Gas return pipe and heating and ventilation device with same

Abstract

The utility model discloses a kind of back gas pipe and heating and ventilation device with it, back gas pipe includes first back gas pipe and second back gas pipe, first back gas pipe is connected between compressor and gas-liquid separator, second back gas pipe is connected between gas-liquid separator and four-way valve component, first back gas pipe and / or second back gas pipe have multiple bending parts, wherein, first back gas pipe and / or second back gas pipe are flexible stainless steel integrally-formed stainless steel pipe.According to the back gas pipe of the utility model, first back gas pipe and / or second back gas pipe are flexible stainless steel integrally-formed stainless steel pipe, stainless steel pipe is higher in strength, and have lower yield strength and higher ductility, can improve the reliability in the working process of back gas pipe, and design difficulty and assembly difficulty of heating and ventilation device can be reduced, improve assembly efficiency.

Description

Technical Field

[0001] This utility model relates to the field of heating, ventilation and air conditioning (HVAC), and in particular to a return air pipe and an HVAC device having the same. Background Technology

[0002] The HVAC system includes a return pipe, which is used to transport the refrigerant from the evaporator after heat exchange to the compressor. In related technologies, when the refrigerant flows in the return pipe, it impacts the pipe. Additionally, the compressor vibrates during HVAC operation, resulting in low reliability of the return pipe. Utility Model Content

[0003] The present invention aims to at least solve one of the technical problems existing in the prior art. Therefore, one objective of the present invention is to provide a return gas pipe, which is a flexible stainless steel pipe integrally formed, to improve the reliability of the return gas pipe during operation.

[0004] This utility model also proposes a heating and ventilation device having the above-mentioned return air pipe.

[0005] According to a first aspect of the present invention, a return pipe includes a first return pipe and a second return pipe. The first return pipe is connected between a compressor and a gas-liquid separator, and the second return pipe is connected between the gas-liquid separator and a four-way valve assembly. The first return pipe and / or the second return pipe have multiple bends. The first return pipe and / or the second return pipe are integrally formed stainless steel pipes made of flexible stainless steel.

[0006] According to the embodiments of the present invention, the first return pipe and / or the second return pipe are integrally formed stainless steel pipes made of flexible stainless steel. Stainless steel pipes have high strength, lower yield strength and higher ductility, which can improve the reliability of the return pipe during operation, reduce the design and assembly difficulty of HVAC devices, and improve assembly efficiency.

[0007] According to some embodiments of the present invention, the first return pipe and / or the second return pipe includes a plurality of straight pipes, and the bent portion is connected between two adjacent straight pipes.

[0008] According to some embodiments of this utility model, the bent portion is an arc.

[0009] According to some embodiments of the present invention, the first return pipe includes a first pipe and a second pipe connected together. The first pipe includes a first straight pipe, a second straight pipe and a bent pipe. The bent pipe is connected between the first straight pipe and the second straight pipe. The end of the second straight pipe away from the bent pipe is connected to the second pipe.

[0010] According to some embodiments of the present invention, the bending portion is provided between the second pipe and the first pipe.

[0011] According to some embodiments of this utility model, the diameters of the first straight pipe and the second straight pipe are both d, and the bending radius of the bent pipe is r, satisfying 1.2d≤r≤1.5d.

[0012] According to some embodiments of the present invention, the second return air pipe includes multiple pipe segments, and the bent portion is connected between two adjacent pipe segments. The multiple pipe segments are a first pipe segment, a second pipe segment, a third pipe segment, a fourth pipe segment, and a fifth pipe segment connected in sequence. The first pipe segment, the third pipe segment, and the fifth pipe segment all extend along a first direction, and the second pipe segment and the fifth pipe segment extend along a second direction. The first direction and the second direction are perpendicular to each other.

[0013] According to some embodiments of the present invention, an expansion tube is provided at one end of the first return air pipe and / or the second return air pipe, the diameter of the expansion tube being larger than the diameter of the straight pipe; and a retraction tube is provided at the other end of the first return air pipe and / or the second return air pipe, the diameter of the retraction tube being smaller than the diameter of the straight pipe; or, expansion tubes are provided at both ends of the first return air pipe and / or the second return air pipe, the diameter of the expansion tube being larger than the diameter of the straight pipe; or, retraction tubes are provided at both ends of the first return air pipe and / or the second return air pipe, the diameter of the retraction tube being smaller than the diameter of the first straight pipe.

[0014] According to some embodiments of the present invention, the expansion tube includes at least one sub-expansion tube. When there are multiple sub-expansion tubes, the multiple sub-expansion tubes are connected in sequence, and the diameters of the multiple sub-expansion tubes increase in sequence in the direction from the bend to the straight tube; and / or, the retraction tube includes at least one sub-retraction tube. When there are multiple sub-retraction tubes, the multiple sub-retraction tubes are connected in sequence, and the diameters of the multiple sub-retraction tubes decrease in sequence in the direction from the bend to the straight tube.

[0015] According to some embodiments of the present invention, a limiting part that cooperates with the external piping is provided at one end of the first return pipe and / or the second return pipe; or, a limiting part that cooperates with the external piping is provided at both ends of the first return pipe and / or the second return pipe.

[0016] According to some embodiments of the present invention, the limiting part is a convex bulge or an annular protrusion extending around the axis of the straight tube (103).

[0017] According to some embodiments of the present invention, the yield strength of the flexible stainless steel is 140-180 MPa; and / or, the tensile strength of the flexible stainless steel is reduced to 400-600 MPa; and / or, the elongation of the flexible stainless steel is 50-80%; and / or, the yield strength ratio of the flexible stainless steel is less than 0.4; and / or, the hardness of the flexible stainless steel material is 100-120 Hv.

[0018] According to some embodiments of this utility model, the Md30 of the flexible stainless steel is -50℃ to -80℃.

