JP6333468B2 - Tube connection structure and heat exchanger - Google Patents

Description

  The present invention relates to a pipe connection structure and a heat exchanger capable of accurately connecting two pipe bodies by brazing.

  2. Description of the Related Art A heat exchanger used for an automobile, household, or commercial air conditioner includes fins, a tube through which a refrigerant passes, and a header that delivers the refrigerant to the tube. The header is mainly formed of a metal material. And on the side surface of the header, a portion (hereinafter referred to as a header side joint) where a tube and a branch pipe joined to the tube (hereinafter referred to as a pipe joint) are inserted and joined is formed by burring or the like. Yes. A heat exchanger is configured by joining the tube and the pipe joint at the header side joint.

  As this joining method, brazing is often selected. At this time, when the header side joint is formed outside by burring, there is a problem that the clearance is not constant depending on the shape of the processed hole, and brazing is not stable. Further, when brazing is performed, there is a problem that flux and brazing material spill out, resulting in deterioration of brazing performance and unnecessary joining of peripheral members.

  In order to solve these problems, in the conventional heat exchanger, the header joint portion is formed on the inner side, and the tip end portion of the header joint portion is formed smaller than the wedge shape or the outer diameter of the insertion tube. And brazing property is improved by forming the wax pool and stabilizing the clearance.

  For example, Patent Document 1 discloses that a header-side joint portion is molded under a condition in which a wedge shape is formed at a tip portion by burring in a header tank of a stacked heat exchanger and a joint portion of a flat tube. The flux that melts at the time of brazing, the guide part of the brazing material, and the brazing pool part are formed to improve the brazing property.

  Further, for example, in Patent Document 2, a header side joint is formed inside the header side by burring, and is processed to be smaller than the outer diameter of the tube into which the burring tip is inserted. Adheres closely, suppresses variations in clearance, and improves brazing.

JP 07-305992 A JP 2009-14270 A

  The conventional tube connection structure is used in automotive heat exchangers that connect all the tubes directly to the header, but heat pump air conditioners for home and commercial use further increase the efficiency of the heat exchanger. There is a need. Therefore, in order to reduce the pressure loss in the header side joint, it is necessary to form the header side joint on the outside. For this reason, in the connection structure of the conventional pipe body, there existed a problem that the countermeasure which improves the brazing property by the front-end | tip shape which forms the header side junction part inside was difficult.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a tube connection structure and a heat exchanger that can be brazed with high accuracy.

The connecting structure of the tubular body of this invention is
In the connection structure of the tube connecting the first tube and the second tube,
The first tubular body has a protruding wall in which a part of the side wall protrudes outward to form an opening,
The second tube has an insertion tube portion whose end is inserted into the opening of the protruding wall, and an outer tube portion that communicates with the insertion tube portion and is external to the protruding wall.
The outer tube portion has a tube connection structure formed so that the tube diameter is smaller than the tube diameter of the insertion tube portion, and the protrusion on the side wall on the outer peripheral side of the protrusion wall of the first tube body A recess is formed over the entire circumference of the wall .

Moreover, the heat exchanger of this invention is
A tube through which the refrigerant passes;
Laminating a plurality of fins, a core portion through which the tube penetrates each fin,
A header formed outside the core portion;
In the heat exchanger having the tube and the connecting pipe connected to the header,
The pipe connecting structure of the header and the connecting pipe is formed by using the first pipe of the pipe connecting structure described above as the header and the second pipe as the connecting pipe.
Moreover, the heat exchanger of this invention is
A tube through which the refrigerant passes;
Laminating a plurality of fins, a core portion through which the tube penetrates each fin,
A header formed outside the core portion;
In the heat exchanger having the tube and the connecting pipe connected to the header,
The connection structure of the pipe body between the header and the connection pipe is as follows:
In the connection structure of the tubular body that connects the first tubular body and the second tubular body,
The first tubular body has a protruding wall in which a part of the side wall protrudes outward to form an opening,
The second tube has an insertion tube portion whose end is inserted into the opening of the protruding wall, and an outer tube portion that communicates with the insertion tube portion and is external to the protruding wall.
The tube diameter of the outer tube portion is smaller than the tube diameter of the insertion tube portion, and is a connection structure of the tube body, wherein the first tube body of the tube connection structure is the header, A two-pipe body is formed as the connecting pipe.

  According to the tubular body connection structure and the heat exchanger of the present invention, it is possible to accurately connect the two tubular bodies by brazing.

