Valve units and HVAC systems containing them

Abstract

This utility model discloses a valve unit and a heating and ventilation device having the same. The valve unit includes a main pipe and at least one first valve connector. The first valve connector includes a first connecting pipe and a second connecting pipe. The first connecting pipe is located between the main pipe and the second connecting pipe. The second connecting pipe is connected to an external piping. The second connecting pipe is a bent pipe. The first and second connecting pipes are integrally formed flexible stainless steel pipes. According to the valve unit of this utility model embodiment, by making the first and second connecting pipes integrally formed flexible stainless steel components, the welding process between the first and second connecting pipes can be reduced. The connection strength and sealing performance between the first and second connecting pipes can also be improved. Furthermore, flexible stainless steel is less expensive than copper, thereby reducing the production cost of the valve unit.

Description

Technical Field

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

[0002] In related technologies, control valves, such as check valves and four-way valves, are often installed in HVAC systems. Taking the four-way valve as an example, it has many connection points, and the connection is often welded. As a result, the assembly is more complicated and the welding cost is higher. In addition, the four-way valve has high requirements for the structural strength and sealing performance after welding. Utility Model Content

[0003] The present invention aims to solve at least one of the technical problems existing in the prior art. Therefore, one objective of the present invention is to provide a valve unit that is simple to assemble, has low welding costs, and exhibits good structural strength and sealing performance.

[0004] According to an embodiment of the present invention, the valve unit includes: a main body pipe; at least one first valve connector, the first valve connector including a first connecting pipe and a second connecting pipe, the first connecting pipe being located between the main body pipe and the second connecting pipe, the second connecting pipe being connected to an external piping, wherein the second connecting pipe is a bent pipe, and the first connecting pipe and the second connecting pipe are integrally formed stainless steel pipes of flexible stainless steel.

[0005] According to the valve unit of this utility model embodiment, by making the first connecting pipe and the second connecting pipe an integral part of flexible stainless steel, the welding process between the first connecting pipe and the second connecting pipe can be reduced, and the connection strength and sealing performance between the first connecting pipe and the second connecting pipe can be improved. Furthermore, flexible stainless steel is less expensive than copper, thereby reducing the production cost of the valve unit.

[0006] In addition, the valve unit according to this utility model also has the following additional technical features:

[0007] In some embodiments of this utility model, the main tube is a stainless steel tube integrally formed from flexible stainless steel.

[0008] In some embodiments of this utility model, the main tube and the first valve tube are integrally formed stainless steel parts made of flexible stainless steel.

[0009] In some embodiments of this utility model, the first connecting pipe is a straight pipe.

[0010] In some embodiments of this utility model, the valve unit further includes at least one second valve connector, the second valve connector including a third connecting pipe and a fourth connecting pipe, the third connecting pipe being located between the main body pipe and the fourth connecting pipe, the fourth connecting pipe being connected to an external piping, wherein the fourth connecting pipe is a straight pipe, and the third connecting pipe and the fourth connecting pipe are integrally formed stainless steel pipes of the flexible stainless steel.

[0011] In some embodiments of this utility model, the third connecting pipe is a straight pipe.

[0012] In some embodiments of this utility model, the end of the second connecting pipe away from the first connecting pipe is provided with a first retractable portion, the outer diameter of the first retractable portion being smaller than the outer diameter of the first connecting pipe; or, the end of the second connecting pipe away from the first connecting pipe is provided with a first expanding portion, the outer diameter of the first expanding portion being larger than the outer diameter of the first connecting pipe; and / or, the end of the fourth connecting pipe away from the third connecting pipe is provided with a second retractable portion, the outer diameter of the second retractable portion being smaller than the outer diameter of the third connecting pipe; or, the end of the fourth connecting pipe away from the third connecting pipe is provided with a second expanding portion, the outer diameter of the second expanding portion being larger than the outer diameter of the third connecting pipe.

[0013] In some embodiments of this utility model, in the direction from the first connecting pipe to the second connecting pipe, the outer diameter of the first retracted portion gradually decreases, or the outer diameter of the first expanded portion gradually increases; and / or, in the direction from the third connecting pipe to the fourth connecting pipe, the outer diameter of the second retracted portion gradually decreases, or the outer diameter of the second expanded portion gradually increases.

[0014] In some embodiments of this utility model, the valve unit is a four-way valve, and the valve unit includes a first valve pipe, a second valve pipe, a third valve pipe, and a fourth valve pipe, wherein at least one of the first valve pipe, the second valve pipe, the third valve pipe, and the fourth valve pipe is the first valve connector; or at least one of the first valve pipe, the second valve pipe, the third valve pipe, and the fourth valve pipe is the second valve connector; or a portion of the first valve pipe, the second valve pipe, the third valve pipe, and the fourth valve pipe is the first valve connector, and the remainder is the second valve connector.

[0015] In some embodiments of this utility model, the second connecting pipe includes a first straight pipe section, a bent section, and a second straight pipe section connected in sequence. The first straight pipe section and the second straight pipe section are arranged in parallel. The bending radius of the bent section is r. The outer diameter d of the first straight pipe section or the second straight pipe section satisfies: 1.2d≤r≤1.5d.

[0016] In some embodiments of this utility model, 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.

[0017] In some embodiments of this utility model, the flexible stainless steel is composed of the following components by weight percentage: C: less than 0.02%, Si: 0.5% to 1%, Mn: 1 to 2%, Cr: 16 to 18%, Ni: 9 to 11%, Cu: 2 to 4%, Mo: 0 to 0.02%, P: less than 0.03%, S: less than 0.03%, with the remainder consisting of Fe and unavoidable impurities.

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

[0019] In some embodiments of this utility model, the flexible stainless steel is austenitic stainless steel, and the average grain size of the flexible stainless steel is 20μm to 40μm.

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

[0021] This utility model also proposes a heating and ventilation device.

[0022] According to the HVAC device of the present invention, by providing the valve unit of the above embodiment, the welding process between the first connecting pipe and the second connecting pipe can be reduced, and the connection strength and sealing performance between the first connecting pipe and the second connecting pipe can be improved. Furthermore, flexible stainless steel is less expensive than copper, thereby reducing the production cost of the valve unit.

[0023] In some embodiments of this utility model, the valve unit is a four-way valve, comprising a first valve pipe, a second valve pipe, a third valve pipe, and a fourth valve pipe. The HVAC system further includes a compressor, a high-pressure side outlet pipe, and a low-pressure side outlet pipe. The first valve pipe is connected to the compressor's exhaust pipe, the second valve pipe is connected to the compressor's suction pipe, the third valve pipe is connected to the high-pressure side outlet pipe, and the fourth valve pipe is connected to the low-pressure side outlet pipe.

[0024] At least one of the first valve tube, the second valve tube, the third valve tube, and the fourth valve tube is the first valve tube.

[0025] In some embodiments of this utility model, the exhaust pipe and the first valve pipe are both integrally formed flexible stainless steel pipes, and the exhaust pipe and the first valve pipe are welded together by a first solder; and / or, the intake pipe and the second valve pipe are both integrally formed flexible stainless steel pipes, and the intake pipe and the second valve pipe are welded together by a first solder; and / or, the high-pressure side outlet pipe and the third valve pipe are both integrally formed flexible stainless steel pipes, and the intake pipe and the third valve pipe are welded together by a first solder; and / or, the low-pressure side outlet pipe and the fourth valve pipe are both integrally formed flexible stainless steel pipes. The steel pipe, the low-pressure side outlet pipe and the fourth valve pipe are welded together by a first solder, wherein the first solder contains, by weight (wt%), Cu: 46%–50%, Ni: 9%–11%, Si: 0.04%–0.25%, with the remainder consisting of Zn and unavoidable impurities; the flux used when using the first solder contains, by weight (wt%), 60%–80% boric acid, 5%–15% fluoride, and 10%–20% potassium borate; the melting temperature t1 when using the first solder satisfies: 910℃ ≤ t1 ≤ 935℃; the brazing temperature t2 when using the first solder satisfies: 950℃ ≤ t2 ≤ 975℃.

[0026] In some embodiments of this utility model, one of the exhaust pipe and the first valve pipe is a flexible stainless steel pipe integrally formed, and the other is a copper pipe or a copper alloy pipe, and the exhaust pipe and the first valve pipe are welded together by a second solder; and / or, one of the intake pipe and the second valve pipe is a flexible stainless steel pipe integrally formed, and the other is a copper pipe or a copper alloy pipe, and the intake pipe and the second valve pipe are welded together by a second solder; and / or, one of the high-pressure side outlet pipe and the third valve pipe is a flexible stainless steel pipe integrally formed, and the other is a copper pipe or a copper alloy pipe, and the high-pressure side outlet pipe and the third valve pipe are welded together by a second solder; and / or, the low-pressure side outlet pipe and the first valve pipe are... One of the four valves is a flexible stainless steel tube integrally formed, and the other is a copper tube or copper alloy tube. The low-pressure side outlet tube and the fourth valve tube are welded together by a second solder, wherein the second solder contains, by weight, 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 contains, by weight, 60%-80% boric acid, 5%-15% fluoride, and 10%-20% potassium borate; the melting temperature t1 when using the second solder satisfies: 880℃≤t1≤890℃; the brazing temperature t2 when using the second solder satisfies: 920℃≤t2≤930℃.