[0019] According to some embodiments of the present invention, the flexible stainless steel is austenitic stainless steel, and the average grain size of the flexible stainless steel is 20μm to 40μm.

[0020] According to some embodiments of this utility model, the wall thickness of the stainless steel pipe is 1.2mm to 1.5mm.

[0021] According to some embodiments of the present invention, one or both ends of the first return gas pipe or the second return gas pipe are connected to external piping, and the first return gas pipe, the second return gas pipe and the external piping are all integrally formed stainless steel pipes of flexible stainless steel.

[0022] According to some embodiments of the present invention, one or both ends of the first return gas pipe or the second return gas pipe are connected to external piping. The first return gas pipe and the second return gas pipe are stainless steel pipes integrally formed from flexible stainless steel, and the external piping is a copper pipe or a copper alloy pipe.

[0023] According to some embodiments of the present invention, one or both ends of the first return gas pipe or the second return gas pipe are connected to external piping, one or both ends of the first return gas pipe or the second return gas pipe are provided with a first sleeve, and one or both ends of the first return gas pipe or the second return gas pipe are provided with a second sleeve, wherein the first sleeve and the second sleeve are both copper pipes or copper alloy pipes.

[0024] The HVAC device according to a second aspect of the present invention includes: a compressor, a gas-liquid separator, and a four-way valve assembly. According to the first aspect of the present invention, the return pipe includes a first return pipe and a second return pipe. The first return pipe is connected between the compressor and the gas-liquid separator, and the second return pipe is connected between the gas-liquid separator and the four-way valve assembly.

[0025] According to the HVAC device of the present utility model embodiment, by setting the above-mentioned return air pipe, on the one hand, the effect of the HVAC device can be improved and the reliability of the HVAC device during operation can be increased; on the other hand, the difficulty of the HVAC device production and design process can be reduced and the production efficiency can be improved.

[0026] Additional aspects and advantages of this invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0027] The above and / or additional aspects and advantages of this utility model will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0028] Figure 1 This is a schematic diagram showing the connection between the return pipe and the compressor, the gas-liquid separator and the four-way valve assembly according to some embodiments of the present invention;

[0029] Figure 2 This is a schematic diagram showing the connection between the first return gas pipe and the external piping according to the first embodiment of this utility model;

[0030] Figure 3 yes Figure 2 A magnified schematic diagram of a portion at point A shown in the image;

[0031] Figure 4 This is a schematic diagram showing the connection between the first return gas pipe and the external piping according to the second embodiment of the present invention;

[0032] Figure 5 yes Figure 4 A magnified schematic diagram of a portion at point B shown in the image;

[0033] Figure 6 This is a schematic diagram showing the connection between the first return gas pipe and the external piping according to the third embodiment of this utility model;

[0034] Figure 7 yes Figure 6 A magnified schematic diagram of a portion at point C shown in the image;

[0035] Figure 8 This is a schematic diagram showing the connection between the second return gas pipe and the external piping according to the first embodiment of this utility model;

[0036] Figure 9 yes Figure 8 A magnified schematic diagram of a portion at point D shown in the image;

[0037] Figure 10 This is a schematic diagram showing the connection between the second return gas pipe and the external piping according to the second embodiment of the present invention;

[0038] Figure 11 yes Figure 10 A magnified schematic diagram of a portion at point E shown in the image;

[0039] Figure 12 This is a schematic diagram showing the connection between the second return gas pipe and the external piping according to the third embodiment of this utility model;

[0040] Figure 13 yes Figure 12 The diagram shows a magnified view of a portion of point F.

[0041] Figure label:

[0042] 100. Compressor; 200. Gas-liquid separator; 300. Four-way valve assembly;

[0043] 10. Return air pipe; 101. First return air pipe; 102. Second return air pipe; 103. Straight pipe

[0044] 1. First piping; 11. First straight pipe; 12. Second straight pipe; 13. Bent pipe;

[0045] 2. Second piping; 21. First pipe section; 22. Second pipe section; 23. Third pipe section; 24. Fourth pipe section; 25. Fifth pipe section;

[0046] 3. Bending section; 41. First sleeve; 42. Second sleeve; 51. First solder; 52. Second solder; 53. Third solder; 54. Fourth solder;

[0047] 6. External piping. Detailed Implementation

[0048] The embodiments of this utility model are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this utility model, and should not be construed as limiting this utility model.

[0049] In the description of this utility model, it should be understood that the terms "upper," "lower," "front," "rear," "left," and "right," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used solely for the convenience of describing this utility model and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this utility model, "a plurality of" means two or more, unless otherwise explicitly specified.

[0050] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0051] The following is for reference. Figures 1-13 The air return pipe 10 is described according to an embodiment of the present invention.

[0052] According to the first aspect of the present invention, the return pipe 10 includes a first return pipe 101 and a second return pipe 102. One end of the first return pipe 101 is connected between the compressor 100 and the gas-liquid separator 200. The second return pipe 102 is connected between the gas-liquid separator 200 and the four-way valve assembly 300. The refrigerant is delivered to the second return pipe 102 through the four-way valve assembly 300, reaches the gas-liquid separator 200 through the second return pipe 102, and after separation in the gas-liquid separator 200, reaches the compressor 100 through the first return pipe 101.

[0053] The first return air pipe 101 and / or the second return air pipe 102 have multiple bends 3. Specifically, the first return air pipe 101 may have multiple bends 3; the second return air pipe 102 may have multiple bends 3; or both the first return air pipe 101 and the second return air pipe 102 may have multiple bends 3. The first return air pipe 101 and / or the second return air pipe 102 are integrally formed flexible stainless steel pipes. Specifically, the first return air pipe 101 may be integrally formed flexible stainless steel pipe; the second return air pipe 102 may be integrally formed flexible stainless steel pipe; or both the first return air pipe 101 and the second return air pipe 102 may be integrally formed flexible stainless steel pipes.

