Three-pipe multi-split air conditioning system

Abstract

The utility model provides a three-pipe multi-split air conditioning system. The three-pipe multi-split air conditioning system comprises an outdoor unit, an indoor unit, a dehumidifier, a first four-way valve and a second four-way valve, the indoor unit and the dehumidifier are arranged in parallel. The outdoor unit is connected with the indoor unit through a first four-way valve. The outdoor unit is connected with the dehumidifier through the first four-way valve and the second four-way valve. By arranging the first four-way valve and the second four-way valve, effective control over the indoor unit and the dehumidifier can be achieved. And meanwhile, the indoor unit and the dehumidifier are arranged in parallel, so that the system can flexibly switch different operation modes, and the refrigerating and heating efficiency of the system is improved.

Description

Technical Field

[0001] This application relates to the field of air conditioning, and in particular to three-pipe multi-split systems. Background Technology

[0002] With the continuous improvement of people's living standards, air conditioning systems are installed in residential or working environments to enhance comfort. Among these, three-pipe multi-split systems are an important direction for air conditioning development due to their advantages such as flexible control, high efficiency and energy saving, and ease of installation and maintenance. Three-pipe multi-split systems are mainly used to control indoor temperature and humidity, and generally include one or more outdoor units, a dehumidifier, and indoor units. A three-pipe multi-split system can operate with a single indoor unit running, or multiple indoor units can be started simultaneously, making control more flexible. Currently, three-pipe multi-split systems on the market only have one four-way valve. When other indoor units are cooling and one indoor unit is heating, the dehumidifier cannot dehumidify without lowering the temperature, resulting in lower cooling or heating efficiency for the three-pipe multi-split system.

[0003] Therefore, it is necessary to provide an improved three-pipe multi-split air conditioning system to solve the above problems. Utility Model Content

[0004] This application provides a three-pipe multi-split air conditioning system that can improve cooling or heating efficiency.

[0005] This application provides a three-pipe multi-split air conditioning system, including an outdoor unit, an indoor unit, a dehumidifier, and a first four-way valve and a second four-way valve arranged in parallel; the indoor unit and the dehumidifier are arranged in parallel; the outdoor unit and the indoor unit are connected through the first four-way valve; the outdoor unit and the dehumidifier are connected through the first four-way valve and the second four-way valve.

[0006] Furthermore, the indoor unit and the dehumidifier are respectively connected to a liquid-side shut-off valve and a gas-side shut-off valve at both ends; both the liquid-side shut-off valve and the gas-side shut-off valve are connected to the first four-way valve; a high-low pressure shut-off valve is connected between the dehumidifier and the outdoor unit, and the high-low pressure shut-off valve is connected to the second four-way valve.

[0007] Furthermore, the indoor unit includes an indoor unit heat exchanger and a first electronic expansion valve connected in series. One end of the indoor unit heat exchanger is connected to the gas-side shut-off valve, and one end of the first electronic expansion valve is connected to the liquid-side shut-off valve. An air conditioning coil and an auxiliary coil are connected in parallel inside the dehumidifier. Both the air conditioning coil and the auxiliary coil are connected to electronic expansion valves. One end of the electronic expansion valve is connected to the liquid-side shut-off valve. One end of the air conditioning coil is connected to the gas-side shut-off valve. One end of the auxiliary coil is connected to the high and low pressure shut-off valves.

[0008] Furthermore, the three-pipe multi-split air conditioning system also includes a connecting valve, which has four ports connected sequentially by pipes. The four ports are respectively connected to the gas-side shut-off valve, the air conditioning coil, the high and low pressure shut-off valve, and the auxiliary coil. The connecting valve is equipped with four on / off switches, which are located between two adjacent ports.

[0009] Furthermore, the outdoor unit includes a compressor, an oil separator, a gas-liquid separator, and an outdoor unit heat exchanger; the exhaust port of the compressor is connected to the inlet of the oil separator, and the outlet of the oil separator is connected to the first four-way valve; the inlet of the gas-liquid separator is connected to the first four-way valve and the second four-way valve, and the outlet of the gas-liquid separator is connected to the inlet of the compressor; both ends of the outdoor unit heat exchanger are respectively connected to the first four-way valve and the liquid-side shut-off valve.

