Multi-connected air conditioning system and control method thereof

Abstract

The application discloses a multi-connected air conditioner system and a control method thereof, and belongs to the technical field of air treatment. The multi-connected air conditioner system comprises an air conditioner outdoor unit, a plurality of air conditioner indoor units which are arranged in one-to-one correspondence with a plurality of rooms, and a formaldehyde detection device which is used for detecting the formaldehyde concentration in the room. The control method comprises the following steps: the air conditioner indoor unit in the unoccupied room enters an aldehyde removal waiting state, the room corresponding to the air conditioner indoor unit in the aldehyde removal waiting state is referred to as an aldehyde removal waiting room; the formaldehyde concentrations of the aldehyde removal waiting rooms are compared, and the air conditioner indoor unit in the room with the lowest formaldehyde concentration enters an aldehyde forcing state; and if the compressor frequency of the air conditioner outdoor unit is lower than an upper limit value, the air conditioner indoor unit in the room with the lowest formaldehyde concentration in the current aldehyde removal waiting room enters the aldehyde forcing state. The application can shorten the release period of the formaldehyde in the room.

Description

Technical Field

[0001] This application relates to the field of air handling technology, and in particular to a multi-split air conditioning system and its control method. Background Technology

[0002] In recent years, the safety of building materials and decoration pollution have been widely discussed. Among the discussions on indoor air pollutants, formaldehyde has always been the primary target, and the potential diseases it causes have also aroused widespread public concern.

[0003] Air conditioners, as important appliances for regulating indoor air, can identify and remove air pollutants such as PM2.5, carbon dioxide, and odors, but they are somewhat inadequate in controlling formaldehyde. Most current formaldehyde removal methods can only remove formaldehyde that has already been released into the air; the formaldehyde release cycle is not shortened. Summary of the Invention

[0004] This application provides a multi-split air conditioning system and its control method, which can shorten the formaldehyde release cycle in a room.

[0005] In one aspect of this application, a multi-split air conditioning system includes: an outdoor air conditioning unit; multiple indoor air conditioning units, each corresponding to a multiple room; and a formaldehyde detection device for detecting the formaldehyde concentration in the room.

[0006] Controller, used for:

[0007] In formaldehyde removal mode, the air conditioning indoor unit in an unoccupied room enters a formaldehyde removal waiting state, and the room where the air conditioning indoor unit in the formaldehyde removal waiting state is located is called a formaldehyde removal waiting room.

[0008] Compare the formaldehyde concentration in the rooms waiting for formaldehyde removal, and put the air conditioning indoor unit in the room with the lowest formaldehyde concentration into the formaldehyde-forcing state. The room corresponding to the air conditioning indoor unit in the formaldehyde-forcing state is called the formaldehyde-forcing room.

[0009] If the compressor frequency of the outdoor unit of the air conditioner is lower than the upper frequency limit, the indoor unit of the air conditioner in the room with the lowest formaldehyde concentration in the current formaldehyde removal waiting room will be controlled to enter the formaldehyde removal state.

[0010] In some embodiments, the controller is used to: when there are multiple rooms with the lowest formaldehyde concentration in the formaldehyde removal waiting room, control the air conditioning indoor unit of one of the rooms to enter the formaldehyde-removing state.

[0011] In some embodiments, it further includes: a return air temperature detection device for detecting the return air temperature;

[0012] The controller is used for:

[0013] When the continuous formaldehyde removal time reaches the preset duration, the formaldehyde concentration in the room remains no greater than the first preset concentration value, and the return air temperature is no less than the preset formaldehyde removal temperature, the corresponding indoor air conditioning unit is controlled to exit the formaldehyde removal mode and marked as not requiring formaldehyde removal.

[0014] In some embodiments, it further includes: a return air temperature detection device for detecting the return air temperature;

[0015] The controller is used for:

[0016] When the continuous formaldehyde removal time reaches the preset duration, the formaldehyde concentration in the room remains no greater than the first preset concentration value, and the return air temperature is lower than the preset formaldehyde removal temperature, the corresponding air conditioning indoor unit will be controlled to exit the current formaldehyde removal mode.

[0017] In some embodiments, it further includes: a fresh air unit for exhausting indoor air to the outside;

[0018] The controller is used for:

[0019] When the formaldehyde concentration in the room exceeds the first preset concentration value, the fresh air unit is controlled to enter the formaldehyde release state.

[0020] When the formaldehyde concentration in the room is not greater than the first preset concentration value, the air conditioning indoor unit of that room is controlled to re-enter the formaldehyde removal waiting state.

