Air conditioner

Abstract

The present application relates to the technical field of air handling, and discloses an air conditioner. The air conditioner comprises: a compressor; an outdoor heat exchanger; an indoor heat exchanger; a four-way valve, an S port of the four-way valve being connected to an air suction side of the compressor; and a gas-liquid separator, connected between the S port and the air suction side of the compressor and used for separating a gaseous refrigerant from a liquid refrigerant. The gas-liquid separator comprises: a tank body; a gas inlet pipe, connected to the tank body and used for conveying a refrigerant from the S port into the tank body; a gas outlet pipe, a gas suction port of the gas outlet pipe being located in the tank body, a gas outlet of the gas outlet pipe extending out of the tank body and being connected to the air suction side of the compressor, and the gas output pipe being used for supplying the gaseous refrigerant to the compressor; and a blocking device, movably connected in the tank body and used for opening or blocking the gas suction port, when the liquid refrigerant in the tank body rises to a warning level, the blocking device transitioning from an open state to a blocking state.

Description

air conditioner

[0001] Cross-references to related applications

[0002] This application claims priority to Chinese patent application No. 2024227972114, filed on November 15, 2024; and Chinese patent application No. 2024119621106, filed on December 27, 2024, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This application relates to the field of air handling technology, and more particularly to an air conditioner. Background Technology

[0004] When air conditioners are used in large venues such as factories and shopping malls, the distance between the indoor and outdoor units is inevitably relatively far. In such cases, long piping is required to connect the indoor and outdoor units. Additionally, refrigerant needs to be added to ensure the normal operation of the air conditioning system. For air conditioners using long piping, due to the larger amount of refrigerant, during heating sleep mode startup and defrost startup, liquid refrigerant can fill the gas-liquid separator. Excessive liquid refrigerant returning to the compressor can cause liquid slugging and compressor damage. Summary of the Invention

[0005] In some embodiments of this application, an air conditioner includes:

[0006] A compressor is used to compress refrigerant;

[0007] An outdoor heat exchanger is used to perform heat exchange between outdoor air and refrigerant;

[0008] An indoor heat exchanger is used to perform heat exchange between indoor air and refrigerant.

[0009] The four-way valve has ports D, C, E and S. Port D is connected to the discharge end of the compressor, port C is connected to the outdoor heat exchanger, port E is connected to the indoor heat exchanger, and port S is connected to the suction side of the compressor.

[0010] A gas-liquid separator is connected between the S port and the suction side of the compressor to separate the gaseous and liquid states of the refrigerant.

[0011] In some embodiments, the gas-liquid separator includes:

[0012] Tank body;

[0013] The intake pipe, which is connected to the tank, is used to deliver refrigerant from port S into the tank.

[0014] The outlet pipe has its intake port located inside the tank and its outlet port extending outside the tank and connected to the suction side of the compressor, used to supply gaseous refrigerant to the compressor.

[0015] A shielding device, connected to the tank body, is used to open or cover the air intake; the shielding device includes:

[0016] A support plate is rotatably connected to the tank body. The support plate has an open state with the air intake port open and a covered state with the air intake port closed.

[0017] The float is connected to the support plate. As the liquid level in the tank rises, the float causes the support plate to rotate from the open state to the covered state.

[0018] In some embodiments, when the support plate is in a covered state, the float is lower than the air intake in the height direction.

[0019] In some embodiments, the support plate includes: a support body portion, the middle portion of which is rotatably connected to an air outlet pipe; a cover portion connected to the upper end of the support body portion; and a float portion connected to the lower part of the support body portion.

[0020] In some embodiments, a fixing frame is connected to the air outlet pipe; the support plate includes a support body portion, the top end of which is connected to the cover portion at an angle, and the bottom end of which is connected to the float; a support connecting portion, which is connected to the middle portion of the support body portion, and the end of the support connecting portion away from the support body portion is hinged to the fixing frame.

[0021] In some embodiments, the cover plate is provided with a plurality of micropores. When the support plate is in the covered state, the micropores are connected to the air intake port so that the refrigerant can enter the air outlet pipe through the micropores.

[0022] In some embodiments, a through hole is provided on the air outlet pipe near the air inlet; when the support plate is in a covered state, the through hole is higher than the float in the height direction.

[0023] In some embodiments, a filter screen is provided in the outlet pipe near the inlet to block liquid refrigerant.

[0024] In some embodiments, a filter is connected to the outlet pipe near the inlet, the filter comprising: a pipe section; and a filter screen connected to the pipe section.

[0025] In some embodiments, the filter screen is cylindrical, with its upper end connected to the inner wall of the air outlet pipe, and the cross-section of the filter screen gradually decreases from top to bottom.

[0026] In some embodiments of this application, an air conditioner includes a compressor for compressing a refrigerant; an outdoor heat exchanger for performing heat exchange between outdoor air and the refrigerant; an indoor heat exchanger for performing heat exchange between indoor air and the refrigerant; a four-way valve having a D port, a C port, an E port, and an S port, wherein the D port is connected to the discharge end of the compressor, the C port is connected to the outdoor heat exchanger, the E port is connected to the indoor heat exchanger, and the S port is connected to the suction side of the compressor; and a gas-liquid separator connected between the S port and the suction side of the compressor for separating the gaseous and liquid states of the refrigerant.

[0027] The gas-liquid separator includes: a tank; an inlet pipe connected to the tank for delivering refrigerant from port S into the tank; an outlet pipe with its suction port located inside the tank and its outlet extending outside the tank and connected to the suction side of the compressor for supplying gaseous refrigerant to the compressor; and a shielding device connected to the tank for opening or covering the suction port.

[0028] The shielding device is movably connected to the tank body and is used to open or cover the air intake. When the liquid refrigerant in the tank rises to the warning position, the shielding device changes from the open state to the covered state.

[0029] According to some embodiments of this application, an air conditioner is provided, comprising:

[0030] Refrigerant circulation loop;

[0031] A pressure detection device is used to detect the pressure data of the compressor in real time;

[0032] A temperature detection device is used to detect the suction temperature of the compressor in real time;

[0033] The controller is configured to operate during the start-up and transition phases of the air conditioner.

[0034] Obtain the suction superheat of the compressor;

[0035] The refrigerant density ρ in the suction pipe is calculated based on the dynamic pressure at the suction port in the pressure data.

[0036] The suction dryness of the compressor is calculated based on the refrigerant density ρ and refrigerant properties in the suction pipe.

[0037] The compressor is judged to have a risk of liquid slugging based on the suction superheat and suction dryness.

[0038] If there is no risk of liquid slugging, the opening of the expansion valve is adjusted according to the preset control logic; if there is a risk of liquid slugging, the level of liquid slugging risk is determined.

[0039] If the liquid hammer risk level is level one, then control the opening of the expansion valve to decrease to the first opening degree;

[0040] If the liquid hammer risk level is level two, then control the opening of the expansion valve to decrease to the second opening degree;

[0041] If the liquid slugging risk level is level three, then control the air conditioner to shut down;

[0042] The return liquid volume of the third level, the return liquid volume of the second level, and the return liquid volume of the first level are different from each other, and the first opening degree is different from the second opening degree.

[0043] In some embodiments, in the refrigerant circulation loop, the refrigerant circulates sequentially through a compressor, a condenser, an expansion valve, and an evaporator, wherein one of the condenser and the evaporator is an outdoor heat exchanger and the other is an indoor heat exchanger.

[0044] In some embodiments, the return volume of the third level is greater than that of the second level, the return volume of the second level is greater than that of the first level, and the opening degree is greater than that of the second level.

[0045] According to some embodiments of this application, the controller is configured as follows:

[0046] If the intake superheat is not less than the first preset value A, or the intake dryness exceeds the second preset value B, then it is determined that the compressor does not have a risk of liquid slugging.

[0047] If the intake superheat is less than a first preset value A and not less than a fourth preset value W, or if the intake dryness is not greater than a second preset value B, then determine whether the intake dryness is not less than a third preset value C. If yes, then determine that the liquid hammer risk level is the first level, and control the opening of the expansion valve to decrease P to the first opening. If no, then determine that the liquid hammer risk level is the second level, and control the opening of the expansion valve to decrease Q to the second opening.

[0048] If the intake superheat is less than the fourth preset value W, determine whether the intake dryness exceeds the preset threshold D. If yes, determine the liquid slugging risk level as the second level and control the opening of the expansion valve to decrease Q to the second opening. If no, determine the liquid slugging risk level as the third level and control the air conditioner to stop. Wherein, the preset threshold D < the third preset value C.

[0049] According to some embodiments of this application, the temperature detection device is further used to detect the exhaust temperature of the compressor in real time, and the controller is configured to:

[0050] During the stable operation phase of the air conditioner, the intake superheat, the change in intake superheat, the exhaust superheat, and the change in exhaust superheat are obtained.

[0051] The presence of liquid slugging risk in the compressor is determined based on the intake superheat and its change or the exhaust superheat and its change.

[0052] If there is no risk of liquid slugging, the opening of the expansion valve is adjusted according to the preset control logic; if there is a risk of liquid slugging, the liquid slugging risk level of the compressor is determined.

[0053] If the liquid hammer risk level is the first level, then control the opening degree of the expansion valve to decrease by P;

[0054] If the liquid hammer risk level is the second level, then control the opening of the expansion valve to decrease by Q, where Q > P;

[0055] If the liquid slugging risk level is the third level, then the air conditioner is shut down.

[0056] According to some embodiments of this application, the controller is configured as follows:

[0057] If the intake superheat is not less than the first preset value A, it is determined that the compressor does not have a risk of liquid slugging, and the opening of the expansion valve is adjusted according to the preset control logic.

[0058] If the intake superheat is greater than the fifth preset value E and less than the first preset value A, then determine whether the change in intake superheat is not less than the fourth preset value W; if yes, then determine that the liquid hammer risk level is the first level, and at this time control the opening of the expansion valve to decrease by P; if no, then determine that the liquid hammer risk level is the second level, and at this time control the opening of the expansion valve to decrease by Q.

[0059] If the intake superheat is greater than the sixth preset value F and not greater than the fifth preset value E, then the liquid hammer risk level is determined to be the second level, and the opening of the expansion valve is controlled to decrease by Q.

[0060] If the intake superheat is not greater than the sixth preset value F, the liquid slugging risk level is determined to be level three, and the air conditioner is controlled to shut down.

[0061] According to some embodiments of this application, the controller is configured as follows:

[0062] If the exhaust superheat is not less than the seventh preset value G, it is determined that the compressor does not have a risk of liquid slugging. At this time, the opening of the expansion valve is adjusted according to the preset control logic.

[0063] If the exhaust superheat is greater than the eighth preset value H and less than the seventh preset value G, then determine whether the change in exhaust superheat is not less than the fourth preset value W; if yes, then determine that the liquid hammer risk level is the first level, and at this time control the opening of the expansion valve to decrease by P; if no, then determine that the liquid hammer risk level is the second level, and at this time control the opening of the expansion valve to decrease by Q.

[0064] If the exhaust superheat is greater than the ninth preset value I and not greater than the eighth preset value H, then the liquid hammer risk level is determined to be the second level, and the opening of the expansion valve is controlled to decrease by Q.

[0065] If the exhaust superheat is not greater than the ninth preset value I, the liquid slugging risk level is determined to be level three, and the air conditioner is controlled to stop.

[0066] According to some embodiments of this application, the controller is configured as follows:

[0067] During the stable operation phase of the air conditioner, the exhaust superheat and intake superheat of the compressor are obtained;

[0068] Based on the exhaust superheat and intake superheat, determine whether the compressor has a risk of liquid slugging;

[0069] If there is no risk of liquid slugging, the opening of the expansion valve is adjusted according to the preset control logic; if there is a risk of liquid slugging, the liquid slugging risk level of the compressor is determined.

[0070] If the liquid hammer risk level is the first level, then control the opening degree of the expansion valve to decrease by P;

[0071] If the liquid hammer risk level is the second level, then control the opening of the expansion valve to decrease by Q, where Q > P;

[0072] If the liquid slugging risk level is the third level, then the air conditioner is shut down.

[0073] According to some embodiments of this application, the controller is configured as follows:

[0074] If the exhaust superheat is not less than the seventh preset value G, it is determined that the compressor does not have a risk of liquid slugging. At this time, the opening of the expansion valve is adjusted according to the preset control logic.

[0075] If the exhaust superheat is greater than the tenth preset value J and less than the seventh preset value G, then determine whether the intake superheat is not less than the first preset value A; if yes, then determine that the liquid hammer risk level is the first level, and at this time control the opening of the expansion valve to decrease by P; if no, then determine that the liquid hammer risk level is the second level, and at this time control the opening of the expansion valve to decrease by Q.

[0076] If the exhaust superheat is not greater than the tenth preset value J, then the change in the intake superheat is obtained and it is determined whether it is not less than the fourth preset value W; if so, then the liquid slugging risk level is determined to be the second level, and at this time, the opening of the expansion valve is controlled to decrease Q; if not, then the liquid slugging risk level is determined to be the third level, and at this time, the air conditioner is controlled to stop.

[0077] According to some embodiments of this application, the refrigerant circulation loop further includes a float-type gas-liquid separator connected in series between the suction port of the compressor and the outlet of the evaporator, the pressure data includes low-pressure, and the controller is configured to:

[0078] When the air conditioner is running stably, the low-pressure change value is obtained within a preset time period;

[0079] The opening degree of the expansion valve is adjusted according to the low-pressure change value.

[0080] According to some embodiments of this application, the controller is configured as follows:

[0081] Determine whether the low-pressure change value is not less than the eleventh preset value K. If yes, perform multiple determinations and if the result is still yes, control the air conditioner to stop. If no, perform the first determination: whether the low-pressure change value is not less than the twelfth preset value L.

[0082] In the first judgment, if yes, then control the opening degree of the expansion valve to decrease by m; if no, then perform the second judgment: whether the low pressure change value is not less than the thirteenth preset value M.

[0083] In the second judgment, if yes, then control the opening degree of the expansion valve to decrease by n, n < m; if no, then perform the third judgment: whether the low pressure change value is not less than the fourteenth preset value N.

[0084] If the third determination is true, then the opening degree of the expansion valve remains unchanged.