[0010] Furthermore, the first four-way valve includes an A port, a B port, a C port, and a D port; the second four-way valve includes an A1 port, a B1 port, a C1 port, and a D1 port; the D port and the D1 port are connected to the air outlet of the oil separator; the D port is connected to the D1 port, and the B port is connected to the B1 port.

[0011] Furthermore, the A interface is switched to be connected to the B interface and the D interface; the C interface is switched to be connected to the B interface and the D interface; the A1 interface is connected to the B1 interface and / or the D1 interface; and the C1 interface is switched to be connected to the B1 interface and the D1 interface.

[0012] Furthermore, a low-pressure sensor is provided between the air inlet of the compressor and the air outlet of the gas-liquid separator; an exhaust check valve and a high-pressure sensor are provided at the air outlet of the oil separator; and an exhaust temperature sensor and a high-pressure switch are provided at the air outlet of the compressor.

[0013] Furthermore, the four on / off switches are respectively a first switch, a second switch, a third switch, and a fourth switch; the four interfaces are respectively an E interface, an F interface, a G interface, and an H interface; the first switch is located between the F interface and the G interface; the second switch is located between the E interface and the F interface; the third switch is located between the E interface and the H interface; and the fourth switch is located between the G interface and the H interface.

[0014] Furthermore, when the three-pipe multi-split air conditioning system is in cooling mode, the A interface is connected to the D interface, the B interface is connected to the C interface; the A1 interface is connected to the B1 interface and the D1 interface, and the B1 interface is connected to the C1 interface; the second switch and the third switch are open, and the first switch and the fourth switch are closed.

[0015] Furthermore, when the three-pipe multi-split system is in main cooling mode, the A interface is connected to the D interface, the B interface is connected to the C interface; the A1 interface is connected to the B1 interface, and the C1 interface is connected to the D1 interface; the second switch and the fourth switch are open, and the first switch and the third switch are closed.

[0016] Furthermore, when the three-pipe multi-split air conditioning system is in heating mode, the A port is connected to the B port, and the C port is connected to the D port; the A1 port is connected to the B1 port and the D1 port, and the B1 port is connected to the C1 port; the second switch and the third switch are open, and the first switch and the fourth switch are closed.

[0017] Furthermore, when the three-pipe multi-split system is in main heating mode, the A port is connected to the B port, and the C port is connected to the D port; the A1 port is connected to the B1 port and the D1 port, and the B1 port is connected to the C1 port; the first switch and the third switch are open, and the second switch and the fourth switch are closed.

[0018] This application achieves effective control of the indoor unit and dehumidifier by setting up a first four-way valve and a second four-way valve. Simultaneously, the parallel connection of the indoor unit and dehumidifier allows the system to flexibly switch between different operating modes, thereby improving the system's cooling and heating efficiency. Attached Figure Description

[0019] Figure 1 This is a connection diagram of the three-pipe multi-split air conditioning system of this application in cooling mode.

[0020] Figure 2 This is a connection diagram of a three-pipe multi-split air conditioning system in main cooling mode.

[0021] Figure 3 This is a connection diagram of a three-pipe multi-split air conditioning system in heating mode.

[0022] Figure 4 This is a connection diagram of a three-pipe multi-split air conditioning system in main heating mode.

[0023] Figure 5 This is a structural diagram of a dehumidifier in a three-pipe multi-split air conditioning system.

[0024] Figure 6 This is a schematic diagram of the connection valve of the three-pipe multi-split air conditioning system of this application in cooling mode.

[0025] Figure 7 This is a connection diagram of the connecting valve in the main cooling mode.

[0026] Figure 8 This is a connection diagram of the connecting valve in heating mode.

[0027] Figure 9 This is a connection diagram of the connecting valve in the main heating mode.