It is sectional drawing which shows the structure of the connection structure of the tubular body in Embodiment 1 of this invention. It is an expanded sectional view which shows the detail of the connection structure of the tubular body shown in FIG. It is sectional drawing which shows the brazing state of the connection structure of the tubular body shown in FIG. It is sectional drawing which shows the brazing state of the connection structure of the tubular body shown in FIG. It is sectional drawing which shows the other structure of the connection structure of the tubular body in Embodiment 1 of this invention. It is sectional drawing which shows the other structure of the connection structure of the tubular body in Embodiment 1 of this invention. It is sectional drawing which shows the other structure of the connection structure of the tubular body in Embodiment 1 of this invention. It is sectional drawing which shows the other structure of the connection structure of the tubular body in Embodiment 1 of this invention. It is a perspective view which shows the structure of the heat exchanger using the connection structure of the tubular body shown in FIG. It is a circuit diagram which shows the refrigerant circuit using the heat exchanger shown in FIG. It is sectional drawing which shows the structure of the connection structure of the tubular body in Embodiment 2 of this invention. It is sectional drawing which shows the other structure of the connection structure of the tubular body in Embodiment 2 of this invention. It is sectional drawing which shows the other structure of the connection structure of the tubular body in Embodiment 2 of this invention.

Embodiment 1 FIG.
Embodiments of the present invention will be described below.
1 is a cross-sectional view showing a configuration of a tubular body connection structure according to Embodiment 1 of the present invention.
FIG. 2 is an enlarged cross-sectional view showing details of the tube connection structure shown in FIG.
FIG. 3 is a cross-sectional view showing a brazed state of the tube connecting structure shown in FIG.
4 is a cross-sectional view showing a brazed state of the tube connecting structure shown in FIG.
6 to 8 are cross-sectional views showing other configurations of the tube connecting structure according to Embodiment 1 of the present invention.
FIG. 9 is a perspective view showing a configuration of a heat exchanger using the tube connection structure shown in FIG.
FIG. 10 is a circuit diagram showing a refrigerant circuit using the heat exchanger shown in FIG.

  In the figure, the connection structure of the tubular body is for connecting the first tubular body 1 and the second tubular body 2. The first tubular body 1 is formed with a protruding wall 12 at a predetermined location on the side wall 11, with a part of the side wall 11 protruding outward. The thickness of the side wall 11 is the thickness D. The protruding wall 12 is formed by cutting the side wall 11 of the first tubular body 1 by burring or bulging. The projecting wall 12 forms an opening 13 inside thereof. The length of the protruding wall 12 is the length F. The opening 13 is a portion that communicates from the inside to the outside of the first tubular body 1.

  The second tubular body 2 has an insertion tube portion 21 whose end portion is inserted into the opening portion 13 of the protruding wall 12, and an outer tube portion 22 that communicates with the insertion tube portion 21 and is external to the protruding wall 12. have. The tube diameter C of the outer tube portion 22 is smaller than the tube diameter B of the insertion tube portion 21 (B> C) (the tube diameter B of the insertion tube portion 21 is larger than the tube diameter C of the outer tube portion 22). It can also be said that it is a diameter.)

  The outer shape of the outer tube portion 22 on the insertion tube portion 21 side is formed by an inclined surface 22A. Since the tube diameter C of the outer tube portion 22 is smaller than the tube diameter B of the insertion tube portion 21, the inclination angle θ of the inclined surface 22A is formed such that 0 ° <θ <90 °. Further, the tube diameter B of the insertion tube portion 21 and the opening diameter A of the opening portion 13 are formed substantially the same so that the insertion tube portion 21 can be inserted into the opening portion 13 (A≈B).

  The length of the insertion tube portion 21 is a length E. The insertion tube portion 21 is inserted inside the outer end 12 </ b> A of the protruding wall 12. The length E of the insertion tube portion 21 is shorter than the length F of the protruding wall 12, and the uppermost end of the insertion tube portion 21 is at a position lower than the outer end 12 </ b> A of the protruding wall 12. Accordingly, a space 30 is formed between the protruding wall 12 and the outer tube portion 22 on the outer end 12 </ b> A side of the protruding wall 12.

