Pipe connection assembly, refrigeration device and refrigeration system

Abstract

This utility model provides a pipe connection assembly, a refrigeration device, and a refrigeration system. The pipe connection assembly includes a first pipe fitting made of copper or a copper alloy, a second pipe fitting made of aluminum or an aluminum alloy, and a transition pipe connecting the first and second pipe fittings. The transition pipe has a lower electrical conductivity and a lower coefficient of linear expansion than the second pipe fitting. Both ends of the transition pipe are inserted into the first and second pipe fittings, respectively. The outer wall of the transition pipe has an outwardly protruding annular barrier portion located between the ends of the first and second pipe fittings, which blocks the ends of both pipe fittings at any point in its circumference.

Description

Technical Field

[0001] This utility model relates to the field of refrigeration accessories, and in particular to a pipeline connection component, a refrigeration device, and a refrigeration system. Background Technology

[0002] Traditional refrigeration components are mostly made of copper, a material with high thermal conductivity. However, the continuous rise in copper prices has prompted the refrigeration industry to seek steel and aluminum as substitutes for copper to reduce material costs; and compared to steel, aluminum has thermal conductivity and plasticity closer to copper; therefore, aluminum refrigeration components (such as aluminum heat exchangers and aluminum refrigerant distributors) have begun to appear on the market. However, due to limitations in on-site installation conditions, current refrigeration system piping is still mainly copper piping, and copper pipes are installed on-site using mature manual flame brazing, which requires aluminum refrigeration components to be welded to copper pipes. Since the refrigeration system piping will be in contact with humid environments, condensate, chemical gases, and salts for extended periods during operation, it is in an electrolyte environment for a long time. Both copper and aluminum are materials with relatively high electrical conductivity (aluminum's conductivity is about 60% of copper's); in an electrolyte environment, copper and aluminum will form electrodes, creating a galvanic cell effect. Aluminum, with its lower potential, acts as the anode and undergoes an oxidation reaction, leading to ion dissolution and electrochemical corrosion, severely affecting the strength and service life of the copper-aluminum pipe connections.

[0003] To address this issue, Chinese patent CN212643809U proposes a corrosion-resistant copper-aluminum joint. This design involves adding a stainless steel connecting sleeve to the outside of the copper and aluminum tubes. The stainless steel connecting sleeve includes a sleeve body and a partition plate located inside the sleeve body. The copper and aluminum tubes are inserted into the two ends inside the sleeve body, and both are connected to the limiting grooves at both ends of the partition plate via annular protrusions and limiting plates, thus positioning the copper and aluminum tubes without them coming into contact. While this method can alleviate the electrochemical corrosion problem caused by the galvanic cell effect between copper and aluminum, both the setting of the partition plate inside the sleeve body and the connection between the copper and aluminum tubes and the partition plate present significant challenges in processing, including high processing difficulty, complex procedures, and high costs. More importantly, the linear expansion coefficient of aluminum is much greater than that of stainless steel, with an expansion coefficient of 23.8 × 10⁻⁶. -6 / ℃, while the coefficient of linear expansion of stainless steel is 16×10. -6 / ℃; After the stainless steel pipe connecting sleeve is welded to the aluminum pipe, the stress generated by the aluminum pipe cooling and shrinking inward will cause severe tensile stress in the weld between the stainless steel pipe connecting sleeve and the aluminum pipe, leading to weld cracking and subsequent welding leakage problems. Utility Model Content

[0004] In order to overcome the shortcomings of the prior art, this utility model provides a pipeline connection component, a refrigeration device, and a refrigeration system.

[0005] To achieve the above objectives, the first aspect of this utility model provides a pipe connection assembly, comprising a first pipe fitting made of copper or a copper alloy, a second pipe fitting made of aluminum or an aluminum alloy, and a transition pipe connecting the first and second pipe fittings. The transition pipe has a lower electrical conductivity and a lower coefficient of linear expansion than the second pipe fitting. Both ends of the transition pipe are inserted into the first and second pipe fittings, respectively. An annular blocking portion protruding outwards and located between the ends of the first and second pipe fittings is provided on the outer wall of the transition pipe. This annular blocking portion blocks the ends of the first and second pipe fittings at any point in its circumference.

[0006] According to one embodiment of the present invention, the cross-section of the annular barrier is close to a circle, and its outer diameter is greater than the outer diameter of the end of the first pipe fitting and / or the outer diameter of the end of the second pipe fitting.