[0085] In another aspect, this application also provides an air conditioner comprising:

[0086] The refrigerant circulation loop, in which the refrigerant circulates sequentially through the compressor, condenser, expansion valve, and evaporator, wherein one of the condenser and the evaporator is an outdoor heat exchanger and the other is an indoor heat exchanger;

[0087] A pressure detection device is used to detect the pressure data of the compressor in real time;

[0088] A temperature detection device is used to detect the suction temperature of the compressor in real time;

[0089] The controller is configured to operate during the start-up and transition phases of the air conditioner.

[0090] Obtain the suction superheat of the compressor;

[0091] The refrigerant density ρ in the suction pipe is calculated based on the dynamic pressure of the suction port in the pressure data, and the suction dryness of the compressor is calculated based on the refrigerant density ρ in the suction pipe and the refrigerant physical property parameters.

[0092] The presence and level of liquid slugging risk in the compressor are determined based on the intake superheat and intake dryness.

[0093] If there is no risk of liquid slugging, the opening degree of the expansion valve is adjusted according to the preset control logic;

[0094] If the liquid slugging risk level is level three, then control the air conditioner to shut down;

[0095] If the liquid hammer risk level is level two, then control the opening degree of the expansion valve to decrease by Q;

[0096] If the liquid hammer risk level is level one, then control the opening degree of the expansion valve to decrease by P;

[0097] Where P < Q, the return volume of the third level is greater than the return volume of the second level, and the return volume of the second level is greater than the return volume of the first level. Attached Figure Description

[0098] Figure 1 is a view showing the appearance of an air conditioner according to some embodiments of this application;

[0099] Figure 2 is a diagram illustrating the flow of refrigerant in an air conditioner according to some embodiments of this application;

[0100] Figure 3 is an external view of a gas-liquid separator in an air conditioner according to some embodiments of the present application;

[0101] Figures 4 and 5 are cross-sectional views illustrating a gas-liquid separator in an air conditioner according to some embodiments of the present application;

[0102] Figures 6 and 7 are internal structural diagrams illustrating a gas-liquid separator in an air conditioner according to some embodiments of the present application;

[0103] Figure 8 is a partial view showing the cover device of the gas-liquid separator in an air conditioner according to some embodiments of the present application in an open state;

[0104] Figure 9 is a partial view showing the covering device of the gas-liquid separator in an air conditioner according to some embodiments of the present application in a covered state;

[0105] Figure 10 is a cross-sectional view showing the filter of the gas-liquid separator in an air conditioner according to some embodiments of the present application;

[0106] Figure 11 is a system block diagram of an air conditioner according to some embodiments of this application;

[0107] Figure 12 is a schematic diagram of the refrigerant circulation loop of an air conditioner according to some embodiments of this application;

[0108] Figure 13 is a schematic diagram of the system structure of an air conditioner according to some embodiments of this application;

[0109] Figure 14 illustrates the control logic of the expansion valve during the start-up and transition phases of an air conditioner according to some embodiments of this application.

[0110] Figure 15 is a control flowchart of the expansion valve of an air conditioner during the start-up and transition phases according to some embodiments of this application.

[0111] Figure 16 illustrates the control logic of the expansion valve of an air conditioner during stable operation according to some embodiments of this application.

[0112] Figure 17 is a control flowchart of the expansion valve of an air conditioner during the stable operation phase according to some embodiments of the present application;

[0113] Figure 18 is a control flowchart of the expansion valve of an air conditioner during the stable operation phase according to some embodiments of the present application;

[0114] Figure 19 illustrates the control logic of the expansion valve of an air conditioner during stable operation according to some embodiments of this application.

[0115] Figure 20 is a control flowchart of the expansion valve of an air conditioner during the stable operation phase according to some embodiments of this application;

[0116] Figure 21 is an external view of a gas-liquid separator in an air conditioner according to some embodiments of this application;

[0117] Figures 22 and 23 are cross-sectional views of a gas-liquid separator in an air conditioner according to some embodiments of the present application at different locations;

[0118] Figures 24 and 25 are internal structural diagrams of a gas-liquid separator in an air conditioner according to some embodiments of this application;

[0119] Figure 26 is a partial view of the cover device of a gas-liquid separator according to some embodiments of the present application in an open state;

[0120] Figure 27 is a partial view of the covering device of a gas-liquid separator according to some embodiments of the present application in a covered state;

[0121] Figure 28 illustrates the control logic for regulating the expansion valve by detecting low-pressure according to some embodiments of this application.

[0122] Figure 29 is a flowchart of a low-pressure pressure regulation expansion valve according to some embodiments of this application;

[0123] Figure 30 is a control flowchart of the expansion valve of the air conditioner during the start-up and transition phases in cooling mode according to some embodiments of this application;

[0124] Figure 31 is a control flowchart of the expansion valve of an air conditioner during the start-up and transition phases in heating mode according to some embodiments of this application. In the above figures, 10 is the air conditioner; 100 is the outdoor unit; 14 and 111 are the compressors; 11 and 112 are the outdoor heat exchangers; 15 and 113 are the four-way valves; 114 is the outdoor throttling device; 16 and 115 are the gas-liquid separators; 12 and 116 are the outdoor fans; 171 is the total pressure sensor; 172 is the high pressure sensor; 173 is the low pressure sensor; 181 is the suction temperature sensor; 182 is the exhaust temperature sensor; 200 is the indoor unit; 21 and 211 are the indoor heat exchangers; 212 is the indoor throttling device; 22 and 213 are the indoor fans; 23 is the indoor unit. Expansion valve; 310, Tank body; 311, Cylinder body; 312, Upper end cover; 313, Lower end cover; 314, Base; 320, Inlet pipe; 320a, Inlet; 320b, Outlet; 330, Outlet pipe; 330a, Intake port; 330b, Outlet port; 331, Through hole; 340, Fixing plate; 341, Limiting part; 400, Covering device; 410, Support plate; 411, Support body part; 412, Support connection part; 413, Cover part; 420, Float body; 431, Micropore; 440, Fixing frame; 500, Filter; 510, Filter screen; 520, Pipe part. Detailed Implementation

[0125] To make the embodiments of this application clearer, the exemplary embodiments of this application will be clearly and completely described below with reference to the accompanying drawings of the exemplary embodiments of this application. Obviously, the exemplary embodiments described are only some embodiments of this application, and not all embodiments.

[0126] In the description of this application, it should be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0127] The terms "first" and "second" are used descriptively only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0128] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0129] The following will refer in detail to some embodiments of this application, and examples of some embodiments of this application are shown in the accompanying drawings.

[0130] Referring to Figure 1, an air conditioner according to some embodiments of this application includes:

[0131] The outdoor unit 100 is located in the outdoor space and is used to perform heat exchange between the refrigerant and the outdoor air;

[0132] The indoor unit 200 is located in the indoor space and is used to perform heat exchange between the refrigerant and the indoor air.

[0133] Referring to FIG2, in some embodiments, the air conditioner includes piping connected between the outdoor unit 100 and the indoor unit 200.

[0134] The piping may include liquid piping P1, on which liquid refrigerant flows.

[0135] The piping may include gas piping P2, on which gaseous refrigerant flows.

[0136] In some embodiments, the outdoor unit 100 includes:

[0137] Compressor 111 compresses the refrigerant;

[0138] Outdoor heat exchanger 112 performs heat exchange between outdoor air and refrigerant;

[0139] The four-way valve 113 selectively guides the refrigerant compressed by the compressor 111 to the outdoor heat exchanger 112 or the indoor unit 200, depending on the heating or cooling mode.

[0140] An outdoor throttling device 114 reduces the pressure of the refrigerant guided to the outdoor heat exchanger 112 in heating mode; and a gas-liquid separator 115 prevents unevaporated liquid refrigerant from flowing to the compressor 111; in some embodiments, the discharge end of the compressor 111 is connected to port D of a four-way valve 113, port C of the four-way valve 113 is connected to the outdoor heat exchanger 112, port E of the four-way valve 113 is connected to the indoor heat exchanger 211 of the indoor unit 200, port S of the four-way valve is connected to the inlet of the gas-liquid separator 115, and the outlet of the gas-liquid separator 115 is connected to the return end of the compressor 111; the compressor 111... The compressor motor (not shown) uses its rotational force to compress the low-pressure gaseous refrigerant to a high pressure. In cooling mode, the four-way valve 113 guides the refrigerant compressed in the compressor 111 to the outdoor heat exchanger 112, and in heating mode, it guides the refrigerant compressed in the compressor 111 to the indoor unit 200. In cooling mode, the outdoor heat exchanger 112 acts as a condenser to condense the refrigerant compressed by the compressor 111, thereby liquefying the gaseous refrigerant. In heating mode, it acts as an evaporator to evaporate the refrigerant depressurized by the indoor unit 200, thereby vaporizing the liquid refrigerant.

[0141] An outdoor fan 116 blows outdoor air to an outdoor heat exchanger 112; in some embodiments, an outdoor throttling device 114 reduces the pressure of the refrigerant by throttling it. As the refrigerant passes through a narrow passage, its pressure decreases without heat exchange with the outside. The outdoor throttling device 114 may specifically be an expansion valve or a capillary tube, etc.

[0142] In some embodiments, the switching of the four-way valve 113 is controlled by a solenoid valve (or other actuating device). The solenoid coil is energized by current, causing the valve core of the four-way valve 113 to displace within the valve body, thus completing the mode switching. This method is fast and suitable for the energy-saving and responsive requirements of air conditioning systems. The control circuit of the four-way valve 113 typically includes sensors, a control unit (such as a thermostat), and a solenoid valve, ensuring that the valve core of the four-way valve 113 switches at the appropriate time. To prevent refrigerant leakage, the four-way valve 113 is equipped with seals (such as O-rings or rubber gaskets) that maintain a tight seal as the valve core moves, preventing any liquid or gaseous refrigerant leakage.

[0143] In some embodiments, the indoor unit 200 includes:

[0144] Indoor heat exchanger 211 performs heat exchange between refrigerant and indoor air;

[0145] The indoor throttling device 212 reduces the pressure of the refrigerant supplied to the indoor heat exchanger 211 in the cooling mode; in some embodiments, the indoor heat exchanger 211 functions as an evaporator in the cooling mode to evaporate the low-pressure liquid refrigerant, thereby vaporizing the liquid refrigerant, and as a condenser in the heating mode to condense the high-pressure gaseous refrigerant, thereby liquefying the gaseous refrigerant.

[0146] The indoor fan 213 blows the air that has exchanged heat with the refrigerant through the indoor heat exchanger 211 into the indoor space.

[0147] In some embodiments described below, the flow of refrigerant in the air conditioner in cooling or heating mode will be described.

[0148] When the air conditioner operates in cooling mode, the compressor 111 of the outdoor unit 100 compresses the refrigerant to a high pressure. As the refrigerant is compressed, its pressure and temperature increase. The compressed refrigerant is guided to the outdoor heat exchanger 112 through the four-way valve 113. The refrigerant condenses in the outdoor heat exchanger 112, and heat exchange occurs between the refrigerant and the outdoor air during condensation. Specifically, the refrigerant changes from a gaseous state to a liquid state. After the condensed liquid refrigerant passes through the outdoor throttling device 114, it is supplied to the indoor unit 200 along the liquid piping P1. The refrigerant supplied to the indoor unit 200 is depressurized through the indoor throttling device 212, and its temperature decreases. The depressurized refrigerant evaporates through the indoor heat exchanger 211, and heat exchange occurs between the refrigerant and the indoor air during evaporation. Specifically, the refrigerant changes from a gaseous state. The evaporated gaseous refrigerant is supplied to the outdoor unit 100 via gas piping P2, and also to the gas-liquid separator 115 via a four-way valve 113. In the gas-liquid separator 115, the refrigerant is separated into unevaporated liquid refrigerant and evaporated gaseous refrigerant, and the gaseous refrigerant is then supplied to the compressor 111 again, completing one refrigerant cycle. As described above, in cooling mode, the air conditioner can cool the indoor air using the heat exchange between the refrigerant generated in the indoor heat exchanger 211 and the indoor air.

[0149] When the air conditioner operates in heating mode, the refrigerant is compressed to high pressure by the compressor 111 of the outdoor unit 100, and the temperature of the refrigerant rises with the pressure. After passing through the four-way valve 113, the compressed refrigerant is guided to the indoor unit 200 along the gas pipe P2. The refrigerant is condensed by the indoor heat exchanger 211, and heat exchange occurs between the refrigerant and the indoor air during condensation. Specifically, the refrigerant changes from a gaseous state to a liquid state. After the condensed liquid refrigerant passes through the indoor throttling device 212, the condensed refrigerant is supplied to the outdoor unit 100 again along the liquid pipe P1. The refrigerant supplied to the outdoor unit 100 is depressurized by the outdoor throttling device 114, and the temperature of the refrigerant decreases. The depressurized refrigerant is evaporated by the outdoor heat exchanger 112, and heat exchange occurs between the refrigerant and the outdoor air during evaporation. In some embodiments, the refrigerant changes to a gaseous state. The gaseous refrigerant evaporated by the outdoor heat exchanger 112 is supplied to the gas-liquid separator 115 via the four-way valve 113. In the gas-liquid separator 115, the refrigerant is separated into unevaporated liquid refrigerant and evaporated gaseous refrigerant, and the gaseous refrigerant is supplied to the compressor 111 again, completing one refrigerant cycle. As described above, in heating mode, the air conditioner can use the heat exchange between the refrigerant generated in the indoor heat exchanger 211 and the indoor air to heat the indoor air.

[0150] When air conditioners are installed in large venues, the distance between the indoor and outdoor units may be particularly far. In this case, long piping is required between the indoor and outdoor units, with lengths potentially reaching 50m or 100m. This increased piping length necessitates increasing the refrigerant charge to ensure the air conditioner's normal operation. During low-temperature heating sleep mode startup at -20℃ and after defrosting startup, the liquid refrigerant returns to the gas-liquid separator 115. Due to the increased refrigerant charge, the liquid level in the gas-liquid separator 115 may exceed the suction port and flow into the compressor 111. This liquid compression in the compressor 111 can damage it.

[0151] Therefore, some embodiments of this application have improved the structure of the gas-liquid separator 115 as follows.

[0152] Referring to Figures 3 and 4, and in conjunction with Figure 5, the gas-liquid separator 115 includes a tank 310. The tank 310 is a closed cylinder, constituting the general appearance of the gas-liquid separator 115. In some embodiments, the tank 310 may include a cylindrical body 311. The cylindrical body 311 is a cylinder with open upper and lower ends. The tank 310 may include an upper end cap 312. The upper end cap 312 is connected to the upper end of the cylindrical body 311 and is used to close the upper end of the cylindrical body 311. The tank 310 may include a lower end cap 313. The upper end cap 313 is connected to the bottom end of the cylindrical body 311 and is used to close the bottom end of the cylindrical body 311. The gas-liquid separator 115 may include a base 314. The base 314 is connected to the bottom end of the lower end cap 313 and is used for fixed connection with the housing of the outdoor unit 100.

