Multi-split air conditioner

Abstract

This application discloses a multi-split air conditioner, including at least two indoor units and an outdoor unit, each equipped with an indoor unit expansion valve. The outdoor unit includes a compressor, an outdoor unit expansion valve, an exhaust temperature detection device, and an exhaust pressure detection device. When the temperature control stops, upon receiving a first signal, the outdoor unit expansion valve remains closed, while the indoor unit expansion valves of both the shut-off and start-up indoor units open to achieve system pressure equalization. When the operating parameters of the multi-split air conditioner reach the start-up / shutdown conditions, the indoor unit expansion valves of both the shut-off and start-up indoor units remain open to allow refrigerant from the shut-off indoor unit to flow into the outdoor unit, based on a preset initial valve opening degree and opening... The first logical operation on the degree parameter yields the target opening degree of the outdoor unit expansion valve, in order to reduce the exhaust temperature or exhaust pressure. The opening degree parameter is obtained based on the first logical judgment of the first difference between the exhaust temperature at the previous temperature control shutdown and the exhaust temperature after the current startup. The larger the first difference, the larger the opening degree parameter. By considering the temperature change trend between the exhaust temperature before temperature control shutdown and the exhaust temperature at temperature control startup, the initial valve opening degree of the outdoor unit expansion valve for this temperature control startup is specified to prevent problems such as excessively high exhaust temperature and low outlet air temperature caused by insufficient refrigerant circulation during partial load operation.

Description

Technical Field

[0001] This invention belongs to the field of air conditioner technology, and particularly relates to a multi-split air conditioner. Background Technology

[0002] A multi-split air conditioner can connect one outdoor unit to multiple indoor units. It can operate with one indoor unit running at a time, or multiple indoor units can operate simultaneously. The control system of a multi-split air conditioner reads the actual temperature and set temperature data of the indoor air-conditioned room and controls the operating status of the indoor and outdoor units.

[0003] Currently, multi-split air conditioners often experience frequent temperature-controlled on / off cycles of the indoor unit when the outdoor ambient temperature is high during heating mode. Furthermore, when the indoor unit is off during heating, the electronic expansion valve maintains a fixed opening. When the indoor unit is on again, refrigerant can easily remain inside. If the number of temperature-controlled on / off cycles accumulates to a certain level, it can lead to insufficient refrigerant circulation in the air conditioning system, resulting in higher exhaust temperatures and even triggering alarms and system shutdowns.

[0004] In related technologies, it is first determined whether the exhaust superheat meets the set range. If it does, the opening of the electronic expansion valve is adjusted using the intake superheat. If the exhaust superheat does not meet the set conditions, the opening of the electronic expansion valve is adjusted using the exhaust superheat.

[0005] In view of the above, this application is hereby submitted. Summary of the Invention

[0006] This application considers the temperature change trend between the exhaust temperature before temperature-controlled shutdown and the exhaust temperature when temperature-controlled startup, and specifies the initial valve opening of the outdoor unit expansion valve for this temperature-controlled startup to prevent problems such as excessively high exhaust temperature and low outlet air temperature caused by insufficient refrigerant circulation during partial load operation.

[0007] This application embodiment proposes a multi-split air conditioner, which includes:

[0008] An indoor unit includes at least two indoor units. During operation, the indoor unit in the off state is defined as the off indoor unit, and the indoor unit in the on state is defined as the on indoor unit. The indoor units include:

[0009] The indoor unit's expansion valve is used to regulate the refrigerant.

[0010] Outdoor unit, the outdoor unit includes:

[0011] A compressor, which has an intake port and an exhaust port;

[0012] The outdoor unit's expansion valve is used to regulate the refrigerant.

[0013] An exhaust temperature detection device is installed at the exhaust port to detect the exhaust temperature;

[0014] An exhaust pressure detection device, located at the exhaust port, is used to detect exhaust pressure;

[0015] The controller is configured such that after temperature-controlled shutdown, upon receiving the first signal, the outdoor unit expansion valve remains closed, while the indoor unit expansion valves open for both shutdown and startup of the indoor unit, so as to allow the liquid refrigerant on the outdoor side to evaporate.

[0016] When the operating parameters of the multi-split air conditioner reach the start-up and shutdown conditions, the expansion valves of the indoor units of both the off and on indoor units remain open to allow the refrigerant in the off indoor unit to flow into the outdoor unit. Based on the preset initial valve opening degree and opening parameters, the first logic operation is performed to obtain the target opening degree of the outdoor unit expansion valve in order to reduce the exhaust temperature or exhaust pressure.

[0017] The opening parameter is obtained based on the first logic judgment of the first difference between the exhaust temperature when the previous temperature control shutdown and the exhaust temperature after the current startup. The larger the first difference, the larger the opening parameter.

[0018] After working for a period of time, the indoor unit expansion valve of the shut-off indoor unit closes to the preset shutdown opening, and the indoor unit expansion valve of the start-up indoor unit adjusts according to the subcooling degree.

[0019] In some embodiments, the multi-split air conditioner further includes:

[0020] An inhalation pressure detection device, located at the inhalation port, is used to detect inhalation pressure;

[0021] The controller is configured to determine whether the start-up and shutdown conditions are met when the operating parameters of the multi-split air conditioner meet at least one of the following conditions;

[0022] (1) The compressor has run for the preset time;

[0023] (2) The exhaust pressure reaches the first preset exhaust pressure;

[0024] (3) The inhalation pressure reaches the preset inhalation pressure;

[0025] (4) The exhaust temperature reaches the first preset exhaust temperature.

[0026] In some embodiments, in the first logical operation, the opening parameter is related to the trend of exhaust temperature change and the current exhaust temperature;

[0027] The difference between the current exhaust temperature and the previous exhaust temperature is defined as the first difference, and the difference between the previous exhaust temperature and the previous two exhaust temperatures is defined as the second difference.

[0028] When the difference between the second difference and the first difference exceeds the second preset difference and the exhaust temperature exceeds the second preset exhaust temperature, the opening parameter is taken as the second opening parameter.

[0029] When the exhaust temperature does not reach the second preset exhaust temperature, and the first difference does not reach the first preset difference, and the difference between the second difference and the first difference does not reach the second preset difference, the opening parameter is taken as the first opening parameter.

[0030] Among them, the first preset difference is greater than the second preset difference, and the second opening parameter is greater than the first opening parameter.

[0031] In some embodiments, the controller is configured to, during the operation of the air conditioning unit, obtain the opening degree of the outdoor unit expansion valve to be adjusted through a second logic operation based on the previous opening degree and adjustment coefficient of the outdoor unit expansion valve;

[0032] The opening of the outdoor unit's expansion valve is adjusted based on the adjustment cycle, which is related to one or a combination of exhaust temperature, exhaust superheat, and exhaust pressure.

[0033] In some embodiments, the controller is configured to set the adjustment period to a third period T3 when the exhaust temperature does not reach a third preset exhaust temperature but exceeds a preset minimum exhaust temperature.

[0034] When the exhaust temperature reaches the third preset exhaust temperature but does not exceed the fourth preset exhaust temperature, the adjustment cycle is the second cycle T2.

[0035] When the exhaust temperature exceeds the fourth preset exhaust temperature, the adjustment cycle becomes the first cycle T1.

[0036] The third preset exhaust temperature is less than the fourth preset exhaust temperature, and T1 < T2 < T3.

[0037] In some embodiments, the controller is configured to calculate exhaust superheat based on exhaust temperature and exhaust pressure during operation of the air conditioning unit;

[0038] When the exhaust superheat exceeds the first preset exhaust superheat Tdsh1 but does not reach the second preset exhaust superheat Tdsh2, the adjustment cycle is set to the third cycle T3.

[0039] When the exhaust superheat reaches the second preset exhaust temperature Tdsh2 and does not exceed the third preset exhaust superheat Tdsh3, the adjustment cycle is the second cycle T2.

