Pipe fitting connecting structure and heat exchanger

Abstract

The utility model provides a pipe fitting connecting structure and a heat exchanger, and relates to the technical field of pipeline connection. The pipe fitting connecting structure comprises a connecting pipe and a first pipe fitting, the connecting pipe is of a hollow structure and comprises a limiting part and a connecting part which are connected with each other, and the diameter of the inner wall of the limiting part is larger than that of the inner wall of the connecting part; the first pipe fitting comprises a flaring part and a main body part which are connected with each other, the main body part coaxially penetrates through the connecting part and is connected with the connecting part, the flaring part is arranged in the limiting part, the outer wall diameter of the flaring part is larger than that of the connecting part, and the outer wall diameter of the flaring part is larger than that of the inner wall of the connecting part. As the diameter of the outer wall of the flaring part is larger than that of the inner wall of the connecting part, the connecting part cannot penetrate through the flaring part, limiting between the connecting pipe and the first pipe fitting is achieved, and the risk that in the high-pressure using process, the connector pops up relative to the first pipe fitting to cause damage to operators or equipment is prevented.

Description

Technical Field

[0001] The utility model generally relates to the technical field of pipeline connection, and in particular to a pipe connection structure and a heat exchanger. Background Art

[0002] In general production of heat exchangers, the inlet and outlet pipes are connected to the external pipeline through joints. Generally, the inlet and outlet pipes are matched with the joints with the same diameter. The joints are prone to falling off during use. Especially under high pressure, the joints may pop out quickly and cause harm to people and equipment, affecting the safety of use and user experience. Utility Model Content

[0003] The utility model provides a pipe connection structure and a heat exchanger, which increase the matching strength, play an explosion-proof role, and improve the safety of use.

[0004] According to a first aspect of the present invention, a pipe connection structure is provided, comprising:

[0005] A pipe having a hollow structure, comprising a limiting portion and a connecting portion connected to each other, wherein the inner wall diameter of the limiting portion is larger than the inner wall diameter of the connecting portion;

[0006] A first pipe fitting, the first pipe fitting includes a flared portion and a main body portion connected to each other, the main body portion is coaxially passed through the connecting portion and connected to the connecting portion, the flared portion is arranged in the limiting portion, the outer wall diameter of the flared portion is smaller than the outer wall diameter of the connecting portion, and the outer wall diameter of the flared portion is larger than the inner wall diameter of the connecting portion.

[0007] In some embodiments, the connecting pipe further includes a first transition portion, which is disposed between the limiting portion and the connecting portion and is connected to the limiting portion and the connecting portion respectively;

[0008] The first pipe also includes a second transition portion, which is arranged between the flared portion and the main body and connected to the flared portion and the main body respectively, and the second transition portion is arranged in the first transition portion and contacts the inner wall of the first transition portion.

[0009] In some embodiments, the inner wall of the first transition portion is a first conical structure, the small end of the first conical structure is arranged toward the connecting portion, and the large end of the first conical structure is arranged toward the limiting portion;

[0010] And / or, the outer wall of the second transition portion is a second conical structure, the small end of the second conical structure is arranged toward the connecting portion, and the large end of the second conical structure is arranged toward the limiting portion.

[0011] In some embodiments, the inner wall of the first transition portion is an arc-shaped structure;

[0012] And / or, the outer wall of the second transition portion is an arc-shaped structure.

[0013] In some embodiments, the outer wall diameters of the first transition portion, the outer wall diameters of the limiting portion, and the outer wall diameters of the connecting portion are the same, the wall thickness of the first transition portion is smaller than the wall thickness of the connecting portion, and the wall thickness of the first transition portion is greater than the wall thickness of the limiting portion.

[0014] In some embodiments, the wall thickness of the first transition portion is B, the wall thickness of the limiting portion is B1, and the wall thickness of the connecting portion is B2;

[0015] Among them, B≥4mm, 1.2 <B2 / B1≤4。

[0016] In some embodiments, along the axial direction of the connecting pipe, the length of the overlapping portion between the connecting portion and the main body is L1, and the length of the connecting portion is L;

[0017] Among them, 5mm≤L1≤20mm, L1≤L.

