Multi-split air conditioner

Abstract

The invention discloses a multi-split air conditioner which comprises an indoor unit provided with an indoor heat exchanger, an indoor fan and an indoor unit expansion valve used for controlling the refrigerant flow, an outdoor unit provided with a compressor, an outdoor heat exchanger, an outdoor fan and an outdoor unit expansion valve used for controlling the refrigerant flow, and a controller. When the multi-split air conditioner executes a heating mode before being shut down, after the multi-split air conditioner is shut down, the indoor fan and the outdoor fan are shut down; after the outdoor unit expansion valve is closed for a first preset duration t1, the opening degree of the outdoor unit expansion valve is adjusted to a first preset opening degree, and the outdoor unit expansion valve is closed after working for a period of time; the indoor unit expansion valves of all the indoor units are opened to a second preset opening degree, the opening degrees of the indoor unit expansion valves are intermittently reduced along with the increase of the shutdown time, and after the working duration of the indoor unit expansion valves reaches a third preset duration t3 after the indoor unit expansion valves are automatically shut down, the opening degrees of the indoor unit expansion valves are adjusted to the maximum opening degree; all the indoor unit expansion valves and all the outdoor unit expansion valves are used for pressure equalizing, system pipelines are simple, and the pressure equalizing speed is high.

Description

Technical Field

[0001] The present invention belongs to the technical field of air conditioners, and particularly relates to a multi-connected air conditioner. Background Art

[0002] When a multi-connected air conditioner is turned on, when the starting pressure difference of the compressor exceeds a certain range, the starting torque of the compressor is less than the sum of the starting pressure difference torque and the frictional resistance torque, resulting in a locked-rotor phenomenon, which causes the starting current and power value to be abnormally high. This will lead to two results. First, the motor coil will generate a large amount of heat, affecting the insulation performance of the enameled wire of the compressor and even burning out the coil. Second, the high power value and current value will increase the load of the power supply and the circuit. If it exceeds its bearing range, it will lead to accidents.

[0003] Regarding the problem of pressure difference starting of the compressor, a pressure balancing device (generally a bypass branch) is added to the suction pipeline and the exhaust pipeline of the air conditioning system. The air conditioning system diagram is referred to Figure 1 , and the pressure balancing device consists of a capillary tube, a solenoid valve and a filter. After shutdown, the solenoid valve is opened to ensure that the high and low pressures of the system can be quickly balanced after the compressor stops working. Although this method can solve the problems caused by the pressure difference during air conditioner shutdown, it increases the design complexity of the air conditioning system and the pipeline, and will increase the production cost.

[0004] In order to balance the pressure difference of the air conditioning system and the actual application situation, in the related art, the bypass branch is cancelled, and the expansion valves of the outdoor unit and the indoor units in the on state are used for pressure equalization. This will cause the pressure equalization to not be completed within the preset time when the pressure difference of the compressor is large, resulting in a start-up failure due to excessive pressure difference, affecting the use and reliability of the multi-connected air conditioner.

[0005] In view of this, the present application is proposed. Summary of the Invention

[0006] Aiming at the problem of slow pressure equalization speed in the related art, the present application proposes a multi-connected air conditioner, which realizes rapid pressure equalization by adjusting the opening degree of the indoor expansion valves of all indoor units after shutdown.

[0007] An embodiment of the present application proposes a multi-connected air conditioner, which includes:

[0008] An outdoor unit, which includes:

[0009] An outdoor housing;

[0010] A compressor, which has a suction port and an exhaust port;

[0011] An outdoor heat exchanger, which is arranged in the outdoor housing and is used for heat exchange with outdoor air;

[0012] An outdoor fan, whose rotation causes outdoor air to enter the outdoor housing, and the outdoor air flows out of the outdoor housing after exchanging heat with the outdoor heat exchanger;

[0013] An outdoor expansion valve, which is connected to the outdoor heat exchanger and is used to adjust the refrigerant flow rate in the air-conditioning system;

[0014] An indoor unit, which includes a plurality of indoor machines, and the indoor machine includes:

[0015] An indoor housing;

[0016] An indoor heat exchanger, which is arranged in the indoor housing and is used to exchange heat with indoor air;

[0017] An indoor fan, whose rotation causes indoor air to enter the indoor housing, and the indoor air flows out of the indoor housing after exchanging heat with the indoor heat exchanger;

[0018] An indoor expansion valve, which is connected to the indoor heat exchanger and is used to adjust the refrigerant flow rate in the air-conditioning system;

[0019] The multi-connected air conditioner further includes:

[0020] A controller, which is at least used to control the compressor, indoor fan, outdoor fan, outdoor expansion valve and indoor expansion valve;

[0021] The controller is configured to: when the multi-connected air conditioner executes the heating mode before shutdown, after shutdown, the indoor fan is turned off to stop the indoor machine from continuing to blow air into the room; the outdoor fan is turned off;

[0022] After the outdoor expansion valve is closed for the first preset duration t1, the opening degree of the outdoor expansion valve is adjusted to the first preset opening degree, and the outdoor expansion valve works at the first preset opening degree for the second preset duration t2 and then is closed;

[0023] The indoor expansion valves of all indoor machines are all opened to the second preset opening degree. As the shutdown time increases, the opening degree of the indoor expansion valve decreases intermittently. When the working duration of the indoor expansion valve after shutdown reaches the third preset duration t3, the opening degree of the indoor expansion valve is adjusted to the maximum opening degree;

[0024] Wherein, the second preset opening degree is smaller than the maximum opening degree.

[0025] In some embodiments, when the multi-connected air conditioner executes the heating mode and after shutdown, the controller is configured to:

[0026] The opening degrees of the indoor expansion valves of all indoor machines are adjusted to the second preset opening degree. After working for the fourth preset duration t4, the opening degrees of the indoor expansion valves are adjusted to the third preset opening degree, and then continue to decrease intermittently at a preset time interval until the working duration of the indoor expansion valve after shutdown reaches the third preset duration t3, and the opening degrees of the indoor expansion valves are adjusted to the maximum opening degree;

[0027] Wherein, the third preset opening degree is less than the second preset opening degree, and t4 = t2.

[0028] In some embodiments, the controller is further configured to:

[0029] When the multi-connected air conditioner executes the cooling mode, after shutdown, the indoor fan and the outdoor fan stop rotating to stop the indoor unit from continuing to blow air into the room;

[0030] The outdoor expansion valve always maintains the maximum opening degree; the indoor expansion valve is adjusted to the fourth preset opening degree, and as the shutdown time increases, the opening degree of the indoor expansion valve is intermittently reduced until the opening degree of the indoor expansion valve is reduced to the fifth preset opening degree and stops further decreasing and remains at this opening degree;

[0031] Wherein, the fourth preset opening degree is less than the maximum opening degree, and the fifth preset opening degree is greater than 0%.

[0032] In some embodiments, the fourth preset opening degree is less than the second preset opening degree to reduce the flow sound of the liquid refrigerant in the cooling mode.

[0033] In some embodiments, the controller is configured to: when shutting down the multi-connected air conditioner, first shut down the corresponding indoor unit, and then shut down the outdoor unit;

[0034] When the indoor unit is shut down and the outdoor unit is turned on, the indoor fan and the outdoor fan remain in the working state;

[0035] When the outdoor unit is shut down, the indoor fan and the outdoor fan stop rotating.

[0036] In some embodiments, the multi-connected air conditioner further includes:

[0037] A first pressure detection device, which is arranged at the suction port of the compressor and is used to detect the first pressure value at the suction port of the compressor;

[0038] A second pressure detection device, which is arranged at the discharge port of the compressor and is used to detect the second pressure value at the discharge port of the compressor;

[0039] The controller is further configured to: after the multi-connected air conditioner is shut down, obtain a pressure difference, where the pressure difference is the absolute value of the difference between the first pressure value and the second pressure value, and when the pressure difference exceeds a preset pressure difference, perform a pressure equalization operation.

[0040] In some embodiments, the controller is further configured to: when the pressure difference does not exceed the preset pressure difference, do not perform a pressure equalization operation.