[0040] When the exhaust temperature exceeds the third preset exhaust superheat Tdsh3, the adjustment cycle becomes the first cycle T1;

[0041] Where Tdsh1 < Tdsh2 < Tdsh3, T1 < T2 < T3.

[0042] In some embodiments, the controller is configured to adjust the cycle to T1 when the suction pressure does not reach the preset low pressure value and the exhaust superheat exceeds the second preset exhaust superheat Tdsh2 during the operation of the air conditioning unit.

[0043] When the intake pressure does not reach the preset low pressure value, and the exhaust superheat is the first preset exhaust superheat Tdsh1 but does not reach the second preset exhaust superheat Tdsh2, the adjustment cycle is T2.

[0044] Where Tdsh1 < Tdsh2.

[0045] In some embodiments, the controller is configured to set the adjustment cycle to a first cycle when the exhaust superheat does not reach a first preset exhaust superheat, and adjust the opening of the outdoor unit expansion valve based on the opening degree and opening coefficient of the outdoor unit expansion valve at each first cycle T1 interval to reduce the opening degree of the outdoor unit expansion valve.

[0046] In some embodiments, when the exhaust temperature does not reach the preset minimum exhaust temperature and continues for a period of time, the opening of the outdoor unit expansion valve is adjusted every first cycle T1 based on the opening degree and opening coefficient of the previous outdoor unit expansion valve to reduce the opening degree of the outdoor unit expansion valve.

[0047] This application discloses a multi-split air conditioner, including at least two indoor units and an outdoor unit, each equipped with an indoor unit expansion valve. The outdoor unit includes a compressor, an outdoor unit expansion valve, an exhaust temperature detection device, and an exhaust pressure detection device. When the temperature control stops, upon receiving a first signal, the outdoor unit expansion valve remains closed, while the expansion valves of both the shut-off and start-up indoor units open to allow the liquid refrigerant on the outdoor side to evaporate. When the operating parameters of the multi-split air conditioner reach the start-up / shutdown conditions, the indoor unit expansion valves of both the shut-off and start-up indoor units remain open to allow the refrigerant in the shut-off indoor unit to flow into the outdoor unit, based on a preset initial valve opening... The target opening degree of the outdoor unit expansion valve is obtained by performing a first logical operation on the degree and opening degree parameters to reduce the exhaust temperature or exhaust pressure. The opening degree parameter is obtained based on the first logical judgment of the first difference between the exhaust temperature when the temperature control was shut down and the exhaust temperature after the current start-up. The larger the first difference, the larger the opening degree parameter. By considering the temperature change trend between the exhaust temperature before the temperature control was shut down and the exhaust temperature when the temperature control was started, the initial valve opening degree of the outdoor unit expansion valve is specified for the current temperature control start-up to prevent the exhaust temperature from being too high and the outlet air temperature from being too low due to insufficient refrigerant circulation during partial load operation.

[0048] This application also proposes another type of multi-split air conditioner, including:

[0049] An indoor unit includes at least two indoor units. During operation, the indoor unit in the off state is defined as the off indoor unit, and the indoor unit in the on state is defined as the on indoor unit. The indoor units include:

[0050] The indoor unit's expansion valve is used to regulate the refrigerant.

[0051] Outdoor unit, the outdoor unit includes:

[0052] A compressor, which has an intake port and an exhaust port;

[0053] The outdoor unit's expansion valve is used to regulate the refrigerant.

[0054] An exhaust temperature detection device is installed at the exhaust port to detect the exhaust temperature;

[0055] An exhaust pressure detection device, located at the exhaust port, is used to detect exhaust pressure;

[0056] The controller is configured such that, upon receiving the first signal, the outdoor unit expansion valve remains closed, while the indoor unit expansion valves open for both the indoor unit when it is turned off and when it is turned on, so that the liquid refrigerant on the outdoor side can evaporate.

[0057] When the operating parameters of the multi-split air conditioner reach the start-up and shutdown conditions, the expansion valves of the indoor units of both the off and on indoor units remain open to allow the refrigerant in the off indoor unit to flow into the outdoor unit. The target opening of the outdoor unit expansion valve is obtained by performing a first logic operation based on the preset initial valve opening degree and opening degree parameters; wherein, the opening degree parameters are at least related to the exhaust pressure.

[0058] After working for a period of time, the indoor unit expansion valve of the shut-off indoor unit closes to the preset shutdown opening, and the indoor unit expansion valve of the start-up indoor unit adjusts according to the subcooling degree.

[0059] The initial valve opening of the outdoor unit's expansion valve is controlled based on the exhaust pressure to prevent problems such as excessively high exhaust temperature and low outlet air temperature caused by insufficient refrigerant circulation during partial load operation. Attached Figure Description

[0060] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this application, illustrate exemplary embodiments of the invention and, together with their description, serve to explain the invention and do not constitute an undue limitation thereof. In the drawings:

[0061] Figure 1 This is a structural block diagram of a multi-split air conditioner according to one embodiment of the present invention;

[0062] Figure 2 This is a system block diagram of an air conditioning system according to one embodiment of the present invention;

[0063] Figure 3 This is a hardware block diagram of the controller in one embodiment of the present invention;

[0064] Figure 4This is a hardware block diagram of a multi-split air conditioner according to one embodiment of the present invention;

[0065] Figure 5 This is the control logic of the outdoor unit expansion valve when restarting after a temperature-controlled shutdown in one embodiment of the present invention;

[0066] Figure 6 This is the selection and control logic for the opening parameter in one embodiment of the present invention;

[0067] Figure 7 This is the control logic for determining start-up and exit conditions in one embodiment of the present invention;

[0068] Figure 8 This is the control logic for the adjustment cycle of the electronic expansion valve in one embodiment of the present invention;

[0069] Figure 9 This is a control logic in one embodiment of the present invention for adjusting the opening of the outdoor unit expansion valve according to the exhaust temperature;

[0070] Figure 10 This is the control logic for the adjustment cycle of the outdoor unit expansion valve in one embodiment of the present invention;

[0071] Figure 11 This is the control logic of controlling the outdoor unit expansion valve based on exhaust superheat and exhaust pressure in one embodiment of the present invention;

[0072] In the above image:

[0073] Multi-split air conditioner: 100; Outdoor unit: 14; Indoor unit: 16;

[0074] Controller 21; Bus 211; Memory 212; Processor 213; Communication interface 214.

[0075] Compressor 1; Four-way valve 4; Discharge pressure detection device 71; Discharge temperature detection device 72;

[0076] 73; Intake pressure detection device; 5; Expansion valve of indoor unit; 6; Expansion valve of outdoor unit; 8; Outdoor heat exchanger;

[0077] Indoor heat exchanger 3. Detailed Implementation

[0078] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0079] In the description of this invention, it should be understood that the terms "center", "lateral", "longitudinal", "up", "down", "front", "back", "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 used only for the convenience of describing this invention 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 limiting this invention.

[0080] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" 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 direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0081] This application discloses a multi-split air conditioner 100, with reference to... Figure 1 The multi-split air conditioner 100 includes an indoor unit, which includes at least two indoor units 16.

[0082] The indoor unit comprises multiple indoor units 16. The multiple indoor units 16 are connected in parallel.

[0083] During the operation of the multi-split air conditioning unit 100, the indoor unit 16 may be in a power-off state or a power-on state due to unit load or user settings. The indoor unit 16 in the power-off state is defined as the power-off indoor unit, and the indoor unit 16 in the power-on state is defined as the power-on state.

[0084] The multi-split air conditioner 100 includes the outdoor unit.

[0085] The outdoor unit includes at least one outdoor unit 14. When two or more outdoor units 14 are installed, the outdoor units 14 are connected in parallel.

[0086] Outdoor unit 14 is installed outdoors. Indoor unit 16 and outdoor unit 14 are connected by pipes for refrigerant flow.

