Outdoor heat exchanger, outdoor unit and heating and ventilation system

Abstract

This application discloses an outdoor heat exchanger, an outdoor unit, and a heating, ventilation, and air conditioning (HVAC) system. The outdoor heat exchanger includes a manifold, a distributor, and a heat exchange body located between them. The manifold includes a main pipe extending along the height direction and multiple branch pipes. Multiple connection holes are spaced apart along the height direction on the wall of the main pipe; the connection holes at the lowest height are first-type connection holes, and those above the lowest height are second-type connection holes. The distributor includes a distribution body and multiple branch pipes connected to the distribution body. The heat exchange body includes multiple heat exchange flow paths arranged sequentially along the height direction. The lowest heat exchange flow path is a defrosting flow path, which connects to the second-type connection holes via a corresponding branch pipe. This outdoor heat exchanger prevents accumulated liquid at the bottom of the manifold from being pushed into the heat exchange body, thus preventing deterioration of the refrigerant side heat exchange and improving the energy efficiency of the HVAC system.

Description

Technical Field

[0001] This article relates to refrigerant circulation technology, particularly an outdoor heat exchanger, outdoor unit, and HVAC system. Background Technology

[0002] When the outdoor unit operates in a low-temperature environment, the outdoor heat exchanger will experience frosting. This frosting reduces airflow, impairs heat transfer, and decreases heating capacity, necessitating defrosting to restore its performance. Reverse circulation defrosting is the most widely used method. When the outdoor heat exchanger's heating capacity decreases to a certain level, it switches from heating mode to cooling mode, allowing high-temperature refrigerant to flow through the heat exchanger for defrosting. Currently, the defrosting mode is activated based on the outlet temperature of the outdoor heat exchanger. Since the most severe frosting occurs at the bottom of the outdoor heat exchanger, a defrosting temperature sensor is placed in the heat exchange flow path at the bottom. The sensor's reading is used to activate / deactivate the defrosting mode. The energy efficiency of the HVAC system is related to the defrosting mode. Provided defrosting is complete, a shorter defrosting duration results in higher energy efficiency; more appropriate timing of defrosting mode activation also leads to higher energy efficiency.

[0003] However, there is liquid accumulation in the heat exchange path at the bottom of the current outdoor heat exchanger, which affects the heat exchange efficiency of the heat exchange path, further increases the duration of the defrosting mode, and affects the energy efficiency of the HVAC system. Summary of the Invention

[0004] When determining when to exit defrosting, the accumulated liquid in the refrigerant circulation loop will enter the heat exchange flow path at the bottom of the outdoor heat exchanger, which will worsen the heat exchange efficiency of the heat exchange flow path at the bottom of the outdoor heat exchanger. This will cause the temperature of the bottom heat exchange flow path to rise at a slower rate than other heat exchange flow paths, thus increasing the time that other heat exchange flow paths are in an ineffective defrosting state, increasing the duration of the defrosting mode, and reducing the energy efficiency of the HVAC system.

[0005] This disclosure provides an outdoor heat exchanger, an outdoor unit, and a heating, ventilation, and air conditioning (HVAC) system that prevents accumulated liquid at the lower end of the manifold of the outdoor heat exchanger from being pushed into the lowest heat exchange flow path of the heat exchange body, thereby avoiding deterioration of heat exchange on the refrigerant side of the heat exchange body and improving the capacity of the HVAC system.

[0006] This application provides an outdoor heat exchanger, including a collector, a distributor, and a heat exchange body located between the collector and the distributor. The heat exchange body includes multiple heat exchange flow paths. The supported plane of the heat exchange body is defined as a height reference plane, and the direction perpendicular to the height reference plane is defined as the height direction. The collector includes a main pipe extending along the height direction and multiple branch pipes. The pipe wall of the main pipe has multiple connection holes spaced apart along the height direction. The multiple connection holes are connected to the multiple branch pipes one-to-one. The multiple connection holes have a minimum height defined relative to the height reference plane. The connection holes located at the minimum height are defined as first-type connection holes. Connection holes higher than the minimum height are defined as first-type connection holes. The connection hole at the height is defined as a second type of connection hole; the distributor includes a distribution body and a plurality of branch pipes connected to the distribution body; the plurality of heat exchange flow paths are arranged sequentially in the height direction, and each heat exchange flow path has a first connector and a second connector at both ends, each first connector is connected to the corresponding branch pipe, and each second connector is connected to the corresponding branch pipe; the lowest heat exchange flow path among the plurality of heat exchange flow paths is defined as a defrosting flow path, the lowest first connector is the first connector of the defrosting flow path, and is connected to the second type of connection hole via the corresponding branch pipe, and a defrosting temperature sensor is thermally connected to the branch pipe connected to the second connector of the defrosting flow path.

[0007] This application also provides an outdoor unit, including the outdoor heat exchanger described in the above embodiments.

[0008] This application also provides a heating, ventilation, and air conditioning system, including the outdoor unit unit described in the above embodiments and an indoor unit unit connected to the outdoor unit unit.

[0009] Compared with related technologies, the outdoor heat exchanger, outdoor unit, and HVAC system provided in this application improve the energy efficiency of the HVAC system by connecting the lowest first connector of the lowest defrost flow path to a second type of connection hole higher than the first type of connection hole at the minimum height via a corresponding branch pipe. This ensures that the corresponding branch pipe extends upward from the manifold to the heat exchange body, preventing the accumulated liquid at the bottom of the main pipe from flowing into the lowest defrost flow path from the lowest first type of connection hole along the upward-extending branch pipe. This avoids deteriorating the heat exchange efficiency of the defrost flow path, shortens the duration of the defrost mode, and improves the energy efficiency of the HVAC system.

[0010] Other features and advantages of this application will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the application. Other advantages of this application can be realized and obtained by means of the embodiments described in the description and the accompanying drawings. Attached Figure Description

[0011] The accompanying drawings are used to provide an understanding of the technical solutions of this application and constitute a part of the specification. They are used together with the embodiments of this application to explain the technical solutions of this application and do not constitute a limitation on the technical solutions of this application.

[0012] Figure 1 This is a schematic diagram of a heating, ventilation, and air conditioning (HVAC) system according to an exemplary embodiment of this application, wherein the HVAC system is in defrosting mode; Figure 2 This is a schematic diagram of a heating, ventilation, and air conditioning (HVAC) system according to an exemplary embodiment of this application, wherein the HVAC system is in heating mode; Figure 3 This is a schematic diagram of the structure of an outdoor heat exchanger according to an exemplary embodiment of this application; Figure 4 This is a schematic diagram of the structure of a heat exchanger body according to an exemplary embodiment of this application; Figure 5 This is an exploded view of the heat exchanger body and chassis according to an exemplary embodiment of this application; Figure 5A for Figure 5 A magnified schematic diagram of part A in the diagram; Figure 5B for Figure 5 A magnified schematic diagram of part B in the diagram; Figure 6 for Figure 5 A top view of the chassis structure; Figure 7 For along Figure 6 A cross-sectional view taken by line CC in the middle; Figure 8 This is a three-dimensional structural schematic diagram of a current collector according to an exemplary embodiment of this application; Figure 9 This is an exploded structural diagram of the heat exchanger body and the collector according to an exemplary embodiment of this application; Figure 10 This is a schematic diagram of the connection structure between the heat exchange flow path and the collector according to an exemplary embodiment of this application; Figure 11 for Figure 10 A partial structural schematic diagram of the heat exchanger body and the collector is shown. Figure 12 This is a partial structural schematic diagram of the heat exchanger body and collector according to another exemplary embodiment of this application; Figure 13 This is a partial structural schematic diagram of the heat exchanger body and collector according to yet another exemplary embodiment of this application; Figure 14 This is a partial structural schematic diagram of the heat exchanger body and collector according to an exemplary embodiment of this application; Figure 15 This is a schematic diagram of the connection structure between the heat exchanger body and the collector according to another exemplary embodiment of this application; Figure 16 for Figure 15 A partial structural schematic diagram of the heat exchanger body and the collector is shown. Figure 17 This is a schematic diagram of the connection structure between the distributor and the heat exchanger body according to an exemplary embodiment of this application; Figure 18 This is a schematic diagram of the connection structure between the distributor and the heat exchanger body according to another exemplary embodiment of this application; Figure 19 for Figure 17 A cross-sectional view of the distributor in the diagram; Figure 20 This is a structural schematic diagram showing the placement of a temperature sensor according to an exemplary embodiment of this application; Figure 21 This is a schematic diagram illustrating the exit timing of a defrost mode according to an exemplary embodiment of this application; Figure 22 This is a schematic flowchart of a defrosting method according to an exemplary embodiment of this application; Figure 23 This is a schematic flowchart of a defrosting method according to another exemplary embodiment of this application; Figure 24 This is a schematic flowchart of a defrosting method according to yet another exemplary embodiment of this application; Figure 25 This is a block diagram of a control device for a heating, ventilation, and air conditioning system according to an exemplary embodiment of this application.

[0013] The attached diagram lists the components represented by each number as follows: RC - Heating, Ventilation and Air Conditioning System; 100 - Outdoor unit unit; 104 - Outdoor unit housing; 105 - Outdoor heat exchanger; 1-Collector; 10-Main tube; 10a-Connecting hole; 101-Type I connecting hole; 102-Type II connecting hole; 103-Transition joint; 11-Branch tube; 111-First shaft end; 112-Second shaft end; 12-Type I branch tube; 13-Type II branch tube; 14-Supported plane; 15-Branch joint; LQ-Liquid accumulation; 2-Heat exchanger body; 2a-Windward side; 2b-Leisure side; 20-Heat exchange flow path; 21-Defrosting flow path; 22-Temperature sensing flow path; 23-Secondary lower heat exchange flow path; 24-Heat exchange fins; 241-First side; 242-Second side; 25-U-shaped tube; 251-Straight tube section; 2511-Open end; 252-Bend section; 26-Bend joint; J1-First joint; J2-Second joint; G-Air inlet gap; 3-Distributor; 30-Diverter body; 301-Plug-in part; 302-Diverter hole; 303-Diverter channel; 304-Diverter cavity; 305-Throttle orifice; 31-Diverter pipe; 32-Combination pipe; W-Welding layer; 4-Chassis; 41-Support surface; 42-Drainage groove; 43-Drainage hole; 44-Flanged edge; 45-Drainage channel; 50 - Compressor; 501 - Discharge port; 502 - Inlet port; 40 - Reversing valve; D, S, E, C - Valve interfaces; 51 - Liquid-side switching valve; 52 - Gas-side switching valve; 60-Outdoor piping assembly; 61-Exhaust pipe; 62-Return pipe; 63-First piping; 64-Second piping; 65-Third piping; 66-Oil separator; 661-Return capillary tube; 67-Gas-liquid separator; 68-Check valve; 69-Outdoor expansion valve; T1 - Exhaust gas temperature sensor; T2 - Return gas temperature sensor; T3 - Defrosting temperature sensor; T3B - Intermediate temperature sensor; T4 - Outdoor ambient temperature sensor; 200-Indoor unit; 70-Indoor heat exchanger; 80-Indoor unit casing; 81-Indoor liquid pipe; 82-Indoor gas pipe; 83-Indoor expansion valve; 84-Liquid side connector; 85-Gas side connector; 86-Indoor fan; 300 - Liquid connection pipe; 400 - Gas connection pipe; 500 - Control device; 501 - Acquisition module; 502 - Judgment module; 503 - Drive module. Detailed Implementation

[0014] This application describes several embodiments, but these descriptions are exemplary and not limiting, and it will be apparent to those skilled in the art that many more embodiments and implementations are possible within the scope of the embodiments described herein. Although many possible combinations of features are shown in the drawings and discussed in the detailed description, many other combinations of the disclosed features are also possible. Unless specifically limited, any feature or element of any embodiment may be used in combination with, or may replace, any feature or element of any other embodiment.

[0015] This application includes and contemplates combinations of features and elements known to those skilled in the art. The embodiments, features, and elements disclosed in this application can also be combined with any conventional features or elements to form unique inventive solutions. Any feature or element of any embodiment can also be combined with features or elements from other inventive solutions to form another unique inventive solution. Therefore, it should be understood that any feature shown and / or discussed in this application can be implemented individually or in any suitable combination. Therefore, the embodiments are not limited except by the limitations imposed by the appended claims and their equivalents. Furthermore, various modifications and changes can be made within the scope of the appended claims.

[0016] Furthermore, in describing representative embodiments, the specification may have presented methods and / or processes as a specific sequence of steps. However, the method or process should not be limited to the specific order of steps described herein, to the extent that it does not depend on such a specific order. As will be understood by those skilled in the art, other sequences of steps are also possible. Therefore, the specific order of steps set forth in the specification should not be construed as a limitation of the claims. Moreover, the claims concerning the method and / or process should not be limited to the steps performed in the written order, and those skilled in the art will readily understand that these orders can be varied and still remain within the spirit and scope of the embodiments of this application.

