Air conditioning system, air conditioning unit and control method

Abstract

The present invention discloses an air-conditioning system, an air-conditioning unit and a control method. The air-conditioning system includes: a compressor, a four-way valve, an outdoor heat exchanger, a throttling assembly and an indoor heat exchange module which are sequentially connected to form a refrigerant circulation loop. The refrigerant circulation loop is provided with a storage area for temporarily storing liquid refrigerant; the storage area is connected between the indoor heat exchange module and the four-way valve, and is switched to the suction side or the exhaust side of the compressor through the four-way valve. When the refrigerant circulation loop operates in a refrigeration cycle or a defrost cycle, the storage area is connected to the suction side of the compressor; when the refrigerant circulation loop is switched to a heating cycle, the storage area is connected to the exhaust side of the compressor. The present invention can transfer the liquid refrigerant generated during the defrosting process to the storage area. When the defrosting is completed and switched to the heating cycle, the high-temperature and high-pressure refrigerant discharged is used to vaporize the stored liquid refrigerant and bring it into the heating cycle, ultimately achieving the effect of rapid heating after defrosting.

Description

Technical Field

[0001] The present invention relates to the technical field of air-conditioning systems, and in particular to an air-conditioning system, an air-conditioning unit and a control method for realizing liquid refrigerant transfer. Background Art

[0002] Currently, when an air conditioning system is operating in heating mode, the outdoor side is the evaporation side. As the refrigerant evaporates and absorbs heat, the outdoor pipe temperature drops, and frost gradually forms on the surface of the outdoor heat exchanger. When the air conditioning system is in defrosting mode, a four-way valve is generally used to switch the refrigerant flow to the refrigeration cycle. High-temperature gaseous refrigerant enters the outdoor heat exchanger, and the frost layer on the surface of the outdoor heat exchanger absorbs heat to achieve defrosting. After defrosting is completed, the four-way valve switches the refrigerant flow to the heating cycle, and the air conditioning system resumes heating mode. At this time, because the refrigerant in the outdoor heat exchanger on the low-pressure side of the heating mode is not transferred in time after defrosting, a large amount of liquid refrigerant accumulates on the low-pressure side of the outdoor heat exchanger, resulting in slow heating effect and poor heat exchange efficiency after defrosting.

[0003] At the same time, the air-conditioning system has the problem of large differences in the refrigerant circulation volume required for cooling mode and heating mode. While the refrigerant circulation volume meets the requirements of the heating mode, the refrigerant circulation volume in the cooling mode is too high, resulting in a large high and low pressure difference in the system, a large load on the compressor, and poor energy-saving effects. Summary of the Invention

[0004] In order to solve the problem that refrigerant accumulates in the outdoor heat exchanger during the defrosting process of the existing air-conditioning system, resulting in slow heating effect after defrosting, the present invention proposes an air-conditioning system, an air-conditioning unit and a control method for realizing liquid refrigerant transfer. The air-conditioning system can transfer the liquid refrigerant generated during the defrosting process to a storage area. When the defrosting is completed and the heating cycle is switched to, the accumulated liquid refrigerant is vaporized by the exhaust high-temperature and high-pressure refrigerant and brought into the heating cycle, thereby finally achieving the effect of rapid heating after defrosting.

[0005] The technical solution adopted by the present invention is to design an air-conditioning system, including: a compressor, a four-way valve, an outdoor heat exchanger, a throttling component and an indoor heat exchange module which are connected in sequence to form a refrigerant circulation loop. The refrigerant circulation loop is provided with a storage area for temporarily storing liquid refrigerant; the storage area is connected between the indoor heat exchange module and the four-way valve, and is switched to the suction side or the exhaust side of the compressor through the four-way valve.

[0006] In some embodiments, the storage area is the inner cavity of the gas-liquid separator, the first end of the gas-liquid separator is connected to the outlet side of the indoor heat exchange module under the refrigeration cycle, and the second end of the gas-liquid separator is connected to the four-way valve.

[0007] Furthermore, the refrigerant circulation loop is also provided with a refrigerant transfer branch with controllable on / off state. The inlet end of the refrigerant transfer branch is connected to the outlet side of the outdoor heat exchanger in the refrigeration cycle, and the outlet end of the refrigerant transfer branch is connected to the inner cavity of the gas-liquid separator.

[0008] In some embodiments, the storage area is a low-pressure side pipe in the refrigerant circulation loop, and the low-pressure side pipe includes: a connecting pipe between the indoor heat exchange module and the four-way valve.

[0009] In some embodiments, the connecting pipeline between the four-way valve and the outdoor heat exchanger is provided with a transfer section, the transfer section is connected to a gas-liquid separator, the first end of the gas-liquid separator is connected to one end of the transfer section close to the four-way valve, and the second end of the gas-liquid separator is connected to the other end of the transfer section close to the outdoor heat exchanger; wherein, the first end and the second end of the gas-liquid separator, as well as the on-off state of the transfer section are all controllable.

[0010] Furthermore, an oil return hole is provided at the end connected to the four-way valve between the first and second ends of the gas-liquid separator, or both the first and second ends are provided with oil return holes, and the oil return hole is close to the bottom of the inner cavity of the gas-liquid separator.

[0011] Furthermore, an oil return branch connected to the suction side of the compressor is provided at the bottom of the inner cavity of the gas-liquid separator, and the oil return branch is provided with an oil return valve and an oil return throttling member.

[0012] The present invention also provides an air-conditioning unit, which adopts the above-mentioned air-conditioning system.

[0013] In some embodiments, the air conditioning unit is a multi-split unit, and the indoor heat exchange module includes more than two indoor heat exchangers.

[0014] The present invention also provides a control method for an air conditioning system, which is applicable to an embodiment in which the storage area is the inner cavity of a gas-liquid separator. The control method includes:

[0015] After the refrigerant circulation loop runs a defrost cycle, the refrigerant superheat at the outlet of the gas-liquid separator is obtained;

[0016] Determine whether the refrigerant superheat exceeds the set value;

[0017] If so, the throttling component maintains its opening;

[0018] If not, the throttle assembly reduces the opening.

[0019] Furthermore, the control method further includes: before obtaining the refrigerant superheat at the outlet of the gas-liquid separator, timing the actual defrost time of the defrost cycle of the refrigerant circulation loop, and if the actual defrost time reaches the set time threshold t c , then obtain the refrigerant superheat at the outlet of the gas-liquid separator; wherein, the time threshold t is set c <Set the total defrost time.

[0020] In some embodiments, the throttling assembly includes an outdoor throttling valve and an indoor throttling valve;

[0021] When it is determined that the throttling component maintains its opening, the openings of the outdoor throttle valve and the indoor throttle valve remain unchanged;

[0022] When it is determined that the throttling component reduces the opening, the opening of the outdoor throttle valve remains unchanged, and the opening of the indoor throttle valve is reduced.