[0041] The present application also proposes another multi-connected air conditioner, which includes:

[0042] An outdoor unit, which includes:

[0043] An outdoor housing;

[0044] A compressor having a suction port and a discharge port;

[0045] An outdoor heat exchanger provided in an outdoor housing for exchanging heat with outdoor air;

[0046] An outdoor fan whose rotation causes outdoor air to enter the outdoor housing, and the outdoor air flows out of the outdoor housing after exchanging heat with the outdoor heat exchanger;

[0047] An outdoor expansion valve communicating with the outdoor heat exchanger for regulating the refrigerant flow rate in the air-conditioning system;

[0048] An indoor unit including a plurality of indoor machines, and each indoor machine includes:

[0049] An indoor housing;

[0050] An indoor heat exchanger provided in the indoor housing for exchanging heat with indoor air;

[0051] An indoor fan whose rotation causes indoor air to enter the indoor housing, and the indoor air flows out of the indoor housing after exchanging heat with the indoor heat exchanger;

[0052] An indoor expansion valve communicating with the indoor heat exchanger for regulating the refrigerant flow rate in the air-conditioning system;

[0053] The multi-connected air conditioner further includes:

[0054] A controller for at least controlling the compressor, the indoor fan, the outdoor fan, the outdoor expansion valve, and the indoor expansion valve;

[0055] The controller is configured to: when the multi-connected air conditioner executes the heating mode before shutdown, after shutdown, the indoor fan is turned off to stop the indoor machine from continuing to blow air into the room; the outdoor fan is turned off;

[0056] The outdoor expansion valve is adjusted to a sixth preset opening degree, and after working for a period of time, the outdoor expansion valve is closed;

[0057] The indoor expansion valves of all indoor machines are all opened to a seventh preset opening degree. As the shutdown time increases, the opening degree of the indoor expansion valve decreases intermittently. After the working duration of the indoor expansion valve reaches a fifth preset duration t5 after shutdown, the opening degree of the indoor expansion valve is adjusted to the maximum opening degree;

[0058] Wherein, the seventh preset opening degree is less than the maximum opening degree.

[0059] In some embodiments, the controller is configured to: when shutting down the multi-connected air conditioner, first shut down the corresponding indoor machine, and then shut down the outdoor machine;

[0060] When the indoor machine is turned off and the outdoor machine is turned on, the indoor fan and the outdoor fan remain in the working state;

[0061] When the outdoor unit shuts down, the indoor fan and the outdoor fan stop rotating.

[0062] Another multi-connected air conditioner is also proposed in this application. The multi-connected air conditioner includes:

[0063] An outdoor unit, which includes:

[0064] An outdoor housing;

[0065] A compressor, which has a suction port and a discharge port;

[0066] An outdoor heat exchanger, which is arranged in the outdoor housing and is used for heat exchange with outdoor air;

[0067] An outdoor fan, whose rotation causes outdoor air to enter the outdoor housing, and the outdoor air flows out of the outdoor housing after heat exchange with the outdoor heat exchanger;

[0068] An outdoor expansion valve, which is communicated with the outdoor heat exchanger and is used for adjusting the refrigerant flow rate in the air-conditioning system;

[0069] An indoor unit group, which includes a plurality of indoor units. The indoor unit includes:

[0070] An indoor housing;

[0071] An indoor heat exchanger, which is arranged in the indoor housing and is used for heat exchange with indoor air;

[0072] An indoor fan, whose rotation causes indoor air to enter the indoor housing, and the indoor air flows out of the indoor housing after heat exchange with the indoor heat exchanger;

[0073] An indoor expansion valve, which is communicated with the indoor heat exchanger and is used for adjusting the refrigerant flow rate in the air-conditioning system;

[0074] The multi-connected air conditioner further includes:

[0075] A controller, which is at least used for controlling the compressor, the indoor fan, the outdoor fan, the outdoor expansion valve and the indoor expansion valve;

[0076] The controller is configured to: when the multi-connected air conditioner executes the cooling mode before shutdown, after shutdown, the indoor fan and the outdoor fan stop rotating to stop the indoor unit from continuing to blow air into the room;

[0077] The outdoor expansion valve always maintains the maximum opening degree; the indoor expansion valve is adjusted to the fourth preset opening degree, and as the shutdown time increases, the opening degree of the indoor expansion valve is intermittently reduced until the opening degree of the indoor expansion valve is reduced to the fifth preset opening degree and stops continuing to decrease and maintains this opening degree;

[0078] Wherein, the fourth preset opening degree is less than the maximum opening degree, and the fifth preset opening degree is greater than 0%.

[0079] In the multi-connected air conditioner proposed in the above embodiments, the opening degrees of the indoor expansion valves of all indoor units are adjusted to accelerate the pressure averaging of the suction port and the discharge port of the compressor. At the same time, after shutdown, the indoor fan is stopped to operate, so as to avoid the temperature of the indoor heat exchanger rising or falling after the compressor stops, resulting in the air blown out by the indoor unit deviating from the set temperature and affecting the user experience. Also, the outdoor fan is stopped to prevent creating an illusion for the user that the multi-connected air conditioner has not been successfully shut down, which may cause the user to repeatedly issue commands and affect the user experience. BRIEF DESCRIPTION OF THE DRAWINGS

[0080] The drawings described herein are used to provide a further understanding of the present invention, and constitute a part of this application. The schematic embodiments of the present invention and their descriptions are used to explain the present invention, and do not constitute an improper limitation to the present invention. In the drawings:

[0081] Figure 1 is a structural block diagram of a multi-connected air conditioner in an embodiment of the present invention;

[0082] Figure 2 is a system block diagram of an air conditioning system in an embodiment of the present invention;

[0083] Figure 3 is a hardware block diagram of a controller in an embodiment of the present invention;

[0084] Figure 4 is a timing diagram of the indoor fan and the outdoor fan when the heating mode is executed before shutdown in an embodiment of the present invention;

[0085] Figure 5 is a timing diagram of an indoor expansion valve when the heating mode is executed before shutdown in an embodiment of the present invention;

[0086] Figure 6 is a timing diagram of an outdoor expansion valve when the heating mode is executed before shutdown in an embodiment of the present invention;

[0087] Figure 7 is a flowchart of a differential pressure balancing method when the heating mode is executed before shutdown in an embodiment of the present invention;

[0088] Figure 8 is another timing diagram of an indoor expansion valve when the heating mode is executed before shutdown in an embodiment of the present invention;

[0089] Figure 9 is another flowchart of a differential pressure balancing method when the heating mode is executed before shutdown in an embodiment of the present invention

[0090] Figure 10 is a timing diagram of the indoor fan and the outdoor fan when the cooling mode is executed before shutdown in an embodiment of the present invention;

[0091] Figure 11 It is the timing diagram of the outdoor unit expansion valve when the refrigeration mode is executed before shutdown in an embodiment of the present invention;

[0092] Figure 12 It is the timing diagram of the indoor unit expansion valve when the refrigeration mode is executed before shutdown in an embodiment of the present invention;

[0093] Figure 13 It is the flowchart of the differential pressure balance method when the refrigeration mode is executed before shutdown in an embodiment of the present invention

[0094] Figure 14 It is another timing diagram of the indoor unit expansion valve when the heating mode is executed before shutdown in an embodiment of the present invention;

[0095] Figure 15 It is another timing diagram of the outdoor unit expansion valve when the heating mode is executed before shutdown in an embodiment of the present invention;

[0096] In the above figures:

[0097] Multi-connected air conditioner 100; indoor unit 10; indoor unit 1; outdoor unit 2; indoor fan 11; four-way valve 25

[0098] Indoor heat exchanger 12; indoor unit expansion valve 13; outdoor fan 26; outdoor heat exchanger 22; outdoor unit expansion valve 23;

[0099] Compressor 24; controller 21; bus 211; memory 212; processor 213; communication interface 214. Detailed implementation manners

[0100] Next, the technical solutions in the embodiments will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0101] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "lateral", "longitudinal", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0102] In the description of the present invention, it should be noted that unless otherwise clearly specified and limited, the terms "installation", "connection", and "coupling" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected, or indirectly connected through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0103] This application proposes a multi-connected air conditioner 100. Referring to Figure 1 , the multi-connected air conditioner 100 includes an indoor unit 10, and the indoor unit 10 includes a plurality of parallel indoor units 1.

