Refrigeration system connection pipe structure

Abstract

This utility model relates to the field of connection structures, specifically to a connecting pipe structure for a refrigeration system, including connecting fittings and a copper-steel composite connecting pipe. One end of the connecting fitting is connected to the refrigeration system, and the other end of the connecting fitting abuts, sleeves, or inserts into the copper-steel composite connecting pipe. The copper-steel composite connecting pipe includes at least a steel layer and a copper layer arranged sequentially from the inside out. This refrigeration system connecting pipe structure, by welding the copper-steel composite connecting pipe and the connecting fitting, combines the excellent weldability and corrosion resistance of copper with the high strength and low cost of steel, resulting in superior overall performance.

Description

Technical Field

[0001] This utility model relates to the field of connection structures, specifically to a connection pipe structure for a refrigeration system. Background Technology

[0002] Currently, air conditioning compressors and receiver-operated pipes are made of steel, aluminum, or stainless steel. These pipes are brazed to ensure the airtightness of the entire refrigeration system. Copper pipes offer excellent weldability, machinability, and corrosion resistance, but their high cost limits their application in low-cost designs. Aluminum pipes offer a significant cost advantage, are easy to process, and have excellent corrosion resistance, but welding them is difficult, requiring expensive silver solder, resulting in inconsistent weld quality, a high risk of leakage, and ultimately, higher overall costs. Stainless steel pipes offer high strength, excellent corrosion resistance, and low cost, but they are difficult to process, have poor weldability, require highly skilled welders, and also suffer from inconsistent weld quality and a high risk of leakage.

[0003] In summary, the welding of currently used aluminum or stainless steel pipes to connecting piping presents significant technological challenges, making it difficult to guarantee welding reliability. While pure copper pipes offer excellent performance, their cost is high. Therefore, there is an urgent need for a connecting pipe structure that combines excellent welding performance, processing performance, corrosion resistance, and reasonable cost to solve the problems in existing technologies. Summary of the Invention

[0004] In order to overcome the shortcomings and deficiencies of the existing technology, the purpose of this utility model is to provide a connecting pipe structure for a refrigeration system. By using copper-steel composite connecting pipes and connecting accessories for welding, it combines the advantages of copper's excellent welding performance and corrosion resistance with the advantages of steel's high strength and low cost, resulting in superior overall performance.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0006] A refrigeration system connecting pipe structure includes a connecting fitting and a copper-steel composite connecting pipe. One end of the connecting fitting is connected to the refrigeration system, and the other end of the connecting fitting abuts, sleeves, or inserts into the copper-steel composite connecting pipe. The copper-steel composite connecting pipe includes at least a steel layer and a copper layer arranged sequentially from the inside to the outside.

[0007] Furthermore, the refrigeration system includes an air conditioning compressor and a liquid receiver, wherein the connecting fittings of the compressor abut, sleeve, or insert into the copper-steel composite connecting pipe, and the connecting fittings of the liquid receiver abut, sleeve, or insert into the copper-steel composite connecting pipe.

[0008] Furthermore, the copper-steel composite connecting pipe includes a copper layer, a steel layer, and another copper layer arranged sequentially from the inside out.

[0009] Furthermore, the end of the connecting fitting away from the refrigeration system is provided with a first sealing surface, and the end of the copper-steel composite connecting pipe near the connecting fitting is provided with a second sealing surface that fits against the first sealing surface.

[0010] Furthermore, the end of the connecting fitting away from the refrigeration system is provided with an expanding section or a reducing section. The expanding section is sleeved on the copper-steel composite connecting pipe, and the outer wall of the copper-steel composite connecting pipe is attached to the inner wall of the expanding section. Alternatively, the reducing section is inserted into the copper-steel composite connecting pipe, and the inner wall of the copper-steel composite connecting pipe is attached to the outer wall of the reducing section.

[0011] Furthermore, one end of the copper-steel composite connecting pipe is provided with an enlarged diameter section or a reduced diameter section. The enlarged diameter section is sleeved on the connecting fitting, and the outer wall of the connecting fitting is attached to the inner wall of the enlarged diameter section. Alternatively, the reduced diameter section is inserted into the connecting fitting, and the inner wall of the connecting fitting is attached to the outer wall of the reduced diameter section.

[0012] Furthermore, the end of the connecting fitting away from the refrigeration system is provided with an expansion section or a reduction section, and the end of the copper-steel composite connecting pipe is provided with a reduction section or an expansion section. The expansion section is sleeved on the reduction section, and the inner wall of the expansion section is attached to the outer wall of the reduction section.