[0023] Furthermore, the refrigerant superheat is T 出管温度 -T 低压饱和温度 , T 出管温度 is the actual temperature at the outlet of the gas-liquid separator, T 低压饱和温度 It is the saturation temperature corresponding to the suction side pressure of the compressor.

[0024] Furthermore, the control method further includes:

[0025] During the defrost cycle, determine whether the operating parameters of the refrigerant circulation circuit have reached the set defrost exit conditions;

[0026] If so, the defrost cycle is exited, the compressor is shut down, the four-way valve remains in the on state of the defrost cycle, the throttling component is closed, and the refrigerant transfer branch between the outdoor heat exchanger and the gas-liquid separator is connected until the operating parameters of the refrigerant circulation loop reach the set four-way valve reversing conditions;

[0027] If not, maintain the defrost cycle.

[0028] The present invention provides a control method for an air conditioning system. The control method is applicable to an embodiment in which the storage area is a low-pressure side pipe in a refrigerant circulation loop. The control method includes:

[0029] After the refrigerant circulation loop runs a defrost cycle, the suction superheat of the compressor is obtained;

[0030] Adjust the opening of the throttling component according to the suction superheat of the compressor;

[0031] If the suction superheat is higher than the target range, the throttling component increases the opening;

[0032] If the suction superheat is within the target range, the throttling component maintains its opening;

[0033] If the suction superheat is lower than the target range, the throttling component reduces the opening.

[0034] Furthermore, the range above the target interval is divided into at least two upper limit intervals, each upper limit interval is set with a corresponding opening adjustment amplitude, and the upper limit interval with a higher value has a larger opening adjustment amplitude; and / or the range below the target interval is divided into at least two lower limit intervals, each upper limit interval is set with a corresponding opening adjustment amplitude, and the lower limit interval with a lower value has a larger opening adjustment amplitude.

[0035] In some embodiments, the throttling assembly includes an outdoor throttling valve and an indoor throttling valve;

[0036] After the refrigerant circulation loop runs the defrost cycle, the outdoor throttle valve opens to the set maximum opening;

[0037] When it is determined that the throttling component maintains its opening, the openings of the outdoor throttle valve and the indoor throttle valve remain unchanged;

[0038] When it is determined that the throttling component has reduced its opening, the opening of the outdoor throttle valve remains unchanged, while the opening of the indoor throttle valve is reduced;

[0039] When it is determined that the throttling component increases its opening, the opening of the outdoor throttle valve remains unchanged, while the opening of the indoor throttle valve increases.

[0040] Furthermore, the control method further includes:

[0041] During the defrost cycle, determining whether the operating parameters of the refrigerant circulation circuit have reached the set defrost exit conditions;

[0042] If so, the defrost cycle is exited, the compressor is shut down, the four-way valve remains in the on state of the defrost cycle, and the throttling component is opened to the set maximum opening until the operating parameters of the refrigerant circulation circuit reach the set four-way valve reversing conditions;

[0043] If not, maintain the defrost cycle.

[0044] The present invention also provides a control method for an air conditioning system, which is applicable to an embodiment in which a gas-liquid separator is connected between the four-way valve and the outdoor heat exchanger. The control method includes:

[0045] After the refrigerant circulation loop runs a refrigeration cycle or a defrost cycle, the transfer section and the first end of the gas-liquid separator are connected, and the second end of the gas-liquid separator is closed;

[0046] The actual liquid storage time of the refrigerant circulation loop running the refrigeration cycle;

[0047] If the actual liquid storage time is longer than the set liquid storage time, only the transfer section is connected, and the first end and the second end of the gas-liquid separator are closed.

[0048] In some embodiments, the liquid storage time is set to the first liquid storage time corresponding to the actual operating frequency of the compressor and / or the second liquid storage time calculated according to the performance parameters of the air conditioning system. The second liquid storage time t 储存时间 The calculation formula is: 储存时间= Storage capacity of the gas-liquid separator ÷ (Compressor displacement × Operating frequency × Cross-sectional area of ​​the gas-liquid separator inlet pipe); where the storage capacity of the gas-liquid separator is the maximum refrigerant volume required for the heating cycle of the refrigerant circulation circuit minus the maximum refrigerant volume required for the refrigeration cycle of the refrigerant circulation circuit, and the Operating frequency is the target liquid storage frequency of the compressor during the initial stage of the refrigeration cycle or defrost cycle of the refrigerant circulation circuit.

[0049] Compared with the prior art, the present invention has the following beneficial effects:

[0050] 1. The liquid refrigerant generated during the defrosting process is transferred to the storage area. When the defrosting is completed and the heating cycle is switched to, the high-temperature and high-pressure refrigerant discharged by the exhaust gas will gasify the liquid refrigerant stored in the storage area and bring it into the heating cycle, ultimately achieving the effect of rapid heating after defrosting;

[0051] 2. Transfer the liquid refrigerant generated by the refrigeration cycle to the storage area to reduce the refrigerant circulation volume of the refrigeration cycle and solve the problem of the difference in refrigerant circulation volume required in cooling mode and heating mode;

[0052] 3. The gas-liquid separator is designed with an oil return hole and / or oil return branch to achieve oil return during the operation of the air-conditioning system and improve the operating reliability of the compressor. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] The present invention is described in detail below with reference to the embodiments and accompanying drawings, in which:

[0054] Figure 1 is a connection diagram of the first embodiment of the present invention;

[0055] Figure 1a Schematic diagram of the flow direction of the first embodiment of the present invention during a refrigeration cycle or a defrost cycle;

[0056] Figure 1b Schematic diagram of the flow direction of the first embodiment of the present invention during the heating cycle;

[0057] Figure 2 is a connection diagram of the second embodiment of the present invention;

[0058] Figure 2a Schematic diagram of the flow direction of the second embodiment of the present invention during a refrigeration cycle or a defrost cycle;

[0059] Figure 2b 2. It is a schematic diagram of the flow direction of the refrigerant when the machine is shut down and the refrigerant is transferred according to the second embodiment of the present invention;

[0060] Figure 2c is a schematic diagram of the flow direction of the second embodiment of the present invention during the heating cycle;

[0061] Figure 3 is a connection diagram of the third embodiment of the present invention;

[0062] Figure 3a Schematic diagram of the flow direction of the third embodiment of the present invention during a refrigeration cycle or a defrost cycle;

[0063] Figure 3b 1. It is a schematic diagram of the flow direction of refrigerant during shutdown and refrigerant transfer in the third embodiment of the present invention;

