JP2001304788A - Heat exchanger having excellent brazing property - Google Patents

Abstract

PROBLEM TO BE SOLVED: To raise heat exchanging performance by ensuring brazing between a header pipe and a tube and preventing leakage of heating medium, in a heat exchanger consisting mainly of the heater pipe, the tube and a fin. SOLUTION: The header pipe and the tube are joined with a wax material by providing outwardly opening cone-shaped grooves to both the outside and the inside of a slit of the header pipe, into which the tube is to be inserted. An appropriate groove angle made by the groove surface of the header pipe and the surface of the tube is from 15 to 45 degrees. Preferably, an outer groove angle θ1 at the outside of the header pipe is rendered larger than an inner groove angle θ2 at the inside, and the tube surface should be provided with a wax material layer to attain a good brazing condition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat exchanger having a pair of header pipes and a plurality of tubes installed between the header pipes, and more particularly, to brazing of header pipes and tubes. It is related to technology for improving sex.

[0002]

2. Description of the Related Art Conventionally, in a heat exchanger used for an air conditioner or an automobile, a space between a pair of right and left pipes called a header pipe is maintained at right angles to the header pipe and parallel to each other. A large number of tubes are erected, the ends of each tube are connected to the side of the header pipe, the internal space of each tube communicates with the internal space of the header pipe, and a fin member is arranged between the multiple tubes. A heat exchanger having a structure with improved heat exchange properties is known. In this type of heat exchanger, the heat medium circulates through the inside of the header pipe and the inside of each tube, and the heat medium can exchange heat via fins arranged between the tubes. Usually, this type of heat exchanger is made of aluminum or aluminum alloy having good heat conductivity, and the header pipe and the tube or the tube and the fin are joined by brazing material. Therefore, a header pipe made of a brazing sheet in which a brazing material layer of an aluminum-silicon alloy or the like is clad and pressure-bonded to an aluminum alloy plate in advance is used in consideration of brazing properties. And a slit for tube insertion is formed in this header pipe, the tube is inserted into this slit, the brazing material layer is heated and melted and fluidized, the surroundings of the insertion part are covered with brazing material, and then cooled, Brazing the tube to the pipe.

[0003] When assembling the heat exchanger having the above-described structure, the inner diameter of the slit is generally formed larger than the outer diameter of the tube in order to easily insert the tube into the slit of the header pipe. In this case, a large gap is formed between the slit of the header pipe and the tube, so that the required amount of brazing material also increases, and since the brazing material is not easily gathered at the joint,
Brazing failure was apt to occur, and there was a problem in the confidentiality of the heat exchanger. In order to solve this problem, as shown in FIG. 6, the applicant of the present invention made the outer openings of the tube insertion slits 6 of the header pipes 1 and 2 into an outwardly extending mortar-shaped groove. Formed, in the cross section of the tube insertion portion of the header pipes 1, 2, the header pipe 1,
The angle between the groove surface of the tube 2 and the surface of the tube 3 is proposed to be 10 to 80 degrees (Japanese Patent Laid-Open No. 9-26).
9200). According to this method, it is expected that the brazing material is caused to flow to the joining portion by the capillary force acting on the minute gap at the groove portion, and the joining is reliably performed with a small amount of brazing material.

[0004]

However, since the header pipe is thicker than the tube or the fin,
As compared to the outside of the header pipe, the temperature inside the header pipe is less likely to rise, so that the flowability of the melted brazing material is reduced inside the header pipe. Therefore, the brazing material flows only outside the high-temperature header pipe. Therefore, even when a mortar-shaped groove is provided on the outside of the header pipe, the brazing material easily flows at the joint on the outside of the header pipe and forms a preferable fillet, but the flow deteriorates inside the header pipe. Therefore, a sufficient fillet is not formed, and the cause of the insufficient filling of the brazing filler metal has not yet been solved.

[0005]