[0018] In some embodiments, the diameter of the flared portion is d1, and the diameter of the main body portion is d2;

[0019] Among them, 1.05≤d1 / d2≤1.25.

[0020] In some embodiments, a positioning portion is provided between one end of the connecting portion away from the limiting portion and the main body portion, and a positioning matching portion is provided at the other end corresponding to the positioning portion.

[0021] According to the second aspect of the present invention, an embodiment of the present invention further provides a heat exchanger including the above-mentioned pipe connection structure.

[0022] An embodiment of the present invention has the following advantages or beneficial effects:

[0023] In the pipe connection structure and heat exchanger provided by the embodiments of the present invention, since the inner diameters of the connecting pipes and the outer diameters of the first pipes are not identical, the smaller-diameter main body portion is correspondingly disposed within the smaller-diameter connecting portion, and the larger-diameter flared portion is correspondingly disposed within the larger-diameter limiting portion. When the connecting pipe moves away from the first pipe under the influence of air pressure, the connecting portion cannot pass through the flared portion because the outer diameter of the flared portion is larger than the inner diameter of the connecting portion. This achieves a position limit between the connecting pipe and the first pipe, preventing the risk of the joint popping out of the first pipe during high-pressure use, potentially causing damage to the operator or equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] To better understand the present invention, reference may be made to the embodiments shown in the following drawings. The components in the drawings are not necessarily to scale, and related elements may be omitted in order to emphasize and clearly illustrate the technical features of the present invention. In addition, related elements or components may have different arrangements as known in the art. In addition, in the drawings, the same reference numerals represent the same or similar components in each figure. The above and other features and advantages of the present invention will become more apparent by describing in detail its exemplary embodiments with reference to the accompanying drawings.

[0025] in:

[0026] Figure 1 Shown is a structural schematic diagram of a pipe connection structure according to an embodiment of the present invention;

[0027] Figure 2 The figure shows a schematic structural diagram of a pipe in a pipe connection structure according to an embodiment of the present invention;

[0028] Figure 3 Shown is a structural schematic diagram of the first pipe in the pipe connection structure of an embodiment of the present utility model.

[0029] The description of the accompanying drawings is as follows:

[0030] 1. Connect the pipe; 2. First pipe fitting;

[0031] 11. Limiting portion; 12. Connecting portion; 13. First transition portion;

[0032] 21. Flared portion; 22. Main body; 23. Second transition portion. DETAILED DESCRIPTION

[0033] The following will be combined with the accompanying drawings in the exemplary embodiments of the present invention to clearly and completely describe the technical solutions in the exemplary embodiments of the present invention. The exemplary embodiments described herein are for illustrative purposes only and are not intended to limit the scope of protection of the present invention. Therefore, it should be understood that various modifications and changes can be made to the exemplary embodiments without departing from the scope of protection of the present invention.

[0034] In the description of the present invention, unless otherwise expressly provided or limited, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance; the term "plurality" refers to two or more; and the term "and / or" includes any and all combinations of one or more of the associated listed items. In particular, reference to "the" or "an" object is also intended to mean one of a possible plurality of such objects.

[0035] Unless otherwise specified or explained, the terms "connect," "fixed," etc. should be understood broadly. For example, "connected" may refer to a fixed connection, a detachable connection, an integral connection, an electrical connection, or a signal connection; and "connected" may refer to a direct connection or an indirect connection through an intermediary. Those skilled in the art will understand the specific meanings of the above terms in this utility model based on specific circumstances.