[0064] Figure 3c is a schematic diagram of the flow direction of the third embodiment of the present invention during the heating cycle;

[0065] Figure 4 is a connection diagram of a fourth embodiment of the present invention;

[0066] Figure 4a Schematic diagram of the flow direction of the fourth embodiment of the present invention during a refrigeration cycle or a defrost cycle;

[0067] Figure 4b is a schematic diagram of the flow direction of the fourth embodiment of the present invention during the heating cycle;

[0068] Figure 5 is a connection diagram of a fifth embodiment of the present invention;

[0069] Figure 5a 1 is a schematic diagram of the flow direction of the fifth embodiment of the present invention during a refrigeration cycle or a defrost cycle;

[0070] Figure 5b 1 is a schematic diagram of the flow direction of the fifth embodiment of the present invention during the heating cycle;

[0071] Figure 6 is a connection diagram of a sixth embodiment of the present invention;

[0072] Figure 6a is a flow diagram of the sixth embodiment of the present invention during a refrigeration cycle or a defrost cycle;

[0073] Figure 6b 1 is a schematic diagram of the flow direction of refrigerant during shutdown and refrigerant transfer in the sixth embodiment of the present invention;

[0074] Figure 6c It is a flow diagram of the sixth embodiment of the present invention during the heating cycle. DETAILED DESCRIPTION

[0075] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0076] like Figure 1As shown, the air-conditioning system proposed in the present invention can solve the problem of liquid refrigerant accumulating in the outdoor heat exchanger after defrosting. When the defrosting is completed and the system is switched to the heating mode, the accumulated liquid refrigerant is vaporized and brought into the heating cycle by the high-temperature and high-pressure refrigerant discharged by the compressor, thereby achieving the effect of rapid heating after defrosting.

[0077] Specifically, the air-conditioning system includes: a compressor 1, a four-way valve 4, an outdoor heat exchanger 5, a throttling component and an indoor heat exchange module which are connected in sequence to form a refrigerant circulation loop. The outdoor heat exchanger is equipped with an outdoor fan 6. The indoor heat exchange module includes at least one indoor heat exchanger. The refrigerant circulation loop is provided with a storage area for temporarily storing liquid refrigerant. The storage area is connected between the indoor heat exchange module and the four-way valve 4. The storage area is switched to the suction side or the exhaust side of the compressor 1 through the four-way valve 4.

[0078] When the refrigerant circulation loop is operating in the refrigeration cycle or the defrost cycle, the storage area is connected to the suction side of the compressor 1, and the refrigerant is sent back to the suction side of the compressor 1 through the storage area. The liquid refrigerant is stored in the storage area to prevent the liquid refrigerant from accumulating in the outdoor heat exchanger; when the refrigerant circulation loop is switched to the heating cycle, the storage area is connected to the exhaust side of the compressor 1, and the high-temperature refrigerant discharged by the compressor 1 passes through the storage area. The liquid refrigerant in the storage area is heated and vaporized by the high-temperature refrigerant and then brought into the refrigeration cycle, thereby achieving the effect of rapid heating after defrosting.

[0079] It should be understood that the refrigerant flow direction of the "defrost cycle" and the "refrigeration cycle" mentioned above is the same, and the refrigerant flow direction in the refrigerant circulation loop is the exhaust port of the compressor 1 → four-way valve 4 → outdoor heat exchanger 5 → throttling component → indoor heat exchange module → air intake of the compressor 1. The refrigerant flow direction in the refrigerant circulation loop of the "heating cycle" mentioned above is the exhaust port of the compressor 1 → four-way valve 4 → indoor heat exchange module → throttling component → outdoor heat exchanger 5 → air intake of the compressor 1. Of course, other components can be designed in the refrigerant circulation loop, but in different circulation states of the refrigerant circulation loop, the order in which the refrigerant flows through the main components such as the compressor 1, four-way valve 4, outdoor heat exchanger 5, throttling component and indoor heat exchange module should follow the corresponding flow direction.

[0080] The storage area is described below with reference to different embodiments.

[0081] like Figure 1As shown, in the first embodiment of the present invention, the storage area is the inner cavity of the gas-liquid separator 10, and the gas-liquid separator 10 has a first end 101 and a second end 102, one of the first end 101 and the second end 102 serves as an inlet and the other serves as an outlet, the C end of the four-way valve 4 is connected to the outdoor heat exchanger 5, the D end is connected to the exhaust side of the compressor 1 through the oil separator 3, the E end is connected to the second end of the gas-liquid separator 10, and the S end is connected to the suction side of the compressor 1, the bottom of the oil separator 3 is connected back to the suction side of the compressor 1 through the capillary tube 2, and the first end of the gas-liquid separator 10 is connected to the outlet side of the indoor heat exchange module under the refrigeration cycle.

[0082] like Figure 1a As shown, when the refrigerant circulation loop runs a defrost cycle or a refrigeration cycle, the refrigerant is discharged from the compressor 1, enters the outdoor heat exchanger 5 through the oil separator 3 and the four-way valve 4 for condensation and heat exchange, enters the indoor heat exchange module through the throttling component for heat exchange, enters the inner cavity from the first end 101 of the gas-liquid separator 10, and then flows out from the second end 102 of the gas-liquid separator 10, returns to the suction side of the compressor 1 through the four-way valve 4, and stores the liquid refrigerant flowing out of the indoor heat exchange module through the gas-liquid separator 10.

[0083] like Figure 1b As shown, when the refrigerant circulation loop runs a heating cycle, the refrigerant is discharged from the compressor 1, enters the gas-liquid separator 10 through the oil separator 3 and the four-way valve 4, enters from the second end 102 of the gas-liquid separator 10, flows out from the first end 101 of the gas-liquid separator 10, enters the indoor heat exchange module, and is sent to the outdoor heat exchanger 5 for evaporation and heat exchange, and returns to the suction side of the compressor 1 through the four-way valve 4. The high-temperature refrigerant discharged by the compressor 1 vaporizes the liquid refrigerant stored in the gas-liquid separator 10, thereby improving the heating efficiency and restoring the refrigerant circulation amount required by the heating mode.

[0084] like Figure 2 As shown, in the second embodiment of the present invention, the connection structure of the second embodiment is the same as that of the first embodiment, except that the refrigerant circulation circuit is further provided with a refrigerant transfer branch with a controllable on / off state. The inlet end of the refrigerant transfer branch is connected to the outlet side of the outdoor heat exchanger 5 in the refrigeration cycle, and the outlet end of the refrigerant transfer branch is connected to the inner cavity of the gas-liquid separator 10. The refrigerant transfer branch is installed with a refrigerant transfer valve 13, and the on / off state of the refrigerant transfer branch is controlled by the refrigerant transfer valve 13.