[0013] Furthermore, the expanding section includes a gradually expanding section and a first connecting section arranged sequentially along the end edge of the copper-steel composite connecting pipe or connecting fitting, and the reducing section includes a gradually reducing section and a second connecting section arranged sequentially along the end edge of the copper-steel composite connecting pipe or connecting fitting; the first connecting section is sleeved on the second connecting section, connecting fitting or copper-steel composite connecting pipe, and the second connecting section is inserted into the first connecting section, connecting fitting or copper-steel composite connecting pipe.

[0014] Furthermore, the steel layer is a stainless steel layer or a low-carbon steel layer, and the copper layer is a copper layer.

[0015] Furthermore, the area where the connecting fitting and the copper-steel composite connecting pipe are in contact is not provided with a copper layer.

[0016] Furthermore, the connecting fittings are welded to the copper-steel composite connecting pipe using laser welding, carbon dioxide shielded welding, ion welding, high-frequency welding, or argon arc welding.

[0017] The beneficial effects of this utility model are as follows: The refrigeration system connecting pipe structure of this utility model, through the welding of copper-steel composite connecting pipes and connecting fittings, combines the advantages of copper's excellent welding performance and corrosion resistance with the advantages of steel's high strength and low cost, resulting in superior overall performance. The inner steel layer of the copper-steel composite connecting pipe provides high strength, ensuring the mechanical properties of the connecting pipe, while the outer copper layer provides excellent corrosion resistance. Compared to pure copper pipes, the copper-steel composite connecting pipe reduces the amount of copper used, lowering material costs; compared to aluminum or stainless steel pipes, its welding process is simpler, requiring no high-cost solder or highly skilled welders, resulting in lower overall manufacturing costs. The copper-steel composite connecting pipe and connecting fittings are physically connected through sleeve, plug, or abutment joints, and combined with the easy weldability of the copper layer, a highly airtight weld can be formed. This utility model solves the problems of difficult welding of existing pure aluminum and pure stainless steel pipes, and the high cost of pure copper pipes, achieving a balance between performance, reliability, and economy. Attached Figure Description

[0018] Figure 1 This is a longitudinal section view of the copper-steel composite connecting pipe.

[0019] Figure 2 This is a schematic diagram of the connecting pipe structure of the refrigeration system in Example 1.

[0020] Figure 3 This is a longitudinal section sectional view of the expanded diameter section.

[0021] Figure 4 This is a schematic diagram of the connecting pipe structure of the refrigeration system in Example 2.

[0022] Figure 5 This is a longitudinal section sectional view of the reduced diameter section.

[0023] Figure 6 This is a schematic diagram of the connecting pipe structure of the refrigeration system in Example 3.

[0024] Figure 7 This is a schematic diagram of the connecting pipe structure of the refrigeration system in Example 4.

[0025] Figure 8 This is a schematic diagram of the connecting pipe structure of the refrigeration system in Example 5.

[0026] Figure 9 This is a schematic diagram of the connecting pipe structure of the refrigeration system in Example 6.

[0027] Figure 10 This is a schematic diagram of the connecting pipe structure of the refrigeration system in Example 7.

[0028] The reference numerals in the figures include:

[0029] 1. Connecting fittings; 11. First sealing surface; 2. Copper-steel composite connecting pipe; 21. Steel layer; 22. Copper layer; 23. Second sealing surface; 3. Expanding section; 31. Gradual expansion section; 32. First connecting section; 4. Reducing section; 41. Gradual reduction section; 42. Second connecting section. Detailed Implementation

[0030] To facilitate understanding by those skilled in the art, the present invention will be further described below with reference to embodiments and accompanying drawings. The content mentioned in the embodiments is not intended to limit the present invention.

[0031] like Figure 1 As shown, a refrigeration system connecting pipe structure includes a connecting fitting 1 and a copper-steel composite connecting pipe 2. One end of the connecting fitting 1 is connected to the refrigeration system, and the other end of the connecting fitting 1 abuts, sleeves, or inserts into the copper-steel composite connecting pipe 2. The copper-steel composite connecting pipe 2 includes at least a steel layer 21 and a copper layer 22 arranged sequentially from the inside to the outside.