[0153] In some embodiments, the gas-liquid separator 115 may include an inlet pipe 320 for supplying refrigerant into the tank 310. The inlet pipe 320 extends through the tank 310. In some embodiments, a portion of the inlet pipe 320 is located outside the tank 310, and a portion of the inlet pipe 320 extends into the tank 310. The external port of the inlet pipe 320 is the inlet 320a of the gas-liquid separator 115 for refrigerant to flow in. The port of the inlet pipe 320 extending into the tank 310 is the outlet 320b of the inlet pipe 320 for refrigerant to flow out into the tank 310.

[0154] In some embodiments, the gas-liquid separator 115 may include an outlet pipe 330 for allowing refrigerant to flow out of the tank 310. The outlet pipe 330 extends through the tank 310. Most of the outlet pipe 330 is located inside the tank 310, and one end of the outlet pipe 330 extends outside the tank 310. The port of the outlet pipe 330 located inside the tank 310 is an intake port 330a for allowing gaseous refrigerant to flow into the outlet pipe 330; the port of the outlet pipe 330 exposed outside the tank 310 is an outlet port 330b of the gas-liquid separator 115 for allowing gaseous refrigerant to flow out of the gas-liquid separator 115. In the refrigerant flow path, the output side of the evaporator is connected to the inlet 320a of the gas-liquid separator 115, and the outlet 330b of the gas-liquid separator 115 is connected to the return gas side of the compressor 111, so that the refrigerant passing through the evaporator flows to the inlet pipe 320. After the gas-liquid separator 115 separates the unevaporated liquid refrigerant from the gaseous refrigerant, it continues to supply the gaseous refrigerant to the return gas side of the compressor 111.

[0155] In some embodiments, the gas-liquid separator 115 is equipped with a baffle or cyclone separator, which further promotes the gas-liquid separation process, ensuring that the liquid refrigerant settles more effectively to the bottom of the tank, while the gaseous refrigerant flows out rapidly through the outlet. The baffle or cyclone separator can enhance the separation capacity of the gas-liquid separator 115, ensuring stable system operation, especially in cases with long piping lengths and large refrigerant charges. Inside the gas-liquid separator 115, the refrigerant enters the tank 310 through the inlet pipe 320, and the gas-liquid separation process begins depending on the flow rate and flow pattern. The liquid refrigerant, due to its higher density, settles to the bottom of the tank, while the gaseous refrigerant rises to the top.

[0156] According to some embodiments of this application, referring to FIG2, the S port of the four-way valve 113 is connected to the inlet 320a of the gas-liquid separator 115 via the first return pipe P3, and the outlet 330b of the gas-liquid separator 115 is connected to the return side of the compressor 111 via the second return pipe P3. In some embodiments, the inlet pipe 320 is generally L-shaped and includes a first inlet pipe portion. The first inlet portion extends vertically, with its top end being the inlet 320a. The inlet pipe 320 includes a second inlet portion. The second inlet portion extends laterally, with its free end being the outlet 320b. The inlet pipe 320 is located at the upper part of the tank 310, allowing the gas-liquid mixed refrigerant to be fully rotated and separated within the tank 310. The first inlet portion and the second inlet portion are connected by an arc portion. In some embodiments, the outlet pipe 330 is U-shaped, with both ports of the outlet pipe 330 located at the top. The gas-liquid mixture of refrigerant flows into the tank 310 along the inlet pipe 320. The liquid refrigerant is heavier and settles at the bottom of the tank 310, while the gaseous refrigerant flows out of the gas-liquid separator 115 along the outlet pipe 330, thereby achieving gas-liquid separation of the refrigerant.

[0157] In some embodiments, referring to FIG6, the gas-liquid separator 115 includes a covering device 400. The covering device 400 is connected inside the gas-liquid separator 115 and is used to cover the suction port 330a when there is a large amount of liquid refrigerant in the gas-liquid separator 115, thereby obstructing the suction flow and reducing the suction pressure. This reduces the amount of liquid refrigerant returning to the compressor 111 through the discharge pipe 330, and can prevent excessive liquid refrigerant from flowing to the compressor 111 and causing damage to the compressor 111.

[0158] In some embodiments, the covering device 400 is rotatably connected to the gas-liquid separator 115. When there is a large amount of liquid refrigerant, for example, when the liquid level reaches the warning position, the covering device 400 rotates to cover the suction port 330a (as shown in Figure 9); when there is a small amount of liquid refrigerant in the gas-liquid separator 115 and the liquid level is normal, the covering device 400 is in the open state with the suction port 330a open (as shown in Figure 8).

[0159] In some embodiments of this application, the covering device 400 has an open state and a covered state. When the liquid level in the gas-liquid separator 115 is low, the covering device 400 is in the open state with the air intake 330a open, which does not affect the normal function of the gas-liquid separator; when the liquid level in the gas-liquid separator 115 is high, the covering device 400 rotates from the open state to the covered state to reduce liquid return.

[0160] In some embodiments, the covering device 400 is connected inside the gas-liquid separator 115 via a rotating mechanism. This rotating mechanism can be implemented by bearings, gears, or an electric drive. The rotating mechanism can automatically activate when the liquid refrigerant level is too high, ensuring that the covering device 400 can effectively cover the suction port 330a, preventing excessive liquid refrigerant from flowing into the compressor. This rotating mechanism can also be connected to a pressure sensor or a liquid level sensor in the system to automatically adjust the state of the covering device 400 according to the liquid level. The covering device 400 can be designed as a rotatable cover, and its shape can be circular or rectangular, depending on the layout of the internal space of the gas-liquid separator 115. Its main function is to automatically rotate and block the suction port 330a when the liquid level is too high. When the liquid level is too high, the covering device 400 rotates to the state of blocking the suction port (covered state), preventing the liquid refrigerant in the gas-liquid mixture from continuing to flow to the outlet pipe 330, thus preventing liquid refrigerant from flowing into the compressor. When the liquid level is normal, the cover device 400 is in the open position, allowing gaseous refrigerant to flow smoothly into the outlet pipe 330.

[0161] In some embodiments, referring to Figures 7 and 8, the covering device 400 includes a support plate 410. The support plate 410 is rotatably connected to the cylinder 311, or the support plate 410 is rotatably connected to the air outlet pipe 330. In some embodiments, the rotation center line A of the support plate 410 is arranged laterally, so that the support plate 410 can rotate vertically. When the support plate 410 rotates in a first direction, it moves towards the air inlet 330a to cover the air inlet 330a; when the support plate 410 rotates in a second direction, it moves away from the air inlet 330a to open the air inlet 330a. In some embodiments, the covering device 400 includes a float 420. The float 420 may be spherical to facilitate floating on the liquid surface. The float 420 is connected to the support plate 410 and is used to drive the support plate 410 to rotate when the liquid level in the gas-liquid separator 115 is high. When the liquid level in the gas-liquid separator 115 is lower than the position of the float 420, the float 420 is not subject to buoyancy from the liquid, and the support plate 410 and the float 420 are in a fully open state under their own weight. When the liquid level in the gas-liquid separator 115 reaches the position of the float 420 and the liquid level continues to rise, the float 420 rises with the liquid level, causing the support plate 410 to rotate in the first direction; when the liquid level drops, the position of the float 420 drops, causing the support plate 410 to rotate in the second direction opposite to the first direction.

[0162] In some embodiments, when the support plate 410 covers the air intake 330a, the height of the float 420 is lower than that of the air intake 330a. That is, the air intake 330a is covered before the liquid level in the gas-liquid separator 115 reaches it, preventing backflow and improving reliability. Since the suction pressure decreases when the cover 413 covers the air intake 330a, the risk of backflow can be determined by detecting the suction pressure. When the liquid level reaches the highest position of the float 420, and the cover 413 covers the air intake 330a, before the liquid level reaches the height of the air intake 330a, the system can detect the change in suction pressure and determine the risk of backflow in advance.

[0163] In some embodiments, the upper part of the support plate 410 is a cover 413. The cover 413 is used to open or cover the air intake 330a. A float 420 is connected to the lower part of the support plate 410. In the height direction, the float 420 is located below the rotation center line A of the support plate 410, and the cover 413 is located above the rotation center line A of the support plate 410. Thus, during the rotation of the support plate 410, the cover 413 and the float 420 move in opposite directions in the height direction. When the float 420 rises, it can drive the support plate 410 to rotate in a first direction, and the position of the cover 413 decreases; when the float 420 falls, the support plate 410 rotates in a second direction, and the position of the cover 413 increases.

[0164] In some embodiments, the support plate 410 includes a support body portion 411. The support body portion 411 is plate-shaped, with a cover portion 430 connected to its top end and a float 420 connected to its bottom end. The support plate 410 includes a support connecting portion 412. The support connecting portion 412 is connected to the middle portion of the support body portion 411. One end of the support connecting portion 412 away from the support body portion 411 is rotatably connected to the air outlet pipe 330.

[0165] In some embodiments, the support body 411 is plate-shaped, providing sufficient area to support the various functions of the covering device. The top of the support body 411 is connected to the cover 413, while the bottom is connected to the float 420, forming a complete support structure. This design ensures that the support plate 410 does not lose stability when rotating and can smoothly drive the float 420 when the liquid level changes, making the function of the covering device within the gas-liquid separator 115 more stable.

[0166] In some embodiments, the gas-liquid separator 115 may include a fixing frame 440. One end of the fixing frame 440 may be fixedly connected to the outlet pipe 330, and the other end of the fixing frame 440 may be hinged to the support connection portion 412, thereby realizing the rotatable connection of the support plate 410 relative to the outlet pipe 330. The fixing frame 440 may be connected to the outlet pipe 330 by means of screws or welding. The fixing frame 440 and the support connection portion 412 may be hinged in the form of a pivot. In some embodiments, the cover portion 430 and the support plate 410 may be connected at an obtuse angle. When the covering device 400 is in the open state, the support body portion 411 is in a generally vertically extending state, and the cover portion 430 extends obliquely upward from the top end of the support body portion 411. When the covering device 400 is in the covered state, the support body portion 411 is inclined, and the cover portion 430 laterally covers the air intake port 330a. The support plate 410 and the cover portion 430 may be integrally formed. When the support plate 410 is made of metal, the cover 430 can be formed by bending the end of the support body 411.

[0167] In some embodiments, when the cover device 400 is fully open, the float 420 abuts against the outlet pipe 330. Thus, due to the obstruction of the outlet pipe 330, the float 420 can only drive the support plate 410 to rotate in the first direction when it rises. In some embodiments, the cover 430 is provided with a plurality of micropores 431. When the cover 430 covers the intake port 330a, the micropores 431 communicate with the outlet pipe 330. By providing micropores 431 on the cover 430, the drastic pressure change caused by the complete closure of the intake port 330a can be prevented. A portion of the refrigerant can be throttled and vaporized after passing through the micropores 431.

[0168] In some embodiments, referring to Figures 8 and 9, a through hole 331 is provided on the outlet pipe 330 near the suction port 330a. When the liquid level reaches the through hole 331, it can enter the outlet pipe 330 through the through hole 331, which can play a buffering role and slow down the problem of liquid refrigerant level rising and rapid liquid return. In some embodiments, there are two through holes 331 arranged vertically, namely a first through hole and a second through hole. The first through hole is located below the second through hole, and the diameter of the first through hole is smaller than the diameter of the second through hole.

[0169] When there is a large amount of liquid refrigerant, the liquid level first reaches the first through hole at the bottom. The liquid level is still some distance away from the suction port 330a. At this time, there is still some time before the liquid returns quickly, so the diameter of the first through hole can be set to be smaller. When the liquid level reaches the second through hole at the top, the liquid level is closer to the suction port 330a. At this time, the time before the liquid returns quickly is more urgent, so the diameter of the second through hole should be set to be larger, so that more refrigerant can flow in from the second through hole, which can improve the buffering effect.

[0170] In some embodiments, the through-hole 331 can also be integrated with the system's liquid level monitoring device to monitor changes in liquid level in real time. When the liquid level reaches a warning level, the system can detect the change through a sensor and adjust the function of the through-hole or activate additional protective measures, such as automatically adjusting the cover device or activating other backflow protection devices, through the control unit. The design of the through-hole 331 can also incorporate a shock-absorbing structure, especially when the liquid refrigerant is flowing rapidly, the opening and closing operation of the through-hole may cause certain shock waves, affecting the stability of the system. Therefore, shock-absorbing or buffering materials can be added to the structure of the through-hole to further improve the system's anti-interference capability.

[0171] In some embodiments, referring to Figures 5 and 10, a filter screen 510 is provided inside the outlet pipe 330 near the intake port 330a. When liquid passes through the filter screen 510, due to the large droplet size, based on the principle of surface tension, the droplets will form a thin film on the surface of the filter medium, which can prevent the droplets from passing through the filter screen 510. After passing through the filter screen 510, the liquid content in the refrigerant is reduced, the gas is purer, and the efficiency of gas-liquid separation can be improved. In addition, the blocking effect of the filter screen 510 on the liquid can prevent a large amount of liquid from rapidly returning to the compressor 111, which can alleviate the liquid inlet rate and suppress excessive liquid refrigerant returning to the compressor 111 and affecting liquid slugging. In some embodiments, the filter screen 510 is conical. The circumferential sides of the filter screen 510 are connected end to end, and the upper and lower sides of the filter screen 510 are open. The upper end of the filter screen 510 is connected to the inner wall of the outlet pipe 330, so that the filter screen 510 has a shape with a gradually decreasing cross-section from top to bottom. In some embodiments, the filter screen 510 has two layers. This increases the resistance of droplets passing through the filter 510, resulting in better droplet interception. However, more layers of filter 510 are not necessarily better, because greater resistance at the filter 510 will increase the system's intake pressure loss, reduce intake density, and lead to a decrease in low-temperature heating capacity.