[0085] like Figures 2a to 2cAs shown, the operating state of the refrigerant circulation circuit of the second embodiment is the same as that of the first embodiment. The difference is that in the shutdown state between the end of the defrost cycle and the entry into the heating cycle of the refrigerant circulation circuit, the refrigerant transfer valve 13 is opened to connect the refrigerant transfer branch, and the pressure difference between the high-pressure side and the low-pressure side of the refrigerant circulation circuit is used to move the liquid refrigerant of the outdoor heat exchanger 5 to the gas-liquid separator 10 through the refrigerant transfer branch, thereby reducing the liquid refrigerant in the outdoor heat exchanger 5 and ensuring the reliability of the four-way valve 4 when switching.

[0086] like Figure 3 As shown, in the third embodiment of the present invention, the storage area is the low-pressure side piping in the refrigerant circulation loop, the C end of the four-way valve 4 is connected to the outdoor heat exchanger 5, the D end is connected to the exhaust side of the compressor through the oil separator 3, the E end is connected to the indoor heat exchange module, and the S end is connected to the suction side of the compressor 1. The bottom of the oil separator 3 is connected back to the suction side of the compressor 1 through the capillary tube 2. The low-pressure side piping includes: a connecting pipe between the E end of the four-way valve 4 and the indoor heat exchange module.

[0087] like Figure 3a As shown, when the refrigerant circulation loop runs a defrost cycle or a refrigeration cycle, the refrigerant is discharged from the compressor, enters the outdoor heat exchanger 5 through the oil separator 3 and the four-way valve 4 for condensation and heat exchange, enters the indoor heat exchange module through the throttling component for heat exchange, flows into the low-pressure side piping, and returns to the suction side of the compressor 1 through the four-way valve 4.

[0088] like Figure 3b As shown, when the refrigerant circulation loop exits the defrost cycle or the refrigeration cycle, the compressor stops, the four-way valve maintains the on state of the defrost cycle or the refrigeration cycle, the opening of the throttling component is opened to the set maximum opening, and the refrigerant is transferred from the outdoor heat exchanger 5 to the low-pressure side piping under the pressure difference between the high-pressure side and the low-pressure side of the air-conditioning system.

[0089] like Figure 3c As shown, when the refrigerant circulation loop runs the heating cycle, the refrigerant is discharged from the compressor 1, enters the low-pressure side piping through the oil separator 3 and the four-way valve 4, flows out of the low-pressure side piping and enters the indoor heat exchange module, and is then sent to the outdoor heat exchanger 5 for evaporation and heat exchange, and returns to the suction side of the compressor 1 through the four-way valve 4. The high-temperature refrigerant discharged by the compressor vaporizes the liquid refrigerant accumulated in the low-pressure side piping, thereby improving the heating efficiency and restoring the refrigerant circulation volume required by the heating mode.

[0090] Since there is a large difference in the refrigerant circulation volume required for the cooling mode and heating mode of the air-conditioning system, the air-conditioning system proposed in the present invention can also solve the problem of excessive refrigerant circulation volume under the refrigeration cycle. During the refrigeration cycle, part of the refrigerant is sent to the gas-liquid separator to achieve the effect of reducing the refrigerant circulation volume of the refrigeration cycle.

[0091] The following describes the adjustment structure of the refrigerant circulation amount with examples.

[0092] like Figure 4 As shown, in the fourth embodiment of the present invention, the C end of the four-way valve 4 is connected to the outdoor heat exchanger, the D end is connected to the exhaust side of the compressor 1 through the oil separator 3, the E end is connected to the indoor heat exchange module, and the S end is connected to the suction side of the compressor 1. The connecting pipeline between the C end of the four-way valve 4 and the outdoor heat exchanger 5 is provided with a transfer section. The bottom of the oil separator 3 is connected back to the suction side of the compressor 1 through the capillary tube 2. The transfer section is connected to the gas-liquid separator 10. The gas-liquid separator 10 has a first end 101 and a second end 102. One of the first end 101 and the second end 102 serves as an inlet and the other serves as an outlet. The first end 101 of the gas-liquid separator 10 is connected to one end of the transfer section close to the four-way valve 4, and the second end 102 of the gas-liquid separator 10 is connected to the other end of the transfer section close to the outdoor heat exchanger 5, that is, the second end 102 of the gas-liquid separator 10 is connected to the inlet side of the outdoor heat exchanger 5 under the refrigeration cycle. The first end 101 of the gas-liquid separator 10 is provided with a first switch valve 14, the second end 102 is provided with a second switch valve 16, and the transition section is provided with a third switch valve 15. The first to third switch valves are used to control the on-off status of the first end 101, the second end 102 and the transition section of the gas-liquid separator 10.

[0093] like Figure 4a As shown, when the refrigerant circulation loop runs a defrost cycle or a refrigeration cycle, the first switch valve 14 and the third switch valve 15 are opened, and the second switch valve 16 is closed. The refrigerant is discharged from the compressor 1, and after passing through the oil separator 3 and the four-way valve 4, a part of it enters the gas-liquid separator 10 through the first end 101 of the gas-liquid separator 10 to naturally condense and store liquid, and the other part enters the outdoor heat exchanger 5 through the transition section for condensation and heat exchange, and enters the indoor heat exchange module through the throttling component for heat exchange, and then returns to the suction side of the compressor 1 through the four-way valve 4. The excess refrigerant in the defrost cycle or the refrigeration cycle is stored through the gas-liquid separator 10 to avoid a large amount of liquid refrigerant from entering the compressor 1, thereby reducing the power consumption of the compressor 1 and improving the system reliability.

[0094] like Figure 4b As shown, when the refrigerant circulation loop runs a heating cycle, the first switch valve 14 and the second switch valve 16 are opened, and the third switch valve 15 is closed. The refrigerant is discharged from the compressor 1, enters the indoor heat exchange module through the oil separator 3 and the four-way valve 4, and is then sent to the outdoor heat exchanger 5 for evaporation and heat exchange, enters the gas-liquid separator through the second end 102 of the gas-liquid separator 10, and then flows out from the first end 101 of the gas-liquid separator 10, and returns to the suction side of the compressor 1 through the four-way valve 4.

[0095] In the above embodiment designed with a gas-liquid separator, in order to better return oil to the system, the gas-liquid separator 10 is provided with an oil return structure. The oil return structure can be designed as an oil return hole and / or an oil return branch. The lubricating oil in the gas-liquid separator 10 is returned to the compressor through the oil return structure to ensure the reliability of the compressor.

[0096] The oil return structure is described below with reference to the embodiments.