[0027] 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

[0028] 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:

[0029] Figure 1 This is a structural schematic diagram of a compressor assembly according to an embodiment of the present utility model.

[0030] Figure 2 This is a structural schematic diagram of the four-way valve assembly and the gas-liquid separator according to an embodiment of the present utility model.

[0031] Figure 3 This is a structural schematic diagram of a four-way valve assembly according to an embodiment of the present utility model.

[0032] Figure 4 This is a schematic diagram of the bent tube structure of the four-way valve assembly according to an embodiment of the present utility model.

[0033] Figure 5 This is a structural schematic diagram of the exhaust pipe, compressor, and four-way valve of the compressor assembly according to an embodiment of the present utility model.

[0034] Figure 6 This is a schematic diagram of the structure of a four-way valve according to an embodiment of the present utility model.

[0035] Figure 7 This is a system diagram of the HVAC device according to an embodiment of the present utility model, and a structural schematic diagram of the compressor assembly.

[0036] Figure 8 This is a schematic diagram of the structure of the four-way valve and the outdoor heat exchanger of the heating and ventilation device according to an embodiment of the present utility model.

[0037] Figure 9 This is a schematic diagram of the structure of the four-way valve and compressor of the HVAC device according to an embodiment of the present utility model.

[0038] Figure 10 This is a schematic diagram of the structure of the four-way valve, compressor, and gas-liquid separator of the HVAC device according to an embodiment of the present utility model.

[0039] Figure 11 This is a structural schematic diagram of the four-way valve and the shut-off valve of the HVAC device according to an embodiment of the present utility model.

[0040] Figure 12 This is a welding diagram of the fifth and sixth welded pipes according to an embodiment of the present utility model.

[0041] Figure 13 This is a schematic diagram of the welding between the first welded pipe and the second welded pipe according to an embodiment of the present utility model.

[0042] Figure 14 This is a welding diagram of the third and fourth welded pipes according to an embodiment of the present utility model.

[0043] Figure 15 yes Figure 12 A magnified view of region A in the middle.

[0044] Figure 16 yes Figure 13 A magnified view of region B in the middle.

[0045] Figure 17 yes Figure 14 A magnified view of region C in the middle.

[0046] Figure 18 This is a system diagram of a heating, ventilation, and air conditioning (HVAC) device according to an embodiment of the present utility model.

[0047] Figure label:

[0048] 10. Four-way valve;

[0049] 1. Main pipe;

[0050] 2. First valve connector; 201. First connecting pipe; 202. Second connecting pipe;

[0051] 2', Second valve connector; 201', Third connecting pipe; 202', Fourth connecting pipe;

[0052] 21. First valve tube; 22. Second valve tube; 23. Third valve tube; 24. Fourth valve tube;

[0053] 3. Bent pipe; 301. First straight pipe section; 302. Second straight pipe section; 303. Bent section;

[0054] 4. Straight pipe; 51. Retraction section; 52. Expansion section;

[0055] 100. Four-way valve assembly;

[0056] 10. Four-way valve; 20. Gate valve; 30. First pipe structure;

[0057] 61. Filter; 62. First piping; 63. Second piping;

[0058] 1000, Compressor assembly;

[0059] 200, Compressor; 300, Exhaust pipe; 400, Suction pipe; 500, Gas-liquid separator; 600, Second outlet pipe; 700, First outlet pipe; 800, Oil separator;

[0060] 71. First exhaust straight pipe; 72. Second exhaust straight pipe; 73. Third exhaust straight pipe; 74. Fourth exhaust straight pipe; 75. Fifth exhaust straight pipe; 76. Sixth exhaust straight pipe;

[0061] 81. First welded pipe; 82. Second welded pipe; 83. Third welded pipe; 84. Fourth welded pipe; 85. Fifth welded pipe; 86. Sixth welded pipe; 87. First sleeve; 88. Second sleeve;

[0062] 91. First solder; 92. Second solder; 93. Third solder; 94. Fourth solder;

[0063] 2000, Indoor heat exchanger; 3000, Outdoor heat exchanger;

[0064] 4000, indoor unit; 5000, outdoor unit. Detailed Implementation

[0065] 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.

[0066] 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.

[0067] 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.

[0068] The following is for reference. Figures 1-11 A valve unit according to an embodiment of the present invention is described.

[0069] like Figures 1-11 As shown, the valve unit according to an embodiment of the present invention includes a main body pipe 1 and a first valve connector 2. The first valve connector 2 is provided with at least one component, including a first connecting pipe 201 and a second connecting pipe 202. The first connecting pipe 201 is located between the main body pipe 1 and the second connecting pipe 202, and the second connecting pipe 202 is connected to an external piping. The second connecting pipe 202 is a bent pipe, and the first connecting pipe 201 and the second connecting pipe 202 are integrally formed stainless steel pipes. The stainless steel component includes at least copper.

[0070] There can be at least one first valve connector 2, that is, there can be one first valve connector 2, such as a check valve. There can also be two first valve connector 2, that is, two-way valves. There can also be three first valve connector 2, such as three-way valves. There can also be four first valve connector 2, such as four-way valve 10. It can be understood that there can also be five or more first valve connector 2. This application does not limit this.

[0071] For the bent pipe 3, it is understandable that the space inside the housing of the HVAC system is limited. By setting the bent pipe 3, the components of the HVAC system can be arranged flexibly, which is very flexible. Furthermore, HVAC systems are prone to vibration during operation. Appropriate bending of the pipe can act as a buffer, reduce vibration transmission, thereby protecting the pipe and extending the service life of the HVAC system. Furthermore, reasonable bending of the bent pipe 3 can also help regulate the flow rate and direction of the refrigerant, optimize the refrigerant distribution in the air conditioning system, improve the heat exchange rate, and thus improve the cooling or heating performance of the HVAC system.

[0072] Furthermore, the first connecting pipe 201 and the second connecting pipe 202 are integrally formed stainless steel pipes. That is, the first connecting pipe 201 and the bent pipe 3 connected to the bent pipe 3 are integrally formed components made of flexible stainless steel. For example, four valve connectors are connected to the main pipe 1, two of which are first valve connectors 2. Thus, these two first valve connectors 2 are made of flexible stainless steel, which is copper-containing stainless steel. Copper-containing stainless steel gives stainless steel good ductility and flexibility because copper forms a fine dispersed phase in stainless steel, which hinders the movement of dislocations, thereby improving the yield strength of the material. In addition, appropriate amounts of copper can refine the grains and reduce defects at grain boundaries, thereby improving the toughness of the material. Furthermore, the addition of copper can also induce a martensitic phase transformation, thereby improving the strength of stainless steel.

[0073] Therefore, by using flexible stainless steel containing copper, this application enables stainless steel pipes to adapt to complex shape changes and bending requirements without sacrificing their corrosion resistance and mechanical strength. Even after undergoing complex forming processes, such as processing into corrugated pipes or sleeves of specific shapes, they can still maintain good mechanical strength and compressive strength. Flexible stainless steel is easy to bend, weld, and connect. Therefore, when producing valve units, the first valve connector 2 can be integrally formed on the main body pipe 1, and then the first valve connector 2 can be directly connected to the external piping.

[0074] The first connecting pipe 201 and the second connecting pipe 202 of this application are integrally formed, which reduces the welding process between the first connecting pipe 201 and the second connecting pipe 202, thereby reducing production costs. Simultaneously, the integral forming of the first connecting pipe 201 and the second connecting pipe 202 also improves the connection strength and sealing performance between them. Furthermore, valve fittings or bent pipes in related technologies are often made of copper to reduce the welding difficulty, but copper is expensive. In this application, the first connecting pipe 201 and the second connecting pipe 202 are both made of flexible stainless steel. Therefore, the valve unit of this application can significantly reduce production costs.

[0075] According to the valve unit of this utility model embodiment, by making the first connecting pipe 201 and the second connecting pipe 202 integrally formed by flexible stainless steel, the welding process between the first connecting pipe 201 and the second connecting pipe 202 can be reduced, and the connection strength and sealing performance between the first connecting pipe 201 and the second connecting pipe 202 can be improved. Furthermore, flexible stainless steel is less expensive than copper, thereby reducing the production cost of the valve unit.

[0076] In some embodiments of this utility model, 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%.

[0077] 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.

[0078] 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.

[0079] 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.

[0080] In some embodiments of this utility model, the main tube 1 is a flexible stainless steel tube integrally formed.

[0081] For example, there is one first valve connector 2, which is a stainless steel pipe. By making the main body pipe 1 also a stainless steel pipe, the first valve connector 2 can be directly welded to the main body pipe 1. The welding method can be brazing or fusion welding. Brazing can be flame welding or high frequency welding. The welding method is simple and convenient, which can reduce the indirect welding between the first valve connector 2 and the main body pipe 1 through the copper sleeve, reduce the use of copper sleeve and simplify the welding process, thereby reducing the welding cost.