  In the first embodiment, the position of the lowermost end 2AA of the second tubular body 2 and the inner wall end 1A of the inner wall of the first tubular body 1 are on the same plane position, which is an ideal positional relationship. An example of arrangement is shown. However, the present invention is not limited to this, and the positions of the lowermost end 2AA of the second tubular body 2 and the inner wall end 1A of the inner wall of the first tubular body 1 may be slightly shifted from the same plane position. . This also applies to the following embodiments, and the description thereof will be omitted as appropriate.

  And the connection structure of a pipe body is comprised so that the 1st pipe body 1 and the 2nd pipe body 2 may be shown in FIG. 1 and FIG. With this configuration, when brazing is performed, if the flux and brazing material at brazing are installed on the inclined surface 22A, the melted flux and brazing material are guided by the inclined surface 22A, and then the inclined surface 22A. Flowing along. Therefore, the flux and the brazing material can easily flow between the insertion tube portion 21 of the second tubular body 2 and the protruding wall 12 of the first tubular body 1, which is a portion to be brazed.

  When brazing is performed, the brazed portion 4 is formed as shown in FIGS. As shown in the figure, the flux and brazing material flow into the space 30 between the outer tube portion 22 of the second tube 2 and the protruding wall 12 of the first tube 1, and the brazed portion 4 is formed. Therefore, the flux and brazing material are prevented from spilling from the protruding wall 12 of the first tubular body 1 to the outside.

  Also, the flux and brazing material receive heat from both the first tubular body 1 and the second tubular body 2 during brazing and are easily melted, and contact portions between components due to the presence of the flux and brazing material As a result, the temperature difference between the components being heated is reduced, and it becomes possible to form a tube connection structure with stable brazing.

  Further, here, since the tube diameter B of the insertion tube portion 21 of the second tubular body 2 and the opening diameter A of the opening portion 13 of the first tubular body 1 are formed to have the same diameter, The initial contact between the insertion tube portion 21 of the two-tube body 2 and the projecting wall 12 of the first tube body 1 reduces the temperature difference between them, and the gap formed between them becomes small, so that the brazing material penetration due to capillary action Therefore, it is possible to form a tube connection structure with good brazing.

  Moreover, since what is inserted into the opening 13 of the first tubular body 1 is the insertion tubular portion 21 at one end of the second tubular body 2, the brazed portions 4 of the second tubular body 2 are individually heated. It can be controlled and the brazing quality is easy to control. Moreover, since the insertion tube part 21 should just be formed only in the edge part of the one side of the 2nd pipe body 2, a process becomes simple. Note that the insertion tube portion 21 of the present embodiment may be formed at both ends of the second tube 2 depending on the connection configuration of the tube.

  In the above, the example in which the inclined surface 22A is formed by a surface having a corner has been described, but the present invention is not limited to this. For example, as shown in FIG. 5, an example in which the inclined surface 22B is formed of an R chamfered surface having a curvature radius R1 (R1> 0) is also conceivable. If formed in this way, the flow of the melted flux and brazing material along the inclined surface 22B becomes gentle, and the prevention of spillage can be further enhanced.

  Moreover, in the above, although the example which forms inclined surface 22A, 22B was shown, it is not restricted to this. For example, as shown in FIG. 6, an example in which the insertion tube portion 21 and the outer tube portion 22 are formed to communicate with each other through a step surface 22C is also conceivable. If formed in this way, the melted flux and brazing material can be held at one end on the stepped surface 22C, thereby preventing spillage.

  In the above description, the insertion tube portion 21 is inserted inside the outer end 12A of the protruding wall 12, but the present invention is not limited thereto. For example, as shown in FIG. 7, a part of the insertion tube portion 21 is inserted inside the outer end 12A of the protruding wall 12, and a part of the insertion tube portion 21 is the same as or slightly outside the outer end 12A of the protruding wall 12. An example of insertion is also conceivable. If formed in this way, although the space 30 is not formed, the melted flux and brazing material flow to the outer end 12A of the protruding wall 12 along the inclined surface 22A, so that it is possible to prevent outflow to other places. it can.

  Moreover, in the above, although the example which forms the pipe diameter B of the insertion pipe part 21 and the opening diameter A of the opening part 13 of the protrusion wall 12 with the same magnitude | size was shown, it is not restricted to this. . For example, as shown in FIG. 8, the tube diameter B1 of the insertion tube portion 21 is formed smaller than the opening diameter A of the opening portion 13 of the protruding wall 12 so that the insertion tube portion 21 can be easily inserted into the opening portion 13 of the protruding wall 12. An example of forming is also conceivable. If formed in this way, a gap 40 is formed between the insertion tube portion 21 and the opening 13 of the protruding wall 12, but the flux and brazing material melted in the gap 40 are applied to the inclined surface 22A. It can be easily inserted along and can be prevented from flowing out to other places.

