Large-pipe-diameter pipeline connecting structure, refrigeration accessory and refrigeration system

Abstract

The utility model provides a large-pipe-diameter pipeline connecting structure, a refrigeration accessory and a refrigeration system. The large-pipe-diameter pipeline connecting structure comprises a hollow main body piece, a stainless steel bearing plate, a stainless steel sleeve and a copper connecting pipe. The main body piece is made of stainless steel, and main body piece through holes communicating with the inner cavity are formed in the peripheral wall of the main body piece. The stainless steel bearing plate is welded to the peripheral wall of the main body piece in an attached mode, a bearing hole which is basically coaxial with the through hole of the main body piece is formed in the stainless steel bearing plate, and the hole diameter phi of the bearing hole is larger than or equal to 18 mm and smaller than or equal to 65 mm. And the front end of the stainless steel sleeve extends into the bearing hole to form assembly welding of the same metal. The copper connecting pipe is inserted into the stainless steel sleeve, a connecting pipe self-fluxing welding seam and / or a connecting pipe brazing layer are / is formed between the stainless steel sleeve and the copper connecting pipe, and the connecting pipe self-fluxing welding seam is a continuous circumferential welding seam formed by adopting self-fluxing welding or self-fluxing wire feeding welding or a plurality of local welding seams distributed at intervals.

Description

Technical Field

[0001] This utility model relates to the field of refrigeration system pipeline connection technology, and in particular to a large-diameter pipeline connection structure, refrigeration accessories, and refrigeration system. Background Technology

[0002] In refrigeration systems, to facilitate the collection or distribution of refrigerant, refrigeration components are typically connected vertically. This requires connecting holes to be drilled in the peripheral wall of the receiving body for inserting and welding the connecting pipes. To improve the connection strength after welding, the connecting holes are usually machined into flanges to increase the welding depth. However, due to limitations in material migration during flangering, the flange height is typically low (less than 2.5 mm). Furthermore, when the receiving body and the connecting pipe are connected as dissimilar metals (copper and steel), they are usually brazed in a furnace using tin bronze solder. Due to the characteristics of tin bronze solder, the resulting tin bronze brazed layer not only has a relatively loose metallographic structure, but the tin element also enhances the penetration cracks during copper-steel welding, thus affecting the connection strength of the tin bronze brazed layer. Obviously, when the pipe diameter is large (e.g., greater than 18 mm), the limited depth of the tin bronze brazed layer provided by the flanged holes will inevitably fail to meet the connection strength and pressure resistance requirements of the refrigeration system. Furthermore, due to the influence of the processing technology, the larger the pipe diameter, the more difficult it is to control the roundness of the flanged hole, and the worse the uniformity of the gap between the nozzle and the flanged hole will be. Tin bronze brazing filler metal penetrates into the gap during brazing based on capillary action, and it has high requirements for the assembly gap (generally required to be between -0.05mm and 0.1mm). Therefore, when the nozzle diameter is large, part of the gap between the nozzle and the flanged hole may exceed the capillary penetration gap requirement of tin bronze, resulting in weld breakage, which further deteriorates the connection strength of large-diameter nozzles when brazed with tin bronze.

[0003] To address this, the inventors proposed adding multiple backing plates to the perimeter of the receiving body, using the overlapping of holes in these plates to increase the welding depth of the copper connector. However, due to limitations in the punching process, the backing plates are relatively thin, requiring a large number of backing plates to meet the welding depth requirements of large-diameter connectors. This results in a long solder flow path and a large filling area, while tin bronze brazing solder has poor fluidity, leading to welding problems such as incomplete or broken welds between adjacent backing plates after welding.

[0004] Furthermore, the inventors proposed a pipe connection structure with an outer liner in Chinese patent CN221004242U. The sheet-like base of the outer liner is fitted to the outer wall of the main pipe, and the connecting hole on the outer liner coaxially connects to the branch pipe hole on the main pipe. The connecting hole and the branch pipe hole together provide welding depth for the branch pipe. In this structure, the height of the connecting hole on the outer liner is not limited by the material and shape of the main pipe, so its height can be matched and processed according to the required welding strength of the branch pipe, thereby effectively improving the problem of insufficient welding depth at the pipe hole when refrigeration accessories are vertically connected. In Chinese patent CN221004242U, the sheet-like base on the outer liner has a curved structure, while the connecting part is a straight section with a weldable straight body. This irregular structure makes the outer liner extremely difficult to process, and it is mainly formed by casting or machining. Casting not only has high processing costs and low efficiency, but the casting also suffers from poor connection strength due to large grain size and defects such as a certain amount of porosity and inclusions in the microstructure. Machining, on the other hand, presents challenges due to the difficulty in machining tools, high costs, low efficiency, and difficulty in ensuring the uniformity of curvature of the machined sheet-like base. When the sheet-like base is attached to the outer wall of the main pipe, the uniformity of the fit between the two is poor, making it easy for welding quality problems such as incomplete welds and broken welds to occur during brazing. Utility Model Content

[0005] In order to overcome the shortcomings of the prior art, this utility model provides a large-diameter pipe connection structure, refrigeration accessories, and refrigeration system with excellent welding strength.

[0006] To achieve the above objectives, this utility model provides a large-diameter pipe connection structure, comprising a hollow main body, a stainless steel receiving plate, a stainless steel sleeve, and a copper connecting pipe. The main body is made of stainless steel and has a through hole on its peripheral wall communicating with the inner cavity. The stainless steel receiving plate is welded to the outer peripheral wall of the main body, and a receiving hole is formed on the stainless steel receiving plate that is substantially coaxial with the through hole of the main body, with a hole diameter Φ greater than or equal to 18mm and less than or equal to 65mm. The front end of the stainless steel sleeve extends into the receiving hole to form a homogeneous metal assembly weld. The copper connecting pipe is inserted into the stainless steel sleeve, and a self-fusion weld and / or a brazed layer are formed between the stainless steel sleeve and the copper connecting pipe. The self-fusion weld is a continuous circumferential weld or multiple spaced local welds formed by self-fusion welding or self-fusion wire feeding welding.

[0007] According to one embodiment of the present invention, the self-fusion weld of the connector is an arc weld formed by arc welding, and the arc weld is formed between at least one end of the stainless steel sleeve and the copper connector.

[0008] According to one embodiment of the present invention, the assembly length L1 of the stainless steel sleeve and the copper connector is greater than or equal to the larger of 0.05Φ and 2.5mm, where Φ is the diameter of the receiving hole, and a brazed layer of the connector is formed in the assembly gap between the two.

[0009] According to one embodiment of the present invention, in the overlapping area of ​​the stainless steel sleeve and the copper pipe, an exhaust hole for discharging gas is formed on the pipe wall of the copper pipe and / or the pipe wall of the stainless steel sleeve.

[0010] According to one embodiment of the present invention

[0011] The stainless steel sleeve is connected to the receiving hole and / or the main component via a brazed layer.

[0012] When a brazed layer is formed in the assembly gap between the stainless steel sleeve and the copper connector, the brazed layer of the steel sleeve and the brazed layer of the connector are alloy layers formed by the same type of brazing filler; or, the brazed layer of the connector is an alloy layer formed by brazing filler with a liquidus line lower than that of the steel sleeve.