[0028] Explanation of icon numbers

[0029] 10. Outdoor unit; 11. Compressor; 12. Oil separator; 121. First filter; 122. Capillary tube; 13. Gas-liquid separator; 131. Intake temperature sensor; 14. Outdoor unit heat exchanger; 141. Fan assembly; 142. Main expansion valve; 143. Second filter; 15. Low-pressure sensor; 16. Exhaust check valve; 17. High-pressure sensor; 18. Exhaust temperature sensor; 19. High-pressure switch; 20. Indoor unit; 21. Indoor unit heat exchanger Heater; 22, First electronic expansion valve; 30, Dehumidifier; 31, Air conditioning coil; 32, Auxiliary coil; 33, Electronic expansion valve; 40, First four-way valve; 50, Second four-way valve; 60, Liquid-side shut-off valve; 61, First main filter; 70, Gas-side shut-off valve; 71, Second main filter; 80, High and low pressure shut-off valves; 81, Third main filter; 90, Connecting valve; 91, First switch; 92, Second switch; 93, Third switch; 94, Fourth switch. Detailed Implementation

[0030] The technical solutions in the embodiments (or "implementations") of this application will be clearly and completely described herein with reference to the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements.

[0031] If the embodiments of this application contain terms relating to directional indications or positional relationships (such as up, down, left, right, front, back, inside, outside, top, bottom, center, vertical, horizontal, longitudinal, transverse, length, width, counterclockwise, clockwise, axial, radial, circumferential, etc.), such terms are only used to explain the relative positional relationships and movements between components in a specific posture (as shown in the attached figures); if the specific posture changes, the directional indications or positional relationships will also change accordingly. Furthermore, the terms "first" and "second" used in the embodiments of this application are only for descriptive convenience and should not be construed as indicating or implying relative importance.

[0032] See Figures 1 to 4 As shown, this application provides a three-pipe multi-split air conditioning system, including an outdoor unit 10, an indoor unit 20, a dehumidifier 30, a first four-way valve 40, and a second four-way valve 50. The outdoor unit 10 and the indoor unit 20 are connected via the first four-way valve 40. The outdoor unit 10 and the dehumidifier 30 are connected via both the first four-way valve 40 and the second four-way valve 50. The indoor unit 20 and the dehumidifier 30 are connected in parallel. The first four-way valve 40 and the second four-way valve 50 are connected in parallel.

[0033] The three-pipe multi-split air conditioning system also includes a liquid-side shut-off valve 60, an air-side shut-off valve 70, and a high / low pressure shut-off valve 80. The indoor unit 20 and the dehumidifier 30 are respectively connected to the liquid-side shut-off valve 60 and the air-side shut-off valve 70 at both ends. The liquid-side shut-off valve 60 is connected to the outdoor unit 10. The air-side shut-off valve 70 is connected to the first four-way valve 40. The dehumidifier 30 is connected to the liquid-side shut-off valve 60, the air-side shut-off valve 70, and the high / low pressure shut-off valve 80. The high / low pressure shut-off valve 80 is connected to the second four-way valve 50.

[0034] The outdoor unit 10 includes a compressor 11, an oil separator 12, a gas-liquid separator 13, an outdoor unit heat exchanger 14, a low-pressure sensor 15, an exhaust check valve 16, a high-pressure sensor 17, an exhaust temperature sensor 18, and a high-pressure switch 19. The exhaust port of the compressor 11 is connected to the inlet of the oil separator 12, and the outlet of the oil separator 12 is connected to a first four-way valve 40. The exhaust check valve 16 is located between the oil separator 12 and the first four-way valve 40. The outlet of the oil separator 12 is connected to the inlet of the exhaust check valve 16, and the outlet of the exhaust check valve 16 is connected to the first four-way valve 40. A first filter 121 is provided at the inlet of the oil separator 12 to preliminarily filter the medium entering the oil separator 12. The pipe connecting the first filter 121 to the compressor 11 and the gas-liquid separator 13 is connected via a capillary tube 122.