[0021] In some embodiments, the controller is used to:

[0022] When the indoor unit of the air conditioner re-enters the formaldehyde removal waiting state, record the number of formaldehyde removal times for that indoor unit.

[0023] By comparing the number of formaldehyde removal cycles of air conditioning indoor units that are in a formaldehyde removal waiting state, the air conditioning indoor unit with the fewest formaldehyde removal cycles can be identified.

[0024] Compare the formaldehyde concentration in the rooms corresponding to the air conditioning indoor unit with the fewest formaldehyde removal cycles;

[0025] The air conditioning unit in the room with the lowest formaldehyde concentration enters a formaldehyde-reducing state.

[0026] In some embodiments, it further includes: a fresh air unit for exhausting indoor air to the outside;

[0027] In the formaldehyde-reducing state, the indoor air conditioning unit operates at the highest fan speed in heating mode to raise the indoor temperature to the preset formaldehyde-reducing temperature; in the formaldehyde-releasing state, the fresh air unit operates at the highest fan speed.

[0028] In some embodiments, it further includes: a humidification unit;

[0029] The controller is used for:

[0030] When the formaldehyde-repelling state is activated, the indoor air conditioning unit is controlled to operate in heating mode at the highest fan speed to raise the indoor temperature to the preset formaldehyde-repelling temperature, and the humidification unit is activated.

[0031] In some embodiments, when no one is in the room and the indoor air conditioning unit is not in cooling mode, the indoor air conditioning unit enters a formaldehyde removal waiting state.

[0032] Another aspect of this application is a control method for a multi-split air conditioning system, comprising: in a formaldehyde removal mode, detecting whether there are people in the room and detecting the formaldehyde concentration in the room;

[0033] The air conditioning indoor unit in an unoccupied room enters a formaldehyde removal waiting state. The room corresponding to the air conditioning indoor unit in the formaldehyde removal waiting state is called a formaldehyde removal waiting room.

[0034] Compare the formaldehyde concentrations in the rooms waiting for formaldehyde removal; the air conditioning unit in the room with the lowest formaldehyde concentration will enter the formaldehyde-removing state.

[0035] If the compressor frequency of the outdoor unit of the air conditioner is lower than the upper frequency limit, the indoor unit of the air conditioner in the room with the lowest formaldehyde concentration in the current formaldehyde removal waiting room will enter the formaldehyde removal state. Attached Figure Description

[0036] Figure 1 This is a diagram showing the appearance of a multi-split air conditioning system according to an embodiment;

[0037] Figure 2 This is a diagram illustrating the refrigerant circuit of a multi-split air conditioning system according to an embodiment;

[0038] Figure 3 This is a control block diagram illustrating the components of a multi-split air conditioning system according to an embodiment;

[0039] Figure 4 This illustrates the process of operating the formaldehyde removal mode of a multi-split air conditioning system according to an embodiment. Figure 1 ;

[0040] Figure 5 This illustrates the process of operating the formaldehyde removal mode of a multi-split air conditioning system according to an embodiment. Figure 2 ;

[0041] Figure 6 This illustrates the process of operating the formaldehyde removal mode of a multi-split air conditioning system according to an embodiment. Figure 3 ;

[0042] In the above diagrams, 10 is the outdoor unit of the air conditioner; 11 is the compressor; 12 is the outdoor heat exchanger; 13 is the four-way valve; 14 is the outdoor expansion valve; 20 is the indoor unit of the air conditioner; 21 is the indoor heat exchanger; 22 is the indoor expansion valve; 23 is the formaldehyde adsorption module; 30 is the humidification unit; 40 is the fresh air unit; 51 is the controller; 52 is the memory; 53 is the formaldehyde detection device; 54 is the human presence detection device; 55 is the return air temperature detection device; 56 is the input device; and 57 is the display. Detailed Implementation

[0043] To make the objectives and implementation methods of this application clearer, the exemplary implementation methods of this application will be clearly and completely described below with reference to the accompanying drawings of the exemplary embodiments of this application. Obviously, the exemplary embodiments described are only some embodiments of this application, and not all embodiments.

[0044] In the description of this application, it should be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0045] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "multiple" means two or more.

[0046] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0047] Figure 1 This is a diagram showing the appearance of a multi-split air conditioning system according to an embodiment.

