Multi-outdoor-unit direct expansion system

Abstract

The utility model discloses a multi-outdoor-unit direct expansion system, which relates to the technical field of air conditioners and comprises a first outdoor unit, a second outdoor unit, a third outdoor unit, a first indoor unit coil pipe, a second indoor unit coil pipe, a third indoor unit coil pipe, an air pipe header pipe and a liquid pipe header pipe. The first indoor unit coil pipe, the second indoor unit coil pipe and the third indoor unit coil pipe are each provided with a connecting air pipe assembly and a connecting liquid pipe assembly. The device has the beneficial effects that air guide assemblies on the first outdoor unit, the second outdoor unit and the third outdoor unit are connected with air pipe connecting assemblies on the first indoor unit coil pipe, the second indoor unit coil pipe and the third indoor unit coil pipe through the Y-shaped branch pipe, the air pipe header pipe and the liquid pipe header pipe respectively in a pipe combining mode, and liquid guide assemblies and liquid pipe connecting assemblies on the first indoor unit coil pipe, the second indoor unit coil pipe and the third indoor unit coil pipe are connected in a pipe combining mode; the connecting number and length of the pipelines are greatly reduced, the possibility of errors during butt joint of the connecting pipes is greatly reduced, and operation convenience and connecting accuracy are improved.

Description

Technical Field

[0001] This utility model relates to the field of air conditioner technology, and in particular to a multi-outdoor unit direct expansion system. Background Technology

[0002] Currently, the connecting pipes between the indoor and outdoor units of split-type air-cooled unit air conditioners are connected according to the system correspondence: that is, the coil system corresponds to the outdoor unit system, and the gas and liquid pipes of the indoor and outdoor units are connected in a corresponding manner.

[0003] Compared with existing technologies, this connection method results in a bloated and complex piping system when multiple indoor and outdoor unit systems are involved, leading to a longer installation cycle, higher installation costs, and an increased error rate in pipe connection. Therefore, improvements are needed to the piping connection of existing multi-outdoor unit direct expansion systems. Utility Model Content

[0004] The purpose of this invention is to provide a multi-external-unit direct expansion system in order to solve the above-mentioned problems.

[0005] This utility model achieves the above objectives through the following technical solutions:

[0006] A multi-outdoor unit direct expansion system includes a first outdoor unit, a second outdoor unit, a third outdoor unit, a first indoor unit coil, a second indoor unit coil, a third indoor unit coil, a gas pipe main, and a liquid pipe main. Each of the first, second, and third outdoor units is equipped with a gas guide assembly and a liquid guide assembly. Each of the first, second, and third indoor unit coils is equipped with a connecting gas pipe assembly and a connecting liquid pipe assembly. Each of the gas guide assembly, liquid guide assembly, connecting gas pipe assembly, and connecting liquid pipe assembly is equipped with a control valve group for on / off control. The gas guide assembly and connecting gas pipe assembly are respectively connected to both ends of the gas pipe main, and the liquid guide assembly and connecting liquid pipe assembly are respectively connected to both ends of the liquid pipe main.

[0007] Furthermore, the air guiding assembly includes a first outdoor unit air pipe, a second outdoor unit air pipe, a third outdoor unit air pipe, and a Y-shaped branch pipe. The first outdoor unit air pipe is connected to the first outdoor unit, the second outdoor unit air pipe is connected to the second outdoor unit, and the third outdoor unit air pipe is connected to the third outdoor unit. The first outdoor unit air pipe and the second outdoor unit air pipe, as well as the second outdoor unit air pipe and the third outdoor unit air pipe, are each connected to the same Y-shaped branch pipe. The Y-shaped branch pipes on the first outdoor unit air pipe and the second outdoor unit air pipe, as well as the Y-shaped branch pipes on the second outdoor unit air pipe and the third outdoor unit air pipe, are all connected to one end of the main air pipe.

[0008] Furthermore, the liquid guiding assembly includes a first outdoor unit liquid pipe, a second outdoor unit liquid pipe, and a third outdoor unit liquid pipe. The first outdoor unit liquid pipe is connected to the first outdoor unit, the second outdoor unit liquid pipe is connected to the second outdoor unit, and the third outdoor unit liquid pipe is connected to the third outdoor unit. The first outdoor unit liquid pipe and the second outdoor unit liquid pipe, as well as the second outdoor unit liquid pipe and the third outdoor unit liquid pipe, are each connected to the same Y-shaped branch pipe. The Y-shaped branch pipes on the first outdoor unit liquid pipe and the second outdoor unit liquid pipe, as well as the Y-shaped branch pipes on the second outdoor unit liquid pipe and the third outdoor unit liquid pipe, are all connected to one end of the main liquid pipe.