[0082] In one example, the flux used for welding between the flexible stainless steel main tube 1 and the flexible stainless steel first valve tube 2 may contain, by mass percent, 60%-80% boric acid, 5%-15% fluoride, and 10%-20% potassium borate. The solder, by mass percent, contains Cu: 46%-50%, Ni: 9%-11%, Si: 0.04%-0.25%, with the remainder consisting of Zn and unavoidable impurities.

[0083] For example, multiple valve connectors are provided. Some of the valve connectors can be copper pipes or copper alloy pipes. The valve connectors and the main body pipe 1 can also be directly fixedly connected by welding. The welding method can be brazing or fusion welding. Brazing can be flame welding or high-frequency welding. The welding method is simple and convenient, which can reduce the indirect welding between the valve connectors and the main body pipe 1 through copper sleeves, reduce the use of copper sleeves and simplify the welding process, thereby reducing welding costs.

[0084] In one example, the flux used for welding between the flexible stainless steel body tube 1 and the copper or copper alloy valve fitting may contain, by weight, 60%-80% boric acid, 5%-15% fluoride, and 10%-20% potassium borate. The solder, by weight, contains 57%-61% Cu, 1.0%-1.5% Sn, 0.05%-0.2% Si, with the remainder consisting of Zn and unavoidable impurities.

[0085] For example, the valve unit includes multiple valve connectors, each of which is a first valve connector 2. By making the main body tube 1 also a stainless steel tube, the valve connectors and the main body tube 1 can be integrally formed, which can better reduce the welding between the valve connectors and the main body tube 1, and also improve the connection strength and sealing performance between the valve connectors and the main body tube 1. Furthermore, flexible stainless steel is less expensive than copper, thereby reducing the production cost of the valve unit.

[0086] In some embodiments of this utility model, such as Figure 1 and Figure 2 As shown, the first connecting pipe 201 is a straight pipe, which facilitates welding of the first connecting pipe 201 to the main pipe 1.

[0087] In some embodiments of this utility model, the valve unit is a four-way valve, which includes a first valve pipe 21, a second valve pipe 22, a third valve pipe 23, and a fourth valve pipe 24. At least one of the first valve pipe 21, the second valve pipe 22, the third valve pipe 23, and the fourth valve pipe 24 is a first valve connector 2, or at least one of the first valve pipe 21, the second valve pipe 22, the third valve pipe 23, and the fourth valve pipe 24 is a second valve connector 2', or a portion of the first valve pipe 21, the second valve pipe 22, the third valve pipe 23, and the fourth valve pipe 24 is a first valve connector 2, and the remainder is a second valve connector 2'.

[0088] Optionally, the valve unit is a four-way valve 10, and the valve connecting pipe is provided with four valve pipes, namely a first valve pipe 21, a second valve pipe 22, a third valve pipe 23 and a fourth valve pipe 24. For example, the first valve pipe 21, the second valve pipe 22, the third valve pipe 23 and the fourth valve pipe 24 are all first valve connecting pipes 2, that is, the first valve pipe 21, the second valve pipe 22, the third valve pipe 23 and the fourth valve pipe 24 all have a bent pipe 3, and the four bent pipes 3 are respectively the first bent pipe, the second bent pipe, the third bent pipe and the fourth bent pipe. In other words, in the valve unit of this application, the main body pipe 1 is connected to four integrally formed components made of flexible stainless steel. Each integral component includes a bent pipe 3. Thus, the valve unit can be a four-way valve 10. The four bent pipes 3 of the four-way valve 10 enable the four-way valve 10 to better communicate with the components in the HVAC system. At the same time, it can also optimize the layout of the components in the HVAC system. Furthermore, the four first valve connecting pipes 2 of the four-way valve 10 can reduce the welding process of the valve unit and improve the structural strength and sealing performance of the valve unit. Moreover, flexible stainless steel is less expensive than copper, thereby reducing the production cost of the valve unit.

[0089] Optionally, the main tube 1 can be a stainless steel tube, and the main tube 1 is welded to four integral parts formed by flexible stainless steel. The welding method between the flexible stainless steel can be brazing or fusion welding as described in the above example, and the solder and flux can also be the same as those used when welding between the flexible stainless steel in the above example, which will not be elaborated here.

[0090] Optionally, the main tube 1 can be a copper tube or a copper alloy tube. The main tube 1 is welded to four integrated parts integrally formed from flexible stainless steel. The welding method between copper or copper alloy and flexible stainless steel can be brazing or fusion welding as described in the above example. The solder and flux can also be the same solder and flux used when welding flexible stainless steel to flexible stainless steel as described in the above example. This application will not elaborate on this.

[0091] In some embodiments of this utility model, such as Figures 1-3 As shown, multiple valve connectors are provided, some of which are first valve connectors 2 and some of which are second valve connectors 2'. For example, the valve unit also includes at least one second valve connector 2'. The second valve connector 2' includes a third connecting pipe 201' and a fourth connecting pipe 202'. The third connecting pipe 201' is located between the main pipe and the fourth connecting pipe 202'. The fourth connecting pipe 202' is connected to an external piping. The fourth connecting pipe 202' is a straight pipe. The third connecting pipe 201' and the fourth connecting pipe 202' are flexible stainless steel pipes integrally formed.

[0092] For example, four valve connectors are provided. Two of the four valve connectors are first valve connectors 2 with bent pipes 3, and the other two valve connectors are second valve connectors 2' with straight pipes 4. Thus, the main pipe 1 is connected to four integrated parts integrally formed of flexible stainless steel. By having both bent pipes 3 and straight pipes 4 on the valve unit, the flexibility of the valve unit can be improved, and the layout of components in the HVAC system can be better optimized.

[0093] Furthermore, it is understandable that regardless of whether the valve unit has only a bent pipe 3, only a straight pipe 4, or both a bent pipe 3 and a straight pipe 4, the valve connection length is shorter than that of the four-way valve in the related art. In order to adapt to the layout of the internal components of the HVAC system, a transition pipe needs to be connected when connecting the pipes of the components. This application directly constructs the first valve connection 2 and the second valve connection 2', which are longer, which can reduce the welding between pipes, improve the sealing between pipes, and also improve the flexibility of the valve unit while reducing costs.

[0094] In some embodiments of this utility model, the end of the second connecting pipe 202 away from the first connecting pipe 201 is provided with a first retractable portion, the outer diameter of which is smaller than the outer diameter of the first connecting pipe 201; or, the end of the second connecting pipe 202 away from the first connecting pipe 201 is provided with a first expanding portion, the outer diameter of which is larger than the outer diameter of the first connecting pipe 201; and / or, the end of the fourth connecting pipe 202' away from the third connecting pipe 201' is provided with a second retractable portion, the outer diameter of which is smaller than the outer diameter of the third connecting pipe 201'; or, the end of the fourth connecting pipe 202' away from the third connecting pipe 201' is provided with a second expanding portion, the outer diameter of which is larger than the outer diameter of the third connecting pipe 201'.

[0095] like Figure 4 As shown, one end of the bent tube 3 is provided with a retraction part 51 (i.e., the first retraction part or the second retraction part), the outer diameter of the retraction part 51 is smaller than the outer diameter of the bent tube 3; the other end of the bent tube 3 is provided with an expansion part 52 (i.e., the second expansion part or the second expansion part), the outer diameter of the expansion part 52 is larger than the outer diameter of the bent tube 3.

[0096] Taking the bent pipe 3 as an example, an expansion section 52 can be constructed at the opening of the bent pipe 3. The pipe of the component can be inserted into the expansion section 52 and then fixedly connected by welding. After the pipe of the component is inserted into the expansion section 52, since the outer diameter of the expansion section 52 is different from the outer diameter of the bent pipe 3, the pipe of the component can be better limited. Therefore, the welding of the bent pipe 3 and the pipe of the component has good stability. Similarly, a retractable section 51 can be constructed at the opening of the bent pipe 3. The retractable section 51 can be inserted into the pipe of the component. Since the outer diameter of the retractable section 51 is different from the outer diameter of the bent pipe 3, the pipe of the component can be better limited. Therefore, the welding of the bent pipe 3 and the pipe of the component has good stability.

[0097] In addition, the bent tube 3 is made of stainless steel. When manufacturing the expansion part 52 or the retraction part 51, the stainless steel tube has good ductility. Therefore, the opening of the bent tube 3 can be expanded or reduced in one step, which is simple and convenient. The end of the bent tube 3 is not prone to deformation or cracks.

[0098] The above example uses the bent pipe 3 as an example. It can be understood that the opening of the straight pipe 4 can also be constructed with an expansion section 52 or a retraction section 51, which will not be elaborated here.

[0099] In some embodiments of this utility model, in the direction from the first connecting pipe 201 to the second connecting pipe 202, the outer diameter of the first retracted portion gradually decreases, or the outer diameter of the first expanded portion gradually increases; and / or, in the direction from the third connecting pipe 201' to the fourth connecting pipe 202', the outer diameter of the second retracted portion gradually decreases, or the outer diameter of the second expanded portion gradually increases.

[0100] For example, the retraction section 51 includes a plurality of sub-retraction sections connected in sequence, and the outer diameter of the plurality of sub-retraction sections decreases in sequence; or, the expansion section 52 includes a plurality of sub-expansion sections connected in sequence, and the outer diameter of the plurality of sub-expansion sections increases in sequence.