[0087] The indoor unit 16 includes an indoor housing. The indoor housing forms the outer contour of the indoor unit 16 and houses the internal components of the indoor unit 16.

[0088] The interior casing has an interior air inlet. The interior air inlet is used to allow indoor air to enter the interior casing.

[0089] The inner casing has an indoor air outlet. The indoor air outlet is used to exhaust air from the inner casing. Indoor air enters the inner casing through the indoor air inlet and is then blown out from the indoor air outlet.

[0090] The indoor unit 16 includes an indoor heat exchanger 3. The indoor heat exchanger 3 is installed inside the indoor casing. The indoor heat exchanger 3 is used to exchange heat with indoor air entering the indoor casing.

[0091] The indoor unit 16 includes an indoor fan. The indoor fan is installed inside the indoor casing. The indoor fan rotates to allow indoor air to enter the indoor casing. After exchanging heat with the indoor heat exchanger 3, the indoor air flows out of the indoor casing.

[0092] In this application, indoor unit 16 includes, but is not limited to, wall-mounted air conditioners, cabinet air conditioners, and ducted air conditioners.

[0093] The outdoor unit 14 includes an outdoor housing. The outdoor housing forms the outer outline of the outdoor unit 14 and houses the internal components of the outdoor unit 14.

[0094] The outdoor casing has an outdoor air inlet, which is used to allow outdoor air to enter the outdoor casing.

[0095] The outdoor casing has an outdoor air outlet, which is used to exhaust air from the outdoor casing. Outdoor air enters the outdoor casing through the outdoor air inlet and is then blown out from the outdoor air outlet.

[0096] The outdoor unit 14 includes an outdoor heat exchanger 8, which is installed inside the outdoor casing and is used to exchange heat with the outdoor air entering the outdoor casing.

[0097] The outdoor unit 14 includes an outdoor fan, which is installed inside the outdoor casing. The outdoor fan rotates to allow outdoor air to enter the outdoor casing. After exchanging heat with the outdoor heat exchanger 8, the outdoor air flows out of the outdoor casing.

[0098] Reference Figure 2 This describes the system configuration of the air conditioning system in this application.

[0099] The outdoor unit 14 includes a compressor 1. The compressor 1 can compress the gaseous refrigerant at high temperature and high pressure and discharge the compressed gaseous refrigerant.

[0100] Compressor 1 includes an intake port. Refrigerant flows into compressor 1 from the intake port to be compressed.

[0101] Compressor 1 includes an exhaust port. Refrigerant enters compressor 1 through the suction port, is compressed by compressor 1, and is discharged through the exhaust port.

[0102] The outdoor unit 14 also includes a gas-liquid separator 6. The gas-liquid separator 6 is installed at the suction port of the compressor 1. The gas-liquid separator 6 is used for gas-liquid separation.

[0103] The outdoor unit 14 also includes a four-way valve 4. The first port of the four-way valve 4 is connected to the discharge port of the compressor 1. The second port of the four-way valve 4 is connected to the suction port of the compressor 1. The third port of the four-way valve 4 is connected to the indoor unit 16. The fourth port of the four-way valve 4 is connected to the outdoor heat exchanger 8.

[0104] The outdoor unit 14 includes an outdoor unit expansion valve 6. The outdoor unit expansion valve 6 is located on the side of the outdoor heat exchanger 8 closest to the indoor heat exchanger 3. The outdoor unit expansion valve 6 is used to regulate the refrigerant. The outdoor unit expansion valve 6 can expand the high-temperature, high-pressure liquid refrigerant condensed in the condenser into a low-pressure liquid phase refrigerant.

[0105] The indoor unit 16 includes an indoor unit expansion valve 5. The indoor unit expansion valve 5 is located on the side of the indoor heat exchanger 3 closest to the outdoor heat exchanger 8. The indoor unit expansion valve 5 is used to regulate the refrigerant.

[0106] The indoor unit expansion valve 5 can expand the high-temperature, high-pressure liquid refrigerant condensed in the condenser into a low-pressure liquid refrigerant. It can be used to regulate the refrigerant flow entering the corresponding indoor unit 16.

[0107] Indoor heat exchanger 3 and outdoor heat exchanger 8 function as either condensers or evaporators. When indoor heat exchanger 3 functions as a condenser, the air conditioner acts as a heater in heating mode. When indoor heat exchanger 3 functions as an evaporator, the air conditioner acts as a cooler in cooling mode.

[0108] Multi-split air conditioners 100 use refrigerant flow to blow out air that is higher or lower than the indoor temperature, or the same as the indoor temperature, in order to adjust the temperature and humidity of the indoor environment; or they use the speed of the indoor fan to adjust the airflow speed of the indoor environment.

[0109] The following explains the cooling and heating modes of the multi-split air conditioner 100.

[0110] When the multi-split air conditioner 100 is in cooling mode, the refrigerant from compressor 1 is condensed by the outdoor heat exchanger 8. The condensed refrigerant then expands by the first electronic expansion valve 7. The expanded condensate evaporates by the indoor heat exchanger 3. The evaporated refrigerant then circulates back to compressor 1.

[0111] When the multi-split air conditioner 100 is in heating mode, the refrigerant from compressor 1 flows through indoor heat exchanger 3 and condenses. The condensed refrigerant then expands by flowing through the first electronic expansion valve 7. The expanded condensate evaporates through outdoor heat exchanger 8. The evaporated refrigerant then circulates back to compressor 1.

[0112] In some embodiments of this application, the multi-split air conditioner 100 includes a remote control. The user inputs commands to the controller 21 via the remote control to select the operating modes of the indoor unit 16 and the outdoor unit 14.

[0113] In some implementations, the operating modes of the multi-split air conditioner 100 vary depending on the model and user needs. In this application, cooling mode, heating mode and shutdown mode are selected for description.

[0114] In the cooling mode, the air flowing from the indoor unit 16 into the room is cold air. This cold air can be defined as airflow that is lower than the indoor air temperature.

[0115] In heating mode, the air flowing from the indoor unit 16 into the room is hot air. This hot air can be defined as airflow with a temperature higher than the indoor air temperature. The concepts of heating and cooling modes are common knowledge to those skilled in the art.

[0116] In the shutdown mode, the multi-split air conditioner 100 does not improve parameters such as indoor temperature, humidity, and airflow speed.

[0117] In some embodiments of this application, the multi-split air conditioner 100 includes a controller 21. The controller 21 is used to send instructions to the multi-split air conditioner 100 to control the working process of the multi-split air conditioner 100.

[0118] The controller 21 is used to coordinate the operation of the entire multi-split air conditioner 100. This includes receiving user commands, operating in various modes such as cooling mode, heating mode, fan mode, and shutdown mode, as well as uploading the operating status of the multi-split air conditioner 100 to the cloud.

[0119] The structures of controller 21 and outdoor controller 21 are roughly the same. The structure of controller 21 will be explained using controller 21 as an example.

[0120] The controller 21 includes a memory 212. The memory 212 may include high-speed random access memory (RAM) or non-volatile memory (NVM).

[0121] For example, at least one disk storage device 212. Storage device 212 is used to store programs.

[0122] Reference Figure 3 The controller 21 includes a communication interface 214. The communication interface 214 is used to communicate with related components.

[0123] The communication interface 214 of the controller 21 is used to communicate with the indoor unit expansion valve 5, the outdoor unit expansion valve 6, the compressor, the exhaust temperature detection device 72, the exhaust pressure detection device 71, and the intake pressure detection device 73.

[0124] The controller 21 includes a processor 213. The processor 213 is used to execute executable modules stored in the memory 212, such as computer programs. The code of the computer program can be in the form of source code, object code, executable file, or some of these forms.

[0125] The 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.