[0036] Furthermore, in the description of the present invention, it should be understood that the directional words such as "upper", "lower", "inside", and "outside" described in the exemplary embodiments of the present invention are described based on the angles shown in the accompanying drawings and should not be understood as limiting the exemplary embodiments of the present invention. It should also be understood that, in the context, when it is mentioned that an element or feature is connected to another element (one or more) "upper", "lower", or "inside", "outside", it can not only be directly connected to the other (one or more) elements "upper", "lower", or "inside", "outside", but can also be indirectly connected to the other (one or more) elements "upper", "lower", "inside", "outside" through an intermediate element.

[0037] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be implemented in many forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete and will fully convey the concepts of the example embodiments to those skilled in the art. Like reference numerals in the figures represent like or similar structures, and thus their detailed description will be omitted.

[0038] This embodiment provides a pipe connection structure, such as Figure 1 As shown, the pipe connection structure includes a connecting pipe 1 and a first pipe 2. The connecting pipe 1 can also be called a joint. The connecting pipe 1 is a hollow structure. The first pipe 2 is inserted into the inner cavity of the connecting pipe 1. The connecting pipe 1 is used to fix and install the first pipe 2.

[0039] If the inner diameter of the connecting pipe 1 at any position is exactly the same, and the outer diameter of the first pipe 2 at any position is exactly the same, the connecting pipe 1 is likely to fall off during use. Under high pressure, the connecting pipe 1 may pop out quickly and cause harm to people and equipment, affecting safety of use and user experience.

[0040] For this reason, Figure 1-Figure 3As shown, the connecting pipe 1 provided in this embodiment includes a stopper portion 11 and a connecting portion 12 connected to each other. The inner wall diameter of the stopper portion 11 is larger than the inner wall diameter of the connecting portion 12. The first pipe fitting 2 includes a flared portion 21 and a main body portion 22 connected to each other. The main body portion 22 is coaxially arranged through and connected to the connecting portion 12. The flared portion 21 is disposed within the stopper portion 11. The outer wall diameter of the flared portion 21 is smaller than the outer wall diameter of the connecting portion 12, and the outer wall diameter of the flared portion 21 is larger than the inner wall diameter of the connecting portion 12. It is used to limit the position between the connecting pipe 1 and the first pipe fitting 2.

[0041] In the pipe connection structure provided in this embodiment, since the inner wall diameters of the connecting pipe 1 and the outer wall diameters of the first pipe 2 are not identical, the smaller-diameter main body portion 22 is correspondingly disposed within the smaller-diameter connecting portion 12, and the larger-diameter flared portion 21 is correspondingly disposed within the larger-diameter limiting portion 11. When the connecting pipe 1 moves away from the first pipe 2 under the influence of air pressure, etc., the connecting portion 12 cannot pass through the flared portion 21 because the outer wall diameter of the flared portion 21 is larger than the inner wall diameter of the connecting portion 12. This limits the position between the connecting pipe 1 and the first pipe 2, preventing the connecting pipe 1 from ejecting relative to and away from the first pipe 2 under high-pressure conditions, thereby reducing the risk of damage to operators or equipment.

[0042] At the same time, the main body 22 is coaxially penetrated by the connecting portion 12 and connected to the connecting portion 12, and the connection between the connecting portion 12 and the first pipe fitting 2 is realized, thereby increasing the connection reliability between the connecting pipe 1 and the first pipe fitting 2 and further reducing the risk of the connecting pipe 1 popping out.

[0043] During installation, the end of the main body 22 of the first pipe fitting 2 away from the flared portion 21 is moved from the limiting portion 11 of the pipe fitting 1 toward the connecting portion 12 along the axial direction of the pipe 1 until the flared portion 21 of the first pipe fitting 2 moves to a position where the limiting portion 11 is close to the connecting portion 12. The limiting portion 11 and the flared portion 21 also play a role in installation positioning. Then, the connecting portion 12 and the main body 22 are connected. The structure is simple, the installation is convenient, and the production cost is relatively low.