[0035] A high-pressure sensor 17 is located between the exhaust check valve 16 and the first four-way valve 40 to monitor the pressure at the inlet of the first four-way valve 40 in real time. The inlet of the gas-liquid separator 13 is connected to the first four-way valve 40 and the second four-way valve 50, and the outlet of the gas-liquid separator 13 is connected to the inlet of the compressor 11 and the inlet of the oil separator 12. A suction temperature sensor 131 is provided at the inlet of the gas-liquid separator 13 to detect the temperature at the inlet of the gas-liquid separator 13 in real time.

[0036] The outdoor unit heat exchanger 14 is connected at both ends to a first four-way valve 40 and a liquid-side shut-off valve 60, respectively. A fan assembly 141 is provided at the outdoor unit heat exchanger 14 for cooling the outdoor unit heat exchanger 14. A main expansion valve 142 is provided between the outdoor unit heat exchanger 14 and the liquid-side shut-off valve 60. A second filter 143 is provided between the main expansion valve 142 and the outdoor unit heat exchanger 14.

[0037] A low-pressure sensor 15 is located between the inlet of the compressor 11 and the outlet of the gas-liquid separator 13. An exhaust temperature sensor 18 and a high-pressure switch 19 are located at the outlet of the compressor 11. The high-pressure switch 19 is located between the compressor 11 and the oil separator 12. The exhaust temperature sensor 18 monitors the outlet temperature of the compressor 11 in real time. When the outlet temperature or pressure of the compressor 11 is too high, the high-pressure switch 19 controls the compressor 11 to disconnect from the oil separator 12.

[0038] The indoor unit 20 includes an indoor unit heat exchanger 21 and a first electronic expansion valve 22. One end of the indoor unit heat exchanger 21 is connected to the gas-side shut-off valve 70, and the other end of the indoor unit heat exchanger 21 is connected to one end of the first electronic expansion valve 22. The other end of the first electronic expansion valve 22 is connected to the liquid-side shut-off valve 60.

[0039] Please also see Figure 5 As shown, an air conditioning coil 31 and an auxiliary coil 32 are connected in parallel within the dehumidifier 30. Both the air conditioning coil 31 and the auxiliary coil 32 are connected to electronic expansion valves 33. There are two electronic expansion valves 33. One end of the air conditioning coil 31 is connected to the gas-side shut-off valve 70, and the other end of the air conditioning coil 31 is connected to one end of the electronic expansion valve 33. The other end of the electronic expansion valve 33 is connected to the liquid-side shut-off valve 60. One end of the auxiliary coil 32 is connected to the high and low pressure shut-off valves 80, and the other end of the auxiliary coil 32 is connected to the electronic expansion valve 33.

[0040] The first four-way valve 40 includes four ports: A, B, C, and D. The second four-way valve 50 includes four ports: A1, B1, C1, and D1. Ports D and D1 are connected. Ports D and D1 are connected to the outlet of the oil separator 12 via a one-way exhaust valve 16. Ports B and B1 are connected.

[0041] The first four-way valve 40 has its A port switched to be connected to its B and D ports, and its C port switched to be connected to its B and D ports. The second four-way valve 50 has its A1 port always connected to its B1 port. Its A1 port can optionally be connected to its D1 port. Its C1 port can be switched to be connected to its B1 and D1 ports.

[0042] One end of the liquid-side shut-off valve 60 is connected to the first main filter 61, and the other end is connected to the first electronic expansion valve 22 and the electronic expansion valve 33. One end of the gas-side shut-off valve 70 is connected to the second main filter 71, and the other end is connected to the indoor unit heat exchanger 21 and the air conditioning coil 31. One end of the high-low pressure shut-off valve 80 is connected to the third main filter 81, and the other end is connected to the auxiliary coil 32.