[0126] The outdoor controller 21 of the outdoor unit 14 and the controller 21 of each indoor unit 16 each include at least one software function module that can be stored in the memory 212 in the form of software or firmware.

[0127] In this application, after receiving an execution instruction, the processor 213 executes the program to implement... Figure 5-11 The control method of the outdoor unit expansion valve 6 shown.

[0128] In some embodiments of this application, the controller 21 is used to control at least the compressor 1, the outdoor unit expansion valve 6, and the indoor unit expansion valve 5.

[0129] In this application, the operation of indoor unit 16 and outdoor unit 14 is controlled by temperature, and some indoor units 16 are turned on and some are turned off as needed.

[0130] The indoor unit 16 is switched on and off using temperature control. When the indoor temperature reaches the preset shutdown temperature, it will shut down. When the temperature drops below the preset startup temperature, it will turn on again.

[0131] When a multi-split air conditioner (e.g., 100°C) has good heating capacity, the indoor temperature will quickly reach the preset temperature, and the compressor will shut off. However, if the indoor temperature retention is poor and the temperature drops rapidly, it will quickly fall back to the preset operating temperature, causing the compressor to restart. This frequent starting and stopping of the compressor prevents it from reaching a stable state, leading to refrigerant buildup, insufficient refrigerant circulation within the air conditioning system, excessively high exhaust temperature, and even alarms. In severe cases, it can damage the compressor.

[0132] Reference Figure 4 The multi-split air conditioner 100 includes an exhaust temperature detection device 72. The exhaust temperature detection device 72 is installed at the compressor's exhaust port and is used to detect the compressor's exhaust temperature.

[0133] The exhaust temperature detection device 72 is electrically connected to the controller 21. The exhaust temperature detection device 72 is used to detect the exhaust temperature and send the detected exhaust temperature to the controller 21.

[0134] The multi-split air conditioner 100 includes an exhaust pressure detection device 71. The exhaust pressure detection device 71 is installed on the exhaust port of the compressor and is used to detect the exhaust pressure of the compressor.

[0135] The exhaust pressure detection device 71 is electrically connected to the controller 21. The exhaust pressure detection device 71 is used to detect the exhaust pressure and send the detected exhaust pressure to the controller 21.

[0136] The multi-split air conditioner 100 includes a suction pressure detection device 73. The suction pressure detection device 73 is installed at the suction port of the compressor and is used to detect the suction pressure of the compressor.

[0137] The inhalation pressure detection device 73 is electrically connected to the controller 21. The inhalation pressure detection device 73 is used to detect the inhalation pressure and send the detected inhalation pressure to the controller 21.

[0138] Reference Figure 5 This explains the control logic of the outdoor unit expansion valve 6 when restarting after a temperature-controlled shutdown in this application.

[0139] In some embodiments, the controller 21 is configured to keep the outdoor unit expansion valve 6 closed after receiving a first signal following a temperature-controlled shutdown, so as to allow the liquid refrigerant on the outdoor side to evaporate (S501).

[0140] In some embodiments, the controller 21 is configured to open the indoor unit expansion valve 5 for both the shut-down and start-up indoor units upon receiving a first signal after the temperature-controlled shutdown (S502).

[0141] The execution order of S501 and S502 in the above can be adjusted.

[0142] In some embodiments, when the operating parameters of the multi-split air conditioner 100 reach the start-up and shutdown conditions, the expansion valve 5 of the indoor unit in both the off and on indoor units remains open (S503) so that the refrigerant in the off indoor unit flows into the outdoor unit 14, increasing the refrigerant circulation volume.

[0143] In this embodiment, by increasing the time that the indoor unit expansion valve 5 of the indoor unit 16 and the outdoor unit expansion valve 6 of the outdoor unit 14 are opened simultaneously, the refrigerant stored in the shut-off indoor unit is released, preventing the indoor unit from triggering an alarm due to insufficient refrigerant when turned on.

[0144] In some embodiments, when the operating parameters of the multi-split air conditioner 100 reach the start-up and exit conditions, a first logical operation is performed based on the preset initial valve opening degree and opening parameters to obtain the target opening degree of the outdoor unit expansion valve 6 (S504) in order to reduce the exhaust temperature or exhaust pressure.

[0145] In some embodiments, after operating for a period of time according to the obtained target opening degree, the indoor unit expansion valve 5 of the shut-off indoor unit closes to the preset shutdown opening degree, and the indoor unit expansion valve 5 of the start-up indoor unit is adjusted according to the subcooling degree (S505).

[0146] In some embodiments, the opening parameter is obtained based on a first logic judgment according to a first difference between the exhaust temperature at the previous temperature control shutdown and the exhaust temperature after the current startup, wherein the larger the first difference is, the larger the opening parameter is.

[0147] In some embodiments, the indoor unit EVIN (n = 1, 2, ... n, where n is the number of indoor units in operation) is controlled by PID based on the subcooling degree of the indoor unit 16 to ensure the stability of the air conditioning system.

[0148] In some embodiments, by recording several consecutive exhaust temperatures, different preset difference levels are set based on the changes in exhaust temperature difference, corresponding to different opening parameters, to achieve precise control of the outdoor unit expansion valve 6. This allows for better adjustment of the opening of the outdoor unit expansion valve 6 according to changes in exhaust temperature, ensuring stable operation of the unit.

[0149] In some embodiments, after the expansion valve 5 of the indoor unit is opened in both the off and on indoor units, when the compressor's running time reaches a preset time, it is determined that the start-up and exit conditions are met.

[0150] In some embodiments, after the indoor unit expansion valve 5 is opened in both the off and on indoor units, when the exhaust pressure reaches the first preset exhaust pressure, it is determined that the start-up and exit conditions are met.

[0151] In some embodiments, after the indoor unit expansion valve 5 is opened in both the off and on indoor units, when the suction pressure reaches below the preset suction pressure, it is determined that the start-up exit condition is met.

[0152] It should be noted that under normal operating conditions, the inhalation pressure will gradually decrease over a certain period of time.

[0153] In some embodiments, after the indoor unit expansion valve 5 is opened in both the indoor unit that is turned off and the indoor unit that is turned on, when the exhaust temperature reaches the first preset exhaust temperature Td1, it is determined that the start-up and exit conditions are met.

[0154] Reference Figure 7 This describes the control logic for determining start and exit conditions.

[0155] Obtain the compressor's operating time, discharge pressure, suction pressure, and discharge temperature (S701);

[0156] Determine whether the compressor's running time has reached the preset time (S702);

[0157] In step S702, if the target is achieved, then step S703 is executed, keeping the indoor unit expansion valve 5 of both the shut-off and powered-on indoor units open, so that the refrigerant in the shut-off indoor unit flows into the outdoor unit 14, and performing the first logic operation based on the preset initial valve opening degree and opening degree parameters to obtain the target opening degree of the outdoor unit expansion valve 6.

[0158] In step S702, if the target is not reached, then step S704 is executed to determine whether the exhaust pressure has reached the first preset exhaust pressure.

[0159] If the condition is met in step S704, then step S703 is executed.

[0160] If the target is not reached in step S704, then step S705 is executed to determine whether the inhalation pressure has reached below the preset inhalation pressure.

[0161] If the condition is met in step S705, then step S703 is executed.

[0162] In step S705, if the temperature is not reached, then step S706 is executed to determine whether the exhaust temperature has reached the first preset exhaust temperature Td1.

[0163] If the condition is met in step S706, then step S703 is executed.

[0164] If the condition is not met in step S706, then step S701 is executed.

[0165] In some embodiments, in the first logical operation, the opening parameter is related to the trend of exhaust temperature change and the current exhaust temperature.

[0166] In some embodiments, the difference between the current exhaust temperature and the previous exhaust temperature is defined as the first difference, and the difference between the previous exhaust temperature and the previous two exhaust temperatures is defined as the second difference.