[0044] Among them, the portion of the main body 22 extending into the connecting portion 12 has an interference fit or a clearance fit with the connecting portion 12. When the main body 22 has an interference fit with the connecting portion 12, it is beneficial to improve the connection strength between the connecting pipe 1 and the first pipe fitting 2. When the main body 22 has a clearance fit with the connecting portion 12, if the connecting pipe 1 and the first pipe fitting 2 are welded, the solder can penetrate into the gap between the main body 22 and the connecting portion 12. The welding layer formed after welding can also improve the connection strength between the connecting pipe 1 and the first pipe fitting 2, and is also beneficial to the docking assembly of the main body 22 and the connecting portion 12. The portion of the main body 22 extending into the connecting portion 12 has an interference fit or a clearance fit with the connecting portion 12, which is beneficial to improve the connection strength between the first pipe fitting 2 and the connecting pipe 1.

[0045] It can be understood that the connection portion 12 is provided at one end of the pipe 1 along the axial direction of the pipe 1 , that is, the connection portion 12 is provided at an outer side of the pipe 1 to facilitate the operator to perform welding operations.

[0046] If the length of the overlapping portion between the connecting portion 12 and the main body 22 is less than or equal to 5 mm, the length of the overlapping portion between the connecting portion 1 and the first pipe fitting 2 is too short, and insufficient connection strength may occur; if the length of the overlapping portion between the connecting portion 12 and the main body 22 is greater than or equal to 20 mm, the length of the overlapping portion between the connecting portion 1 and the first pipe fitting 2 is too long, resulting in a longer welding length, wasting solder material, and also risking serious deformation.

[0047] For this reason, Figure 1-Figure 3 As shown, along the axial direction of the pipe 1, the length of the overlapping portion between the connecting portion 12 and the main body 22 is L1, wherein 5mm≤L1≤20mm. For example, L1 can be 5mm, 10mm, 15mm, or 20mm.

[0048] In this way, the length L1 of the overlapping portion between the connecting portion 12 and the main body 22 is limited to a range between 5 mm and 20 mm, which meets the welding strength between the connecting portion 12 and the main body 22 and improves the connection firmness. At the same time, the welding length is appropriate to reduce the risk of solder material and deformation.

[0049] The length of the connecting portion 12 is L, L1≤L. That is, the overlap between the connecting portion 12 and the main body 22 does not exceed the length range of the connecting portion 12, thereby preventing solder overflow from affecting the appearance quality.

[0050] In one embodiment, the outer wall of the flared portion 21 contacts the inner wall of the limiting portion 11. That is, the outer wall of the flared portion 21 and the inner wall of the limiting portion 11 are adapted to fit as closely as possible, thereby reducing the occurrence of abnormal noise during use.

[0051] Of course, in some other embodiments, there may be a certain gap between the outer wall of the flared portion 21 and the inner wall of the limiting portion 11 , as long as the flared portion 21 can be installed in the limiting portion 11 .

[0052] If the diameter of the flared portion 21 is too large and the diameter of the main body 22 is too small, the diameter difference of the first pipe fitting 2 as a whole is large, and cracks are likely to appear between the main body 22 and the flared portion 21; however, if the diameter difference between the flared portion 21 and the main body 22 of the first pipe fitting 2 is small, it is not conducive to the need for limiting.

[0053] In one embodiment, Figure 1-Figure 3As shown, the diameter of the flared portion 21 is d1, and the diameter of the main body portion 22 is d2. Here, 1.05≤d1 / d2≤1.25.

[0054] In this way, the ratio between the diameter d1 of the flared portion 21 and the diameter d2 of the main body 22 is limited to the range of 1.05 and 1.25, reducing the risk of cracks between the main body 22 and the flared portion 21 and improving the firmness and stability of the assembly.

[0055] In one embodiment, Figure 1-Figure 3 As shown, the connecting pipe 1 also includes a first transition portion 13, which is arranged between the limiting portion 11 and the connecting portion 12 and is connected to the limiting portion 11 and the connecting portion 12 respectively. While the first transition portion 13 realizes the intermediate connection between the limiting portion 11 and the connecting portion 12, the first transition portion 13 also plays a role of transition between the limiting portion 11 and the connecting portion 12.