[0101] Taking the retraction section 51, which includes multiple sub-retraction sections, as an example, the flow state transition of fluid between pipes with different outer diameters can be smoothed through multiple sub-retraction sections with progressively decreasing outer diameters. This reduces eddies and energy losses caused by the abrupt change from a pipe with a large outer diameter to a pipe with a small outer diameter, effectively reducing fluid resistance and noise. Furthermore, the gradually changing outer diameter of the multiple sub-retraction sections can act as stress dispersion zones when subjected to high pressure or vibration environments, preventing pipe damage or rupture caused by stress concentration.

[0102] Similarly, taking the expansion section 52 as an example, which includes multiple sub-expansion sections, the flow state transition of fluid between pipes with different outer diameters can be smoothed through multiple sub-expansion sections with progressively increasing outer diameters. This reduces eddies and energy losses caused by the abrupt change from a small outer diameter pipe to a large outer diameter pipe, effectively reducing fluid resistance and noise. Furthermore, the multiple sub-expansion sections with gradually changing outer diameters can act as stress dispersion zones when subjected to high pressure or vibration environments, preventing pipe damage or rupture caused by stress concentration.

[0103] In some embodiments of this utility model, such as Figure 4 As shown, the bent pipe 3 includes a first straight pipe section 301, a bent section 303, and a second straight pipe section 302 connected in sequence. The first straight pipe section 301 and the second straight pipe section 302 are arranged in parallel. The bending radius r of the bent section 303 and the outer diameter d of the first straight pipe section 301 satisfy the following condition: 1.2d ≤ r ≤ 1.5d; the bending radius r of the bent section 303 and the outer diameter d of the second straight pipe section 302 satisfy the following condition: 1.2d ≤ r ≤ 1.5d. Therefore, by ensuring that the bent pipe 3 meets the above conditions, space can be saved effectively, and the layout of the HVAC system can be optimized.

[0104] The bending section 303 includes at least 2-4% Wt of Cu, and / or the yield strength of the bending section 303 is 140-180 MPa, and / or the hardness of the bending section 303 is 100-120 Hv. Compared to existing 304L stainless steel pipes, the flexible stainless steel of this embodiment, by including at least 2-4% Wt of Cu, reduces the yield strength of the stainless steel material by 140-180 MPa and the hardness by 100-120 Hv. Therefore, in the pipe bending process, the flexible stainless steel containing 2-4% Wt of Cu not only achieves a smaller lower limit of the bending radius, but also, during high-speed pipe bending, the flattening offset of the flexible stainless steel containing 2-4% Wt of Cu is less than that of existing 304L stainless steel.

[0105] In some embodiments of this invention, the Md30 of the flexible stainless steel is -50℃ to -80℃. In the field of stainless steel materials, "Md30" refers to the critical temperature for martensitic transformation. Specifically, "Md30" is the temperature at which 50% martensite is formed when 30% deformation occurs. This parameter is crucial for predicting the behavior of stainless steel during processing because the formation of martensite affects the material's hardness and magnetism. Generally, the lower the "Md30" value, the less likely the material is to form martensite under the same deformation conditions. Therefore, the material has stronger resistance to aging cracking, meaning it is less prone to cracking. Conversely, if the "Md30" value is high, the material is more likely to generate martensite during processing, which may lead to cracking. Therefore, by ensuring that the critical temperature for the martensitic transformation of the flexible stainless steel meets the above conditions, the valve unit can operate well in low-temperature environments with good stability.

[0106] In some embodiments of this invention, the flexible stainless steel is austenitic stainless steel with an average grain size of 20 μm to 40 μm. Thus, austenitic stainless steel with a grain size of 20 μm to 40 μm 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 grain refinement.

[0107] This utility model also proposes a heating and ventilation device having a valve unit as described in the above embodiments.

[0108] According to the HVAC device of the present invention, by setting the valve unit of the above embodiment, and by making the first connecting pipe 201 and the second connecting pipe 202 integrally formed by flexible stainless steel, the welding process between the first connecting pipe 201 and the second connecting pipe 202 can be reduced, and the connection strength and sealing performance between the first connecting pipe 201 and the second connecting pipe 202 can be improved. Furthermore, flexible stainless steel is less expensive than copper, thereby reducing the production cost of the valve unit.

[0109] In some embodiments of this utility model, the valve unit is a four-way valve, which includes a first valve pipe 21, a second valve pipe 22, a third valve pipe 23, and a fourth valve pipe 24. The HVAC device also includes a compressor 200, a first outlet pipe 700, and a second outlet pipe 600. The first valve pipe 21 is connected to the exhaust pipe 300 of the compressor 200, the second valve pipe 22 is connected to the suction pipe 400 of the compressor 200, the third valve pipe 23 is connected to the first outlet pipe 700, and the fourth valve pipe 24 is connected to the second outlet pipe 600. At least one of the first valve pipe 21, the second valve pipe 22, the third valve pipe 23, and the fourth valve pipe 24 is a first valve connecting pipe 2.

[0110] like Figures 1-5 , Figures 9-13As shown, the valve unit is a four-way valve 10, with four valve connecting pipes: a first valve pipe 21, a second valve pipe 22, a third valve pipe 23, and a fourth valve pipe 24. The HVAC system also includes a compressor 200, a first outlet pipe 700, and a second outlet pipe 600. The first valve pipe 21 connects to the exhaust pipe 300 of the compressor 200, the second valve pipe 22 connects to the suction pipe 400 of the compressor 200, the third valve pipe 23 connects to the first outlet pipe 700, and the fourth valve pipe 24 connects to the second outlet pipe 600. Using any one of the first valve pipes 21, 22, 23, or 24 of the four-way valve 10 as the first valve connecting pipe 2 reduces the welding process between the valve connecting pipe and the bent pipe 3, improves the connection strength and sealing performance, and, since flexible stainless steel is less expensive than copper, reduces the production cost of the valve unit.

[0111] Understandably, the valve unit can also be a three-way valve, that is, a valve with three connecting pipes, or a five-way valve, that is, a valve with five connecting pipes. By making the valve unit have flexible stainless steel connecting pipes, the valve unit has better structural strength, sealing performance and lower cost.

[0112] In some embodiments of this utility model, the exhaust pipe 300 and the first valve pipe 21 are both integrally formed flexible stainless steel pipes, and are welded together by a first solder 91; and / or, the intake pipe 400 and the second valve pipe 22 are both integrally formed flexible stainless steel pipes, and are welded together by a first solder 91; and / or, the first outlet pipe 700 and the third valve pipe 23 are both integrally formed flexible stainless steel pipes, and are welded together by a first solder 91; and / or, the second outlet pipe 600 and the fourth valve pipe 24 are both integrally formed flexible stainless steel pipes. The integrally formed stainless steel pipe, the second outlet pipe 600 and the fourth valve pipe 24 are welded together by a first solder 91, wherein the first solder 91 contains, by weight, Cu: 46%-50%, Ni: 9%-11%, Si: 0.04%-0.25%, with the remainder consisting of Zn and unavoidable impurities; the flux used when using the first solder 91 contains, by weight, 60%-80% boric acid, 5%-15% fluoride, and 10%-20% potassium borate; the melting temperature t1 when using the first solder 91 satisfies: 910℃≤t1≤935℃; the brazing temperature t2 when using the first solder 91 satisfies: 950℃≤t2≤975℃.

[0113] In some embodiments of this utility model, one of the exhaust pipe 300 and the first valve pipe 21 is a flexible stainless steel pipe integrally formed, and the other is a copper pipe or a copper alloy pipe. The exhaust pipe 300 and the first valve pipe 21 are welded together by a second solder 92. And / or, one of the intake pipe 400 and the second valve pipe 22 is a flexible stainless steel pipe integrally formed, and the other is a copper pipe or a copper alloy pipe. The intake pipe 400 and the second valve pipe 22 are welded together by a second solder 92. And / or, one of the first outlet pipe 700 and the third valve pipe 23 is a flexible stainless steel pipe integrally formed, and the other is a copper pipe or a copper alloy pipe. The first outlet pipe 700 and the third valve pipe 23 are welded together by a second solder 92. And / or, the second outlet pipe 600... One of the four valve tubes 24 is a flexible stainless steel tube integrally formed, and the other is a copper tube or copper alloy tube. The second outlet tube 600 and the fourth valve tube 24 are welded together by a second solder 92. The second solder 92 contains, by weight, 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 92 contains, by weight, 60%-80% boric acid, 5%-15% fluoride, and 10%-20% potassium borate. The melting temperature t1 when using the second solder 92 satisfies: 880℃≤t1≤890℃. The brazing temperature t2 when using the second solder 92 satisfies: 920℃≤t2≤930℃.

[0114] like Figures 1-3 , Figures 9-13 As shown, in the HVAC device according to the embodiment of the present utility model, the valve unit is a four-way valve 10. The HVAC device also includes a stop valve 20 and a first pipe structure 30. The four-way valve 10, the stop valve 20 and the first pipe structure 30 constitute a four-way valve assembly 100. That is, the four-way valve assembly 100 includes a four-way valve 10, a stop valve 20 and a first pipe structure 30. The first pipe structure 30 is welded and connected between the four-way valve 10 and the stop valve 20. At least part of the first pipe structure 30 is a flexible stainless steel integrally formed stainless steel part.