[0013] According to one embodiment of the present invention, a steel sleeve reinforcing weld is formed between the outer peripheral wall of the stainless steel sleeve and the stainless steel receiving plate to reinforce the stainless steel sleeve. The steel sleeve reinforcing weld is a continuous circumferential weld or multiple spaced local welds formed by self-fusion welding or wire feeding welding.

[0014] According to one embodiment of the present invention, the stainless steel sleeve is connected to the receiving hole via a self-fusion circumferential weld or a self-fusion wire-feeding circumferential weld.

[0015] According to one embodiment of the present invention, the front end of the stainless steel sleeve extends through the receiving hole to abut against the outer peripheral wall of the main body near the through hole of the main body or is inserted into the through hole of the main body.

[0016] According to one embodiment of the present invention, the diameter of the receiving hole is larger than the diameter of the through hole of the main body, and the difference between the two diameters is basically close to or greater than the wall thickness of the front end of the stainless steel sleeve. The end face of the front end of the stainless steel sleeve extends through the receiving hole to abut against the outer peripheral wall of the main body.

[0017] According to one embodiment of the present invention, the main body is a pipe or container with a cross-section close to a circle, and the end face of the front end of the stainless steel sleeve is curved to fit and weld to the outer peripheral wall of the main body.

[0018] According to one embodiment of the present invention, the diameter of the receiving hole is basically close to the diameter of the through hole of the main body, the front end of the stainless steel sleeve extends into the through hole of the main body through the receiving hole, and the front end of the stainless steel sleeve is also welded to the through hole of the main body.

[0019] According to one embodiment of the present invention, the end face of the front end of the stainless steel sleeve is substantially flush with the inner peripheral wall of the main body; or, the end face of the front end of the stainless steel sleeve extends into the inner cavity of the main body through the through hole of the main body.

[0020] According to one embodiment of the present invention, a reinforcing weld is formed between the edge of the stainless steel receiving plate and the outer peripheral wall of the main body. The reinforcing weld is a continuous circumferential weld or multiple spaced local welds formed by self-fusion welding or wire feeding welding.

[0021] On the other hand, this utility model also provides a large-diameter pipe connection structure, which includes a hollow main body, a stainless steel sleeve, and a copper connector. The main body is made of stainless steel and has a through hole on its peripheral wall that communicates with the inner cavity. A flange is formed on the through hole of the main body, and the diameter Φ of the flange is greater than or equal to 18 mm and less than or equal to 65 mm. The front end of the stainless steel sleeve and the flange are assembled with the same metal, and the assembly is connected by a self-fusion circumferential weld or a self-fusion wire-feed circumferential weld. The copper connector is inserted into the stainless steel sleeve, and a self-fusion weld and / or a brazed layer are formed between the stainless steel sleeve and the copper connector. The self-fusion weld is a continuous circumferential weld or multiple spaced local welds formed by self-fusion welding or self-fusion wire-feed welding.

[0022] On the other hand, this utility model also provides a large-diameter pipe connection structure, which includes a hollow main body, a stainless steel sleeve, and a copper connector. The main body is a stainless steel pipe with an inner diameter greater than or equal to 18 mm. The front end of the stainless steel sleeve and the axial end of the main body form a homogeneous metal assembly, and the assembly is connected by a self-fusion circumferential weld or a self-fusion wire-feed circumferential weld. The copper connector is inserted into the stainless steel sleeve, and a self-fusion weld and / or a brazed layer are formed between the stainless steel sleeve and the copper connector. The self-fusion weld is a continuous circumferential weld or multiple spaced local welds formed by self-fusion welding or self-fusion wire-feed welding.

[0023] On the other hand, this utility model also provides a large-diameter pipe connection structure, which includes a hollow main body, a receiving plate, a copper connecting sleeve, and a copper connecting pipe. The hollow main body is made of stainless steel and has a through hole on its peripheral wall that communicates with the inner cavity. The receiving plate is welded to the outer peripheral wall of the main body, and a receiving hole is formed on the receiving plate that is substantially coaxial with the through hole of the main body, and the diameter of the receiving hole Φ is greater than or equal to 18mm and less than or equal to 65mm. The front end of the copper connecting sleeve is brazed to the receiving hole. The copper connecting pipe is sleeved on the copper connecting sleeve, and a self-fusion weld and / or a brazed layer formed by non-furnace brazing are formed between the copper connecting sleeve and the copper connecting pipe. The self-fusion weld is a continuous circumferential weld or multiple spaced local welds formed by self-fusion welding or self-fusion wire feeding welding.

[0024] On the other hand, this utility model also provides a refrigeration accessory, which includes the above-mentioned large-diameter pipe connection structure.

[0025] On the other hand, this utility model also provides a refrigeration system, which includes the above-mentioned refrigeration accessories; or, includes the above-mentioned large-diameter pipe connection structure.

[0026] In summary, the large-diameter pipe connection structure provided by this utility model, by adding a stainless steel receiving plate and a stainless steel sleeve, transforms the welding at the through-hole of the main component with limited assembly depth from traditional dissimilar metal welding of copper and steel to homogeneous metal welding of stainless steel, greatly reducing welding difficulty and effectively improving welding strength. Furthermore, the separate stainless steel receiving plate and stainless steel sleeve allow for independent processing. The stainless steel receiving plate can be formed through a simple stamping process, resulting in high forming efficiency and ensuring that its curvature matches the outer perimeter of the main component well, thus creating a uniform gap between the two that meets brazing requirements.

[0027] Furthermore, the use of stainless steel or copper connecting sleeves allows for independent assembly and welding of the copper pipe. Large main components do not need to be welded to the copper pipe, resulting in high welding efficiency, flexibility, and low cost. Simultaneously, the copper pipe remains unaffected by the welding of the main component, maintaining excellent strength and ductility. Moreover, the stainless steel or copper connecting sleeves remove the limitation of the copper pipe's assembly depth from the through-hole of the main component. For copper pipes of different diameters, simply adjusting the length of the stainless steel sleeve allows the assembly depth to meet the refrigeration system requirements, thus providing excellent versatility.

[0028] To make the above and other objects, features and advantages of this utility model more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0029] Figure 1 The diagram shown is a schematic diagram of the large-diameter pipeline connection structure provided in Embodiment 1 of this utility model.

[0030] Figure 2 As shown Figure 1 A partial cross-sectional schematic diagram.

[0031] Figure 2A As shown Figure 1 Enlarged diagram of point A in the middle.

[0032] Figure 3 As shown Figure 1 A schematic diagram of the structure of the central pipe assembly assembled on the main body assembly.

[0033] Figure 4 and Figure 5 The diagram shown is a schematic diagram of a large-diameter pipeline connection structure provided in another embodiment of this utility model.

[0034] Figure 6 and Figure 7 The diagram shown is an assembly schematic of the stainless steel sleeve and copper connector in a large-diameter pipe connection structure provided in another embodiment of this utility model.

[0035] Figure 8 The diagram shown is a schematic diagram of the large-diameter pipe connection structure provided in Embodiment 1 of this utility model, with an exhaust hole provided on the connecting pipe.

[0036] Figure 9 As shown Figure 8 A schematic diagram of the structure of the copper pipe.