[0097] like Figure 1 As shown, in the first embodiment of the present invention, the first end 101 of the gas-liquid separator 10 extends upward from the bottom of the inner cavity, and the second end 102 of the gas-liquid separator 10 extends downward from the top of the inner cavity, bends at the bottom of the inner cavity, and then extends upward. The first end 101 and the second end 102 of the gas-liquid separator 10 are both provided with an oil return hole 103, and the oil return hole 103 is close to the bottom of the inner cavity.

[0098] During a refrigeration cycle or a defrost cycle, the refrigerant is sent out of the gas-liquid separator 10 from the second end 102. As the refrigerant flows through the second end 102, the lubricating oil that enters the pipeline from the oil return hole at the second end 102 is brought back to the compressor 1. During a heating cycle, the refrigerant is sent out of the gas-liquid separator 10 from the first end 101. As the refrigerant flows through the first end 101, the lubricating oil that enters the pipeline from the oil return hole at the first end 101 is brought to the indoor heat exchange module, and then returns to the compressor 1 through the outdoor heat exchanger 5. Since the first end 101 and the second end 102 of the gas-liquid separator 10 are both designed with an oil return hole 103, oil return from the gas-liquid separator 10 can be achieved without changing the current operating mode. The oil return is fast and efficient, which can greatly improve the operating reliability of the compressor 1 and user comfort.

[0099] like Figure 2 As shown, in the second embodiment of the present invention, the first end 101 of the gas-liquid separator 10 extends downward from the top of the inner cavity, and the second end 102 of the gas-liquid separator 10 extends downward from the top of the inner cavity, bends at the bottom of the inner cavity, and then extends upward. The second end 102 of the gas-liquid separator 10 is provided with an oil return hole 103, and the oil return hole 103 is close to the bottom of the inner cavity.

[0100] During the refrigeration cycle or the defrost cycle, the refrigerant is sent out of the gas-liquid separator 10 from the second end 102. As the refrigerant flows through the second end 102, the lubricating oil that enters the pipeline through the oil return hole at the second end 102 is carried back to the compressor 1. Since the oil return hole 103 is only designed at the second end of the gas-liquid separator 10, oil return is only possible during the refrigeration cycle or the defrost cycle. Oil return cannot be achieved during the heating cycle. The air conditioning system must be controlled to enter the oil return mode and the refrigerant circulation loop must be switched to the refrigeration cycle to achieve oil return from the gas-liquid separator 10.

[0101] like Figure 4As shown, in the fourth embodiment of the present invention, the second end 102 of the gas-liquid separator 10 extends downward from the top of the inner cavity, and the first end 101 of the gas-liquid separator 10 extends downward from the top of the inner cavity, bends at the bottom of the inner cavity, and then extends upward. The first end 101 of the gas-liquid separator 10 is provided with an oil return hole 103, and the oil return hole 103 is close to the bottom of the inner cavity.

[0102] During the heating cycle, the refrigerant is sent out of the gas-liquid separator 10 from the first end 101. As the refrigerant flows through the first end 101, the lubricating oil that enters the pipeline through the oil return hole 103 at the first end 101 is carried back to the compressor 1. Because the second end 102 of the gas-liquid separator 10 is closed during the refrigeration cycle or the defrost cycle in the fourth embodiment, the second end 102 of the gas-liquid separator 10 is not designed with the oil return hole 103, and only supports the refrigerant flow in the heating cycle to achieve oil return.

[0103] like Figures 5 to 5b As shown, in the fifth embodiment of the present invention, the fifth embodiment has the same connection structure as the first embodiment, and the operating state of the refrigerant circulation circuit of the fifth embodiment is also the same as that of the first embodiment. The difference is that the bottom of the inner cavity of the gas-liquid separator 10 is further provided with an oil return branch, which is connected to the suction side of the compressor 1. The oil return branch is provided with an oil return valve 11 and an oil return throttle 12. The oil return throttle 12 here generally refers to a capillary tube. When the oil return valve 11 is opened, the lubricating oil in the inner cavity of the gas-liquid separator 10 returns to the compressor 1 through the oil return throttle 12, thereby ensuring the operational reliability of the compressor 1.

[0104] like Figures 6 to 6c As shown, in the sixth embodiment of the present invention, the sixth embodiment has the same connection structure as the second embodiment, and the operating state of the refrigerant circulation circuit of the sixth embodiment is also the same as that of the second embodiment. The difference is that a return oil branch is further provided at the bottom of the inner cavity of the gas-liquid separator. The return oil branch is connected to the suction side of the compressor and is provided with an oil return valve 11 and an oil return throttle 12. The oil return throttle 12 here generally refers to a capillary tube. When the return oil valve 11 is opened, the lubricating oil in the inner cavity of the gas-liquid separator 10 returns to the compressor 1 through the oil return throttle 12, thereby ensuring the operational reliability of the compressor 1.

[0105] In order to achieve precise control in different embodiments, the present invention further proposes a control method for the above-mentioned air-conditioning system. The process of the control method is described in detail below in conjunction with various embodiments.

[0106] like Figure 1 、 5 As shown, for the first embodiment and the fifth embodiment, the process of the control method is as follows.

[0107] After the refrigerant circulation loop runs the defrost cycle, the refrigerant superheat at the outlet end of the gas-liquid separator 10, the second end 102, is obtained to determine whether the refrigerant superheat exceeds the set value. If so, it means that the temperature inside the gas-liquid separator 10 is relatively high, and the refrigerant in the gas-liquid separator 10 is in an evaporating state, which can ensure that the refrigerant liquid height inside the gas-liquid separator during defrosting will not exceed the maximum capacity of the gas-liquid separator, so the throttling component maintains the opening. If not, it means that the temperature inside the gas-liquid separator 10 is relatively low, and the possibility of condensation and liquefaction of the refrigerant in the gas-liquid separator 10 is relatively high, so the throttling component reduces the opening to reduce the liquid storage amount in the gas-liquid separator 10.

[0108] Among them, the calculation method of refrigerant superheat is preferably T 出管温度 -T 低压饱和温度 , T 出管温度 is the actual temperature at the outlet of the gas-liquid separator, T 低压饱和温度 The saturation temperature corresponding to the suction side pressure of the compressor is compared with the actual temperature at the outlet of the gas-liquid separator 10 and the saturation temperature of the low-pressure side of the system, which can accurately reflect the refrigerant state in the gas-liquid separator.