[0104] The multi-connected air conditioner 100 includes an outdoor unit 2. The outdoor unit 2 is installed outdoors. The indoor unit 1 and the outdoor unit 2 are connected through pipelines for the refrigerant to flow.

[0105] The indoor unit 1 includes an indoor housing. The indoor housing is used to form the outer contour of the indoor unit 1 and accommodate the internal components of the indoor unit 1.

[0106] The indoor housing has an indoor air inlet. The indoor air inlet is used for indoor air to enter the indoor housing.

[0107] The indoor housing has an indoor air outlet. The indoor air outlet is used for the air in the indoor housing to be discharged. The indoor air enters the indoor housing through the indoor air inlet and then blows out from the indoor air outlet.

[0108] The indoor unit 1 includes an indoor heat exchanger 12. The indoor heat exchanger 12 is installed inside the indoor housing. The indoor heat exchanger 12 is used for heat exchange with the indoor air entering the indoor housing.

[0109] The indoor unit 1 includes an indoor fan 11. The indoor fan 11 is installed inside the indoor housing. The indoor fan 11 rotates to make the indoor air enter the indoor housing, and the indoor air exchanges heat with the indoor heat exchanger 12 and then flows out of the indoor housing.

[0110] In this application, the indoor unit 1 includes but is not limited to a wall-mounted air conditioner, a cabinet air conditioner, and a ducted air conditioner.

[0111] The outdoor unit 2 includes an outdoor housing. The outdoor housing is used to form the outer contour of the outdoor unit 2 and accommodate the internal components of the outdoor unit 2.

[0112] The outdoor housing has an outdoor air inlet. The outdoor air inlet is used for outdoor air to enter the outdoor housing.

[0113] The outdoor housing has an outdoor air outlet. The outdoor air outlet is used for the air in the outdoor housing to be discharged. The outdoor air enters the outdoor housing through the outdoor air inlet and then blows out from the outdoor air outlet.

[0114] The outdoor unit 2 includes an outdoor heat exchanger 22, which is installed inside the outdoor housing and is used for heat exchange with the outdoor air entering the outdoor housing.

[0115] The outdoor unit 2 includes an outdoor fan 26, which is installed inside the outdoor housing. The outdoor fan 26 rotates to make the outdoor air enter the outdoor housing, and the outdoor air flows out of the outdoor housing after heat exchange with the outdoor heat exchanger 22.

[0116] In some embodiments, the multi - split air conditioner 100 includes an air - conditioning system.

[0117] The air - conditioning system includes a compressor 24. The compressor 24 can compress the refrigerant gas in a high - temperature and high - pressure state and discharge the compressed refrigerant gas.

[0118] The compressor 24 includes a suction port.

[0119] The compressor 24 includes a discharge port. The refrigerant flows back into the compressor 24 through the suction port and flows out of the compressor 24 through the discharge port.

[0120] The air - conditioning system includes a condenser. The condenser can use the latent heat of condensation of the refrigerant to exchange heat with the material to be cooled to achieve a refrigeration effect.

[0121] The air - conditioning system includes an expansion valve. During the refrigeration operation, the expansion valve controls the refrigerant flow rate from the outdoor heat exchanger 22 to the indoor heat exchanger 12 by adjusting its own opening degree.

[0122] The air - conditioning system includes an evaporator. The evaporator can use the latent heat of evaporation of the refrigerant to exchange heat with the material to be cooled to achieve a refrigeration effect.

[0123] The refrigerant gas discharged from the discharge port of the compressor 24 flows into the condenser. The condenser condenses the compressed refrigerant into a liquid phase and releases the heat to the surrounding environment through the condensation process.

[0124] The expansion valve expands the high - temperature and high - pressure liquid - phase refrigerant condensed in the condenser into a low - pressure liquid - phase refrigerant. The evaporator evaporates the refrigerant expanded in the expansion valve and returns the low - temperature and low - pressure refrigerant gas to the suction port of the compressor 24.

[0125] The indoor heat exchanger 12 and the outdoor heat exchanger 22 are used as condensers or evaporators. When the indoor heat exchanger 12 is used as a condenser, the air conditioner serves as a heater in the heating mode. When the indoor heat exchanger 12 is used as an evaporator, the air conditioner serves as a cooler in the cooling mode.

[0126] The multi-connected air conditioner 100 blows air-conditioning wind that is higher than the indoor temperature, lower than the indoor temperature, or the same as the indoor temperature by means of refrigerant flow, so as to adjust the temperature and humidity of the indoor environment; or adjusts the air flow rate of the indoor environment by means of the rotation speed of the indoor fan 11.

[0127] Taking one of the indoor units 1 as an example, the cooling mode and heating mode of the multi-connected air conditioner 100 will be described.

[0128] When the multi-connected air conditioner 100 operates in cooling mode, the refrigerant compressed by the compressor 24 flows through the outdoor heat exchanger 22 and condenses, and the condensed refrigerant expands by flowing through the expansion valve. The expanded refrigerant evaporates through the indoor heat exchanger 12. Then, the evaporated refrigerant circulates back to the compressor 24.

[0129] When the multi-connected air conditioner 100 operates in heating mode, the refrigerant compressed by the compressor 24 flows through the indoor heat exchanger 12 and condenses, and the condensed refrigerant expands by flowing through the expansion valve. The refrigerant after the expansion valve evaporates through the outdoor heat exchanger 22. Then, the evaporated refrigerant circulates back to the compressor 24.

[0130] After the multi-connected air conditioner 100 stops, if the multi-connected air conditioner 100 operates in cooling mode before stopping, the pressure in the pipeline of the outdoor unit 2 will be greater than the pressure in the pipeline of the indoor unit 1. On the contrary, if the multi-connected air conditioner 100 operates in heating mode before stopping, the pressure in the pipeline of the outdoor unit 2 will be less than the pressure in the pipeline of the indoor unit 1.

[0131] That is to say, whether the multi-connected air conditioner 100 operates in heating mode or cooling mode before stopping, after the multi-connected air conditioner 100 stops, the pressures of the pipelines of the outdoor unit 2 and the indoor unit 1 will be unbalanced. That is, there will be a pressure difference between the outdoor unit 2 and the indoor unit 1 for a period of time after the multi-connected air conditioner 100 stops. And the pressure difference will cause the compressor 24 to be unable to start due to insufficient torque, affecting the normal operation of the multi-connected air conditioner 100.

[0132] When all components of the multi-connected air conditioner 100 work normally, this pressure difference will slowly balance with the flow of the refrigerant in the pipeline of the multi-connected air conditioner 100, but the balance speed is slow.

[0133] In some embodiments, a bypass pipeline is provided between the exhaust port and the suction port of the compressor 24 to accelerate the flow efficiency of the refrigerant in the pipeline of the multi-connected air conditioner 100 and improve the balance speed of this pressure difference.

[0134] However, setting a bypass pipeline between the exhaust port and the suction port of the compressor 24 will increase the complexity of the pipeline of the outdoor unit 2. For example, it will increase solder joints, fixing blocks, wire ties, etc., resulting in a reduction in the production efficiency of the multi-connected air conditioner 100 and an increase in production costs.

[0135] In some embodiments of the present application, the expansion valve includes an indoor expansion valve 13. The indoor expansion valve 13 is disposed in the indoor unit 1 and is used to adjust the refrigerant flow rate in the air-conditioning system.

[0136] In some embodiments of the present application, the expansion valve includes an outdoor expansion valve 23. The outdoor expansion valve 23 is disposed in the outdoor unit 2 and is used to adjust the refrigerant flow rate in the air-conditioning system.