[0009] Furthermore, the connecting air pipe assembly includes a first coil air pipe, a second coil air pipe, and a third coil air pipe. The first coil air pipe is connected to the first indoor unit coil, the second coil air pipe is connected to the second indoor unit coil, and the third coil air pipe is connected to the third indoor unit coil. The first coil air pipe and the second coil air pipe, as well as the second coil air pipe and the third coil air pipe, are each connected to the same Y-shaped branch pipe. The Y-shaped branch pipes on the first coil air pipe and the second coil air pipe, as well as the Y-shaped branch pipes on the second coil air pipe and the third coil air pipe, are all connected to one end of the main air pipe.

[0010] Furthermore, the connecting liquid pipe assembly includes a first coil liquid pipe, a second coil liquid pipe, and a third coil liquid pipe. The first coil liquid pipe is connected to a first indoor unit coil, the second coil liquid pipe is connected to a second indoor unit coil, and the third coil liquid pipe is connected to a third indoor unit coil. The first coil liquid pipe and the second coil liquid pipe, as well as the second coil liquid pipe and the third coil liquid pipe, are each connected to the same Y-shaped branch pipe. The Y-shaped branch pipes on the first coil liquid pipe and the second coil liquid pipe, as well as the Y-shaped branch pipes on the second coil liquid pipe and the third coil liquid pipe, are all connected to one end of the main liquid pipe.

[0011] Furthermore, the control valve assembly includes electric ball valves and manual ball valves, which are arranged in an orderly manner and connected to the first outdoor unit air pipe, the second outdoor unit air pipe, the third outdoor unit air pipe, the first outdoor unit liquid pipe, the second outdoor unit liquid pipe, the third outdoor unit liquid pipe, the first coil air pipe, the second coil air pipe, the third coil air pipe, the first coil liquid pipe, the second coil liquid pipe, and the third coil liquid pipe, respectively.

[0012] Furthermore, electric ball valves and manual ball valves are installed between the first outdoor unit, the second outdoor unit, the third outdoor unit, the first indoor unit coil, the second indoor unit coil, the third indoor unit coil, and the Y-type branch pipe.

[0013] The advantages compared to existing technologies are as follows:

[0014] 1. By using Y-shaped branch pipes, gas main pipes, and liquid main pipes, the air guiding components on the first, second, and third outdoor units are connected to the connecting gas pipe components, liquid guiding components, and connecting liquid pipe components on the first, second, and third indoor unit coils, respectively. This greatly reduces the number and length of pipe connections, reduces the possibility of errors during pipe connection, and improves the convenience of operation and the accuracy of connection.

[0015] 2. Different outdoor units can be started and stopped independently through electric ball valves and manual ball valves. The number of outdoor units operating can be controlled as needed, reducing resource waste and greatly improving the adaptability and environmental protection requirements of the unit. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the overall structure of a multi-outdoor direct expansion system described in this utility model.

[0018] The annotations in the attached figures are explained as follows:

[0019] 1. First outdoor unit; 2. Second outdoor unit; 3. Third outdoor unit; 4. First indoor unit coil; 5. Second indoor unit coil; 6. Third indoor unit coil; 7. Y-type branch pipe; 8. Electric ball valve; 9. Manual ball valve; 10. First coil gas pipe; 11. First coil liquid pipe; 12. Second coil gas pipe; 13. Second coil liquid pipe; 14. Third coil gas pipe; 15. Third coil liquid pipe; 16. First outdoor unit gas pipe; 17. First outdoor unit liquid pipe; 18. Second outdoor unit gas pipe; 19. Second outdoor unit liquid pipe; 20. Third outdoor unit gas pipe; 21. Third outdoor unit liquid pipe; 22. Gas main pipe; 23. Liquid main pipe. Detailed Implementation