[0109] In order to improve the accuracy of the throttling component opening adjustment, the control method further includes: after the refrigerant circulation loop runs the defrost cycle, timing the actual defrost time of the refrigerant circulation loop running the defrost cycle, if the actual defrost time reaches the set time threshold t c , then the refrigerant superheat degree at the outlet end of the gas-liquid separator 10, the second end 102, is obtained. c <Set the total defrost time. In other words, the control method is to run the refrigerant circulation loop for a period of time - set the time threshold t c When the refrigerant superheat of the gas-liquid separator 10 is detected, it is predicted whether the liquid stored in the gas-liquid separator 10 will exceed the limit capacity based on the refrigerant superheat, and the throttling component operates according to the judgment result until the defrosting is completed.

[0110] Specifically, the throttling assembly includes an outdoor throttle valve 7 and an indoor throttle valve. The outdoor throttle valve 7 is installed on the outlet side of the outdoor heat exchanger 5 during the refrigeration cycle, and the indoor throttle valve is installed on the inlet side of the indoor heat exchange module during the refrigeration cycle. When the throttling assembly is determined to maintain its opening, the openings of both the outdoor throttle valve 7 and the indoor throttle valve remain unchanged until the defrost is complete. When the throttling assembly is determined to reduce its opening, the opening of the outdoor throttle valve 7 remains unchanged, while the opening of the indoor throttle valve decreases until the defrost is complete. Of course, in actual applications, if only one throttle valve is provided between the outdoor heat exchanger and the indoor heat exchange module, the opening is controlled according to the adjustment method for the indoor throttle valve described above.

[0111] During the above-mentioned defrost cycle, it is determined whether the operating parameters of the refrigerant circulation circuit have reached the set defrost exit conditions; if so, the defrost cycle is exited, the compressor 1 is shut down, and the four-way valve 4 remains in the on state of the defrost cycle until the operating parameters of the refrigerant circulation circuit reach the set four-way valve reversing conditions, and the four-way valve 4 is switched to the on state of the heating cycle; if not, the defrost cycle is maintained.

[0112] It should be noted that the above “set value” and “set time threshold t c " can be obtained through experimental statistics, and the set value can be a constant above 0°C, such as 3°C. The defrost exit condition can be designed to be when the actual defrost time reaches the set total defrost time, that is, when the actual defrost time reaches the set total defrost time, the refrigerant circulation loop exits the defrost cycle. The four-way valve reversing condition can be designed to be when the difference between the exhaust side pressure and the suction side pressure of the compressor drops to the set pressure difference, that is, when the difference between the exhaust side pressure and the suction side pressure of the compressor drops to the set pressure difference, the four-way valve is powered on and switched to the on state of the heating cycle, the compressor is turned on, and the refrigerant circulation loop runs the heating cycle.

[0113] like Figure 2 、 6 As shown, for the second embodiment and the sixth embodiment, the process of the control method is as follows.

[0114] After the refrigerant circulation loop runs the defrost cycle, the refrigerant superheat at the outlet end of the gas-liquid separator 10 - the second end 102 is obtained to determine whether the refrigerant superheat exceeds the set value. If so, it means that the temperature inside the gas-liquid separator 10 is relatively high, and the refrigerant in the gas-liquid separator 10 is in an evaporating state, which can ensure that the refrigerant liquid height inside the gas-liquid separator 10 during the defrost period will not exceed the maximum capacity of the gas-liquid separator 10, so the throttling component maintains the opening. If not, it means that the temperature inside the gas-liquid separator 10 is relatively low, and the possibility of condensation and liquefaction of the refrigerant in the gas-liquid separator 10 is relatively high, so the throttling component reduces the opening to reduce the amount of liquid stored in the gas-liquid separator 10.

[0115] Among them, the calculation method of refrigerant superheat is preferably T 出管温度 -T 低压饱和温度 , T 出管温度 is the actual temperature at the outlet of the gas-liquid separator, T 低压饱和温度 The saturation temperature corresponds to the suction side pressure of the compressor. Comparing the actual temperature at the outlet of the gas-liquid separator with the saturation temperature on the low-pressure side of the system can accurately reflect the refrigerant status in the gas-liquid separator.

[0116] In order to improve the accuracy of the throttling component opening adjustment, the control method further includes: after the refrigerant circulation loop runs the defrost cycle, timing the actual defrost time of the refrigerant circulation loop running the defrost cycle, if the actual defrost time reaches the set time threshold t c, then obtain the refrigerant superheat at the outlet of the gas-liquid separator 10. c <Set the total defrost time. In other words, the control method is to run the refrigerant circulation loop for a period of time - set the time threshold t c When the refrigerant superheat of the gas-liquid separator 10 is detected, it is predicted whether the liquid stored in the gas-liquid separator 10 will exceed the limit capacity based on the refrigerant superheat, and the throttling component operates according to the judgment result until the defrosting is completed.

[0117] Specifically, the throttling assembly includes an outdoor throttle valve 7 and an indoor throttle valve. The outdoor throttle valve 7 is installed on the outlet side of the outdoor heat exchanger 5 during the refrigeration cycle, and the indoor throttle valve is installed on the inlet side of the indoor heat exchange module during the refrigeration cycle. When the throttling assembly is determined to maintain its opening, the openings of both the outdoor throttle valve 7 and the indoor throttle valve remain unchanged until the defrost is complete. When the throttling assembly is determined to reduce its opening, the opening of the outdoor throttle valve 7 remains unchanged, while the opening of the indoor throttle valve decreases until the defrost is complete. Of course, in actual applications, if only one throttle valve is provided between the outdoor heat exchanger and the indoor heat exchange module, the opening is controlled according to the adjustment method for the indoor throttle valve described above.

[0118] During the above-mentioned defrost cycle, it is determined whether the operating parameters of the refrigerant circulation loop have reached the set defrost exit conditions; if so, the defrost cycle is exited, the compressor 1 is shut down, the four-way valve 4 maintains the on-state of the defrost cycle, the throttling component is closed, the refrigerant transfer branch between the outdoor heat exchanger 5 and the gas-liquid separator 10 is connected, and the liquid refrigerant of the outdoor heat exchanger 5 flows to the gas-liquid separator 10 through the refrigerant transfer branch until the operating parameters of the refrigerant circulation loop reach the set four-way valve reversing conditions, the four-way valve 4 is switched to the on-state of the heating cycle, the throttling component is opened, and the refrigerant transfer branch is closed; if not, the defrost cycle is maintained.

[0119] It should be noted that the above “set value” and “set time threshold t c " can be obtained through experimental statistics, and the set value can be a constant above 0°C, such as 3°C. The defrost exit condition can be designed to be when the actual defrost time reaches the set total defrost time, that is, when the actual defrost time reaches the set total defrost time, the refrigerant circulation loop exits the defrost cycle. The four-way valve reversing condition can be designed to be when the difference between the exhaust side pressure and the suction side pressure of the compressor drops to the set pressure difference, that is, when the difference between the exhaust side pressure and the suction side pressure of the compressor drops to the set pressure difference, the four-way valve is powered on and switched to the on state of the heating cycle, the compressor is turned on, and the refrigerant circulation loop runs the heating cycle.