[0115] 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 undergoing complex forming processes, such as processing into corrugated pipes or sleeves of specific shapes, it can still maintain good mechanical strength and compressive strength. Flexible stainless steel is easy to bend, weld and connect.

[0116] In this application, at least a portion of the first tube structure 30 is made of stainless steel. That is, a part of the first tube structure 30 may be a flexible stainless steel tube, or the first tube structure 30 may be an integrally formed flexible stainless steel component. Specifically, the tube body in which a portion of the first tube structure 30 is made of flexible stainless steel can be understood as follows: Flexible stainless steel can be used at bending points according to the actual needs of the first tube structure 30. This allows the first tube structure 30 to adapt to complex shape changes and bending requirements without sacrificing its corrosion resistance and mechanical strength. Flexible stainless steel can also be used at stress concentration points in the first tube structure 30, thus maintaining good mechanical strength and compressive strength at these stress concentration points. Furthermore, the welding points between the first tube structure 30 and the four-way valve 10, or between the first tube structure 30 and the stop valve 20, can also be made of flexible stainless steel. At these welding points, the first tube structure 30 can be directly welded to copper or copper alloy structures. The welding method can be brazing or fusion welding as described in the above examples, and the solder and flux can be the same as those used for welding flexible stainless steel to copper or copper alloys as described in the above examples, which will not be elaborated upon here.

[0117] Therefore, according to the embodiment of the present utility model, the four-way valve assembly 100, by making at least a portion of the first pipe structure 30 a flexible stainless steel integrally formed stainless steel part, can better bend the first pipe structure 30 according to actual needs, or improve the local structural strength of the first pipe structure 30, or reduce the welding difficulty of the first pipe structure 30 and improve the welding efficiency of the first pipe structure 30.

[0118] In some embodiments of this utility model, such as Figures 1-3 , Figures 9-13As shown, the first pipe structure 30 includes a filter 61, and the piping between the filter 61 and the shut-off valve 20 is a first piping 62. The first piping 62 is a flexible stainless steel pipe integrally formed. By making the first piping 62 between the filter 61 and the shut-off valve 20 a flexible stainless steel pipe integrally formed, the first piping 62 can be better connected to the filter 61 and the shut-off valve 20. For example, the filter 61 can be integrally formed with the first piping 62. By making the first piping 62 a flexible stainless steel pipe integrally formed, the first piping 62 can be better welded to the shut-off valve 20. For example, the filter 61 and the first piping 62 are two separate structural components, and the first piping 62 can also be better welded to the filter 61. In addition, since the first pipe 62 is a flexible stainless steel pipe integrally formed, the structure of the first pipe 62 can be designed well according to actual needs. The structural design includes the bending design of the first pipe 62 and the design of the flaring or shrinking of the pipe opening of the first pipe 62. Thus, the first pipe 62 can have high flexibility.

[0119] Optionally, the first pipe structure 30 is a flexible stainless steel integrally formed stainless steel part. That is, both the filter element and the first pipe 62 are made of flexible stainless steel. The filter element and the first pipe 62 can be integrated parts of flexible stainless steel. This can reduce the welding between the filter element and the first pipe 62, and also improve the connection strength and sealing between the filter element and the first pipe 62. In addition, flexible stainless steel is less expensive than copper, thereby reducing the production cost of the filter element and the first pipe 62.

[0120] In some embodiments of this utility model, the shut-off valve 20 includes a shut-off valve tube, which is a flexible stainless steel tube integrally formed. The shut-off valve tube is welded to the first piping. That is, both the shut-off valve tube and the first piping 62 are made of flexible stainless steel. Therefore, the shut-off valve tube and the first piping 62 can be directly welded together. The welding method can be brazing or fusion welding. Brazing can be flame welding or high-frequency welding. The welding method is simple and convenient, which can reduce the indirect welding between the shut-off valve tube and the first piping 62 through the copper sleeve. It can reduce the use of copper sleeve and simplify the welding process, thereby reducing the welding cost.

[0121] In one example, the flux used for welding between the flexible stainless steel body pipe 1 and the flexible stainless steel valve fitting may consist of, by mass percent, 60%-80% boric acid, 5%-15% fluoride, and 10%-20% potassium borate. The solder, by mass percent, contains Cu: 57%-61%, Sn: 1.0%-1.5%, Si: 0.05%-0.2%, with the remainder consisting of Zn and unavoidable impurities.

[0122] In some embodiments of this utility model, such as Figures 1-3 , Figures 9-13 As shown, the first pipe structure 30 includes a filter 61, and the piping between the four-way valve 10 and the filter 61 is a second piping 63, which is a flexible stainless steel pipe integrally formed. By making the second piping 63 between the four-way valve 10 and the filter 61 a flexible stainless steel pipe integrally formed, the second piping 63 can be better connected to the four-way valve 10 and the filter 61. For example, the filter 61 can be integrally formed with the second piping 63, and by making the second piping 63 a flexible stainless steel pipe integrally formed, the second piping 63 can be better welded to the four-way valve 10; for example, the filter 61 and the second piping 63 are two separate structural components, and the second piping 63 can also be better welded to the filter 61. In addition, since the second pipe 63 is a flexible stainless steel pipe integrally formed, the structure of the second pipe 63 can be designed well according to actual needs. The structural design includes the bending design of the second pipe 63 and the design of the flaring or shrinking of the pipe opening of the second pipe 63. As a result, the second pipe 63 can have high flexibility.

[0123] Optionally, the first pipe structure 30 is a one-piece molded stainless steel component made of flexible stainless steel. That is, both the filter element and the second pipe 63 are made of flexible stainless steel. The filter element and the second pipe 63 can be integrated components of flexible stainless steel. In some examples, the filter element, the first pipe 62 and the second pipe 63 are all made of flexible stainless steel. The filter element, the first pipe 62 and the second pipe 63 can be integrated components of flexible stainless steel. This can effectively reduce the welding of the first pipe structure 30, improve the connection strength and sealing performance of the first pipe structure 30, and since flexible stainless steel is less expensive than copper, the production cost of the first pipe structure 30 can be reduced.

[0124] In some embodiments of this utility model, such as Figures 1-3 , Figures 9-13As shown, the four-way valve 10 includes a valve connector, which is a flexible stainless steel tube integrally formed and welded to the second piping 63. The four-way valve 10 has a first valve pipe 21, a second valve pipe 22, a third valve pipe 23, and a fourth valve pipe 24. The first valve pipe 21 is connected to the exhaust pipe 300 of the compressor 200, the second valve pipe 22 is connected to the suction pipe 400 of the compressor 200, the third valve pipe 23 is connected to the first pipe structure 30, which is the first outlet pipe 700, and the fourth valve pipe 24 is connected to the second outlet pipe 600. By making the third valve pipe 23 a stainless steel tube, in one example, the third valve pipe 23 and the second piping 63 are welded together. Welding the third valve pipe 23 to the second piping 63 can be a simple and convenient weld between flexible stainless steel components. In one example, the third valve pipe 23 and the second piping 63 are integrally formed components; this application does not impose limitations.

[0125] Optionally, the first pipe structure 30 is a flexible stainless steel component, and the four-way valve 10 includes a valve connector, wherein the valve connector and the first pipe structure 30 are integrally formed flexible stainless steel components.

[0126] In some embodiments of this utility model, the shut-off valve 20 includes a shut-off valve tube, which is a flexible stainless steel tube integrally formed. Optionally, the first piping 62 welded to the shut-off valve 20 is also a flexible stainless steel tube integrally formed. The shut-off valve 20 and the first piping 62 can be directly welded between flexible stainless steel components, which is simple and convenient. In one example, the shut-off valve 20 and the first piping 62 are integrally formed integrated components, which is not a limitation of this application.

[0127] In one example, the shut-off valve 20 includes a shut-off valve tube, which is a flexible stainless steel tube integrally formed. Optionally, the first tube structure 30 is a flexible stainless steel component, and the shut-off valve tube and the first tube structure 30 are an integrated component integrally formed from flexible stainless steel.

[0128] In some embodiments of this utility model, the valve connector of the four-way valve 10 is welded with a sleeve, namely a first sleeve 87, which is a copper sleeve or a copper alloy sleeve. That is to say, the valve connector can be indirectly welded to other pipelines through the first sleeve 87. For example, the valve connector is a third valve pipe 23, which can be indirectly welded to the first piping 62. That is, the first sleeve 87 is welded to the port of the third valve pipe 23, and then the first piping 62 can be welded to the first sleeve 87, thereby realizing the welded connection between the third valve pipe 23 and the first piping 62. Of course, the valve connector can also be a first valve pipe 21, a second valve pipe 22, or a fourth valve pipe 24, which is not limited in this application.