According to a first aspect of the present invention, there is provided a pair of header pipes, a plurality of tubes provided between the header pipes, and fins attached to the tubes. In the heat exchanger formed as described above, a header in which a groove formed in a mortar shape that spreads outward was provided at both the outer opening and the inner opening of the slit for inserting the tube of the header pipe. By providing a mortar-shaped groove on both the outer opening and the inner opening of the slit for inserting the tube of the header pipe, the capillary force easily works at the groove, and the inside of the header pipe where the temperature tends to be low However, the brazing material can easily flow, and the cause of the insufficient filling of the brazing material can be eliminated. Also,
In the present invention, the groove angle formed in a mortar shape is 15
It is appropriate to set it to 45 degrees. If the groove angle is too small, it becomes difficult for the melted brazing material to enter the groove by capillary force, and if it is too large, the amount of brazing material required for joining increases. Preferably, the groove angle is 25 to 35 degrees. In the present invention, the groove angle of the outer opening is preferably equal to or larger than the groove angle of the inner opening. This is because the temperature of the outer opening is likely to be high, and the fluidity of the brazing filler metal is good. On the other hand, the temperature of the inner opening tends to be low and the fluidity of the brazing material is poor, so that the groove angle is reduced so that the capillary force easily acts on the brazing material. In the present invention, the cross-sectional shape of the tube may be circular or a multi-hole flat tube having a substantially rectangular cross-sectional shape. The material of the header pipe and the tube is preferably made of an aluminum alloy from the viewpoint of heat exchange and workability. Further, in the present invention, it is preferable that a brazing material layer is formed in advance on the tube surface where the joint portion with the header pipe is provided. The heat exchanger of the present invention uses the above-described header having excellent brazing properties for the header portion. The heat exchanger of the present invention is a heat exchanger which is easy to manufacture with a low occurrence of a defective rate due to defective bonding in a manufacturing process and has an excellent heat exchange rate.

[0006]

FIG. 1 shows an example of a heat exchanger according to the present invention. This heat exchanger 100 includes header pipes 1 and 2 arranged on the left and right, and header pipes 1 and 2 on the left and right. A plurality of tubes 3 joined in parallel at a distance from each other and perpendicular to the header pipes 1 and 2, and corrugated fins 4 arranged in the tubes 3 are mainly constituted. The header pipes 1 and 2, the tube 3 and the fins 4 are each made of an aluminum alloy having good heat conductivity.

FIG. 2 shows a sectional structure of a header pipe and a tube before fusion bonding. For the header pipes 1 and (2) with a circular cross section,
A brazing material layer 5 made of a brazing alloy is provided on the surface of (2). When the tube 3 is inserted into the slits 6 provided on the inner surfaces of the header pipes 1 and 2 facing each other and the brazing material layer 5 is melted, the molten brazing material flows into the gap between the header pipe and the tube. Then, the tube 3 and the header pipes 1 and (2) are joined by solidifying and filling the header pipe connection portion of the tube 3. The contact portions between the tubes and the fins are also joined by the brazing material.

Here, an Al-Si brazing material is mainly used as a brazing material for joining the header pipes 1, (2) and the tube 3 and a brazing material for joining the tube 3 and the fins 4. Examples of the Al-Si brazing material include a 4343 alloy containing 6.8 to 8.2 wt% of Si,
i: 4045 alloy containing 9.0-11.0 wt% is used. In addition, Al-Si-Zn-based brazing materials and Al-
It may be a Si-Cu-based brazing material.

Normally, a brazing material obtained by clad rolling the above brazing material with an aluminum alloy having a high thermal conductivity is used as a header pipe material or a fin material.
Further, the above brazing material may be powdered, mixed with a flux or a binder, applied to the surface of a header pipe material or a tube material, and provided with a brazing material layer.

In the present invention, it is more preferable to use a brazing material layer provided on the surface of the header pipe and the tube. In this case, the fin has a high thermal conductivity of 3003.
Use alloy. By installing the brazing material layer on the surface of the tube in advance, the molten brazing material easily flows toward the groove provided in both the outer opening and the inner opening of the slit of the header pipe described below, A fillet is formed more reliably by the joint, and it is possible to prevent a joint failure.

In the present invention, both the outer opening and the inner opening of the slit for inserting the tube of the header pipe are provided.
An outer groove and an inner groove formed in a mortar shape spreading outside are provided. An example is shown in FIG. FIG. 3 is a vertical cross-sectional view taken along line XX ′ of FIG. 2 for explaining a joint state between the header pipe and the tube. In FIG. 3, the tube 3 is inserted from the lateral direction into the slit 6 for inserting the tube of the header pipes 1 and (2) extending vertically. The slits 6 of the header pipes 1 and (2) are formed with an outer groove 11 and an inner groove 12 which are formed in a mortar shape which spreads outward on both sides in the thickness direction of the pipe. The groove angles θ1 and θ2 formed by the outer groove 11 and the inner groove 12 of the header pipes 1 and (2) and the tube 3 are all 15 to
An angle of 45 degrees is appropriate. If the included angle is less than 15 degrees, the interval between the header pipes 1, (2) and the tube 3 becomes narrow, and moreover, the header pipes 1, (2) and the tube 3
The distance to the adjacent point is too large, so that the brazing material melted by the capillary force cannot sufficiently penetrate, and this is likely to cause bonding failure. When the included angle is 45 degrees or more, the capillary force stops working, the fillet 7 formed by solidification of the molten brazing material is small, and a large amount of brazing is required to securely join the header pipes 1, (2) and the tube 3. This is because wood is required. More preferably, the groove angle is suitably 25 to 35 degrees.