[0007] According to an embodiment of the first aspect of the present invention, the annular barrier is an isolation ring that is sleeved on the outer wall of the transition pipe, and the two ends of the isolation ring abut against the ends of the first pipe fitting and the second pipe fitting, respectively; the isolation ring is an integral structure; or, the isolation ring includes a plurality of isolation ring pieces that are sequentially overlapped and connected.

[0008] According to an embodiment of the first aspect of the present invention, the isolation ring is welded to any one of the outer wall of the transition pipe, the end of the first pipe fitting, or the end of the second pipe fitting.

[0009] According to an embodiment of the first aspect of the present invention, the annular barrier portion is integrally formed on the outer wall of the transition tube.

[0010] According to one embodiment of the first aspect of the present invention, both the transition tube and the annular barrier are made of carbon steel; or, both are made of alloy steel.

[0011] According to an embodiment of the first aspect of the present invention, a coating is formed on the outer peripheral wall of the transition pipe connected to the second pipe fitting. The coating is an aluminum layer, a nickel layer, or a zinc layer.

[0012] According to an embodiment of the first aspect of the present invention, one end of the transition tube is connected to the first pipe fitting by furnace brazing, and the other end is connected to the second pipe fitting by high-frequency induction brazing or laser brazing.

[0013] A second aspect of this utility model also provides a refrigeration device including the above-mentioned pipeline connection components.

[0014] A second aspect of this invention also provides a refrigeration system including the aforementioned pipe connection components and / or refrigeration devices.

[0015] In summary, in the pipe connection assembly provided by this utility model, the two ends of the transition pipe are respectively inserted into the first pipe fitting and the second pipe fitting, and the ends of the first pipe fitting and the second pipe fitting are separated from each other by a protruding annular barrier on the outer wall of the transition pipe, preventing direct contact. This design effectively solves the electrochemical corrosion problem caused by the galvanic cell effect when copper and aluminum are in direct contact, thus significantly extending the service life of the pipe connection. The annular barrier not only has a simple structure but also serves as a positioning reference for both ends of the transition pipe, greatly simplifying the assembly process.

[0016] More importantly, among the first fitting, the second fitting, and the transition pipe, the transition pipe has the smallest coefficient of linear expansion. After welding, the shrinkage of both the first and second fittings is greater than that of the transition pipe. During cooling and shrinkage, compressive stress pointing towards the center of the transition pipe will be generated at the welds at both ends. This compressive stress is opposite to the direction of the external load on the pipe connection assembly. The superposition of these two stresses significantly reduces the effective stress actually borne by the pipe connection assembly, thereby significantly improving its load-bearing capacity. In addition, the compressive stress can also reduce the surface free energy of the transition pipe, effectively inhibiting corrosion at the weld, further enhancing the connection strength of the welds at both ends of the transition pipe and extending its service life.

[0017] 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

[0018] Figure 1 The diagram shown is a structural schematic of a pipeline connection assembly provided in an embodiment of this utility model.

[0019] Figure 2 The diagram shown is a structural schematic of a pipeline connection assembly provided in another embodiment of this utility model.

[0020] Figure 3A The diagram shown is a structural schematic of a pipeline connection assembly provided in another embodiment of this utility model.

[0021] Figure 3B The diagram shown is a structural schematic of a pipeline connection assembly provided in another embodiment of this utility model.

[0022] Figure 4 As shown Figure 1 A partial schematic diagram of the piping connection components assembled within a refrigeration unit or system.

[0023] Figure 5 The diagram shown is a structural schematic of a pipe connection assembly formed on a refrigeration device according to another embodiment of the present invention.

[0024] Figure 6 As shown Figure 5 Enlarged diagram of point A in the middle. Detailed Implementation

[0025] To address the electrochemical corrosion problem caused by direct contact between copper and aluminum in refrigeration systems, some researchers have proposed adding stainless steel connecting sleeves to the outside of the copper and aluminum pipes, using a partition inside the stainless steel connecting sleeve to isolate the copper and aluminum pipes. While this arrangement effectively solves the electrochemical corrosion problem, it suffers from low weld strength at both ends of the stainless steel sleeve, susceptibility to leakage, and easy corrosion of the steel at the weld joints. Therefore, this embodiment provides a corrosion-resistant and high-strength pipe connection assembly for connecting copper and aluminum pipes.