[0167] When the difference between the second difference and the first difference exceeds the second preset difference and the exhaust temperature exceeds the second preset exhaust temperature, the opening parameter is taken as the second opening parameter.

[0168] When the exhaust temperature does not reach the second preset exhaust temperature, and the first difference does not reach the first preset difference, and the difference between the second difference and the first difference does not reach the second preset difference, the opening parameter is taken as the first opening parameter.

[0169] The first preset difference is greater than the second preset difference.

[0170] Reference Figure 6 This explains the selection and control logic for the opening parameter in this application.

[0171] Obtain the current exhaust temperature and the exhaust temperature at the last temperature control shutdown (S601);

[0172] Determine whether the exhaust temperature has reached the third preset exhaust temperature (S 602);

[0173] In step S602, if the third preset exhaust temperature is reached, then step S603 is executed, and the opening coefficient is taken as the second opening parameter.

[0174] In step S602, if the third preset exhaust temperature is not reached, then step S604 is executed to calculate the first difference between the current exhaust temperature and the previous exhaust temperature.

[0175] Determine whether the first difference reaches the first preset difference (S605);

[0176] In step S605, if the first difference reaches the first preset difference, then step S603 is executed;

[0177] In step S605, if the first difference does not reach the first preset difference, then step S606 is executed to obtain the exhaust temperature at the time of the first two temperature control shutdowns.

[0178] Calculate the second difference between the exhaust temperature of the previous two times and the exhaust temperature of the previous time (S607);

[0179] Determine whether the second difference reaches the second preset difference (S608);

[0180] In step S608, if the second difference reaches the second preset difference, then step S609 is executed to determine whether the exhaust temperature exceeds the second preset exhaust temperature.

[0181] In step S609, if the exhaust temperature exceeds the second preset exhaust temperature, then step S603 is executed.

[0182] In step 608, if the second difference does not reach the second preset difference, then step S610 is executed, and the opening coefficient is taken as the first opening parameter.

[0183] The first opening parameter is smaller than the second opening parameter.

[0184] In the above steps, after executing S601, step S609 can be executed, and then the other steps can be executed. Of course, the control logic for selecting the opening parameter can also have other execution orders, as long as the decision condition is executed.

[0185] The above judgment criteria are:

[0186] ①ΔTdn=Tdn-Tdn-1≥ΔTd1; ②ΔTdn-ΔTdn-1>ΔTd2 and Td>Td2;

[0187] ③Td>Td3;

[0188] If any of the above three conditions are met, the value of K is K2. If none of the above three conditions are met, the value of K is K1.

[0189] Wherein, K is the opening parameter, K1 is the first opening parameter, K2 is the second opening parameter, Td is the exhaust temperature, Td2 is the second preset exhaust temperature, Td3 is the third preset exhaust temperature, ΔTdn is the difference between the exhaust temperature at the nth start-up and the exhaust temperature at the (n-1)th temperature-controlled shutdown, ΔTd1 is the first preset difference, ΔTd2 is the second preset difference, and ΔTdn-ΔTdn-1 is used to characterize the trend of exhaust temperature change.

[0190] The exhaust temperature during the nth startup can be measured either before startup or immediately upon startup.

[0191] In some embodiments, during the operation of the air conditioning unit, the opening degree of the outdoor unit expansion valve 6 to be adjusted is obtained through a second calculation logic based on the previous opening degree and adjustment coefficient of the outdoor unit expansion valve 6.

[0192] In this application, the initial valve opening of the outdoor unit expansion valve 6 for the next temperature-controlled start-up is determined based on the exhaust temperature change trend before the temperature-controlled shutdown. This is to prevent problems such as excessively high exhaust temperature and low outlet air temperature caused by insufficient refrigerant circulation during partial load operation.

[0193] In some embodiments, when the exhaust superheat is too high, it is necessary to increase the opening of the outdoor unit expansion valve 6; when the exhaust superheat is low, it is necessary to decrease the opening of the outdoor unit expansion valve 6.

[0194] In some embodiments, the formula for increasing the opening degree of the outdoor unit expansion valve 6 is:

[0195] EVOn = EVOn-1 + EVOn-1 / L

[0196] Wherein, EVOn is the opening degree of the outdoor unit expansion valve 6 in this operation, EVOn-1 is the opening degree of the outdoor unit expansion valve 6 in the previous operation, and L is the preset coefficient.

[0197] In some embodiments, the formula for reducing the opening degree of the outdoor unit expansion valve 6 is:

[0198] EVOn = EVOn-1 - EVOn-1 / L

[0199] Wherein, EVOn is the opening degree of the outdoor unit expansion valve 6 in this operation, EVOn-1 is the opening degree of the outdoor unit expansion valve 6 in the previous operation, and L is the preset coefficient.

[0200] In some embodiments, when the exhaust superheat is too high, it is necessary to reduce the adjustment cycle of the outdoor unit expansion valve 6 in order to adjust the outdoor unit expansion valve 6 as soon as possible and adjust the refrigerant operation inside the air conditioning system.

[0201] In some embodiments, the opening of the outdoor unit expansion valve 6 is adjusted at each adjustment interval based on the opening degree and opening coefficient of the previous outdoor unit expansion valve 6 to increase the opening degree of the outdoor unit expansion valve 6.

[0202] In some embodiments, the opening of the outdoor unit expansion valve 6 is adjusted based on the adjustment cycle, which is related to one or a combination of exhaust temperature, exhaust superheat, and exhaust pressure.

[0203] In some embodiments, when the exhaust temperature does not reach the third preset exhaust temperature but exceeds the preset minimum exhaust temperature, the adjustment cycle is set to the third cycle T3.

[0204] In some embodiments, when the exhaust temperature reaches the third preset exhaust temperature but does not exceed the fourth preset exhaust temperature, the adjustment period is the second period T2.

[0205] In some embodiments, when the exhaust temperature exceeds a fourth preset exhaust temperature, the adjustment cycle is a first cycle T1.

[0206] The third preset exhaust temperature is less than the fourth preset exhaust temperature, and T1 < T2 < T3.

[0207] In this application, different valve opening cycles and different valve opening degree variables are formulated based on the set exhaust temperature, exhaust superheat, and high and low pressure design values ​​to solve the problem of excessive exhaust temperature during the operation of the air conditioning unit.

[0208] In some embodiments, when the exhaust temperature exceeds a third preset exhaust temperature, the opening of the outdoor unit expansion valve 6 is adjusted at regular intervals based on the opening degree and opening coefficient of the previous outdoor unit expansion valve 6 to increase the opening degree of the outdoor unit expansion valve 6.

[0209] Reference Figure 8 This explains the control logic for adjusting the cycle of the electronic expansion valve.

[0210] Determine whether the exhaust temperature exceeds the fourth preset exhaust temperature (S801);

[0211] In step S801, if the exhaust temperature exceeds the fourth preset exhaust temperature, it is determined that there is a lack of refrigerant in the air conditioning system at this time, and the current opening of the outdoor unit expansion valve 6 does not meet the requirements. To open the outdoor unit expansion valve 6, step S802 is executed, with the adjustment cycle being the first cycle T1. The opening of the outdoor unit expansion valve 6 is adjusted according to this adjustment cycle to increase the opening of the outdoor unit expansion valve 6, so as to adjust the opening of the outdoor unit expansion valve 6 as soon as possible and reduce the exhaust temperature.

[0212] In step S801, if the exhaust temperature does not exceed the fourth preset exhaust temperature, then step S803 is executed to determine whether the exhaust temperature exceeds the third preset exhaust temperature.

[0213] In step S803, if the exhaust temperature exceeds the third preset exhaust temperature, it means that the air conditioning unit is controlled within a controllable risk range and will not cause the unit to alarm and shut down, but it is still in the operation risk zone and needs to be quickly moved to a lower risk zone. Then, step S804 is executed, and the adjustment cycle is the second cycle T2. The opening of the outdoor unit expansion valve 6 is adjusted according to the adjustment cycle to increase the opening of the outdoor unit expansion valve 6.

