Energy-saving control method and device for indoor unit of multi-connected system and multi-connected air conditioner

Abstract

The application provides a multi-connected system indoor unit energy-saving control method and device and a multi-connected air conditioner. The method comprises the following steps: in the case of refrigeration operation, if multiple indoor units are in an open state, the expansion valve opening degree, inlet pipe temperature and outlet pipe temperature of each indoor unit are obtained; if the expansion valve opening degree of the indoor unit is the minimum opening degree and the inlet pipe temperature is greater than or equal to the outlet pipe temperature, the following regulation and control process is performed: if the user set temperature is greater than a threshold value, the outdoor unit refrigeration output level is reduced; if the user set temperature is less than or equal to the threshold value and the environment temperature is less than or equal to a threshold value, the expansion valve is switched between the minimum opening degree and the closed state or is closed according to the environment temperature; if the user set temperature is less than or equal to the threshold value and the environment temperature is greater than the threshold value, if the current air damper of the indoor unit is not the maximum air damper, the current air damper is increased by at least one level. The application can make the refrigerant evaporate completely as much as possible, play the due refrigeration effect, avoid liquid return, reduce energy consumption, improve system reliability and take into account user comfort.

Description

Technical Field

[0001] This invention relates to the field of automatic shutdown control technology for air conditioners, and more specifically, to an energy-saving control method, device, and air conditioner for the indoor unit of a multi-split air conditioning system. Background Technology

[0002] In actual installation scenarios of multi-split central air conditioning systems, a single system typically contains multiple indoor units and one or more outdoor units. Depending on the installation area and requirements, a multi-split system may have both large-capacity and small-capacity indoor units coexisting within the same system. During the cooling operation of the air conditioning system, when both large and small-capacity indoor units are turned on simultaneously, the refrigerant evaporation temperature is the same. Because the smaller-capacity indoor unit has a smaller heat exchanger, its refrigerant capacity is lower when the heat exchange airflow is low and the ambient temperature is low. Even after the indoor unit valve reaches its minimum opening, a relatively large amount of refrigerant remains, which cannot evaporate completely. This results in an excessively low outlet pipe temperature, failing to meet the superheat requirements of the indoor unit, leading to liquid return, affecting system reliability, and causing energy waste. Summary of the Invention

[0003] To address the aforementioned problems, this invention provides an energy-saving control method for the indoor units of a multi-split air conditioning system. The method includes: when multiple indoor units are on during cooling operation, acquiring the expansion valve opening, inlet pipe temperature, and outlet pipe temperature of each indoor unit; if the expansion valve opening of an indoor unit is at its minimum and the inlet pipe temperature is greater than or equal to the outlet pipe temperature, controlling the indoor unit to execute an energy-saving control process; the energy-saving control process includes: reducing the outdoor unit's cooling output level when the user-set temperature is greater than a suitable temperature threshold; and reducing the outdoor unit's cooling output level when the user-set temperature is less than or equal to the suitable temperature threshold. If the indoor ambient temperature is less than or equal to the suitable temperature threshold, and the indoor ambient temperature is greater than the user-set temperature and the difference is greater than the temperature difference threshold, then the opening of the expansion valve is controlled to switch between minimum opening and closed. If the indoor ambient temperature is greater than the user-set temperature and the difference is less than or equal to the temperature difference threshold, then the expansion valve is controlled to close. If the user-set temperature is less than or equal to the suitable temperature threshold and the indoor ambient temperature is greater than the suitable temperature threshold, and the current fan speed of the indoor unit is not the maximum fan speed, then the current fan speed is increased by at least one level.

[0004] The indoor unit energy-saving control method for multi-split air conditioning systems provided in this invention can determine the refrigerant evaporation status by measuring the expansion valve opening, the inlet pipe temperature, and the outlet pipe temperature of the indoor unit. If the refrigerant is not completely evaporated and there is a risk of liquid return, the indoor unit energy-saving control process is executed. By adjusting the expansion valve opening and the indoor unit fan speed, the refrigerant can be made to evaporate as completely as possible, achieve the desired cooling effect, avoid the risk of liquid return, reduce energy consumption, improve system reliability, and take into account user comfort.