[0017] In some cases, the outdoor unit operates in heating mode when the ambient temperature is low. This can lead to frost buildup on the outdoor heat exchanger. Frost reduces airflow and heat transfer, decreasing heating capacity and necessitating defrosting to restore the heat exchanger's performance. Reverse circulation defrosting is the most widely used method. When the outdoor heat exchanger's heating capacity decreases to a certain level, it switches from heating to cooling mode, allowing high-temperature refrigerant to flow through the heat exchanger for defrosting. Currently, defrosting mode activation is based on the outlet temperature of the outdoor heat exchanger. Since the most severe frost buildup occurs at the bottom of the outdoor heat exchanger, a defrosting temperature sensor is placed in the heat exchange flow path at the bottom. The sensor's reading is used to activate / deactivate defrosting mode. The energy efficiency of an HVAC system is related to the defrosting mode. Provided defrosting is complete, a shorter defrosting duration results in higher energy efficiency; more appropriate timing of defrosting mode activation also leads to higher energy efficiency.

[0018] However, there is liquid accumulation in the heat exchange path at the bottom of the current outdoor heat exchanger, which affects the heat exchange efficiency of the heat exchange path, further increases the duration of the defrosting mode, and reduces the energy efficiency of the HVAC system.

[0019] Currently, most HVAC systems rely on changes in defrost temperature sensor readings to determine whether to enter or exit reverse-cycle defrost mode. During reverse-cycle defrost, the heat exchange path at the bottom of the outdoor heat exchanger experiences the most severe frost buildup and liquid accumulation, resulting in the lowest outlet temperature. Therefore, the defrost temperature sensor is placed at the outlet of this heat exchange path. If the heat exchange path at the bottom of the outdoor heat exchanger has reached the conditions for exiting defrost mode, then the other heat exchange paths will also reach the conditions for exiting defrost mode.

[0020] The condition for entering the reverse defrosting process is that the defrosting temperature sensor reading is less than a preset temperature value A (A≤0℃), while the condition for exiting defrosting is generally that the defrosting temperature sensor reading is greater than a preset temperature value B (B>0℃). In the existing technology, when determining when to exit defrosting, the accumulated liquid at the bottom of the manifold flows into the heat exchange path at the bottom of the outdoor heat exchanger, deteriorating the heat exchange efficiency of this path. This causes the temperature of the heat exchange path at the bottom of the outdoor heat exchanger to rise to value B much later than other heat exchange paths, increasing the time that other paths are in an ineffective defrosting state, thus increasing the duration of the defrosting mode and reducing the energy efficiency of the HVAC system.

[0021] Therefore, such as Figures 1-20 As shown, this application embodiment provides an outdoor heat exchanger 105, an outdoor unit 100 including the outdoor heat exchanger, and a heating, ventilation, and air conditioning (RC) system including the outdoor unit 100.

[0022] The outdoor heat exchanger 105 provided in this application embodiment includes a collector 1, a distributor 3, and a heat exchange body 2 located between the collector 1 and the distributor 3. The heat exchange body 2 includes multiple heat exchange flow paths 20. The supported plane 14 of the heat exchange body 2 is defined as the height reference plane HP, and the direction perpendicular to the height reference plane HP is defined as the height direction.

[0023] The manifold 1 includes a main pipe 10 extending along the height direction and multiple branch pipes 11. The bottom end of the main pipe 10 along the height direction is closed, and the other end is a port end for connection to external piping. After the refrigerant enters the main pipe, liquid LQ is formed at the bottom of the main pipe. Liquid LQ is the lubricating oil of the compressor 50 or a mixture of liquid refrigerant and lubricating oil. The pipe wall of the main pipe 10 is provided with multiple connection holes 10a spaced apart along the height direction. The multiple connection holes 10a are connected to the multiple branch pipes 11 one by one. The multiple connection holes 10a are defined with a minimum height relative to the height reference plane. The connection holes 10a located at the minimum height are defined as first-type connection holes 101 (the connection holes located at the bottommost and closest to the height reference plane HP). The connection holes 10a above the minimum height are defined as second-type connection holes 102 (above the first-type connection holes 101). As the liquid LQ accumulates, the liquid level of the liquid LQ may exceed the height of the first-type connection holes 101 or may exceed the height of 1 to 2 second-type connection holes 102. Each branch pipe 11 includes a first shaft end 111 connected to the connection hole 10a and a second shaft end 112 connected to the heat exchange flow path 20. Among them, the branch pipe 11 connected to the first type of connection hole 101 is defined as the first type of branch pipe 12, and the branch pipe 11 connected to the second type of connection hole 102 is defined as the second type of branch pipe 13.

[0024] The distributor 3 includes a distribution body 30 and a plurality of branch pipes 31 connected to the distribution body 30.

[0025] Multiple heat exchange flow paths 20 are arranged sequentially in the height direction. Each heat exchange flow path 20 has a first connector J1 and a second connector J2 at both ends. Each first connector J1 is connected to the corresponding branch pipe 11 of the collector 1, and each second connector J2 is connected to the corresponding branch pipe 31.

[0026] Among the multiple heat exchange flow paths 20, the lowest heat exchange flow path 20 is defined as the defrosting flow path 21. The lowest first connector J1 is the first connector J1 of the defrosting flow path 21 (that is, at least one first connector J1 of the defrosting flow path 21 includes at least the lowest first connector J1), and is connected to the second type of connection hole 102 via the corresponding branch pipe 11. A defrosting temperature sensor T3 is thermally connected to the branch pipe 31 that is connected to the second connector J2 of the defrosting flow path 21.

[0027] The defrost temperature sensor T3 is positioned on the branch pipe 31 connected to the lowest heat exchange flow path 20 (defrost flow path 21) of the heat exchange body 2. However, this lowest defrost flow path 21 is not connected to the lowest first-type connection hole 101 of the collector 1, but rather to the second-type connection hole 102 above the first-type connection hole 101. This prevents the accumulated liquid LQ at the bottom of the collector 1 from flowing into the lowest defrost flow path 21 through the lowest first-type connection hole 101. Consequently, the temperature rise rate of the branch pipe 31 connected to the defrost flow path 21, as detected by the defrost temperature sensor T3, is accelerated, reducing defrosting time. The condition for exiting defrost mode is determined based on the temperature of the branch pipe 31 connected to the defrost flow path 21 detected by the defrost temperature sensor T3, reducing the time that other heat exchange flow paths 20 are in ineffective defrosting and improving the energy efficiency of the HVAC system.

[0028] In this embodiment, the accumulated liquid LQ will not enter the defrosting flow path 21, thus preventing the heat exchange efficiency of the defrosting flow path 21 from deteriorating. This avoids a slower temperature recovery in the defrosting flow path 21, reduces defrosting time, and improves the energy efficiency of the HVAC system. Furthermore, the difference between the temperature rise rate of the defrosting flow path 21 and the temperature rise rate of other heat exchange flow paths 20 is reduced, which can reduce the time that other heat exchange flow paths 20 are ineffective during defrosting, thereby reducing defrosting time and improving the energy efficiency of the HVAC system.

[0029] In one exemplary embodiment, such as Figure 12 and Figure 13 As shown, the number of the first connector J1 and the second connector J2 of the defrosting flow path 21 is one. The first connector J1 of the defrosting flow path 21 is the bottommost first connector J1, and the second connector J2 of the defrosting flow path 21 is the bottommost second connector J2.

[0030] The defrosting flow path 21 can be a common single-inlet and single-outlet flow path, which has a first connector J1 located at the bottom and a second connector J2 located at the bottom. The first connector J1 at the bottom is connected to the second type of connection hole 102 in the connection hole of the collector 1, which is not the bottommost type. This prevents the liquid LQ accumulated at the bottom of the collector 1 from flowing into the defrosting flow path 21 through the first type of connection hole 101 at the bottom. This reduces the difference in temperature rise rate between the defrosting flow path 21 and the other heat exchange flow path 20, thereby reducing defrosting time and improving the energy efficiency of the HVAC system.

[0031] In one exemplary embodiment, such as Figure 11 , Figure 14 and Figure 16 As shown, the defrosting flow path 21 has multiple first connectors J1, including the lowest first connector J1 and the next lowest first connector J1, and the next lowest first connector J1 is connected to the first type of connection hole 101 or the second type of connection hole 102.

[0032] The defrosting flow path 21 may have multiple first connectors J1, wherein the lowest first connector J1 is connected to the second type connection hole 102 (not the lowest connection hole) of the manifold 1, and the next lowest first connector J1 is connected to the first type connection hole 101 (the lowest connection hole) of the manifold 1, or connected to the second type connection hole 102 of the manifold 1, so that the liquid LQ accumulated at the bottom of the manifold 1 will not be pushed into the lowest defrosting flow path 21 through the first type connection hole 101, thereby reducing defrosting time and improving the energy efficiency of the HVAC system.

[0033] In some exemplary embodiments, such as Figures 11-16 As shown, the number of second connectors J2 in the defrosting flow path 21 is one, and the second connector J2 in the defrosting flow path 21 is the lowest second connector J2; or, the number of second connectors J2 in the defrosting flow path 21 is multiple, and includes at least the lowest second connector J2, and may also include the second connector J2 below it.

[0034] In some exemplary embodiments, such as Figure 17 As shown, the number of branch pipes 31 and the number of second connectors J2 are equal and they are connected one-to-one, which is beneficial for controlling the amount of refrigerant entering the heat exchange path 20 through the branch pipes 31; or, as Figure 18 As shown, the number of diverter pipes 31 is less than the number of second connectors J2, and at least one diverter pipe 31 is connected to multiple second connectors J2 at the same time, which helps to reduce the number of diverter pipes 31 and reduce the cost of distributor 3.

[0035] In some exemplary embodiments, such as Figure 11 , Figure 14 and Figure 16 As shown, the defrosting flow path 21 includes multiple branch paths and a main flow path formed by the convergence of the multiple branch paths. Each branch path corresponds to a multiple first connector J1, and the main flow path corresponds to a second connector J2. That is, the defrosting flow path 21 includes multiple first connectors J1 and one second connector J2. The multiple first connectors J1 of the multiple branch paths include at least the lowest first connector J1 and the next lowest first connector J1.

[0036] Furthermore, in an exemplary embodiment, such as Figure 11As shown, in the defrosting flow path 21, which includes multiple branch paths and a main flow path, the first connector J1 of each branch path is connected to a corresponding connection hole via a corresponding branch pipe 11 (i.e., the first connector J1 and the branch pipe 11 are in one-to-one correspondence and connection). The branch pipe 11 corresponding to the lowest first connector J1 is defined as the lowest branch pipe 11, and the branch pipe 11 corresponding to the next lowest first connector J1 is defined as the next lowest branch pipe 11. The lowest first connector J1 (the first connector J1 of the defrosting flow path 21) is connected to a second type connection hole 102 via the lowest branch pipe 11, and the next lowest first connector J1 (the first connector J1 of the defrosting flow path 21) is connected to a first type connection hole 101 via the next lowest branch pipe 11. The extension trajectories of the lowest branch pipe 11 and the next lowest branch pipe 11 intersect in the height direction. The next lowest branch pipe 11 is a first type branch pipe 12, and the other branch pipes 11 are second type branch pipes 13.

[0037] Furthermore, in another exemplary embodiment, such as Figure 14 As shown, in the defrosting flow path 21, which includes multiple branch paths and a main flow path, the first connector J1 of each branch path is connected to a corresponding connection hole via a corresponding branch pipe 11 (that is, the first connector J1 and the branch pipe 11 correspond one-to-one and are connected). The branch pipe 11 corresponding to the lowest first connector J1 is defined as the lowest branch pipe 11, and the branch pipe 11 corresponding to the next lowest first connector J1 is defined as the next lowest branch pipe 11. The lowest first connector J1 (the first connector J1 of defrosting flow path 21) is connected to a second type connection hole 102 via the lowest branch pipe 11. The next lowest first connector J1 (the first connector J1 of defrosting flow path 21) is connected to another second type connection hole 102 via the next lowest branch pipe 11. The extension trajectory of the lowest branch pipe 11 is lower than that of the next lowest branch pipe 11. The heat exchange flow path 20 above the defrosting flow path 21 is defined as the next lowest heat exchange flow path 23. The first connector J1 of the next lowest heat exchange flow path 23 is connected to a first type connection hole 101 via a corresponding branch pipe 11. The extension trajectory of the branch pipe 11 corresponding to the first connector J1 of the next lowest heat exchange flow path 23 intersects the extension trajectories of the lowest and next lowest branch pipes in the height direction. The branch pipe 11 corresponding to the first connector J1 of the next lowest heat exchange flow path 23 is a first type branch pipe 12, and the other branch pipes 11 are second type branch pipes 13.