[0026] like Figure 1 As shown, the pipe connection assembly 300 provided in this embodiment includes a first pipe fitting 1 made of copper or copper alloy, a second pipe fitting 2 made of aluminum or aluminum alloy, and a transition pipe 3 connecting the first pipe fitting 1 and the second pipe fitting 2. The electrical conductivity and coefficient of linear expansion of the transition pipe 3 are both lower than those of the second pipe fitting 2. Both ends of the transition pipe 3 are inserted into the first pipe fitting 1 and the second pipe fitting 2, respectively. An annular blocking portion 31, protruding outwards and located between the end 11 of the first pipe fitting and the end 21 of the second pipe fitting, is provided on the outer wall of the transition pipe 3. The annular blocking portion 31 blocks the end 11 of the first pipe fitting and the end 21 of the second pipe fitting at any point in its circumference.

[0027] In the pipe connection assembly 300 provided in this embodiment, the annular barrier 31 protruding on the outer wall of the transition pipe 3 makes it difficult for electrolyte to continuously adhere at its bends or on the protruding surface parallel to the direction of gravity. This makes it difficult to directly establish a current loop between the first pipe end 11 and the second pipe end 21, thus preventing the formation of a galvanic cell effect. Furthermore, since the conductivity of the transition pipe 3 is lower than that of the second pipe 2 made of aluminum or aluminum alloy (the conductivity of aluminum is also lower than that of copper), electrons are also less likely to form an indirect current loop between the first pipe end 11 and the second pipe end 21 through the transition pipe 3. Therefore, it can effectively reduce electrochemical corrosion caused by the potential difference between the first and second pipes, thereby extending the service life of the pipe. Compared to existing copper-aluminum joints with a baffle inside the stainless steel pipe connecting sleeve, the pipe connection assembly 300 provided in this embodiment inserts both ends of the transition pipe 3 into the first pipe 1 and the second pipe 2 respectively, so that the annular barrier 31 can be disposed on the outer wall of the transition pipe 3. The external annular barrier 31 is not only simple to form and easy to form; but also, since its forming position on the outer wall of the transition pipe 3 is not restricted, it can also be directly used as the assembly positioning at both ends of the transition pipe 3. There is no need to set other assembly positioning structures on the transition pipe 3 and the two pipe fittings. The connection of the three can be achieved simply by fitting them together, which further simplifies the structure of the pipeline connection component 300 and its forming difficulty.

[0028] Furthermore, the internal insertion assembly method of the transition pipe 3 at both ends ensures that its weld seams not only have excellent load-bearing capacity but also corrosion resistance. Specifically, the linear expansion coefficient of the transition pipe 3 is lower than that of the second fitting 2 made of aluminum or aluminum alloy, and the linear expansion coefficient of the second fitting 2 is lower than that of the first fitting 1 made of copper or copper alloy; that is, among the first fitting 1, the second fitting 2, and the transition pipe 3, the transition pipe 3 has the lowest linear expansion coefficient, resulting in the smallest shrinkage after welding and cooling. After welding, the first fitting 1 and the second fitting 2 shrink, generating compressive stress pointing towards the center of the transition pipe 3 at the weld seams at both ends. In the refrigeration system piping, the piping connection assembly 300 inevitably needs to bear refrigerant pressure loads and tensile loads from adjacent piping. The directions of these loads are all away from the center direction of the transition pipe 3, i.e., opposite to the direction of the compressive stress at the weld seams. When the compressive stress at the weld seams is superimposed on these loads, the opposing forces partially cancel each other out, greatly reducing the effective stress actually borne by the weld seams at both ends of the transition pipe 3 and significantly improving the load-bearing capacity of the weld seams at both ends. Furthermore, the compressive stress acting on both ends of the transition tube 3 will reduce the interatomic spacing on the surface of the transition tube 3, strengthen the interatomic bonding force, and tend to a more stable state. This stable state gives the metal atoms on the surface of the transition tube 3 a lower free energy, making them less likely to lose electrons and undergo electrochemical corrosion in an electrolyte environment, thus giving the welds at both ends of the transition tube 3 excellent corrosion resistance.

[0029] Based on the isolation of the first pipe fitting 1 and the second pipe fitting 2 by the annular barrier 31 and the excellent load-bearing capacity and corrosion resistance of the welds at both ends of the transition pipe 3, the pipe connection assembly 300 formed between copper and aluminum pipes provided in this embodiment is not only simple in structure and has high pipe connection strength, but also has corrosion resistance at each connection and a long service life.