[0056] The outer wall of the first transition portion 13, the outer wall of the limiting portion 11 and the outer wall of the connecting portion 12 have the same diameter, that is, the outer shape of the connecting pipe 1 is similar to a cylindrical structure, and the appearance of the connecting pipe 1 is consistent.

[0057] The inner wall of the first transition portion 13 is an arc-shaped structure. Since the inner wall of the first transition portion 13 has an arc surface, it avoids the situation where the inner wall of the connection position between the limiting portion 11 and the connecting portion 12 has sharp corners and damages to the first pipe 2.

[0058] In one embodiment, the inner wall of the first transition portion 13 is a first conical structure, the small end of the first conical structure is arranged toward the connecting portion 12 , and the large end of the first conical structure is arranged toward the limiting portion 11 .

[0059] That is, the first transition portion 13 is essentially a tapered structure. Along the axial direction of the connecting pipe 1 and from the flared portion 21 to the main portion 22, the cross-sectional area of ​​the first transition portion 13 gradually decreases, achieving a gradual and uniform transition between the stopper portion 11 and the connecting portion 12. Furthermore, with this approach, the inner wall of the first transition portion 13 also serves as a guide, facilitating the guidance of the main portion 22 of the first pipe 2 to the connecting portion 12.

[0060] The wall thickness of the first transition portion 13 is smaller than that of the connecting portion 12. Since the connecting portion 12 is located at the connection position between the connecting pipe 1 and the first pipe 2, the thicker wall thickness of the connecting portion 12 increases the connection strength between the connecting pipe 1 and the first pipe 2, further preventing the risk of welding deformation.

[0061] The wall thickness of the first transition portion 13 is greater than the wall thickness of the limiting portion 11 , thereby achieving a transition between the wall thickness of the limiting portion 11 and the wall thickness of the connecting portion 12 .

[0062] For example, the wall thickness of the first transition portion 13 is B, the wall thickness of the limiting portion 11 is B1, and the wall thickness of the connecting portion 12 is B2. <B2 / B1≤4。

[0063] By setting B2 / B1 to be greater than 1.2, the structural strength of the connecting portion 12 is enhanced, which is beneficial to increasing the matching strength between the connecting portion 12 and the main body 22. At the same time, it is effectively avoided that the span of the first transition portion 13 is too small, which is not conducive to the limitation between the connecting pipe 1 and the first pipe fitting 2; by setting B2 / B1 to be less than or equal to 4, stress concentration in the first transition portion 13 is effectively prevented.

[0064] In one embodiment, the first pipe member 2 further includes a second transition portion 23, which is disposed between the flared portion 21 and the main portion 22 and connected to the flared portion 21 and the main portion 22, respectively. The second transition portion 23 is disposed within the first transition portion 13 and contacts the inner wall of the first transition portion 13. While the second transition portion 23 achieves an intermediate connection between the flared portion 21 and the main portion 22, the first transition portion 13 also serves as a transition between the flared portion 21 and the main portion 22.

[0065] In one embodiment, the outer wall of the second transition portion 23 is a second conical structure, the small end of the second conical structure is arranged toward the connecting portion 12 , and the large end of the second conical structure is arranged toward the limiting portion 11 .

[0066] That is, the second transition portion 23 is essentially a tapered structure. Along the axial direction of the connecting pipe 1 and from the flared portion 21 to the main body 22, the cross-sectional area of ​​the second transition portion 23 gradually decreases, achieving a gradual and uniform transition from the flared portion 21 to the main body 22. Furthermore, this approach, through the cooperation of the inner wall of the first transition portion 13 and the outer wall of the second transition portion 23, also achieves a guiding effect, facilitating the installation between the first pipe 2 and the connecting pipe 1.