[0032] This utility model discloses a refrigeration system connecting pipe structure that combines the advantages of copper (excellent welding performance and corrosion resistance) with steel (high strength and low cost) by welding a copper-steel composite connecting pipe 2 to connecting fittings 1, resulting in superior overall performance. Specifically, the inner steel layer 21 of the copper-steel composite connecting pipe 2 provides high strength, ensuring the mechanical properties of the connecting pipe, such as compressive strength and deformation resistance, while the outer copper layer 22 provides excellent corrosion resistance, making it particularly suitable for humid and refrigerant-corrosion environments in refrigeration systems. Compared to pure copper pipes, the copper-steel composite connecting pipe 2 reduces the amount of copper used, lowering material costs. Compared to aluminum or stainless steel pipes, its welding process is simpler, requiring no high-cost solder (such as silver solder) or highly skilled welders, resulting in lower overall manufacturing costs. Furthermore, the copper layer 22 is easy to bend and flare, facilitating on-site installation, while the steel layer 21 provides structural support, avoiding the deformation disadvantage of pure copper pipes. The copper-steel composite connecting pipe 2 and the connecting fitting 1 are physically connected by sleeve, plug, or abutment. Combined with the easy solderability of the copper layer 22, a highly airtight weld can be formed, significantly reducing the risk of refrigerant leakage in the refrigeration system. This utility model solves the problems of difficult welding of existing pure aluminum pipes and pure stainless steel pipes, as well as the high cost of pure copper pipes, achieving a balance between performance, reliability, and economy.

[0033] Furthermore, the refrigeration system includes an air conditioning compressor and a liquid receiver. When the compressor's connecting fitting 1 abuts, sleeves, or inserts into the copper-steel composite connecting pipe 2, the copper-steel composite connecting pipe 2 includes a copper layer, a steel layer 21, and a copper layer 22 arranged sequentially from the inside to the outside. That is, a copper layer is added inside the steel layer 21 to facilitate the insertion and welding of the connecting pipe inside. When the liquid receiver's connecting fitting 1 abuts, sleeves, or inserts into the copper-steel composite connecting pipe 2, the copper-steel composite connecting pipe 2 includes a steel layer 21 and a copper layer 22 arranged sequentially from the inside to the outside. The corresponding copper-steel composite connecting pipe 2 can be selected according to the requirements, and it has a wide range of applications.

[0034] Furthermore, the copper-steel composite connecting pipe 2 is manufactured by rolling the copper layer 22 and the steel layer 21 according to the required layers, and then stamping and stretching them. The copper layer 22 in the copper-steel composite connecting pipe 2 has a thickness of 35-60μm, and the steel layer 21 has a thickness of 0.8-1.5mm. The thickness of the copper layer 22 and the steel layer 21 before stamping and stretching is 20-30% thicker than that after stamping and stretching. The process is simple.

[0035] Furthermore, the area where the connecting fitting 1 and the copper-steel composite connecting pipe 2 are in contact with each other does not have a copper layer 22. That is, the steel layer 21 of the connecting fitting 1 and the copper-steel composite connecting pipe 2 are in contact with each other. The connecting fitting 1 is made of stainless steel or copper-plated steel, and the contact area is a steel-to-steel contact, which can improve the connection strength between the connecting fitting 1 and the copper-steel composite connecting pipe 2.

[0036] Furthermore, the steel layer 21 is a stainless steel layer or a low-carbon steel layer, wherein the stainless steel layer is made of 304 or 301, and the low-carbon steel layer is made of SPCC or SPCE; the copper layer 22 is a copper layer, wherein the copper layer is made of T2.

[0037] Furthermore, the connecting fitting 1 and the copper-steel composite connecting pipe 2 are welded together using laser welding, which helps to improve the weld strength. Specifically, the area where the copper-steel composite connecting pipe 2 is welded to the connecting fitting 1 does not have a copper layer 22. That is, after removing the outer copper layer 22, the laser welding only acts on the inner steel layer 21, avoiding the high reflectivity of the copper layer 22 to the laser and improving energy utilization. Moreover, the connecting fitting 1 is made of stainless steel or copper-plated steel, and the laser welding directly forms a fusion weld between the connecting fitting 1 and the steel layer 21 of the copper-steel composite connecting pipe 2. The weld is a steel-steel bond, avoiding the formation of brittle copper-iron phases and significantly improving the joint strength.