[0030] In this embodiment, the transition tube 3 is a stainless steel tube with a conductivity and coefficient of linear expansion both significantly lower than that of the second fitting 2. However, this invention does not impose any limitations on this. In other embodiments, the transition tube may also be a carbon steel tube or other steel alloy tube. In this embodiment, the first fitting 1 and the second fitting 2 at both ends of the transition tube 3 are connected by brazing. Specifically, one end of the transition tube 3 is brazed in a furnace to the first fitting 1 made of copper or copper alloy, such as using tin bronze in a furnace; while the other end of the transition tube 3 is welded using a steel-aluminum brazing process. Since brittle intermetallic compounds are easily formed at the weld seam after direct brazing of steel and aluminum, it is preferable to use rapid heating welding such as high-frequency induction brazing or laser brazing to control the brittle layer within a very thin range to improve the weld strength between the transition tube 3 and the second fitting 2. However, this invention does not impose any limitations on this. In other embodiments, a coating may also be formed on the outer peripheral wall region of the transition pipe connected to the second pipe fitting 2. This coating helps prevent the formation of brittle intermetallic compounds, thereby improving the weld strength between the transition pipe and the second pipe fitting. Alternatively, in other embodiments, self-fusion welding (such as laser welding) may be used to weld the first pipe fitting, the transition pipe, and the second pipe fitting.

[0031] In this embodiment, the cross-section of the annular barrier portion 31 is nearly circular, and its outer diameter is larger than the outer diameter of the first pipe end 11 and the second pipe end 21, respectively. However, this invention does not impose any limitation on this. In other embodiments, the outer diameter of the annular barrier portion may only be larger than the outer diameter of the first pipe end or the second pipe end. In other embodiments, the cross-section of the annular barrier portion may also be of other shapes, such as polygons.

[0032] In this embodiment, the annular barrier 31 is an integral isolation ring that is sleeved on the transition tube 3. The first tube end 11 and the second tube end 21 respectively abut against the two ends of the isolation ring, and the isolation ring is fixed to the outer peripheral wall of the transition tube 3 while being assembled and positioned based on the two ends of the isolation ring. However, this utility model does not impose any limitations on this. In other embodiments, the isolation ring may also include multiple sequentially stacked sub-isolation ring pieces, such as Figure 2 As shown. Furthermore, this utility model does not limit the method of fixing the isolation ring. In other embodiments, the isolation ring can also be fixed to any one of the outer wall of the transition pipe, the end of the first pipe fitting, or the end of the second pipe fitting by welding.

[0033] In this embodiment, the material of the annular barrier 31 is the same as that of the transition tube 3, both being made of stainless steel. However, this invention does not impose any limitations on this. In other embodiments, the annular barrier may also be made of carbon steel or other alloy steel. Although this embodiment uses the annular barrier 31 as a separate insulating ring fitted over the transition tube 3 as an example, this invention does not impose any limitations on this. In other embodiments, the annular barrier may also be integrally formed on the outer wall of the transition tube; specifically, it can be machined (e.g., by machining). Figure 3A (as shown) or cold heading (such as) Figure 3B As shown, an annular barrier 31 is integrally formed on the transition tube 3.

[0034] Correspondingly, this embodiment also provides a refrigeration device including the aforementioned pipe connection assembly 300. Specifically, the refrigeration device may be a refrigerant distributor connected between the expansion valve and the heat exchange assembly; or a water distributor / manifold installed at the end of a fan coil unit. However, this utility model does not limit this in any way, and the pipe connection assembly 300 provided in this embodiment can be used in other situations requiring copper-aluminum connections.

[0035] On the other hand, this embodiment also provides a refrigeration system including the above-mentioned pipe connection assembly 300 and / or refrigeration device.

[0036] Figure 4 The diagram shows a partial view of the pipe connection assembly 300 provided in this embodiment installed in a refrigeration system. In this structure, the pipe connection assembly 300 is an independent component. A first pipe fitting 1 made of copper or copper alloy is connected to a copper pipe 100 on the refrigeration system or refrigeration device by flame brazing. A second pipe fitting 2 made of aluminum or aluminum alloy is connected to an aluminum pipe 200 on another refrigeration device (such as an aluminum heat exchanger) by any one of TIG (tungsten inert gas welding), MIG (methane inert gas welding), laser beam welding, or friction stir welding.