[0005] Optionally, the indoor unit energy-saving control process further includes: if the user-set temperature is greater than the suitable temperature threshold, and the inlet pipe temperature is less than the suitable temperature threshold, then the expansion valve is controlled to close; if the inlet pipe temperature is greater than or equal to the suitable temperature threshold, then the opening degree of the expansion valve is controlled to be the minimum opening degree.

[0006] In this embodiment, by comparing the inlet pipe temperature with a suitable temperature threshold, it can be identified whether the indoor unit meets the cooling requirements, thereby either closing the expansion valve or adjusting it to the minimum opening, thus reducing energy consumption and improving system reliability.

[0007] Optionally, controlling the opening degree of the expansion valve to switch between minimum opening degree and closed includes: if the inlet pipe temperature is greater than the user-set temperature, then controlling the opening degree of the expansion valve to the minimum opening degree; if the inlet pipe temperature is less than or equal to the user-set temperature, then controlling the expansion valve to close.

[0008] In this embodiment, if the inlet pipe temperature is greater than the user-set temperature, the opening of the expansion valve is controlled to the minimum opening; if the inlet pipe temperature is less than or equal to the user-set temperature, the expansion valve is controlled to close, and the refrigerant that has not been completely evaporated in the indoor unit is evaporated by heat exchange through ventilation. Based on the above control logic, the refrigerant can be evaporated as completely as possible, taking into account both energy saving and preventing liquid return.

[0009] Optionally, the indoor unit energy-saving control process further includes: when the user-set temperature is less than or equal to the suitable temperature threshold and the indoor ambient temperature is greater than the suitable temperature threshold, if the current fan speed of the indoor unit is at its maximum, then searching for other indoor units that meet the control conditions; the control conditions are that the indoor unit is in cooling operation mode and the ambient temperature of the space is greater than the suitable temperature threshold; if there are other indoor units that meet the control conditions, and the current fan speed of the other indoor unit is not at its maximum, then increasing the current fan speed of the other indoor unit by at least one level; if there are other indoor units that meet the control conditions, and the current fan speed of the other indoor unit is at its maximum, then halving the cooling demand of the indoor unit.

[0010] In this embodiment, other indoor units that meet the control conditions can be found so that excess refrigerant can be allocated to other indoor units with higher demand.

[0011] Optionally, the indoor unit energy-saving control process further includes: if there are no other indoor units that meet the control conditions, then the cooling demand of the indoor unit is set to zero.

[0012] In this embodiment, if there are no other indoor units that meet the above control conditions, the cooling demand of the current indoor unit is set to zero, the outdoor unit output is reduced, the evaporation temperature is increased, and liquid return is avoided.

[0013] Optionally, the indoor unit energy-saving control process further includes: if there are other indoor units that meet the control conditions, and the current fan speed of the other indoor units is not the maximum fan speed, then increase the refrigerant distribution of the other indoor units.

[0014] In this embodiment, excess refrigerant is allocated to other indoor units with higher demand, thereby reducing energy consumption and improving system reliability.

[0015] Optionally, the multi-split air conditioning system includes multiple indoor units. Before obtaining the expansion valve opening degree, inlet pipe temperature and outlet pipe temperature of the indoor units, the method further includes: obtaining the number of indoor units that are turned on. If the number of indoor units that are turned on is greater than one, the step of obtaining the expansion valve opening degree, inlet pipe temperature and outlet pipe temperature of the indoor units is continued.

[0016] In this embodiment, before executing the above method, it is necessary to determine the number of indoor units that are in the open state. If multiple indoor units are open, the steps of the above method can continue to be executed, thereby avoiding liquid return, reducing energy consumption, and improving system reliability.