[0038] In this embodiment, the first type of branch pipe 12 is not connected to the lowest first connector J1 and the next lowest first connector J1, but is connected to the first connector J1 of the next lowest heat exchange flow path 23 (other first connectors J1 above the next lowest first connector J1), so that the second shaft end 112 of the first type of branch pipe 12 is higher and has a greater height difference with the first shaft end 111, which can better prevent the liquid LQ at the bottom of the collector 1 from flowing to the second shaft end 112 of the first type of branch pipe 12 under the action of gravity, and prevent the liquid LQ from entering the heat exchange flow path 20 of the heat exchange body 2.

[0039] In yet another exemplary embodiment, such as Figure 15 and Figure 16 As shown, in the defrosting flow path 21, which includes multiple branch paths and a main flow path, multiple first connectors J1 of the multiple branch paths are connected to a second type connection hole 102 via a corresponding branch pipe 11 (second type branch pipe 13). (That is, multiple branch paths correspond to and are connected to a branch pipe 11). The first shaft end 111 of the corresponding branch pipe 11 is constructed as a single tube and inserted into the second type connection hole 102. The second shaft end 112 of the corresponding branch pipe 11 is constructed as a multi-branch pipe, forming multiple branch connectors 15. The multiple branch connectors 15 are respectively connected to the multiple first connectors J1 of the multiple branch paths. The corresponding branch pipe 11 extends from the first shaft end 111 from high to low to the second shaft end 112. In this way, the number of branch pipes 11 can be reduced, thus reducing costs.

[0040] In some exemplary embodiments, such as Figure 15 and Figure 16 As shown, each heat exchange flow path 20 includes multiple branch paths and a main flow path formed by the convergence of multiple branch paths. Each branch path corresponds to a multiple first connector J1, and each main flow path corresponds to a second connector J2. The first connector J1 of each branch path is connected to a corresponding connection hole via a corresponding branch pipe 11 (i.e., the branch path and the branch pipe 11 are connected one-to-one). Alternatively, the multiple first connectors J1 of the multiple branch paths of each heat exchange flow path 20 are connected to a corresponding connection hole via a corresponding branch pipe 11 (i.e., the multiple branch paths and the branch pipe 11 are connected).

[0041] In one exemplary embodiment, such as Figure 11 As shown, the lowermost first connector J1 is connected to the first type of connection hole 101 via a corresponding branch pipe 11. The height of the lowermost first connector J1 is greater than the height of the first type of connection hole 101. The branch pipe 11 corresponding to the lowermost first connector J1 extends from the lowermost first connector J1 from high to low to the first type of connection hole 101. Among them, the branch pipe 11 corresponding to the lowermost first connector J1 is the first type of branch pipe 12.

[0042] The first connector J1 at the next lower level is connected to the first connection hole 101 via the first type of branch pipe 12, and the height of the first connector J1 at the next lower level is greater than the height of the first connection hole 101. This can prevent the liquid LQ at the bottom of the collector 1 from flowing through the first connection hole 101 to the first connector J1 and then into the heat exchange flow path 20, thus avoiding the liquid LQ affecting the heat exchange capacity of the heat exchange body 2.

[0043] In some exemplary embodiments, the outdoor heat exchanger 105 operates in a defrost mode. The triggering condition for the defrost mode includes: the detected value of the defrost temperature sensor T3 is lower than a first preset value. The exit condition for the defrost mode includes at least: the detected value of the defrost temperature sensor T3 is higher than a second preset value. The first preset value is less than or equal to 0°C, and the second preset value is greater than 0°C.

[0044] In this exemplary embodiment, each heat exchange flow path 20 includes a plurality of U-shaped tubes 25 and at least one elbow joint 26 connecting the plurality of U-shaped tubes 25 sequentially. Each U-shaped tube 25 includes two straight tube sections 251 and an elbow section 252 integrally connecting the two straight tube sections 251. The straight tube section 251 includes an open end 2511 away from the elbow section 252 and a main pipe section located between the open end 2511 and the elbow section 252. The outer diameter of the main pipe section is any one of 5mm, 7mm, and 9.52mm. Of course, the outer diameter of the main pipe section is not limited to the above values ​​and can be adjusted according to actual needs.

[0045] It should be understood that sequential connection is not the same as series connection. Sequential connection can be multiple U-tubes 25 connected in series in sequence, or it can be two or more U-tubes 25 in the same sequence and connected in parallel, and then connected in series with other U-tubes 25.

[0046] In this heat exchange flow path 20 connected to the first type of branch pipe 12 of the collector 1, at least one straight pipe section 251 has a height higher than the height of the first type of connection hole 101 of the collector 1, thus achieving a height lower than at least a portion of the height of the heat exchange flow path 20 connected to the first type of branch pipe 12 of the collector 1. Furthermore, at least half of the straight pipe sections 251 connected to the first type of branch pipe 12 of the collector 1 can be set to a height higher than the height of the first type of connection hole 101 of the collector 1. Even further, all the straight pipe sections 251 connected to the first type of branch pipe 12 of the collector 1 have a height higher than the height of the first type of connection hole 101 of the collector 1.

[0047] In the solution of this application embodiment, since the liquid LQ at the bottom of the collector 1 cannot enter the lowest defrosting flow path 21, the time point for entering and exiting the defrosting mode can be determined more accurately by the detection value of the defrosting temperature sensor T3. This avoids the problem of severe frost formation on the heat exchange body 2 caused by entering the defrosting mode too late, and avoids the time increase of other flow paths outside the defrosting flow path 21 being in an ineffective defrosting state caused by exiting the defrosting mode too late, thereby improving the energy efficiency of the HVAC system.

[0048] In another exemplary embodiment, the plurality of heat exchange flow paths 20 further includes a temperature sensing flow path 22, which is disposed above the defrosting flow path 21. An intermediate temperature sensor T3B is provided on the temperature sensing flow path 22, positioned between the first connector J1 and the second connector J2. The intermediate temperature sensor T3B can be disposed on any one of the plurality of bends 26 between the first connector J1 and the second connector J2, or on any one of the plurality of bends 252 between the first connector J1 and the second connector J2. The temperature sensing flow path 22 can be the uppermost heat exchange flow path 20, or it can be any of the heat exchange flow paths 20 other than the defrosting flow path 21 and the uppermost heat exchange flow path 20.

[0049] In this exemplary embodiment, the outdoor heat exchanger 105 operates in a defrost mode. The defrost mode is triggered when the minimum value between the defrost temperature sensor T3 and the intermediate temperature sensor T3B is lower than a first preset value. The defrost mode is deactivated when the maximum value between the defrost temperature sensor T3 and the intermediate temperature sensor T3B is higher than a second preset value. The first preset value is less than the second preset value. The first preset value can be set to be less than 0°C, and the second preset value can be set to be greater than 0°C.

[0050] In this embodiment, the defrosting mode is triggered if the detection value of either the defrosting temperature sensor T3 or the intermediate temperature sensor T3B is lower than the first preset value; the defrosting mode is exited if the detection value of either the defrosting temperature sensor T3 or the intermediate temperature sensor T3B is higher than the second preset value.

[0051] In this exemplary embodiment, each heat exchange flow path 20 includes a plurality of U-shaped tubes 25 and at least one elbow joint 26 that connects the plurality of U-shaped tubes 25 in sequence. Each U-shaped tube 25 includes two straight tube sections 251 and an elbow section 252 integrally connected to the two straight tube sections 251. An intermediate temperature sensor T3B is thermally connected to the elbow section 252 of the temperature sensing flow path 22, or the intermediate temperature sensor T3B is thermally connected to the elbow joint 26 of the temperature sensing flow path 22.

[0052] The intermediate temperature sensor T3B can be arranged at the elbow part 252 or the elbow joint 26 of the temperature sensing flow path 22. The installation position can be flexibly selected according to needs, which is convenient for the installation and fixation of the intermediate temperature sensor T3B.

[0053] Furthermore, in this exemplary embodiment, the straight pipe part 251 includes an open end 2511 at one end far from the elbow part 252 and a main pipe section located between the open end 2511 and the elbow part 252. The outer diameter of the main pipe section is 5 mm.

[0054] The outer diameter of the main pipe section of the heat exchange flow path 20 is 5 mm. For such a small-diameter heat exchange flow path 20, the pressure drop of the refrigerant becomes larger when passing through the heat exchange flow path 20. For the outdoor heat exchanger 105 with a small diameter (the outer diameter of the main pipe section of the heat exchange flow path 20 is 5 mm) and the outdoor heat exchanger 105 with a large diameter (the outer diameter of the main pipe section of the heat exchange flow path 20 > 5 mm) under the same conditions: when the detected value of the defrosting temperature sensor T3 < A (the condition for triggering the frosting mode), the overall temperature of the outdoor heat exchanger 105 with a small diameter (5 mm) will be lower than the overall temperature of the outdoor heat exchanger 105 with a large diameter (> 5 mm). This means that when the frosting mode is triggered, the frosting degree of the outdoor heat exchanger 105 with a small diameter (5 mm) is more serious than that of the outdoor heat exchanger 105 with a large diameter (> 5 mm), and the time point for the outdoor heat exchanger 105 with a small diameter (5 mm) to enter the defrosting mode is relatively delayed. By combining the detected values of the defrosting temperature sensor T3 and the intermediate temperature sensor T3B to determine the time point for entering the defrosting mode, the outdoor heat exchanger 105 can enter the defrosting mode at a more appropriate time point, avoiding the problem of serious frosting of the heat exchange main body 2 caused by entering the defrosting mode too late, and reducing the time for the outdoor heat exchanger 105 to be in the low-capacity state of serious frosting; by combining the detected values of the defrosting temperature sensor T3 and the intermediate temperature sensor T3B to determine the time point for exiting the defrosting mode, the outdoor heat exchanger 105 can exit the defrosting mode at a more appropriate time point, avoiding the increase in the time for other flow paths outside the defrosting flow path 21 to be in the ineffective defrosting state caused by exiting the defrosting mode too late, and improving the energy efficiency of the HVAC system.

[0055] Certainly, for the small-diameter heat exchange flow path 20, the outer diameter of its main pipe section is not limited to 5 mm and can also be adjusted according to actual needs.

[0056] In some exemplary embodiments, the multiple branch pipes 11 of the collector 1 are connected to the multiple connection holes 10a one by one. Among them, the height of the first type of connection hole 101 is configured to be lower than the height of at least a part of the heat exchange flow path 20 connected to the first type of branch pipe 12.

[0057] By configuring the height of the first type of connection hole 101 at the minimum height in the manifold 1 to be lower than the height of at least a portion of the heat exchange flow path 20 connected to the first type of branch pipe 12, the accumulated liquid LQ at the bottom of the manifold 1 cannot flow into the heat exchange flow path 20, which is higher than the first type of connection hole 101, through the first type of connection hole 101 and the first type of branch pipe 12. This avoids deteriorating the heat exchange on the refrigerant side of the heat exchange body 2 when the HVAC system is defrosting, so that the HVAC system can exit the reverse circulation defrosting process in a timely manner, shortening the time that the heat exchange flow path 20 is in an ineffective defrosting state, thereby improving the energy efficiency of the HVAC system.

[0058] In one exemplary embodiment, the heights of the first shaft end 111 and the second shaft end 112 of the first type of branch pipe 12 are equal; or, the height of the second shaft end 112 of the first type of branch pipe 12 is higher than the height of the first shaft end 111 of the first type of branch pipe 12.

[0059] The heights of the first shaft end 111 and the second shaft end 112 of the first type of branch pipe 12 are equal, that is, the first type of branch pipe 12 can be a horizontal straight pipe. In this case, the height of the first type of branch pipe 12 is equal to the height of the first type of connection hole 101, and the height of the first connector J corresponding to the first type of connection hole 101 is equal to the height of the first type of connection hole 101. At least a portion of the heat exchange flow path 20 connected to the second shaft end 112 of the first type of branch pipe 12 is higher than the height of the first type of branch pipe 12. Of course, the height of the second shaft end 112 of the first type of branch pipe 12 can also be set to be higher than the height of its first shaft end 111, that is, the first type of branch pipe 12 can be a bent pipe, to ensure that the height of the first type of connection hole 101 connected to the first shaft end 111 of the first type of branch pipe 12 is lower than the height of at least a portion of the heat exchange flow path 20 connected to the second shaft end 112 of the first type of branch pipe 12. The height of the second shaft end 112 of the first type of branch pipe 12 is higher than the height of the first shaft end 111 of the first type of branch pipe 12. That is, from the first shaft end 111 toward the second shaft end 112, the first type of branch pipe 12 extends upward as a whole, which can effectively prevent the accumulated liquid LQ at the lower end of the collector 1 from being pushed into the heat exchange flow path 20 of the heat exchange body 2 through the first type of connection hole 101 and the first type of branch pipe 12.

[0060] Both of the above-mentioned configuration methods of the first type of branch pipe 12 can improve the reverse circulation defrosting process of the HVAC system and improve the energy efficiency of the HVAC system.

[0061] In one exemplary embodiment, the height of the second shaft end 112 of the first type of branch pipe 12 is higher than the height of the second shaft end 112 of at least one second type of branch pipe 13.