[0172] In some embodiments, a hole may be provided on the outlet pipe 330 to reduce the pressure drop in the pipe and alleviate the pressure reduction inside the pipe caused by the filter screen 510. In some embodiments, a filter 500 is connected to the outlet pipe 330 near the intake port 330a. The filter 500 includes a pipe portion 520. The pipe portion 520 is cylindrical and is connected to the main pipe of the outlet pipe 330 for refrigerant flow. The filter screen 510 is connected inside the pipe portion 520. The upper end of the filter screen 510 is connected to the inner wall of the pipe portion 520, so that the filter screen 510 has a shape with a gradually decreasing cross-section from top to bottom.

[0173] In some embodiments, referring to Figures 6 and 7, the gas-liquid separator 115 includes two fixing plates 340. One fixing plate 340 is connected to the upper part of the outlet pipe 330, and the other fixing plate 340 is connected to the lower part of the outlet pipe 330, for connecting the two vertical pipes of the outlet pipe 330 to reduce vibration of the outlet pipe 330. The fixing plate 340 is provided with two spaced-apart limiting portions 341. The two vertical pipes of the outlet pipe 330 are clamped between the two limiting portions 341. In some embodiments, the limiting portions 341 may be limiting protrusions. The limiting part 341 can also be a limiting groove, wherein two limiting grooves are provided on the fixing plate 340 at intervals, and the two vertical tubes of the air outlet pipe 330 can be embedded in these limiting grooves to achieve fixation and limiting; or a limiting ring, wherein two limiting rings are provided on the fixing plate 340 at intervals, and the two vertical tubes of the air outlet pipe 330 pass through these limiting rings, and the limiting rings can be tightly attached to the outer wall of the vertical tubes to play a role in fixation and vibration reduction; or a limiting clamp, wherein two limiting clamps are provided on the fixing plate 340 at intervals, and the limiting clamps can be made of elastic material, and the two vertical tubes of the air outlet pipe 330 are clamped between the limiting clamps, and fixation and vibration reduction are achieved by elastic clamping force.

[0174] As can be seen from the above, the air conditioner according to some embodiments of this application includes a covering device 400 disposed within the gas-liquid separator 115, used to cover the suction port 330a when the liquid level in the gas-liquid separator 115 is high, reducing the flow of liquid refrigerant through the outlet pipe 330 to the compressor 111, and avoiding the problem of excessive liquid refrigerant flowing to the compressor 111 and causing damage to the compressor 111. Furthermore, by providing a rotatably connected support plate 410, the support plate 410 has an open state with the suction port 330a open and a covered state with the suction port 330a covered. By providing a float 420 connected to the support plate 410, when the liquid level in the gas-liquid separator 115 is high, the float 420 is subjected to the buoyancy of the liquid and rises with the liquid level, thereby driving the support plate 410 to rotate towards the covered state. Furthermore, by installing a filter screen 510 inside the outlet pipe 330 near the intake port 330a, the liquid refrigerant forms a thin film on the filter screen 510, preventing liquid from passing through the filter screen 510. This reduces the liquid content in the refrigerant passing through the filter screen 510, improving gas-liquid separation efficiency. Additionally, the filter screen 510 prevents a large amount of liquid from rapidly returning to the compressor, thus mitigating the liquid inlet rate.

[0175] In the aforementioned embodiments, the air conditioner effectively suppressed the problem of excessive liquid refrigerant flowing to the compressor through a gas-liquid separator, ensuring the normal operation of the compressor. However, under certain operating conditions, such as the start-up or transition phase of the air conditioner, liquid slugging may still occur, especially during low-temperature heating startup or after defrosting. To further improve the operation of the air conditioner, the following embodiments propose a control strategy based on liquid slugging risk assessment by combining dynamic detection of the compressor's suction superheat, suction dryness, and refrigerant density in the suction pipe. This strategy can effectively avoid liquid slugging and ensure the efficient operation of the air conditioner under various operating conditions.

[0176] This application provides an air conditioner 10 according to some embodiments, and the air conditioner 10 provided by some embodiments of this application is described below. In some embodiments, the air conditioner shown in FIG1 and the air conditioner shown in FIG11 may have the same structure.

[0177] In some embodiments of this application, referring to FIG11, the air conditioner 10 can be a multi-split air conditioner, which includes at least one indoor unit 200. The indoor unit 200 is typically located indoors and is used for heat exchange with the indoor environment. The indoor unit 200 can be configured as a wall-mounted, floor-standing, ceiling-mounted, ducted, curtain-mounted, or ceiling-mounted unit. The air conditioner 10 may include an outdoor unit 100. The outdoor unit 100 is typically located outdoors and is used to carry indoor heat to the outside. The indoor unit 200 and outdoor unit 100 can be configured as an integrated unit or a split unit. The indoor unit 200 may include an indoor unit housing. The indoor unit housing forms the exterior of the indoor unit 200. A mounting cavity is formed within the indoor unit housing. The mounting cavity is used to accommodate and fix various components in the indoor unit 200. The indoor unit housing may include an air inlet. The air inlet communicates with the mounting cavity and serves as an inlet for external air to flow into the indoor unit housing, allowing indoor air to enter the mounting cavity through the air inlet. The indoor unit housing may include an air outlet. The air outlet is connected to the mounting cavity. The air outlet serves as the outlet for the heat exchange airflow inside the indoor unit casing, allowing the airflow inside the mounting cavity to flow out through the air outlet.

[0178] In some embodiments, the indoor unit 200 may include an indoor heat exchanger 21. The indoor heat exchanger 21 is disposed within the mounting cavity and is used for heat exchange with airflow within the indoor unit casing. The indoor unit 200 may include an indoor fan 22. The indoor fan 22 is disposed within the mounting cavity and is used to drive air within the mounting cavity to flow from the air inlet to the air outlet. The outdoor unit 100 may include an outdoor unit casing. The outdoor unit casing has an internal receiving space and forms the appearance of the outdoor unit 100. An outdoor air inlet may be included on the outdoor unit casing. The outdoor air inlet may communicate with the receiving space. The outdoor air inlet may be used to introduce outdoor air into the receiving space. An outdoor air outlet may be included on the outdoor unit casing. The outdoor air outlet may communicate with the receiving space. The outdoor air outlet may be used to exhaust air from the receiving space to the outside of the receiving space. The outdoor unit 100 may include an outdoor heat exchanger 11. The outdoor heat exchanger 11 may be disposed within the receiving space. The outdoor unit 100 may include an outdoor fan 12. The outdoor fan 12 may be disposed within the receiving space. The rotation of the outdoor fan 12 causes outdoor air to enter the housing cavity through the outdoor air inlet and exchange heat with the outdoor heat exchanger 11. The outdoor air after heat exchange flows out of the housing cavity through the outdoor air outlet. In some embodiments, the outdoor heat exchanger 11 is also referred to as an outdoor heat exchanger, the indoor heat exchanger 21 is also referred to as an indoor heat exchanger, the outdoor fan 12 is also referred to as an outdoor fan, and the indoor fan 22 is also referred to as an indoor fan.

[0179] In some embodiments, the air conditioner 10 may include a compressor 14. The compressor 14 is located inside the outdoor unit casing. The compressor 14 is used to compress refrigerant gas in a low-temperature, low-pressure state into refrigerant gas in a high-temperature, high-pressure state, and discharge the compressed refrigerant gas to the condenser 42. The compressor 14 may be an inverter compressor 14. In some embodiments, the outdoor unit 100 may include a gas-liquid separator 16. The gas-liquid separator 16 is used to separate the refrigerant into gas and liquid components. Referring to FIG12, the gas-liquid separator 16 may be located at the suction port of the compressor 14. The gas-liquid separator 16 separates the refrigerant returning from the evaporator to the compressor 14 into gas and liquid, allowing the gas to return to the compressor 14 during operation, reducing the amount of liquid refrigerant entering the compressor 14. This prevents excessive liquid refrigerant from entering the compressor 14, which could alter the state of the lubricating oil inside the compressor 14 or even cause liquid compression, severely reducing the operational reliability of the compressor 14.

[0180] In some embodiments, the outdoor unit 100 may include a four-way valve 15, which selectively guides refrigerant compressed by the compressor 14 to the outdoor heat exchanger or the indoor unit 200 according to the heating or cooling mode. The air conditioner 10 may include a refrigerant circulation loop. Referring to Figure 12, a schematic diagram of the refrigerant circulation loop is shown. Connecting pipes are used to connect the indoor unit 200 and the outdoor unit 100 to form a refrigerant circulation loop. Through the refrigerant circulation loop, the air conditioner 10 allows the refrigerant to circulate in the loop consisting of the compressor 14, the outdoor heat exchanger 11, the indoor heat exchanger 21, the four-way valve 15, and the gas-liquid separator 16, enabling indoor cooling or heating. The evaporator and condenser are respectively the indoor heat exchanger 21 and the outdoor heat exchanger 11. The outdoor unit 100 may include an expansion valve for throttling. The expansion valve may be located in the outdoor unit 100, or simultaneously in both the indoor unit 200 and the outdoor unit 100.

[0181] It is understandable that when the indoor heat exchanger 21 is used as a condenser, the air conditioner 10 is used as a heater in heating mode; when the indoor heat exchanger 21 is used as an evaporator, the air conditioner 10 is used as a cooler in cooling mode. The refrigeration and heating cycles include compression, condensation, expansion, and evaporation processes. Cooling or heating is provided to the indoor space through the refrigerant's heat absorption and release processes, thus regulating the indoor temperature. Specifically, the condenser condenses the high-temperature, high-pressure gaseous refrigerant compressed by the compressor 14 into a liquid refrigerant, and heat is released to the surrounding environment through the condensation process. The liquid refrigerant flowing out of the condenser enters the expansion valve, which expands the high-temperature, high-pressure liquid refrigerant condensed in the condenser into a low-pressure liquid refrigerant. The low-pressure liquid refrigerant flowing from the expansion valve enters the evaporator. As the liquid refrigerant flows through the evaporator, it absorbs heat and evaporates into a low-temperature, low-pressure refrigerant. This low-temperature, low-pressure refrigerant then enters the gas-liquid separator 16 through the four-way valve 15. Gas-liquid separation is performed in the gas-liquid separator 16, allowing the refrigerant gas to return to the compressor 14. The evaporator achieves its cooling effect by utilizing the latent heat of refrigerant evaporation to exchange heat with the material being cooled. Throughout this entire cycle, the air conditioner 10 regulates the temperature of the indoor space.

[0182] In some embodiments, the gas-liquid separator 16 is equipped with a filter or a liquid level detection device to help better separate liquid and gaseous refrigerants. For the separation of liquid refrigerant, the gas-liquid separator can use centrifugal force, gravity, or other methods. The liquid level detection device can monitor the liquid refrigerant level in the gas-liquid separator in real time. This detection device can control the opening and closing of the shielding device to prevent excessive liquid refrigerant from entering the compressor and reduce the risk of liquid slugging.

[0183] In some embodiments, the air conditioner 10 may include a controller 30. The controller 30 is electrically connected to the indoor unit 200 and the outdoor unit 100 to control the operation of their internal components, thereby enabling the various components of the air conditioner 10 to perform their predetermined functions. It is understood that the controller 30 is electrically connected to at least the compressor 14, the expansion valve, the indoor fan 22, and the outdoor fan 12. The controller 30 refers to a device that can generate operation control signals based on instruction operation codes and timing signals, instructing the air conditioner 10 to execute control commands. For example, in response to a received power-on or power-off command from a user, the controller 30 can perform an operation related to the object selected by the power-on or power-off command.

[0184] In some embodiments, the outdoor unit 100 may include a temperature detection device. The temperature detection device is used to detect the suction temperature and discharge temperature of the compressor 14 in real time. Referring to FIG13, the temperature detection device may include a discharge temperature sensor 182, which is installed at the discharge port of the compressor 14 to detect the discharge temperature. The discharge temperature sensor 182 is electrically connected to the controller 30 to transmit the detected discharge temperature to the controller 30 for subsequent control. The temperature detection device may also include a suction temperature sensor 181, which is installed at the suction port of the compressor 14 to detect the suction temperature. The suction temperature sensor 181 is electrically connected to the controller 30 to transmit the detected suction temperature to the controller 30 for subsequent control.

[0185] In related technologies, although setting up a gas-liquid separator 16 can prevent a large amount of liquid refrigerant from entering the compressor 14, liquid return may occur due to improper design or selection of the gas-liquid separator 16, improper control of the opening of the expansion valve (such as when the opening of the expansion valve is too large, the refrigerant in the evaporator may not be completely vaporized, resulting in some liquid refrigerant entering the gas-liquid separator 16), or pressure changes in the air conditioning system.

[0186] In some embodiments, during the start-up, transition, and stable operation phases of the air conditioner, the opening of the expansion valve is adjusted based on different liquid slugging levels to change the state of the refrigerant entering the compressor 14, preventing liquid return and improving the service life of the compressor 14 while ensuring heat exchange efficiency. It is understood that the transition phase refers to the stage after the air conditioner has started operating but has not yet reached a fully stable operating state.

[0187] Referring to Figure 14, controller 30 is configured to operate during the start-up and transition phases of the air conditioner:

[0188] Obtain the suction superheat of compressor 14;

[0189] The refrigerant density ρ inside the suction pipe is calculated based on the dynamic pressure at the suction port in the pressure data.

[0190] The suction dryness of the compressor 14 is calculated based on the refrigerant density ρ in the suction pipe and the refrigerant physical property parameters.

[0191] Based on the intake superheat and intake dryness, it can be determined in advance whether there is a risk of liquid slugging in compressor 14;

[0192] If there is no risk of liquid slugging, the opening of the expansion valve is adjusted according to the preset control logic;

[0193] If the liquid slugging risk level is Level 1, then the opening degree of the control expansion valve is reduced to the first opening degree;

[0194] If the liquid slugging risk level is level two, then the opening degree of the control expansion valve is reduced to the second opening degree;

[0195] If the liquid slugging risk level is level three, then control air conditioner 10 to shut down;

[0196] Among them, the return volume of the third level is greater than that of the second level, the return volume of the second level is greater than that of the first level, and the first opening degree is greater than that of the second opening degree.

[0197] In some embodiments, refrigerant physical properties refer to the physical and chemical properties exhibited by the refrigerant under different operating conditions (such as temperature, pressure, etc.). These parameters are important for the design, commissioning, operation, and maintenance of air conditioning and refrigeration systems because they affect the heat exchange efficiency in the refrigeration cycle, compressor performance, system energy efficiency, etc.