[0017] This invention provides an energy-saving control device for the indoor units of a multi-split air conditioning system. The device includes: an acquisition module, used to acquire the expansion valve opening, inlet pipe temperature, and outlet pipe temperature of each indoor unit when multiple indoor units are on during cooling operation; and an energy-saving control module, used to control the indoor unit to execute an energy-saving control process if the expansion valve opening of an indoor unit is at its minimum and the inlet pipe temperature is greater than or equal to the outlet pipe temperature. The energy-saving control process includes: reducing the outdoor unit's cooling output level when the user-set temperature is greater than a suitable temperature threshold; and reducing the outdoor unit's cooling output level when the user-set temperature is less than a suitable temperature threshold. If the indoor ambient temperature is less than or equal to the suitable temperature threshold and the indoor ambient temperature is greater than the user-set temperature and the difference is greater than the temperature difference threshold, the opening of the expansion valve is controlled to switch between minimum opening and closed. If the indoor ambient temperature is greater than the user-set temperature and the difference is less than or equal to the temperature difference threshold, the expansion valve is controlled to close. If the indoor ambient temperature is less than or equal to the suitable temperature threshold and the indoor ambient temperature is greater than the suitable temperature threshold, and the current fan speed of the indoor unit is not the maximum fan speed, the current fan speed is increased by at least one level.

[0018] This invention provides a multi-split air conditioner, including a computer-readable storage medium storing a computer program and a processor, wherein the computer program is read and executed by the processor to implement the above-described method.

[0019] This invention provides a computer-readable storage medium storing a computer program, which is read and executed by a processor to implement the above-described method.

[0020] The indoor unit energy-saving control device and multi-split air conditioner of the present invention can achieve the same technical effect as the indoor unit energy-saving control method of the above-mentioned multi-split system. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structure of a multi-unit air conditioning system according to an embodiment of the present invention;

[0022] Figure 2 This is a flowchart illustrating the energy-saving control method for the indoor unit of a multi-split air conditioning system in an embodiment of the present invention.

[0023] Figure 3 This is a schematic flowchart illustrating the entry conditions of the control program for the indoor unit energy-saving control method in an embodiment of the present invention.

[0024] Figure 4 This is a schematic flowchart illustrating the adjustment and control process of the indoor unit energy-saving control method of a multi-split air conditioning system in an embodiment of the present invention;

[0025] Figure 5 This is a schematic diagram of the structure of an indoor unit energy-saving control device for a multi-split air conditioning system according to an embodiment of the present invention. Detailed Implementation

[0026] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0027] This invention provides an energy-saving control method for the indoor unit of a multi-split air conditioning system to solve the problem of adjustment failure during the cooling operation of existing multi-split indoor units, thereby reducing energy consumption, improving user comfort, and reducing system reliability risks.

[0028] When a multi-split air conditioning system is operating in cooling mode, the pipe temperature and expansion valve position of the indoor unit are monitored and compared to determine the valve adjustment status and whether energy-saving adjustments are needed. Based on the indoor unit's operating requirements, the opening and closing of the expansion valve and the fan speed are controlled to maximize heat exchange, ensure complete refrigerant evaporation, reduce energy consumption, and guarantee user comfort and system reliability.

[0029] Figure 1 A schematic diagram of a multi-split air conditioning system according to an embodiment of the present invention is shown. Figure 1The diagram shows outdoor unit 10, indoor unit 1, indoor unit 2 to indoor unit n. Outdoor unit 10 includes a compressor 11, oil separator 12, vapor separator 13, four-way valve 14, fan 15, liquid pipe shut-off valve 16, and gas pipe shut-off valve 17. Indoor unit 1 includes an outlet pipe temperature sensor 101, a middle pipe temperature sensor 102, an inlet pipe temperature sensor 103, an ambient temperature sensor 104, a fan 105, and an electronic expansion valve 106. Indoor unit 2 includes an outlet pipe temperature sensor 201, a middle pipe temperature sensor 202, an inlet pipe temperature sensor 203, an ambient temperature sensor 204, a fan 205, and an electronic expansion valve 206. Each indoor unit is equipped with an independent electronic expansion valve.