[0037] Figure 10 The diagram shown is a structural schematic of the copper connector in another embodiment of this utility model.

[0038] Figure 11 The diagram shown is a schematic diagram of a large-diameter pipeline connection structure provided in another embodiment of this utility model.

[0039] Figure 12 As shown Figure 11 Enlarged diagram of point B in the middle.

[0040] Figure 13 The diagram shown is a structural schematic of the refrigeration accessory provided in Embodiment 1 of this utility model.

[0041] Figure 13A This is a schematic diagram of a large-diameter pipeline connection structure provided in another embodiment of the present invention.

[0042] Figure 14 The diagram shown is a schematic diagram of the large-diameter pipeline connection structure provided in Embodiment 2 of this utility model.

[0043] Figure 15 As shown Figure 14 Enlarged diagram of point C in the middle.

[0044] Figure 16 and Figure 17 The diagram shown is a partial schematic of a large-diameter pipe connection structure provided in another embodiment of this utility model.

[0045] Figure 18 The diagram shown is a schematic diagram of the large-diameter pipe connection structure provided in Embodiment 3 of this utility model.

[0046] Figure 19 As shown Figure 18 A structural diagram from another perspective.

[0047] Figure 20 As shown Figure 18 A cross-sectional view along the DD line.

[0048] Figure 21 As shown Figure 20 Enlarged diagram of point E in the middle.

[0049] Figure 22The diagram shown is a partial schematic of the large-diameter pipe connection structure provided in Embodiment 4 of this utility model.

[0050] Figure 23 As shown Figure 22 A partial cross-sectional schematic diagram.

[0051] Figure 24 The diagram shown is a partial schematic of the large-diameter pipe connection structure provided in Embodiment 5 of this utility model. Detailed Implementation

[0052] In vertical connection structures of refrigeration pipe fittings, the assembly depth at the nozzle holes on the peripheral wall of the receiving body is limited due to factors such as the wall thickness and material migration. When copper-steel dissimilar metal welding is performed at this location, only a tin bronze brazing layer with limited welding depth can be formed. The wettability of tin bronze brazing material at the copper-steel interface and its high requirements for assembly clearance during capillary penetration determine that when welding large-diameter pipe fittings, not only is the brazing layer short and the metallographic structure loose, but it is also prone to welding defects such as weld breakage, severely affecting the connection strength of vertical connections of large-diameter pipes. While adding an external bushing can solve the problem of insufficient welding depth for copper-steel dissimilar metals, it still cannot solve the problems of low connection strength, poor airtightness, and easy welding defects when welding large-diameter pipe fittings caused by the loose metallographic structure of the tin bronze brazing layer. Furthermore, the irregular structure of the external bushing also greatly limits the mass production of this solution.

[0053] In view of this, this embodiment provides a large-diameter pipe connection structure 100 with excellent welding strength. For example... Figure 1 , Figure 2 as well as Figure 2A As shown, the large-diameter pipe connection structure 100 provided in this embodiment includes a hollow main body 1, a stainless steel receiving plate 2, a stainless steel sleeve 3, and a copper connecting pipe 4. The main body 1 is made of stainless steel and has a through hole 11 on its peripheral wall that communicates with the inner cavity. The stainless steel receiving plate 2 is welded to the outer peripheral wall of the main body 1. A receiving hole 21 is formed on the stainless steel receiving plate 2, which is substantially coaxial with the through hole 11 of the main body. The diameter Φ of the receiving hole 21 is greater than or equal to 18 mm and less than or equal to 65 mm. The front end 31 of the stainless steel sleeve extends into the receiving hole 21 to form a homogeneous metal assembly weld. The copper connecting pipe 4 is inserted into the stainless steel sleeve 3. A self-fusion weld 10 and / or a brazed layer 40 are formed between the stainless steel sleeve 3 and the copper connecting pipe 4. The self-fusion weld 10 is a continuous circumferential weld or multiple spaced local welds formed by self-fusion welding or self-fusion wire feeding welding.

[0054] In this embodiment, the large-diameter pipe connection structure is a manifold structure for collecting or distributing refrigerant. However, the present invention does not limit this in any way. In other embodiments, the large-diameter pipe connection structure may also be other connection structures involving vertical pipe connections, such as a T-junction structure.

[0055] In the large-diameter pipeline connection structure provided in this embodiment, the stainless steel receiving plate 2 and stainless steel sleeve 3 enable the formation of a stainless steel homometallic weld at the through hole 11 of the main component, where the assembly depth is limited. Compared with copper-steel dissimilar metal welding, stainless steel homometallic welding is not only easier to weld, but also significantly reduces the assembly depth requirements due to the high-strength, corrosion-resistant weld (or brazed layer) formed after welding. Furthermore, the separate design of the stainless steel receiving plate 2 and stainless steel sleeve 3 allows for independent processing. The stainless steel receiving plate 2 can be formed by simple stamping and bending, and its shape can well match the outer peripheral wall of the main component 1, thus creating a uniform assembly gap that meets the brazing requirements. Moreover, the stainless steel sleeve 3 also allows the dissimilar metal welding on the large-diameter pipeline connection structure to be transferred from the through hole of the main component, where the brazing depth is limited and the brazing gap is difficult to control, to the axial end of the stainless steel sleeve 3, providing conditions for brazing and / or self-fusion welding at this location.

[0056] In this embodiment, the front end 31 of the stainless steel sleeve is welded to the receiving hole 21 via a self-fusion circumferential weld 20. This weld is formed by the partial melting and mutual dissolution of the stainless steel receiving plate 2 and the stainless steel sleeve 3 at the receiving hole 21, resulting in a liquid weld. Upon solidification, the liquid weld crystallizes and grows from the fusion zone through homogeneous or heterogeneous epitaxy, connecting to the unmelted base materials (stainless steel receiving plate 2 and stainless steel sleeve 3) on both sides via metallic bonds. Compared to brazing layers formed by metallurgical diffusion dissolution (especially brazing layers of tin bronze with a relatively loose metallographic structure), the self-fusion circumferential weld 20, which is of the same composition as the base material and connected by metallic bonds, is far superior to traditional brazing layers in both connection strength and corrosion resistance. Specifically, arc welding (such as argon arc welding) can be used to form the self-fusion circumferential weld 20. However, this invention does not impose any limitations on this. In other embodiments, wire feeding can be performed on the basis of autofusion welding, and other metal elements can be added to form an autofusion wire-feed weld with better weld performance.

[0057] Specifically, such as Figure 3As shown, during welding, the stainless steel receiving plate 2 and the main body 1 can be brazed first to form the main assembly, while the stainless steel sleeve 3 is first connected to the copper pipe 4 through the pipe self-fusion weld 10 and / or the pipe brazed layer 40 to form the pipe assembly. Then, the stainless steel sleeve 3 inside the pipe assembly is assembled into the receiving hole 21 on the main assembly, and the two are connected at the assembly point using a self-fusion circumferential weld 20. This assembly method allows the main assembly and pipe assembly to be processed independently, and large-sized main assemblies do not need to be welded along with the pipe assembly (especially during the long tunnel furnace brazing process when forming the pipe brazed layer 40), thus greatly improving welding efficiency. Furthermore, this setup allows the welding of the pipe assembly to be unrestricted by the main assembly; smaller pipe assemblies are very flexible whether self-fusion welding or brazing is used. Specifically, when the pipe assembly is brazed, it can be placed vertically on the tunnel furnace conveyor belt to better facilitate the penetration of the brazing filler metal. Furthermore, this setup also allows large-sized main assemblies to be matched with pipe assemblies of different specifications, providing excellent versatility.