[0137] In some embodiments of the present application, the expansion valve includes an indoor expansion valve 13 and an outdoor expansion valve 23. The indoor expansion valve 13 is disposed in the indoor unit 1, and the outdoor expansion valve 23 is disposed in the outdoor unit 2.

[0138] The refrigerant flow rate between the indoor heat exchanger 12 and the outdoor heat exchanger 22 is jointly controlled by the indoor expansion valve 13 and the outdoor expansion valve 23 to quickly balance the pressures at the suction port and the discharge port of the compressor 24.

[0139] In the air-conditioning system of the multi-connected air conditioner 100 of the present application, it is used to exchange heat with indoor air to meet the cooling or heating requirements.

[0140] The refrigerant gas discharged from the discharge port of the compressor 24 flows into the condenser. The condenser condenses the compressed refrigerant into a liquid phase and releases the heat to the surrounding environment through the condensation process.

[0141] The indoor expansion valve 13 and / or the outdoor expansion valve 23 expand the liquid-phase refrigerant in a high-temperature and high-pressure state condensed in the condenser into a low-pressure liquid-phase refrigerant. The evaporator evaporates the refrigerant expanded in the indoor expansion valve 13 and / or the outdoor expansion valve 23 and returns the refrigerant gas in a low-temperature and low-pressure state to the suction port of the compressor 24.

[0142] Refer to Figure 2 to illustrate the system configuration of the air-conditioning system in the present application.

[0143] The air-conditioning system includes a four-way valve 25. The first interface of the four-way valve 25 is communicated with the discharge port of the compressor 24. The second interface of the four-way valve 25 is communicated with the suction port of the compressor 24. The third interface of the four-way valve 25 is communicated with one end of each indoor heat exchanger 12. The fourth interface of the four-way valve 25 is communicated with one end of the outdoor heat exchanger 22.

[0144] The other end of the outdoor heat exchanger 22 is communicated with one end of the outdoor expansion valve 23. The other end of the outdoor expansion valve 23 is communicated with one end of a plurality of indoor expansion valves 13, and the other ends of the plurality of indoor expansion valves 13 are respectively and correspondingly communicated with the other ends of the plurality of indoor heat exchangers 12.

[0145] In some embodiments of the present application, the multi-split air conditioner 100 further includes a control device. The control device is configured to send instructions to the multi-split air conditioner 100 to control the working process of the multi-split air conditioner 100.

[0146] In some embodiments of the present application, the multi-split air conditioner 100 includes a remote controller. The user inputs instructions to the controller 21 through the remote controller to select the working modes of the indoor unit 1 and the outdoor unit 2.

[0147] In some embodiments, the working modes of the multi-split air conditioner 100 are diverse according to different models and user requirements. In the present application, the cooling mode, the heating mode, and the shutdown state are selected for introduction.

[0148] Among them, in the cooling mode, the air flowing from the indoor unit 1 into the room is cold air. The above-mentioned cold air can be defined as an air flow with a temperature lower than the indoor air temperature.

[0149] In the heating mode, the air flowing from the indoor unit 1 into the room is hot air. The above-mentioned hot air can be defined as an air flow with a temperature higher than the indoor air temperature. The heating mode and the cooling mode belong to the common knowledge of those skilled in the art.

[0150] In the shutdown mode, the multi-split air conditioner 100 does not improve parameters such as the indoor temperature, humidity, and air flow velocity.

[0151] In some embodiments of the present application, the multi-split air conditioner 100 includes a controller 21.

[0152] The controller 21 includes an indoor controller 21. The indoor controller 21 is installed in the indoor unit 1. The indoor controller 21 can be used to control the working states of the components inside the indoor unit 1.

[0153] The controller 21 includes an outdoor controller 21. The outdoor controller 21 is installed in the outdoor unit 2. The outdoor controller 21 can be used to control the working states of the components inside the outdoor unit 2.

[0154] Wired communication is adopted between the outdoor controller 21 and the compressor 24, between the outdoor controller 21 and the outdoor expansion valve 23, and between the indoor controller 21 and the indoor expansion valve 13. That is, communication is carried out through wires to ensure communication quality and reduce the production cost of the multi-split air conditioner 100.

[0155] Wired communication is adopted between the indoor controller 21 and the outdoor controller 21.

[0156] In other embodiments, the above-mentioned communication method can also be wireless communication.

[0157] In the present application, the outdoor controller 21 and the indoor controller 21 are configured to control the opening degrees of respective expansion valves according to the operating conditions of the multi-connected air conditioner 100 before receiving the shutdown instruction, so as to increase the speed of differential pressure balance after the multi-connected air conditioner 100 shuts down.

[0158] For the opening degree of the outdoor expansion valve 23, the outdoor controller 21 can directly control it. For the shutdown instruction, the outdoor controller 21 can directly receive it. For the opening degree of the indoor expansion valve 13, the outdoor controller 21 can indirectly control it according to the indoor controller 21.

[0159] In other embodiments, it may also be that one of the indoor controllers 21 is configured to receive the shutdown instruction and control the opening degrees of respective expansion valves according to the operating conditions of the multi-connected air conditioner 100 before receiving the shutdown instruction, so as to increase the speed of differential pressure balance after the multi-connected air conditioner 100 shuts down.

[0160] For the opening degree of the indoor expansion valve 13, the indoor controller 21 can directly control it. For the opening degree of the indoor expansion valve 13, the indoor controller 21 can control it through the outdoor controller 21. For the shutdown signal, it can be received by the outdoor controller 21 and then forwarded to the indoor controller 21.

[0161] In some embodiments of the present application, the indoor controller 21 and the outdoor controller 21 are not specifically distinguished, and the indoor controller 21 and the outdoor controller 21 are collectively referred to as the controller 21.

[0162] The controller 21 is configured to coordinate the operation of the entire multi-connected air conditioner 100, including receiving user instructions, operating in refrigeration mode, heating mode, blowing mode, etc., and uploading the working state of the multi-connected air conditioner 100 to the cloud, etc.

[0163] The structures of the indoor controller 21 and the outdoor controller 21 are substantially the same. Taking the indoor controller 21 as an example, its structure is described.

[0164] The indoor controller 21 includes a memory 212. The memory 212 may include a high-speed random access memory 212 (RAM, Random Access Memory). It may also include a non-volatile memory 212 (NVM, NonVolatile Memory).

[0165] For example, at least one disk memory 212. The memory 212 is used to store programs.

[0166] Refer to Figure 3 The indoor controller 21 includes a communication interface 214. The communication interface 214 is used to implement communication with related components.

[0167] The communication interface 214 of the indoor controller 21 is used to communicate with the indoor expansion valve 13 and the outdoor controller 21. The communication interface 214 of the outdoor controller 21 is used to communicate with the outdoor expansion valve 23 and the indoor controller 21.

[0168] The indoor controller 21 includes a processor 213. The processor 213 is used to execute the executable modules stored in the memory 212, such as computer programs, and the code of the computer program can be in the form of source code, object code, executable file or some other forms.

[0169] The indoor controller 21 includes a bus 211. The bus 211 is used to connect the communication interface 214 and the processor 213. The bus 211 can be an ISA bus 211, a PCI bus 211 or an EISA bus 211, etc.

[0170] The outdoor controller 21 of the outdoor unit 2 and the indoor controller 21 of each indoor unit 1 each include at least one software function module that can be stored in the memory 212 in the form of software or firmware.

[0171] In this application, after receiving the execution instruction, the processor 213 executes the program to implement Figure 7 , 9 , the differential pressure balance method of the multi-connected air conditioner 100 shown in 13.

[0172] In some embodiments of this application, the controller 21 is at least used to control the compressor 24, the indoor fan 11, the outdoor fan 26, the outdoor expansion valve 23, and the indoor expansion valve 13.

[0173] Figure 7 is a flowchart showing the differential pressure balance method of the suction port and the discharge port of the compressor 24 after the multi-connected air conditioner 100 is shut down according to some embodiments. The method is executed at the multi-connected air conditioner 100 having the indoor expansion valve 13 and the outdoor expansion valve 23.