[0214] In step S803, if the exhaust temperature does not exceed the third preset exhaust temperature, then step S805 is executed to determine whether the exhaust temperature exceeds the preset minimum exhaust temperature.

[0215] In step S805, if the value is greater than the target value, then step S806 is executed, the adjustment period is set to the third period T3, and the opening of the outdoor unit expansion valve 6 is adjusted according to this adjustment period to achieve the target exhaust superheat.

[0216] If the unit is operating normally at this time, only fine-tuning with PID control is needed to avoid frequent fluctuations in the air conditioning system.

[0217] In the above steps, when the exhaust temperature does not exceed the third preset exhaust temperature, the relationship between the exhaust temperature and the second preset exhaust temperature can be determined again to set the size of the adjustment cycle.

[0218] In some embodiments, a fifth preset exhaust temperature can be set, such that the fifth preset exhaust temperature is less than the third preset exhaust temperature. When the exhaust temperature is greater than the fifth preset exhaust temperature but less than the third preset exhaust temperature, an adjustment period T4 can be set again. When the exhaust temperature is less than the fifth exhaust temperature, an adjustment period T5 can be set again, where T4 is less than T5.

[0219] In some embodiments, when the exhaust temperature is low enough, the opening of the outdoor unit expansion valve 6 should not be increased further, but the valve opening of the outdoor unit expansion valve 6 should be closed quickly.

[0220] Different preset exhaust temperature levels can be set, and the adjustment cycle of the outdoor unit expansion valve 6 can be adjusted according to the different exhaust temperature levels. Generally speaking, the higher the exhaust temperature, the more urgent the need to adjust the outdoor unit expansion valve 6, and the shorter the adjustment cycle.

[0221] In some embodiments, when the exhaust temperature does not reach the preset minimum exhaust temperature and continues for a period of time, the opening of the outdoor unit expansion valve 6 is adjusted every first cycle T1 based on the opening degree and opening coefficient of the previous outdoor unit expansion valve 6 to reduce the opening degree of the outdoor unit expansion valve 6.

[0222] In some embodiments, when the exhaust temperature exceeds a preset minimum exhaust temperature...

[0223] Reference Figure 9 This explains the control logic for adjusting the opening degree of the outdoor unit expansion valve 6 based on the exhaust temperature.

[0224] Determine whether the exhaust temperature is lower than the preset minimum exhaust temperature (S901);

[0225] In step S901, if the time is less than the second preset time, then step S902 is executed to determine whether the duration has reached the second preset time.

[0226] In step S902, if the condition is met, then step S903 is executed, the adjustment period is the first period T1, and the opening of the outdoor unit expansion valve 6 is adjusted according to the adjustment period to reduce the opening of the outdoor unit expansion valve 6.

[0227] In step S901, if it is not less than, then step S904 is executed to set an adjustment period, which is greater than the first period T1, and the opening of the outdoor unit expansion valve 6 is adjusted according to the adjustment period to meet the target exhaust superheat.

[0228] In some embodiments, during air conditioner operation, exhaust superheat is calculated based on exhaust temperature and exhaust pressure;

[0229] In some embodiments, when the exhaust superheat exceeds the first preset exhaust superheat Tdsh1 but does not reach the second preset exhaust superheat Tdsh2, the adjustment cycle is set to the third cycle T3.

[0230] In some embodiments, when the exhaust superheat reaches the second preset exhaust temperature Tdsh2 but does not exceed the third preset exhaust superheat Tdsh3, the adjustment cycle is the second cycle T2.

[0231] In some embodiments, when the exhaust temperature exceeds the third preset exhaust superheat Tdsh3, the adjustment cycle is the first cycle T1;

[0232] Where Tdsh1 < Tdsh2 < Tdsh3, T1 < T2 < T3.

[0233] Reference Figure 10 This explains the control logic for adjusting the cycle of the outdoor unit expansion valve 6.

[0234] Determine whether the exhaust superheat exceeds the third preset exhaust superheat (S1001);

[0235] In step S1001, if the exhaust superheat exceeds the third preset exhaust superheat, then step S1002 is executed, the adjustment cycle is the first cycle T1, and the opening of the outdoor unit expansion valve 6 is adjusted according to the adjustment cycle to increase the opening of the outdoor unit expansion valve 6; so as to adjust the opening of the outdoor unit expansion valve 6 as soon as possible and reduce the exhaust superheat.

[0236] In step S1002, if the exhaust superheat does not exceed the third preset exhaust superheat, then step S1003 is executed to determine whether the exhaust superheat exceeds the second preset exhaust superheat.

[0237] In step S1003, if the exhaust superheat exceeds the second preset exhaust superheat, then step S1004 is executed, and the adjustment cycle is the second cycle T2; and the opening of the outdoor unit expansion valve 6 is adjusted according to the adjustment cycle to increase the opening of the outdoor unit expansion valve 6.

[0238] In step S1003, if the exhaust superheat does not exceed the second preset exhaust superheat, then step S1005 is executed to determine whether the exhaust superheat exceeds the first preset exhaust superheat.

[0239] In step S1005, if the value is exceeded, then step S1006 is executed, the adjustment cycle is set to the third cycle T3, and the opening of the outdoor unit expansion valve 6 is adjusted according to this adjustment cycle to achieve the target exhaust superheat.

[0240] In the above steps, when the exhaust superheat does not exceed the third preset exhaust superheat, the relationship between the exhaust superheat and the second preset exhaust superheat can be determined again to set the size of the adjustment cycle.

[0241] In some embodiments, when the exhaust superheat is low enough, the opening of the outdoor unit expansion valve 6 should not be increased further, but the valve opening of the outdoor unit expansion valve 6 should be closed quickly.

[0242] Different preset exhaust superheat levels can be set, and the adjustment cycle of the outdoor unit expansion valve 6 can be adjusted according to the different temperature levels of exhaust superheat. Generally speaking, the greater the exhaust superheat, the more urgent the need to adjust the outdoor unit expansion valve 6, and the shorter the adjustment cycle.

[0243] In some embodiments, during air conditioner operation, when the exhaust superheat does not reach the first preset exhaust superheat, the adjustment cycle is the first cycle T1, and the opening of the outdoor unit expansion valve 6 is adjusted according to the first cycle to reduce the opening of the outdoor unit expansion valve 6. This avoids excessive expansion of the outdoor unit expansion valve 6, which could cause liquid return to the unit and affect the reliability of the compressor.

[0244] In some embodiments, during the operation of the air conditioner, when the exhaust superheat reaches the first preset exhaust superheat but does not reach the second preset exhaust superheat, the adjustment cycle is set to the third cycle T3, and the direction of the opening adjustment is controlled according to the target exhaust superheat.

[0245] In some embodiments, during the operation of the air conditioning unit, when the suction pressure reaches below the preset low pressure value and the exhaust superheat exceeds the second preset exhaust superheat Tdsh2, the adjustment cycle is T1;

[0246] When the intake pressure reaches below the preset low pressure value, and the exhaust superheat exceeds the first preset exhaust superheat Tdsh1 but does not reach the second preset exhaust superheat Tdsh2, adjust the surrounding pressure to T2.

[0247] Where Tdsh1 < Tdsh2, T1 < T2.

[0248] Reference Figure 11 This explains the control logic of controlling the outdoor unit expansion valve 6 based on exhaust superheat and exhaust pressure.

[0249] The exhaust superheat (S1101) was calculated.

[0250] Determine whether the exhaust superheat is greater than the second preset exhaust superheat (S1102);

[0251] In step S1102, if the pressure is greater than the preset low pressure value, then step S1103 is executed to determine that the inhalation pressure has reached below the preset low pressure value.