[0120] like Figure 3 As shown, for the third embodiment, the process of the control method is as follows.

[0121] After the refrigerant circulation loop runs the defrost cycle, the suction superheat of compressor 1 is obtained, and the opening of the throttling component is adjusted according to the suction superheat of compressor 1. If the suction superheat is higher than the target range, it means that the suction side temperature of compressor 1 is high and the refrigerant flowing through the indoor heat exchange module is insufficient, so the throttling component increases the opening. If the suction superheat is in the target range, it means that the operating state of compressor 1 is moderate and the throttling component maintains the opening. If the suction superheat is lower than the target range, it means that the suction side temperature of compressor 1 is low, more refrigerant flows through the indoor heat exchange module, and there is a risk of liquid hammer in compressor 1, so the throttling component reduces the opening.

[0122] In order to improve the accuracy of the opening adjustment of the throttling component, the range above the target interval is divided into at least two upper limit intervals, each upper limit interval is set with a corresponding opening adjustment amplitude, and the upper limit interval with a higher value has a larger opening adjustment amplitude; and / or the range below the target interval is divided into at least two lower limit intervals, each upper limit interval is set with a corresponding opening adjustment amplitude, and the lower limit interval with a lower value has a larger opening adjustment amplitude.

[0123] Specifically, the throttling assembly includes an outdoor throttle valve 7 and an indoor throttle valve. The outdoor throttle valve 7 is installed on the outlet side of the outdoor heat exchanger in the refrigeration cycle, and the indoor throttle valve is installed on the inlet side of the indoor heat exchange module in the refrigeration cycle. After the refrigerant circulation loop runs a defrost cycle, the outdoor throttle valve 7 opens to the set maximum opening; when it is determined that the throttle assembly maintains its opening, the openings of the outdoor throttle valve 7 and the indoor throttle valve remain unchanged; when it is determined that the throttle assembly decreases its opening, the opening of the outdoor throttle valve 7 remains unchanged, and the opening of the indoor throttle valve decreases; when it is determined that the throttle assembly increases its opening, the opening of the outdoor throttle valve 7 remains unchanged, and the opening of the indoor throttle valve increases.

[0124] During the above-mentioned defrost cycle, it is determined whether the operating parameters of the refrigerant circulation loop have reached the set defrost exit conditions; if so, the defrost cycle is exited, the compressor 1 is shut down, the four-way valve 4 maintains the on state of the defrost cycle, the throttling component is opened to the set maximum opening, and the pressure difference between the high-pressure side and the low-pressure side of the system is used to allow the refrigerant to continue to transfer from the high-pressure side where the outdoor heat exchanger 5 is located to the low-pressure side piping, until the operating parameters of the refrigerant circulation loop reach the set four-way valve reversing conditions, and the four-way valve 4 is switched to the on state of the heating cycle; if not, the defrost cycle is maintained.

[0125] It should be pointed out that the "target range" and "upper limit range" mentioned above can be obtained through experimental statistics. For example, when the suction superheat is greater than 5°C, the indoor throttle valve is increased by 15 pls per cycle; when the suction superheat is between 2 and 5°C, the indoor throttle valve is increased by 10 pls per cycle; when the suction superheat is equal to 1°C, the indoor throttle valve is maintained at the current opening; when the suction superheat is between -1 and 0°C, the indoor throttle valve is decreased by 10 pls per cycle; when the suction superheat is less than 1°C, the indoor throttle valve is decreased by 20 pls per cycle. The set value can be a constant above 0°C, such as 3°C. The defrost exit condition can be designed to be when the actual defrost time reaches the set total defrost time, that is, when the actual defrost time reaches the set total defrost time, the refrigerant circulation loop exits the defrost cycle. The four-way valve reversing condition can be designed so that the difference between the exhaust side pressure and the suction side pressure of the compressor drops to the set pressure difference, that is, when the difference between the exhaust side pressure and the suction side pressure of the compressor drops to the set pressure difference, the four-way valve is powered on and switched to the on state of the heating cycle, the compressor is turned on, and the refrigerant circulation loop runs the heating cycle.

[0126] like Figure 4 As shown, for the fourth embodiment, the process of the control method is as follows.

[0127] After the refrigerant circulation loop runs a refrigeration cycle or a defrost cycle, the transfer section and the first end 101 of the gas-liquid separator 10 are connected, and the second end 102 of the gas-liquid separator 10 is closed. Part of the refrigerant discharged from the compressor 1 enters the gas-liquid separator 10 for natural condensation. The actual liquid storage time of the refrigerant circulation loop running the refrigeration cycle is timed. If the actual liquid storage time is greater than the set liquid storage time, it means that the refrigerant circulation amount in the refrigerant circulation loop has matched the current mode, and the liquid storage in the gas-liquid separator 10 is completed. Only the transfer section is connected, and the first end 101 and the second end 102 of the gas-liquid separator 10 are closed.

[0128] The liquid storage time is set as the first liquid storage time and / or the second liquid storage time. The correspondence between the actual operating frequency of the compressor and the limit liquid storage time is established in advance through experiments. During the refrigeration cycle or defrost cycle, the actual operating frequency of the compressor is detected and the corresponding limit liquid storage time is obtained from the correspondence. The limit liquid storage time is subtracted from the set margin time to obtain the first liquid storage time. The set margin time can be selected as 30 seconds. The second liquid storage time is calculated based on the performance parameters of the air conditioning system. The second liquid storage time t 储存时间 The calculation formula is: 储存时间= Accumulator storage capacity ÷ (Compressor displacement × Operating frequency × Accumulator inlet pipe cross-sectional area). The compressor displacement and the accumulator inlet pipe cross-sectional area are fixed values. The accumulator storage capacity is the maximum refrigerant volume A required for the refrigerant circulation circuit's heating cycle minus the maximum refrigerant volume B required for the refrigerant circulation circuit's cooling cycle. The operating frequency is the target compressor liquid storage frequency during the refrigerant circulation circuit's cooling cycle or the initial stage of the defrost cycle.

[0129] After the refrigerant circulation loop enters the refrigeration cycle or the defrost cycle, the compressor 1 operates at the target liquid storage frequency, connects the transfer section and the first end 101 of the gas-liquid separator 10, closes the second end 102 of the gas-liquid separator 10, and times the actual liquid storage time of the refrigerant circulation loop running the refrigeration cycle. The actual liquid storage time is compared with the first liquid storage time and the second liquid storage time in real time. When the actual liquid storage time is greater than either the first liquid storage time or the first liquid storage time, the gas-liquid separator ends liquid storage, only connects the transfer section, closes the first end 101 and the second end 102 of the gas-liquid separator 10, and the operating frequency of the compressor 1 is controlled according to the conventional refrigeration cycle or the defrost cycle.