[0038] Furthermore, the specific steps for laser welding the connecting fitting 1 to the copper-steel composite connecting pipe 2 are as follows:

[0039] (1) Remove the copper layer from the copper-steel composite connecting pipe 2 in part;

[0040] (2) Assembly and positioning: Connect the copper-steel composite connecting pipe 2 and the connecting fitting 1 by abutting, sleeve or plugging as required.

[0041] (3) Laser welding is performed on the connection between the connecting fitting 1 and the copper-steel composite connecting pipe 2, wherein the laser power is 400-900W, the welding speed is 5-10mm / s, the laser focal length is 15-25mm, the spot diameter is 2-2.4mm, and the laser beam incident angle is 41°-49°.

[0042] Furthermore, in step (3), for low-pressure systems (≤6.9MPa), wireless self-fusion welding is selected; for medium- and high-pressure systems (6.9-25MPa), filler wire laser welding is selected to increase the penetration depth. The filler wire used is Cr with a diameter of 0.5-2mm. 12 MoV, with a wire feeding speed of 75-85 mm / min.

[0043] Furthermore, in step (3), after the laser welding completes one revolution, the laser head continues to travel along the original trajectory for 3-5mm to ensure consistent weld depth at the arc initiation and termination points.

[0044] Furthermore, the connecting fitting 1 and the copper-steel composite connecting pipe 2 are also welded by carbon dioxide shielded welding, ion welding, high-frequency welding or argon arc welding. Among them, carbon dioxide shielded welding, ion welding, high-frequency welding and argon arc welding are existing welding methods, and the corresponding welding method can be selected according to the requirements.

[0045] Example 1

[0046] like Figure 2 As shown, in this embodiment, the end of the connecting accessory 1 furthest from the refrigeration system is provided with a first sealing surface 11, and the end of the copper-steel composite connecting pipe 2 near the connecting accessory 1 is provided with a second sealing surface 23 that fits against the first sealing surface 11, thus achieving contact between the connecting accessory 1 and the copper-steel composite connecting pipe 2, making connection convenient. During laser welding, the welding point is located on the outer side of the copper-steel composite connecting pipe 2 near the second sealing surface 23.

[0047] Example 2

[0048] like Figure 3-4 As shown, in this embodiment, the end of the connecting fitting 1 away from the refrigeration system is provided with an enlarged diameter section 3, the enlarged diameter section 3 is sleeved on the copper-steel composite connecting pipe 2, and the outer wall of the copper-steel composite connecting pipe 2 is attached to the inner wall of the enlarged diameter section 3.

[0049] Furthermore, the outer wall area of ​​the copper-steel composite connecting pipe 2, which is attached to the inner wall of the expanded diameter section 3, does not have a copper layer 22.

[0050] Furthermore, the expanding section 3 includes a gradually expanding section 31 and a first connecting section 32 arranged sequentially along the end edge of the connecting fitting 1. The first connecting section 32 is sleeved onto the copper-steel composite connecting pipe 2. The longitudinal section of the gradually expanding section 31 is an isosceles trapezoid, and its diameter gradually increases outward along the end of the connecting fitting 1. The welding point is located on the outer side of the copper-steel composite connecting pipe 2 near the first connecting section 32, increasing the weld penetration.

[0051] Example 3

[0052] like Figure 5-6 As shown, in this embodiment, the end of the connecting accessory 1 away from the refrigeration system is provided with a reduced diameter section 4. The reduced diameter section 4 is inserted into the copper-steel composite connecting pipe 2, and the inner wall of the copper-steel composite connecting pipe 2 is attached to the outer wall of the reduced diameter section 4, making the connection convenient.

[0053] Furthermore, the reduced-diameter section 4 includes a tapered section 41 and a second connecting section 42 arranged sequentially along the end edge of the connecting fitting 1. The second connecting section 42 is inserted into the copper-steel composite connecting pipe 2. The longitudinal section of the tapered section 41 is an isosceles trapezoid, and its diameter gradually decreases outward along the end of the connecting fitting 1. The welding point is located on the outer side of the copper-steel composite connecting pipe 2 near the tapered section 41, increasing the weld penetration.

[0054] Example 4

[0055] like Figure 7 As shown, in this embodiment, one end of the copper-steel composite connecting pipe 2 is provided with an enlarged diameter section 3. The enlarged diameter section 3 is sleeved on the connecting fitting 1, and the outer wall of the connecting fitting 1 is attached to the inner wall of the enlarged diameter section 3, making the connection convenient.