[0174] In some embodiments, some operations of the above differential pressure balance method are optionally combined, and / or the order of some operations is optionally changed.

[0175] In some embodiments, referring to Figure 4 , when the multi-connected air conditioner 100 executes the heating mode before shutdown, after the multi-connected air conditioner 100 is shut down (S700), the indoor fan 11 is turned off to stop the indoor unit 1 from blowing air into the room continuously (S701).

[0176] The shutdown in this application refers to the complete shutdown of all the indoor units 1 in the indoor unit group 10. The shutdown instruction received by the controller 21 can be sent by user operation or a signal for the multi-connected air conditioner to stop when the set temperature is reached.

[0177] In some embodiments, referring to Figure 4 when the multi-connected air conditioner 100 executes the heating mode before shutting down, after the multi-connected air conditioner 100 shuts down, the outdoor fan 26 is turned off (S702).

[0178] In some embodiments, referring to Figure 5 all the indoor unit expansion valves 13 of all the indoor units 1 are opened to the second preset opening degree. As the shutdown time increases, the opening degree of the indoor unit expansion valve 13 decreases intermittently. After the working duration of the indoor unit expansion valve 13 since shutdown reaches the third preset duration t3, the opening degree of the indoor unit expansion valve 13 is adjusted to the maximum opening degree (S703).

[0179] In some embodiments, the second preset opening degree is less than the maximum opening degree. Here, the maximum opening degree is 100%, fully open.

[0180] The differential pressure balancing method in this application is applicable to the multi-connected air conditioner 100. After the controller 21 of the multi-connected air conditioner 100 receives the shutdown instruction, it controls the opening degree of the indoor unit expansion valve 13 in the multi-connected air conditioner 100 according to the operating state of the multi-connected air conditioner 100 before receiving the shutdown instruction, so as to accelerate the differential pressure balancing speed of the multi-connected air conditioner 100.

[0181] When adjusting the differential pressure between the suction port and the discharge port of the compressor 24 in this application, regardless of whether the indoor unit 1 was in a working state in the previous time, the indoor unit expansion valves 13 corresponding to all the indoor units 1 are adjusted in opening degree, so as to accelerate the flow of the refrigerant and accelerate the differential pressure balancing speed.

[0182] By balancing the differential pressure between the suction port and the discharge port of the compressor 24, it is prevented that after the multi-connected air conditioner 100 shuts down and the compressor 24 starts again, due to the large differential pressure between the suction port and the discharge port, the compressor 24 fails to start, affecting the operation and reliability of the air conditioning system.

[0183] During the adjustment process of the indoor unit expansion valve 13, first the indoor unit expansion valve 13 is adjusted to the second preset opening degree, and then the opening degree is reduced by an indefinite amount at an indefinite time interval until the shutdown duration reaches t3, and then the opening degree of the indoor unit expansion valve 13 is adjusted to the maximum opening degree.

[0184] During the time period of t3, the number of times the indoor unit expansion valve 13 is reduced can be Figure 5 the 4 times shown in Figure 8 It can also be the 3 times shown in

[0185] The number of adjustment times of the indoor unit expansion valve 13 can be changed according to factors such as the step setting of the expansion valve and the preset time for differential pressure balancing.

[0186] The technical solution protected in this embodiment is a technical solution in which, after the heating mode is executed, the multi-connected air conditioner 100 is turned off, and all the indoor unit expansion valves 13 are first at a set opening degree, then intermittently reduced, and finally maintained at the position of the maximum opening degree.

[0187] In some embodiments, referring to Figure 6 , when the multi-connected air conditioner 100 executes the heating mode and after shutdown, after the outdoor unit expansion valve 23 is closed for the first preset duration t1, the opening degree of the outdoor unit expansion valve 23 is adjusted to the first preset opening degree, and the outdoor unit expansion valve 23 works at the first preset opening degree for the second preset duration t2 and then is closed (S704).

[0188] The outdoor unit expansion valve 23 is first closed for a period of time to reduce the refrigerant flow rate. To prevent the gaseous refrigerant from impacting the indoor unit 1 when the indoor unit expansion valve 13 opens, generating noise and affecting the user experience.

[0189] The differential pressure balance method in this application is applicable to the multi-connected air conditioner 100. After the controller 21 of the multi-connected air conditioner 100 receives a shutdown instruction, it controls the opening degree of the outdoor unit expansion valve 23 in the multi-connected air conditioner 100 according to the operating state of the multi-connected air conditioner 100 before receiving the shutdown instruction, so as to accelerate the differential pressure balance speed of the multi-connected air conditioner 100.

[0190] It should be understood that the specific order of describing the operations of Figure 7 is only exemplary and is not intended to indicate that this order is the only order in which these operations can be executed. Those of ordinary skill in the art will think of various ways to reorder the operations described herein. For example, any one of S701, S702, S703, and S704 in the differential pressure balance method described in the above reference method can be changed.

[0191] In the above technical solution, there is no need to set an additional bypass pipeline between the exhaust pipeline and the return pipeline of the compressor 24, which can effectively simplify the pipeline structure of the multi-connected air conditioner 100. Furthermore, the production efficiency of the multi-connected air conditioner 100 can be improved, and the production cost of the multi-connected air conditioner 100 can be reduced. At the same time, the probability of pipeline damage can also be reduced, and the probability of the multi-connected air conditioner 100 malfunctioning during operation can be reduced.

[0192] It should be noted that the exhaust pipeline refers to the pipeline at the exhaust port position of the compressor 24. The return pipeline refers to the pipeline at the suction port position of the compressor 24.

[0193] In addition, it should be noted that the adjustment scheme of the indoor unit expansion valve 13 after the heating mode in this application can be any one of S703 and S903.

[0194] In some embodiments of this application, referring to Figure 8, when the multi-connected air conditioner 100 executes the heating mode before shutting down, after the multi-connected air conditioner 100 shuts down (S900), the opening degree of the indoor unit expansion valve 13 of all indoor units 1 is adjusted to the second preset opening degree. After working for the fourth preset duration t4, the opening degree of the indoor unit expansion valve 13 is adjusted to the third preset opening degree, and then it continues to decrease intermittently at a preset time interval until the working duration of the indoor unit expansion valve 13 after shutdown reaches the third preset duration t3, and then the opening degree of the indoor unit expansion valve 13 is adjusted to the maximum opening degree (S903).

[0195] In some embodiments, the third preset opening degree is less than the second preset opening degree.

[0196] Refer to Figure 8 to illustrate the change in the opening degree of the indoor unit expansion valve 13 after the multi-connected air conditioner 100 shuts down in one of the embodiments when the multi-connected air conditioner 100 executes the heating mode.

[0197] After the multi-connected air conditioner shuts down, first, the indoor unit expansion valve 13 is adjusted to the second preset opening degree and works at this opening degree for a time t4. Then, the opening degree of the indoor unit expansion valve 13 is adjusted down to the third preset opening degree and works at this opening degree for a duration of t6 - t4. Again, the opening degree of the indoor unit expansion valve 13 is adjusted down to the eighth preset opening degree and works at this opening degree for a duration of t3 - t6, and then the opening degree of the indoor unit expansion valve 13 is adjusted to the maximum opening degree.

[0198] In some embodiments, refer to Figure 5 , after the outdoor unit expansion valve 23 closes for the first preset duration t1, the opening degree of the outdoor unit expansion valve 23 is adjusted to the first preset opening degree. The outdoor unit expansion valve 23 works at the first preset opening degree and closes the outdoor unit expansion valve 23 after the shutdown time reaches the second preset duration t2 (S904).

[0199] In some embodiments, t4 = t2. That is, the time for the secondary closing of the outdoor unit expansion valve 23 after the multi-connected air conditioner 100 shuts down is the same as the working time of the indoor unit expansion valve 13 at the initially set opening degree in the multi-connected air conditioner 100.

[0200] First, the outdoor unit expansion valve 23 closes initially to reduce the refrigerant flow rate in the air conditioning system and prevent the gaseous refrigerant from impacting the indoor unit 1 when the indoor unit expansion valve 13 opens, causing noise.