[0054] When the refrigerant flows within the return pipe 10, it impacts the return pipe 10. Simultaneously, the compressor 100 vibrates during HVAC operation. In this application, the first return pipe 101 and / or the second return pipe 102 are integrally formed flexible stainless steel pipes. Stainless steel pipes have high strength and can withstand the high-intensity impacts from the compressor 100 and the refrigerant, thereby improving the reliability of the return pipe 10 during operation. Furthermore, bending portions 3 are provided on the first return pipe 101 and / or the second return pipe 102. Bending the first return pipe 101 and / or the second return pipe 102 reduces the vibration experienced by the return pipe 10.

[0055] The first return air pipe 101 and / or the second return air pipe 102 are manufactured using a flexible stainless steel one-piece molding process, which increases the structural strength of the first return air pipe 101 and / or the second return air pipe 102 while reducing the manufacturing cost. The first return air pipe 101 and / or the second return air pipe 102 are made of stainless steel, which has lower yield strength and higher ductility. This makes the first return air pipe 101 and / or the second return air pipe 102 easier to bend, allowing for a smaller bending radius at the bending portion 3 and reducing the likelihood of cracking on the outer side and wrinkling on the inner side of the bending portion 3.

[0056] Flexible stainless steel is copper-containing stainless steel. The presence of copper gives stainless steel better ductility and flexibility because copper forms fine, dispersed phases within the stainless steel, hindering dislocation movement and thus increasing the material's yield strength. Furthermore, appropriate amounts of copper can refine the grains, reducing defects at grain boundaries and improving the material's toughness. Additionally, the addition of copper can induce a martensitic phase transformation, further enhancing the stainless steel's strength. It is understandable that stainless steel pipes are easier to bend than conventional stainless steel pipes. In HVAC system design, to achieve a more compact structure, the space for the first return air pipe 101 and / or the second return air pipe 102 should not be excessive. In this application, the first return air pipe 101 and / or the second return air pipe 102 are integrally formed flexible stainless steel pipes. When bending these pipes, their bending limit is greater. Therefore, during HVAC system design, it is easier to arrange the stainless steel pipes within the designated space when the layout changes, thereby reducing the design complexity of the HVAC system.

[0057] During the process of assembling the return pipe 10 onto the HVAC system, the operating space around the return pipe 10 is often small. Stainless steel pipes are easier to adjust during assembly, which reduces the operator's difficulty of operation, thereby reducing assembly difficulty and improving assembly efficiency.

[0058] In addition, stainless steel has strong chemical stability, and stainless steel pipes can better resist corrosion from the external environment during use, thus extending the service life of the return gas pipe 10. Stainless steel pipes also have lower manufacturing costs, which can reduce the cost of the return gas pipe 10.

[0059] Stainless steel pipes can be composed of the following components and their mass percentages: C: 0%–0.02%, Si: 0%–1%, Mn: 1%–2%, Cr: 16%–18%, Ni: 9%–11%, Cu: 2%–4%, Mo: 0%–0.03%, P: 0%–0.03%, and S: 0%–0.03%. The addition of Cu reduces the yield strength of the stainless steel pipe to 140 MPa–180 MPa, the tensile strength to 400 MPa–600 MPa, increases the elongation to 50%–80%, the yield strength ratio to less than 0.4, and the hardness to 100 Hv–120 Hv. The addition of Cr and Ni gives the stainless steel pipe a lower pitting corrosion potential, lower pitting corrosion weight loss, and a lower martensitic transformation temperature, making it more difficult for the stainless steel pipe to undergo martensitic phase transformation during processing, thus achieving stronger resistance to pitting corrosion and stress corrosion.

[0060] According to the embodiment of the present utility model, the first return pipe 101 and the second return pipe 102 are stainless steel pipes integrally formed by flexible stainless steel. The stainless steel pipe has high strength, lower yield strength and higher ductility, which can improve the reliability of the return pipe 10 during operation, and reduce the design and assembly difficulty of the HVAC device, and improve the assembly efficiency.

[0061] According to some embodiments of the present invention, the flexible stainless steel comprises at least copper and nickel, and the mass percentages of copper and nickel are as follows: Ni: 9-11% and Cu: 2-4%.

[0062] Nickel is a crucial element for stabilizing the austenitic structure, aiding in the formation and stabilization of the austenitic phase, which is fundamental to the excellent overall properties of stainless steel. The addition of nickel allows stainless steel to maintain good ductility and toughness at low temperatures. The presence of nickel helps improve the corrosion resistance of stainless steel, especially in chloride environments. Nickel can improve the cold working properties of stainless steel, making it easier to form. Nickel can enhance the high-temperature oxidation resistance and sulfidation resistance of stainless steel.

[0063] Copper can improve the corrosion resistance of stainless steel in certain environments, especially against acidic media such as sulfuric acid. The addition of copper can increase the mechanical strength of stainless steel and improve its wear resistance. Copper can form a stable protective film on the surface of stainless steel, which helps to improve its corrosion resistance. Copper has good electrical and thermal conductivity, which enhances the performance of stainless steel in these aspects. Copper also has certain antibacterial properties, which can inhibit bacterial growth to some extent.

[0064] In summary, when stainless steel contains both copper and nickel, the synergistic effect of these two elements can further improve the overall performance of stainless steel, including better corrosion resistance, higher mechanical strength, and better processing performance.

[0065] According to some embodiments of this utility model, refer to Figures 1-2 The first return air pipe 101 and / or the second return air pipe 102 include multiple straight pipes 103, with a bend 3 connecting between two adjacent straight pipes 103. Alternatively, the first return air pipe 101 may include multiple straight pipes 103, with the bend 3 connecting between two adjacent straight pipes 103; or the second return air pipe 102 may include multiple straight pipes 103, with the bend 3 connecting between two adjacent straight pipes 103; or both the first return air pipe 101 and the second return air pipe 102 may include multiple straight pipes 103, with the bend 3 connecting between two adjacent straight pipes 103.