[0058] In this embodiment, the high-strength, corrosion-resistant self-fluxing circumferential weld 20 significantly reduces the assembly depth requirement of the stainless steel sleeve 3 at the receiving hole 21. Only one or two stainless steel receiving plates 2 need to be installed on the outer peripheral wall of the main component 1 to ensure that the connection strength of the stainless steel sleeve 3 meets the requirements of the refrigeration system. Specifically, as shown in the example... Figure 1 As shown, the main component 1 is a pipe with a nearly circular cross-section (i.e., a circular pipe). The stainless steel receiving plate 2 is a single, curved piece designed to be welded to the outer periphery of the main component 1. At this point, there is only a small assembly gap between the stainless steel receiving plate 2 and the outer periphery of the main component 1, resulting in a short brazing path. The brazing material can quickly penetrate the assembly gap to form a uniform and full brazing layer. Preferably, oxygen-free copper brazing material with excellent welding fluidity and suitability for brazing stainless steel can be used for welding. The brazing layer formed by this brazing material is not only corrosion-resistant but also has high connection strength. However, this invention does not limit this aspect. The large contact area between the stainless steel receiving plate 2 and the main component 1 also allows for the use of other brazing materials, such as tin bronze brazing material. Furthermore, this invention does not limit the number of stainless steel receiving plates 2. In other embodiments, the high fluidity of the brazing material also allows for the use of two or more stainless steel receiving plates.

[0059] In this embodiment, as Figure 2 and Figure 2A As shown, a reinforcing weld 30 is further provided between the edge of the stainless steel receiving plate 3 and the outer peripheral wall of the main body 1 to further improve the connection strength between the two. Specifically, the reinforcing weld 30 is a continuous circumferential weld formed by self-fusion welding (such as argon arc welding or laser welding) or wire feeding welding. However, this utility model does not limit this in any way. In other embodiments, the reinforcing weld 30 may also be multiple spaced local welds.

[0060] In this embodiment, as Figure 2A and Figure 3 As shown, the diameter of the receiving hole 21 is larger than the diameter of the through hole 11 of the main body, and the difference in diameter ΔΦ between the two is approximately close to or greater than the wall thickness of the front end 31 of the stainless steel sleeve. The end face of the front end 31 of the stainless steel sleeve extends through the receiving hole 21 to abut against the outer peripheral wall of the main body 1 near the through hole 11 of the main body. The outer peripheral wall of the stainless steel sleeve 3 is connected to the receiving hole 21 via a self-fusion circumferential weld 20. This arrangement allows the receiving hole 21 to not only provide the assembly depth for the stainless steel sleeve 3 during insertion and assembly, but also to limit its circumferential position to ensure that the axis of the stainless steel sleeve 3 is substantially coincident with the axis of the through hole 11 of the main body after assembly, thus achieving coaxiality positioning. At the same time, this arrangement can also use the outer peripheral wall of the main body 1 to axially limit the insertion depth of the stainless steel sleeve 3, eliminating the need for additional assembly limiting parts and simplifying the assembly process. Furthermore, to improve the assembly stability and connection strength of the stainless steel sleeve 3, the end face of the front end 31 of the stainless steel sleeve is curved to fit against the outer peripheral wall of the main body 1. Specifically, the end face of the stainless steel sleeve front end 31 can be curved using laser cutting. However, this invention does not impose any limitations on this. In other embodiments, the end face of the stainless steel sleeve front end can also be set to be flat to partially abut against the outer peripheral wall of the main body.

[0061] Although this embodiment is described using the example of the stainless steel sleeve front end 31 abutting against the outer peripheral wall of the main body 1, this utility model does not impose any limitations on it. In other embodiments, such as Figure 4 As shown, the diameter of the receiving hole 21 can also be set to be approximately close to the diameter of the through hole 11 of the main body. The front end 31 of the stainless steel sleeve extends into the through hole 11 of the main body through the receiving hole 21. The receiving hole 21 and the through hole 11 of the main body together provide the assembly depth and coaxiality positioning for the stainless steel sleeve 3. The outer peripheral wall of the stainless steel sleeve 3 is connected to the receiving hole 21 through a self-fusion circumferential weld 20. Figure 4 In this embodiment, the end face of the front end 31 of the stainless steel sleeve is substantially flush with the inner peripheral wall of the main body 1. However, this utility model does not impose any limitation on this. In other embodiments, the end face of the front end 31 of the stainless steel sleeve may also be arranged to extend into the inner cavity of the main body 1 through the through hole 11 of the main body (e.g., Figure 5 (As shown). This arrangement can increase the assembly length of the connection between the stainless steel sleeve 3 and the copper connector 4 when the exposed length of the stainless steel sleeve 3 (the length exposed beyond the main body 1) is limited.

[0062] In the large-diameter pipe connection structure provided in this embodiment, the stainless steel receiving plate 2 and the stainless steel sleeve 3 transfer the copper-steel dissimilar metal welding joint from the through hole 11 of the main component, which has a limited welding depth and is vertically connected, to the axial connection of the stainless steel sleeve 3. The stainless steel sleeve 3 and the copper connecting pipe 4 are connected by a combination of fusion welding and brazing to form a high-strength self-fusion weld 10 and a brazed layer 40, ensuring that the copper-steel dissimilar metal welding meets the requirements of the refrigeration system in terms of connection strength, airtightness, and corrosion resistance.

[0063] like Figure 2 and Figure 2A As shown, the self-fusion weld 10 of the connector is an arc weld formed by arc welding, and the arc weld is formed between the end 32 of the stainless steel sleeve and the copper connector 4. However, this utility model does not limit this in any way. In other embodiments, the self-fusion weld 10 of the connector may also be formed between the front end 31 of the stainless steel sleeve and the copper connector 4, such as... Figure 6 As shown. Alternatively, the connector is formed at both ends of the stainless steel sleeve by the self-fusion weld 10, as shown. Figure 7 As shown. In this embodiment, as Figure 2A As shown, the assembly length L1 of the stainless steel sleeve 3 and the copper connector 4 is greater than or equal to the larger of 0.05Φ and 2.5mm, where Φ is the diameter of the receiving hole 21. A brazed layer 40 is formed within the assembly gap between the two, and this brazed layer 40 is a tin bronze brazed layer. However, this invention does not limit this. In other embodiments, it can also be an alloy layer formed after welding with a brazing filler metal with a liquidus temperature below 920°C (such as copper-silver-phosphorus brazing filler metal). Specifically, in this embodiment, the self-fusion weld 10 of the connector is a continuous circumferential weld. The continuous circumferential weld located at the end 32 of the stainless steel sleeve not only greatly improves the connection strength and pressure resistance of the copper connector 4, but also isolates the brazed layer 40 from the outside environment, preventing the brazed layer 40 from being corroded by the external environment and greatly improving the corrosion resistance of the connector after welding. However, this invention does not limit this. The axial sleeve assembly method between the stainless steel sleeve 3 and the copper connector 4 allows for free adjustment of the assembly length between them; during brazing assembly, the brazing area can also be increased by adjusting the sleeve assembly length, thereby improving the connection strength of the brazed layer 40 of the connector. The improved performance of the brazed layer 40 of the connector allows the self-fusion weld 10 of the connector in other embodiments to be multiple spaced local welds.