[0048] Reference Figure 1According to an embodiment of this application, a multi-split air conditioning system includes: an outdoor air conditioning unit 10, located in an outdoor space and used to perform heat exchange between refrigerant and outdoor air; and a plurality of indoor air conditioning units 20: indoor air conditioning unit 20-1, indoor air conditioning unit 20-2, indoor air conditioning unit 20-3, ... and indoor air conditioning unit 20-n, the indoor air conditioning units 20 being located in an indoor space and used to perform heat exchange between refrigerant and indoor air. Figure 1 The multi-split air conditioning system shown includes a single outdoor air conditioning unit 10, but is not limited thereto; therefore, the multi-split air conditioning system may include two or more outdoor air conditioning units.

[0049] Typically, each air conditioning indoor unit 20 is located in one room. For example, air conditioning indoor unit 20-1 is located in room 1, air conditioning indoor unit 20-2 is located in room 2, air conditioning indoor unit 20-3 is located in room 3, ..., air conditioning indoor unit 20-n is located in room n.

[0050] Figure 2 This is a diagram illustrating the refrigerant circuit of a multi-split air conditioning system according to an embodiment.

[0051] Reference Figure 2 The outdoor unit 10 of the air conditioner includes: a compressor 11 for compressing refrigerant; an outdoor heat exchanger 12 for performing heat exchange between outdoor air and refrigerant; a four-way valve 13 for selectively guiding the refrigerant compressed by the compressor 11 to the outdoor heat exchanger 12 or the indoor unit 20 of the air conditioner, depending on the heating or cooling mode; and an outdoor expansion valve 14 for reducing the pressure of the refrigerant to be guided to the outdoor heat exchanger 12 in the heating mode.

[0052] The indoor air conditioning unit 20 includes: an indoor heat exchanger 21 that performs heat exchange between indoor air and refrigerant; and an indoor expansion valve 22 that reduces the pressure of the refrigerant supplied to the indoor heat exchanger 21 during cooling.

[0053] When the indoor unit 20 of the air conditioner is in cooling mode, the compressor 11 of the outdoor unit 10 compresses the refrigerant to a high pressure and guides the compressed refrigerant to the outdoor heat exchanger 12 through the four-way valve 13. The compressed refrigerant condenses in the outdoor heat exchanger 12, and during condensation, the refrigerant releases its latent heat to the outdoor air. The condensed refrigerant then enters the indoor unit 20.

[0054] The indoor expansion valve 14 in the indoor air conditioning unit 20 reduces the pressure of the refrigerant, which is then evaporated in the indoor heat exchanger 21. In cooling mode, the multi-split air conditioning system can cool the indoor air by utilizing the heat exchange between the refrigerant in the indoor heat exchanger 12 and the indoor air.

[0055] The refrigerant continues to flow to the outdoor unit 10 of the air conditioner, and returns to the compressor 11 through the four-way valve 13, thus repeating the above refrigerant cycle.

[0056] In cooling mode, the multi-split air conditioning system absorbs heat energy from the indoor air in the indoor unit 20 and releases the heat energy to the outdoor space in the outdoor unit 10, thereby discharging indoor heat energy to the outside.

[0057] When the indoor unit 20 is in heating mode, the compressor 11 of the outdoor unit 10 compresses the refrigerant to high pressure and guides the compressed refrigerant to the indoor unit 20 through the four-way valve 13. The indoor heat exchanger 21 in the indoor unit 20 condenses the refrigerant. In heating mode, the multi-split air conditioning system can heat the indoor air by utilizing the heat exchange between the refrigerant in the indoor heat exchanger 21 and the indoor air. The refrigerant then continues to flow into the outdoor unit 10.

[0058] The outdoor expansion valve 14 in the outdoor unit 10 of the air conditioner reduces the pressure of the refrigerant, which then evaporates in the outdoor heat exchanger 12. The refrigerant returns to the compressor 11 through the four-way valve 13, thus repeating the above refrigerant cycle.

[0059] In heating mode, the multi-split air conditioning system absorbs heat energy from the outdoor air in the outdoor unit 10 and discharges the heat energy into the indoor space in the indoor unit 20, thereby transferring outdoor heat energy into the indoor space.

[0060] When renovating or refurbishing a house, the furniture and wood-based panels used indoors contain large amounts of formaldehyde, which can affect human health. Without external intervention, it takes a considerable amount of time for the formaldehyde in the furniture to dissipate into the air.

[0061] The multi-split air conditioning system of this application has a formaldehyde removal mode, which can target formaldehyde in the room, thereby quickly removing formaldehyde from furniture and shortening the formaldehyde removal cycle.

[0062] The formaldehyde removal mode has a formaldehyde removal waiting state. In the formaldehyde removal waiting state: the indoor air conditioning unit 20 is in standby mode, or the indoor air conditioning unit 20 is in low fan speed mode.