[0066] Straight pipes 103 are provided in the first return air pipe 101 and / or the second return air pipe 102 to facilitate the connection and assembly of the first return air pipe 101 and / or the second return air pipe 102.

[0067] According to some embodiments of this utility model, refer to Figure 1 The bend 3 is an arc to prevent stress concentration. The bend 3 of the first return pipe 101 and / or the second return pipe 102 is an arc-shaped bend design, rather than a simple right angle or acute angle turn. This design helps the refrigerant flow through the bend 3, reduces refrigerant fluid resistance and turbulence, thereby reducing energy loss and improving system efficiency; the arc-shaped bend 3 can guide the refrigerant flow more naturally, reduce the impact of the refrigerant on the pipe wall of the return pipe 10, increase system stability, and may reduce wear on the pipe wall during long-term operation.

[0068] According to some embodiments of this utility model, refer to Figure 1 The first return pipe 101 includes a first pipe 1 and a second pipe 2 connected together. The first pipe 1 includes a first straight pipe 11, a second straight pipe 12 and a bent pipe 13. The bent pipe 13 is connected between the first straight pipe 11 and the second straight pipe 12. The end of the second straight pipe 12 away from the bent pipe 13 is connected to the second pipe 2.

[0069] The first pipe 1 and the second pipe 2 can be integrally formed from flexible stainless steel of the return pipe 10, which can eliminate the process of processing the first pipe 1 and the second pipe 2 on the return pipe 10, and also simplify the process of processing the first pipe 1 and the second pipe 2, and ensure the connection strength between the first pipe 1 and the second pipe 2.

[0070] The first piping 1 includes a first straight pipe 11, a second straight pipe 12, and a bent pipe 13. When the return pipe 10 is integrally formed, the first straight pipe 11, the second straight pipe 12, and the bent pipe 13 can be manufactured, eliminating the need for the bent pipe 13 to be installed between the first straight pipe 11 and the second straight pipe 12. This simplifies the manufacturing process of the first straight pipe 11, the second straight pipe 12, and the bent pipe 13, ensuring the connection strength between them. The return pipe 10 is made of stainless steel. Stainless steel has lower yield strength and higher ductility, making the return pipe 10 easier to bend and allowing for a smaller bending radius for the bent pipe 13. This also reduces the likelihood of cracking on the outside and wrinkling on the inside of the bent pipe 13.

[0071] According to some embodiments of this utility model, refer to Figure 1 A bend 3 is provided between the second pipe 2 and the first pipe 1. The second pipe 2 and the first pipe 1 are set at an angle. When the refrigerant flows in the return pipe 10, the return pipe 10 is bent to reduce the vibration of the return pipe 10.

[0072] According to some embodiments of this utility model, refer to Figure 1The diameters of the first straight pipe 11 and the second straight pipe 12 are both d, and the bending radius of the bent pipe 13 is r, satisfying 1.2d≤r≤1.5d. The first return air pipe 101 is made of stainless steel, which allows the bent pipe 13 to have a smaller bending radius; moreover, stainless steel pipes are stronger, have better resistance to vibration stress, and are less prone to vibration cracking, which can reduce the number of bent pipes 13 set in the return air pipe 10 to reduce vibration stress, thereby saving pipeline space and reducing the overall size of the machine.

[0073] For example, the diameter of the first straight pipe 11 and the second straight pipe 12 can both be 15mm, and the bending radius of the bent pipe 13 can be in the range of 18mm-22.5mm. For example, the bending radius of the bent pipe 13 can be 18mm, 19mm, 20mm, 22mm or 22.5mm, etc.

[0074] According to some embodiments of this utility model, refer to Figure 1 The second return air pipe 102 includes multiple pipe segments, with the bend 3 connecting two adjacent pipe segments. The multiple pipe segments are the first pipe segment 21, the second pipe segment 2, the third pipe segment 23, the fourth pipe segment 24, and the fifth pipe segment 25 connected in sequence.

[0075] When the refrigerant flows in the second return pipe 102, it impacts the second return pipe 102. At the same time, when the HVAC system is working, the compressor 100 will vibrate. Multiple bends 3 are formed on the second return pipe 102. The multiple bends 3 can make the second return pipe 102 better withstand the impact from the compressor 100 and the refrigerant. At the same time, the bends 3 are connected between two adjacent pipe sections, which can facilitate the flow of refrigerant in the second return pipe 102.

[0076] The first pipe section 21, the third pipe section 23, and the fifth pipe section 25 are all along the first direction (e.g., attached). Figure 1 The first and second directions are perpendicular to each other. The second pipe segment 2 and the fifth pipe segment 25 extend in the second direction (e.g., horizontal direction).

[0077] Based on the spatial layout of the HVAC system, the bend 3 of the second return air pipe 102 and the extension direction of multiple pipe sections are designed to rationally arrange the spatial position of the second return air pipe 10, so that the second return air pipe 10 can better withstand the impact from the refrigerant and the vibration of the compressor 100, referring to... Figure 1 This improves the reliability of the second return air pipe 10 during operation.

[0078] According to some embodiments of the present invention, an expansion tube is provided at one end of the first return air pipe 101 and / or the second return air pipe 102, the diameter of which is larger than the diameter of the straight pipe 103; and a retraction tube is provided at the other end of the first return air pipe 101 and / or the second return air pipe 102, the diameter of which is smaller than the diameter of the straight pipe 103; or, an expansion tube is provided at both ends of the first return air pipe 101 and / or the second return air pipe 102, the diameter of which is larger than the diameter of the straight pipe 103; or, a retraction tube is provided at both ends of the first return air pipe 101 and / or the second return air pipe 102, the diameter of which is smaller than the diameter of the first straight pipe 103.