The groove angle θ between the outer groove 11 and the inner groove 12
1 and θ2 may be equal in the range of 15 to 45 degrees, but it is preferable that the inner groove angle θ2 be smaller than the outer groove angle θ1. FIG. 4 shows an example of this groove. In FIG. 4, the inner groove angle θ2 formed by the inner groove 12 is:
It is smaller than the outer groove angle θ1 formed by the outer groove 11. Since the header pipe has a relatively large thickness, the temperature of the outside (surface portion) of the header pipe is higher than that of the inside (middle portion) of the header pipe during brazing, and the flowability of the brazing material is good. On the other hand, since the temperature inside the header pipe (the middle part) hardly rises, the fluidity of the brazing filler metal is not good. Therefore, it is effective to make the groove angle θ2 of the inner groove 12 small to easily generate capillary force and to promote the flow of the brazing material.

As described above, by providing both the outer groove and the inner groove on both sides of the thickness of the header pipe, the molten brazing material in the vicinity of the joining portion is removed by utilizing the capillary force acting on the groove. The fluid can be reliably flowed to the outer and inner joints of the pipe, and the gap between the header pipe and the tube can be completely filled. As a result, leakage of the refrigerant due to poor brazing is eliminated, and a heat exchanger excellent in heat exchange property is obtained.

In the present invention, the cross-sectional shape of the header pipe is not limited to a pipe having a circular cross section as shown in FIG. 2, but may be a square pipe having a rectangular cross section. Further, the cross-sectional shape of the tube is not limited to a pipe having a circular cross-section, and a flat tube with a multi-hole having a substantially rectangular cross-section as shown in FIG.

[0015]

According to the present invention, there is provided a heat exchanger comprising a pair of header pipes, a plurality of tubes provided between the header pipes, and fins attached to the tubes. Is a heat exchanger using a header provided with a groove formed in a mortar shape that spreads outward on both the outer opening and the inner opening. By providing a mortar-shaped groove on both the outer opening and the inner opening of the slit for inserting the tube of the header pipe, even inside the header pipe where the temperature tends to be low, the brazing material can be utilized by using the capillary force. The filler is easily filled, and the cause of the poor filling of the brazing filler metal is eliminated.

[0016]

Embodiments will be described below with reference to embodiments. (Example 1) An aluminum alloy has a circular section pipe, a tube, and a fin.
The heat exchanger as shown in was manufactured. As the header pipe material, an electric resistance welded tube made of a clad material of 3003 alloy on the inside and 4045 alloy on the outside was used. In this embodiment, a header pipe pre-clad with a brazing material was used. The composition of the 4045 alloy used as the brazing filler metal used for joining is Al-10.0 wt% Si. An extruded flat tube made of 1050 alloy was used as the tube material. The fin material includes 4045 alloy / 3003 alloy / 404
A three-layer clad material of five alloys was used. A side provided with a plurality of slits for inserting a tube was used on the side surface of the header pipe. On the outside (front side) and inside (inside side) of the slit portion of the header pipe, a mortar-shaped groove extending outward was provided. When the tube was inserted into the header pipe at the groove portion, the groove angles θ1 and θ2 formed between the groove surface of the header pipe and the tube surface were set to the values shown in Table 1. The included angle was the same outside (front side) and inside (inside side) of the slit portion. In order to provide a groove on both the front and back surfaces of the header pipe, an electric resistance welded tube was created using a material that had been diced at a predetermined angle at a predetermined position of the clad material to be processed into the header pipe in advance. .

After assembling the header pipe, tube and fin, brazing was performed at 600 ° C. for 3 minutes to produce a heat exchanger. Table 1 also shows the result of observation of the joining state between the header pipe and the tube of the obtained heat exchanger. In Table 1, when the molten brazing material forms a fillet and completely fills the gap between the slit and the tube of the header pipe, the mark “印” indicates that the fillet has not been completely formed and the slit and the tube of the header pipe have not been completed. When the gap was not filled, the cross mark was given.

[0018]

[Table 1]

From the results shown in Table 1, the groove angles θ1 and θ2 are 1
In the case of 5 ° to 45 °, a fillet is formed well, the gap between the slit of the header pipe and the tube is completely filled, and a heat exchanger having good heat exchange without heat medium leakage is obtained. It turns out that it is possible. If the groove angles θ1 and θ2 are less than 15 ° or more than 45 °, a bonding failure occurs.