[0063] In the low-speed air supply mode, the indoor heat exchanger 21 of the air conditioning indoor unit 20 is not activated, and only the indoor fan operates at a low speed.

[0064] The formaldehyde removal mode includes a formaldehyde-forcing state. In this state, the indoor air conditioning unit 20 operates in heating mode to heat the indoor air, raising its temperature to a preset formaldehyde-forcing temperature, such as 32°C. This creates conditions conducive to formaldehyde volatilization, accelerating the release of formaldehyde from the furniture.

[0065] Under formaldehyde-reducing conditions, the indoor fan of the air conditioning indoor unit 20 can operate at its highest speed to rapidly raise the indoor air temperature and accelerate the volatilization of formaldehyde.

[0066] In some embodiments, refer to Figure 1 The multi-split air conditioning system includes a humidification unit 30 to increase the humidity of the indoor air. Since higher humidity leads to faster formaldehyde evaporation, this application utilizes the humidification unit 30 to further accelerate the evaporation rate of formaldehyde.

[0067] The humidification unit 30 and the air conditioning indoor unit 20 can be installed in one indoor unit; or the humidification unit 30 and the air conditioning indoor unit 20 can be two independent devices. For example, the humidification unit 30 is installed in the humidifier and the air conditioning indoor unit 20 is installed in the air conditioning indoor unit.

[0068] In some embodiments, the air conditioning indoor unit 20 includes a formaldehyde adsorption module 23 for adsorbing formaldehyde in the air. While the air conditioning indoor unit 20 uses heating to cause formaldehyde to volatilize, it also uses the formaldehyde adsorption module 23 to remove formaldehyde from the air.

[0069] In some embodiments, the multi-split air conditioning system includes a fresh air unit 40 for exhausting indoor air to the outside.

[0070] The formaldehyde removal mode includes a formaldehyde release mode. In this mode, the fan in the fresh air unit 40 can operate at its highest speed, quickly exhausting indoor air to the outside to rapidly remove formaldehyde from the room.

[0071] The fresh air unit 40 and the air conditioning indoor unit 20 can be installed in one air conditioning indoor unit; or the fresh air unit 40 and the air conditioning indoor unit 20 can be two independent devices. For example, the fresh air unit 40 is installed in the fresh air unit, and the air conditioning indoor unit 20 is installed in the air conditioning indoor unit.

[0072] According to the embodiment, the fresh air unit 40 can exhaust indoor air to the outside and simultaneously bring fresh outdoor air into the room, thereby exchanging the indoor air.

[0073] The following section will describe the signal flow between components in a multi-split air conditioning system.

[0074] Reference Figure 3The multi-split air conditioning system includes: a controller 51, used to control the operating status of the outdoor unit 10, indoor unit 20, humidification unit 30, and fresh air unit 40 according to the formaldehyde concentration in the room; a memory 52, used to store programs and data related to the operation of the multi-split air conditioning system; a formaldehyde detection device 53, used to detect the formaldehyde concentration in the room; a human presence detection device 54, used to detect whether there are people in the room; a return air temperature detection device 55, used to detect the return air temperature; an input device 56, used to receive operation commands from the user; and a display 57, used to display operation information.

[0075] When the multi-split air conditioning system is in formaldehyde removal mode, the controller 51 can control the indoor air conditioning unit 20 to be in standby mode while in formaldehyde removal waiting state.

[0076] In the formaldehyde-reducing state, the controller 51 can control the indoor air conditioning unit 20 to be in heating mode. Specifically, the controller can control the compressor 11 to compress the refrigerant, control the four-way valve 13 to supply the compressed refrigerant to the indoor air conditioning unit 20, control the indoor heat exchanger 21 to condense the compressed refrigerant supplied from the outdoor air conditioning unit 10, control the outdoor expansion valve 14 to depressurize the liquid refrigerant supplied from the indoor air conditioning unit 20, and control the outdoor heat exchanger 12 to evaporate the depressurized liquid refrigerant.

[0077] In addition, the controller 51 can control the humidification unit 30 to be turned on.

[0078] In the formaldehyde-releasing state, the controller 51 can control the start of the fan of the fresh air unit 40 to exhaust the indoor air containing formaldehyde to the outside.

[0079] According to an embodiment, the controller 51 can switch the system between a formaldehyde removal waiting state, a formaldehyde forcing state, and a formaldehyde release state based on the formaldehyde concentration in the room.

[0080] According to an embodiment, the controller 51 can control which of the air-conditioning indoor units 20 enters the formaldehyde-repelling state based on the formaldehyde concentration in the room and the frequency of the compressor.