[0020] like Figure 1As shown, a multi-outdoor unit direct expansion system includes a first outdoor unit 1, a second outdoor unit 2, a third outdoor unit 3, a first indoor unit coil 4, a second indoor unit coil 5, a third indoor unit coil 6, a gas main pipe 22, and a liquid main pipe 23, all fixed in parallel. Gas guide components and liquid guide components are fixedly installed on the first outdoor unit 1, the second outdoor unit 2, and the third outdoor unit 3. Gas connection components and liquid connection components are fixedly installed on the first indoor unit coil 4, the second indoor unit coil 5, and the third indoor unit coil 6. Control valve assemblies for controlling the on / off state are fixedly installed on the gas guide components, liquid guide components, gas connection components, and liquid connection components. The gas guide components and gas connection components are respectively fixedly connected to both ends of the gas main pipe 22, and the liquid guide components and liquid connection components are respectively fixedly connected to both ends of the liquid main pipe 23. The gas main pipe 22 connects the gas guide components on the first outdoor unit 1, the second outdoor unit 2, and the third outdoor unit 3 to the first indoor unit coil 4. The connecting air pipe assemblies on the second indoor unit coil 5 and the third indoor unit coil 6 are connected. The liquid guiding assemblies on the first outdoor unit 1, the second outdoor unit 2, and the third outdoor unit 3 are connected to the connecting liquid pipe assemblies on the first indoor unit coil 4, the second indoor unit coil 5, and the third indoor unit coil 6 through the liquid pipe main 23. This completes the parallel pipe operation of the air guiding assembly, the air pipe main 22, and the connecting air pipe assembly, as well as the parallel pipe operation of the liquid guiding assembly, the liquid pipe main 23, and the connecting liquid pipe assembly. This reduces the length of the air guiding assembly, the connecting air pipe assembly, the liquid guiding assembly, and the connecting liquid pipe assembly, improving the convenience of operation and pipe connection. It greatly reduces the number of pipe connections and the possibility of errors during connection. Furthermore, the control valve group can realize the individual control of different outdoor units. It can control the first outdoor unit 1, the second outdoor unit 2, and the third outdoor unit 3 to work as needed, reducing resource waste and greatly improving the adaptability and environmental protection requirements of the unit.

[0021] like Figure 1As shown, the air guiding assembly includes a first outdoor unit air pipe 16, a second outdoor unit air pipe 18, a third outdoor unit air pipe 20, and a Y-shaped branch pipe 7. The first outdoor unit air pipe 16 is fixedly connected to the first outdoor unit 1, the second outdoor unit air pipe 18 is fixedly connected to the second outdoor unit 2, and the third outdoor unit air pipe 20 is fixedly connected to the third outdoor unit 3. The first outdoor unit air pipe 16 and the second outdoor unit air pipe 18, the second outdoor unit air pipe 18, and the third outdoor unit air pipe 20 are each connected to the same Y-shaped branch pipe 7. The Y-shaped branch pipe 7 on the first outdoor unit air pipe 16 and the second outdoor unit air pipe 18 is connected to the second outdoor unit air pipe 18. The Y-shaped branch pipes 7 on the third outdoor unit air pipe 20 are all fixedly connected to one end of the main air pipe 22. The first outdoor unit air pipe 16 and the second outdoor unit air pipe 18 are connected by the two Y-shaped branch pipes 7 respectively, and the second outdoor unit air pipe 18 and the third outdoor unit air pipe 20 are connected. This allows the first outdoor unit air pipe 16, the second outdoor unit air pipe 18, and the third outdoor unit air pipe 20 to be connected in parallel, reducing the length of the first outdoor unit air pipe 16, the second outdoor unit air pipe 18, and the third outdoor unit air pipe 20, improving the convenience of operation, facilitating connection operation, and reducing the possibility of errors during connection.

[0022] like Figure 1 As shown, the liquid guiding assembly includes a first outdoor unit liquid pipe 17, a second outdoor unit liquid pipe 19, and a third outdoor unit liquid pipe 21. The first outdoor unit liquid pipe 17 is fixedly connected to the first outdoor unit 1, the second outdoor unit liquid pipe 19 is fixedly connected to the second outdoor unit 2, and the third outdoor unit liquid pipe 21 is fixedly connected to the third outdoor unit 3. The first outdoor unit liquid pipe 17 and the second outdoor unit liquid pipe 19, the second outdoor unit liquid pipe 19, and the third outdoor unit liquid pipe 21 are each connected to the same Y-shaped branch pipe 7. The Y-shaped branch pipes 7 on the first outdoor unit liquid pipe 17 and the second outdoor unit liquid pipe 19 are connected to the Y-shaped branch pipes 7 on the second outdoor unit liquid pipe 19 and the third outdoor unit liquid pipe 21. Each manifold 7 is fixedly connected to one end of the main liquid pipe 23. The first outdoor unit liquid pipe 17 and the second outdoor unit liquid pipe 19 are connected by two Y-shaped branch pipes 7 respectively. The second outdoor unit liquid pipe 19 and the third outdoor unit liquid pipe 21 are connected and directly connected to the main liquid pipe 23 through the Y-shaped branch pipes 7. This allows the first outdoor unit liquid pipe 17, the second outdoor unit liquid pipe 19, and the third outdoor unit liquid pipe 21 to be connected in parallel, reducing the length of the first outdoor unit liquid pipe 17, the second outdoor unit liquid pipe 19, and the third outdoor unit liquid pipe 21, improving the convenience of operation, facilitating connection operations, and reducing the possibility of errors during connection.