[0043] See Figures 6 to 9 As shown, the three-pipe multi-split air conditioning system also includes a connecting valve 90. The connecting valve 90 has four ports connected sequentially via pipes: port E, port F, port G, and port H. Ports E, F, G, and H are connected to the gas-side shut-off valve 70, the air conditioning coil 31, the high and low pressure shut-off valves 80, and the auxiliary coil 32, respectively. The connecting valve 90 is equipped with four on / off switches: switch 91, switch 92, switch 93, and switch 94. One of the on / off switches is located between two adjacent ports.

[0044] According to an embodiment of this application, the first switch 91 is located between the F interface and the G interface. The second switch 92 is located between the E interface and the F interface. The third switch 93 is located between the E interface and the H interface. The fourth switch 94 is located between the G interface and the H interface.

[0045] According to the embodiments of this application, the first switch 91, the second switch 92, the third switch 93, and the fourth switch 94 are all solenoid valves. Alternatively, they may all be electronic expansion valves.

[0046] The control logic of a three-pipe multi-split air conditioning system is as follows: First, the cooling load, heating load, dehumidification load, and reheat load of the system are statistically analyzed. Then, based on the outdoor ambient temperature and humidity, the operating mode of the system is determined. The system has four modes: cooling mode, main cooling mode, heating mode, and main heating mode. Finally, based on the operating mode, the opening and closing of the four switches on the output connecting valve 90 are determined.

[0047] See Figure 1 and Figure 6 As shown, when multiple indoor units 20, air conditioning coils 31, and auxiliary coils 32 are in cooling mode, the three-pipe multi-split system is in cooling mode. The A and D ports of the first four-way valve 40 are connected, and the B and C ports are connected. The A1 port of the second four-way valve 50 is connected to both the B1 and D1 ports, and the B1 port is connected to the C1 port. The second switch 92 and the third switch 93 are open, and the first switch 91 and the fourth switch 94 are closed.

[0048] In cooling mode: After passing through compressor 11, the refrigerant outputs high-temperature, high-pressure gas, which then enters the inlet of oil separator 12 and exits through the outlet of oil separator 12, entering exhaust check valve 16. The refrigerant enters the first four-way valve 40 and the second four-way valve 50 from interfaces D and D1, forming two refrigeration circuits. First refrigeration circuit: The refrigerant flows from interface D to interface A, then into the outdoor unit heat exchanger 14. The refrigerant then passes sequentially through the second filter 143, main expansion valve 142, first main filter 61, and liquid-side shut-off valve 60. After passing through indoor unit 20 and dehumidifier 30, the refrigerant flows to gas-side shut-off valve 70. It then flows from the second main filter 71 to interfaces C and B. Finally, it flows back to compressor 11 through gas-liquid separator 13. Second refrigeration circuit: The refrigerant flows from interface D1 to interfaces A1 and B1. The refrigerant in the high and low pressure pipeline of dehumidifier 30 flows back to interface C1 and then to interface B1. The refrigerant flows from the B1 interface through the gas-liquid separator 13 and finally back to the compressor 11.

[0049] See Figure 2 and Figure 7 As shown, when multiple indoor units 20 and air conditioning coils 31 are in cooling mode, and auxiliary coils 32 are in heating mode, the three-pipe multi-split system is in main cooling mode. The A and D ports of the first four-way valve 40 are connected, and the B and C ports are connected. The A1 and B1 ports of the second four-way valve 50 are connected, and the C1 and D1 ports are connected. The second switch 92 and the fourth switch 94 are open, and the first switch 91 and the third switch 93 are closed.