  In addition, in the above, although the example which forms both the 1st pipe body 1 and the 2nd pipe body 2 in the tubular shape was shown, it is not restricted to this, Tubular shape other than circular pipes, such as flat shape Can be formed.

  And as a location where such a pipe connection structure is used, there is a heat exchanger 100 as shown in FIG. And such a heat exchanger 100 is provided in the refrigerant circuit of the air conditioning apparatus which mainly uses a gas-liquid two-phase fluid as a refrigerant | coolant as shown in FIG. As shown in FIG. 10, the heat exchanger 100 is connected to an expansion valve mechanism 300 such as a compressor 200 or a capillary tube, and is used as an evaporator or a condenser.

  As shown in FIG. 9, the heat exchanger 100 includes a tube 101, a core portion 102, a header 10, and a connecting pipe 20. The tube 101 is a tube through which the refrigerant passes. The core part 102 is formed by laminating a plurality of fins 105. And the tube 101 has penetrated these fins 105. A plurality of the tubes 101 are formed. The header 10 is formed outside the core unit 102. The connecting pipe 20 connects the tube 101 and the header 10. The header 10 is introduced with refrigerant from the tube 101 inside. The refrigerant circulates between the different tubes 101 via the header 10 outside the fins 105.

  In the first embodiment, in the heat exchanger 100, the connection pipe 20 and the tube 101 are formed of different components. However, the present invention is not limited to this, and one end of the tube 101 is formed. Can also function as the connecting pipe 20, and the same effect can be obtained. The same applies to the following embodiments, and the contents thereof are omitted as appropriate. However, if the connecting pipe 20 and the tube 101 are formed of different components, the degree of freedom of the shape of the connecting pipe 20 is improved.

  And the connection structure of the pipe body of the header 10 and the connection pipe 20 thus configured is formed with the first pipe body 1 shown above as the header 10 and the second pipe body 2 as the connection pipe 20. Is. Further, although an example in which one header 10 is provided is shown here, the present invention is not limited to this, and a plurality of headers 10 can be formed.

  Next, the materials of the first tubular body 1 and the second tubular body 2 will be described. The first tubular body 1 and the second tubular body 2 are formed of the same kind of metal material. For example, an aluminum alloy, copper, or copper alloy having high thermal conductivity is used. And these joining is performed by brazing in an atmospheric furnace or brazing by heating with a burner or a heater in the air. In particular, when an aluminum alloy is used, an aluminum-silicon brazing material is used and a non-corrosive flux is used.

  Thus, by comprising the 1st pipe body 1 and the 2nd pipe body 2 with the same kind metal material, when performing brazing of a dissimilar metal, the intermetallic compound layer produced in a brazing part can be suppressed. it can. Furthermore, it is not necessary to consider the influence of electrical corrosion between different metals. In addition, by using any one of aluminum alloy, copper, and copper alloy having high thermal conductivity, heat exchange can be performed even when the refrigerant passing through the inside passes through the header 10, and the heat of the entire heat exchanger Exchange performance can be improved. Furthermore, since these metals can be brazed in an atmosphere furnace or in the air, options for the bonding method are widened, and it is easy to find stable brazing conditions. In addition, although the example which comprises the 1st pipe body 1 and the 2nd pipe body 2 with the same kind of metal material was shown, it is not restricted to this, The 1st pipe body 1 and the 2nd pipe body 2 are different. It can also be made of a metal material, and as shown above, it cannot produce the effect of being made of the same kind of metal material, but if it can be brazed, it can be made of a material that is low in cost. Can be selected.

  According to the tube connection structure and the heat exchanger of the first embodiment configured as described above, the tube diameter of the outer tube portion of the second tube body is formed smaller than the tube diameter of the insertion tube portion, and the step portion is formed. Therefore, it is possible to prevent the melted flux and brazing material from staying at that portion and flowing out to the outside. Therefore, it is possible to find a stable brazing condition. And since the projecting wall of the first tubular body is formed so as to project outward rather than inward, the pressure of the refrigerant that flows into the first tubular body, for example, compared to the case where it is formed inside the first tubular body. Loss can be reduced.