[0062] Multiple heat exchange flow paths 20 of the heat exchange body 2 are arranged sequentially in the height direction, and the lowest heat exchange flow path 20 is defined as the defrosting flow path 21. Each heat exchange flow path 20 has a first connector J1 and a second connector J2 at both ends. The first connector J1 is connected to the second shaft end 112 of the corresponding branch pipe 11 in the collector 1, and the second connector J2 is connected to the corresponding branch pipe 31 in the distributor 3. The defrosting flow path 21 can have only one first connector J1, and the first connector J1 of the defrosting flow path 21 is the lowest first connector J1. Since the height of the second shaft end 112 of the first type of branch pipe 12 is higher than the height of the second shaft end 112 of at least one second type of branch pipe 13, the heat exchange flow path 20 connected to the first type of branch pipe 12 is not the lowest defrosting flow path 21, but rather another heat exchange flow path 20 above the defrosting flow path 21; one of the second type of branch pipes 13 of the collector 1 is connected to the lowest defrosting flow path 21. This also helps to ensure that the height of the first type of connection hole 101 of the manifold 1 is lower than at least a part of the height of the heat exchange flow path 20 connected to the first type of branch pipe 12, thus preventing the liquid LQ in the manifold from entering the defrosting flow path, thereby improving the reverse circulation defrosting process of the HVAC system and improving the energy efficiency of the HVAC system.

[0063] Alternatively, the number of first connectors J1 in the defrosting flow path 21 may be multiple, such as: the defrosting flow path 21 includes multiple branch paths and a main flow path formed by the convergence of multiple branch paths, each branch path has a corresponding first connector J1, and the main flow path has a corresponding second connector J2. The multiple first connectors J1 of the multiple branch paths (i.e., the first connectors J1 of the defrosting flow path 21) include at least the lowest first connector J1 and the next lowest first connector J1. Since the height of the second shaft end 112 of the first type of branch pipe 12 is higher than the height of the second shaft end 112 of at least one second type of branch pipe 13, the heat exchange flow path 20 connected to the first type of branch pipe 12 is not the lowest defrosting flow path 21, or the first type of branch pipe 12 is connected to other first joints J1 of the defrosting flow path 21 except the lowest first joint J1 (such as the second lowest first joint J1). This also helps to ensure that the height of the first type of connection hole 101 of the collector 1 is lower than the height of at least a part of the heat exchange flow path 20 connected to the first type of branch pipe 12, thereby improving the reverse circulation defrosting process of the HVAC system and improving the energy efficiency of the HVAC system.

[0064] In one exemplary embodiment, the first type of branch pipe 12 extends from the first shaft end 111 from low to high to the second shaft end 112, that is, the first type of branch pipe 12 may be a bend; or, the first type of branch pipe 12 extends from the first shaft end 111 along a horizontal direction perpendicular to the height direction to the second shaft end 112, that is, the first type of branch pipe 12 may be a horizontal straight pipe. A second type of branch pipe 13 extends from the first shaft end 111 from high to low to the second shaft end 112, that is, the second type of branch pipe 13 may be a bend, and the height of the second shaft end 112 of the second type of branch pipe 13 is lower than the height of the second shaft end 112 of the first type of branch pipe 12, so that the extension trajectory of the second type of branch pipe 13 and the extension trajectory of the first type of branch pipe 12 intersect in the height direction.

[0065] In some exemplary embodiments, such as Figure 11 As shown, multiple second-type connection holes 102 are provided, including a lowermost second-type connection hole 102 (a second-type connection hole 102 located above and adjacent to the first-type connection hole 101) and a next-lower second-type connection hole 102 (a second-type connection hole 102 located above and adjacent to the lowermost second-type connection hole 102). A second-type branch pipe 13 connected to the lowermost second-type connection hole 102 extends from the first shaft end 111 to the second shaft end 112 from low to high, and the height of the second shaft end 112 of the second-type branch pipe 13 connected to the lowermost second-type connection hole 102 is higher than the height of the second shaft end 112 of the first-type branch pipe 12; and the next-lower second-type connection hole 102... The second type of branch pipe 13 connected to the first shaft end 111 extends from high to low to the second shaft end 112, and the height of the second shaft end 112 of the second type of branch pipe 13 connected to the second type of connection hole 102 below it is lower than the height of the second shaft end 112 of the first type of branch pipe 12; wherein, the extension trajectory of the second type of branch pipe 13 connected to the second type of connection hole 102 below it is set to intersect the extension trajectory of the first type of branch pipe 12 in the height direction, and the extension trajectory of the second type of branch pipe 13 connected to the second type of connection hole 102 below it is also set to intersect the extension trajectory of the second type of branch pipe 13 connected to the lowest second type of connection hole 102 in the height direction.

[0066] The heights of the first type of connection hole 101, the lowest second type of connection hole 102, and the next lowest second type of connection hole 102 increase sequentially. The heights of the second shaft end 112 of the second type of branch pipe 13 connected to the next lowest second type of connection hole 102, the second shaft end 112 of the first type of branch pipe 12 connected to the first type of connection hole 101, and the second shaft end 112 of the second type of branch pipe 13 connected to the lowest second type of connection hole 102 also increase sequentially. The second type of branch pipe 13 connected to the next lowest second type of connection hole 102 can be connected to the lowest first connector J1 of the defrosting flow path 21. The first type of branch pipe 12 and the second type of branch pipe 13 connected to the lowest second type of connection hole 102 can be connected to other heat exchange flow paths 20 above the defrosting flow path 21, or to other first connectors J1 of the defrosting flow path 21 except for the lowest first connector J1.

[0067] In other exemplary embodiments, such as Figures 12-16 As shown, there are multiple second-type connection holes 102, including the lowest second-type connection hole 102 and the next lowest second-type connection hole 102. The second-type branch pipe 13 connected to the lowest second-type connection hole 102 extends from the first shaft end 111 from high to low to the second shaft end 112. The height of the second shaft end 112 of the second-type branch pipe 13 connected to the lowest second-type connection hole 102 is lower than the height of the second shaft end 112 of the first-type branch pipe 12. The extension trajectory of the first-type branch pipe 12 is set to intersect the extension trajectory of the second-type branch pipe 13 connected to the lowest second-type connection hole 102 in the height direction.

[0068] The height of the first type of connection hole 101 is lower than the height of the lowest second type of connection hole 102. However, the height of the second shaft end 112 of the second type of branch pipe 13 connected to the first type of connection hole 101 is higher than the height of the second shaft end 112 of the second type of branch pipe 13 connected to the lowest second type of connection hole 102. The second type of branch pipe 13 connected to the lowest second type of connection hole 102 can be connected to the first connector J1 of the defrosting flow path 21. The first type of branch pipe 12 can be connected to other heat exchange flow paths 20 above the defrosting flow path 21, or to other first connectors J1 of the defrosting flow path 21 except for the lowest first connector J1.

[0069] In one exemplary embodiment, such as Figure 15 and Figure 16 As shown, along the upward direction, above the lowest second type connection hole 102, there are also multiple second type connection holes 102. The height of the first shaft end 111 of the multiple second type branch pipes 13 that are connected to the multiple second type connection holes 102 above the lowest second type connection hole 102 increases sequentially, and the height of the second shaft end 112 also increases sequentially.

[0070] The heights of the first shaft ends 111 and the second shaft ends 112 of the multiple second-type branch pipes 13 connected to the multiple second-type connection holes 102 above the lowest second-type connection hole 102 increase sequentially. This means that the extension trajectories of the multiple second-type branch pipes 13 connected to the multiple second-type connection holes 102 above the lowest second-type connection hole 102 do not intersect in the height direction. Therefore, along the bottom-up direction, the multiple second-type branch pipes 13 connected to the multiple second-type connection holes 102 above the lowest second-type connection hole 102 can be connected to multiple heat exchange flow paths 20 with sequentially increasing heights.

[0071] In another exemplary embodiment, such as Figures 12-14 As shown, the second type branch pipe 13, which is connected to the second type connection hole 102 below, extends from the first shaft end 111 to the second shaft end 112 from high to low. The height of the second shaft end 112 of the second type branch pipe 13 connected to the second type connection hole 102 below is lower than the height of the second shaft end 112 of the first type branch pipe 12, and higher than the height of the second shaft end 112 of the second type branch pipe 13 connected to the lowest second type connection hole 102. The extension trajectory of the first type branch pipe 12 is set to intersect the extension trajectory of the second type branch pipe 13 connected to the second type connection hole 102 below in the height direction.

[0072] Furthermore, in this exemplary embodiment, along the upward direction, a plurality of second type connection holes 102 are provided above the second type connection hole 102 at the next lower level. The height of the first shaft end 111 of the plurality of second type branch pipes 13 that are connected to the plurality of second type connection holes 102 above the second type connection hole 102 at the next lower level increases sequentially, and the height of the second shaft end 112 also increases sequentially.

[0073] The heights of the first type of connection hole 101, the lowest second type of connection hole 102, and the next lowest second type of connection hole 102 increase sequentially. The heights of the second shaft end 112 of the second type of branch pipe 13 connected to the lowest second type of connection hole 102, the second shaft end 112 of the second type of branch pipe 13 connected to the next lowest second type of connection hole 102, and the second shaft end 112 of the first type of branch pipe 12 connected to the first type of connection hole 101 also increase sequentially. The second type of branch pipe 13 connected to the lowest second type of connection hole 102 can be connected to the lowest first connector J1 of the defrosting flow path 21. The second type of branch pipe 13 connected to the lowest second type of connection hole 102 and the first type of branch pipe 12 can be connected to other heat exchange flow paths 20 above the defrosting flow path 21, or to other first connectors J1 of the defrosting flow path 21 except for the lowest first connector J1.

[0074] The heights of the first shaft ends 111 and the second shaft ends 112 of the multiple second-type branch pipes 13 connected to the multiple second-type connection holes 102 above the next lower second-type connection hole 102 increase sequentially. This means that the extension trajectories of the multiple second-type branch pipes 13 connected to the multiple second-type connection holes 102 above the next lower second-type connection hole 102 do not intersect in the height direction. Therefore, along the bottom-up direction, the multiple second-type branch pipes 13 connected to the multiple second-type connection holes 102 above the next lower second-type connection hole 102 can be connected to multiple heat exchange flow paths 20 with sequentially increasing heights.

[0075] In an exemplary embodiment, the main tube 10 of the collector 1 can be a flute-shaped tube, and the connection hole on the main tube 10 can be a flanged hole.

[0076] In one exemplary embodiment, such as Figure 8 and Figure 9 As shown, the main body tube 10 of the collector 1 can be made of stainless steel. One axial end of the main body tube 10 (e.g., the lower end of the main body tube 10) is closed by a cap, and the other end is provided with a transition joint 103. The material of the transition joint 103 is the same as the material of the connection part of the external piping to be connected, for example: Figure 1 and Figure 2 As shown, the external piping connected to it is the first piping 63, which is connected to the reversing valve 40 of the HVAC system. The first piping 63 is made entirely of copper, and one end of the first piping 63 is the connecting part. The transition joint 103 is made of copper (i.e., the transition joint 103 can be a copper sleeve) and is welded to one end of the first piping 63; alternatively, the first piping 63 is made of stainless steel, and one end of it is also fitted with another transition joint, which is the connecting part of the first piping 63. The transition joint of the first piping 63 and the transition joint 103 of the main pipe 10 of the manifold 1 are both made of copper and are welded together. The multiple connection holes 10a can be flanged holes provided on the pipe wall of the main pipe 10. The branch pipes 11 can be made of copper, aluminum, or steel: copper branch pipes 11 are connected to heat exchange flow paths 20 made of copper; aluminum branch pipes 11 are connected to heat exchange flow paths 20 made of aluminum; the ends of steel branch pipes 11 can be connected to transition joints. When the heat exchange flow path 20 is made of copper, the transition joint at the end of the branch pipe 11 is made of copper; when the heat exchange flow path 20 is made of aluminum, the transition joint at the end of the branch pipe 11 is made of aluminum.

[0077] This application provides an outdoor unit, including the outdoor heat exchanger described in any of the above embodiments.

[0078] This application provides a heating, ventilation, and air conditioning system, including an outdoor unit unit as described in any of the above embodiments and an indoor unit unit connected to the outdoor unit unit.

[0079] The present application will now be described with reference to the accompanying drawings.

[0080] This application provides a heating, ventilation, and air conditioning system, such as... Figure 1 and Figure 2 As shown, the system includes: an outdoor unit 100, an indoor unit 200, a liquid connection pipe 300 and a gas connection pipe 400 connecting the outdoor unit 100 and the indoor unit 200, and a control device 500 for controlling the operation of components in the indoor unit 200 and the outdoor unit 100. The outdoor unit 100, the indoor unit 200, the liquid connection pipe 300, and the gas connection pipe 400 form a refrigerant circulation loop.