[0081] According to an embodiment, the controller 51 can control the indoor air conditioning unit to exit the formaldehyde removal mode based on changes in formaldehyde concentration in the room, return air temperature, and duration of formaldehyde removal.

[0082] The controller 51 may include: at least one memory for storing a program for performing the operations described above and later; and at least one processor for executing the stored program. When multiple memories and processors are present, they may be integrated on a single chip or located in physically separate locations.

[0083] The memory 52 can store programs and data related to state changes in the formaldehyde removal mode. Specifically, the memory 52 can store the formaldehyde forcing duration, the formaldehyde concentration value indicating the transition from the formaldehyde forcing state to the formaldehyde releasing state, the formaldehyde concentration value indicating the transition from the formaldehyde releasing state to the formaldehyde removal waiting state, and the temperature value to be reached by the air conditioning indoor unit 20 for heating.

[0084] To store various types of information, memory 52 may be implemented by at least one of non-volatile memory (such as cache, read-only memory (ROM), programmable ROM (PROM), erasable programmable ROM (EPROM) and flash memory), volatile memory (such as random access memory (RAM)), or storage media such as hard disk drive (HDD) and CD-ROM, but is not limited thereto.

[0085] According to the embodiment, the formaldehyde detection device 53 outputs an electrical signal corresponding to the detected formaldehyde concentration. The human detection device 54 outputs an electrical signal corresponding to the detected human body; the human detection device 54 can be an infrared sensor.

[0086] According to an embodiment, the input device 56 can receive input from a user. The input device 56 may include a push-button switch, membrane switch, touch panel, control panel, etc., for receiving operating commands for the multi-split air conditioning system. Exemplarily, the input device 56 may be a remote control, a wired controller, or an app.

[0087] According to an embodiment, the display 57 may be a display panel that displays operation information of a multi-split air conditioning system.

[0088] The following section describes the method for removing formaldehyde from a multi-split air conditioning system.

[0089] Reference Figure 4 After receiving the formaldehyde removal command from the user, the multi-split air conditioning system enters the formaldehyde removal mode (step 1).

[0090] The formaldehyde removal mode is best used when no one is in the room. When no one is in the room, the multi-split air conditioning system does not need to consider the user's comfort when controlling temperature and humidity. Therefore, the room temperature and humidity can be kept at a higher level to create conditions conducive to formaldehyde volatilization. In addition, when no one is in the room, the harm of formaldehyde volatilization to the human body does not need to be considered.

[0091] Whether someone is in the room can be determined by a human detection device or by user settings.

[0092] If the data is obtained through a human detection device, the detection time can be extended to ensure the continuity of the results. For example, if no one is detected for 5 or 10 consecutive minutes, the room is considered empty. This avoids situations where a person briefly enters the room and is mistakenly identified as occupied.

[0093] The air conditioning unit in the unoccupied room enters the formaldehyde removal waiting state (step 2).

[0094] While waiting for formaldehyde removal, the indoor unit of the air conditioner is either in standby mode or in low fan speed mode.

[0095] Compare the formaldehyde concentrations in the waiting rooms for formaldehyde removal (step 3). The waiting room for formaldehyde removal is the room containing the air-conditioned indoor unit that is in the formaldehyde removal waiting state.

[0096] The formaldehyde detection device monitors the formaldehyde concentration in the room in real time and compares the concentration values ​​to determine the room with the lowest concentration.

[0097] The air conditioning unit in the room with the lowest formaldehyde concentration enters the formaldehyde-reducing state (step 4).

[0098] Determine if the compressor frequency of the outdoor unit of the air conditioner is lower than the upper frequency limit (step 5); if yes, return to step 3 and compare the formaldehyde concentration in the room currently waiting for formaldehyde removal; if no, maintain the number of indoor units of the air conditioner that have entered the formaldehyde removal state.

[0099] In step 5, the upper limit of frequency can be the upper limit of the compressor's rated operating frequency, or the upper limit of frequency can be the maximum frequency value when the system performs frequency control on the compressor.

[0100] Among them, the "formaldehyde-entrained room" refers to the room where the air-conditioned indoor unit is located in a formaldehyde-entrained state.

[0101] Possible reasons for low formaldehyde concentration in a room: (1) There is no furniture in the room, or the formaldehyde in the furniture has already evaporated, so the room does not actually need formaldehyde removal (green room); (2) There is less formaldehyde-containing furniture in the room than in other rooms; (3) The formaldehyde in the room evaporates more slowly than in other rooms.

[0102] If the cause is (1), formaldehyde removal should be prioritized for the room so that users can know that the room is a green room as soon as possible, which will facilitate the normal use of the room.