[0023] like Figure 1As shown, the connecting tubing assembly includes a first coil tubing 10, a second coil tubing 12, and a third coil tubing 14. The first coil tubing 10 is fixedly connected to the first indoor unit coil 4, the second coil tubing 12 is fixedly connected to the second indoor unit coil 5, and the third coil tubing 14 is fixedly connected to the third indoor unit coil 6. The first coil tubing 10, the second coil tubing 12, the second coil tubing 12, and the third coil tubing 14 are each connected to the same Y-shaped branch pipe 7. The Y-shaped branch pipes 7 on the first coil tubing 10 and the second coil tubing 12 are connected to the second coil tubing 12 and the third coil tubing 14. The Y-shaped branch pipes 7 are all fixedly connected to one end of the main tracheal tube 22. The first coil tracheal tube 10 and the second coil tracheal tube 12 are connected by the two Y-shaped branch pipes 7 respectively, and the second coil tracheal tube 12 and the third coil tracheal tube 14 are connected. They are directly connected to the main tracheal tube 22 through the Y-shaped branch pipes 7, so that the first coil tracheal tube 10, the second coil tracheal tube 12 and the third coil tracheal tube 14 are connected in parallel, which reduces the length of the first coil tracheal tube 10, the second coil tracheal tube 12 and the third coil tracheal tube 14, improves the convenience of operation, facilitates connection operation, and reduces the possibility of errors during connection.

[0024] like Figure 1 As shown, the connecting liquid pipe assembly includes a first coil liquid pipe 11, a second coil liquid pipe 13, and a third coil liquid pipe 15. The first coil liquid pipe 11 is fixedly connected to the first indoor unit coil 4, the second coil liquid pipe 13 is fixedly connected to the second indoor unit coil 5, and the third coil liquid pipe 15 is fixedly connected to the third indoor unit coil 6. The first coil liquid pipe 11, the second coil liquid pipe 13, and the third coil liquid pipe 15 are each connected to the same Y-shaped branch pipe 7. The Y-shaped branch pipes 7 on the first coil liquid pipe 11 and the second coil liquid pipe 13 are connected to the second coil liquid pipe 13 and the third coil liquid pipe 15. The Y-shaped branch pipes 7 on the 5 are all fixedly connected to one end of the main liquid pipe 23. The first coil liquid pipe 11 and the second coil liquid pipe 13 are connected through the two Y-shaped branch pipes 7 respectively, and the second coil liquid pipe 13 and the third coil liquid pipe 15 are connected. They are directly connected to the main liquid pipe 23 through the Y-shaped branch pipes 7, so that the first coil liquid pipe 11, the second coil liquid pipe 13 and the third coil liquid pipe 15 are connected in parallel, reducing the length of the first coil liquid pipe 11, the second coil liquid pipe 13 and the third coil liquid pipe 15, improving the convenience of operation, facilitating connection operation, and reducing the possibility of errors during connection.

[0025] like Figure 1As shown, the control valve assembly includes an electric ball valve 8 and a manual ball valve 9, which are arranged in a row. The electric ball valve 8 and the manual ball valve 9 are respectively fixedly connected to the first outdoor unit air pipe 16, the second outdoor unit air pipe 18, the third outdoor unit air pipe 20, the first outdoor unit liquid pipe 17, the second outdoor unit liquid pipe 19, the third outdoor unit liquid pipe 21, the first coil air pipe 10, the second coil air pipe 12, the third coil air pipe 14, the first coil liquid pipe 11, the second coil liquid pipe 13, and the third coil liquid pipe 15. The electric ball valve 8 and the manual ball valve 9 are installed on the first... The outdoor unit 1, the second outdoor unit 2, the third outdoor unit 3, the first indoor unit coil 4, the second indoor unit coil 5, the third indoor unit coil 6, and the Y-type branch pipe 7 are connected by electric ball valves 8 and manual ball valves 9 to facilitate the start-up and shutdown of different outdoor units. The electric ball valves 8 and manual ball valves 9 increase the safety of operation. When the cooling demand is relatively small, the electric ball valves 8 and manual ball valves 9 can be used to control the operation of different outdoor units separately, preventing the flowing refrigerant from entering the pipeline, reducing resource waste, and greatly improving the adaptability and environmental protection requirements of the unit.