[0198] In some embodiments, the controller 30 continuously acquires information such as suction temperature, discharge temperature, pressure data, and the opening degree of the expansion valve to monitor the system status in real time. During the transition phase, the controller 30 comprehensively judges the level of liquid slugging risk based on changes in suction superheat, suction dryness, and density. If the liquid slugging risk level is low (Level 1), the controller 30 maintains the expansion valve opening unchanged to ensure that the liquid refrigerant is effectively separated in the gas-liquid separator, and that gaseous refrigerant enters the compressor. If the liquid slugging risk level is high, the controller 30 takes measures to reduce the amount of liquid refrigerant entering the compressor. For Level 2 liquid slugging risk, the controller 30 reduces the opening degree of the expansion valve to the second opening degree, thereby reducing the refrigerant flow and preventing incomplete vaporization of the refrigerant in the evaporator. For Level 3, the controller 30 takes more stringent measures, which may include closing the expansion valve or directly shutting down the air conditioner to prevent the compressor from being damaged by liquid slugging. By adjusting the opening of the expansion valve and controlling the start and stop of the air conditioner, the controller 30 can adjust the operating status of the compressor in real time, ensuring that the compressor 14 is not affected by excessive liquid refrigerant during the transition phase, thereby avoiding liquid slugging and protecting the compressor from damage. As the air conditioner gradually stabilizes and the temperature and pressure gradually reach equilibrium, the risk of liquid slugging in the system decreases. At this time, the controller 30 can restore the expansion valve to its normal opening according to the actual operating status of the system.

[0199] In some embodiments, during the start-up and transition phases of the air conditioner, the suction dryness and suction superheat are monitored in real time. Based on these monitoring results, the presence of liquid return and the level of liquid slugging risk are determined in advance, and the opening of the expansion valve is dynamically adjusted. This not only ensures the stable operation of the system but also avoids malfunctions caused by liquid return. Specifically, when the liquid slugging risk level is level three, automatic shutdown is controlled to protect the compressor 14 from damage. When the liquid slugging risk level is not level three, the opening of the expansion valve is reduced in advance to prevent the compressor 14 from drawing in too much liquid refrigerant, thereby avoiding the risk of liquid return.

[0200] Understandably, in some embodiments, the controller 30 can calculate the suction superheat and discharge superheat based on the suction temperature and discharge temperature. In some embodiments, the suction superheat is TsSH, where TsSH = Ts - Te. Here, Ts is the suction temperature of the compressor 14, and Te is the saturation temperature corresponding to the low-pressure Ps, determined by the refrigerant characteristics. The discharge superheat is TdSH, where TdSH = Td - Tc. Here, Td is the discharge temperature of the compressor 14, and Tc is the saturation temperature corresponding to the high-pressure Pd, determined by the refrigerant characteristics.

[0201] In some embodiments, the dynamic pressure at the intake port can be calculated by the difference between the total pressure at the intake port and the static pressure at the intake port. Of course, in other embodiments, other methods for testing the dynamic pressure can also be used to calculate the dynamic pressure at the intake port. In some embodiments, the outdoor unit 100 may include a pressure detection device for detecting the pressure data of the compressor 14. The pressure detection device is electrically connected to the controller 30 to transmit the detected pressure data to the controller 30 for subsequent control. In some embodiments, the pressure detection device may include a high-pressure sensor 172, located at the exhaust port of the compressor 14 to detect high-pressure. The pressure detection device may also include a low-pressure sensor 173, located at the intake port of the compressor 14 to detect low-pressure.

[0202] Understandably, in a refrigeration system, the high-pressure Pd refers to the high-pressure side pressure at the condenser end, which is the pressure state of the refrigerant when it enters the condenser after being compressed by the compressor 14. The low-pressure Ps usually refers to the low-pressure side pressure at the evaporator end, which is the pressure state of the refrigerant inside the evaporator.

[0203] In some embodiments, the pressure detection device may include a total pressure sensor 171, which is disposed at the suction port of the compressor 14 to detect the total pressure at the suction port. The total pressure represents the sum of the static pressure and dynamic pressure of the fluid. It should be noted that the detected low-pressure at the suction port is the static pressure at the suction port. Since the dynamic pressure of the air conditioning system is approximately 10-100 kPa, the total pressure sensor 171 needs to be placed close to the low-pressure sensor 173 to avoid excessive pressure loss in the pipeline due to excessive distance, which could affect the detection accuracy.

[0204] In some embodiments, calculating the refrigerant density ρ in the suction pipe based on the dynamic pressure at the suction port and the curing parameters of the compressor 14 specifically includes:

[0205] Calculate the dynamic pressure (the difference ΔP between the total pressure P1 and the static pressure Ps) based on the total pressure P1 and the static pressure Ps.

[0206] Using the dynamic pressure formula: Calculate the density of the inhalation tube Where V is the flow velocity at the intake port, and V can be calculated based on the curing parameters of compressor 14.

[0207] The curing parameters of compressor 14 may include the frequency H of compressor 14, the displacement L of compressor 14, and the inner diameter D of the suction pipe (inner diameter of the pipe at the pressure acquisition point), according to V = H × L ÷ π ÷ D. 2The flow velocity V can be calculated by multiplying by 4.

[0208] For example, if L = 28 cm³ / r, H = 60 r / s, and the inner diameter of the inhalation tube D = 1.6 cm, then V = 28 × 60 ÷ π ÷ 1.6 2 ×4=835cm / s=8.35m / s. The fixed parameters of compressor 14 are all the parameters determined after the design of air conditioner outdoor unit 100 is completed.

[0209] The calculation of the suction dryness of compressor 14 based on the refrigerant density ρ in the suction pipe and the refrigerant's physical properties specifically includes:

[0210] Based on the refrigerant's physical properties, the saturated liquid density ρ at a given pressure P l saturated gas density ρ g It is certain that the relationship between the refrigerant density ρ in the suction pipe and the actual measured density ρ is: ρ = χρ g +(1-χ)ρ l Based on this relationship, the inhalation dryness can be calculated.

[0211] It is understandable that suction dryness refers to the relative dryness or wetness of the refrigerant at the suction port of compressor 14, and suction dryness characterizes the amount of liquid carried. Dryness represents the mass ratio of gaseous refrigerant (i.e., the proportion of gaseous refrigerant to the total refrigerant mass). The suction dryness χ ranges from 0 to 1, where χ = 0 indicates that the refrigerant is completely liquid, and χ = 1 indicates that the refrigerant is completely gaseous. Under normal circumstances, the suction dryness with superheat is 1. When the dryness is below 1, the amount of liquid carried cannot be determined by pressure and temperature. In actual startup and operation, compressor 14 is strictly prohibited from operating with liquid. It can carry a certain amount of liquid vapor, but the dryness needs to be at a relatively high level, approximately 0.8 to 0.9 or higher.

[0212] Therefore, some embodiments of this application control the intake state of the air conditioner during the start-up process based on the above logic to avoid liquid return from the compressor 14.

[0213] In some embodiments, the presence and level of liquid slugging risk in compressor 14 can be determined in advance based on the suction superheat and suction dryness. Liquid slugging risk may include first level, third level, and high liquid slugging risk.

[0214] In some embodiments, the presence and level of liquid slugging risk in the compressor are determined based on the suction superheat and suction dryness. If no liquid slugging risk exists, the opening of the expansion valve is adjusted according to preset control logic. If the liquid slugging risk level is level three, the air conditioner is shut down; if the liquid slugging risk level is level two, the opening of the expansion valve is reduced by Q; if the liquid slugging risk level is level one, the opening of the expansion valve is reduced by P, where P < Q.

[0215] In some embodiments, the controller 30 is configured to:

[0216] If the superheat of the intake air is not less than the first preset value A, or the dryness of the intake air exceeds the second preset value B, then it is determined that there is no risk of liquid slugging in compressor 14.

[0217] If the intake superheat is less than the first preset value A and not less than the fourth preset value W, or if the intake dryness is less than the second preset value B, determine whether the intake dryness is not less than the third preset value C. If yes, determine the liquid hammer risk level as the first level and control the opening of the expansion valve to decrease by P; if no, determine the liquid hammer risk level as the second level and control the opening of the expansion valve to decrease by Q, where P < Q.

[0218] If the superheat of the intake air is less than the fourth preset value W, determine whether the dryness of the intake air exceeds the preset threshold D. If yes, determine the liquid slugging risk level as the second level and control the opening of the expansion valve to decrease Q. If no, determine the liquid slugging risk level as the third level and control the air conditioner to stop. Wherein, the preset threshold D < the third preset value C.

[0219] In some embodiments, the first preset value A can be 3°C, the second preset value B can be 0.9, the third preset value C can be 0.8, the preset threshold D can be 0.6, and the fourth preset value W can be any value between 0 and 0.3°C.

[0220] In some embodiments, based on real-time data of suction superheat, if the suction superheat is high (e.g., exceeding a preset first value A), it indicates a high proportion of gaseous refrigerant entering the compressor and a low risk of liquid slugging. The controller can allow the expansion valve to maintain a normal opening. If the suction dryness is low (e.g., less than a second preset value B), the controller will determine that there is a risk of liquid slugging and reduce the amount of liquid refrigerant entering the compressor by adjusting the opening of the expansion valve to avoid liquid slugging. The controller 30 can identify system anomalies (such as liquid slugging, abnormal pressure, etc.) based on real-time monitored data and prompt users or technicians for maintenance through fault alarms. When the controller 30 detects a severe risk of liquid slugging (such as a level 3 risk), it can automatically shut down the system to prevent damage to the compressor due to liquid slugging, thereby improving the reliability and service life of the system.

[0221] In some embodiments, referring to Figure 15, the suction superheat and suction dryness are monitored in real time during the air conditioner start-up and transition phases, and step S11 is executed: determining whether the suction superheat TsSH meets the condition TsSH≥3℃, or determining whether the suction dryness χ meets the condition χ>0.9. If so, it is determined that the compressor 14 has no risk of liquid slugging. That is, if TsSH≥3℃ or χ>0.9, the compressor 14 has no risk of liquid slugging. At this time, step S12 is executed: adjusting the opening of the expansion valve according to the preset control logic, that is, adjusting it according to the normal expansion valve. Among them, TsSH≥3℃ indicates that the suction superheat is high, indicating that a lot of refrigerant has evaporated in the evaporator and less unevaporated liquid refrigerant. After further gas-liquid separation by the gas-liquid separator 16, the gaseous refrigerant enters the compressor 14, and the compressor 14 has no risk of liquid slugging. When χ>0.9, it indicates that the suction dryness is high and the liquid refrigerant is less, and the compressor 14 also has no risk of liquid slugging. When there is no risk of liquid slugging, the expansion valve is controlled. The preset control logic is a control logic that compares the intake superheat and exhaust superheat with their relative preset values, and controls the opening of the expansion valve to increase or decrease based on the comparison result. This is an existing conventional technology and will not be described in detail here.

[0222] After completing step S11, if not, i.e. TsSH < 3℃ or χ ≤ 0.9, proceed to step S13: determine whether TsSH satisfies 0℃ ≤ TsSH < 3℃; if yes, proceed to step S14: determine whether the inhalation dryness satisfies χ ≥ 0.8.

[0223] After executing step S14, if the condition is met, the liquid hammer risk level is determined to be level one, and step S15 is executed: control the opening of the expansion valve to decrease P to the first opening; if not, the liquid hammer risk level is determined to be level two, and step S16 is executed: control the opening of the expansion valve to decrease Q to the second opening, where P < Q.

[0224] After completing step S13, if not, proceed to step S17: determine whether the inhalation dryness satisfies χ>0.6.

[0225] After executing step S17, if the condition is met, the liquid slugging risk level is determined to be Level 2, and step S16 is executed: the opening degree of the expansion valve is reduced to the second opening degree. If not, the liquid slugging risk level is determined to be Level 3, and step S18 is executed: the air conditioner is stopped. Wherein, the preset threshold D < the third preset value C.

[0226] In some embodiments, when the suction superheat TsSH is between 0°C and 3°C, if the suction dryness χ ≥ 0.8, it indicates that the liquid carryover in the suction is barely acceptable, and there is a certain amount of suction superheat, belonging to the first level. In this case, the opening of the expansion valve is appropriately reduced by P to reduce the refrigerant flow and lower the risk of liquid return. When the suction superheat TsSH is between 0°C and 3°C, if χ < 0.8, it indicates that there is a lot of liquid carryover in the suction, belonging to the second level. In this case, the opening of the expansion valve needs to be closed more, that is, the opening of the expansion valve needs to be reduced by Q, to increase the suction superheat, prevent excessive liquid carryover in the suction, ensure that the compressor 14 operates in a safe state, improve heat exchange efficiency, avoid energy loss, and improve the overall cooling efficiency of the system. If the suction superheat TsSH is less than 0°C, it usually means that there is a fault or abnormality in the system, so a shutdown operation is performed. In addition, if χ < 0.6, it indicates that there is a lot of liquid return, so the system is directly shut down to protect the compressor 14.

[0227] It should be noted that the opening degree refers to the extent to which the expansion valve opens during operation, usually expressed as a percentage. The percentage of opening degree reflects the proportional relationship between the actual opening of the expansion valve and the maximum possible opening. In this embodiment, P and Q are the actual number of steps in adjusting the expansion valve, which can be defined as the rate of change. Wherein, P = EVO(n-1) / a, Q = EVO(n-1) / b. a and b are fixed parameters.

[0228] It is understandable that the suction superheat of compressor 14 cannot theoretically be less than 0 during normal operation. In some embodiments, a comparison between TsSH and 0°C is added to consider the possibility of malfunctions or abnormalities, further protecting compressor 14. In some embodiments, based on suction superheat and suction dryness, controlling the opening of the expansion valve in advance can effectively prevent liquid return. During the start-up and transition phases of the air conditioner, when in the second stage, the opening of the expansion valve is controlled to be less than that in the first stage, in order to increase the suction superheat in the second stage, prevent excessive liquid carryover in the suction, ensure that compressor 14 operates in a safe state, improve heat exchange efficiency, avoid energy loss, and improve the overall cooling efficiency of the system.

[0229] In some embodiments, referring to FIG16, controller 30 is further configured to:

[0230] During the stable operation phase of the air conditioner, the intake superheat, the change in intake superheat, the exhaust superheat, and the change in exhaust superheat are obtained.

[0231] The risk of liquid slugging in compressor 14 can be determined in advance based on the intake superheat and its change or the exhaust superheat and its change.