[0252] If the target is not reached in step S1103, then step S1104 is executed, the adjustment cycle is set to the third cycle T3, and the opening of the outdoor unit expansion valve 6 is controlled according to the target exhaust superheat.

[0253] If the condition is met in step S1103, then step S1105 is executed to adjust the cycle to the first cycle T1 in order to increase the opening of the outdoor unit expansion valve 6.

[0254] In step S1102, if it is not greater than, then step 1106 is executed to determine whether the exhaust superheat has reached the first preset exhaust superheat.

[0255] In step S1106, if the condition is met, then step S1107 is executed to determine whether the inhalation pressure has reached or fallen below the preset low pressure value.

[0256] If the condition is not met in step S1107, then step S1104 is executed.

[0257] If the condition is met in step S1107, then step S1108 is executed to adjust the cycle to the second cycle T2 in order to increase the opening of the outdoor unit expansion valve 6.

[0258] If the target is not reached in step S1106, then step S1109 is executed to determine whether the exhaust superheat has reached the third preset exhaust superheat.

[0259] If the condition is met in step S1109, then step S1104 is executed.

[0260] If the target is not reached in step S1109, then step S1110 is executed to adjust the cycle to the first cycle T1 in order to reduce the opening of the outdoor unit expansion valve 6.

[0261] Among them, the third preset exhaust superheat is less than the first preset exhaust superheat is less than the second preset exhaust superheat.

[0262] The following describes one specific embodiment of this application.

[0263] When the air conditioning unit is turned on for the first time in heating mode, and the capacity ratio A is less than A1, it is determined that there are both indoor units that are turned off and indoor units that are turned on under the same operating conditions.

[0264] In some embodiments, A1 can be set to less than 1 to indicate that not all indoor units 16 are currently powered on. For example, A1 can be 0.5, 0.7, or 0.8.

[0265] The outdoor unit expansion valve 6 is opened according to the initial valve opening degree EVO1;

[0266] Record the exhaust temperature Tdn0 before the temperature control shutdown.

[0267] When the air conditioning unit is turned on by temperature control, the compressor runs at the target starting frequency H1, setting the opening of the outdoor unit expansion valve 6 to 0, and the opening of the indoor unit expansion valve 5 to 100% when the indoor unit is turned on and off.

[0268] When the start-up and exit conditions are met (for example, Td≥first preset exhaust temperature Tds), the opening degree of the outdoor unit expansion valve 6 is calculated as EVO=EV01*K, and the opening degree of the indoor unit expansion valve 5 is kept fully open when the indoor unit is turned off and when the indoor unit is turned on.

[0269] For a period of time t, the indoor unit expansion valve 5 of the shut-off indoor unit is closed to the preset opening degree m. The opening degree EVIn of the indoor unit expansion valve 5 of the turned-on indoor unit is controlled by PID according to the subcooling degree of the indoor unit 16.

[0270] In some embodiments, t can be set to be greater than t1. If t is too small, it may lead to insufficient refrigerant operation and insufficient refrigerant circulation. Therefore, t is made greater than t1, for example, t1 is 15S, 18S, or 21S. In specific designs, a suitable parameter should be selected.

[0271] In some embodiments, t can be set to be less than t2. If t is too large, it may cause refrigerant to flow to the indoor unit that is turned off, resulting in insufficient refrigerant circulation. Therefore, t is made to be less than t2. For example, t2 can be 25 seconds, 23 seconds, or 21 seconds. In specific designs, a suitable parameter should be selected.

[0272] In some embodiments, m can be set to be greater than m1. If m is too small, it may lead to excessive refrigerant pressure in the air conditioning system. Therefore, m is made to be greater than m1, for example, m1 is 2% or 3%. In specific designs, consider choosing an appropriate parameter.

[0273] In some embodiments, m can be set to be less than m2. If m is too large, it may cause refrigerant to flow to the indoor unit that is turned off, resulting in insufficient refrigerant circulation. Therefore, m is made smaller than m2. For example, m2 is 5% or 6%. In specific designs, consider choosing an appropriate parameter.

[0274] In this embodiment, the indoor unit expansion valve 5 and the outdoor unit expansion valve 6 are open at the same time. This is mainly to prevent the system refrigerant from being stored in the indoor unit when it is off, which would result in less refrigerant circulation in the indoor unit when it is on, leading to a higher exhaust temperature.

[0275] In some embodiments, when the air conditioning unit shuts down for the second time under temperature control, if the exhaust temperature before shutdown is recorded as Td, then ΔTdn = Td - Tdn0. When ΔTdn > ΔTd1, where ΔTd1 is the first preset difference, the opening parameter is satisfied to be the second opening parameter according to the coefficient before temperature control starts, i.e., K = K2. When the outdoor unit expansion valve 6 starts up next time under temperature control, the initial opening of the outdoor unit expansion valve 6 is EVO1 * K;

[0276] According to temperature detection, the refrigerant circulation in the system was low during the last operation of the air conditioning unit. Therefore, the opening of the outdoor unit expansion valve 6 needs to be increased to increase the refrigerant flow in the system when the unit is started next time.

[0277] In some embodiments, when the air conditioning unit is running, the opening of the outdoor unit expansion valve 6EVO is controlled according to the target exhaust superheat. Assuming that the unit is running at Td = 110°C > the fourth preset exhaust temperature Td3 = 108°C, the above situation indicates that the system is short of refrigerant. The current opening of the outdoor unit expansion valve 6 does not meet the requirements, and the outdoor unit expansion valve 6 needs to be opened wider. The control cycle is adjusted to once every T1 = 10 seconds.

[0278] Assuming the current electronic expansion valve EVO = 15% and L = 4, then after T1 = 10s, the electronic expansion valve opening EVO = 15% + 15% / 4 = 18.8%. If the actual detection conditions still meet the 10s cycle adjustment, then after the next 10s, the electronic expansion valve opening EVO = 18.8% + 18.8% / 4 = 23.5%, and so on.

[0279] In some embodiments, assuming that the air conditioning unit is running and the exhaust temperature Td = 105℃, the third preset exhaust temperature Td2 = 100℃ ≤ Td ≤ the fourth preset exhaust temperature Td3 = 108℃, the above situations all indicate that the unit operation is controlled within a controllable risk range and will not cause the unit to alarm and shut down, but it is still in the operation risk zone and needs to be quickly reduced to a lower risk zone. At this time, a 30-second control cycle adjustment is performed.

[0280] Assuming the current electronic expansion valve is at 15% and L = 5, then after 30 seconds, the electronic expansion valve opening EVO = 15% + 15% / 5 = 18%. If the actual detection conditions still meet the 30-second cycle adjustment, then after the next 30 seconds, the electronic expansion valve opening EVO = 18% + 18% / 5 = 21.6%, and so on.

[0281] In some embodiments, it is assumed that when the unit is running, the exhaust temperature Td = 80°C, the exhaust superheat Tdsh = 35°C, and the unit is operating close to the target exhaust superheat Tdsh0 = 30°C. The unit is operating normally and only requires fine-tuning by PID control. To avoid frequent system fluctuations, T3 = 60s.

[0282] The above solution prevents excessively high exhaust temperature, but there is a problem that the electronic expansion valve opening is too large, which can cause liquid return to the unit and affect the reliability of the compressor. The electronic expansion valve needs to be closed quickly in the following situations.

[0283] In some embodiments, assuming that the unit experiences exhaust superheat Tdsh = 5°C < first preset exhaust superheat Tdshl = 10°C during operation, and all of the above conditions satisfy a control cycle of T1 = 10s, L = 5, and assuming EVO = 40%, then the EVO after 10s = 40% - 40% / 5 = 32%. If this condition is still met, the EVO in the next 10s will be 32% - 32% / 5 = 25.6%, and so on. When this condition is not met, normal PID control is performed.

[0284] It should be noted that the above data is for illustrative purposes only and is not the only one; adjustments should be made based on the actual situation.