[0056] Furthermore, the expanding section 3 includes a gradually expanding section 31 and a first connecting section 32 arranged sequentially along the end edge of the copper-steel composite connecting pipe 2, with the first connecting section 32 sleeved onto the connecting fitting 1. The longitudinal section of the gradually expanding section 31 is an isosceles trapezoid, and its diameter gradually increases outward from the end of the copper-steel composite connecting pipe 2. The welding point is located on the outer side of the gradually expanding section 31 near the connecting fitting 1, increasing the weld penetration.

[0057] Furthermore, the outer wall of the expanded diameter section 3 of the copper-steel composite connecting pipe 2 is not provided with a copper layer 22, which facilitates welding with other accessories.

[0058] Example 5

[0059] like Figure 8 As shown, in this embodiment, one end of the copper-steel composite connecting pipe 2 is provided with a reduced diameter section 4. The reduced diameter section 4 is inserted into the connecting fitting 1, and the inner wall of the connecting fitting 1 is attached to the outer wall of the reduced diameter section 4, making the connection convenient.

[0060] Furthermore, the outer wall area of ​​the reduced diameter section 4 that fits into the inner wall of the connecting fitting 1 is not provided with a copper layer 22.

[0061] Furthermore, the reduced-diameter section 4 includes a tapered section 41 and a second connecting section 42 arranged sequentially along the end edge of the copper-steel composite connecting pipe 2, with the second connecting section 42 inserted into the connecting fitting 1. The longitudinal section of the tapered section 41 is an isosceles trapezoid, and its diameter gradually decreases outward from the end of the copper-steel composite connecting pipe 2. The welding point is located on the outer side of the tapered section 41 near the connecting fitting 1, increasing the weld penetration.

[0062] Example 6

[0063] like Figure 9 As shown, in this embodiment, the end of the connecting fitting 1 away from the refrigeration system is provided with an expanded diameter section 3, and the end of the copper-steel composite connecting pipe 2 is provided with a reduced diameter section 4. The expanded diameter section 3 is sleeved on the reduced diameter section 4, and the inner wall of the expanded diameter section 3 is attached to the outer wall of the reduced diameter section 4, making the connection convenient.

[0064] Furthermore, the outer wall region of the reduced diameter section 4, which is attached to the inner wall of the expanded diameter section 3, is not provided with a copper layer 22.

[0065] Furthermore, the expanding section 3 includes a gradually expanding section 31 and a first connecting section 32 arranged sequentially along the end edge of the connecting fitting 1. The longitudinal section of the gradually expanding section 31 is an isosceles trapezoid, and its diameter gradually increases outward from the end of the connecting fitting 1. The reducing section 4 includes a gradually decreasing section 41 and a second connecting section 42 arranged sequentially along the end edge of the copper-steel composite connecting pipe 2. The longitudinal section of the gradually decreasing section 41 is an isosceles trapezoid, and its diameter gradually decreases outward from the end of the copper-steel composite connecting pipe 2. The first connecting section 32 is sleeved on the second connecting section 42, that is, the second connecting section 42 is inserted into the first connecting section 32. The welding point is located on the outer side of the gradually decreasing section 41 near the first connecting section 32, increasing the weld penetration.

[0066] Example 7

[0067] like Figure 10 As shown, in this embodiment, the end of the connecting fitting 1 away from the refrigeration system is provided with a reduced diameter section 4, and the end of the copper-steel composite connecting pipe 2 is provided with an expanded diameter section 3. The expanded diameter section 3 is sleeved on the reduced diameter section 4, and the inner wall of the expanded diameter section 3 is attached to the outer wall of the reduced diameter section 4, making the connection convenient.

[0068] Furthermore, the expanding section 3 includes a gradually expanding section 31 and a first connecting section 32 arranged sequentially along the end edge of the copper-steel composite connecting pipe 2. The longitudinal section of the gradually expanding section 31 is an isosceles trapezoid, and its diameter gradually increases outward from the end of the copper-steel composite connecting pipe 2. The reducing section 4 includes a gradually decreasing section 41 and a second connecting section 42 arranged sequentially along the end edge of the connecting fitting 1. The longitudinal section of the gradually decreasing section 41 is an isosceles trapezoid, and its diameter gradually decreases outward from the end of the connecting fitting 1. The first connecting section 32 is sleeved on the second connecting section 42, that is, the second connecting section 42 is inserted into the first connecting section 32. The welding point is located on the end of the first connecting section 32 near the end of the gradually decreasing section 41, increasing the weld penetration.