[0232] If there is no risk of liquid slugging, the opening of the expansion valve is adjusted according to the preset control logic;

[0233] If there is a risk of liquid slugging, the liquid slugging risk level of compressor 14 is determined in advance. If the liquid slugging risk level is level three, the air conditioner 10 is shut down; otherwise, the opening of the expansion valve is reduced. Specifically, if the liquid slugging risk level is level one, the opening of the expansion valve is reduced by P; if the liquid slugging risk level is level two, the opening of the expansion valve is reduced by Q.

[0234] In some embodiments, the opening of the expansion valve is adjusted according to the suction superheat and the change in suction superheat, or according to the change in discharge superheat and the change in discharge superheat, to change the state of the refrigerant entering the compressor 14, avoid liquid return, and effectively protect the compressor 14 from damage.

[0235] In some embodiments, during the stable operation phase of the air conditioner, in addition to real-time monitoring and adjustment of the expansion valve, the controller 30 also needs to perform periodic system status assessments to ensure that the air conditioner can operate in a better working condition. By periodically calibrating and adjusting the control logic, the controller 30 can continuously improve the opening setting of the expansion valve and the control range of suction superheat and exhaust superheat. Based on long-term system operation data, the controller 30 can optimize the expansion valve control strategy through a self-learning algorithm to cope with the cooling needs under different environments and improve the system's adaptability and efficiency.

[0236] In some embodiments, during the stable operation phase of the air conditioner, the controller 30 is configured to:

[0237] If the intake superheat is not less than the first preset value A, it is determined that there is no risk of liquid slugging in compressor 14, and the opening of the expansion valve is adjusted according to the preset control logic.

[0238] If the intake superheat is greater than the fifth preset value E and less than the first preset value A, then determine whether the change in intake superheat is not less than the fourth preset value W; if yes, then determine the liquid hammer risk level as the first level, and at this time control the opening of the expansion valve to decrease by P; if no, then determine the liquid hammer risk level as the second level, and at this time control the opening of the expansion valve to decrease by Q.

[0239] If the intake superheat is greater than the sixth preset value F but not greater than the fifth preset value E, the liquid hammer risk level is determined to be the second level, and the opening of the expansion valve is reduced by Q.

[0240] If the intake superheat is not greater than the sixth preset value F, the liquid slugging risk level is determined to be level three, and the air conditioner is shut down.

[0241] In some embodiments, when determining the liquid hammer risk level based on the change in intake superheat and intake superheat, and in the second level, the opening of the expansion valve is controlled to be less than the opening of the expansion valve in the first level, so as to quickly increase the intake superheat in the second level, prevent excessive liquid carryover in the intake, and avoid liquid return.

[0242] In some embodiments, the first preset value A can be 3°C, the fifth preset value E can be 1°C, and the sixth preset value F can be 0.5°C.

[0243] In some embodiments, referring to FIG17, the controller 30 is configured to execute step S21: determine whether the suction superheat meets TsSH≥3℃. If so, it is determined that there is no risk of liquid slugging in the compressor 14. At this time, step S22 is executed: adjust the opening of the expansion valve according to the preset control logic, that is, adjust it according to the normal expansion valve.

[0244] After completing step S21, if not, proceed to step S23: determine whether the intake superheat meets the following condition: 1℃ < TsSH < 3℃.

[0245] After completing step S23, if yes, proceed to step S24: determine whether the change in intake superheat satisfies △TsSH≥0℃; if no, proceed to step S25: determine whether the intake superheat satisfies: 0.5℃<TsSH<1℃.

[0246] After executing step S24, if the temperature is ΔTsSH≥0℃, then the liquid hammer risk level is determined to be Level 1, and the next step is executed.

[0247] S26: Control the opening degree of the expansion valve to decrease by P; if not, i.e., △TsSH < 0℃, then determine the liquid hammer risk level as level two, and execute step S27: Control the opening degree of the expansion valve to decrease by Q.

[0248] After executing step S25, if yes, the liquid slugging risk level is determined to be level two. At this time, step S27 is executed again: control the opening of the expansion valve to decrease Q; if no, step S28 is executed: control the air conditioner to stop.

[0249] In some embodiments, when the air conditioner is in a stable operating phase, if the suction superheat TsSH is 3°C or higher, the suction dryness of the compressor 14 is high, and there is no risk of liquid return. The expansion valve is then regulated according to normal valve control. When the suction superheat TsSH is between 1 and 3°C, if ΔTsSH ≥ 0, it indicates an upward trend in suction superheat, meaning that Ts is increasing while Ps remains constant. This indicates an increase in the dryness of the refrigerant absorbed by the air conditioning system, resulting in a low risk of liquid return or accumulation. In this case, the opening of the expansion valve should be appropriately reduced to EVO(n-1) / a. If ΔTsSH < 0, it indicates a downward trend in suction superheat, requiring a larger reduction in the expansion valve opening, i.e., reducing the opening to EVO(n-1) / b to increase suction superheat. When the suction superheat TsSH is between 0.5 and 1°C, the opening of the expansion valve needs to be reduced to EVO(n-1) / b to rapidly increase suction superheat. If TsSH≤0.5℃, it indicates that there is too much liquid return, so the machine should be stopped directly to protect compressor 14.

[0250] In some other embodiments, during the stable operation phase of the air conditioner, the controller 30 is configured to:

[0251] If the exhaust superheat is not less than the seventh preset value G, it is determined that there is no risk of liquid slugging in compressor 14. At this time, the opening of the expansion valve is adjusted according to the preset control logic.

[0252] If the exhaust superheat is greater than the eighth preset value H and less than the seventh preset value G, then determine whether the change in exhaust superheat is not less than the fourth preset value W; if yes, then determine the liquid slugging risk level as the first level, and at this time control the opening of the expansion valve to decrease by P; if no, then determine the liquid slugging risk level as the second level, and at this time control the opening of the expansion valve to decrease by Q.

[0253] If the exhaust superheat is greater than the ninth preset value I but not greater than the eighth preset value H, the liquid hammer risk level is determined to be the second level, and the opening of the expansion valve is reduced by Q.

[0254] If the exhaust superheat is not greater than the ninth preset value I, the liquid slugging risk level is determined to be level three, and the air conditioner is controlled to stop.

[0255] In some embodiments, when determining the liquid slugging risk level based on the change in exhaust superheat and the exhaust superheat, and in the second level, the opening of the expansion valve is controlled to be less than the opening of the expansion valve in the first level, so as to quickly increase the exhaust superheat in the second level, prevent liquid accumulation or liquid return problems, ensure that the compressor 14 operates in a safe state, improve heat exchange efficiency, avoid energy loss, and improve the overall cooling efficiency of the system.

[0256] In some embodiments, the seventh preset value G can be 10°C, the eighth preset value H can be 6°C, and the ninth preset value I can be 4°C.

[0257] In some embodiments, referring to FIG18, step S31 is executed: determine whether the exhaust superheat TdSH meets the requirement of TdSH≥10℃. If so, it is determined that there is no risk of liquid slugging in compressor 14, and step S32 is executed: adjust the opening of the expansion valve according to the preset control logic, that is, adjust it according to the normal expansion valve.

[0258] After completing step S31, proceed to step S33: determine whether the exhaust superheat meets the following condition: 6℃ < TdSH < 10℃.

[0259] After completing step S33, if yes, proceed to step S34: determine whether the change in exhaust superheat satisfies △TdSH≥0℃; if no, proceed to step S35: determine whether the intake superheat satisfies: 4℃<TsSH<6℃.

[0260] After executing step S34, if the condition is met (i.e., △TdSH≥0℃), the liquid hammer risk level is determined to be Level 1, and step S36 is executed: control the opening degree of the expansion valve to decrease by P; if the condition is not met (i.e., △TdSH<0℃), the liquid hammer risk level is determined to be Level 2, and step S37 is executed: control the opening degree of the expansion valve to decrease by Q.

[0261] After executing step S35, if yes, the liquid slugging risk level is determined to be level two. At this time, step S37 is executed again: control the opening of the expansion valve to decrease Q; if no, step S38 is executed: control the air conditioner to stop.

[0262] When the air conditioner is in stable operation, if the discharge superheat TdSH is 10℃ or higher, the dryness of the refrigerant absorbed by compressor 14 (i.e., the suction dryness) is relatively high, and there is no risk of liquid return; normal valve adjustment should be used. If the discharge superheat TdSH is between 6 and 10℃, if...

[0263] If △TdSH≥0, it indicates an increasing trend in exhaust superheat, meaning that with Pd remaining constant, Td is rising. This increases the dryness of the refrigerant absorbed by the air conditioning system, reducing the risk of liquid return or accumulation. The expansion valve opening should be appropriately reduced by P to decrease refrigerant flow, allowing for more complete evaporation and preventing liquid return. If △TdSH<0, it indicates a decreasing trend in exhaust superheat, requiring a larger reduction in the expansion valve opening by decreasing Q to increase suction superheat. When exhaust superheat TdSH is between 4 and 6, the expansion valve opening is reduced by Q to rapidly increase exhaust superheat. If TdSH is less than or equal to 4, it indicates significant liquid return, requiring immediate shutdown to protect compressor 14.

[0264] In some embodiments, the controller 30 can dynamically adjust the control logic based on factors such as ambient temperature, humidity, and system load to adapt to different operating conditions. The controller can automatically adjust the opening of the expansion valve based on changing intake and exhaust superheat, thereby improving system performance. The controller 30 also has fault diagnosis capabilities, enabling it to identify abnormal conditions such as liquid slugging and liquid return, and automatically take protective measures, such as shutting down the system and adjusting the expansion valve opening. By continuously monitoring the system's operating status and combining historical data, the controller 30 improves the expansion valve opening adjustment strategy, further enhancing the system's energy efficiency.

[0265] In some other embodiments, referring to FIG19, during the stable operation phase of the air conditioner, the controller 30 is configured to:

[0266] Obtain the discharge superheat and intake superheat of compressor 14;

[0267] Based on the exhaust superheat and intake superheat, determine in advance whether there is a risk of liquid slugging in compressor 14;

[0268] If there is no risk of liquid slugging, the opening of the expansion valve is adjusted according to the preset control logic;

[0269] If there is a risk of liquid slugging, the liquid slugging risk level of compressor 14 is determined in advance. If the liquid slugging risk level is level three, the air conditioner 10 is shut down; otherwise, the opening of the expansion valve is reduced. Specifically, if the liquid slugging risk level is level one, the opening of the expansion valve is reduced by P; if the liquid slugging risk level is level two, the opening of the expansion valve is reduced by Q.

[0270] In some embodiments, the opening of the expansion valve is adjusted according to the suction superheat and the discharge superheat to change the state of the refrigerant entering the compressor 14, thereby avoiding liquid return and effectively protecting the compressor 14 from damage.

[0271] The controller 30 is configured to:

[0272] If the exhaust superheat is not less than the seventh preset value G, it is determined that there is no risk of liquid slugging in compressor 14. At this time, the opening of the expansion valve is adjusted according to the preset control logic.

[0273] If the exhaust superheat is greater than the tenth preset value J and less than the seventh preset value G, then determine whether the intake superheat is not less than the first preset value A; if yes, then determine the liquid hammer risk level as the first level, and at this time control the opening of the expansion valve to decrease by P; if no, then determine the liquid hammer risk level as the second level, and at this time control the opening of the expansion valve to decrease by Q.

[0274] If the exhaust superheat is not greater than the tenth preset value J, then the change in intake superheat is obtained and it is determined whether it is not less than the fourth preset value W; if so, the liquid slugging risk level is determined to be the second level, and the opening of the expansion valve is reduced by Q; if not, the liquid slugging risk level is determined to be the third level, and the air conditioner is controlled to stop.

[0275] When determining the liquid slugging risk level based on the exhaust superheat and intake superheat, and when the liquid slugging risk level is level two, the opening of the expansion valve is controlled to be less than that of the expansion valve in level one, so as to improve the efficiency of compressor 14 when the liquid slugging risk level is level one, and at the same time, when the liquid slugging risk level is level two, liquid refrigerant is prevented from flowing into compressor 14, thereby reducing liquid return.

[0276] In some embodiments, the tenth preset value J can be 5°C.

[0277] In some embodiments, referring to FIG20, the controller 30 is configured to execute step S41: determine whether the exhaust superheat meets the condition: TdSH≥10℃. If so, it is determined that there is no risk of liquid slugging in the compressor 14, and execute step S42: adjust the opening of the expansion valve according to the preset control logic, that is, adjust it according to the normal expansion valve.

[0278] After completing step S41, if not, proceed to step S43: determine whether the exhaust superheat meets the requirement of 5℃ < TdSH < 10℃.

[0279] After completing step S43, if yes, proceed to step S44: determine whether the intake superheat satisfies TsSH≥3℃. If no, proceed to step S45: determine whether the change in intake superheat satisfies ΔTsSH≥0℃.

[0280] After executing step S44, if the condition is met, the liquid hammer risk level is determined to be Level 1, and step S46 is executed: control the opening degree of the expansion valve to decrease by P; if not, the liquid hammer risk level is determined to be Level 2, and step S47 is executed: control the opening degree of the expansion valve to decrease by Q.

[0281] After completing step S45, if yes, the liquid slugging risk level is determined to be Level 2, and step S46 is executed: control the opening of the expansion valve to decrease Q; if no, step S48 is executed: control the air conditioner to stop.

[0282] In this embodiment, when the air conditioner is in a stable operating phase, if the exhaust superheat TdSH is 10°C or higher, the refrigerant dryness of compressor 14 is high, and there is no risk of liquid return; normal valve regulation applies. When the exhaust superheat TdSH is between 5 and 10°C, if TsSH ≥ 3, it indicates that the suction superheat is not low, the refrigerant dryness of the air conditioning system is not low, the risk of liquid return or accumulation is small, the efficiency of compressor 14 may be slightly lower, and the opening of the expansion valve is only appropriately reduced by P. If TsSH < 3, it indicates that the suction superheat is low, resulting in low exhaust superheat; therefore, the opening of the expansion valve needs to be closed more, i.e., the opening of the expansion valve is reduced by Q to increase the superheat. When the exhaust superheat TdSH < 5, if ΔTsSH ≥ 0, it indicates that the suction superheat has an upward trend; that is, with Ps unchanged, Ts is increasing, the dryness of the refrigerant absorbed by the system is increasing, the risk of liquid return or accumulation is small, and the expansion valve is appropriately reduced by Q. If ΔTsSH < 0, it indicates a decreasing trend in suction superheat and excessive liquid return, so the compressor should be shut down directly to protect compressor 14. It should be noted that the change in suction superheat ΔTsSH = TsSH(n) - TsSH(n-1), where TsSH(n) refers to TsSH at time n, and TsSH(n-1) refers to TsSH at time n-1. The change in exhaust superheat ΔTdSH = TdSH(n) - TdSH(n-1), where TdSH(n) refers to TdSH at time n, and TdSH(n-1) refers to TdSH at time n-1.