[0081] The indoor unit unit 200 includes an indoor heat exchanger 70, an indoor unit housing 80, an indoor liquid pipe 81, an indoor gas pipe 82, an indoor expansion valve 83, a liquid-side connector 84, a gas-side connector 85, and an indoor fan 86, etc. The outdoor unit unit 100 includes an outdoor heat exchanger 105, a compressor 50, a reversing valve 40, a liquid-side switching valve 51, a gas-side switching valve 52, an outdoor piping assembly 60, an oil separator 66, a gas-liquid separator 67, a one-way valve 68, and an outdoor expansion valve 69, etc. The outdoor piping assembly 60 includes an exhaust pipe 61 connected to the exhaust port 501 of the compressor 50, a return pipe 62 connected to the suction port 502 of the compressor 50, a first piping 63, a second piping 64, and a third piping 65. The oil separator 66 is disposed in the exhaust pipe 61 and also includes a return oil capillary tube 661 for connecting to the suction port 502 of the compressor 50. The HVAC system RC also includes an exhaust temperature sensor T1 located on the exhaust port 501 side of the compressor 50, a return air temperature sensor T2 located on the suction port 502 side of the compressor 50, and an ambient temperature sensor T4 located near the outdoor heat exchanger 105. The exhaust temperature sensor T1 can be installed on the exhaust pipe 61, the return air temperature sensor T2 can be installed on the return air pipe 62, and the ambient temperature sensor T4 can be used to detect the outdoor ambient temperature. The connection states of the reversing valve 40 include: a first connection state (corresponding to defrosting mode and cooling mode) and a second connection state (corresponding to heating mode).

[0082] Please see Figure 1The reversing valve 40 is in a first connection state, meaning that valve ports D and C of the reversing valve are connected to establish a flow path between the discharge port 501 of the compressor 50 and the outdoor heat exchanger 105, and valve ports E and S are connected to establish a flow path between the indoor heat exchanger 70 and the suction port 502 of the compressor 50. The second connection state means that valve ports E and D of the reversing valve are connected to establish a flow path between the indoor heat exchanger 70 and the discharge port 501 of the compressor 50, and valve ports C and S are connected to establish a flow path between the outdoor heat exchanger 105 and the suction port 502 of the compressor 50. The outdoor unit 100 is located in the outdoor environment and, as a core component of the refrigerant circuit, enables efficient heat exchange between the refrigerant and the environment (heat dissipation in cooling mode and heat absorption in heating mode). The indoor unit 200 is located in the indoor space. Through the cooperation of the indoor heat exchanger 70 and the indoor fan 86, it transfers the heat absorbed or released by the refrigerant to the indoor air, thereby regulating the room temperature. The compressor 50 drives the refrigerant circulation, the outdoor expansion valve 69 precisely regulates the refrigerant flow, the outdoor fan enhances the heat exchange efficiency between the outdoor heat exchanger 105 and the ambient air, and the gas-liquid separator 67 performs gas-liquid separation to ensure stable system operation. The HVAC system RC is dynamically coordinated by the control device 500 to achieve switching between cooling / heating modes and energy efficiency optimization.

[0083] The reversing valve 40 is the core control component of the HVAC system for switching between cooling and heating modes. The specific control process is as follows: 1. Cooling mode (corresponding to the first connection state in the above embodiments): like Figure 1 As shown, valve ports D-C and E-S of the reversing valve 40 are open. The refrigerant flow path is: compressor 50 → oil separator 66 → outdoor heat exchanger 105 → indoor heat exchanger 70 → gas-liquid separator 67 → compressor 50. At this time, the refrigerant absorbs heat (evaporates) in the indoor heat exchanger 70 and releases heat (condenses) in the outdoor heat exchanger 105.

[0084] 2. Heating mode (corresponding to the second connection state in the above embodiments): like Figure 2 As shown, valve ports D-E and C-S of the reversing valve 40 are open. The refrigerant flow path is: compressor 50 → oil separator 66 → indoor heat exchanger 70 → outdoor heat exchanger 105 → gas-liquid separator 67 → compressor 50. At this time, the refrigerant releases heat (condenses) in the indoor heat exchanger 70 and absorbs heat (evaporates) in the outdoor heat exchanger 105.

[0085] 3. Defrosting mode (In heating mode, if defrosting is required, switch from the second connection state to the first connection state) like Figure 1 As shown, valve port D-valve port C and valve port E-valve port S of reversing valve 40 are open. At this time, the refrigerant flow direction is the same as in the cooling mode, but the system is in the defrosting stage. The high-temperature and high-pressure refrigerant flows from compressor 50 through valve port D-valve port C to outdoor heat exchanger 105 (which becomes a condenser), releasing heat and melting the frost layer.

[0086] The HVAC system (RC) is equipped with a defrosting mode. In defrosting mode, the outdoor fan and indoor fan 86 stop working, and the refrigerant circulation path is as follows: compressor 50, outdoor heat exchanger 105, outdoor expansion valve 69, indoor heat exchanger 70, gas-liquid separator 67, and compressor 50. Specifically, the reversing valve 40 switches from the second connection state to the first connection state. The compressor 50 compresses the low-temperature, low-pressure gaseous refrigerant into a high-temperature, high-pressure gaseous refrigerant. The high-temperature, high-pressure gaseous refrigerant passes through the reversing valve 40 and enters the outdoor heat exchanger 105, where it condenses and releases heat to become high-pressure liquid refrigerant, melting the frost layer during this process. The high-pressure liquid refrigerant then passes through the outdoor expansion valve 69 to reduce its pressure, becoming low-pressure liquid refrigerant. This low-pressure liquid refrigerant enters the indoor heat exchanger 70, absorbs heat, and evaporates to become low-temperature, low-pressure gaseous refrigerant. After passing through the gas-liquid separator 67 to separate the liquid refrigerant, the gaseous refrigerant is reused by the compressor 50, continuing the circulation.

[0087] In defrost mode, the surface temperature of the outdoor heat exchanger 105 can rise from below 0°C to approximately 6°C, ensuring complete melting of the frost layer. High-pressure liquid refrigerant is throttled and depressurized through the outdoor expansion valve 69, transforming into low-pressure liquid refrigerant with a temperature drop to approximately 5-10°C. The outdoor expansion valve 69 dynamically adjusts its opening according to system requirements (such as refrigerant flow rate and pressure) to ensure appropriate refrigerant flow during defrosting, preventing decreased defrosting efficiency or abnormal system pressure due to insufficient or excessive flow. The low-pressure liquid refrigerant enters the indoor heat exchanger 70 (acting as an evaporator at this time), where it absorbs heat and evaporates, becoming a low-temperature, low-pressure gaseous refrigerant with an evaporation temperature of approximately 0-5°C. Although the indoor heat exchanger 70 absorbs heat during this stage, the indoor fan 86 has stopped operating, therefore it does not affect the indoor environment. In the gas-liquid separator 67, the low-temperature, low-pressure gaseous refrigerant is separated from the residual liquid refrigerant, thereby preventing the liquid refrigerant from entering the compressor 50 and avoiding the "liquid compression" fault (i.e., the compression of liquid refrigerant may damage the compressor 50), ensuring that the compressor 50 draws in pure gaseous refrigerant and maintains efficient operation.

[0088] The HVAC system RC also has a cooling mode. In cooling mode, the outdoor fan and indoor fan 86 operate normally, and the refrigerant circulation path is as follows: compressor 50, outdoor heat exchanger 105, outdoor expansion valve 69, indoor heat exchanger 70, gas-liquid separator 67, and compressor 50. In this configuration, the reversing valve 40 is in the first connection state. The compressor 50 compresses the low-temperature, low-pressure gaseous refrigerant into a high-temperature, high-pressure gaseous refrigerant. The high-temperature, high-pressure gaseous refrigerant enters the outdoor heat exchanger 105 through the reversing valve 40, where it exchanges heat with the outdoor air provided by the outdoor fan, which acts as a cooling source, and dissipates heat, becoming a high-pressure liquid refrigerant. After the high-pressure liquid refrigerant is depressurized by the outdoor expansion valve 69, it becomes a low-pressure liquid refrigerant. After entering the indoor heat exchanger 70, it exchanges heat with the indoor air provided by the indoor fan 86, which acts as a heating source, and evaporates, thus cooling the air passing through the indoor heat exchanger 70. The low-pressure liquid refrigerant becomes a low-temperature, low-pressure gaseous refrigerant. After the liquid refrigerant is separated by the gas-liquid separator 67, the gaseous refrigerant is reused by the compressor 50 and continues to circulate.

[0089] The HVAC system RC also has a heating mode. In heating mode, the outdoor fan and indoor fan 86 operate normally, and the refrigerant circulation path is as follows: compressor 50, indoor heat exchanger 70, outdoor expansion valve 69, outdoor heat exchanger 105, gas-liquid separator 67, and compressor 50. In this configuration, the reversing valve 40 is in the second connection state. The compressor 50 compresses the low-temperature, low-pressure gaseous refrigerant into a high-temperature, high-pressure gaseous refrigerant. The high-temperature, high-pressure gaseous refrigerant enters the indoor heat exchanger 70 through the reversing valve 40, where it exchanges heat with the indoor air provided by the indoor fan 86, which acts as a cooling source, and dissipates heat. This heats the air passing through the indoor heat exchanger 70, turning it into a high-pressure liquid refrigerant. After the high-pressure liquid refrigerant is depressurized by the indoor expansion valve 83, it becomes a low-pressure liquid refrigerant. It then enters the outdoor heat exchanger 105, where it exchanges heat with the outdoor air provided by the outdoor fan, which acts as a heating source, and evaporates, becoming a low-temperature, low-pressure gaseous refrigerant. After the liquid refrigerant is separated by the gas-liquid separator 67, the gaseous refrigerant is utilized by the compressor 50 and continues to circulate.

[0090] During the above process, the control device 500 can control the connection status of the reversing valve 40 according to the current working mode (defrosting / cooling / heating). The control device 500 can determine the current working mode and switch between working modes according to user instructions and / or preset judgment conditions.

[0091] In some exemplary embodiments, such as Figure 1 and Figure 2As shown, the outdoor unit 100 also includes an oil separator 66. The oil separator 66 is disposed between the discharge port 501 of the compressor 50 and the reversing valve 40. The first end of the oil separator 66 is connected to the discharge port 501 of the compressor 50, the second end is connected to the valve port D of the reversing valve 40, and the third end is connected to the suction port 502 of the compressor 50 via a return oil capillary tube 661. The oil separator 66 is used to separate the lubricating oil from the high-temperature, high-pressure gaseous refrigerant output by the compressor 50. The separated lubricating oil flows back to the compressor 50 through the return oil capillary tube.

[0092] The separation mechanism of the oil separator 66 can include centrifugal separation and filter separation. Centrifugal separation refers to the process where high-pressure gaseous refrigerant enters the oil separator 66 and accelerates the airflow through a rotating channel or centrifugal element. Centrifugal force is used to throw heavier lubricating oil particles towards the inner wall of the oil separator 66, where they eventually settle to the bottom. Filter separation refers to the process where part of the oil separator 661 is equipped with a filter or adsorbent material to further intercept tiny oil droplets and improve separation efficiency.

[0093] The separated lubricating oil flows slowly back to the suction port 502 of the compressor 50 through the oil return capillary tube (narrow diameter pipe) 661. The design of the oil return capillary tube 661 can control the oil return speed and avoid excessive backflow of lubricating oil, which would cause pressure fluctuations at the suction port 502 of the compressor 50.

[0094] In some exemplary embodiments, such as Figure 1 and Figure 2 As shown, the outdoor unit 100 also includes a liquid-side switching valve 51, which is disposed between the outdoor expansion valve 69 and the indoor heat exchanger 70. The liquid-side switching valve 51 is used to cut off or open the passage between the outdoor heat exchanger 105 and the indoor heat exchanger 70.

[0095] In the event of a shutdown or malfunction of the HVAC system, the liquid-side switching valve 51 effectively blocks the backflow of liquid refrigerant from the indoor side to the outdoor side by physically isolating the refrigerant circulation path between the indoor and outdoor sides, thereby preventing the compressor 50 from sucking in liquid refrigerant and causing liquid slugging, and protecting the safety of the compressor 50.

[0096] In some exemplary embodiments, the outdoor unit 100 further includes a gas-side switching valve 52 disposed between the indoor heat exchanger 70 and the valve port E of the reversing valve 40. The gas-side switching valve 52 is used to cut off or open the passage between the indoor heat exchanger 70 and the valve port E of the reversing valve 40.

[0097] During system maintenance, shutdown, or mode switching, closing the gas-side switch valve 52 physically isolates the refrigerant path between the indoor heat exchanger 70 and the reversing valve 40, blocking the flow of gaseous refrigerant. This prevents sudden pressure changes caused by switching the reversing valve 40 or starting and stopping the compressor 50, protecting critical components such as the compressor 50 and heat exchanger from mechanical shock. During the switching of the reversing valve 40 (e.g., from cooling to heating), this valve effectively prevents gaseous refrigerant from flowing back to the compressor 50 or condenser, reducing the risk of liquid slugging or cavitation. Simultaneously, when repairing the indoor heat exchanger 70 or the reversing valve 40, closing the gas-side switch valve 52 prevents refrigerant loss and simplifies the operation process (no need to purge the entire system).