[0285] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has 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 therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

[0286] 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 embodiments and various different variations of the embodiments suitable for specific application considerations.

Claims

1. A multi-split air conditioner, characterized in that, include: An indoor unit comprising at least two indoor units, wherein during operation, an indoor unit in a powered-off state is defined as a powered-off indoor unit, and an indoor unit in a powered-on state is defined as a powered-on indoor unit, wherein the indoor units include: The indoor unit's expansion valve is used to regulate the refrigerant. Outdoor unit, the outdoor unit includes: A compressor, which has an intake port and an exhaust port; The outdoor unit's expansion valve is used to regulate the refrigerant. An exhaust temperature detection device is installed at the exhaust port to detect the exhaust temperature; An exhaust pressure detection device is installed at the exhaust port to detect the exhaust pressure; The controller is configured such that, after temperature-controlled shutdown, upon receiving a first signal, the outdoor unit expansion valve remains closed, while the indoor unit expansion valves of both the shut-down and start-up indoor units open, so as to allow the liquid refrigerant on the outdoor side to evaporate. When the operating parameters of the multi-split air conditioner reach the start-up and shutdown conditions, the expansion valves of the indoor units of the shut-off and the indoor units of the start-up remain open to allow the refrigerant in the shut-off indoor unit to flow into the outdoor unit. Based on the preset initial valve opening degree and opening degree parameters, the first logic operation is performed to obtain the target opening degree of the outdoor unit expansion valve in order to reduce the exhaust temperature or the exhaust pressure. The opening parameter is obtained based on a first logic judgment based on the first difference between the exhaust temperature at the previous temperature control shutdown and the exhaust temperature after the current startup. The larger the first difference, the larger the opening parameter. After working for a period of time, the indoor unit expansion valve of the shut-off indoor unit closes to the preset shutdown opening, and the indoor unit expansion valve of the start-up indoor unit is adjusted according to the subcooling degree.

2. The multi-split air conditioner according to claim 1, characterized in that, Also includes: An inhalation pressure detection device is provided at the inhalation port for detecting inhalation pressure; The controller is configured to determine that the start-up / exit conditions are met when the operating parameters of the multi-split air conditioner meet at least one of the following conditions: (1) The compressor has been running for the preset time; (2) The exhaust pressure reaches the first preset exhaust pressure; (3) The inhalation pressure reaches below the preset inhalation pressure; (4) The exhaust temperature reaches the first preset exhaust temperature.

3. The multi-split air conditioner according to claim 1, characterized in that, In the first logical operation, the opening parameter is related to the trend of the exhaust temperature change and the current exhaust temperature; The difference between the current exhaust temperature and the previous exhaust temperature is defined as the first difference, and the difference between the previous exhaust temperature and the previous two exhaust temperatures is defined as the second difference. When the difference between the second difference and the first difference exceeds the second preset difference and the exhaust temperature exceeds the second preset exhaust temperature, the opening parameter is taken as the second opening parameter; When the exhaust temperature does not reach the second preset exhaust temperature, and the first difference does not reach the first preset difference, and the difference between the second difference and the first difference does not reach the second preset difference, the opening parameter is taken as the first opening parameter. Wherein, the first preset difference is greater than the second preset difference, and the second opening parameter is greater than the first opening parameter.

4. The multi-split air conditioner according to claim 2, characterized in that, The controller is configured to, during the operation of the air conditioning unit, obtain the opening degree of the outdoor unit expansion valve to be adjusted through a second logic operation based on the previous opening degree and adjustment coefficient of the outdoor unit expansion valve; The opening of the outdoor unit expansion valve is adjusted based on the adjustment cycle, which is related to one or a combination of the exhaust temperature, exhaust superheat, and exhaust pressure.

5. The multi-split air conditioner according to claim 4, characterized in that, The controller is configured such that when the exhaust temperature does not reach the third preset exhaust temperature but exceeds the preset minimum exhaust temperature, the adjustment period is set to the third period T3. When the exhaust temperature reaches the third preset exhaust temperature but does not exceed the fourth preset exhaust temperature, the adjustment period is the second period T2; When the exhaust temperature exceeds the fourth preset exhaust temperature, the adjustment period is the first period T1; The third preset exhaust temperature is less than the fourth preset exhaust temperature, where T1 < T2 < T3.

6. The multi-split air conditioner according to claim 4, characterized in that, The controller is configured to calculate the exhaust superheat based on the exhaust temperature and exhaust pressure during the operation of the air conditioning unit. When the exhaust superheat exceeds the first preset exhaust superheat Tdsh1 but does not reach the second preset exhaust superheat Tdsh2, the adjustment cycle is set to the third cycle T3. When the exhaust superheat reaches the second preset exhaust temperature Tdsh2 and does not exceed the third preset exhaust superheat Tdsh3, the adjustment cycle is the second cycle T2. When the exhaust temperature exceeds the third preset exhaust superheat Tdsh3, the adjustment cycle is the first cycle T1; Where Tdsh1 < Tdsh2 < Tdsh3, T1 < T2 < T3.

7. The multi-split air conditioner according to claim 4, characterized in that, The controller is configured such that, during the operation of the air conditioning unit, when the suction pressure reaches below a preset low pressure value and the exhaust superheat exceeds a second preset exhaust superheat Tdsh2, the adjustment cycle is T1. When the intake pressure reaches below the preset low pressure value and the exhaust superheat reaches the first preset exhaust superheat Tdsh1 but does not reach the second preset exhaust superheat Tdsh2, the adjustment cycle is T2. Where Tdsh1 < Tdsh2, T1 < T2.

8. The multi-split air conditioner according to claim 4, characterized in that, The controller is configured such that when the exhaust superheat does not reach the first preset exhaust superheat, the adjustment cycle is set to a first cycle, and every first cycle T1 the opening of the outdoor unit expansion valve is adjusted based on the opening degree and opening coefficient of the outdoor unit expansion valve in the previous cycle, so as to reduce the opening degree of the outdoor unit expansion valve.

9. The multi-split air conditioner according to claim 4, characterized in that, When the exhaust temperature does not reach the preset minimum exhaust temperature and continues for a period of time, the opening of the outdoor unit expansion valve is adjusted every first cycle T1 based on the opening degree and opening degree coefficient of the previous outdoor unit expansion valve to reduce the opening degree of the outdoor unit expansion valve.

10. A multi-split air conditioner, characterized in that, include: An indoor unit comprising at least two indoor units, wherein during operation, an indoor unit in a powered-off state is defined as a powered-off indoor unit, and an indoor unit in a powered-on state is defined as a powered-on indoor unit, wherein the indoor units include: The indoor unit's expansion valve is used to regulate the refrigerant. Outdoor unit, the outdoor unit includes: A compressor, which has an intake port and an exhaust port; The outdoor unit's expansion valve is used to regulate the refrigerant. An exhaust temperature detection device is installed at the exhaust port to detect the exhaust temperature; An exhaust pressure detection device is installed at the exhaust port to detect the exhaust pressure; The controller is configured such that, upon receiving a first signal, the outdoor unit expansion valve remains closed, while the indoor unit expansion valves of both the shut-off and start-up indoor units open, so as to allow the liquid refrigerant on the outdoor side to evaporate. When the operating parameters of the multi-split air conditioner reach the start-up and shutdown conditions, the expansion valves of the indoor units of the shut-off and start-up indoor units remain open to allow the refrigerant in the shut-off indoor unit to flow into the outdoor unit. The target opening of the outdoor unit expansion valve is obtained by performing a first logical operation based on the preset initial valve opening degree and opening degree parameters; wherein, the opening degree parameters are at least related to the exhaust pressure. After working for a period of time, the indoor unit expansion valve of the shut-off indoor unit closes to the preset shutdown opening, and the indoor unit expansion valve of the start-up indoor unit is adjusted according to the subcooling degree.

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