[0283] When air conditioners are installed in large venues, the distance between the indoor unit 200 and the outdoor unit 100 may be particularly far. In this case, long connecting pipes are required between the indoor unit 200 and the outdoor unit 100, with lengths potentially reaching 50m or 100m. This increased pipe length necessitates increasing the refrigerant charge to ensure the air conditioner's normal operation. During low-temperature heating sleep mode startup and defrost startup, the liquid refrigerant returns to the gas-liquid separator 16. Due to the increased refrigerant charge, the liquid level in the gas-liquid separator 16 may exceed the suction port and flow into the compressor. This liquid compression in the compressor can damage it.

[0284] Therefore, some embodiments of this application improve the structure of the gas-liquid separator 16, making it a float-type separator. Referring to FIG21, the gas-liquid separator 16 may include: a tank 310. The tank 310 is a closed cylinder, constituting the general appearance of the gas-liquid separator 16. In some embodiments, the tank 310 may include a cylindrical body 311. The cylindrical body 311 is a cylinder with open upper and lower ends. In some embodiments, the tank 310 may include an upper end cap 312. The upper end cap 312 is connected to the upper end of the cylindrical body 311 for closing the upper end of the cylindrical body 311. The tank 310 may include a lower end cap 313. The lower end cap 313 is connected to the bottom end of the cylindrical body 311 for closing the bottom end of the cylindrical body 311. The gas-liquid separator 16 may include a base 314. The base 314 is connected to the bottom end of the lower end cap 313 for fixed connection with the housing of the outdoor unit 100. In some embodiments, the gas-liquid separator 16 may include an inlet pipe 320 for supplying refrigerant into the tank 310. The inlet pipe 320 extends through the tank 310. A portion of the inlet pipe 320 is located outside the tank 310, and a portion of the inlet pipe 320 extends into the tank 310. The external port of the inlet pipe 320 is the inlet 320a of the gas-liquid separator 16 for refrigerant to flow into.

[0285] In some embodiments, referring to FIG22, the port of the inlet pipe 320 extending into the tank 310 is the outlet 320b of the inlet pipe 320, used for refrigerant to flow out into the tank 310. The gas-liquid separator 16 may include an outlet pipe 330 for refrigerant to flow out of the tank 310. The outlet pipe 330 passes through the tank 310. Most of the outlet pipe 330 is located inside the tank 310, and one end of the outlet pipe 330 extends outside the tank 310. The port of the outlet pipe 330 located inside the tank 310 is the refrigerant suction port, used for gaseous refrigerant to flow into the outlet pipe 330; the port of the outlet pipe 330 exposed outside the tank 310 is the outlet 330b of the gas-liquid separator 16, used for gaseous refrigerant to flow out of the gas-liquid separator 16. In some embodiments, the four-way valve 15 is connected to the inlet 320a of the gas-liquid separator 16, and the outlet 330b of the gas-liquid separator 16 is connected to the suction port of the compressor 14.

[0286] In some embodiments, referring to FIG24, the outlet pipe 330 is U-shaped, with both ports located at the top. The gas-liquid mixture of refrigerant flows into the tank 310 along the inlet pipe 320. The liquid refrigerant, being heavier, settles at the bottom of the tank 310, while the gaseous refrigerant flows out of the gas-liquid separator 16 along the outlet pipe 330, thus achieving gas-liquid separation of the refrigerant. In some embodiments, referring to FIG24, the gas-liquid separator 16 may include a covering device 400. The covering device 400 is connected within the gas-liquid separator 16 and is used to cover the refrigerant suction port when there is a large amount of liquid refrigerant in the gas-liquid separator 16. This obstructs the suction flow and reduces the low-pressure area, thereby reducing the amount of liquid refrigerant returning to the compressor via the outlet pipe 330. This prevents excessive liquid refrigerant from flowing to the compressor and causing damage.

[0287] In some embodiments, the covering device 400 is rotatably connected within the gas-liquid separator 16. When there is a large amount of liquid refrigerant, for example, when the liquid level reaches a warning level, the covering device 400 rotates to cover the refrigerant suction port (as shown in Figure 27); when there is a small amount of liquid refrigerant in the gas-liquid separator 16 and the liquid level is normal, the covering device 400 is in the open state, with the refrigerant suction port open (as shown in Figure 28). In some embodiments of this application, the covering device 400 has both an open state and a covered state. When the liquid level in the gas-liquid separator 16 is low, the covering device 400 is in the open state, with the refrigerant suction port open, which does not affect the normal function of the gas-liquid separator 16; when the liquid level in the gas-liquid separator 16 is high, the covering device 400 rotates from the open state to the covered state to reduce liquid return.

[0288] In some embodiments, the covering device 400 includes a support plate 410. The support plate 410 is rotatably connected to the cylinder 311, or the support plate 410 is rotatably connected to the outlet pipe 330. The rotation center line A of the support plate 410 is arranged laterally so that the support plate 410 can rotate vertically. When the support plate 410 rotates in a first direction, it moves toward the refrigerant suction port to cover the refrigerant suction port; when the support plate 410 rotates in a second direction, it moves away from the refrigerant suction port to open the refrigerant suction port.

[0289] In some embodiments, referring to FIG. 25, the covering device 400 includes a float 420. The float 420 may be spherical to facilitate its floating on the liquid surface. The float 420 is connected to a support plate 410 and is used to rotate the support plate 410 when the liquid level in the gas-liquid separator 16 is high. When the liquid level in the gas-liquid separator 16 is lower than the position of the float 420, the float 420 is not subject to buoyancy by the liquid, and the support plate 410 and the float 420 are in a fully open state under their own weight. When the liquid level in the gas-liquid separator 16 reaches the position of the float 420 and the liquid level continues to rise, the float 420 rises with the liquid level, causing the support plate 410 to rotate in a first direction; when the liquid level falls, the position of the float 420 falls, causing the support plate 410 to rotate in a second direction opposite to the first direction.

[0290] In some embodiments, a filter screen is provided inside the outlet pipe 330 near the suction port 330a. When liquid passes through the filter screen, due to the large droplet size, based on the principle of surface tension, the droplets will form a thin film on the surface of the filter medium, which can prevent the droplets from passing through the filter screen. After passing through the filter screen, the liquid content in the refrigerant is reduced, and the gas is purer, which can improve the efficiency of gas-liquid separation. In addition, the blocking effect of the filter screen on the liquid can prevent a large amount of liquid from returning to the compressor quickly, which can slow down the liquid inlet rate and suppress excessive liquid refrigerant returning to the compressor, thus affecting liquid slugging. In some embodiments, referring to FIG23, a filter 500 is connected to the outlet pipe 330 near the suction port 330a.

[0291] In some embodiments, when the support plate 410 covers the refrigerant suction port, the height of the float 420 is lower than the refrigerant suction port. That is, the refrigerant suction port is covered before the liquid level in the gas-liquid separator 16 reaches it, preventing liquid backflow and improving reliability. Since the low-pressure area decreases when the cover 413 covers the refrigerant suction port, the risk of liquid backflow can be determined by detecting the low-pressure area. In some embodiments, the upper part of the support plate 410 is the cover 413. The cover 413 is used to open or cover the refrigerant suction port. The float 420 is connected to the lower part of the support plate 410. In the height direction, the float 420 is located below the rotation center line A of the support plate 410, and the cover 413 is located above the rotation center line A of the support plate 410. Therefore, during the rotation of the support plate 410, the cover 413 and the float 420 move in opposite directions in the height direction. When the float 420 rises, it can drive the support plate 410 to rotate in the first direction, and the cover 430 is lowered; when the float 420 falls, the support plate 410 rotates in the second direction, and the cover 430 is raised.

[0292] In some embodiments, when the cover device 400 is fully open, the float 420 abuts against the outlet pipe 330. Thus, due to the obstruction of the outlet pipe 330, the float 420 can only drive the support plate 410 to rotate in the first direction when it rises. In some embodiments, the cover 430 is provided with a plurality of micropores 431. When the cover 430 covers the intake port 330a, the micropores 431 communicate with the outlet pipe 330. By providing micropores 431 on the cover 430, the drastic pressure change caused by the complete closure of the intake port 330a can be prevented. A portion of the refrigerant can be throttled and vaporized after passing through the micropores 431.

[0293] In some embodiments, referring to Figures 18 and 19, a through hole 331 is provided on the outlet pipe 330 near the suction port 330a. When the liquid level reaches the through hole 331, it can enter the outlet pipe 330 through the through hole 331, which can play a buffering role and slow down the problem of liquid refrigerant level rising and rapid liquid return. When the liquid level reaches the float 420 just as it rises to the highest position of the float 420, the cover 413 covers the refrigerant suction port of 430. At this time, the liquid level has not yet risen to the height of the refrigerant suction port. The system can detect the change in suction pressure (the low pressure detected by the low pressure sensor is the suction pressure), judge in advance that there is a risk of liquid return, and thus control the opening of the expansion valve.

[0294] In some embodiments, when the air conditioner is operating stably, the controller 30 is configured to:

[0295] Obtain the low-pressure change value within a preset time period;

[0296] Adjusting the opening of the expansion valve or controlling the air conditioner to stop based on changes in low-pressure value.

[0297] In some embodiments, the opening of the expansion valve is adjusted according to the change in low pressure, i.e., the change in pressure at the suction port, to change the state of the refrigerant entering the compressor 14, thereby preventing liquid refrigerant from flowing into the compressor 14 and reducing liquid return.

[0298] In some embodiments, the controller 30 is configured to:

[0299] Determine whether the low-pressure change value is not less than the eleventh preset value K. If yes, perform multiple checks and if the low-pressure change value is still not less than the eleventh preset value K, then control the air conditioner to stop. If no, perform the first check: whether the low-pressure change value is not less than the twelfth preset value L.

[0300] In the first judgment, if yes, the opening degree of the expansion valve is reduced by m; if no, the second judgment is made: whether the change value of the low pressure is not less than the thirteenth preset value M.

[0301] In the second judgment, if yes, then the opening degree of the expansion valve is reduced by n, n < m; if no, then the third judgment is made: whether the change value of the low pressure is not less than the fourteenth preset value N.

[0302] In the third judgment, if so, the opening degree of the expansion valve remains unchanged.

[0303] By detecting changes in low-pressure value and controlling the air conditioner to shut down when the low-pressure change is significant, liquid refrigerant can be effectively prevented from flowing back into compressor 14, thus preventing liquid return. When the low-pressure change is small, the opening of the expansion valve is adjusted to reduce the amount of refrigerant entering the float-type gas-liquid separator 16, avoiding liquid return caused by excessive refrigerant failing to vaporize effectively.

[0304] In some embodiments, referring to FIG28, the frequency change value of compressor 14 and the opening change value of expansion valve are obtained within a preset time period. If the frequency change value of compressor 14 does not exceed the fifteenth preset value Y and the opening change value of expansion valve does not exceed the sixteenth preset value Z, the system is considered to be operating stably without change, that is, the air conditioner is operating stably. If the air conditioner does not meet the stable operation conditions, the above-mentioned control of the opening of expansion valve based on the low pressure change value is not entered.

[0305] In some embodiments, the preset time period is 20 seconds. The eleventh preset value K can be 0.1 MPa, the twelfth preset value L can be 0.06 MPa, the thirteenth preset value M can be 0.04 MPa, the fourteenth preset value N can be 0.03 MPa, the fifteenth preset value Y can be 2 Hz, the sixteenth preset value Z can be 1%, m can be 40%, and n can be 20%.

[0306] Referring to Figure 29, the frequency change of compressor 14 is detected before and after 20 seconds. Simultaneously, the opening degree (EVO) of the expansion valve is detected before and after 20 seconds. If H(20s before) - H(20s after) ≤ 2Hz and EVO(20s before) - EVO(20s after) ≤ 1%, the air conditioner operates stably. At this time, it is determined whether the low-pressure change satisfies Ps(20s before) - Ps(20s before) ≥ 0.1MPa. If so, after multiple checks, if Ps(20s before) - Ps(20s before) ≥ 0.1MPa, the air conditioner is shut down. If not, the first check is performed: whether the low-pressure change satisfies Ps(20s before) - Ps(20s before) ≥ 0.06MPa.

[0307] In the first judgment, if yes, then the opening degree of the expansion valve is reduced by m; if no, then the second judgment is made: whether the change value of the low pressure satisfies Ps(20s ago) - Ps(20s ago) ≥ 0.04MPa.

[0308] In the second judgment, if yes, the opening of the expansion valve is reduced by n; if no, the third judgment is made: whether the change value of the low pressure satisfies Ps(20s ago) - Ps(20s ago) ≥ 0.03MPa.

[0309] In the third judgment, if yes, the opening of the expansion valve remains unchanged; if no, the air conditioner is re-judged to determine whether it is operating stably.

[0310] It should be noted that because the low-pressure change is large when the compressor 14 and expansion valve are not operating, it indicates a blockage in the circulation loop of the gas-liquid separator 16. This suggests that the float 420 in the gas-liquid separator 16 has sealed off its pipeline, indicating that the float 420 has risen and the liquid level is high enough to meet the backflow prevention requirements during shutdown. When the low-pressure change is small, the opening of the expansion valve needs to be adjusted. Different heights of the float 420 obstruct airflow, causing changes in low-pressure. Adjusting the opening of the expansion valve can reduce the amount of refrigerant entering the gas-liquid separator 16.

[0311] In some embodiments, the indoor unit 200 may include an indoor expansion valve 23, which reduces the pressure of the refrigerant supplied to the indoor heat exchanger 211 in cooling mode. The outdoor unit 100 may include an outdoor expansion valve 13, which reduces the pressure of the refrigerant supplied to the outdoor heat exchanger of the outdoor unit 100, thereby lowering the temperature of the refrigerant.