[0103] If it is reason (2), prioritize the removal of formaldehyde from the room so that the room with less formaldehyde can become a green room as soon as possible, thereby increasing the number of green rooms in a short period of time and facilitating the normal use of green rooms by users.

[0104] If it is reason (3), the formaldehyde in the room is not easy to volatilize, and it is even more necessary to use external means to make the formaldehyde volatilize in advance.

[0105] If all air conditioning indoor units that are in the formaldehyde removal waiting state enter the formaldehyde removal state, the system will consume a lot of energy because the formaldehyde removal temperature required for heating is relatively high. The system may be overloaded and its service life will be affected. In addition, multiple machines working at the same time will slow down the time it takes for each room to reach the formaldehyde removal temperature, and the formaldehyde removal effect cannot be achieved in a short time.

[0106] In this application, the number of indoor air conditioning units entering the formaldehyde-removing state is controlled according to the compressor frequency, which can maximize the use of the air conditioning system for formaldehyde removal and give full play to the heating function of the air conditioning system.

[0107] For example, in actual operating conditions, if the difference between the indoor temperature and the preset formaldehyde-reducing temperature is small, the compressor can operate at a low frequency. In this case, the number of air conditioning indoor units that enter the formaldehyde-reducing state can be increased. If the difference between the indoor temperature and the preset formaldehyde-reducing temperature is large and the indoor temperature is low, the compressor needs to operate at a high frequency. In this case, a small number of air conditioning indoor units can enter the formaldehyde-reducing state.

[0108] After the formaldehyde-reducing state continues for a preset time in step 4, proceed to step 6 to determine whether the formaldehyde concentration in the room does not exceed the first preset concentration value; if yes, proceed to step 7; if no, proceed to step 8.

[0109] Step 7: Determine if the indoor return air temperature is lower than the preset formaldehyde removal temperature. If yes, exit the formaldehyde removal mode for this room (Step 71); if no, exit the formaldehyde removal mode for this room and mark the room as a green room (Step 72).

[0110] If the indoor formaldehyde concentration is relatively low after the air conditioner's indoor unit has been heating for the preset duration, but the return air temperature has not reached the preset formaldehyde removal temperature, it indicates that the doors and windows of the room may not be closed. The current state of the room is not suitable for formaldehyde removal, and the current formaldehyde removal mode can be exited.

[0111] If the air conditioner indoor unit reaches the preset heating duration and the return air temperature reaches the preset formaldehyde removal temperature, but the indoor formaldehyde concentration remains relatively low, it indicates that the room does not require formaldehyde removal and can be marked as a green room. The air conditioner indoor unit in a green room does not participate in the formaldehyde removal mode.

[0112] If the user cancels the green room label, the indoor unit of the air conditioner can re-enter the formaldehyde removal mode.

[0113] Step 8: The control system enters the formaldehyde release state: the fan of the fresh air unit rotates remotely to expel indoor air containing formaldehyde.

[0114] After the formaldehyde-inducing state has lasted for a period of time, the fresh air unit can be turned on to exhaust the indoor air in order to achieve the purpose of formaldehyde removal.

[0115] In other embodiments, refer to Figure 5 Before step 8, step 9 can be added: continue to determine whether the formaldehyde concentration in the room is not less than the second preset concentration value. If so, the control system enters the formaldehyde release state: the fan of the fresh air unit rotates to exhaust the indoor air containing formaldehyde (step 8); if not, continue to step 4, so that the indoor air conditioning unit works in the formaldehyde release state.

[0116] If the formaldehyde concentration in the room has not yet reached the second preset concentration value, it means that the formaldehyde removal effect is not ideal, and the formaldehyde removal time can be appropriately extended.

[0117] When formaldehyde is released, the indoor unit of the air conditioner can be in standby mode or in low fan speed mode.

[0118] After a period of time, the formaldehyde concentration in the room will decrease.

[0119] Reference Figure 6 Step 101: Determine whether the formaldehyde concentration in the room is not greater than the first preset concentration value. If so, control the fresh air unit of the room to stop running (step 102) and control the indoor air conditioning unit of the room to enter the formaldehyde removal waiting state.

[0120] In other embodiments, step 101 involves determining whether the formaldehyde concentration in the room is not greater than a first preset concentration value. If so, the fresh air unit in the room is controlled to stop operating (step 102), and the indoor air conditioning unit in the room is controlled to re-enter the formaldehyde removal waiting state, and the number of formaldehyde removals by the indoor air conditioning unit is recorded (step 103). If not, step 8 is continued.