[0129] In some embodiments of this utility model, a sleeve, namely a second sleeve 88, is welded to the end of the first pipe structure 30 facing the four-way valve 10. The second sleeve 88 is a copper pipe or a copper alloy pipe. That is, the second sleeve 88 is welded to the end of the first pipe 62, so that the first pipe 62 and the third valve pipe 23 can be indirectly welded through the second sleeve 88. Alternatively, the first sleeve 87 can also be welded to the end of the third valve pipe 23. In this way, the second sleeve 88 can be pre-welded to the end of the first pipe 62, and the first sleeve 87 can be welded to the end of the third valve pipe 23. Then, the welding connection between the first pipe 62 and the third valve pipe 23 is achieved by welding the first sleeve 87 and the second sleeve 88.

[0130] In some embodiments of this utility model, a third sleeve is welded to the pipe opening of the first pipe structure 30 facing the shut-off valve 20. The third sleeve is a copper pipe or a copper alloy pipe. That is, the pipe opening of the second pipe 63 is welded with the third sleeve, and the second pipe 63 and the shut-off valve 20 can be indirectly welded together through the third sleeve.

[0131] In some embodiments of this utility model, the valve port of the shut-off valve 20 is welded with a fourth sleeve, which is a copper pipe or a copper alloy pipe. Thus, the shut-off valve 20 and the second piping 63 are indirectly welded together through the fourth sleeve. Alternatively, the valve port of the second piping 63 is welded with a third sleeve. In this way, the fourth sleeve can be pre-welded to the valve port of the shut-off valve 20, and the third sleeve can be pre-welded to the valve port of the second piping 63. The welding connection between the second piping 63 and the shut-off valve 20 is then achieved through the welding between the third sleeve and the fourth sleeve.

[0132] In some embodiments of this utility model, the first pipe structure 30 includes a filter 61 and a first pipe 62 and a second pipe 63 connected to both ends of the filter 61. Both the first pipe 62 and the second pipe 63 are stainless steel pipes. The first pipe 62 has at least one bent section with a bending radius of r. The outer diameter d of either the first pipe 62 or the second pipe 63 satisfies: 1.2d ≤ r ≤ 1.5d. Therefore, by ensuring that the bent pipe 3 meets the above conditions, space can be saved effectively, and the layout of the HVAC system can be optimized.

[0133] In the first embodiment of this utility model, the four-way valve assembly 100 includes a first welded tube 81 and a second welded tube 82 welded together. Both the first welded tube 81 and the second welded tube 82 are made of flexible stainless steel. The first welded tube 81 and the second welded tube 82 are welded together by a first solder 91. The first solder 91 contains, by weight, Cu: 46%–50%, Ni: 9%–11%, Si: 0.04%–0.25%, with the remainder consisting of Zn and unavoidable impurities. The flux used when using the first solder 91 contains, by weight, 60%–80% boric acid, 5%–15% fluoride, and 10%–20% potassium borate. The melting temperature t1 when using the first solder 91 satisfies: 910℃≤t1≤935℃. The brazing temperature t2 when using the first solder 91 satisfies: 950℃≤t2≤975℃.

[0134] In the second embodiment of this utility model, the four-way valve assembly 100 includes a third welded tube 83 and a fourth welded tube 84 welded together. The third welded tube 83 is a flexible stainless steel tube integrally formed, and the fourth welded tube 84 is a copper tube or a copper alloy tube. The third welded tube 83 and the fourth welded tube 84 are welded together by a second solder 92. The second solder 92 contains, by weight, 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 92 contains, by weight, 60%-80% boric acid, 5%-15% fluoride, and 10%-20% potassium borate. The melting temperature t1 when using the second solder 92 satisfies: 880℃≤t1≤890℃. The brazing temperature t2 when using the second solder 92 satisfies: 920℃≤t2≤930℃.

[0135] In the third embodiment of this utility model, the four-way valve assembly 100 includes a fifth welded pipe 85 and a sixth welded pipe 86 welded together. The pipe end of the fifth welded pipe 85 is welded with a first sleeve 87, and the pipe end of the sixth welded pipe 86 is welded with a second sleeve 88. The first sleeve 87 and the second sleeve 88 are welded together by a third solder 93 or a fourth solder 94. The first sleeve 87 is a copper sleeve or a copper alloy sleeve; the second sleeve 88 is a copper sleeve or a copper alloy sleeve; the third solder 93 is tin bronze solder; and the fourth solder 94 is silver copper solder.

[0136] For the three examples above, the first welded pipe 81, the second welded pipe 82, the third welded pipe 83, the fourth welded pipe 84, the fifth welded pipe 85, and the sixth welded pipe 86 can be any pipe body in the four-way valve assembly 100. For example, the first welded pipe 81 is a shut-off valve pipe, and the second welded pipe 82 is a first piping; for example, the first welded pipe 81 is a valve connecting pipe, and the second welded pipe 82 is a second piping. Only two examples are given here for illustration and should not be used as a limitation of this application. In addition, this application will not elaborate on the examples of other pipe bodies.

[0137] This utility model also proposes a compressor assembly 1000.

[0138] like Figures 1-3 As shown, the compressor assembly 1000 according to an embodiment of the present invention includes a compressor 200, an exhaust pipe 300 and an intake pipe 400. One end of the exhaust pipe 300 is connected to the exhaust pipe of the compressor 200, and one end of the intake pipe 400 is connected to the intake pipe of the compressor 200. At least one of the exhaust pipe 300 and the intake pipe 400 is a stainless steel pipe made of flexible stainless steel, and the material composition of the flexible stainless steel includes at least Cu.

[0139] 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 sacrificing its corrosion resistance and mechanical strength. Even after complex forming processes, such as processing into corrugated pipes or sleeves of specific shapes, it still maintains good mechanical strength and compressive strength. Flexible stainless steel is easy to bend, weld, and connect. By making the exhaust pipe 300 or intake pipe 400 a flexible stainless steel pipe, it is possible to effectively bend and extend the exhaust pipe 300 or intake pipe 400, thus saving space and optimizing the layout of the HVAC system. Furthermore, because the exhaust pipe 300 or intake pipe 400 retains good mechanical strength and compressive strength after bending, it can stably transport refrigerant, which is beneficial to the stability of the compressor 200 and the HVAC system.

[0140] According to the compressor assembly 1000 of this utility model embodiment, by making the exhaust pipe 300 or the suction pipe 400 a flexible stainless steel pipe, the exhaust pipe 300 or the suction pipe 400 can be bent and extended more effectively, thus saving space and optimizing the layout of the HVAC system. Furthermore, since the exhaust pipe 300 or the suction pipe 400 retains good mechanical strength and compressive strength after bending, it can stably transport the refrigerant, which is beneficial to the stability of the compressor 200 and the HVAC system operation.

[0141] In some embodiments of this utility model, the exhaust pipe 300 is a stainless steel pipe made of flexible stainless steel, and the exhaust pipe 300 has multiple bending positions, and / or, the intake pipe 400 is a stainless steel pipe made of flexible stainless steel, and the intake pipe 400 has multiple bending positions.

[0142] Reference Appendix Figure 5 As shown, the exhaust pipe 300 includes a first intake pipe and a second intake pipe connected together. The first intake pipe includes a first exhaust straight pipe 71, a second exhaust straight pipe 72, and an intake bend. The intake bend connects the first exhaust straight pipe 71 and the second exhaust straight pipe 72. The end of the second exhaust straight pipe 72 furthest from the intake bend is connected to the second intake pipe. The diameters of the first exhaust straight pipe 71 and the second exhaust straight pipe 72 are both d, and the bending radius of the intake bend is r, satisfying 1.2d ≤ r ≤ 1.5d.

[0143] Figure 5 In the example shown, an oil separator 800 is connected to the end of the exhaust pipe 500 facing the four-way valve 100. Figure 9 In the example shown, the oil separator 800 is located between the two exhaust pipes 300.

[0144] The first exhaust straight pipe 71 has a limiting part at the end away from the intake bend that cooperates with the limiting part of the external intake pipe. The limiting part is a convex bulge or an annular protrusion extending around the axis of the first exhaust straight pipe 71.

[0145] The second intake piping includes multiple exhaust straight pipes 4, which include a third exhaust straight pipe 73, a fourth exhaust straight pipe 74, a fifth exhaust straight pipe 75, and a sixth exhaust straight pipe 76 connected in sequence. The third exhaust straight pipe 73, the fourth exhaust straight pipe 74, the fifth exhaust straight pipe 75, and the sixth exhaust straight pipe 76 are all bent in pairs, and the direction of the bends can be the same or different.

[0146] For example, the first exhaust straight pipe 71, the second exhaust straight pipe 72, and the sixth exhaust straight pipe 76 are all arranged in parallel.

[0147] One end of the first intake pipe is welded with a copper sleeve or a copper alloy sleeve.

[0148] In some embodiments of this utility model, such as Figures 1-3 , Figures 9-13As shown, the compressor assembly 1000 also includes a four-way valve 10, which includes a main body pipe 1 and four valve connecting pipes. The four valve connecting pipes of the four-way valve 10 are a first valve pipe 21, a second valve pipe 22, a third valve pipe 23, and a fourth valve pipe 24. The first valve pipe 21 is connected to the exhaust pipe 300, the second valve pipe 22 is connected to the suction pipe 400, the third valve pipe 23 is connected to the first outlet pipe 700, and the fourth valve pipe 24 is connected to the second outlet pipe 600. At least one of the first valve pipe 21, the second valve pipe 22, the third valve pipe 23, and the fourth valve pipe 24 is a stainless steel pipe.