[0079] The external piping 6 can extend into the expansion tube, and one end of the external piping 6 can abut against the bottom wall of the expansion tube. This restricts the installation position of the external piping 6 with the first return gas pipe 101 and / or the second return gas pipe 102, facilitating connection between one end of the external piping 6 and the first return gas pipe 101 and / or the second return gas pipe 102. The external piping 6 can extend into the expansion tube and can be fixed to the expansion tube by welding. Stainless steel pipes have lower yield strength, lower hardness, and higher ductility, thus making the processing of the expansion tube easier and allowing for a higher flaring ratio.

[0080] The retraction tube can extend into the external piping 6, and one end of the retraction tube can abut against the bottom wall of the external piping 6 to restrict the installation position of the external piping 6 and the first return air pipe 101 and / or the second return air pipe 102, facilitating the connection between one end of the external piping 6 and the first return air pipe 101 and / or the second return air pipe 102. The retraction tube can extend into the external piping 6, and the external piping 6 and the expansion tube can be fixed by welding. Stainless steel pipes have lower yield strength, lower hardness, and higher ductility, therefore the retraction tube is easier to process and allows for a higher necking rate.

[0081] According to some embodiments of this utility model, the expansion tube includes at least one sub-expansion tube. The expansion tube may include one sub-expansion tube or multiple sub-expansion tubes. When there are multiple sub-expansion tubes, they are connected sequentially. In the direction from the bend 3 to the straight pipe 103, the diameters of the multiple sub-expansion tubes increase sequentially. The diameter of the sub-expansion tube closer to the bend 3 is smaller than the diameter of the sub-expansion tube farther from the bend 3, causing the sub-expansion tubes to expand outwards sequentially. The external piping 6 can also retract correspondingly to the multiple sub-expansion tubes, allowing for better positioning of the external piping 6 and the straight pipe 103.

[0082] According to some embodiments of this utility model, the retraction tube includes at least one sub-retraction tube. It can be that the retraction tube includes one sub-retraction tube, or it can include multiple sub-retraction tubes. When there are multiple sub-retraction tubes, they are connected sequentially. In the direction from the bend 3 to the straight pipe 103, the diameters of the multiple sub-retraction tubes decrease sequentially. The diameter of the sub-retraction tube closer to the bend 3 is larger than the diameter of the sub-retraction tube farther from the bend 3, causing the sub-retraction tubes to retract inward sequentially. The external piping 6 can also expand correspondingly to the multiple sub-retraction tubes, allowing for better positioning of the external piping 6 and the straight pipe 103.

[0083] According to some embodiments of this utility model, a limiting portion is provided at one end of the first return air pipe 101 and / or the second return air pipe 102. The limiting portion cooperates with the external piping 6 to limit the depth to which the first return air pipe 101 and / or the second return air pipe 102 is inserted into the external piping 6, and to position the installation position between the first return air pipe 101 and / or the second return air pipe 102 and the external piping 6. For example, the limiting portion can be a protrusion on the outer wall of the straight pipe 103. When the straight pipe 103 is inserted into the external piping 6, the protrusion can abut against the axial end face of the external piping 6.

[0084] According to some embodiments of this utility model, the limiting part is a protrusion. The protrusion can be disposed on the outer wall of the straight pipe 103, or it can be integrally formed on the straight pipe 103, which simplifies the processing technology of the protrusion. When the external pipe 6 is inserted into the straight pipe 103, the protrusion can abut against the axial end face of the external pipe 6 to limit the installation position between the straight pipe 103 and the external pipe 6. Multiple protrusions can be provided, and the multiple protrusions can be spaced apart along the circumference of the straight pipe 103.

[0085] Alternatively, the limiting part can be an annular protrusion extending around the axis of the straight pipe 103. The annular protrusion can be provided on the outer wall of the straight pipe 103; or the annular protrusion can be integrally formed on the straight pipe 103, which simplifies the processing technology of the annular protrusion. When the external piping 6 is inserted into the straight pipe 103, the annular protrusion can abut against the axial end face of the external piping 6 to limit the installation position between the straight pipe 103 and the external piping 6.

[0086] According to some embodiments of this utility model, refer to Figures 1-13 The yield strength of flexible stainless steel is 140–180 MPa; and / or, the tensile strength of flexible stainless steel is reduced to 400–600 MPa; and / or, the elongation of flexible stainless steel is 50–80%; and / or, the yield strength ratio of flexible stainless steel is less than 0.4; and / or, the hardness of flexible stainless steel material is 100–120 Hv.

[0087] For example, the yield strength of flexible stainless steel can be 140MPa, 150MPa, 160MPa, 170MPa or 180MPa, etc.; the tensile strength of flexible stainless steel can be 400MPa, 450MPa, 500MPa, 550MPa or 600MPa, etc.; the elongation of flexible stainless steel can be 50%, 60%, 70% or 80%, etc.; the hardness of flexible stainless steel can be 100Hv, 110Hv, 115Hv or 120Hv, etc.

[0088] According to some embodiments of this utility model, refer to Figures 1-13 Flexible stainless steel is composed of the following components by weight percentage: C: less than 0.02%, Si: 0.5%–1%, Mn: 1–2%, Cr: 16–18%, Ni: 9–11%, Cu: 2–4%, Mo: 0–0.02%, P: less than 0.03%, S: less than 0.03%, with the remainder consisting of Fe and unavoidable impurities. The addition of Cu reduces the yield strength of the flexible stainless steel to 140–180 MPa, the tensile strength to 400–600 MPa, increases the elongation to 50%–80%, the yield strength ratio to less than 0.4, and the hardness to 100 Hv–120 Hv. The addition of Cr and Ni gives the flexible stainless steel a lower pitting corrosion potential, lower pitting corrosion weight loss, and lower martensitic transformation temperature, making it more difficult for the flexible stainless steel to undergo martensitic phase transformation during processing, thus achieving stronger resistance to pitting corrosion and stress corrosion.