[0121] In step 103, the formaldehyde removal count refers to the number of times the air conditioning indoor unit has undergone formaldehyde removal. Each time the air conditioning indoor unit enters the formaldehyde removal state, the formaldehyde removal count for that unit is incremented by one.

[0122] Step 104: Compare the number of formaldehyde removal cycles of the air conditioning indoor units that are in the formaldehyde removal waiting state, and identify the air conditioning indoor unit with the fewest formaldehyde removal cycles.

[0123] Step 105: Compare the formaldehyde concentration in the room corresponding to the air-conditioned indoor unit with the fewest formaldehyde removal cycles, identify the room with the lowest formaldehyde concentration, and then proceed to step 4.

[0124] In step 105, if there are two or more air-conditioned indoor units with the fewest formaldehyde removal cycles, the formaldehyde concentration needs to be compared. If there is only one air-conditioned indoor unit with the fewest formaldehyde removal cycles, the room containing that air-conditioned indoor unit is directly identified as the room with the lowest formaldehyde concentration.

[0125] If the lowest formaldehyde concentration is always used as the sole criterion for determining whether an air conditioner's indoor unit enters a formaldehyde-removing state, then there will be situations where formaldehyde removal is continuously performed on the same room while other rooms fail to be removed. For example, the room with the lowest formaldehyde concentration no longer needs formaldehyde removal, but due to air circulation between rooms, this room may never be marked as a "green room" and will continue to be subjected to formaldehyde removal, wasting the air conditioner's efforts.

[0126] Therefore, in the embodiments of this application, the lowest formaldehyde concentration room and the number of formaldehyde removal times are used as the judgment conditions for the air-conditioning indoor unit to enter the formaldehyde-removing state, which can avoid the system's wasted efforts and ensure that each room can be removing formaldehyde.

[0127] As described above, in the multi-split air conditioning system according to this application, using the room with the lowest formaldehyde concentration as the condition for formaldehyde removal in the air conditioning indoor unit can identify green rooms earlier, thereby providing a basis for users to use the room.

[0128] In addition, by controlling the number of air conditioning indoor units entering the formaldehyde-removing state according to the compressor frequency, the heating capacity of the air conditioner can be utilized to the maximum extent to remove formaldehyde, thus improving the efficiency of formaldehyde removal.

[0129] In addition, identifying green rooms based on return air temperature and formaldehyde concentration in the room can avoid the system's ineffective formaldehyde removal from green rooms.

[0130] In addition, identifying open rooms (with doors and windows open) based on return air temperature and formaldehyde concentration in the room can prevent the system from ineffectively removing formaldehyde from open rooms.

[0131] In addition, controlling the indoor air conditioning units that require fewer formaldehyde removal cycles to enter the formaldehyde-removing state first can avoid the system working in vain and ensure that all rooms are free of formaldehyde.

[0132] 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.

[0133] For ease of explanation, the above description has been provided in conjunction with specific embodiments. However, the above exemplary discussion is not intended to be exhaustive or to limit the embodiments to the specific forms disclosed above. Various modifications and variations can be obtained based on the above teachings. The selection and description of the above embodiments are for the purpose of better explaining the principles and practical applications, thereby enabling those skilled in the art to better utilize the described embodiments and various different variations of embodiments suitable for specific use considerations.

Claims

1. A multi-split air conditioning system, characterized in that, include: Air conditioning outdoor unit; Multiple indoor air conditioning units are set up, one for each of the multiple rooms; Formaldehyde detection device, used to detect formaldehyde concentration in a room; A fresh air unit is used to exhaust indoor air to the outside. Controller, used for: In formaldehyde removal mode, the air conditioning indoor unit in an unoccupied room enters a formaldehyde removal waiting state, and the room where the air conditioning indoor unit in the formaldehyde removal waiting state is located is called a formaldehyde removal waiting room. Compare the formaldehyde concentration in the rooms waiting for formaldehyde removal, and put the air conditioning indoor unit in the room with the lowest formaldehyde concentration into the formaldehyde-forcing state. The room corresponding to the air conditioning indoor unit in the formaldehyde-forcing state is called the formaldehyde-forcing room. If the compressor frequency of the outdoor unit of the air conditioner is lower than the upper limit of the frequency, the indoor unit of the air conditioner in the room with the lowest formaldehyde concentration in the room currently waiting for formaldehyde removal will be controlled to enter the formaldehyde removal state. The controller is also used for: When the formaldehyde concentration in the room exceeds the first preset concentration value, the fresh air unit is controlled to enter the formaldehyde release state. When the formaldehyde concentration in the room is not greater than the first preset concentration value, the air conditioning indoor unit of the room is controlled to re-enter the formaldehyde removal waiting state. When the indoor unit of the air conditioner re-enters the formaldehyde removal waiting state, record the number of formaldehyde removal times for that indoor unit. By comparing the number of formaldehyde removal cycles of air conditioning indoor units that are in a formaldehyde removal waiting state, the air conditioning indoor unit with the fewest formaldehyde removal cycles can be identified. Compare the formaldehyde concentration in the rooms corresponding to the air conditioning indoor unit with the fewest formaldehyde removal cycles; The air conditioning unit in the room with the lowest formaldehyde concentration enters a formaldehyde-repelling state.