  Moreover, since the outer shape of the insertion tube portion side of the outer tube portion is formed by an inclined surface, if flux and brazing material are installed on this inclined surface during brazing, the outer tube portion flows along the inclined surface, and the tube body It is difficult for flux and brazing material to flow out to other parts other than the connection location, and stable brazing conditions can be found.

  In addition, when the inclined surface is formed by an R chamfered surface, the melted flux and brazing material gently flow through the inclined surface and hardly flow out to other portions.

  Further, since the insertion tube portion is inserted inside the outer end of the protruding wall, a space portion is formed between the outer tube portion and the protruding wall, and the molten flux and brazing material flow into the space portion, Outflow to other parts is less likely to occur.

  In addition, by forming the first tube and the second tube from the same metal material, the intermetallic compound layer generated when brazing between dissimilar metals is suppressed and the possibility of electrical corrosion between dissimilar metals is reduced. Can be suppressed. In addition, by forming it with a metal material having high thermal conductivity, not only when the refrigerant passes through the second tube, but also when it passes through the first tube, heat exchange with the outside air (heat exchange) For example, the overall heat exchange performance of the heat exchanger can be improved.

Embodiment 2. FIG.
FIG. 11 is a cross-sectional view showing a configuration of a tube connection structure according to Embodiment 2 of the present invention. 12 and 13 are cross-sectional views showing another configuration of the tube connection structure according to Embodiment 2 of the present invention. In the figure, the same parts as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted. In the second embodiment, a recess is formed in the side wall 11 on the outer peripheral side of the protruding wall 12 of the first tubular body 1 over the entire periphery of the protruding wall 12.

  For example, as shown in FIG. 11, the concave portion 31 has a trapezoidal concave portion 31, a triangular concave portion 32 as shown in FIG. 12, and a bottom portion as shown in FIG. May be formed by the concave portions 33 each having a curved surface 33A having a radius of curvature R. In this case, the depths H, M, and P + R of the recesses 31, 32, and 33 are formed to be less than 50% of the thickness D of the side wall 11 of the first tubular body 1. This is to ensure the strength of the location of the side wall 11 of the first tubular body 1 where the respective recesses 31, 32, 33 are formed. The depth of the recess 33 is obtained by adding the depth P of the inclined portion of the recess 33 and the radius of curvature R of the curved surface 33A.

  Further, the volumes V1, V2, and V3 of the recesses 31, 32, and 33 can be obtained by the following (Expression 1), (Expression 2), and (Expression 3), respectively. In addition, the value (length) of each recessed part 31, 32, 33, the value (length) required in order to obtain | require a volume, etc. are set as shown in each figure. That is, B is the tube diameter of the insertion tube portion 21, C is the tube diameter of the outer tube portion 22, D is the thickness of the side wall 11, E is the length of the insertion tube portion 21, F is the length of the protruding wall 12, and H Is the depth of the recess 31, J is the maximum width of the recess 31, K is the minimum width of the recess 31, M is the depth of the recess 32, N is the maximum width of the recess 32, P is the depth of the inclined portion of the recess 33, Q represents the maximum width of the recess 33, and R represents the radius of curvature of the curved surface 33A.

V1 = 0.5Hπ × (K + J) × (B + 2S + J) (Formula 1)
V2 = 0.5NMπ × (B + 2S + N) (Formula 2)
V3 = 0.5π × (πR∧2 + QP + 2RP) × (B + Q + 2S)
... (Formula 3)

Here, assuming that the volume V of the brazing material used for brazing and the volume V0 of the portion to be filled with the brazing material, the following formulas (4) are established for the volumes V1, V2, and V3 of the recesses 31, 32, and 33. Is a condition.
V1 or V2 or V3 ≧ V−V0 (Formula 4)

  The lengths of the respective portions of the recesses 31, 32, and 33 are determined based on the above (Expression 1), (Expression 2), and (Expression 3) so that (Expression 4) is satisfied.

  In addition, it is also possible to use the other structure shown in the said Embodiment 1 for structures other than a recessed part, Furthermore, the heat | fever using the brazing method, the material of each tube, and the connection structure of a tube Since the exchanger and the like are the same as those in the first embodiment, description thereof will be omitted as appropriate.

  The tube connection structure and heat exchanger of the second embodiment configured as described above have the same effects as those of the first embodiment, and the flux and brazing material overflow to the outside. Can also flow into the recess, and further prevent unnecessary flow out to the outside.