[0201] After a period of time t1, the outdoor unit expansion valve 23 is opened to cooperate with the indoor unit expansion valve 13 for continuous pressure equalization.

[0202] When the time of the outdoor unit expansion valve 23 reaches t2, the outdoor unit expansion valve 23 is closed and the opening degree of the indoor unit expansion valve 13 is adjusted down. At this time, the indoor unit expansion valve 13 is used to continue pressure equalization.

[0203] In some embodiments, refer toFigure 4 When the multi-connected air conditioner 100 operates in the heating mode before shutting down, after the multi-connected air conditioner 100 shuts down (S900), the indoor fan 11 is turned off to stop the indoor unit 1 from continuing to blow air into the room (S901).

[0204] In some embodiments, referring to Figure 4 When the multi-connected air conditioner 100 operates in the heating mode before shutting down, after the multi-connected air conditioner 100 shuts down, the outdoor fan 26 is turned off (S902).

[0205] It should be understood that the specific order described for the Figure 9 operations is merely exemplary and is not intended to indicate that the order is the only order in which these operations can be performed. Those of ordinary skill in the art will think of various ways to reorder the operations described herein. For example, S901, S902, S903, and S904 in the differential pressure balance method described in the above reference method can be changed arbitrarily.

[0206] In this application, since the indoor unit expansion valve 13 of the unpowered indoor unit 1 is used for pressure equalization, it is particularly important to reduce the noise generation during the pressure equalization process in this application and reduce the impact on users of unused air conditioners.

[0207] During the heating operation of the multi-connected unit, the opening of the outdoor unit expansion valve 23 is small. To ensure full balance of the high and low pressure differentials and at the same time take into account the refrigerant return. In the related art, when the multi-connected air conditioner 100 shuts down in the heating mode. The control of the outdoor unit expansion valve 23 increases the current opening, that is, the opening of the outdoor unit expansion valve 23 during the delayed closing process is larger than the opening of the outdoor unit expansion valve 23 when the compressor 24 stops.

[0208] However, this technical solution in the related art will cause the gaseous refrigerant in the indoor unit 1 to impact the indoor unit 1, resulting in a whistling sound and affecting the user experience.

[0209] In the technical solution of this embodiment, first, the opening of the outdoor unit expansion valve 23 is closed, and by reducing the amount of refrigerant in the pipeline, the impact of the gaseous refrigerant on the indoor unit 1 is reduced to solve the noise problem of the indoor unit 1 during the pressure equalization process.

[0210] In some embodiments of this application, referring to Figure 10 When the multi-connected air conditioner 100 operates in the cooling mode, after shutting down (S1300), the indoor fan 11 stops rotating to stop the indoor unit 1 from continuing to blow air into the room (S1301).

[0211] In some embodiments, when the multi-connected air conditioner 100 operates in the cooling mode, referring to Figure 10 After shutting down, the outdoor fan 26 stops rotating (S1302).

[0212] In some embodiments, when the multi-connected air conditioner 100 executes the cooling mode, after shutdown, referring to Figure 11 , the outdoor expansion valve 23 always remains at the maximum opening (S1303).

[0213] In some embodiments, when the multi-connected air conditioner 100 executes the cooling mode, after shutdown, referring to Figure 12 , the indoor expansion valve 13 is adjusted to the fourth preset opening. As the shutdown time increases, the opening of the indoor expansion valve 13 is intermittently reduced until the opening of the indoor expansion valve 13 is reduced to the fifth preset opening and stops decreasing and remains at the fifth preset opening (S1304).

[0214] In some embodiments, the fourth preset opening is less than the maximum opening, and the fifth preset opening is greater than 0%.

[0215] Referring to Figure 12 , it illustrates the opening change of the indoor expansion valve 13 in one of the embodiments when the multi-connected air conditioner 100 executes the cooling mode and after the multi-connection is shut down.

[0216] After the multi-connection is shut down, first, the indoor expansion valve 13 is adjusted to the fourth preset opening and operates at this opening size for a time t10. Then, the opening of the indoor expansion valve 13 is adjusted to the eleventh preset opening and operates at this opening size for a duration of t11 - t10. Once again, the opening of the indoor expansion valve 13 is adjusted to the twelfth preset opening and operates at this opening size for a duration of t12 - t11, and then the opening of the indoor expansion valve 13 is adjusted to the fifth preset opening and remains at this opening.

[0217] After the multi-connected air conditioner 100 executes the cooling mode and shuts down, the indoor expansion valve 13 is adjusted to the fourth preset opening. This fourth preset opening should not be too large to reduce the generation of refrigerant flow noise and avoid excessive noise during the pressure equalization process, which affects the user experience.

[0218] It should be noted that when the multi-connected air conditioner 100 executes the cooling mode, the refrigerant flowing in the indoor heat exchanger 12 is liquid refrigerant. When the multi-connection executes the heating mode, the refrigerant flowing in the indoor heat exchanger 12 is gaseous refrigerant. Therefore, the opening of the indoor expansion valve 13 after shutting down in the cooling mode is smaller than the opening of the indoor expansion valve 13 after shutting down in the heating mode.

[0219] In the heating mode, the refrigerant regulated by the indoor expansion valve 13 is in a gaseous state and is not likely to generate refrigerant flow noise. Implementing a larger expansion valve opening can achieve pressure difference balance as soon as possible.

[0220] In some embodiments, the fourth preset opening is less than the second preset opening to reduce the flow noise of the liquid refrigerant in the cooling mode.

[0221] It should be understood that forFigure 13 The specific order described for the operations is merely exemplary and is not intended to indicate that the order is the only order in which these operations can be performed. Those of ordinary skill in the art will think of various ways to reorder the operations described herein. For example, any one of S1301, S1302, S1303, and S1304 in the differential pressure balancing method described in the above reference method can be changed.

[0222] In addition, it should be noted that the details of other processes described herein with respect to other methods also apply to the differential pressure balancing method described above in a similar manner. Figure 13 to the differential pressure balancing method described above.

[0223] In this application, since the indoor unit expansion valve 13 of the unpowered indoor unit 1 is used for pressure equalization, it is particularly important to reduce the noise generation during the pressure equalization process in this application and reduce the impact on users of unused air conditioners.

[0224] When the multi-connected unit operates in the cooling mode, the opening of the outdoor unit expansion valve 23 is the maximum opening. To ensure full balance of the high and low pressure differentials and at the same time take into account refrigerant return. In the related art, when the multi-connected air conditioner 100 shuts down in the heating mode. The expansion valve of the indoor unit 1 in the on state is controlled to maintain the opening and continue to operate to ensure full balance of the pressure differential after shutdown.

[0225] However, the pressure equalization speed in the above technical solutions is slow, and the multi-connected air conditioner 100 cannot be quickly restored to a state where it can be turned on again. In this embodiment, the indoor unit expansion valves 13 of all the indoor units 1 are used to adjust the pressure differential. At the same time, in order to avoid generating noise and affecting the user experience, all the indoor unit expansion valves 13 are adjusted to a set opening size after shutdown to avoid the refrigerant flow sound caused by the over-large opening of the indoor unit expansion valve 13.

[0226] In some embodiments, when shutting down the multi-connected air conditioner 100 in the cooling mode, the corresponding indoor unit 1 is first shut down, and then the outdoor unit 2 is shut down.

[0227] In some embodiments, when the indoor unit 1 is shut down and the outdoor unit 2 is turned on, the indoor fan 11 remains in the operating state. So that the indoor fan 11 blows the residual heat or cold in the indoor unit 1 into the room.

[0228] In some embodiments, when the indoor unit 1 is shut down and the outdoor unit 2 is turned on, the outdoor fan 26 remains in the operating state. To use the outdoor fan 26 to blow the residual heat or cold in the outdoor unit 2 to the outside.

[0229] In some embodiments, when the outdoor unit 2 is turned off, the indoor fan 11 stops rotating to stop the indoor unit 1 from blowing air into the room continuously, thus avoiding the indoor unit 1 from blowing out air that has not been effectively heat-exchanged by the indoor heat exchanger 12, which may lead to the blown air not meeting the user's requirements and affecting the user experience.