[0067] The outer wall of the second transition portion 23 is an arc-shaped structure. Since the outer wall of the second transition portion 23 has an arc surface, it avoids the situation where the connecting position between the flared portion 21 and the main body 22 has sharp corners and damages to the pipe 1.

[0068] In one embodiment, a positioning portion (not shown in the figure) is provided between one end of the connecting portion 12 away from the limiting portion 11 and the main body 22, and a positioning matching portion (not shown in the figure) is provided on the other corresponding positioning portion.

[0069] The positioning portion and the positioning engagement portion ensure positioning between the connecting pipe 1 and the first pipe 2, preventing displacement between the connecting pipe 1 and the first pipe 2. Furthermore, the positioning portion is located at the end of the connecting portion 12 away from the limiting portion 11, thereby preventing the connecting pipe 1 from popping out toward the main body 22.

[0070] It should be noted that the positioning portion and the positioning matching portion must not affect the installation between the connecting pipe 1 and the first pipe 2. For example, the positioning matching portion can be a first groove and a second groove provided on the inner wall of the connecting pipe 1, with the first groove extending along the axial direction of the connecting pipe 1 and the first groove and the second groove being perpendicular to each other to form an L-shaped structure. The positioning portion is a protrusion provided on the first pipe 2. During installation, the protrusion slides along the first groove, serving as a guide between the connecting pipe 1 and the first pipe 2. After installation is complete, the first pipe 2 is rotated to rotate the protrusion into the second groove, thereby serving as a positioning function between the connecting pipe 1 and the first pipe 2.

[0071] In one embodiment, the pipe connection structure also includes a second pipe (not shown in the figure), which is sleeved on the end of the connecting pipe 1 away from the first pipe 2 and connected to the connecting pipe 1, so that the first pipe 2 is connected to the second pipe through the connecting pipe 1, thereby realizing the connection between the two pipes.

[0072] Specifically, the inner wall of the second pipe is provided with an internal thread, the outer wall of the connecting pipe 1 is provided with an external thread, and the internal thread of the second pipe is connected to the external thread of the connecting pipe 1 to achieve a detachable connection between the second pipe and the connecting pipe 1.

[0073] The outer wall of the connecting pipe 1 may be provided with a positioning platform, and the second pipe may abut against the positioning platform to achieve positioning between the second pipe and the connecting pipe 1 during installation.

[0074] This embodiment also provides a heat exchanger including a pipe connection structure. Because the inner wall diameters of the connecting pipe 1 and the outer wall diameters of the first pipe 2 are not identical, the main body portion 22 with a smaller diameter is correspondingly disposed within the connecting portion 12 with a smaller diameter, and the flared portion 21 with a larger diameter is correspondingly disposed within the limiting portion 11 with a larger diameter. When the connecting pipe 1 moves away from the first pipe 2 under the influence of air pressure or the like, the connecting portion 12 cannot pass through the flared portion 21 because the outer wall diameter of the flared portion 21 is larger than the inner wall diameter of the connecting portion 12. This achieves a position limit between the connecting pipe 1 and the first pipe 2, preventing the connecting pipe 1 from ejecting relative to and away from the first pipe 2 under high pressure, thereby reducing the risk of damage to operators or equipment.

[0075] It should be noted that the embodiments of the present invention are shown in the drawings and described in this specification is only an example of the principles of the present invention. It should be clear to those skilled in the art that the principles of the present invention are not limited to any details or any components of the devices shown in the drawings or described in the specification.

[0076] It should be understood that the present invention is not limited in its application to the detailed structure and arrangement of the components proposed in this specification. The present invention is capable of other embodiments and can be implemented and executed in a variety of ways. The aforementioned variations and modifications fall within the scope of the present invention. It should be understood that the present invention disclosed and defined in this specification extends to all alternative combinations of two or more individual features mentioned or apparent in the text and / or the drawings. All of these different combinations constitute multiple alternative aspects of the present invention. The embodiments described in this specification illustrate the best known ways to implement the present invention and will enable those skilled in the art to utilize the present invention.