[0149] like Figures 1-3 , Figures 9-13 As shown, at least one of the first valve tube 21, the second valve tube 22, the third valve tube 23 and the fourth valve tube 24 has a bent pipe 3 connected to its other end. The bent pipe 3 is a stainless steel pipe.

[0150] like Figures 1-3 , Figures 9-13 As shown, in one example, the other end of the first valve pipe 21 is connected to the exhaust pipe 300 of the compressor 200, and the bent pipe 3 is connected between the first valve pipe 21 and the exhaust pipe 300; the other end of the second valve pipe 22 is connected to the suction pipe 400 of the compressor 200, and the bent pipe 3 is connected between the second valve pipe 22 and the suction pipe 400; the other end of the third valve pipe 23 is connected to the first outlet pipe 700, and the bent pipe 3 is connected between the third valve pipe 23 and the first outlet pipe 700; the other end of the fourth valve pipe 24 is connected to the second outlet pipe 600, and the bent pipe 3 is connected between the fourth valve pipe 24 and the second outlet pipe 600.

[0151] Optionally, the outer diameter of the valve pipe connected to the bent pipe 3 is d, and the bending radius of the bent pipe 3 is r, satisfying: 1.2d≤r≤1.5d.

[0152] In some embodiments of this utility model, at least one of the first valve pipe 21, the second valve pipe 22, the third valve pipe 23 and the fourth valve pipe 24 has a sleeve welded to its opening, and the sleeve is a copper sleeve or a copper alloy sleeve.

[0153] In some embodiments of this utility model, a sleeve is welded to the end of the exhaust pipe 300 facing the four-way valve 10. The sleeve is a copper sleeve or a copper alloy sleeve.

[0154] In some embodiments of this utility model, a sleeve is welded to the end of the suction pipe 400 facing the four-way valve 10. The sleeve is a copper sleeve or a copper alloy sleeve.

[0155] Optionally, all pipelines in this application, regardless of whether they are made of flexible stainless steel, can have sleeves welded at the pipe ends. The sleeves can be copper sleeves or copper alloy sleeves, so that when welding two adjacent pipelines, indirect welding can be performed through the sleeves. When two adjacent pipelines are both made of flexible stainless steel, the sleeves can be selected or not selected depending on the actual situation. If the sleeves are not selected, the flexible stainless steel can be directly welded to the flexible stainless steel. The welding method can be brazing. The solder and flux have been described in the above examples and will not be repeated here.

[0156] In some embodiments of this utility model, the four-way valve 10 is a flexible stainless steel valve.

[0157] In some embodiments of this utility model, such as Figure 13 and Figure 16 As shown, the compressor assembly includes a first welded tube 81 and a second welded tube 82 welded together. Both the first welded tube 81 and the second welded tube 82 are made of flexible stainless steel. The first welded tube 81 and the second welded tube 82 are welded together by a first solder 91. The first solder 91 contains, by weight, Cu: 46%–50%, Ni: 9%–11%, Si: 0.04%–0.25%, with the remainder consisting of Zn and unavoidable impurities. The flux used when using the first solder 91 contains, by weight, 60%–80% boric acid, 5%–15% fluoride, and 10%–20% potassium borate. The melting temperature t1 when using the first solder 91 satisfies: 910℃≤t1≤935℃. The brazing temperature t2 when using the first solder 91 satisfies: 950℃≤t2≤975℃.

[0158] In some embodiments of this utility model, such as Figure 14 and Figure 17 As shown, the compressor assembly includes a third welded tube 83 and a fourth welded tube 84 welded together. The third welded tube 83 is a flexible stainless steel tube integrally formed, and the fourth welded tube 84 is a copper tube or a copper alloy tube. The third welded tube 83 and the fourth welded tube 84 are welded together by a second solder 92. The second solder 92 contains, by weight, 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 92 contains, by weight, 60%-80% boric acid, 5%-15% fluoride, and 10%-20% potassium borate. The melting temperature t1 when using the second solder 92 satisfies: 880℃≤t1≤890℃. The brazing temperature t2 when using the second solder 92 satisfies: 920℃≤t2≤930℃.

[0159] In some embodiments of this utility model, such as Figure 12 and Figure 15As shown, the compressor assembly includes a fifth welded tube 85 and a sixth welded tube 86 welded together. The fifth welded tube 85 has a first sleeve 87 welded to its end, and the sixth welded tube 86 has a second sleeve 88 welded to its end. The first sleeve 87 and the second sleeve 88 are welded together by a third solder 93 or a fourth solder 94. The first sleeve 87 is a copper sleeve or a copper alloy sleeve; the second sleeve 88 is a copper sleeve or a copper alloy sleeve; the third solder 93 is a tin bronze solder; and the fourth solder 94 is a silver copper solder.

[0160] For the three examples above, the first welded pipe 81, the second welded pipe 82, the third welded pipe 83, the fourth welded pipe 84, the fifth welded pipe 85, and the sixth welded pipe 86 can be any pipe body in the compressor assembly 1000. For example, the first welded pipe 81 is a shut-off valve pipe, and the second welded pipe 82 is a first piping; for example, the first welded pipe 81 is a valve connecting pipe, and the second welded pipe 82 is a second piping. Only two examples are given here for illustration and should not be used as a limitation of this application. In addition, this application will not elaborate on the examples of other pipe bodies.

[0161] This utility model also proposes a heating and ventilation device.

[0162] like Figures 1-16 As shown, the HVAC system according to this embodiment of the present invention may include a compressor assembly 1000, an indoor heat exchanger 2000, and an outdoor heat exchanger 3000. The indoor unit 4000 includes the indoor heat exchanger 2000, and the outdoor unit 5000 includes the compressor assembly 1000 and the outdoor heat exchanger 3000. The compressor assembly 1000 includes a compressor 200, an exhaust pipe 300, an intake pipe 400, and a four-way valve assembly 100. The four-way valve assembly 100 includes a four-way valve 10, a shut-off valve 20, and a first pipe structure 30. The first valve pipe 21 of the four-way valve 10 is connected to the exhaust pipe 300 via a gas-liquid separator 500.

[0163] According to the HVAC device of the present utility model embodiment, by providing the four-way valve assembly 100 of the above embodiment, and by making at least a portion of the first pipe structure 30 a flexible stainless steel part, the first pipe structure 30 can be bent or the local structural strength of the first pipe structure 30 can be improved according to actual needs, or the welding difficulty of the first pipe structure 30 can be reduced, thereby improving the welding efficiency of the first pipe structure 30.

[0164] According to the HVAC system of this embodiment, by incorporating the compressor assembly 1000 described above, and by making the exhaust pipe 300 or intake pipe 400 a stainless steel pipe, the exhaust pipe 300 or intake pipe 400 can be bent and extended more effectively, thus saving space and optimizing the layout of the HVAC system. Furthermore, since the exhaust pipe 300 or intake pipe 400 retains good mechanical strength and compressive strength after bending, it can stably transport the refrigerant, which is beneficial to the stability of the compressor 200 and the HVAC system's operation.

[0165] Other components and operations of the valve unit, four-way valve assembly 100, compressor assembly 1000, and HVAC system according to embodiments of the present invention are known to those skilled in the art and will not be described in detail here.

[0166] In some embodiments of this utility model, the four-way valve assembly 100 or the compressor assembly 1000 can also be used in heat pumps, refrigerators and other thermal management products, and this utility model does not impose any limitations.

[0167] The stainless steel pipe involved in this utility model has significantly higher mechanical properties than copper, thus greatly increasing the possibility of using high-pressure flammable new refrigerants in piping compared to copper pipes.

[0168] The stainless steel pipe involved in this utility model has significantly higher mechanical properties than copper, and therefore can withstand stronger high-frequency vibrations caused by the impact of the compressor 200 and refrigerant compared to copper pipes.

[0169] The stainless steel pipe involved in this utility model has significantly higher mechanical properties than copper, so the pipe wall thickness can be reduced by 10-30% compared to copper pipe in the same application scenario.

[0170] The stainless steel pipe involved in this utility model has a lower pipe wall thickness than the copper pipe in the same application scenario, while the outer diameter remains unchanged. Therefore, the diameter of the refrigerant flow channel is larger, and the pressure loss of the refrigerant circulation flow is lower.

[0171] The stainless steel pipe involved in this invention has a lower pitting corrosion potential, lower pitting corrosion weight loss and lower martensitic transformation temperature due to the addition of Cr and Ni elements. This makes it more difficult for the stainless steel pipe to undergo martensitic phase transformation during processing, thereby achieving stronger resistance to pitting corrosion and stress corrosion, and it can be directly flame welded without annealing.

[0172] The stainless steel pipe involved in this invention has a lower carbon content, making it more difficult for it to pass through the material sensitization range during hot working and welding. This effectively controls the formation of M23C6, thereby achieving stronger resistance to intergranular corrosion and effectively reducing welding defects.