[0030] Figure 2 A schematic flowchart of an indoor unit energy-saving control method for a multi-split air conditioning system according to an embodiment of the present invention is shown. The method includes the following steps:

[0031] S22: If multiple indoor units are on during cooling operation, the expansion valve opening, inlet pipe temperature, and outlet pipe temperature of each indoor unit are obtained. First, the number of indoor units on in the multi-split system is determined. If more than one indoor unit is on, subsequent steps are executed. The inlet pipe temperature represents the temperature of the refrigerant before it enters the coil, and the outlet pipe temperature represents the temperature of the refrigerant after it leaves the coil.

[0032] S24. If the expansion valve of the indoor unit is at its minimum opening and the inlet pipe temperature is greater than or equal to the outlet pipe temperature, then control the indoor unit to execute the indoor unit energy-saving control process.

[0033] The expansion valve of the indoor unit can be adjusted by controlling its opening degree; the smaller the opening, the smaller the refrigerant flow. Typically, the expansion valve has a minimum opening degree that allows refrigerant to pass through. If the valve is already at its minimum opening and further reduction in flow is needed, it can be closed.

[0034] If the expansion valve is at its minimum opening, but the inlet pipe temperature is greater than or equal to the outlet pipe temperature, it indicates that the expansion valve has lost its control effect. There is excessive refrigerant in the indoor unit, which has not fully evaporated, posing a risk of liquid return. In this situation, the system will enter energy-saving control mode and execute the indoor unit's energy-saving control procedure. This procedure includes the following steps.

[0035] (1) If the user-set temperature is higher than the appropriate temperature threshold, the outdoor unit's cooling output level will be reduced.

[0036] The suitable temperature threshold can be a temperature that feels comfortable to the human body, for example, set to around 26℃. If the user sets a temperature higher than this suitable temperature threshold, it indicates that the user's current cooling demand is not high. In this case, there is a risk of incomplete refrigerant evaporation leading to liquid return from the indoor unit. Therefore, the current cooling demand of the indoor unit can be ignored, reducing the cooling output of the outdoor unit to achieve energy saving.

[0037] (2) When the user-set temperature is less than or equal to the suitable temperature threshold and the indoor ambient temperature is less than or equal to the suitable temperature threshold, if the indoor ambient temperature is greater than the user-set temperature and the difference is greater than the temperature difference threshold, the opening degree of the expansion valve is controlled to switch between minimum opening degree and closed. If the indoor ambient temperature is greater than the user-set temperature and the difference is less than or equal to the temperature difference threshold, the expansion valve is controlled to close.

[0038] If the user sets a temperature less than or equal to the above-mentioned suitable temperature threshold, and the indoor ambient temperature is less than or equal to the suitable temperature threshold, it means that the current environment can meet the user's basic temperature requirements. The temperature needs to be adjusted according to the difference between the user's actual set temperature and the indoor ambient temperature, as follows.

[0039] If the indoor ambient temperature is higher than the user-set temperature and the difference between the two exceeds the temperature difference threshold, the expansion valve opening is switched between minimum opening and closed. This means that a certain amount of cooling capacity is still required under current conditions, and the expansion valve can be controlled to intermittently supply refrigerant. Specifically, this can be divided into two cases: the inlet pipe temperature is higher than the user-set temperature, and the inlet pipe temperature is less than or equal to the user-set temperature. If the inlet pipe temperature is higher than the user-set temperature, cooling capacity is considered required, and the expansion valve opening can be controlled to the minimum. If the inlet pipe temperature is less than or equal to the user-set temperature, the expansion valve can be closed, allowing ventilation to evaporate any incompletely evaporated refrigerant in the indoor unit. Based on this control logic, refrigerant evaporation can be maximized, balancing energy saving and preventing liquid return.

[0040] If the indoor ambient temperature is higher than the user-set temperature and the difference between the two is less than or equal to the aforementioned temperature difference threshold, the expansion valve will be closed. When the temperature difference is small, the heat exchange is reduced, making liquid return more likely. In this case, the expansion valve can be completely closed, and ventilation only should be provided.