2. The multi-split air conditioning system according to claim 1, characterized in that, The controller is used for: When there are multiple rooms with the lowest formaldehyde concentration in the waiting room for formaldehyde removal, the air conditioning indoor unit of one of these rooms is controlled to enter the formaldehyde-removing state.

3. The multi-split air conditioning system according to claim 1, characterized in that, Also includes: Return air temperature detection device, used to detect return air temperature; The controller is used for: When the continuous formaldehyde removal time reaches the preset duration, the formaldehyde concentration in the room remains no greater than the first preset concentration value, and the return air temperature is no less than the preset formaldehyde removal temperature, the corresponding indoor air conditioning unit is controlled to exit the formaldehyde removal mode and marked as not requiring formaldehyde removal.

4. The multi-split air conditioning system according to claim 1, characterized in that, Also includes: Return air temperature detection device, used to detect return air temperature; The controller is used for: When the continuous formaldehyde removal time reaches the preset duration, the formaldehyde concentration in the room remains no greater than the first preset concentration value, and the return air temperature is lower than the preset formaldehyde removal temperature, the corresponding air conditioning indoor unit will be controlled to exit the current formaldehyde removal mode.

5. The multi-split air conditioning system according to claim 1, characterized in that, Also includes: A fresh air unit is used to exhaust indoor air to the outside. In the formaldehyde-removing state, the indoor air conditioning unit operates at the highest fan speed in heating mode to raise the indoor temperature to the preset formaldehyde-removing temperature. In the formaldehyde-releasing state, the fresh air unit operates at the highest fan speed.

6. The multi-split air conditioning system according to claim 1, characterized in that, Also includes: Humidification unit; The controller is used for: When the formaldehyde-repelling state is activated, the indoor air conditioning unit is controlled to operate in heating mode at the highest fan speed to raise the indoor temperature to the preset formaldehyde-repelling temperature, and the humidification unit is activated.

7. The multi-split air conditioning system according to claim 1, characterized in that, When no one is in the room and the indoor unit of the air conditioner is not in cooling mode, the indoor unit of the air conditioner enters a formaldehyde removal waiting state.

8. A control method for a multi-split air conditioning system, characterized in that, The multi-split air conditioning system includes: Air conditioning outdoor unit; and A fresh air unit is used to exhaust indoor air to the outside. Multiple indoor air conditioning units are set up, one for each of the multiple rooms; The control method includes: In formaldehyde removal mode, it detects whether anyone is in the room and measures the formaldehyde concentration in the room. The air conditioning indoor unit in an unoccupied room enters a formaldehyde removal waiting state. The room corresponding to the air conditioning indoor unit in the formaldehyde removal waiting state is called a formaldehyde removal waiting room. Compare the formaldehyde concentrations in the rooms waiting for formaldehyde removal; the air conditioning unit in the room with the lowest formaldehyde concentration will enter the formaldehyde-removing state. If the compressor frequency of the outdoor unit of the air conditioner is lower than the upper limit of the frequency, the indoor unit of the air conditioner in the room with the lowest formaldehyde concentration in the room currently waiting for formaldehyde removal will enter the formaldehyde removal state. When the formaldehyde concentration in the room exceeds the first preset concentration value, the fresh air unit is controlled to enter the formaldehyde release state. When the formaldehyde concentration in the room is not greater than the first preset concentration value, the air conditioning indoor unit of the room is controlled to re-enter the formaldehyde removal waiting state. When the indoor unit of the air conditioner re-enters the formaldehyde removal waiting state, record the number of formaldehyde removal times for that indoor unit. By comparing the number of formaldehyde removal cycles of air conditioning indoor units that are in a formaldehyde removal waiting state, the air conditioning indoor unit with the fewest formaldehyde removal cycles can be identified. Compare the formaldehyde concentration in the rooms corresponding to the air conditioning indoor unit with the fewest formaldehyde removal cycles; The air conditioning unit in the room with the lowest formaldehyde concentration enters a formaldehyde-repelling state.

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