[0064] In the large-diameter pipe connection structure provided in this embodiment, the self-fusion weld 10 and the brazed layer 40 of the connector provide dual protection in terms of connection strength and sealing. Simultaneously, the self-fusion weld 10 also isolates and protects the brazed layer 40, significantly improving the connection strength, pressure resistance, and corrosion resistance after welding dissimilar metals like copper and steel. However, this utility model does not impose any limitations on this. In other embodiments, only a brazed layer may be provided between the stainless steel sleeve and the copper connector; in this case, the brazing area can be increased by adjusting the fitting length between the stainless steel sleeve and the copper connector, thereby improving the connection strength of the brazed layer. Furthermore, in other embodiments, when the self-fusion weld is a continuous circumferential weld and its connection strength is sufficient to meet the requirements of the refrigeration system, a brazed layer may not be necessary between the stainless steel sleeve and the copper connector.

[0065] Furthermore, to increase the penetration path of the brazing layer 40 in the connector, vent holes 41 are formed on the wall of the copper connector 4 within the socket area, communicating with its inner cavity. During brazing, the gas in the assembly gap between the stainless steel sleeve 3 and the copper connector 4 is discharged into the inner cavity of the copper connector 4 through the vent holes 41, reducing the resistance in the assembly gap and thus increasing the penetration path of the brazing filler metal. Specifically, as shown... Figure 8 and Figure 9 As shown, the copper connector 4 within the socket area has two rows of vent holes distributed axially along its wall, each row containing multiple vent holes 41 evenly distributed circumferentially along the copper connector 4. However, this invention does not limit this to any particular embodiment. In other embodiments, a single row of vent holes may also be provided on the copper connector, such as... Figure 10 As shown. Furthermore, in other embodiments, vent holes can be formed on the stainless steel sleeve wall within the socket area; in this case, it is preferable to set the self-fusion weld of the connector on the circumferential wall of the stainless steel sleeve near the insertion end of the copper connector.

[0066] In this embodiment, the main body 1 is a tube with a nearly circular cross-section. However, this invention does not impose any limitations on this. In other embodiments, the main body 1 may also be a tank or container with a nearly circular cross-section, such as... Figure 11 As shown. Figure 12 for Figure 11 The enlarged diagram at point B in the middle, and Figure 2 and Figure 2A Basically the same, the stainless steel sleeve 3 is connected to the receiving hole on the stainless steel receiving plate 2 via a self-fusion circumferential weld 20, and a self-fusion weld 10 and a brazing layer 40 are formed between the stainless steel sleeve 3 and the copper connecting pipe 4.

[0067] Corresponding to the aforementioned large-diameter pipe connection structure, this embodiment also provides a refrigeration accessory. For example... Figure 13As shown, this refrigeration accessory is a central air conditioning module unit's manifold assembly, which includes the aforementioned large-diameter pipe connection structure 100 and multiple copper manifolds 200. Each manifold 200 is welded to a corresponding copper connector 4 within the large-diameter pipe connection structure 100, and multiple branch pipes 201 are formed on the manifold 200. However, this utility model does not limit this in any way. In other embodiments, the manifold 200 can also be the large-diameter pipe connection structure provided in this embodiment, such as... Figure 13A As shown.

[0068] In other embodiments, the refrigeration fitting may also be a tank assembly or other fittings involving vertical pipe connections.

[0069] Correspondingly, this embodiment also provides a refrigeration system including the aforementioned large-diameter pipe connection structure and / or refrigeration accessories. Specifically, the refrigeration system can be a central air conditioning module unit, a central air conditioning water system, a low-temperature heat pump system using carbon dioxide refrigerant, or a cold storage system.

[0070] Example 2

[0071] This embodiment is basically the same as Embodiment 1 and its variations, except that: the stainless steel sleeve 3 is welded to the receiving hole 21 and the outer peripheral wall of the main body 1 via the steel sleeve brazing layer 50.

[0072] like Figure 14 and Figure 15 As shown, in this embodiment, the main body 1, the stainless steel receiving plate 2, and the stainless steel sleeve 3 are integrally welded together by furnace brazing. The outer peripheral wall of the front end 31 of the stainless steel sleeve is connected to the receiving hole via the brazed layer 50 of the steel sleeve. Figure 15 The stainless steel sleeve 3 is assembled at its front end 31 (so it is not labeled), and the end face of the front end 31 is connected to the outer peripheral wall of the main body 1 via a brazed layer 50. Furthermore, a reinforcing weld 60 is formed between the outer peripheral wall of the stainless steel sleeve 3 and the stainless steel receiving plate 2 to strengthen the stainless steel sleeve 3. The reinforcing weld 60 is a continuous circumferential weld or multiple spaced local welds formed by self-fusion welding or wire feeding welding. The reinforcing weld 60 not only enhances the connection strength of the stainless steel sleeve 3 based on the brazed layer 50, but also protects the brazed layer 50 from external harmful substances, thereby improving the corrosion resistance of the stainless steel sleeve 3 connection.

[0073] In the specific welding process, the outer peripheral wall of the stainless steel sleeve 3 and the stainless steel receiving plate 2 can first be welded using argon arc welding to form a steel sleeve reinforcing weld 60; then, the main body 1, the stainless steel receiving plate 2, and the stainless steel sleeve 3 are integrally brazed in the furnace; finally, the copper connecting pipe 4 is assembled onto the stainless steel sleeve 3, and the two are then welded together using arc welding or arc wire feeding welding to form a self-fusion weld 10 for the connecting pipe. However, this utility model does not limit the welding method for forming the steel sleeve reinforcing weld. In other embodiments, self-fusion welding (such as resistance welding) or self-fusion wire feeding welding can also be used to form the steel sleeve reinforcing weld.

[0074] In this embodiment, the main body 1, the stainless steel receiving plate 2, and the stainless steel sleeve 3 are integrally brazed in an oxygen-free copper furnace, and the brazing layer 50 of the steel sleeve is a high-strength, corrosion-resistant oxygen-free copper brazing layer. However, this utility model does not limit this in any way. In other embodiments, the main body 1, the stainless steel receiving plate 2, and the stainless steel sleeve 3 can also be brazed in a furnace using tin bronze brazing filler. In this case, although the brazing layer 50 of the steel sleeve is a tin bronze brazing layer with relatively weak connection strength and density, the high-strength, high-density steel sleeve reinforcing weld 60 can compensate for the deficiencies of the tin bronze brazing layer, thereby ensuring that the connection strength and airtightness of the stainless steel sleeve 3 can meet the requirements of the refrigeration system.