[0173] The stainless steel pipe involved in this utility model has low yield strength and high elongation, thus possessing processing performance close to that of copper pipes. It can be processed using equipment for processing copper pipes, such as flanging, bending, flaring, and necking. Unlike traditional stainless steel flanging processes that require punching before flanging, stainless steel pipes can be punched and flanged in a single step, just like copper pipes.

[0174] The stainless steel pipe involved in this invention possesses near-copper pipe processing performance and significantly superior mechanical properties, thus allowing for shorter piping lengths and lower bending radii, enabling more space-saving piping structure designs. In terms of processing, copper pipes typically require a bending radius of at least 1.8 times their outer diameter; while flexible stainless steel, due to its better toughness, can theoretically achieve a bending radius of 1.2 to 1.5 times its outer diameter. Furthermore, because stainless steel has better strength than copper, stronger resistance to vibration stress, and is less prone to vibration cracking, the number of bends required in the refrigerant piping system to reduce vibration stress can be reduced, thereby saving piping space and decreasing the overall size of the unit.

[0175] The tube body made of flexible stainless steel in this invention has the advantages mentioned above, so the tube wall can be made thinner, thereby achieving a lightweight design.

[0176] In some embodiments of this utility model, the HVAC device further includes a third piping, and the compressor assembly has a seventh welded pipe welded to the third piping. Both the seventh welded pipe and the third piping are stainless steel pipes made of flexible stainless steel. The seventh welded pipe and the third piping are welded together by a first solder 91. The first solder 91 contains, by weight, 46%–50% Cu, 9%–11% Ni, 0.04%–0.25% Si, with the remainder consisting of Zn and unavoidable impurities. The flux used with the first solder 91 contains, by weight, 60%–80% boric acid, 5%–15% fluoride, and 10%–20% potassium borate. The melting temperature t1 when using the first solder 91 satisfies: 910℃ ≤ t1 ≤ 935℃. The brazing temperature t2 when using the first solder 91 satisfies: 950℃ ≤ t2 ≤ 975℃.

[0177] In some embodiments of this utility model, the HVAC device further includes a fourth piping, and the compressor assembly has an eighth welded pipe welded to the fourth piping. A third sleeve is welded to the end of the eighth welded pipe, and a fourth sleeve is welded to the end of the fourth piping. The third sleeve and the fourth sleeve are welded together by a third solder 93 or a fourth solder 94, wherein the third sleeve is a copper sleeve or a copper alloy sleeve; the fourth sleeve is a copper sleeve or a copper alloy sleeve; the third solder 93 is a tin bronze solder; and the fourth solder 94 is a silver copper solder.

[0178] In some embodiments of this utility model, the HVAC device further includes a fifth piping, and the compressor assembly has a ninth welded pipe welded to the fifth piping. One of the fifth piping and the ninth welded pipe is a flexible stainless steel pipe integrally formed, and the other is a copper pipe or a copper alloy pipe. The fifth piping and the ninth welded pipe are welded together by a second solder 92, wherein the second solder 92 contains, by weight, 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 92 contains, by weight, 60%-80% boric acid, 5%-15% fluoride, and 10%-20% potassium borate; the melting temperature t1 when using the second solder 92 satisfies: 880℃≤t1≤890℃; the brazing temperature t2 when using the second solder 92 satisfies: 920℃≤t2≤930℃.

[0179] The third, fourth, and fifth pipes, as well as the seventh, eighth, and ninth welded pipes in the above examples, can be any pipe body that can be welded to each other in the HVAC system of this application, and this application does not impose any restrictions.

[0180] 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.

[0181] 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 valve unit, characterized in that, The valve unit includes: Main pipe; At least one first valve connector, the first valve connector including a first connecting pipe and a second connecting pipe, the first connecting pipe being located between the main pipe and the second connecting pipe, the second connecting pipe being connected to an external piping, wherein the second connecting pipe is a bent pipe, and the first connecting pipe and the second connecting pipe are integrally formed flexible stainless steel pipes, the flexible stainless steel being copper-containing stainless steel.

2. The valve unit according to claim 1, characterized in that, The main tube is a stainless steel tube integrally formed from flexible stainless steel.

3. The valve unit according to claim 1, characterized in that, The main tube and the first valve tube are integrally formed stainless steel parts made of the flexible stainless steel.

4. The valve unit according to claim 1, characterized in that, The first connecting pipe is a straight pipe.

5. The valve unit according to claim 1, characterized in that, The valve unit further includes at least one second valve connector, which includes a third connecting pipe and a fourth connecting pipe. The third connecting pipe is located between the main pipe and the fourth connecting pipe, and the fourth connecting pipe is connected to an external piping. The fourth connecting pipe is a straight pipe, and the third connecting pipe and the fourth connecting pipe are integrally formed stainless steel pipes of the flexible stainless steel.

6. The valve unit according to claim 5, characterized in that, The third connecting pipe is a straight pipe.

7. The valve unit according to claim 5, characterized in that, The second connecting pipe has a first retractable portion at its end away from the first connecting pipe, the outer diameter of the first retractable portion being smaller than the outer diameter of the first connecting pipe; or, the second connecting pipe has a first expanding portion at its end away from the first connecting pipe, the outer diameter of the first expanding portion being larger than the outer diameter of the first connecting pipe; and / or, The fourth connecting pipe has a second retractable portion at its end away from the third connecting pipe, and the outer diameter of the second retractable portion is smaller than the outer diameter of the third connecting pipe; or, the fourth connecting pipe has a second expansion portion at its end away from the third connecting pipe, and the outer diameter of the second expansion portion is larger than the outer diameter of the third connecting pipe.

8. The valve unit according to claim 7, characterized in that, In the direction from the first connecting pipe to the second connecting pipe, the outer diameter of the first retracted portion gradually decreases, or the outer diameter of the first expanded portion gradually increases; and / or, In the direction from the third connecting pipe to the fourth connecting pipe, the outer diameter of the second retracted portion gradually decreases, or the outer diameter of the second expanded portion gradually increases.

9. The valve unit according to claim 5, characterized in that, The valve unit is a four-way valve, comprising a first valve tube, a second valve tube, a third valve tube, and a fourth valve tube, wherein... At least one of the first valve pipe, the second valve pipe, the third valve pipe, and the fourth valve pipe is the first valve pipe connection, or, At least one of the first valve pipe, the second valve pipe, the third valve pipe, and the fourth valve pipe is the second valve pipe connection, or, A portion of the first valve tube, the second valve tube, the third valve tube, and the fourth valve tube constitutes the first valve tube connection, while the remainder constitutes the second valve tube connection.

10. The valve unit according to claim 1, characterized in that, The second connecting pipe includes a first straight pipe section, a bent section, and a second straight pipe section connected in sequence. The first straight pipe section and the second straight pipe section are arranged in parallel. The bending radius of the bent section is r. The outer diameter d of the first straight pipe section or the second straight pipe section satisfies: 1.2d≤r≤1.5d.

11. The valve unit according to any one of claims 1-10, characterized in that, 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.

12. The valve unit according to any one of claims 1-10, characterized in that, The flexible stainless steel is austenitic stainless steel, and the average grain size of the flexible stainless steel is 20μm to 40μm.

13. The valve unit according to any one of claims 1-10, characterized in that, The wall thickness of stainless steel pipes is 1.2mm to 1.5mm.

14. A heating, ventilation, and air conditioning (HVAC) device, characterized in that, The valve unit includes any one of claims 1-13.

15. The HVAC system according to claim 14, characterized in that, The valve unit is a four-way valve, comprising a first valve pipe, a second valve pipe, a third valve pipe, and a fourth valve pipe. The HVAC system further includes a compressor, a first outlet pipe, and a second outlet pipe. The first valve pipe is connected to the discharge pipe of the compressor, the second valve pipe is connected to the suction pipe of the compressor, the third valve pipe is connected to the first outlet pipe, and the fourth valve pipe is connected to the second outlet pipe. At least one of the first valve tube, the second valve tube, the third valve tube, and the fourth valve tube is the first valve tube.

16. The HVAC system according to claim 15, characterized in that, Both the exhaust pipe and the first valve pipe are integrally formed flexible stainless steel pipes, and / or, Both the intake pipe and the second valve pipe are integrally formed flexible stainless steel pipes; and / or, Both the first outlet pipe and the third valve pipe are integrally formed flexible stainless steel pipes; and / or, Both the second outlet pipe and the fourth valve pipe are integrally formed stainless steel pipes made of flexible stainless steel.

17. The HVAC system according to claim 15, characterized in that, One of the exhaust pipe and the first valve pipe is a flexible stainless steel pipe integrally formed from stainless steel, and the other is a copper pipe or a copper alloy pipe, and / or, One of the intake pipe and the second valve pipe is a flexible stainless steel pipe integrally formed, and the other is a copper pipe or a copper alloy pipe; and / or, One of the first outlet pipe and the third valve pipe is a flexible stainless steel pipe integrally formed from stainless steel, and the other is a copper pipe or a copper alloy pipe; and / or, One of the second outlet pipe and the fourth valve pipe is a flexible stainless steel pipe integrally formed, and the other is a copper pipe or a copper alloy pipe.

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