[0098] In some exemplary embodiments, such as Figure 1 and Figure 2 As shown, the HVAC system also includes a control device 500, which is located between the outdoor expansion valve 69 and the indoor heat exchanger 70. Figure 25 As shown, the control device 500 includes an acquisition module 501, a judgment module 502, and a drive module 503. The acquisition module 501 is configured to acquire various environmental information (e.g., indoor temperature, outdoor temperature, etc.), operating status information of various components (e.g., power, voltage, running time, etc.), and other information. The acquisition module 501 then outputs the acquired data to the judgment module 502. The judgment module 502 is configured to compare, time, and switch states based on the data acquired from the acquisition module 501 and preset control logic (e.g., defrosting mode entry / exit conditions, etc.), and output control commands. Subsequently, the judgment module 502 outputs the control commands to the drive module 503. The drive module 503 is configured to drive various components (e.g., relays, frequency converters, fans, reversing valves, compressors, etc.) to perform operations according to the control commands received from the judgment module 502.

[0099] The control device 500 may also be equipped with a heat dissipation component to dissipate heat from the acquisition module 501, the judgment module 502 and the drive module 503.

[0100] like Figures 2-9 As shown, the outdoor unit 100 provided in this embodiment includes a collector 1, a heat exchange body 2, and a distributor 3.

[0101] This application embodiment provides a collector 1 including a main tube 10 and branch tubes 11. The collector 1 includes a main tube 10 and a plurality of branch tubes 11. The main tube 10 extends along the height direction, and a plurality of connection holes are spaced apart along the height direction on the tube wall of the main tube 10. The height of the plurality of connection holes is defined by a minimum height. Connection holes located at the minimum height are defined as first type connection holes 101, and connection holes higher than the minimum height are defined as second type connection holes 102. The plurality of branch tubes 11 are connected to the plurality of connection holes one by one. Each branch tube 11 includes a first shaft end 111 connected to the connection hole and a second shaft end 112 configured to connect to a heat exchange flow path 20. Branch tubes 11 connected to the first type connection holes 101 are defined as first type branch tubes 12, and branch tubes 11 connected to the second type connection holes 102 are defined as second type branch tubes 13. The height of the first type connection holes 101 is configured to be lower than the height of at least a portion of the heat exchange flow path 20 connected to the first type branch tubes 12.

[0102] The heat exchanger body 2 provided in this embodiment includes multiple heat exchange flow paths 20. The supported plane 14 of the heat exchanger body 2 is defined as the height reference plane HP, and the direction perpendicular to the height reference plane HP is defined as the height direction. The multiple heat exchange flow paths 20 are arranged sequentially in the height direction. Each heat exchange flow path 20 has a first connector J1 and a second connector J2 formed at both ends. Each branch pipe 11 of the collector 1 is connected to at least one corresponding heat exchange flow path 20, and the heat exchange flow path 20 connected to the first type of branch pipe 12 of the collector 1 is defined as the first type of heat exchange flow path 20. The height of the first type of connection hole 101 of the collector 1 is lower than at least a portion of the height of the first type of heat exchange flow path 20.

[0103] The distributor 3 provided in this embodiment includes a flow distribution body 30 and a plurality of flow distribution pipes 31 connected to the flow distribution body 30. The plurality of flow distribution pipes 31 can be connected one-to-one with a plurality of heat exchange flow paths 20 of the heat exchange body 2. Alternatively, two or more of the plurality of heat exchange flow paths 20 can be connected to one of the plurality of flow distribution pipes 31.

[0104] The lowest heat exchange path among the multiple heat exchange paths 20 is defined as the defrosting path 21. The second connector J2 of the defrosting path 21 is connected to a shunt pipe 31 that is thermally connected to a defrosting temperature sensor T3. The multiple heat exchange paths 20 may also include a temperature sensing path 22, which is located above the defrosting path 21. The temperature sensing path 22 is equipped with an intermediate temperature sensor T3B, which is positioned between the first connector J1 and the second connector J2 of the temperature sensing path 22.

[0105] The heat exchanger body 2 provided in this embodiment includes multiple heat exchange fins 24, multiple U-shaped tubes 25, and multiple elbows 26. Each U-shaped tube 25 is integrally formed by bending the same tube material, which is made of copper or aluminum. It includes two parallel straight tube sections 251 and an integrally connected bent tube section 252. The end of each straight tube section 251 away from the bent tube section 252 is configured as an open end 2511. The elbows 26 are hollow tubular multi-way connectors used to sequentially connect the open ends 2511 of multiple U-shaped tubes 25. The elbows 26 are made of the same material as the U-shaped tubes 25. The elbows 26 can be two-way or three-way connectors. A two-way elbow 26 connects two U-shaped tubes 25, and a three-way elbow 26 connects three U-shaped tubes 25. The open end 2511 of the straight pipe section 251 is flared, and the inner diameter of the open end 2511 is larger than the inner diameter of the main pipe section of the straight pipe section 251. The hollow interior of the open end 2511 is used for the insertion of the elbow 26, the branch pipe 11 and the diversion pipe 31. The inner diameter of the corresponding insertion part is equal to the inner diameter of the main pipe section of the straight pipe section 251, thereby reducing the loss of refrigerant pressure drop.

[0106] The heat exchange fins 24 are plate-shaped and extend longitudinally in the height direction. The material of the heat exchange fins 24 is aluminum. Each fin 24 has multiple perforations arranged in multiple rows. The perforations penetrate the heat exchange fins 24 along the thickness direction. The multiple rows of perforations are arranged alternately along the width direction. Each row of perforations is arranged alternately along the height direction, and the number of perforations in each row is the same. Two perforations with the same serial number in two adjacent rows are staggered in the height direction. Two adjacent perforations in each row are defined as a pair of perforations. A pair of perforations corresponds to the insertion of one U-shaped tube 25. Multiple pairs of perforations in each row correspond to the insertion of multiple U-shaped tubes 25.

[0107] Each U-shaped tube 25 has multiple heat exchange fins 24 inserted into its straight tube section 251. These fins are arranged in a row along the axial direction of the straight tube section 251 of the U-shaped tube 25. The lower edges of the row of heat exchange fins lie on the same plane, which is the supported plane 14 of the outdoor heat exchanger. The supported plane 14 is supported by the support surface 41 of the chassis 4 of the casing (see [reference]). Figure 5 and Figure 6 On the surface using the same filling pattern as the support surface 41), an air inlet gap G is formed between any two adjacent heat exchange fins 24 (e.g., ...). Figure 4As shown), the heat exchange air source flows through the air inlet gap G and passes through the heat exchange body 2. A row of heat exchange fins 24 is defined as the first side 241 and the second side 242 along the arrangement direction. The bent portion 252 of each U-shaped tube 25 is exposed on the first side 241, and the two open ends 2511 of the two straight tube portions 251 of each U-shaped tube 25 are exposed on the second side 242. Multiple U-shaped tubes 25 are interspersed with corresponding pairs of perforations, and multiple U-shaped tubes 25 form multiple rows along the width direction of the plate. The straight tube portions 251 of each row of U-shaped tubes 25 are arranged sequentially at intervals along the height direction. The two straight tube portions 251 of the same number in two adjacent rows of U-shaped tubes 25 are staggered in height direction, thereby improving the heat exchange efficiency between the heat exchange air source and the straight tube portions 251.

[0108] Multiple U-shaped tubes 25 are arranged in multiple rows along the air inlet direction of the heat exchange body 2, with the air inlet direction perpendicular to the height direction. Each row of U-shaped tubes 25 includes multiple U-shaped tubes 25 spaced apart along the height direction, and adjacent rows of U-shaped tubes 25 are staggered along their rowing direction.

[0109] Each heat exchange path 20 is formed by sequentially connecting multiple U-shaped tubes 25. Two adjacent U-shaped tubes 25 along the refrigerant flow direction are connected by a bend joint 26. One open end 2511 of the first U-shaped tube 25 forms the first joint J1 of the heat exchange path 20, and one open end 2511 of the last U-shaped tube 25 forms the second joint J2 of the heat exchange path 20. The row of U-shaped tubes 25 closest to the windward side 2a is defined as the windward row, and the row of U-shaped tubes 25 closest to the leeward side 2b is defined as the leeward row. One of the first joint J1 and the second joint J2 of each heat exchange path 20 is located in one of the windward and leeward rows, and the other of the first joint J1 and the second joint J2 of each heat exchange path 20 is located in the other row.

[0110] exist Figure 2 In the schematic diagram, for ease of understanding, the first connector J1 and the second connector J2 of the heat exchange flow path 20 are shown as located on both sides of the heat exchange body 2 along the extension direction of the straight pipe section 251. In practice, as... Figure 5A and Figure 5B As shown in the structural diagram, the first connector J1 and the second connector J2 of the heat exchange flow path 20 are located in different columns on the same side of the heat exchange body 2.

[0111] The outdoor unit 100 provided in this embodiment includes an outdoor unit housing 104, which includes a chassis 4, a top cover (not shown), and a side wall portion (not shown) located between the chassis 4 and the top cover. Figure 6As shown, the chassis 4 includes a support portion arranged along the edge of the chassis 4. The upper surface of the support portion forms a support surface 41, which supports the bottom surface of the heat exchange body 2 of the outdoor heat exchanger, forming a supported plane 14. Multiple drainage grooves 42 are recessed downwards from the support surface 41. The bottom wall of the drainage grooves 42 is lower than the support surface 41 and has a certain gap with the supported plane 14. The chassis 4 is provided with multiple drainage holes 43 and drainage channels 45. Some drainage holes penetrate downwards from the support surface 41, some drainage holes 43 penetrate downwards from the bottom wall of the drainage grooves 42, and some drainage holes 43 penetrate downwards from the chassis 4. The chassis 4 also includes a flange 44 arranged around its perimeter. Water melted during defrosting, condensate generated during operation, or rainwater that seeps in is discharged outside the casing through the drainage channels 45 and drainage holes 43. Figure 7 As shown, the drainage channel 42 is designed as a slope, which facilitates the smooth discharge of condensate and rainwater from the casing by gravity, and provides a certain amount of space for accumulated water so that in the event of drainage difficulties, the accumulated water will not soak the heat exchanger body 2. Furthermore, there is a certain gap between the flange 44 and the heat exchanger body 2, ensuring that the heat exchanger body 2 will not collide or rub against the flange 44 during installation and operation, thus avoiding damage to either the heat exchanger body 2 or the chassis 4. This also provides space for accumulated water and rainwater to flow and drain.

[0112] The bottom of the manifold 1 is not supported on the support surface 41 of the chassis 4, but there is a gap between the manifold 1 and the chassis 4 to prevent vibrations from the chassis 4 from being transmitted to the manifold 1. Because the bottom of the manifold 1 is a certain distance above the support surface 41 of the chassis 4, and for tooling requirements, the lowest first-type connection hole 101 of the manifold 1 is a certain distance from the bottom of the manifold 1, after assembly, the first-type connection hole 101 of the manifold 1 is higher than at least part of the defrosting flow path 21, for example, it may not be lower than the height of the lowest first connector J1 of the heat exchange body 2. If the first-type connection hole 101 of the manifold 1 is directly connected to the lowest first connector J1 of the heat exchange body 2, the accumulated liquid LQ at the bottom of the manifold 1 can easily flow to the lowest first connector J1 under gravity, and then enter the defrosting flow path 21, affecting the energy efficiency of the HVAC system. Therefore, in this embodiment of the application, the first connector J1 at the bottom of the heat exchange body 2 is connected to the second type of connection hole 102 of the collector 1 to prevent the accumulated liquid LQ from flowing into the heat exchange body 2 under the action of gravity.

[0113] In this embodiment, the height of the first connector J1 at the bottom of the defrosting flow path 21 (the height from the height reference plane) is defined as H0, the height of the first type of connection hole 101 is defined as H1, the height of the next lower connection hole (the second type of connection hole 102 at the bottom) is defined as H2, and the height of the first connector J1 of the next lower heat exchange flow path 23 is defined as H3.