[0075] In the large-diameter pipe connection structure provided in this embodiment, if a brazing layer 40 is formed between the stainless steel sleeve 3 and the copper connecting pipe 4, since the brazing layer 40 is formed after the brazing layer 50 of the steel sleeve, the liquidus of the brazing material corresponding to the brazing layer 40 is required to be lower than that of the brazing layer 50 of the steel sleeve to avoid secondary welding of the brazing layer 50 of the steel sleeve. However, this utility model does not impose any limitation on this. In other embodiments, the brazing layer of the connecting pipe and the brazing layer of the steel sleeve can also be an alloy layer formed by the same type of brazing material, such as tin bronze brazing layers. In the specific welding process, the stainless steel sleeve and the copper connecting pipe are first subjected to self-fusion welding or self-fusion wire feeding welding to form a connecting pipe assembly; then the stainless steel receiving plate and the connecting pipe assembly are assembled onto the main body and pre-fixed; finally, the main body, the stainless steel receiving plate, and the connecting pipe assembly are brazed in an integrated manner in a tin bronze furnace. Although this embodiment is described with the end face of the front end 31 of the stainless steel sleeve abutting against the outer peripheral wall of the main body 1 as an example. However, this invention does not limit itself in any way. In other embodiments, such as Figure 16 As shown, a receiving hole (not marked because it is assembled with the front end 31 of the stainless steel sleeve) can also be provided, with a diameter approximately close to that of the through hole 11 in the main body. The outer peripheral wall of the front end 31 of the stainless steel sleeve is connected to the receiving hole and the through hole 11 in the main body via the brazing layer 50 of the steel sleeve. Further, as... Figure 17As shown, an inner stainless steel receiving plate 2 can be added to the inner peripheral wall of the main body 1. The front end 31 of the stainless steel sleeve is connected to the receiving hole on the outer stainless steel receiving plate 2, the through hole of the main body and the receiving hole on the inner stainless steel receiving plate 2 through the brazing layer 50 of the steel sleeve, so as to further improve the connection strength of the stainless steel sleeve 3.

[0076] The connection method between the stainless steel sleeve 3 and the copper pipe 4 is basically the same as that in Embodiment 1, and will not be described in detail here.

[0077] Example 3

[0078] This embodiment is basically the same as Embodiment 1 and its variations, except that: no stainless steel support plate is provided on the outer peripheral wall of the main body 1.

[0079] like Figures 18 to 21 As shown, the large-diameter pipe connection structure provided in this embodiment includes a hollow main body 1, a stainless steel sleeve 3, and a copper connector 4. The main body 1 is made of stainless steel and has a through hole 11 on its peripheral wall that communicates with the inner cavity. A flange 111 is formed on the through hole 11, and the diameter Φ of the flange 111 is greater than or equal to 18 mm and less than or equal to 65 mm. The front end 31 of the stainless steel sleeve and the flange 111 are assembled with the same metal, and the assembly is connected by a self-fusion circumferential weld 20 or a self-fusion wire-feed circumferential weld. The copper connector 4 is inserted into the stainless steel sleeve 3. A self-fusion weld 10 and / or a brazed layer 40 are formed between the stainless steel sleeve 3 and the copper connector 4. The self-fusion weld 10 is a continuous circumferential weld or multiple spaced local welds formed by self-fusion welding or self-fusion wire-feed welding.

[0080] Similar to Embodiment 1, a high-strength, corrosion-resistant self-fluxing circumferential weld 20 is formed by welding the stainless steel sleeve 3 and the stainless steel flange 111 together with the same metal. This weld significantly reduces the impact of the assembly depth at the flange 111 on the connection strength. At this point, although the flange 111 is relatively short, the self-fluxing circumferential weld 20 formed between it and the stainless steel sleeve 3 can well meet the requirements of the refrigeration system in terms of connection strength and sealing performance. Specifically, the front end 31 of the stainless steel sleeve is inserted into the flange 111, and the self-fluxing circumferential weld 20 is formed between the outer peripheral wall of the stainless steel sleeve 3 and the flange 111 by argon arc welding. However, this invention does not impose any limitations on this. In other embodiments, laser welding can also be used to form the self-fluxing circumferential weld. Furthermore, wire feeding can be performed on the basis of argon arc welding or laser welding, and other metal elements can be added to form a self-fluxing wire-feeding circumferential weld with even better performance.

[0081] Although this embodiment is described using the assembly method of the stainless steel sleeve 3 being inserted into the flange 111 as an example, the present invention does not impose any limitations on this. In other embodiments, the stainless steel sleeve may also be butt-welded to the flange and then subjected to a self-fusion circumferential weld.

[0082] Similarly, the connection method between the stainless steel sleeve 3 and the copper pipe 4 is basically the same as that in Embodiment 1, and will not be described again here.

[0083] Example 4

[0084] As described in Embodiment 1, the stainless steel receiving plate 2 and the stainless steel sleeve 3 are welded via the self-fusion weld 10 of the connecting pipe. This arrangement allows the assembly and welding of the copper connecting pipe 4 to be independent of the large-sized main body component 1, meaning that the large-sized main body component 1 does not follow the welding and assembly of the copper connecting pipe 4. This arrangement not only improves welding efficiency and reduces welding difficulty and cost, but also gives the large-sized main body component 1 excellent versatility.

[0085] Based on the same design concept, this embodiment provides another large-diameter pipe connection structure. For example... Figure 22 and Figure 23 As shown, the large-diameter pipe connection structure provided in this embodiment includes a hollow main body 1, a stainless steel sleeve 3, and a copper connecting pipe 4. The main body 1 is a stainless steel pipe with an inner diameter greater than or equal to 18 mm. The front end of the stainless steel sleeve 3 and the shaft end 13 of the main body form a homogeneous metal assembly, and the assembly is connected by a self-fusion circumferential weld 20 or a self-fusion wire-feed circumferential weld. The copper connecting pipe 4 is inserted into the stainless steel sleeve 3, and a self-fusion weld and / or a brazed layer are formed between the stainless steel sleeve 3 and the copper connecting pipe 4. The self-fusion weld is a continuous circumferential weld or multiple spaced local welds formed by self-fusion welding or self-fusion wire-feed welding.

[0086] In the large-diameter pipe connection structure provided in this embodiment, the stainless steel main body 1 needs to be fitted with a copper connector 4 at its shaft end 13 to connect to the external system pipes. If the copper connector 4 is directly connected to the shaft end 13 of the main body, the two are usually brazed in a tunnel furnace. During welding, the large-sized main body not only occupies a large volume of tunnel furnace, affecting welding efficiency, but also the heat absorption of the large-sized main body during welding leads to a waste of welding heat. In this embodiment, the stainless steel sleeve 3 can be welded to the copper connector 4 first to form a self-fusion weld and / or a brazed layer for the connector. Then, the front end of the stainless steel sleeve 3 is welded to the shaft end 13 of the main body to form a self-fusion circumferential weld 20. This arrangement makes the assembly and welding of the copper connector 4 unaffected by the large-sized main body 1, greatly improving welding efficiency and reducing welding costs; at the same time, this arrangement also greatly facilitates the post-weld processing of the copper connector 4, such as cleaning. Furthermore, when the stainless steel sleeve 3 and the copper connector 4 are connected by other brazing methods such as self-fusion weld, brass brazing or high-frequency brazing, the grain size of the copper connector 4 will not be affected by long-term high temperature, thus giving it high strength and ductility.

[0087] Similarly, the connection method between the stainless steel sleeve 3 and the copper pipe 4 is basically the same as that in Embodiment 1, and will not be described again here.