[0050] In main cooling mode: After passing through compressor 11, the refrigerant outputs high-temperature, high-pressure gas, which then enters the inlet of oil separator 12 and exits through the outlet of oil separator 12, entering exhaust check valve 16. The refrigerant enters the first four-way valve 40 and the second four-way valve 50 from interfaces D and D1, forming two main cooling circuits. First main cooling circuit: The refrigerant flows from interface D to interface A, then into the outdoor unit heat exchanger 14. The refrigerant then passes sequentially through the second filter 143, main expansion valve 142, first main filter 61, and liquid-side shut-off valve 60. After passing through indoor unit 20 and dehumidifier 30, the refrigerant flows to gas-side shut-off valve 70, then from the second main filter 71 to interfaces C and B. Finally, it flows back to compressor 11 through gas-liquid separator 13. Second cooling circuit: The refrigerant flows from interface D1 to interface C1, then through the third main filter 81 and high / low pressure shut-off valve 80. The refrigerant flows through the fourth switch 94, then through the auxiliary coil 32 and the electronic expansion valve 33, then through the air conditioning coil 31 and the second switch 92 to the gas-side shut-off valve 70, and then from the second main filter 71 to the C and B ports. Finally, it flows back to the compressor 11 through the gas-liquid separator 13.

[0051] join Figure 3 and Figure 8 As shown, when multiple indoor units 20, air conditioning coils 31, and auxiliary coils 32 are in heating mode, the three-pipe multi-split system is in heating mode. The A and B ports of the first four-way valve 40 are connected, and the C and D ports are connected. The A1 port of the second four-way valve 50 is connected to both the B1 and D1 ports, and the B1 port is connected to the C1 port. The second switch 92 and the third switch 93 are open, and the first switch 91 and the fourth switch 94 are closed.

[0052] In heating mode: After passing through compressor 11, the refrigerant outputs high-temperature, high-pressure gas, which then enters the inlet of oil separator 12 and exits through the outlet of oil separator 12, entering exhaust check valve 16. The refrigerant enters the first four-way valve 40 and the second four-way valve 50 from interfaces D and D1, forming two heating circuits. First heating circuit: The refrigerant flows from interface D to interface C, then flows into the second main filter 71 and the gas-side shut-off valve 70. The refrigerant flows through indoor unit heat exchanger 21 and air conditioning coil 31, then flows into liquid-side shut-off valve 60 and the first main filter 61. The refrigerant then flows through main expansion valve 142, second filter 143, outdoor unit heat exchanger 14, interfaces A and B of the first four-way valve 40, and finally flows through gas-liquid separator 13 back to compressor 11. Second heating circuit: Refrigerant flows from D1 interface to A1 and B1 interface, refrigerant in high and low pressure pipes flows back to C1 interface, flows to B1 interface, and then flows through gas-liquid separator 13 and finally flows back to compressor 11.

[0053] See Figure 4 and Figure 9 As shown, when multiple indoor units 20 and auxiliary coils 32 are in heating mode, and air conditioning coil 31 is in cooling mode, the three-pipe multi-split system is in main heating mode. The A and B ports of the first four-way valve 40 are connected, and the C and D ports are connected. The A1 port of the second four-way valve 50 is connected to the B1 and D1 ports, and the B1 port is connected to the C1 port. The first switch 91 and the third switch 93 are open, and the second switch 92 and the fourth switch 94 are closed.

[0054] In main heating mode: After passing through compressor 11, the refrigerant outputs high-temperature, high-pressure gas, which then enters the inlet of oil separator 12 and exits through the outlet of oil separator 12, entering exhaust check valve 16. The refrigerant enters the first four-way valve 40 and the second four-way valve 50 from interfaces D and D1, forming two main heating circuits. In the first main heating circuit: the refrigerant flows from interface D to interface C, then flows into the second main filter 71 and the gas-side shut-off valve 70. The refrigerant flows through indoor unit heat exchanger 21, passing through the third switch 93 and auxiliary coil 32, and flows into liquid-side shut-off valve 60 and the first main filter 61. The refrigerant then flows through main expansion valve 142, second filter 143, outdoor unit heat exchanger 14, interfaces A and B of the first four-way valve 40, and finally flows through gas-liquid separator 13 back to compressor 11. The second main heating circuit: the refrigerant flows from the D1 interface to the A1 and B1 interfaces. The refrigerant in the high and low pressure pipes flows back to the C1 and B1 interfaces of the second four-way valve 50 through the electronic expansion valve 33, the air conditioning coil 31, and the first switch 91. Then it flows through the gas-liquid separator 13 and finally flows back to the compressor 11.