[0114] In an exemplary embodiment, as Figure 10 and Figure 11 shown, the main pipe 10 of the collector 1 includes a first type of connection hole 101 at the minimum height, and the heat exchange main body 2 includes a defrosting flow path 21 (the part delimited by the dashed line) at the bottommost position. In Figure 10 and Figure 11 the shown embodiment, H1 = H0 < H3 < H2. The first type of branch pipe 12 connected to the first type of connection hole 101 extends from low to high and is connected to the first joint J1 below the second lowest position of the defrosting flow path 21. The second type of branch pipe 13 connected to the lowermost second type of connection hole 102 extends from low to high and is connected to the first joint J1 of the heat exchange flow path below the second lowest position above the defrosting flow path 21. The second type of branch pipe 13 connected to the second type of connection hole 102 below extends from high to low and is connected to the first joint J1 at the bottommost position of the defrosting flow path 21. The second shaft end 112 of the first type of branch pipe 12 is higher than the second shaft end 112 of the second type of branch pipe 13 connected to the second type of connection hole 102 below, and the second shaft end 112 of the second type of branch pipe 13 connected to the lowermost second type of connection hole 102 is higher than the second shaft end 112 of the second type of branch pipe 13 connected to the second type of connection hole 102 below. The extension trajectories of the second type of branch pipe 13 connected to the second type of connection hole 102 below respectively cross the extension trajectories of the first type of branch pipe 12 and the second type of branch pipe 13 connected to the lowermost second type of connection hole 102. The defrosting flow path 21 includes two first joints J1 and one second joint J2. Through the above arrangement, the accumulated liquid LQ at the lower end of the main pipe 10 will not flow from the first type of connection hole 101 to the defrosting flow path 21 due to the action of gravity or the driving of the refrigerant flow, avoiding the accumulated liquid LQ from affecting the temperature rise of the defrosting flow path 21, reducing the ineffective defrosting time of other heat exchange flow paths 20, and improving the energy efficiency of the HVAC system. In addition, there is usually more refrigerant in the defrosting flow path 21 due to the action of gravity and thus the temperature is lower. In the above arrangement, the refrigerant flowing out from the first type of connection hole 101 and the lowermost second type of connection hole 102 flows into the defrosting flow path 21 from the two second joints J2 and then flows out from one second joint J2, making the temperature of the defrosting flow path 21 rise faster and further reducing the ineffective defrosting time of other heat exchange flow paths 20.

[0115] Exemplarily, as Figure 8 shown, the collector 1 can be a flute-shaped pipe, and the connection hole can be a flanged hole.

[0116] Exemplarily, the material of the main pipe 10 of the collector 1 can be metal, such as stainless steel. One axial end of the main pipe 10 is sealed by a cover to form a closed end, and a connecting pipe is provided at the other end. The materials of the plurality of branch pipes 11 and the heat exchange flow path 20 can be metal, such as copper or aluminum. The branch pipes 11 made of the same material can be connected to the heat exchange flow path 20 made of the same material. For example, the branch pipes 11 made of copper material are connected to the heat exchange flow path 20 made of copper material.

[0117] In an exemplary embodiment, as Figure 12 shown, the first type of branch pipe 12 extends from low to high and connects to the first joint J1 of the heat exchange flow path at the level above the heat exchange flow path 23 below. The second type of branch pipe 13 connected to the second type of connection hole 102 at the bottom extends from high to low and connects to the first joint J1 of the defrosting flow path 21. The second type of branch pipe 13 connected to the second type of connection hole 102 below extends from high to low and connects to the first joint J1 of the heat exchange flow path 23 below. The second shaft end 112 of the first type of branch pipe 12 is higher than the second shaft end 112 of the second type of branch pipe 13 connected to the second type of connection hole 102 at the bottom, and is higher than the second shaft end 112 of the second type of branch pipe 13 connected to the second type of connection hole 102 below. The extension trajectory of the first type of branch pipe 12 intersects with the extension trajectories of the second type of branch pipe 13 connected to the second type of connection hole 102 at the bottom and the second type of branch pipe 13 connected to the second type of connection hole 102 below. The defrosting flow path 21 further includes a second joint J2 for connecting to the shunt pipe 31 of the distributor 3. In Figure 12 the shown embodiment, H0 = H1 < H3 < H2. In the above arrangement, the first joint J1 of the heat exchange flow path at the level above the heat exchange flow path 23 below connected by the second shaft end 112 of the first type of branch pipe 12 is higher than Figure 9 the first joint J1 below of the defrosting flow path 21 in the embodiment, further preventing the accumulated oil in the main pipe 10 of the collector 1 from flowing into the heat exchange flow path, and further ensuring that the temperature rise of the heat exchange flow path is not affected by the accumulated oil.

[0118] In an exemplary embodiment, as Figure 13As shown, the first type of branch pipe 12 extends from low to high and connects to the first joint J1 of the heat exchange flow path above the next lower heat exchange flow path 23. The second type of branch pipe 13, connected to the next lower second type of connection hole 102, extends from high to low and connects to the first joint J1 of the next lower heat exchange flow path 23. The second type of branch pipe 13, connected to the lowest second type of connection hole 102, extends from high to low and connects to the first joint J1 of the defrosting flow path 21. The second shaft end 112 of the first type of branch pipe 12 is higher than the second shaft end 112 of the second type of branch pipe 13 connected to the lowest second type of connection hole 102, and also higher than the second shaft end 112 of the second type of branch pipe 13 connected to the next lower second type of connection hole 102. At the same time, the second shaft end 112 of the second type of branch pipe 13 connected to the next lower second type of connection hole 102 is higher than the second shaft end 112 of the second type of branch pipe 13 connected to the lowest second type of connection hole 102. The extension trajectory of the first type of branch pipe 12 intersects with the extension trajectory of the second type of branch pipe 13 connected to the lowest second type of connection hole 102 and the extension trajectory of the second type of branch pipe 13 connected to the next lower second type of connection hole 102. The second connector J2 of the defrosting flow path 21 and the second connector J2 of the next lower heat exchange flow path 23 are connected to the same branch pipe 31. Figure 13 In the embodiment shown, H0

[0119] In one exemplary embodiment, such as Figure 14 ​As shown, the first type of branch pipe 12 extends from low to high and connects to the first joint J1 of the heat exchange flow path 23 below the next level, and the second type of branch pipe 13 connected to the second type of connection hole 102 below the next level extends from high to low and connects to the first joint J1 below the next level of the defrosting flow path 21. The second type of branch pipe 13 connected to the second type of connection hole 102 at the bottom extends from high to low and connects to the first joint J1 at the bottom of the defrosting flow path 21. The second shaft end 112 of the first type of branch pipe 12 is higher than the second shaft end 112 of the second type of branch pipe 13 connected to the second type of connection hole 102 at the bottom and higher than the second shaft end 112 of the second type of branch pipe 13 connected to the second type of connection hole 102 below the next level. At the same time, the second shaft end 112 of the second type of branch pipe 13 connected to the second type of connection hole 102 below the next level is higher than the second shaft end 112 of the second type of branch pipe 13 connected to the second type of connection hole 102 at the bottom. The extension trajectory of the first type of branch pipe 12 intersects with the extension trajectories of the second type of branch pipe 13 connected to the second type of connection hole 102 at the bottom and the second type of branch pipe 13 connected to the second type of connection hole 102 below the next level. The defrosting flow path 21 includes two first joints J1 and one second joint J2. In Figure 14 In the illustrated embodiment, H0 = H1 < H3 < H2. Through the above arrangement, not only are there two refrigerant flows into the defrosting flow path 21, but the second shaft end 112 of the first type of branch pipe 12 is also set higher than the second shaft end 112 of the second type of branch pipe 13 connected to the second type of connection hole 102 below the next level and the second shaft end 112 of the second type of branch pipe 13 connected to the second type of connection hole 102 at the bottom. Thus, while increasing the heating rate of the defrosting flow path 21, it further prevents accumulated oil from flowing into the heat exchange main body 2, improving the energy efficiency of the HVAC system.

[0120] In an exemplary embodiment, as Figure 15 and Figure 16 shown, the second shaft end 112 of the first type of branch pipe 12 is set to be multi-forked to form a plurality of branch joints 15; the second shaft end 112 of the second type of branch pipe 13 is also set to be multi-forked to form a plurality of branch joints 15. It should be understood that in other embodiments, only the second shaft end 112 of either the first type of branch pipe 12 or the second type of branch pipe 13 can be set to be multi-forked, and the other of the two can be set to Figures 11-14The single-tube shape is shown. A second-type branch pipe 13, connected to the lowest second-type connection hole 102, extends from high to low and connects to the lowest first connector J1 and the next lowest first connector J1 of the defrosting flow path 21. A first-type branch pipe 12 extends from low to high and connects to the first connector J1 of the next lowest heat exchange flow path 23 and the first connector J1 of the heat exchange flow path above the next lowest heat exchange flow path 23. The second shaft end 112 of the first-type branch pipe 12 is higher than the second shaft end 112 of the second-type branch pipe 13 connected to the lowest second-type connection hole 102. The extension trajectory of the first-type branch pipe 12 intersects with the extension trajectory of the second-type branch pipe 13 connected to the lowest second-type connection hole 102. The defrosting flow path 21 includes two first connectors J1 and one second connector J2. Figure 15 and Figure 16 In the embodiment shown, H0 <H3

[0121] In one exemplary embodiment, such as Figure 17 As shown, an arrangement of the branch pipes 31 of the distributor 3 is illustrated. The distributor 3 includes a plurality of branch pipes 31. A defrosting temperature sensor T3 is provided on the lowermost branch pipe 31 among the plurality of branch pipes 31. The plurality of branch pipes 31 are connected one-to-one with the second connector J2 of the heat exchange flow path.

[0122] In one exemplary embodiment, such as Figure 18 As shown, another arrangement of the branch pipes 31 of the distributor 3 is illustrated, wherein the distributor 3 includes a plurality of branch pipes 31, and a defrost temperature sensor T3 is disposed on the lowermost branch pipe 31. The lowermost branch pipe 31 is connected to two second connectors J2 through a connecting connector (T-connector), and the other branch pipes 31 are connected to the other second connectors J2 in a one-to-one correspondence. It should be understood that in other embodiments, more than one branch pipe 31 may be connected to two or more second connectors J2 through connecting connectors, and the other branch pipes 31 are connected to the other second connectors J2 in a one-to-one correspondence.

[0123] In one exemplary embodiment, such as Figure 19 ​As shown, the distributor 3 also includes a diversion body 30 and a collection pipe 32. The diversion body 30 has a diversion cavity 304 and a plurality of diversion holes 302 connected to the diversion cavity 304. The collection pipe 32 is welded and fixed to the diversion body 30 (forming a weld layer W between the two) and is connected to the diversion cavity 304. One end of the diversion hole 302 is connected to the diversion cavity 304, and the other end of the diversion hole 302 penetrates the outer surface of the diversion body 30. Each diversion hole 302 includes a plug-in part 301 and a diversion channel 303. The plug-in part 301 is formed at the other end of the diversion hole 302 and penetrates the outer surface of the diversion body 30. The diversion channel 303 connects the plug-in part 301 and the diversion cavity 304. Multiple diversion holes 302 form multiple insertion portions 301 and multiple diversion channels 303. Multiple diversion pipes 31 are inserted into the multiple insertion portions 301 in a one-to-one correspondence. The multiple diversion pipes 31 are respectively connected to the multiple diversion channels 303 in a one-to-one correspondence. The diversion channels 303 connect the diversion pipes 31 and the diversion cavity 304. One end of the diversion body 30 is for insertion of multiple diversion pipes 31, and the other end is for insertion of the summing pipe 32. The other end of the diversion body 30 also includes a throttling orifice 305 for throttling. The throttling orifice 305 is located between the diversion cavity 304 and the summing pipe 32, and the diameter of the throttling orifice 305 is smaller than the minimum size of the diversion cavity 304 and the minimum inner diameter of the summing pipe 32, thereby forming a Venturi structure.

[0124] In one exemplary embodiment, such as Figure 20 The diagram schematically illustrates the connections of both the defrosting flow path 21 and the temperature sensing flow path 22 to the main body tube 10 of the collector 1 and the branch tube 31 of the distributor 3. The temperature sensing flow path 22 can be any of the heat exchange flow paths above the defrosting flow path 21. For example, the temperature sensing flow path 22 can be the uppermost heat exchange flow path of the heat exchange body 2. A defrosting temperature sensor T3 is disposed in the branch tube 31 connected to the second connector J2 of the defrosting flow path 21 and is thermally connected to the branch tube 31. An intermediate temperature sensor T3B is disposed between the first connector J1 and the second connector J2 of the temperature sensing flow path 22. Figure 20 In the heat exchange body 2, the intermediate sensor is thermally connected to the bend 26 of the temperature sensing flow path 22. Alternatively, the intermediate temperature sensor T3B can be thermally connected to the bend 252 of the temperature sensing flow path 22. The collector 1 and the distributor 3 are located on the same side of the heat exchange body 2.

[0125] This disclosure also provides a defrosting method applied to the aforementioned HVAC system.

[0126] like Figure 23 As shown, the defrosting method includes: Step 700: When the HVAC system is running in heating mode, determine whether to enter defrost mode based on the temperature value detected by defrost temperature sensor T3 and the temperature value detected by intermediate temperature sensor T3B. Step 710: When the HVAC system is running in defrost mode, determine whether to exit defrost mode based on the temperature value detected by defrost temperature sensor T3 and the temperature value detected by intermediate temperature sensor T3B.