[0088] Example 5

[0089] As described in Embodiment 1, the stainless steel sleeve 3 allows the processing of the connector component, composed of the copper connector 4 and the stainless steel sleeve 3, to be independent of the large-sized main body 1. This not only reduces the welding processes required for the main body 1, thus improving welding efficiency, but also makes the welding and assembly of the copper connector 4 more flexible. When the copper connector 4 and the stainless steel sleeve 3 are connected via the connector self-fusion weld 10, the copper connector 4 does not need to undergo prolonged high-temperature brazing in a furnace. Therefore, its grain size is not affected by welding, resulting in excellent strength, pressure resistance, and ductility.

[0090] Based on the same idea, this embodiment provides another large-diameter pipe connection structure. For example... Figure 24 As shown, the large-diameter pipe connection structure 100' provided in this embodiment includes a hollow main body 1, a receiving plate 2, a copper connecting sleeve 3', and a copper connecting pipe 4. The hollow main body 1 is made of stainless steel and has a through hole 11 on its peripheral wall that communicates with the inner cavity. The receiving plate 2 is welded to the outer peripheral wall of the main body 1, and a receiving hole 21 is formed on the receiving plate 2, which is substantially coaxial with the through hole 11 of the main body. The diameter Φ of the receiving hole 21 is greater than or equal to 18 mm and less than or equal to 65 mm. The front end of the copper connecting sleeve 3' is brazed to the receiving hole 21. The copper connecting pipe 4 is sleeved inside the copper connecting sleeve 3', and a self-fusion weld and / or a brazed layer 40' formed by non-furnace brazing is formed between the copper connecting sleeve 3' and the copper connecting pipe 4. The self-fusion weld is a continuous circumferential weld or multiple spaced local welds formed by self-fusion welding or self-fusion wire feeding welding.

[0091] In this embodiment, the diameter of the through hole 11 of the main body is smaller than the diameter of the receiving hole 21. The front end of the copper connecting sleeve 3' extends through the receiving hole 21 and abuts against the outer peripheral wall of the main body 1, which is attached to the through hole 11 of the main body. The main body 1, the receiving plate 2, and the copper connecting sleeve 3' are integrally welded together in a furnace. The peripheral wall of the copper connecting sleeve 3' is brazed to the receiving hole 21, and the front end face of the copper connecting sleeve 3' is brazed to the outer peripheral wall of the main body 1. In this structure, the outer peripheral wall of the main body 1 and the receiving hole 21 together provide the welding depth for the copper connecting sleeve 3'. However, this utility model does not limit this in any way. In other embodiments, the diameter of the receiving hole can also be set to be basically close to the diameter of the through hole of the main body. The front end of the copper connecting sleeve is inserted into the through hole of the main body through the receiving hole. The receiving hole and the through hole of the main body together provide the welding depth for the copper connecting sleeve to ensure that its welding strength meets the requirements of the refrigeration system. In this embodiment, the receiving hole is a through hole. However, this invention does not impose any limitations on this. In other embodiments, the receiving hole may also be a flanged hole to further increase the welding depth of the copper connecting sleeve.

[0092] In the large-diameter pipe connection structure provided in this embodiment, the copper connecting sleeve 3' allows for a homogeneous metal weld between it and the copper connecting pipe 4, providing conditions for independent welding of the copper connecting pipe 4, enabling it to be welded using a non-furnace brazing method. Specifically, in this embodiment, the copper connecting sleeve 3' and the copper connecting pipe 4 are welded using flame brazing to form a pipe brazing layer 40'. Compared to furnace brazing, flame brazing has a lower welding temperature and shorter heating time, preventing the grain size of the copper connecting pipe 4 from becoming coarse due to high-temperature and long-term welding. Therefore, after welding, the copper connecting pipe 4 still possesses excellent strength, pressure resistance, and ductility, making it well-suited not only for air conditioning systems with relatively low pressure but also for high-pressure refrigeration systems, such as low-temperature heat pump systems or cold storage systems using carbon dioxide refrigerant.

[0093] In this embodiment, although the grain size of the copper connecting sleeve 3' increases after furnace brazing, affecting its performance, the impact of furnace brazing on its strength and pressure resistance is significantly less than that of the copper connecting tube 4 because its length is much shorter than that of the copper connecting tube 4. Furthermore, during assembly, the high-strength copper connecting tube 4 is fitted onto the copper connecting sleeve 3', and both share the pressure at the overlapping joint, thereby greatly improving strength and pressure resistance. Preferably, the copper connecting tube 4 is inserted into the copper connecting sleeve 3', with the inserted end of the copper connecting tube 4 extending beyond the location of the receiving hole 21; this arrangement ensures that the copper connecting sleeve 3' does not bear pressure alone at any point, and its length can be shorter while meeting welding assembly requirements, thus resulting in higher strength.

[0094] Although this embodiment uses flame brazing as an example for illustration, the present invention does not limit itself in any way. In other embodiments, non-furnace brazing can also be high-frequency brazing or laser brazing, or other welding methods.

[0095] Although this embodiment uses the example of a copper connector inserted into a copper connecting sleeve, the present invention does not limit this. In other embodiments, the copper connector may also be fitted over the copper connecting sleeve. In this embodiment, the receiving plate 2 is a stainless steel receiving plate. However, the present invention does not limit this. In other embodiments, the receiving plate may also be a copper receiving plate.

[0096] Similarly, although this embodiment uses the example of a brazed layer 40' formed between the copper connecting sleeve 3' and the copper connecting pipe 4, this invention does not limit the scope of the invention. In other embodiments, the two can also be connected using a self-fusion weld (such as a self-fusion ring weld formed by argon arc welding); or, a combination of a self-fusion weld and a brazed layer can be used; in this case, the self-fusion weld is a ring weld or a partial weld.

[0097] In summary, the large-diameter pipe connection structure provided by this utility model, by adding a stainless steel receiving plate and a stainless steel sleeve, transforms the welding at the through-hole of the main component with limited assembly depth from traditional dissimilar metal welding of copper and steel to homogeneous metal welding of stainless steel, greatly reducing welding difficulty and effectively improving welding strength. Furthermore, the separate stainless steel receiving plate and stainless steel sleeve allow for independent processing. The stainless steel receiving plate can be formed through a simple stamping process, resulting in high forming efficiency and ensuring that its curvature matches the outer perimeter of the main component well, thus creating a uniform gap between the two that meets brazing requirements.

[0098] Furthermore, the use of stainless steel or copper connecting sleeves allows for independent assembly and welding of the copper pipe. Large main components do not need to be welded to the copper pipe, resulting in high welding efficiency, flexibility, and low cost. Simultaneously, the copper pipe remains unaffected by the welding of the main component, maintaining excellent strength and ductility. Moreover, the stainless steel or copper connecting sleeves remove the limitation of the copper pipe's assembly depth from the through-hole of the main component. For copper pipes of different diameters, simply adjusting the length of the stainless steel sleeve allows the assembly depth to meet the refrigeration system requirements, thus providing excellent versatility.

[0099] Although the present invention has been disclosed above by way of preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art may make some modifications and refinements without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the scope of protection claimed in the claims.