[0089] It should be further explained that the flexible stainless steel material involved in this utility model has a lower C element content, which makes it more difficult for it to pass through the material sensitization range during hot working and welding, effectively controlling the formation of M23C6, thereby achieving stronger resistance to intergranular corrosion and effectively reducing welding defects.

[0090] According to some embodiments of this utility model, refer to Figures 1-13The Md30 of flexible stainless steel ranges from -50℃ to -80℃. For example, the Md30 of flexible stainless steel can be -50℃, 60℃, 70℃, or 80℃. In the field of flexible stainless steel materials, "Md30" refers to the critical temperature for martensitic transformation. Specifically, "Md30" is the temperature at which 50% martensite is formed with 30% deformation. This parameter is very important for predicting the behavior of flexible stainless steel during processing because the formation of martensite affects the hardness and magnetism of the material. Generally speaking, the lower the "Md30" value, the more difficult it is for the material to form martensite under the same deformation conditions. Therefore, the material has stronger resistance to aging cracking, i.e., it is less prone to cracking. Conversely, if the "Md30" value is high, the material is more likely to form martensite during processing, which may lead to cracking. Therefore, by ensuring that the critical temperature for martensitic transformation of flexible stainless steel meets the above conditions, the refrigerant transport module 100 can operate well in low-temperature environments with good stability.

[0091] According to some embodiments of this utility model, refer to Figures 1-13 Flexible stainless steel is an austenitic stainless steel with an average grain size of 20μm to 40μm. For example, the specific average grain size of flexible stainless steel can be 20μm, 25μm, 30μm, 35μm, or 40μm. Therefore, austenitic stainless steel with a grain size of 20μm to 40μm not only maintains the inherent good corrosion resistance and processability of austenitic stainless steel, but also achieves superior mechanical properties and a potentially longer service life due to its refined grain size.

[0092] According to some embodiments of this utility model, refer to Figures 1-13 Stainless steel pipes have a wall thickness of 1.2mm to 1.5mm. Stainless steel pipes have high strength, strong chemical stability, and low yield strength, allowing for thinner pipe walls. For example, the wall thickness of stainless steel pipes can be 1.2mm, 1.3mm, 1.4mm, or 1.5mm, etc.

[0093] According to some embodiments of this utility model, refer to Figures 1-13One or both ends of the first return gas pipe 101 and / or the second return gas pipe 102 are connected to an external piping 6. The first return gas pipe 101, the second return gas pipe 102, and the external piping 6 are all integrally formed flexible stainless steel pipes. The first return gas pipe 101 and the external piping 6, and the second return gas pipe 102 and the external piping 6 are welded together by a first solder 51, wherein the first solder 51 contains, by weight, Cu: 46%–50%, Ni: 9%– 11%, Si: 0.04%~0.25%, the remainder is composed of Zn and unavoidable impurities; the flux used when using the first solder 51 contains 60%-80% boric acid, 5%-15% fluoride, and 10%-20% potassium borate, calculated by Wt%; the melting temperature t1 when using the first solder 51 satisfies: 910℃≤t1≤935℃; the brazing temperature t2 when using the first solder 51 satisfies: 950℃≤t2≤975℃.

[0094] Specifically, for brazing, flame welding or high-frequency welding technology can be selected, which results in a wider welding activity range, less post-weld residue, stronger corrosion resistance and better reliability at the weld, and a significant reduction in welding costs; the welding temperature requirement is low, making it less likely to burn the base material; the solder has good fluidity and filling properties, allowing for more relaxed requirements on pipe diameter and fitting clearance, high stability and strong reliability; and it does not require an ammonia decomposition furnace, thus requiring lower processing precision.

[0095] The return pipe and external piping 6 can be welded using brazing or fusion welding techniques with the first solder 51 and flux. For brazing, flame welding or high-frequency welding techniques can be selected, and flux is used, which has a wider activity range and less residue after welding. For fusion welding, argon arc welding techniques can be selected, with the weld position 0cm to 2cm from the interface, the weld width 2mm to 10mm, and the weld strength not less than 80% of the base material. It has more relaxed requirements on the weld position and the size of the weld area.

[0096] According to some embodiments of this utility model, refer to Figures 1-13 One or both ends of the first return pipe 101 and / or the second return pipe 102 are connected to an external pipe 6. The first return pipe 101 and the second return pipe 102 are both integrally formed stainless steel pipes made of flexible stainless steel. The external pipe 6 is a copper pipe or a copper alloy pipe. The first return pipe 101 and the external pipe 6, and the second return pipe 102 and the external pipe 6 are welded together by a second solder 52.

[0097] The second solder 52 contains, by weight (wt%), Cu: 57%-61%, Sn: 1.0%-1.5%, Si: 0.05%-0.2%, with the remainder consisting of Zn and unavoidable impurities; the flux used when using the second solder 52 contains, by weight (wt%), 60%-80% boric acid, 5%-15% fluoride, and 10%-20% potassium borate; the melting temperature t3 when using the second solder 52 satisfies: 880℃≤t1≤890℃; the brazing temperature t4 when using the second solder 52 satisfies: 920℃≤t2≤930℃.

[0098] It is understandable that when the materials of the first pipe 1 and the external pipe 6 are different, the solder required for welding the first pipe 1 and the external pipe 6 will also be different.

[0099] Flexible stainless steel is a type of stainless steel material with high ductility and flexibility. It can adapt to complex shape changes and bending requirements without losing its corrosion resistance and mechanical strength. Even after a complex forming process, it can still maintain good mechanical strength and compressive strength. Flexible stainless steel is easy to process by bending, welding and connecting.