  Furthermore, by forming the bottom of the recess with a curved surface, it is possible to reduce stress concentration at the bottom of the recess.

  It should be noted that the present invention can be freely combined with each other within the scope of the invention, and each embodiment can be appropriately modified or omitted.

Claims (17)

In the connection structure of the tube connecting the first tube and the second tube,
The first tubular body has a protruding wall in which a part of the side wall protrudes outward to form an opening,
The second tube has an insertion tube portion whose end is inserted into the opening of the protruding wall, and an outer tube portion that communicates with the insertion tube portion and is external to the protruding wall.
Said tube diameter of the outer tube portion a connecting structure of the tube body is formed smaller than the tube diameter of the insertion tube portion, the side wall of the outer peripheral side of the protruding wall of the first tubular body, the protrusion connection structure that the tube is formed a recess over the entire circumference of the wall. The depth of the recess of the first tubular body, the connection structure of the tube body according to claim 1, which is formed at less than 50% of the thickness of the side wall of the first tube. The tubular body connection structure according to claim 2 , wherein the concave portion of the first tubular body has a curved bottom surface. 4. The tubular body connection structure according to claim 1 , wherein an outer shape of the outer tube portion on the insertion tube portion side is formed by an inclined surface. 5. The tube connection structure according to claim 4 , wherein the inclined surface of the outer tube portion is formed by an R chamfered surface. The tube connection structure according to any one of claims 1 to 5 , wherein the insertion tube portion is inserted inside an outer end of the protruding wall. The connection of the tubular body according to any one of claims 1 to 6 , wherein the first tubular body and the second tubular body are formed of any one of an aluminum alloy, copper, and a copper alloy. Construction. The tube connection structure according to any one of claims 1 to 7 , wherein the first tube body and the second tube body are joined to each other at a portion of the protruding wall by a brazed portion. The second tubular body includes the insertion tube portion in which only one end portion is inserted into the opening portion of the protruding wall, the outer tube portion communicating with the insertion tube portion and external to the protruding wall. The tube connection structure according to any one of claims 1 to 8 , wherein the tube connection structure is provided. A tube through which the refrigerant passes;
Laminating a plurality of fins, a core portion through which the tube penetrates each fin,
A header formed outside the core portion;
In the heat exchanger having the tube and the connecting pipe connected to the header,
The pipe connection structure of the header and the connection pipe is the first pipe body of the pipe connection structure according to any one of claims 1 to 9 , wherein the header is the second pipe. A heat exchanger in which the body is formed as said connecting tube. A tube through which the refrigerant passes;
Laminating a plurality of fins, a core portion through which the tube penetrates each fin,
A header formed outside the core portion;
In the heat exchanger having the tube and the connecting pipe connected to the header,
The connection structure of the pipe body between the header and the connection pipe is as follows:
In the connection structure of the tubular body that connects the first tubular body and the second tubular body,
The first tubular body has a protruding wall in which a part of the side wall protrudes outward to form an opening,
The second tube has an insertion tube portion whose end is inserted into the opening of the protruding wall, and an outer tube portion that communicates with the insertion tube portion and is external to the protruding wall.
The tube diameter of the outer tube portion is smaller than the tube diameter of the insertion tube portion, and is a connection structure of the tube body, wherein the first tube body of the tube connection structure is the header, A heat exchanger in which a two-pipe body is formed as the connecting pipe . The connection structure for the tube body of the heat exchanger according to claim 11, wherein an outer shape of the outer tube portion on the insertion tube portion side is formed by an inclined surface. The connection structure for the tubular body of the heat exchanger according to claim 12, wherein the inclined surface of the outer tube portion is formed by an R chamfered surface. The connection structure of the tube body of the heat exchanger according to any one of claims 11 to 13, wherein the insertion tube portion is inserted inside an outer end of the protruding wall. The connection structure for the tube of the heat exchanger according to any one of claims 11 to 14, wherein the first tube and the second tube are made of an aluminum alloy, copper, or a copper alloy. A heat exchanger formed of either. The connection structure for the tube of the heat exchanger according to any one of claims 11 to 15, wherein the first tube and the second tube are brazed at a portion of the protruding wall. Heat exchanger joined at The connection structure for the tube of the heat exchanger according to any one of claims 11 to 16, wherein the second tube has only one end inserted into the opening of the protruding wall. The heat exchanger having the insertion tube portion and the outer tube portion that communicates with the insertion tube portion and is external to the protruding wall.

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