[0312] It should be noted that if the air conditioner includes the aforementioned indoor expansion valve 23 and outdoor expansion valve 13, in the above embodiments, in cooling mode, controlling the opening degree of the expansion valve is equivalent to adjusting the opening degree of the indoor expansion valve 23; in heating mode, controlling the opening degree of the expansion valve is equivalent to adjusting the opening degree of the outdoor expansion valve 13. For example, please refer to Figures 30 and 31.

[0313] Some embodiments of this application can effectively solve the problem of excessive liquid return caused by expansion valve control fluctuations when the exhaust superheat of a multi-split air conditioner is low during low-temperature cooling; and the problem of liquid slugging and compressor damage caused by liquid slugging when starting from sleep mode in low-temperature heating mode or after severe defrosting.

[0314] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of some embodiments of this application, and are not intended to limit them. Although some embodiments of this application have been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of some embodiments of this application.

[0315] For ease of explanation, the above description has been provided in conjunction with specific embodiments. However, the above exemplary discussion is not intended to be exhaustive or to limit the embodiments to the specific forms disclosed above. Various modifications and variations can be obtained based on the above teachings. The selection and description of the above embodiments are for the purpose of better explaining the principles and practical applications, thereby enabling those skilled in the art to better utilize the described embodiments and various different variations of embodiments suitable for specific use considerations.

Claims

1. An air conditioner, comprising: A compressor is used to compress refrigerant; An outdoor heat exchanger is used to perform heat exchange between outdoor air and refrigerant; An indoor heat exchanger is used to perform heat exchange between indoor air and refrigerant. The four-way valve has a D port, a C port, an E port and an S port, wherein the D port is connected to the discharge end of the compressor, the C port is connected to the outdoor heat exchanger, the E port is connected to the indoor heat exchanger, and the S port is connected to the suction side of the compressor. A gas-liquid separator is connected between the S-port and the suction side of the compressor to separate the gaseous and liquid states of the refrigerant.

2. The air conditioner according to claim 1, wherein, The gas-liquid separator includes: Tank body; An intake pipe, which is connected to the tank body, is used to deliver refrigerant from the S port into the tank body; An outlet pipe, wherein the intake port of the outlet pipe is located inside the tank, and the outlet port of the outlet pipe extends outside the tank and is connected to the intake side of the compressor, for supplying gaseous refrigerant to the compressor; A shielding device, connected to the tank body, is used to open or cover the air intake port. The shielding device includes: A support plate is rotatably connected to the tank body. The support plate has an open state where the air intake is opened and a covered state where the air intake is covered. A float, which is connected to the support plate, causes the support plate to rotate from an open state to a covered state when the float rises with the liquid refrigerant in the tank.

3. The air conditioner according to claim 2, wherein, When the support plate is in a covered state, the float is lower than the air intake in the height direction.

4. The air conditioner according to claim 2, wherein, The support plate includes: The supporting body is rotatably connected to the air outlet pipe. The cover is connected to the upper end of the supporting body part; The float is connected to the lower part of the supporting body.

5. The air conditioner according to claim 4, wherein, A fixing bracket is connected to the air outlet pipe; The support plate also includes: A support connection portion is connected to the middle part of the support body portion, and one end of the support connection portion away from the support body portion is hinged to the fixing frame.

6. The air conditioner according to claim 4, wherein, The cover has multiple micro-holes. When the support plate is in the covered state, the micro-holes are connected to the air intake, so that the refrigerant can enter the air outlet pipe through the micro-holes.

7. The air conditioner according to claim 2, wherein, The air outlet pipe is provided with a through hole near the air inlet; When the support plate is in a covered state, the through hole is higher than the float in the height direction.

8. The air conditioner according to any one of claims 1 to 7, wherein, A filter screen is installed inside the outlet pipe near the inlet to block liquid refrigerant.

9. The air conditioner according to any one of claims 1 to 7, wherein, A filter is connected to the air outlet pipe near the air inlet, and the filter includes: Pipe section, used for the flow of refrigerant; A filter screen is connected inside the tube.

10. The air conditioner according to claim 8 or 9, wherein, The filter screen is cylindrical, and its cross-section gradually decreases from top to bottom.

11. An air conditioner, comprising: A compressor is used to compress refrigerant; An outdoor heat exchanger is used to perform heat exchange between outdoor air and refrigerant. An indoor heat exchanger is used to perform heat exchange between indoor air and refrigerant. The four-way valve has a D port, a C port, an E port and an S port. The D port is connected to the discharge end of the compressor, the C port is connected to the outdoor heat exchanger, the E port is connected to the indoor heat exchanger, and the S port is connected to the suction side of the compressor. A gas-liquid separator, connected between the S-port and the suction side of the compressor, is used to separate the gaseous and liquid states of the refrigerant. The gas-liquid separator includes: Tank body; An intake pipe, which is connected to the tank body, is used to deliver refrigerant from the S port into the tank body; An outlet pipe, wherein the intake port of the outlet pipe is located inside the tank, and the outlet port of the outlet pipe extends outside the tank and is connected to the intake side of the compressor, for supplying gaseous refrigerant to the compressor; A shielding device is movably connected to the tank body and is used to open or cover the air intake. When the liquid refrigerant in the tank rises to the warning position, the shielding device changes from the open state to the covered state.

12. An air conditioner, comprising: Refrigerant circulation loop; A pressure detection device is used to detect the pressure data of the compressor in real time; A temperature detection device is used to detect the suction temperature of the compressor in real time; The controller is configured to operate during the start-up and transition phases of the air conditioner. Obtain the suction superheat of the compressor; The refrigerant density ρ in the suction pipe is calculated based on the dynamic pressure at the suction port in the pressure data. The suction dryness of the compressor is calculated based on the refrigerant density ρ and refrigerant properties in the suction pipe. The compressor is judged to have a risk of liquid slugging based on the suction superheat and suction dryness. If there is no risk of liquid slugging, the opening of the expansion valve is adjusted according to the preset control logic; if there is a risk of liquid slugging, the level of liquid slugging risk is determined. If the liquid hammer risk level is level one, then control the opening of the expansion valve to decrease to the first opening degree; If the liquid hammer risk level is level two, then control the opening of the expansion valve to decrease to the second opening degree; If the liquid slugging risk level is level three, then control the air conditioner to shut down; The return liquid volume of the third level, the return liquid volume of the second level, and the return liquid volume of the first level are different from each other, and the first opening degree is different from the second opening degree.

13. The air conditioner according to claim 12, wherein, In the refrigerant circulation loop, the refrigerant circulates sequentially through the compressor, condenser, expansion valve, and evaporator. One of the condenser and the evaporator is an outdoor heat exchanger, and the other is an indoor heat exchanger.

14. The air conditioner according to claim 12, wherein, The return volume of the third level is greater than that of the second level, the return volume of the second level is greater than that of the first level, and the opening degree of the first level is greater than that of the second level.

15. The air conditioner according to claim 12, wherein, The controller is configured to: If the intake superheat is not less than the first preset value A, or the intake dryness exceeds the second preset value B, then it is determined that the compressor does not have a risk of liquid slugging. If the superheat of the intake air is less than the first preset value A and not less than the fourth preset value W, or if the dryness of the intake air is not greater than the second preset value B, it is determined whether the dryness of the intake air is not less than the third preset value C. If so, the liquid hammer risk level is determined to be the first level, and the opening of the expansion valve is controlled to be reduced to the first opening. If not, the liquid hammer risk level is determined to be the second level, and the opening degree of the expansion valve is controlled to decrease Q to the second opening degree; If the intake superheat is less than the fourth preset value W, determine whether the intake dryness exceeds the preset threshold D. If yes, determine the liquid slugging risk level as the second level and control the opening of the expansion valve to decrease Q to the second opening. If no, determine the liquid slugging risk level as the third level and control the air conditioner to stop. Wherein, the preset threshold D < the third preset value C.

16. The air conditioner according to any one of claims 12 to 15, wherein, The temperature detection device is also used to detect the discharge temperature of the compressor in real time, and the controller is configured to: During the stable operation phase of the air conditioner, the intake superheat, the change in intake superheat, the exhaust superheat, and the change in exhaust superheat are obtained. The presence of liquid slugging risk in the compressor is determined based on the intake superheat and its change or the exhaust superheat and its change. If there is no risk of liquid slugging, the opening of the expansion valve is adjusted according to the preset control logic; if there is a risk of liquid slugging, the liquid slugging risk level of the compressor is determined. If the liquid hammer risk level is the first level, then control the opening degree of the expansion valve to decrease by P; If the liquid hammer risk level is the second level, then control the opening of the expansion valve to decrease by Q, where Q > P; If the liquid slugging risk level is the third level, then the air conditioner is shut down.

17. The air conditioner according to claim 16, wherein, The controller is configured to: If the intake superheat is not less than the first preset value A, it is determined that the compressor does not have a risk of liquid slugging, and the opening of the expansion valve is adjusted according to the preset control logic. If the intake superheat is greater than the fifth preset value E and less than the first preset value A, then determine whether the change in intake superheat is not less than the fourth preset value W; if yes, then determine that the liquid hammer risk level is the first level, and at this time control the opening of the expansion valve to decrease by P; if no, then determine that the liquid hammer risk level is the second level, and at this time control the opening of the expansion valve to decrease by Q. If the intake superheat is greater than the sixth preset value F and not greater than the fifth preset value E, then the liquid hammer risk level is determined to be the second level, and the opening of the expansion valve is controlled to decrease by Q. If the intake superheat is not greater than the sixth preset value F, the liquid slugging risk level is determined to be level three, and the air conditioner is controlled to shut down.

18. The air conditioner according to claim 16, wherein, The controller is configured to: If the exhaust superheat is not less than the seventh preset value G, it is determined that the compressor does not have a risk of liquid slugging. At this time, the opening of the expansion valve is adjusted according to the preset control logic. If the exhaust superheat is greater than the eighth preset value H and less than the seventh preset value G, then determine whether the change in exhaust superheat is not less than the fourth preset value W; if yes, then determine that the liquid hammer risk level is the first level, and at this time control the opening of the expansion valve to decrease by P; if no, then determine that the liquid hammer risk level is the second level, and at this time control the opening of the expansion valve to decrease by Q. If the exhaust superheat is greater than the ninth preset value I and not greater than the eighth preset value H, then the liquid hammer risk level is determined to be the second level, and the opening of the expansion valve is controlled to decrease by Q. If the exhaust superheat is not greater than the ninth preset value I, the liquid slugging risk level is determined to be level three, and the air conditioner is controlled to stop.

19. The air conditioner according to any one of claims 12 to 15, wherein, The temperature detection device is also used to detect the discharge temperature of the compressor in real time, and the controller is configured to: During the stable operation phase of the air conditioner, the exhaust superheat and intake superheat of the compressor are obtained; Based on the exhaust superheat and intake superheat, determine whether the compressor has a risk of liquid slugging; If there is no risk of liquid slugging, the opening of the expansion valve is adjusted according to the preset control logic; if there is a risk of liquid slugging, the liquid slugging risk level of the compressor is determined. If the liquid hammer risk level is the first level, then control the opening degree of the expansion valve to decrease by P; If the liquid hammer risk level is the second level, then control the opening degree of the expansion valve to decrease by Q, P < Q; If the liquid slugging risk level is the third level, then the air conditioner is shut down.

20. The air conditioner according to claim 19, wherein, The controller is configured to: If the exhaust superheat is not less than the seventh preset value G, it is determined that the compressor does not have a risk of liquid slugging. At this time, the opening of the expansion valve is adjusted according to the preset control logic. If the exhaust superheat is greater than the tenth preset value J and less than the seventh preset value G, then determine whether the intake superheat is not less than the first preset value A. If yes, the liquid hammer risk level is determined to be Level 1, and the opening degree of the expansion valve is reduced by P; if no, the liquid hammer risk level is determined to be Level 2, and the opening degree of the expansion valve is reduced by Q. If the exhaust superheat is not greater than the tenth preset value J, then the change in the intake superheat is obtained and it is determined whether it is not less than the fourth preset value W; if so, then the liquid slugging risk level is determined to be the second level, and at this time, the opening of the expansion valve is controlled to decrease Q; if not, then the liquid slugging risk level is determined to be the third level, and at this time, the air conditioner is controlled to stop.

21. The air conditioner according to claim 12, wherein, The refrigerant circulation loop also includes a float-type gas-liquid separator connected in series between the compressor's suction port and the evaporator's outlet, the pressure data includes low-pressure, and the controller is configured to: When the air conditioner is running stably, the low-pressure change value is obtained within a preset time period; The opening degree of the expansion valve is adjusted according to the low-pressure change value.

22. The air conditioner according to claim 21, wherein, The controller is configured to: Determine whether the low-pressure change value is not less than the eleventh preset value K. If yes, perform multiple determinations and if the result is still yes, control the air conditioner to stop. If no, perform the first determination: whether the low-pressure change value is not less than the twelfth preset value L. In the first judgment, if yes, then control the opening degree of the expansion valve to decrease by m; if no, then perform the second judgment: whether the low pressure change value is not less than the thirteenth preset value M. In the second judgment, if yes, then control the opening degree of the expansion valve to decrease by n, n < m; if no, then perform the third judgment: whether the low pressure change value is not less than the fourteenth preset value N. If the third determination is true, then the opening degree of the expansion valve remains unchanged.

23. An air conditioner, comprising: The refrigerant circulation loop, in which the refrigerant circulates sequentially through the compressor, condenser, expansion valve, and evaporator, wherein one of the condenser and the evaporator is an outdoor heat exchanger and the other is an indoor heat exchanger; A pressure detection device is used to detect the pressure data of the compressor in real time; A temperature detection device is used to detect the suction temperature of the compressor in real time; The controller is configured to operate during the start-up and transition phases of the air conditioner. Obtain the suction superheat of the compressor; The refrigerant density ρ in the suction pipe is calculated based on the dynamic pressure of the suction port in the pressure data, and the suction dryness of the compressor is calculated based on the refrigerant density ρ in the suction pipe and the refrigerant physical property parameters. The presence and level of liquid slugging risk in the compressor are determined based on the intake superheat and intake dryness. If there is no risk of liquid slugging, the opening degree of the expansion valve is adjusted according to the preset control logic; If the liquid slugging risk level is level three, then control the air conditioner to shut down; If the liquid hammer risk level is level two, then control the opening degree of the expansion valve to decrease by Q; If the liquid hammer risk level is level one, then control the opening degree of the expansion valve to decrease by P; Where P < Q, the return volume of the third level is greater than the return volume of the second level, and the return volume of the second level is greater than the return volume of the first level.

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