[0100] According to some embodiments of this utility model, refer to Figures 1-13 One or both ends of the first return pipe 101 and / or the second return pipe 102 are connected to an external pipe 6. One or both ends of the first return pipe 101 and / or the second return pipe 102 are provided with a first sleeve 41. The end of the external pipe 6 near the first pipe 1 is provided with a second sleeve 42. The first sleeve 41 and the second sleeve 42 are welded together by a third solder 53 or a fourth solder 54. The first sleeve 41 and the second sleeve 42 are both copper pipes or copper alloy pipes; the third solder 53 is tin bronze solder; and the fourth solder 54 is silver copper solder.

[0101] According to some embodiments of this utility model, refer to Figures 1-13 A first sleeve 41 is welded to one end of the first return air pipe 101 and the second return air pipe 102. A second sleeve 42 is provided at the end of the external piping 6 near the first return air pipe 101 or the second return air pipe 102. The first sleeve 41 and the second sleeve 42 are copper pipes or copper alloy pipes. Through the bridging effect of the first sleeve 41 and the second sleeve 42, and by adjusting the model of the first sleeve 41 and the second sleeve 42 of the external piping 6, the connection between the first return air pipe 101 or the second return air pipe 102 and different models of the external piping 6 can be realized, thereby reducing the difficulty of product design. When the return air pipe 10 is assembled into the equipment, the external piping 6 is connected to the components on the equipment. During the product design process, the size or shape of the external piping 6 can be adjusted, so that the return air pipe 10 can be adapted to more models of equipment.

[0102] In a specific example, when welding the return gas pipe 10 to the external piping 6, if the external piping 6 is also made of stainless steel, the return gas pipe 10 and the external piping 6 are directly welded. The welding of the return gas pipe 10 to the external piping 6 is performed using brazing or fusion welding techniques with solder and flux. For brazing, flame welding or high-frequency welding techniques can be selected, using flux, which has a wider activity range and less residue after welding. For fusion welding, argon arc welding can be selected, with the weld position 0cm to 2cm from the interface, the weld width 2mm to 10mm, and the weld strength not less than 80% of the base material. It has more relaxed requirements on the weld position and the size of the weld area.

[0103] For example, the composition and mass percentage of the solder for welding stainless steel pipes are as follows: Cu: 46%-50%, Ni: 9%-11%, Si: 0.04%-0.25%, with the remainder being Zn; melting temperature range: 910℃-935℃; recommended brazing temperature: 950℃-975℃. The composition and mass percentage of the flux are as follows: boric acid: 60%-80%, fluoride: 5%-15%, potassium borate: 10%-20%.

[0104] The HVAC device according to the second aspect of the present invention includes: a compressor 100, a gas-liquid separator 200 and a four-way valve assembly 300. The return pipe 10 according to the first aspect of the present invention includes a first return pipe 101 and a second return pipe 102. One end of the first return pipe 101 is connected between the compressor 100 and the gas-liquid separator 200, and the second return pipe 102 is connected between the gas-liquid separator 200 and the four-way valve assembly 300.

[0105] The refrigerant is delivered to the second return pipe 102 via the four-way valve assembly 300, then reaches the gas-liquid separator 200 via the second return pipe 102, and after separation in the gas-liquid separator 200, it reaches the compressor 100 via the first return pipe 101. According to this embodiment of the HVAC system, by setting the aforementioned return pipe 10, the effectiveness of the HVAC system can be improved, and the reliability of the HVAC system during operation can be increased. Furthermore, the difficulty in the production and design process of the HVAC system can be reduced, and production efficiency can be improved.

[0106] The following reference Figures 1-13 This invention describes a return air pipe 10 and a heating and ventilation device having the same according to an embodiment of the present invention.

[0107] The HVAC system includes a compressor 100, a gas-liquid separator 200, and a four-way valve assembly 300.

[0108] The return pipe 10 includes a first return pipe 101 and a second return pipe 102. One end of the first return pipe 101 is connected between the compressor 100 and the gas-liquid separator 200, and the second return pipe 102 is connected between the gas-liquid separator 200 and the four-way valve assembly 300.

[0109] Both the first return air pipe 101 and the second return air pipe 102 are integrally formed flexible stainless steel pipes. Both the first return air pipe 101 and the second return air pipe 102 have multiple bends 3. The first return air pipe 101 includes a first conduit 1 and a second conduit 2 connected together. The first conduit 1 includes a first straight pipe 11, a second straight pipe 12, and a bend 13. The bend 13 connects the first straight pipe 11 and the second straight pipe 12. The end of the second straight pipe 12 furthest from the bend 13 is connected to the second conduit 2. The diameter of both the first straight pipe 11 and the second straight pipe 12 is 15mm, and the bending radius of the bend 13 can be in the range of 18mm-22.5mm.

[0110] An expansion tube or a retraction tube is provided at one end of the first return air pipe 101 and / or the second return air pipe 102. The diameter of the expansion tube is larger than the diameter of the straight pipe 103, and the diameter of the retraction tube is smaller than the diameter of the straight pipe 103. The expansion tube includes multiple sub-expansion tubes connected in sequence, and the diameters of the multiple sub-expansion tubes increase sequentially in the direction from the bend 3 to the straight pipe 103. The retraction tube includes multiple sub-retraction tubes connected in sequence, and the diameters of the multiple sub-retraction tubes decrease sequentially in the direction from the bend 3 to the straight pipe 103.

[0111] A limiting part is provided at the end of the straight pipe 103 away from the bend 13. The limiting part is a convex hull or an annular protrusion extending around the axis of the straight pipe 103. The convex hull or annular protrusion is used to limit the depth of the straight pipe 103 inserted into the external piping 6 and to position the installation position between the external piping 6 and the straight pipe 103.