[0026] Working principle: such as Figure 1 As shown, the first outdoor unit air pipe 16 and the second outdoor unit air pipe 18 are connected by the Y-shaped branch pipe 7, and the second outdoor unit air pipe 18 and the third outdoor unit air pipe 20 are connected, so that the first outdoor unit air pipe 16, the second outdoor unit air pipe 18 and the third outdoor unit air pipe 20 are connected to each other in parallel, and are connected to the main air pipe 22 by the Y-shaped branch pipe 7.

[0027] like Figure 1 As shown, the first outdoor unit liquid pipe 17 and the second outdoor unit liquid pipe 19 are connected by the Y-type branch pipe 7, and the second outdoor unit liquid pipe 19 and the third outdoor unit liquid pipe 21 are connected, so that the first outdoor unit liquid pipe 17, the second outdoor unit liquid pipe 19 and the third outdoor unit liquid pipe 21 are connected in parallel, and the Y-type branch pipe 7 is connected to the main liquid pipe 23.

[0028] like Figure 1 As shown, the first coil air pipe 10 and the second coil air pipe 12 are connected by the Y-shaped branch pipe 7, and the second coil air pipe 12 and the third coil air pipe 14 are connected, so that the first coil air pipe 10, the second coil air pipe 12 and the third coil air pipe 14 are connected in parallel, and are connected to the main air pipe 22 by the Y-shaped branch pipe 7.

[0029] like Figure 1 As shown, the first coil liquid pipe 11 and the second coil liquid pipe 13 are connected by the Y-shaped branch pipe 7, and the second coil liquid pipe 13 and the third coil liquid pipe 15 are connected, so that the first coil liquid pipe 11, the second coil liquid pipe 13 and the third coil liquid pipe 15 are connected in parallel, and the Y-shaped branch pipe 7 is connected to the main liquid pipe 23.

[0030] like Figure 1 As shown, the pipes on the parallel outdoor and indoor units are connected by two pipes, gas main pipe 22 and liquid main pipe 23, which greatly reduces the number and length of pipe connections and reduces the possibility of pipe connection errors.

[0031] like Figure 1 As shown, different outdoor units can be controlled by electric ball valve 8 and manual ball valve 9. When the cooling demand is relatively small, different outdoor units can be controlled separately by electric ball valve 8 and manual ball valve 9 to prevent flowing refrigerant from entering the pipeline, reduce resource waste, and greatly improve the adaptability and environmental protection requirements of the unit.

[0032] The foregoing has shown and described the basic principles, main features, and advantages of this utility model. Those skilled in the art should understand that this utility model is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of this utility model. Various changes and modifications can be made to this utility model without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed utility model.

Claims

1. A multiple outdoor unit direct expansion system, characterized by, The system includes a first outdoor unit (1), a second outdoor unit (2), a third outdoor unit (3), a first indoor unit coil (4), a second indoor unit coil (5), a third indoor unit coil (6), a gas main pipe (22), and a liquid main pipe (23) arranged in parallel. Each of the first outdoor unit (1), the second outdoor unit (2), and the third outdoor unit (3) is equipped with a gas guide assembly and a liquid guide assembly. Each of the first indoor unit coil (4), the second indoor unit coil (5), and the third indoor unit coil (6) is equipped with a gas connection assembly and a liquid connection assembly. Each of the gas guide assembly, the liquid guide assembly, the gas connection assembly, and the liquid connection assembly is equipped with a control valve group for controlling the on / off state. The gas guide assembly and the gas connection assembly are respectively connected to both ends of the gas main pipe (22), and the liquid guide assembly and the liquid connection assembly are respectively connected to both ends of the liquid main pipe (23).