[0041] (3) If the user-set temperature is less than or equal to the suitable temperature threshold and the indoor ambient temperature is greater than the suitable temperature threshold, the current fan speed of the indoor unit will be increased by at least one level if the current fan speed is not the maximum fan speed.

[0042] If the user sets a temperature less than or equal to the suitable temperature threshold, but the indoor ambient temperature is greater than that threshold, it indicates that the current environment does not meet basic comfort requirements. Therefore, it is necessary to maximize heat exchange to meet the indoor unit's cooling needs. Specifically, this can be achieved by increasing the indoor unit's fan speed to increase airflow, enhance heat exchange, and prevent liquid backflow.

[0043] The indoor unit energy-saving control method for multi-split air conditioning systems provided in this invention can determine the refrigerant evaporation status by measuring the expansion valve opening, the inlet pipe temperature, and the outlet pipe temperature of the indoor unit. If the refrigerant is not completely evaporated and there is a risk of liquid return, the indoor unit energy-saving control process is executed. By adjusting the expansion valve opening and the indoor unit fan speed, the refrigerant can be made to evaporate as completely as possible, achieve the desired cooling effect, avoid the risk of liquid return, reduce energy consumption, improve system reliability, and take into account user comfort.

[0044] Furthermore, the above-mentioned indoor unit energy-saving control process also includes the following steps:

[0045] If the user-set temperature is higher than the aforementioned suitable temperature threshold, but the inlet pipe temperature is lower than the suitable temperature threshold, the expansion valve will be closed. At this time, the indoor unit's heat exchange can still meet comfort requirements. With the indoor unit's expansion valve closed, heat exchange can occur solely through ventilation, and the indoor unit's pipe temperature will gradually increase.

[0046] If the inlet pipe temperature is greater than or equal to the aforementioned suitable temperature threshold, the expansion valve opening will be set to its minimum. In this case, the indoor unit needs to provide more refrigerant for cooling, so the expansion valve opening can be adjusted to its minimum to reduce the outlet air temperature.

[0047] By comparing the inlet pipe temperature with a suitable temperature threshold, it can be determined whether the indoor unit meets the cooling requirements, and then either close the expansion valve or adjust it to the minimum opening, thereby reducing energy consumption and improving system reliability.

[0048] Furthermore, considering that the current fan speed of the indoor unit may already be at its maximum, making it impossible to further increase heat exchange by increasing the airflow, other indoor units in the multi-split system that meet preset conditions can be identified. By supplying these other indoor units with more refrigerant or controlling them to exchange heat more efficiently, liquid return can be avoided. Based on this, the above-mentioned indoor unit energy-saving control process can also include:

[0049] If the user-set temperature is less than or equal to the suitable temperature threshold and the indoor ambient temperature is greater than the suitable temperature threshold, and the current fan speed of the indoor unit is at its maximum, the system will search for other indoor units that meet the control conditions. These conditions are: the unit is in cooling mode and the ambient temperature of the room is greater than the suitable temperature threshold. The system will then search for other indoor units that meet these conditions to allocate excess refrigerant to units with higher demand.

[0050] If there are other indoor units that meet the control conditions, and the current fan speed of the other indoor units is not the maximum fan speed, then increase the current fan speed of the other indoor units by at least one level.

[0051] If other indoor units meet the control conditions and their current fan speed is at maximum, then the cooling demand of the indoor unit will be halved. If other indoor units are also at their highest fan speed and their heat exchange capacity has reached its limit, then the cooling demand of the liquid return indoor unit can be adjusted to half of its original demand, reducing the outdoor unit's output, increasing the evaporation temperature, and preventing liquid return.

[0052] Furthermore, if other indoor units meet the control conditions, and their current fan speed is not at maximum, then the refrigerant distribution to these other indoor units will be increased. By increasing the refrigerant distribution to these other indoor units, refrigerant return to the current indoor unit will be avoided.