[0112] The second return air pipe 102 includes multiple pipe segments, with a bend 3 connecting adjacent pipe segments. These multiple pipe segments are, in sequence, a first pipe segment 21, a second pipe segment 2, a third pipe segment 23, a fourth pipe segment 24, and a fifth pipe segment 25. The first pipe segment 21, the third pipe segment 23, and the fifth pipe segment 25 are all along a first direction (e.g., attached). Figure 1 The first and second directions are perpendicular to each other. The second return pipe 102 is bent so that it can withstand higher intensity impacts from the compressor 100 and refrigerant, thereby improving the reliability of the return pipe 10 during operation.

[0113] In the description of this specification, references to terms such as "some embodiments," "optionally," "furthermore," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0114] Although embodiments of the present invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A return air pipe, characterized in that, The return gas pipe includes a first return gas pipe and a second return gas pipe. The first return gas pipe is connected between the compressor and the gas-liquid separator, and the second return gas pipe is connected between the gas-liquid separator and the four-way valve assembly. The first return gas pipe and / or the second return gas pipe have multiple bends. The first return gas pipe and / or the second return gas pipe are integrally formed flexible stainless steel pipes. The bends are used to guide the refrigerant flow and reduce the impact of the refrigerant on the pipe wall. The first return pipe includes a first piping and a second piping connected together. The first piping includes a first straight pipe, a second straight pipe and a bend pipe. The bend pipe is connected between the first straight pipe and the second straight pipe. The end of the second straight pipe away from the bend pipe is connected to the second piping. The diameters of the first straight pipe and the second straight pipe are both d, and the bending radius of the bent pipe is r, satisfying 1.2d≤r≤1.5d.

2. The return air pipe according to claim 1, characterized in that, The first return air pipe and / or the second return air pipe includes a plurality of straight pipes, and the bend is connected between two adjacent straight pipes.

3. The return air pipe according to claim 1, characterized in that, The bent portion is an arc.

4. The return air pipe according to claim 1, characterized in that, The bending section is provided between the second pipe and the first pipe.

5. The return air pipe according to claim 1, characterized in that, The second return air pipe includes multiple pipe segments, and the bend is connected between two adjacent pipe segments. The multiple pipe segments are a first pipe segment, a second pipe segment, a third pipe segment, a fourth pipe segment, and a fifth pipe segment connected in sequence. The first pipe segment, the third pipe segment, and the fifth pipe segment all extend along a first direction, and the second pipe segment and the fifth pipe segment extend along a second direction. The first direction and the second direction are perpendicular to each other.

6. The return air pipe according to claim 2, characterized in that, An expansion tube is provided at one end of the first return air pipe and / or the second return air pipe, the diameter of which is larger than the diameter of the straight pipe; a retraction tube is provided at the other end of the first return air pipe and / or the second return air pipe, the diameter of which is smaller than the diameter of the straight pipe; or, expansion tubes are provided at both ends of the first return air pipe and / or the second return air pipe, the diameter of which is larger than the diameter of the straight pipe; or, retraction tubes are provided at both ends of the first return air pipe and / or the second return air pipe, the diameter of which is smaller than the diameter of the straight pipe.

7. The return air pipe according to claim 6, characterized in that, The expansion tube includes at least one sub-expansion tube. When there are multiple sub-expansion tubes, the multiple sub-expansion tubes are connected in sequence, and the diameters of the multiple sub-expansion tubes increase in sequence in the direction from the bend to the straight tube; and / or, the retraction tube includes at least one sub-retraction tube. When there are multiple sub-retraction tubes, the multiple sub-retraction tubes are connected in sequence, and the diameters of the multiple sub-retraction tubes decrease in sequence in the direction from the bend to the straight tube.

8. The return air pipe according to claim 7, characterized in that, The first return pipe and / or the second return pipe have a limiting part at one end that cooperates with the external piping; or, the first return pipe and / or the second return pipe have limiting parts at both ends that cooperate with the external piping.

9. The return air pipe according to claim 8, characterized in that, The limiting part is a convex hull or an annular protrusion extending around the axis of the straight tube.

10. The return pipe according to any one of claims 1-9, characterized in that, The yield strength of the flexible stainless steel is 140~180MPa; and / or, the tensile strength of the flexible stainless steel is reduced to 400~600MPa; and / or, the elongation of the flexible stainless steel is 50~80%; and / or, the yield strength ratio of the flexible stainless steel is less than 0.4; and / or, the hardness of the flexible stainless steel material is 100~120Hv.

11. The return pipe according to any one of claims 1-9, characterized in that, The Md30 of the flexible stainless steel is -50℃ to -80℃.

12. The return pipe according to any one of claims 1-9, characterized in that, The flexible stainless steel is austenitic stainless steel, and the average grain size of the stainless steel is 20μm~40μm.

13. The return pipe according to any one of claims 1-9, characterized in that, The wall thickness of stainless steel pipes is 1.2mm to 1.5mm.

14. The return pipe according to any one of claims 1-9, characterized in that, One or both ends of the first or second return pipe are connected to external piping. The first return pipe, the second return pipe, and the external piping are all integrally formed stainless steel pipes made of flexible stainless steel.

15. The return pipe according to any one of claims 1-9, characterized in that, One or both ends of the first or second return gas pipe are connected to external piping. The first and second return gas pipes are integrally formed stainless steel pipes made of flexible stainless steel, and the external piping is a copper pipe or a copper alloy pipe.

16. The return pipe according to any one of claims 1-9, characterized in that, One or both ends of the first or second return gas pipe are connected to an external pipe. One or both ends of the first or second return gas pipe are provided with a first sleeve, and one or both ends of the first or second return gas pipe are provided with a second sleeve. The first sleeve and the second sleeve are both copper pipes or copper alloy pipes.

17. An air conditioner, characterized in that, include: A compressor, a gas-liquid separator, and a four-way valve assembly, wherein the return pipe of any one of claims 1-16 comprises a first return pipe and a second return pipe, the first return pipe being connected between the compressor and the gas-liquid separator, and the second return pipe being connected between the gas-liquid separator and the four-way valve assembly.

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