[0055] According to the embodiments of this application, the actual temperature and humidity of the return air from the dehumidifier 30 are detected. The actual dew point temperature of the return air can be calculated from the actual temperature and humidity of the return air from the dehumidifier 30. The user's target dew point temperature is calculated from the target temperature and target humidity set by the dehumidifier 30, and the difference between the actual dew point temperature and the target dew point temperature is compared. When the actual dew point temperature is greater than or equal to the target dew point temperature, the dehumidifier 30 needs to be turned on for dehumidification. When the actual dew point temperature is less than the target dew point temperature, there is no dehumidification requirement, and the dehumidifier 30 does not start. When the dehumidifier 30 is turned on for dehumidification, dehumidification is complete when the actual dew point temperature is less than or equal to the target dew point temperature minus 2. At this point, if there is no further dehumidification requirement, the dehumidifier 30 is turned off.

[0056] The target high-pressure and target low-pressure values ​​of the three-pipe multi-split air conditioning system are calculated using the temperature of the air conditioning coil 31, the target dew point temperature set by the dehumidifier 30, and the temperature of the auxiliary coil 32. The frequency of the compressor 11 and the speed of the fan assembly 141 are then controlled based on these target high-pressure and target low-pressure values, ensuring that the actual low-pressure and actual high-pressure values ​​continuously approach the target low-pressure and target high-pressure values.

[0057] In cooling mode or main cooling mode, the actual low pressure value is controlled by adjusting the frequency of compressor 11, and the actual high pressure value is controlled by detecting the outdoor fan speed and controlling the corresponding valve. In heating mode or main heating mode, the actual high pressure value is controlled by adjusting the frequency of compressor 11, and the actual low pressure value is controlled by detecting the outdoor fan speed and controlling the corresponding valve.

[0058] This application achieves effective control of the indoor unit 20 and the dehumidifier 30 by setting a first four-way valve 40 and a second four-way valve 50. Simultaneously, the parallel connection of the indoor unit 20 and the dehumidifier 30 allows the three-pipe multi-split system to flexibly switch between different operating modes, enabling the dehumidifier 30 to dehumidify without cooling, thereby improving the system's cooling and heating efficiency.

[0059] It should be noted that the technical solutions or features described in the above embodiments can be combined or supplemented with each other without conflict. The scope of protection of this application is not limited to the precise structures described in the above embodiments and shown in the accompanying drawings; all modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A three-pipe multi-split air conditioning system, characterized in that, It includes an outdoor unit, an indoor unit, a dehumidifier, and a first four-way valve and a second four-way valve connected in parallel; the indoor unit and the dehumidifier are connected in parallel; the outdoor unit and the indoor unit are connected through the first four-way valve; the outdoor unit and the dehumidifier are connected through the first four-way valve and the second four-way valve.

2. The three-pipe multi-split air conditioning system according to claim 1, characterized in that, The indoor unit and the dehumidifier are respectively connected to a liquid-side shut-off valve and a gas-side shut-off valve at both ends; both the liquid-side shut-off valve and the gas-side shut-off valve are connected to the first four-way valve; a high-low pressure shut-off valve is connected between the dehumidifier and the outdoor unit, and the high-low pressure shut-off valve is connected to the second four-way valve.

3. The three-pipe multi-split air conditioning system according to claim 2, characterized in that, The indoor unit includes an indoor unit heat exchanger and a first electronic expansion valve connected in series. One end of the indoor unit heat exchanger is connected to the gas-side shut-off valve, and one end of the first electronic expansion valve is connected to the liquid-side shut-off valve. The dehumidifier includes an air conditioning coil and an auxiliary coil connected in parallel. Both the air conditioning coil and the auxiliary coil are connected to electronic expansion valves. One end of the electronic expansion valve is connected to the liquid-side shut-off valve. One end of the air conditioning coil is connected to the gas-side shut-off valve. One end of the auxiliary coil is connected to the high and low pressure shut-off valves.