[0230] In some embodiments, when the outdoor unit 2 is turned off, the outdoor fan 26 stops rotating, which can inform the user that the multi-connected air conditioner 100 has received the shutdown signal and will not give a false impression that may cause the user to misunderstand that the air conditioner is not turned off.

[0231] In some embodiments of the present application, the multi-connected air conditioner 100 includes a first pressure detection device disposed at the suction port of the compressor 24 for detecting a first pressure value at the suction port of the compressor 24.

[0232] The first pressure detection device is set as a pressure sensor for detecting the first pressure value at the suction port of the compressor 24.

[0233] In some embodiments of the present application, the multi-connected air conditioner 100 includes a second pressure detection device disposed at the discharge port of the compressor 24 for detecting a second pressure value at the discharge port of the compressor 24.

[0234] The second pressure detection device is set as a pressure sensor for detecting the second pressure value at the discharge port of the compressor 24.

[0235] In some embodiments, after the multi-connected air conditioner 100 is turned off, a first pressure value and a second pressure value are obtained, and a pressure difference is calculated. The pressure difference is the absolute value of the difference between the first pressure value and the second pressure value. When the pressure difference exceeds a preset pressure difference, a pressure equalization operation is performed.

[0236] That is, when the pressure difference exceeds the preset pressure difference, the opening degrees of the indoor expansion valve 13 and the outdoor expansion valve 23 are adjusted to balance the discharge port and the suction port of the compressor 24.

[0237] The pressure equalization operation refers to the adjustment operations for the indoor expansion valve 13, the outdoor expansion valve 23, the indoor fan 11, and the outdoor fan 26 after the above-mentioned shutdown.

[0238] It should be noted that the above-mentioned preset pressure difference refers to the pressure difference between the suction port and the discharge port of the compressor 24 when the compressor 24 cannot operate normally due to the pressure difference.

[0239] In some embodiments of the present application, when the pressure difference does not exceed the preset pressure difference, the pressure equalization operation is not performed.

[0240] In some embodiments of the present application, when the multi-connected air conditioner 100 executes the heating mode before shutdown, after shutdown, the indoor fan 11 is turned off to stop the indoor unit 1 from blowing air into the room continuously.

[0241] In some embodiments, the heating mode is executed before the multi-connected air conditioner 100 is shut down. After shutdown, the outdoor fan 26 is turned off.

[0242] In some embodiments, the heating mode is executed before the multi-connected air conditioner 100 is shut down. Refer to Figure 15 , after shutdown, the outdoor expansion valve 23 is adjusted to the sixth preset opening degree, and the outdoor expansion valve 23 is closed after working for a period of time.

[0243] In some embodiments, refer to Figure 14 , before the multi-connected air conditioner 100 is shut down, the heating mode is executed. After shutdown, the indoor expansion valves 13 of all the indoor units 1 are all opened to the seventh preset opening degree. As the shutdown time increases, the opening degree of the indoor expansion valve 13 decreases intermittently. After the working duration of the indoor expansion valve 13 since shutdown reaches the fifth preset duration t5, the opening degree of the indoor expansion valve 13 is adjusted to the maximum opening degree X. Among them, the seventh preset opening degree is less than the maximum opening degree.

[0244] Refer to Figure 14 , to illustrate the change in the opening degree of the indoor expansion valve 13 in one of the embodiments when the multi-connected air conditioner 100 executes the heating mode and after the multi-connected air conditioner is shut down.

[0245] After the multi-connected air conditioner is shut down, first, the indoor expansion valve 13 is adjusted to the seventh preset opening degree and works at this opening degree for a time t8. Then, the opening degree of the indoor expansion valve 13 is adjusted down to the ninth preset opening degree and works at this opening degree for a duration of t9 - t8. Again, the opening degree of the indoor expansion valve 13 is adjusted down to the tenth preset opening degree and works at this opening degree for a duration of t5 - t9, and then the opening degree of the indoor expansion valve 13 is adjusted to the maximum opening degree.

[0246] In some embodiments, when shutting down the multi-connected air conditioner 100 after executing the heating mode, the corresponding indoor unit 1 is first turned off, and then the outdoor unit 2 is turned off.

[0247] In some embodiments, when the indoor unit 1 is turned off and the outdoor unit 2 is turned on, the indoor fan 11 remains in the working state. So that the indoor fan 11 blows the residual heat or cold in the indoor unit 1 into the room.

[0248] In some embodiments, when the indoor unit 1 is turned off and the outdoor unit 2 is turned on, the outdoor fan 26 remains in the working state. To use the outdoor fan 26 to blow the residual heat or cold in the outdoor unit 2 to the outside.

[0249] In some embodiments, when the outdoor unit 2 is turned off, the indoor fan 11 stops rotating to stop the indoor unit 1 from blowing air into the room continuously, avoiding blowing out airflows that have not been effectively heat-exchanged by the indoor heat exchanger 12, which may lead to the blown air not meeting the user's requirements and affecting the user experience.

[0250] In some embodiments, when the outdoor unit 2 is turned off, the outdoor fan 26 stops rotating, which can inform the user that the multi-connected air conditioner 100 has received the shutdown signal and will not give a false impression that may cause the user to misunderstand that the air conditioner is not turned off.

[0251] In some embodiments of the present application, a preset time for completing the pressure difference balance is set. The opening degrees and the working durations of different opening degrees of the indoor expansion valve 13 and the outdoor expansion valve 23 can be adjusted according to the obtained pressure difference between the suction port and the discharge port of the compressor 24 and the preset time.

[0252] In the embodiments of the present application, the expansion valve is set as the indoor expansion valve 13 and the outdoor expansion valve 23. The indoor expansion valve 13 is arranged in the indoor unit 1, and the outdoor expansion valve 23 is arranged in the outdoor unit 2. By adjusting the opening degrees of the indoor expansion valve 13 and the outdoor expansion valve 23 after shutdown, the balance of the pressure difference between the suction port and the discharge port of the compressor 24 is achieved. At the same time, the indoor fan 11 and the outdoor fan 26 are turned off after shutdown. At this time, since the multi-connected air conditioner 100 has been turned off, the indoor heat exchanger 12 no longer generates heat continuously, avoiding blowing out airflows that have not been effectively heat-exchanged by the indoor heat exchanger 12, which may lead to the blown air not meeting the user's requirements and affecting the user experience. Stopping the outdoor fan 26 can inform the user that the multi-connected air conditioner 100 has received the shutdown signal and will not give a false impression that may cause the user to misunderstand that the air conditioner is not turned off.

[0253] In the present application, regardless of the working state of the indoor unit 1 before shutdown, it participates in the pressure difference balance method after shutdown to achieve rapid pressure equalization. This solution can still quickly achieve pressure difference balance even when the pressure difference between the suction port and the discharge port of the compressor 24 is large.

[0254] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application and are not intended to limit them. Although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some or all of the technical features. However, such modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

[0255] For ease of explanation, the above description has been presented in connection with specific embodiments. However, the above exemplary discussion is not intended to be exhaustive or to limit the embodiments to the specific forms disclosed. Various modifications and variations are possible in light of the above teachings. The selection and description of the above embodiments were made to better explain the principles and practical applications, so that those skilled in the art can better use the embodiments and various different variations of the embodiments suitable for specific uses.