2. A multiple outdoor unit direct expansion system as set forth in claim 1, wherein: The air guiding assembly includes a first outdoor unit air pipe (16), a second outdoor unit air pipe (18), a third outdoor unit air pipe (20), and a Y-shaped branch pipe (7). The first outdoor unit air pipe (16) is connected to the first outdoor unit (1), the second outdoor unit air pipe (18) is connected to the second outdoor unit (2), and the third outdoor unit air pipe (20) is connected to the third outdoor unit (3). The first outdoor unit air pipe (16) and the second outdoor unit air pipe (18), as well as the second outdoor unit air pipe (18) and the third outdoor unit air pipe (20), are respectively connected to the same Y-shaped branch pipe (7). The Y-shaped branch pipe (7) on the first outdoor unit air pipe (16) and the second outdoor unit air pipe (18), as well as the Y-shaped branch pipe (7) on the second outdoor unit air pipe (18) and the third outdoor unit air pipe (20), are all connected to one end of the main air pipe (22).

3. A multiple outdoor unit direct expansion system as set forth in claim 2, wherein: The liquid guiding assembly includes a first outdoor unit liquid pipe (17), a second outdoor unit liquid pipe (19), and a third outdoor unit liquid pipe (21). The first outdoor unit liquid pipe (17) is connected to the first outdoor unit (1), the second outdoor unit liquid pipe (19) is connected to the second outdoor unit (2), and the third outdoor unit liquid pipe (21) is connected to the third outdoor unit (3). The first outdoor unit liquid pipe (17) and the second outdoor unit liquid pipe (19), as well as the second outdoor unit liquid pipe (19) and the third outdoor unit liquid pipe (21), are respectively connected to the same Y-shaped branch pipe (7). The Y-shaped branch pipe (7) on the first outdoor unit liquid pipe (17) and the second outdoor unit liquid pipe (19), as well as the Y-shaped branch pipe (7) on the second outdoor unit liquid pipe (19) and the third outdoor unit liquid pipe (21), are all connected to one end of the main liquid pipe (23).

4. A multiple outdoor unit direct expansion system as set forth in claim 3, wherein: The connecting air pipe assembly includes a first coil air pipe (10), a second coil air pipe (12), and a third coil air pipe (14). The first coil air pipe (10) is connected to the first indoor unit coil (4), the second coil air pipe (12) is connected to the second indoor unit coil (5), and the third coil air pipe (14) is connected to the third indoor unit coil (6). The first coil air pipe (10) and the second coil air pipe (12), as well as the second coil air pipe (12) and the third coil air pipe (14), are respectively connected to the same Y-shaped branch pipe (7). The Y-shaped branch pipe (7) on the first coil air pipe (10) and the second coil air pipe (12), as well as the Y-shaped branch pipe (7) on the second coil air pipe (12) and the third coil air pipe (14), are all connected to one end of the main air pipe (22).

5. A multiple outdoor unit direct expansion system as set forth in claim 4, wherein: The connecting liquid pipe assembly includes a first coil liquid pipe (11), a second coil liquid pipe (13), and a third coil liquid pipe (15). The first coil liquid pipe (11) is connected to the first indoor unit coil (4), the second coil liquid pipe (13) is connected to the second indoor unit coil (5), and the third coil liquid pipe (15) is connected to the third indoor unit coil (6). The first coil liquid pipe (11) and the second coil liquid pipe (13), as well as the second coil liquid pipe (13) and the third coil liquid pipe (15), are respectively connected to the same Y-shaped branch pipe (7). The Y-shaped branch pipe (7) on the first coil liquid pipe (11) and the second coil liquid pipe (13), as well as the Y-shaped branch pipe (7) on the second coil liquid pipe (13) and the third coil liquid pipe (15), are all connected to one end of the liquid pipe main pipe (23).

6. A multiple outdoor unit direct expansion system as set forth in claim 5, wherein: The control valve group includes an electric ball valve (8) and a manual ball valve (9). The electric ball valve (8) and the manual ball valve (9) are arranged in a row. The electric ball valve (8) and the manual ball valve (9) are respectively connected to the first outdoor unit air pipe (16), the second outdoor unit air pipe (18), the third outdoor unit air pipe (20), the first outdoor unit liquid pipe (17), the second outdoor unit liquid pipe (19), the third outdoor unit liquid pipe (21), the first coil air pipe (10), the second coil air pipe (12), the third coil air pipe (14), the first coil liquid pipe (11), the second coil liquid pipe (13), and the third coil liquid pipe (15).

7. A multiple outdoor unit direct expansion system as set forth in claim 6, wherein: The electric ball valve (8) and the manual ball valve (9) are installed between the first outdoor unit (1), the second outdoor unit (2), the third outdoor unit (3), the first indoor unit coil (4), the second indoor unit coil (5), the third indoor unit coil (6), and the Y-type branch pipe (7).

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