[0127] In some exemplary embodiments, step 700 includes: If the minimum value between the temperature detected by the defrost temperature sensor T3 and the temperature detected by the intermediate temperature sensor T3B is lower than a first preset value, the system will enter defrost mode. The first preset value can be ≤0℃.

[0128] In some exemplary embodiments, step 710 includes: like Figure 21 As shown, if the minimum value between the temperature detected by the defrost temperature sensor T3 and the temperature detected by the intermediate temperature sensor T3B is greater than a second preset value, the defrost mode is exited; or, if the rate of change of the temperature detected by the defrost temperature sensor T3 is greater than a preset rate, the defrost mode is exited. The second preset value can be greater than 0°C.

[0129] Using the rate of change of the temperature value sensed by the defrost temperature sensor T3 (i.e., the temperature change trend) as the condition for exiting defrost mode (i.e., judging based on the temperature change trend), and using the temperature value detected by the defrost temperature sensor T3 as the condition for exiting defrost mode, the exit time points for these two methods can be determined as follows: Figure 21 As shown, using the rate of change of the temperature value sensed by the defrost temperature sensor T3 to determine the exit time of defrost mode is significantly earlier than using the temperature value sensed by the defrost temperature sensor T3 to determine the exit time of defrost mode, thus allowing the defrost mode to exit earlier.

[0130] Of course, the decision to enter or exit defrost mode can also be determined solely based on the temperature value detected by the defrost temperature sensor T3. For example, in some other exemplary embodiments, such as Figure 22 As shown, a defrosting method, applied to the aforementioned HVAC system, includes: Step 600: When the HVAC system is running, determine whether to enter defrost mode based on the temperature value detected by the defrost temperature sensor T3; Step 610: When the HVAC system is running in defrost mode, determine whether to exit defrost mode based on the temperature value detected by the defrost temperature sensor T3.

[0131] In heating mode, if the temperature value detected by defrost temperature sensor T3 is lower than a first preset value, defrost mode is entered. In defrost mode, if the temperature value detected by defrost temperature sensor T3 is higher than a second preset value, defrost mode is exited; or, if the rate of change of the temperature value detected by defrost temperature sensor T3 is greater than a preset rate, defrost mode is exited. The first preset value can be ≤0℃, and the second preset value can be >0℃.

[0132] This disclosure also provides a defrosting method, such as... Figure 24 As shown, it includes: Step 800: Heating system operation.

[0133] When the HVAC system is in normal heating mode, the reversing valve 40 is in the state where valve interface E is connected to valve interface D and valve interface S is connected to valve interface C.

[0134] Step 801: Detect whether the minimum value of temperature T3 and T3B is lower than the judgment value A. If it is not lower than the judgment value A, proceed to step 800. If it is lower than the judgment value A, proceed to step 802.

[0135] Step 802: Enter the reverse defrosting operation state.

[0136] Step 803: The compressor frequency is reduced to the first preset frequency Ft_def1 and maintained for a time t1.

[0137] Step 804: Reverse the direction of the reversing valve 40 so that valve interface E is connected to valve interface S and valve interface D is connected to valve interface C, and increase the frequency of the compressor to the second preset frequency Ft_def2.

[0138] At this time, the outdoor heat exchanger acts as a condenser and uses the heat from the refrigerant for defrosting.

[0139] Step 805: During the defrosting process, check whether the maximum value of T3 and T3B is greater than the judgment value B. If it is greater than the judgment value B, proceed to step 806; otherwise, proceed to step 805.

[0140] Step 806: The compressor frequency is first reduced to the third preset frequency Ft_def3 and maintained for time t2.

[0141] Step 807: The reversing valve 40 is reversed, so that the reversing valve 40 is connected to valve interface E-valve interface D and valve interface S-valve interface C, and the compressor frequency is raised to the fourth preset frequency Ft_def4 for normal heating operation.

[0142] Where t1 and t2 < 5 min, 0 ≤ Ft_def1 ≤ Ft_def2, 0 ≤ Ft_def3 ≤ Ft_def2, A ≤ 0℃, and B > 0℃.

[0143] This disclosure also provides a control device 500 for a heating, ventilation, and air conditioning (HVAC) system. The control device 500 includes a memory and a processor. The memory is configured to store an executable program. The processor is configured to read and execute the executable program to implement the control method for the HVAC system as described in any embodiment of this disclosure.

[0144] This disclosure also provides a computer-readable storage medium storing a computer program, wherein when the computer program is executed by a processor, it can implement the control method of the HVAC system as described in any of the above embodiments.

[0145] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this application and 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, and therefore should not be construed as a limitation of this application.

[0146] Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first," "second," etc., may explicitly or implicitly include at least one of those features.

[0147] In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise expressly and specifically limited.

[0148] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," "fixing," etc., should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral part; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be a connection within two components or an interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0149] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0150] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," 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 this application. 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. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0151] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. An outdoor heat exchanger, comprising a collector, a distributor, and a heat exchange body located between the collector and the distributor, the heat exchange body comprising a plurality of heat exchange flow paths, the supported plane of the heat exchange body being defined as a height reference plane, and the direction perpendicular to the height reference plane being defined as the height direction; The collector includes a main tube extending along the height direction and multiple branch tubes. The wall of the main tube is provided with multiple connection holes spaced apart along the height direction. The multiple connection holes are connected to the multiple branch tubes one by one. The multiple connection holes are defined with a minimum height relative to the height reference plane. The connection holes located at the minimum height are defined as first type connection holes, and the connection holes above the minimum height are defined as second type connection holes. The distributor includes a distribution body and multiple branch pipes connected to the distribution body; Multiple heat exchange flow paths are arranged sequentially in the height direction. Each heat exchange flow path has a first connector and a second connector at both ends. Each first connector is connected to the corresponding branch pipe, and each second connector is connected to the corresponding diversion pipe. The lowest heat exchange flow path among the multiple heat exchange flow paths is defined as the defrosting flow path. The first connector at the bottom is the first connector of the defrosting flow path and is connected to the second type of connection hole via the corresponding branch pipe. A defrosting temperature sensor is thermally connected to the shunt pipe connected to the second connector of the defrosting flow path.

2. The outdoor heat exchanger according to claim 1, characterized in that, The defrosting flow path has one first connector and one second connector. The first connector of the defrosting flow path is the bottommost first connector, and the second connector of the defrosting flow path is the bottommost second connector.

3. The outdoor heat exchanger according to claim 1, characterized in that, The defrosting flow path has multiple first connectors, including the lowest first connector and the next lowest first connector, and the next lowest first connector is connected to either the first type of connection hole or the second type of connection hole.

4. The outdoor heat exchanger according to claim 3, characterized in that, The number of second connectors in the defrosting flow path is one, and the second connector in the defrosting flow path is the lowest second connector; or, The number of second connectors in the defrosting flow path is multiple, including the lowest second connector.

5. The outdoor heat exchanger according to claim 1, characterized in that, The number of the shunt pipes and the number of the second connectors are equal and connected in a one-to-one correspondence; or, the number of the shunt pipes is less than the number of the second connectors, and at least one of the shunt pipes is connected to multiple second connectors simultaneously.

6. The outdoor heat exchanger according to claim 1, characterized in that, The defrosting flow path includes multiple branch paths and a main flow path formed by the convergence of the multiple branch paths. Each of the multiple branch paths corresponds to a multiple first connector, and each of the main flow paths corresponds to a second connector. The multiple first connectors of the multiple branch paths include the lowest first connector and the next lowest first connector.

7. The outdoor heat exchanger according to claim 6, characterized in that, Each of the first connectors of the branch path is connected to a corresponding connection hole via a corresponding branch pipe. The branch pipe corresponding to the lowest first connector is defined as the lowest branch pipe, and the branch pipe corresponding to the next lowest first connector is defined as the next lowest branch pipe. The first connector at the bottom is connected to the second type of connection hole via the bottommost branch pipe, and the first connector at the next bottom is connected to the first type of connection hole via the next bottommost branch pipe. The extension trajectory of the bottommost branch pipe and the extension trajectory of the next bottommost branch pipe intersect in the height direction.

8. The outdoor heat exchanger according to claim 6, characterized in that, Each of the first connectors of the branch path is connected to a corresponding connection hole via a corresponding branch pipe. The branch pipe corresponding to the lowest first connector is defined as the lowest branch pipe, and the branch pipe corresponding to the next lowest first connector is defined as the next lowest branch pipe. The first connector at the bottom is connected to a second type of connection hole via the bottommost branch pipe, and the first connector at the next bottom is connected to another second type of connection hole via the next bottommost branch pipe. The extension trajectory of the bottommost branch pipe is lower than that of the next bottommost branch pipe. The heat exchange flow path of the first stage of the defrosting flow path is defined as the secondary lower heat exchange flow path. The first joint of the secondary lower heat exchange flow path is connected to the first type of connection hole through the corresponding branch pipe. The extension trajectory of the branch pipe corresponding to the first joint of the secondary lower heat exchange flow path intersects with the extension trajectory of the lowest branch pipe and the extension trajectory of the secondary lower branch pipe in the height direction.

9. The outdoor heat exchanger according to claim 6, characterized in that, The multiple first connectors of the multiple branch paths are connected to a second type of connection hole via a corresponding branch pipe. The first shaft end of the corresponding branch pipe is constructed as a single tube and inserted into the second type of connection hole. The second shaft end of the corresponding branch pipe is constructed as a multi-branch pipe and is connected to the multiple first connectors of the multiple branch paths one by one. The corresponding branch pipe extends from the first shaft end from high to low to the second shaft end.

10. The outdoor heat exchanger according to claim 1, characterized in that, Each heat exchange flow path includes multiple branch flow paths and a main flow path formed by the convergence of the multiple branch flow paths. Each of the multiple branch flow paths corresponds to a multiple first connector, and each of the main flow paths corresponds to a second connector. In this configuration, the first connector of each branch path is connected to a corresponding connection hole via a corresponding branch pipe; or, the multiple first connectors of multiple branches of each heat exchange flow path are connected to a corresponding connection hole via a corresponding branch pipe.

11. The outdoor heat exchanger according to claim 1, characterized in that, The first connector below the next level is connected to the first type of connection hole via the corresponding branch pipe. The height of the first connector below the next level is greater than the height of the first type of connection hole. The branch pipe corresponding to the first connector below the next level extends from the first connector below the next level to the first type of connection hole from high to low.

12. The outdoor heat exchanger according to any one of claims 1-11, characterized in that, The outdoor heat exchanger has a defrosting mode, and the defrosting mode is triggered when the value detected by the defrosting temperature sensor is lower than a first preset value. The conditions for exiting the defrost mode include at least: the defrost temperature sensor value is higher than the second preset value; Wherein, the first preset value is less than the second preset value.

13. The outdoor heat exchanger according to claim 12, characterized in that, Each heat exchange flow path includes a plurality of U-shaped tubes and at least one elbow joint that connects the plurality of U-shaped tubes in sequence. Each U-shaped tube includes two straight tube sections and an elbow section integrally connected to the two straight tube sections. The straight tube section includes an open end away from the elbow section and a main pipe section located between the open end and the elbow section. The outer diameter of the main pipe section is any one of 5 mm, 7 mm, and 9.52 mm.

14. The outdoor heat exchanger according to any one of claims 1-11, characterized in that, The heat exchange flow path further includes a temperature sensing flow path, which is disposed above the defrosting flow path. An intermediate temperature sensor is provided on the temperature sensing flow path, and the intermediate temperature sensor is disposed between the first connector and the second connector of the temperature sensing flow path.

15. The outdoor heat exchanger according to claim 14, characterized in that, The outdoor heat exchanger has a defrosting mode, and the defrosting mode is triggered when the minimum value of the defrosting temperature sensor and the intermediate temperature sensor is lower than a first preset value. The conditions for exiting the defrost mode include: the maximum value of the detection value of the defrost temperature sensor and the detection value of the intermediate temperature sensor is higher than a second preset value; Wherein, the first preset value is less than the second preset value.

16. The outdoor heat exchanger according to claim 14, characterized in that, Each heat exchange flow path includes a plurality of U-shaped tubes and at least one elbow joint that connects the plurality of U-shaped tubes in sequence. Each U-shaped tube includes two straight tube sections and an elbow section integrally connected to the two straight tube sections. The intermediate temperature sensor is thermally connected to the elbow section of the temperature sensing flow path, or the intermediate temperature sensor is thermally connected to the elbow joint of the temperature sensing flow path.

17. The outdoor heat exchanger according to claim 16, characterized in that, The straight pipe section includes an open end away from the bend section and a main pipe section located between the open end and the bend section, wherein the outer diameter of the main pipe section is 5 mm.

18. An outdoor unit, characterized in that, Includes the outdoor heat exchanger as described in any one of claims 1-17.

19. A heating, ventilation, and air conditioning system, characterized in that, It includes the outdoor unit unit as described in claim 18 and the indoor unit unit connected to the outdoor unit unit.

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