[0069] The above description is only a preferred embodiment of this utility model. For those skilled in the art, there will be changes in the specific implementation method and application scope based on the idea of ​​this utility model. The content of this specification should not be construed as a limitation of this utility model.

Claims

1. A refrigeration system connection tube structure, characterized by: It includes a connecting fitting (1) and a copper-steel composite connecting pipe (2). One end of the connecting fitting (1) is connected to the refrigeration system, and the other end of the connecting fitting (1) is abutted, sleeved or inserted into the copper-steel composite connecting pipe (2). The copper-steel composite connecting pipe (2) includes at least a steel layer (21) and a copper layer (22) arranged sequentially from the inside to the outside.

2. The refrigeration system connection tube structure according to claim 1, characterized by: The copper-steel composite connecting pipe (2) includes a copper layer, a steel layer (21) and a copper layer (22) arranged sequentially from the inside to the outside; the area where the connecting fitting (1) and the copper-steel composite connecting pipe (2) are in contact with each other does not have a copper layer (22).

3. The refrigerant system connection tube structure according to any one of claims 1 or 2, characterized by: The refrigeration system includes an air conditioning compressor and a liquid receiver. The connecting fitting (1) of the compressor abuts, sleeves, or inserts into the copper-steel composite connecting pipe (2). The connecting fitting (1) of the liquid receiver abuts, sleeves, or inserts into the copper-steel composite connecting pipe (2).

4. The refrigeration system connecting pipe structure according to claim 1, characterized in that: The connecting fitting (1) has a first sealing surface (11) at the end away from the refrigeration system, and the copper-steel composite connecting pipe (2) has a second sealing surface (23) at the end near the connecting fitting (1) that fits with the first sealing surface (11).

5. The refrigeration system connecting pipe structure according to claim 1, characterized in that: The connecting fitting (1) has an expansion section (3) or a reduction section (4) at the end away from the refrigeration system. The expansion section (3) is sleeved on the copper-steel composite connecting pipe (2), and the outer wall of the copper-steel composite connecting pipe (2) is attached to the inner wall of the expansion section (3). Alternatively, the reduction section (4) is inserted into the copper-steel composite connecting pipe (2), and the inner wall of the copper-steel composite connecting pipe (2) is attached to the outer wall of the reduction section (4).

6. The refrigeration system connecting pipe structure according to claim 1, characterized in that: One end of the copper-steel composite connecting pipe (2) is provided with an enlarged diameter section (3) or a reduced diameter section (4). The enlarged diameter section (3) is sleeved on the connecting fitting (1), and the outer wall of the connecting fitting (1) is attached to the inner wall of the enlarged diameter section (3). Alternatively, the reduced diameter section (4) is inserted into the connecting fitting (1), and the inner wall of the connecting fitting (1) is attached to the outer wall of the reduced diameter section (4).

7. The refrigeration system connecting pipe structure according to claim 1, characterized in that: The connecting fitting (1) has an expansion section (3) or a reduction section (4) at the end away from the refrigeration system. The copper-steel composite connecting pipe (2) has a reduction section (4) or an expansion section (3) at one end. The expansion section (3) is sleeved on the reduction section (4), and the inner wall of the expansion section (3) is attached to the outer wall of the reduction section (4).

8. The refrigeration system connecting pipe structure according to any one of claims 4-6, characterized in that: The expanding section (3) includes a gradually expanding section (31) and a first connecting section (32) arranged sequentially along the end edge of the copper-steel composite connecting pipe (2) or connecting fitting (1). The reducing section (4) includes a gradually reducing section (41) and a second connecting section (42) arranged sequentially along the end edge of the copper-steel composite connecting pipe (2) or connecting fitting (1). The first connecting section (32) is sleeved on the second connecting section (42), the connecting fitting (1) or the copper-steel composite connecting pipe (2), and the second connecting section (42) is inserted into the first connecting section (32), the connecting fitting (1) or the copper-steel composite connecting pipe (2).

9. The refrigeration system connecting pipe structure according to claim 2, characterized in that: The steel layer (21) is a stainless steel layer or a low-carbon steel layer, and the copper layer (22) is a copper layer.

10. The refrigeration system connecting pipe structure according to claim 1, characterized in that: The connecting fitting (1) and the copper-steel composite connecting pipe (2) are welded together by laser welding, carbon dioxide shielded welding, ion welding, high frequency welding or argon arc welding.

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