Claims

1. A large pipe diameter pipe connection structure characterized by, The utility model relates to a hollow main body piece made of stainless steel and having a main body piece through hole on the peripheral wall for communicating with the inner cavity; A stainless steel receiving plate is attached to the peripheral wall of the main body piece, and the stainless steel receiving plate has a receiving hole coaxial with the main body piece through hole, and the diameter of the receiving hole is greater than or equal to 18 mm and less than or equal to 65 mm; A stainless steel sleeve is inserted into the receiving hole to form a same metal assembly welding; A copper connecting pipe is inserted into the stainless steel sleeve, and a connecting pipe self-fluxing welding seam and / or a connecting pipe brazing layer are formed between the stainless steel sleeve and the copper connecting pipe, and the connecting pipe self-fluxing welding seam is a continuous ring welding seam or a plurality of locally distributed welding seams formed by self-fluxing welding or self-fluxing wire feeding welding. The connecting pipe self-fluxing welding seam is an electric arc welding seam formed by electric arc welding, and the electric arc welding seam is formed between at least one end of the stainless steel sleeve and the copper connecting pipe.

2. The large pipe diameter pipe connection structure according to claim 1, characterized by The sleeve assembly length L1 of the stainless steel sleeve and the copper connecting pipe is greater than or equal to the larger one of 0.05Φ and 2.5 mm, Φ is the diameter of the receiving hole, and a connecting pipe brazing layer is formed in the assembly gap between the two.

3. The large pipe diameter pipe connection structure according to claim 1, characterized by An exhaust hole for discharging gas is formed on the pipe wall of the copper connecting pipe and / or the pipe wall of the stainless steel sleeve in the sleeve overlapping area of the stainless steel sleeve and the copper connecting pipe.

4. The large pipe diameter pipe connection structure according to claim 3, characterized by The stainless steel sleeve is connected to the receiving hole and / or the main body piece through a steel sleeve brazing layer; 5. The large diameter pipe connection of claim 1, wherein, When the assembly gap between the stainless steel sleeve and the copper connecting pipe has a connecting pipe brazing layer, the steel sleeve brazing layer and the connecting pipe brazing layer are alloy layers formed by the same brazing filler metal; Alternatively, the connecting pipe brazing layer is an alloy layer formed by brazing filler metal with a liquidus lower than that of the steel sleeve brazing layer. A steel sleeve reinforcing welding seam for reinforcing the stainless steel sleeve is further formed between the peripheral wall of the stainless steel sleeve and the stainless steel receiving plate, and the steel sleeve reinforcing welding seam is a continuous ring welding seam or a plurality of locally distributed welding seams formed by self-fluxing welding or wire feeding welding.

6. The large pipe diameter pipe connection structure according to claim 5, characterized by The stainless steel sleeve is connected to the receiving hole through a self-fluxing ring welding seam or a self-fluxing wire feeding ring welding seam.

7. The large diameter pipe connection of claim 1, wherein The front end of the stainless steel sleeve extends through the receiving hole to abut against the peripheral wall of the main body piece near the main body piece through hole or is inserted into the main body piece through hole.

8. The large diameter pipe connection of claim 1, wherein, The diameter of the receiving hole is greater than the diameter of the main body piece through hole, and the difference between the diameters of the two is substantially close to or greater than the wall thickness of the front end of the stainless steel sleeve, and the end face of the front end of the stainless steel sleeve extends through the receiving hole to abut against the peripheral wall of the main body piece.

9. The large pipe diameter pipe connection structure according to claim 8, characterized by The main body piece is a pipe or a container with a cross section close to a circle, and the end face of the front end of the stainless steel sleeve is curved to be attached and welded to the peripheral wall of the main body piece.

10. The large pipe diameter pipe connection structure according to claim 9, characterized by The diameter of the receiving hole is substantially close to the diameter of the main body piece through hole, the front end of the stainless steel sleeve extends into the main body piece through hole through the receiving hole, and the front end of the stainless steel sleeve is further welded to the main body piece through hole.

11. The large pipe diameter pipe connection structure according to claim 8, characterized by The end face of the front end of the stainless steel sleeve is substantially flush with the inner wall of the main body piece; or the end face of the front end of the stainless steel sleeve extends into the inner cavity of the main body piece through the main body piece through hole.

12. The large pipe diameter pipe connection structure according to claim 11, characterized by A receiving plate reinforcing welding seam is formed between the edge of the stainless steel receiving plate and the peripheral wall of the main body piece, and the receiving plate reinforcing welding seam is a continuous ring welding seam or a plurality of locally distributed welding seams formed by self-fluxing welding or wire feeding welding.

13. The large diameter pipe connection of claim 1, wherein, The utility model relates to 14. A large pipe diameter pipe connection structure characterized by comprising: ​ The hollow main body is made of stainless steel and has a main body hole in the peripheral wall for communicating with the inner cavity, and a flange is formed on the main body hole, and the diameter of the hole at the flange is greater than or equal to 18 mm and less than or equal to 65 mm; The stainless steel sleeve is assembled with the flange in the same metal, and the assembly is connected by a self-fluxing ring weld or a self-fluxing wire ring weld; The copper connecting pipe is inserted into the stainless steel sleeve, and a connecting pipe self-fluxing weld and / or a connecting pipe brazing layer are formed between the stainless steel sleeve and the copper connecting pipe, and the connecting pipe self-fluxing weld is a continuous ring weld or a plurality of locally distributed partial welds formed by self-fluxing welding or self-fluxing wire welding.

15. A large pipe diameter pipe connection structure characterized by comprising: The hollow main body is made of stainless steel and has a main body hole in the peripheral wall for communicating with the inner cavity, and a flange is formed on the main body hole, and the diameter of the hole at the flange is greater than or equal to 18 mm and less than or equal to 65 mm; The stainless steel sleeve is assembled with the flange in the same metal, and the assembly is connected by a self-fluxing ring weld or a self-fluxing wire ring weld; The copper connecting pipe is inserted into the stainless steel sleeve, and a connecting pipe self-fluxing weld and / or a connecting pipe brazing layer are formed between the stainless steel sleeve and the copper connecting pipe, and the connecting pipe self-fluxing weld is a continuous ring weld or a plurality of locally distributed partial welds formed by self-fluxing welding or self-fluxing wire welding. The hollow main body is made of stainless steel and has a main body hole in the peripheral wall for communicating with the inner cavity, and a flange is formed on the main body hole, and the diameter of the hole at the flange is greater than or equal to 18 mm and less than or equal to 65 mm; 16. A large pipe line connection structure, characterized by The stainless steel sleeve is assembled with the flange in the same metal, and the assembly is connected by a self-fluxing ring weld or a self-fluxing wire ring weld; The copper connecting pipe is inserted into the stainless steel sleeve, and a connecting pipe self-fluxing weld and / or a connecting pipe brazing layer are formed between the stainless steel sleeve and the copper connecting pipe, and the connecting pipe self-fluxing weld is a continuous ring weld or a plurality of locally distributed partial welds formed by self-fluxing welding or self-fluxing wire welding. The large-diameter pipe connecting structure of any one of claims 1-16. The large-diameter pipe connecting structure of any one of claims 1-16. ​ 17. A refrigeration kit, characterized in that, ​ 18. A refrigeration system characterized by, ​

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