[0130] It should be pointed out that to avoid excessive liquid storage in the gas-liquid separator, a gas-liquid separator that matches the target liquid storage volume should be selected during the air conditioning system selection phase. Furthermore, in actual applications, the target liquid storage frequencies for refrigeration cycles or defrost cycles under different operating conditions can be designed separately. In the early stages of the refrigeration cycle or defrost cycle, the compressor operates at the target liquid storage frequency corresponding to the current operating conditions to store liquid. The first and second liquid storage times are determined based on the target liquid storage frequency. The compressor maintains the target frequency until liquid storage in the gas-liquid separator is complete.

[0131] The air-conditioning system proposed in the present invention is applicable to air-conditioning units, including but not limited to multi-split units. In the multi-split unit, the indoor heat exchange module includes more than two indoor heat exchangers. In order to improve the controllability of the air-conditioning system, the outdoor heat exchanger 5 is connected to the indoor heat exchange module via a liquid side pipe, and the liquid side pipe is equipped with a liquid pipe stop valve 8. The indoor heat exchange module is connected to the four-way valve 4 via a gas side pipe, and the gas side pipe is equipped with a gas pipe stop valve 9. In an embodiment where the storage area is the inner cavity of the gas-liquid separator 10, the first end 101 of the gas-liquid separator 10 is connected to the outlet side of the gas pipe stop valve 9 under the refrigeration cycle, that is, under the refrigeration cycle or the defrost cycle, the refrigerant flowing out of the outdoor heat exchanger 5 first flows through the liquid pipe stop valve 8 and then enters the indoor heat exchange module, and the refrigerant flowing out of the indoor heat exchange module first flows through the gas pipe stop valve 9 and then enters the gas-liquid separator 10.

[0132] It should be noted that the terms used above are intended solely to describe specific embodiments and are not intended to limit the exemplary embodiments of the present invention. When used in this specification, the terms "comprising" and / or "including" indicate the presence of features, steps, operations, devices, components, and / or combinations thereof. Terms such as "first" and "second" are used to define components and facilitate identification. References to "switching valves" and "oil return valves" can employ solenoid valves, and "throttle valves" can employ electronic expansion valves.

[0133] Techniques, methods, and apparatus known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, such techniques, methods, and apparatus should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not limiting. Therefore, other examples of the exemplary embodiments may have different values. It should be noted that similar reference numerals and letters represent similar items in the following figures, and therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0134] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. Air conditioning system, including: A compressor, a four-way valve, an outdoor heat exchanger, a throttling component and an indoor heat exchange module are connected in sequence to form a refrigerant circulation loop; it is characterized in that the refrigerant circulation loop is provided with a storage area for temporarily storing liquid refrigerant, the storage area is connected between the indoor heat exchange module and the four-way valve, and is switched to the suction side or the exhaust side of the compressor through the four-way valve; the storage area is the inner cavity of the gas-liquid separator, the first end of the gas-liquid separator is connected to the outlet side of the indoor heat exchange module under the refrigeration cycle, and the second end of the gas-liquid separator is connected to the four-way valve.

2. The air conditioning system according to claim 1, characterized in that The refrigerant circulation loop is also provided with a refrigerant transfer branch with controllable on / off state. The inlet end of the refrigerant transfer branch is connected to the outlet side of the outdoor heat exchanger in the refrigeration cycle, and the outlet end of the refrigerant transfer branch is connected to the inner cavity of the gas-liquid separator.

3. The air conditioning system according to claim 1 or 2, characterized in that: An oil return hole is provided at the end connected to the four-way valve between the first end and the second end of the gas-liquid separator, or both the first end and the second end are provided with oil return holes, and the oil return hole is close to the bottom of the inner cavity of the gas-liquid separator.

4. The air conditioning system according to claim 1 or 2, characterized in that: An oil return branch connected to the suction side of the compressor is provided at the bottom of the inner cavity of the gas-liquid separator. The oil return branch is provided with an oil return valve and an oil return throttling member.

5. Air conditioning unit, characterized in that, The air-conditioning unit adopts the air-conditioning system according to any one of claims 1 to 4.

6. The air conditioning unit according to claim 5, characterized in that: The air-conditioning unit is a multi-split unit, and the indoor heat exchange module includes more than two indoor heat exchangers.

7. A control method for an air-conditioning system, the control method being applied to the air-conditioning system according to any one of claims 1 to 4; characterized in that: The control method includes: After the refrigerant circulation loop runs a defrost cycle, obtaining the refrigerant superheat at the outlet end of the gas-liquid separator; Determining whether the refrigerant superheat exceeds a set value; If so, the throttling component maintains its opening; If not, the throttle assembly reduces the opening.

8. The control method according to claim 7, characterized in that: Also includes: Before obtaining the refrigerant superheat at the outlet of the gas-liquid separator, the actual defrost time of the defrost cycle of the refrigerant circulation loop is measured. If the actual defrost time reaches the set time threshold t c , then obtain the refrigerant superheat at the outlet of the gas-liquid separator; wherein, the time threshold t is set c <Set the total defrost time.

9. The control method according to claim 7, characterized in that: The throttling assembly includes an outdoor throttle valve and an indoor throttle valve; When it is determined that the throttling component maintains its opening, the openings of the outdoor throttle valve and the indoor throttle valve are maintained unchanged; When it is determined that the throttle assembly has reduced its opening, the opening of the outdoor throttle valve is maintained unchanged, and the opening of the indoor throttle valve is reduced.

10. The control method according to claim 7, characterized in that: The refrigerant superheat is T 出管温度 -T 低压饱和温度 , T 出管温度 is the actual temperature at the outlet of the gas-liquid separator, T 低压饱和温度 is the saturation temperature corresponding to the suction side pressure of the compressor.

11. The control method according to claim 7, characterized in that: Also includes: During the defrost cycle, determining whether the operating parameters of the refrigerant circulation circuit have reached the set defrost exit conditions; If so, the defrost cycle is exited, the compressor is stopped, the four-way valve maintains the on state of the defrost cycle, the throttling component is closed, and the refrigerant transfer branch is connected until the operating parameters of the refrigerant circulation loop reach the set four-way valve reversing conditions; If not, maintain the defrost cycle; The inlet end of the refrigerant transfer branch is connected to the outlet side of the outdoor heat exchanger in the refrigeration cycle, and the outlet end of the refrigerant transfer branch is connected to the inner cavity of the gas-liquid separator.

Images