[0077] Other embodiments of the present invention will readily occur to those skilled in the art after considering this specification and practicing the invention disclosed herein. This invention is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein. The description and example embodiments are to be considered as exemplary only, with the true scope and spirit of the invention being indicated by the appended claims.

[0078] It should be understood that the present invention is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of protection of the present invention is limited only by the appended claims.

Claims

1. A pipe connection structure, characterized in that: include: A pipe (1), the pipe (1) being a hollow structure, comprising a limiting portion (11) and a connecting portion (12) connected to each other, wherein the inner wall diameter of the limiting portion (11) is greater than the inner wall diameter of the connecting portion (12); A first pipe fitting (2), comprising a flared portion (21) and a main body (22) connected to each other, wherein the main body (22) is coaxially arranged in the connecting portion (12) and connected to the connecting portion (12), the flared portion (21) is arranged in the limiting portion (11), the outer wall diameter of the flared portion (21) is smaller than the outer wall diameter of the connecting portion (12), and the outer wall diameter of the flared portion (21) is larger than the inner wall diameter of the connecting portion (12).

2. The pipe connection structure according to claim 1, characterized in that: The connecting pipe (1) further includes a first transition portion (13), which is arranged between the limiting portion (11) and the connecting portion (12) and is connected to the limiting portion (11) and the connecting portion (12) respectively; The first pipe (2) further includes a second transition portion (23), the second transition portion (23) being arranged between the flared portion (21) and the main body (22) and being connected to the flared portion (21) and the main body (22) respectively, and the second transition portion (23) being arranged inside the first transition portion (13) and in contact with the inner wall of the first transition portion (13).

3. The pipe connection structure according to claim 2, characterized in that: The inner wall of the first transition portion (13) is a first conical structure, the small end of the first conical structure is arranged toward the connecting portion (12), and the large end of the first conical structure is arranged toward the limiting portion (11); And / or, the outer wall of the second transition portion (23) is a second conical structure, the small end of the second conical structure is arranged toward the connecting portion (12), and the large end of the second conical structure is arranged toward the limiting portion (11).

4. The pipe connection structure according to claim 2, characterized in that: The inner wall of the first transition portion (13) is an arc-shaped structure; And / or, the outer wall of the second transition portion (23) is an arc-shaped structure.

5. The pipe connection structure according to claim 2, characterized in that: The outer wall diameter of the first transition portion (13), the outer wall diameter of the limiting portion (11), and the outer wall diameter of the connecting portion (12) are the same; the wall thickness of the first transition portion (13) is smaller than the wall thickness of the connecting portion (12); and the wall thickness of the first transition portion (13) is greater than the wall thickness of the limiting portion (11).

6. The pipe connection structure according to claim 5, characterized in that: The wall thickness of the first transition portion (13) is B, the wall thickness of the limiting portion (11) is B1, and the wall thickness of the connecting portion (12) is B2; Among them, B≥4mm, 1.2 <B2 / B1≤4。 7. The pipe connection structure according to any one of claims 1 to 6, characterized in that: Along the axial direction of the connecting pipe (1), the length of the overlapping portion between the connecting portion (12) and the main body (22) is L1, and the length of the connecting portion (12) is L; Among them, 5mm≤L1≤20mm, L1≤L.

8. The pipe connection structure according to any one of claims 1 to 6, characterized in that: The diameter of the flared portion (21) is d1, and the diameter of the main body portion (22) is d2; Among them, 1.05≤d1 / d2≤1.

25.

9. The pipe connection structure according to any one of claims 1 to 6, characterized in that: A positioning portion is provided between one end of the connecting portion (12) away from the limiting portion (11) and the main body portion (22), and a positioning matching portion is provided at the other end corresponding to the positioning portion.

10. A heat exchanger, characterized in that: The invention comprises the pipe connection structure according to any one of claims 1 to 9.

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