer containing Zn-containing flux: 3 to 20 g / m ² is formed on the front surface and the back surface of the tube body. How to make a brazing tube.
13. The method according to any one of claims 9 to 12, wherein a main brazing composition layer containing a non-Zn-containing flux: 1 to 10 g / m ² is formed on the front surface and the back surface of the tube body. How to make a brazing tube.
14. The binder: any one of claims 9 to 13, wherein a main brazing composition layer containing 0.2 to 8.5 g / m ² is formed on the front surface and the back surface of the tube body. How to make a brazing tube.
15. It has a brazing tube according to any one of claims 1 to 7 and a fin having a long hole through which the tube is inserted, and the tube is inserted into the long hole, and the tube and the fin are inserted. A heat exchanger that is brazed and has a tube and fins brazed by a fillet that is a melt-solidified product of the brazing composition layer.

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