(Embodiment 2) The groove angles θ1 and θ2 between the groove surface of the header pipe and the tube surface are increased as shown in Table 2 by increasing the outside (front surface side) of the slit portion to the inside (inside surface side). A heat exchanger was manufactured in the same manner as in Example 1 except that the size of the heat exchanger was reduced. Table 2 also shows the result of observation of the joining state between the header pipe and the tube of the obtained heat exchanger. In Table 2, when the melted brazing material forms a fillet and completely fills the gap between the slit of the header pipe and the tube, it is indicated by ○, and when the size of the fillet is larger than that of Example 1, ◎ is marked.

[0021]

[Table 2]

From the results shown in Table 2, the groove angle is 15 ° to 35 °.
It can be seen that good fillets are formed at all the groove portions where the angle is °. Also, from the results of Tables 1 and 2, it can be seen that when the groove angle θ2 inside the header pipe is smaller than the groove angle θ1 outside, the formation of the fillet inside the header pipe becomes better.

(Embodiment 3) Next, as in the first embodiment, the inside of the header pipe was made of 3003 alloy and the outside was made of 40%.
An electric resistance welded tube made of a clad material of 45 alloy was used, and a tube material provided with a brazing material layer made of 4045 alloy on the surface of an extruded flat tube made of 1050 alloy was used. Also, a fin material made of 3003 alloy was used. Using such a material, a heat exchanger was manufactured in the same manner as in Example 1 by making a groove in the slit for inserting the tube of the header pipe. The groove angle was the same for θ1 and θ2. The brazing conditions were set to 600 in the same manner as in the first embodiment.
C. x 3 minutes. Table 3 shows the results of observation of the joining state between the header pipe and the tube of the obtained heat exchanger. In Table 3, when the molten brazing material formed a fillet and completely filled the gap between the slit of the header pipe and the tube and the fillet size became larger than in Example 1, a mark ◎ was given.

[0024]

[Table 3]

Comparing the results in Tables 1 and 3, when the brazing filler metal layer is not formed on the surface of the tube, the fillet formation state is better and a good bonding state is achieved. It is understood that it is done.

[0026]

By providing a mortar-shaped groove in both the outer opening and the inner opening of the slit for inserting the tube of the header pipe, the capillary phenomenon acts even inside the header pipe where the temperature tends to be low. As a result, the brazing material can be made to flow easily, and the cause of defective filling of the brazing material can be eliminated. As a result, leakage of the refrigerant due to poor brazing is eliminated, and a heat exchanger excellent in heat exchange property is obtained.

[Brief description of the drawings]

FIG. 1 is an external view illustrating the structure of a heat exchanger.

FIG. 2 is a cross-sectional view taken along line XX ′ of FIG. 1 for explaining a joint state between the header pipe and the tube.

FIG. 3 is a sectional view taken along the line X-X 'of FIG.

FIG. 4 is a sectional view of another example taken along line XX ′ of FIG. 2;

FIG. 5 is an external view showing an example of a tube.

FIG. 6 is a view for explaining a conventional joint state between a header pipe and a tube.

[Explanation of symbols]

1, 2, ... header pipe, 3 ... tube, 4 ...
・ Fin, 5 ・ ・ ・ ・ ・ ・ ・ brazing material layer, 6 ・ ・ ・ ・ ・ ・ ・ slit, 7 ・ ・ ・ ・ ・ ・ ・
Brazing filler metal layer (fillet), 11 ... Outside groove, 1
2 ····· Inner groove, 31 ···· Hole, 100 ····· Heat exchanger

Claims (6)

[Claims] 1. A heat exchanger comprising a pair of header pipes, a plurality of tubes provided between the header pipes, and fins attached to the tubes.
A heat exchanger excellent in brazing characteristics, characterized in that both the outer opening and the inner opening of the slit for inserting the tube of the header pipe have a groove formed in a mortar shape that spreads outward. . 2. The heat exchange excellent in brazing properties according to claim 1, wherein the angle of the mortar-shaped groove formed on the header pipe is 15 to 45 degrees. vessel. 3. The heat exchange excellent in brazing property according to claim 1, wherein a groove angle of the outer opening is equal to or larger than a groove angle of the inner opening. vessel. 4. The heat exchanger excellent in brazing properties according to claim 1, wherein the tube is a multi-hole flat tube having a substantially rectangular cross section. 5. The header pipe and the tube are made of an aluminum alloy.
A heat exchanger excellent in brazing properties according to any one of the above. 6. The heat-excelling brazing property according to claim 1, wherein a brazing material layer is provided on the tube surface on which the joint portion with the header pipe is provided. Exchanger.