[0037] However, this invention does not limit the scope of the invention in any way. In other embodiments, the piping connection assembly may also be part of the refrigeration device. Specifically, such as Figure 5 and Figure 6As shown, the refrigeration device is a refrigerant distributor, and the pipe connection assembly 300 is part of the refrigerant distributor branch pipe. One end of the second pipe fitting 2 is connected to the distributor body 400 via an aluminum short connecting pipe 401 (or, one end of the second pipe fitting 2 is directly connected to the distributor body 400), and the other end is connected to the transition pipe 3. The first pipe fitting 1, made of copper or copper alloy, serves as the assembly end of the refrigerant distributor to connect to external copper pipes or other copper refrigeration devices (such as copper heat exchangers). Similarly, in other embodiments, the first pipe fitting can be used to connect to other components of the copper refrigeration device, while the second pipe fitting, made of aluminum or aluminum alloy, serves as the assembly end of the copper refrigeration device to connect to external aluminum pipes or other aluminum refrigeration devices.

[0038] In summary, in the pipe connection assembly provided by this utility model, the two ends of the transition pipe are respectively inserted into the first pipe fitting and the second pipe fitting, and the ends of the first pipe fitting and the second pipe fitting are separated from each other by a protruding annular barrier on the outer wall of the transition pipe, preventing direct contact. This design effectively solves the electrochemical corrosion problem caused by the galvanic cell effect when copper and aluminum are in direct contact, thus significantly extending the service life of the pipe connection. The annular barrier not only has a simple structure but also serves as a positioning reference for both ends of the transition pipe, greatly simplifying the assembly process.

[0039] More importantly, among the first fitting, the second fitting, and the transition pipe, the transition pipe has the smallest coefficient of linear expansion. After welding, the shrinkage of both the first and second fittings is greater than that of the transition pipe. During cooling and shrinkage, compressive stress pointing towards the center of the transition pipe will be generated at the welds at both ends. This compressive stress is opposite to the direction of the external load on the pipe connection assembly. The superposition of these two stresses significantly reduces the effective stress actually borne by the pipe connection assembly, thereby significantly improving its load-bearing capacity. In addition, the compressive stress can also reduce the surface free energy of the transition pipe, effectively inhibiting corrosion at the weld, further enhancing the connection strength of the welds at both ends of the transition pipe and extending its service life.

[0040] 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 pipe connection assembly, characterized in that, include: A first fitting made of copper or a copper alloy, a second fitting made of aluminum or an aluminum alloy, and a transition pipe connecting the first fitting and the second fitting; The conductivity and coefficient of linear expansion of the transition tube are both lower than those of the second fitting. The two ends of the transition tube are inserted into the first fitting and the second fitting, respectively. The outer wall of the transition tube is provided with an outwardly protruding annular barrier located between the ends of the first fitting and the second fitting. The annular barrier blocks the ends of the first fitting and the second fitting at any point in its circumference.

2. The pipeline connection assembly according to claim 1, characterized in that, The cross-section of the annular barrier is nearly circular, and its outer diameter is greater than the outer diameter of the end of the first pipe fitting and / or the outer diameter of the end of the second pipe fitting.

3. The pipeline connection assembly according to claim 1, characterized in that, The annular barrier is an isolation ring that is sleeved on the outer wall of the transition pipe, and the two ends of the isolation ring abut against the ends of the first pipe fitting and the second pipe fitting, respectively; the isolation ring is an integral structure; or, the isolation ring includes a plurality of isolation ring pieces that are connected in a sequentially overlapping manner.

4. The pipeline connection assembly according to claim 3, characterized in that, The isolation ring is welded to any one of the outer wall of the transition pipe, the end of the first fitting, or the end of the second fitting.

5. The pipeline connection assembly according to claim 1, characterized in that, The annular barrier is integrally formed on the outer wall of the transition tube.

6. The pipeline connection assembly according to claim 1, characterized in that, The transition tube and the annular barrier are both made of carbon steel; or, both are made of alloy steel.

7. The pipe connection assembly according to claim 1 or 6, characterized in that, A coating is formed on the outer peripheral wall of the transition pipe connected to the second pipe fitting. The coating is an aluminum layer, a nickel layer, or a zinc layer.

8. The pipe connection assembly according to claim 1 or 6, characterized in that, One end of the transition tube is connected to the first pipe fitting by furnace brazing, and the other end is connected to the second pipe fitting by high-frequency induction brazing or laser brazing.

9. A refrigeration device, characterized in that, Includes the pipe connection assembly as described in claim 1.

10. A refrigeration system, characterized in that, Includes the piping connection assembly as described in claim 1 and / or the refrigeration device as described in claim 9.

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