Claims

1. A multi-connected air conditioner, characterized in that, Comprising: An outdoor unit, which includes: An outdoor housing; A compressor having a suction port and a discharge port; An outdoor heat exchanger disposed in the outdoor housing for heat exchange with outdoor air; An outdoor fan that rotates to allow outdoor air to enter the outdoor housing, and the outdoor air flows out of the outdoor housing after heat exchange with the outdoor heat exchanger; An outdoor expansion valve connected to the outdoor heat exchanger for regulating the refrigerant flow rate in the air conditioning system; An indoor unit group, which includes a plurality of indoor units, and each indoor unit includes: An indoor housing; An indoor heat exchanger disposed in the indoor housing for heat exchange with indoor air; An indoor fan that rotates to allow indoor air to enter the indoor housing, and the indoor air flows out of the indoor housing after heat exchange with the indoor heat exchanger; An indoor expansion valve connected to the indoor heat exchanger for regulating the refrigerant flow rate in the air conditioning system; The multi-connected air conditioner further includes: A controller that is at least used to control the compressor, the indoor fan, the outdoor fan, the outdoor expansion valve, and the indoor expansion valve; The controller is configured to: when the multi-connected air conditioner executes the heating mode before shutdown, after shutdown, the indoor fan is turned off to stop the indoor unit from continuing to blow air into the room; the outdoor fan is turned off; After the outdoor expansion valve is closed for a first preset duration t1, the opening degree of the outdoor expansion valve is adjusted to a first preset opening degree, and the outdoor expansion valve works at the first preset opening degree for a second preset duration t2 and then is closed; The opening degrees of the indoor expansion valves of all the indoor units are all opened to a second preset opening degree. As the shutdown time increases, the opening degree of the indoor expansion valve decreases intermittently. When the working duration of the indoor expansion valve after shutdown reaches a third preset duration t3, the opening degree of the indoor expansion valve is adjusted to the maximum opening degree; Wherein, the second preset opening degree is smaller than the maximum opening degree.

2. The multi-connected air conditioner according to claim 1, characterized in that, When the multi-connected air conditioner executes the heating mode and after shutdown, the controller is configured to: The opening degrees of the indoor expansion valves of all the indoor units are adjusted to the second preset opening degree. After working for a fourth preset duration t4, the opening degrees of the indoor expansion valves are adjusted to a third preset opening degree, and then continue to decrease intermittently at a preset time interval until the working duration of the indoor expansion valve after shutdown reaches the third preset duration t3, and then the opening degrees of the indoor expansion valves are adjusted to the maximum opening degree; Wherein, the third preset opening degree is smaller than the second preset opening degree, and t4 = t2.

3. The multi-connected air conditioner according to claim 1 or 2, characterized in that, The controller is further configured to: When the multi-connected air conditioner executes the cooling mode and after shutdown, the indoor fan and the outdoor fan stop rotating to stop the indoor unit from continuing to blow air into the room; The outdoor expansion valve always maintains the maximum opening degree; the indoor expansion valve is adjusted to a fourth preset opening degree. As the shutdown time increases, the opening degree of the indoor expansion valve decreases intermittently until the opening degree of the indoor expansion valve decreases to a fifth preset opening degree and stops decreasing further and remains at this opening degree; Wherein, the fourth preset opening degree is smaller than the maximum opening degree, and the fifth preset opening degree is greater than 0%.

4. The multi-connected air conditioner according to claim 3, characterized in that, The fourth preset opening degree is smaller than the second preset opening degree to reduce the flow sound of the liquid refrigerant in the cooling mode.

5. The multi-connected air conditioner according to claim 1 or 2, characterized in that, The controller is configured to: when shutting down the multi-connected air conditioner, first shut down the corresponding indoor unit, and then shut down the outdoor unit; When the indoor unit is shut down and the outdoor unit is turned on, the indoor fan and the outdoor fan remain in the working state; When the outdoor unit is shut down, the indoor fan and the outdoor fan stop rotating.

6. The multi-connected air conditioner according to claim 1 or 2, characterized in that, It further includes: A first pressure detection device, which is arranged at the suction port of the compressor and is used to detect the first pressure value at the suction port of the compressor; A second pressure detection device, which is arranged at the discharge port of the compressor and is used to detect the second pressure value at the discharge port of the compressor; The controller is further configured to: after the multi-connected air conditioner is shut down, obtain a pressure difference, where the pressure difference is the absolute value of the difference between the first pressure value and the second pressure value, and when the pressure difference exceeds a preset pressure difference, perform a pressure equalization operation.

7. The multi-connected air conditioner according to claim 6, wherein The controller is further configured to: when the pressure difference does not exceed the preset pressure difference, do not perform a pressure equalization operation.

8. A multi-connected air conditioner, characterized in that, It includes: An outdoor unit, which includes: An outdoor housing; A compressor, which has a suction port and a discharge port; An outdoor heat exchanger, which is arranged in the outdoor housing and is used to exchange heat with outdoor air; An outdoor fan, which rotates to allow outdoor air to enter the outdoor housing, and the outdoor air flows out of the outdoor housing after exchanging heat with the outdoor heat exchanger; An outdoor expansion valve, which is communicated with the outdoor heat exchanger and is used to adjust the refrigerant flow rate in the air conditioning system; An indoor unit group, which includes a plurality of indoor units, and the indoor unit includes: An indoor housing; An indoor heat exchanger, which is arranged in the indoor housing and is used to exchange heat with indoor air; An indoor fan, which rotates to allow indoor air to enter the indoor housing, and the indoor air flows out of the indoor housing after exchanging heat with the indoor heat exchanger; An indoor expansion valve, which is communicated with the indoor heat exchanger and is used to adjust the refrigerant flow rate in the air conditioning system; The multi-connected air conditioner further includes: A controller, which is at least used to control the compressor, the indoor fan, the outdoor fan, the outdoor expansion valve, and the indoor expansion valve; The controller is configured to: when the multi-connected air conditioner executes the heating mode before shutting down, after shutting down, the indoor fan is turned off to stop the indoor unit from continuing to blow air into the room; the outdoor fan is turned off; The outdoor expansion valve is adjusted to the sixth preset opening degree, and after working for a period of time, the outdoor expansion valve is closed; The indoor expansion valves of all the indoor units are all opened to the seventh preset opening degree. As the shutdown time increases, the opening degree of the indoor expansion valve decreases intermittently. After the working duration of the indoor expansion valve reaches the fifth preset duration t5 after shutdown, the opening degree of the indoor expansion valve is adjusted to the maximum opening degree; Wherein, the seventh preset opening degree is less than the maximum opening degree.

9. The multi-connected air conditioner according to claim 8, characterized in that, The controller is configured to: when shutting down the multi-connected air conditioner, first shut down the corresponding indoor unit, and then shut down the outdoor unit; When the indoor unit is shut down and the outdoor unit is turned on, the indoor fan and the outdoor fan remain in the working state; When the outdoor unit is shut down, the indoor fan and the outdoor fan stop rotating.

10. A multi-connected air conditioner, characterized in that An outdoor unit, which includes: An outdoor housing; A compressor having a suction port and a discharge port; An outdoor heat exchanger disposed in the outdoor housing for exchanging heat with outdoor air; An outdoor fan that rotates to allow outdoor air to enter the outdoor housing, and the outdoor air flows out of the outdoor housing after exchanging heat with the outdoor heat exchanger; An outdoor expansion valve connected to the outdoor heat exchanger for regulating the refrigerant flow rate in the air conditioning system; An indoor unit including a plurality of indoor machines, and each indoor machine includes: An indoor housing; An indoor heat exchanger disposed in the indoor housing for exchanging heat with indoor air; An indoor fan that rotates to allow indoor air to enter the indoor housing, and the indoor air flows out of the indoor housing after exchanging heat with the indoor heat exchanger; An indoor expansion valve connected to the indoor heat exchanger for regulating the refrigerant flow rate in the air conditioning system; The multi-connected air conditioner further includes: A controller at least for controlling the compressor, the indoor fan, the outdoor fan, the outdoor expansion valve, and the indoor expansion valve; The controller is configured such that when the multi-connected air conditioner executes a cooling mode before shutdown, after shutdown, the indoor fan and the outdoor fan stop rotating to stop the indoor machine from continuing to blow air into the room; The outdoor expansion valve always maintains the maximum opening; the indoor expansion valve is adjusted to a fourth preset opening, and as the shutdown time increases, the opening of the indoor expansion valve is intermittently reduced until the opening of the indoor expansion valve is reduced to a fifth preset opening and stops decreasing further and remains at this opening; Wherein, the fourth preset opening is less than the maximum opening, and the fifth preset opening is greater than 0%.

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