4. The three-pipe multi-split air conditioning system according to claim 3, characterized in that, The three-pipe multi-split air conditioning system also includes a connecting valve, which has four ports connected in sequence by pipes. The four ports are respectively connected to the gas-side shut-off valve, the air conditioning coil, the high and low pressure shut-off valves, and the auxiliary coil. The connecting valve is equipped with four on / off switches, which are located between two adjacent ports.

5. The three-pipe multi-split air conditioning system according to claim 4, characterized in that, The outdoor unit includes a compressor, an oil separator, a gas-liquid separator, and an outdoor unit heat exchanger; the exhaust port of the compressor is connected to the inlet of the oil separator, and the outlet of the oil separator is connected to the first four-way valve; the inlet of the gas-liquid separator is connected to the first four-way valve and the second four-way valve, and the outlet of the gas-liquid separator is connected to the inlet of the compressor; both ends of the outdoor unit heat exchanger are respectively connected to the first four-way valve and the liquid-side shut-off valve.

6. The three-pipe multi-split air conditioning system according to claim 5, characterized in that, The first four-way valve includes an A port, a B port, a C port, and a D port; the second four-way valve includes an A1 port, a B1 port, a C1 port, and a D1 port; the D port and the D1 port are connected to the air outlet of the oil separator; the D port is connected to the D1 port, and the B port is connected to the B1 port.

7. The three-pipe multi-split air conditioning system according to claim 6, characterized in that, The A interface is switched to be connected to the B interface and the D interface; the C interface is switched to be connected to the B interface and the D interface; the A1 interface is connected to the B1 interface and / or the D1 interface; the C1 interface is switched to be connected to the B1 interface and the D1 interface.

8. The three-pipe multi-split air conditioning system according to claim 5, characterized in that, A low-pressure sensor is provided between the air inlet of the compressor and the air outlet of the gas-liquid separator; a one-way valve and a high-pressure sensor are provided at the air outlet of the oil separator; and an exhaust temperature sensor and a high-pressure switch are provided at the air outlet of the compressor.

9. The three-pipe multi-split air conditioning system according to claim 6, characterized in that, The four on / off switches are designated as the first switch, the second switch, the third switch, and the fourth switch; the four interfaces are designated as the E interface, the F interface, the G interface, and the H interface; the first switch is located between the F interface and the G interface; the second switch is located between the E interface and the F interface; the third switch is located between the E interface and the H interface; and the fourth switch is located between the G interface and the H interface.

10. The three-pipe multi-split air conditioning system according to claim 9, characterized in that, When the three-pipe multi-split air conditioning system is in cooling mode, the A port is connected to the D port, the B port is connected to the C port; the A1 port is connected to the B1 port and the D1 port, and the B1 port is connected to the C1 port; the second switch and the third switch are open, and the first switch and the fourth switch are closed.

11. The three-pipe multi-split air conditioning system according to claim 9, characterized in that, When the three-pipe multi-split air conditioning system is in main cooling mode, the A port is connected to the D port, the B port is connected to the C port; the A1 port is connected to the B1 port, and the C1 port is connected to the D1 port; the second switch and the fourth switch are open, and the first switch and the third switch are closed.

12. The three-pipe multi-split air conditioning system according to claim 9, characterized in that, When the three-pipe multi-split air conditioning system is in heating mode, the A port is connected to the B port, and the C port is connected to the D port; the A1 port is connected to the B1 port and the D1 port, and the B1 port is connected to the C1 port; the second switch and the third switch are open, and the first switch and the fourth switch are closed.

13. The three-pipe multi-split air conditioning system according to claim 9, characterized in that, When the three-pipe multi-split air conditioning system is in main heating mode, the A port is connected to the B port, and the C port is connected to the D port; the A1 port is connected to the B1 port and the D1 port, and the B1 port is connected to the C1 port; the first switch and the third switch are open, and the second switch and the fourth switch are closed.

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