[0053] If no other indoor unit meets the control conditions, the cooling demand of the aforementioned indoor unit will be set to zero. If no other indoor unit meets the control conditions, the cooling demand of the current indoor unit will be set to zero, the outdoor unit output will be reduced, the evaporation temperature will be increased, and liquid return will be avoided.

[0054] A multi-split air conditioning system includes multiple indoor units. Before executing the above method, it is necessary to determine the number of indoor units that are currently active. If multiple indoor units are active, the steps of the above method can continue to be executed. Therefore, before S22, the method may further include: obtaining the number of active indoor units; if the number is greater than one, then continuing with the steps of obtaining the expansion valve opening, inlet pipe temperature, and outlet pipe temperature of the indoor units. When multiple indoor units are active, the address of each indoor unit can also be obtained.

[0055] Figure 3 A schematic flowchart illustrating the control procedure entry conditions of the indoor unit energy-saving control method for a multi-split air conditioning system according to an embodiment of the present invention is shown. The control procedure entry conditions include the following steps:

[0056] S301, multi-split system in cooling operation.

[0057] The multi-split system operates in cooling mode, and the system is stable when the time reaches t0 (which can be set to 20-30 minutes).

[0058] S302: Determine if the number of powered-on internal units is greater than 1. If yes, proceed to S303; otherwise, end the process.

[0059] If more than one internal unit is turned on, obtain the address n of the internal unit that is turned on.

[0060] S303, Determine if the indoor unit meets the current valve opening degree P when it is turned on. n Minimum opening P has been reached nm And the inlet pipe temperature T jn greater than the outlet tube temperature T cn If yes, then execute S304; otherwise, return to execute S302.

[0061] Detect the opening degree Pn of each indoor unit valve. If the current valve opening Pn has reached the minimum opening Pnm, i.e., Pn = Pnm, then detect and compare the indoor unit pipe temperature. If the inlet pipe temperature Tjn of indoor unit n is greater than the outlet pipe temperature Tcn, i.e., Tjn > Tcn, it can be considered that the expansion valve of indoor unit n has lost its control effect, the indoor unit has too much refrigerant, and it has not been completely evaporated, posing a risk of liquid return. It is determined that the indoor unit has entered the adjustment control mode.

[0062] S304, enter the control procedure.

[0063] After the adjustment is completed, the adjustment conditions are judged at intervals of t1 (t1 is recommended to be 5-10 minutes). If oil return, start-up or shutdown occurs during the process, the adjustment content becomes invalid, the internal machine of the system runs according to the settings, and the adjustment is judged again after the running time t0.

[0064] Figure 4 A schematic flowchart of the adjustment and control process of the indoor unit energy-saving control method of a multi-split air conditioning system according to an embodiment of the present invention is shown. The adjustment and control process includes the following steps:

[0065] S401, obtain the address i of the indoor unit to be adjusted and the current operating parameters. The operating parameters include: inner loop temperature Tai, inlet pipe temperature Tji, outlet pipe temperature Tci, set temperature Tsi, current set operating fan speed Fsi, and expansion valve opening Pi.

[0066] S402, determine whether the set temperature Tsi is greater than the suitable temperature threshold of 26℃. If yes, proceed to S403; otherwise, proceed to S407.

[0067] If the set temperature Tsi is higher than 26℃, the cooling demand can be considered low, the refrigerant heat exchange is low, and the refrigerant evaporation is incomplete, resulting in liquid return from the indoor unit. In this case, the current indoor unit cooling demand can be ignored, and the target output of the outdoor unit will be reduced.

[0068] S403, based on the current indoor unit requirements.

[0069] S404: Determine if the inlet pipe temperature Tji is greater than 26℃. If yes, proceed to S405; otherwise, proceed to S406.

[0070] S405 controls Pi = Pim. If the inlet pipe temperature Tji is below 26℃, the indoor unit's heat exchange temperature can still be below 26℃ to meet comfort requirements. In this case, the indoor unit valve can be closed, the fan can ventilate and exchange heat, and the indoor unit's pipe temperature will gradually increase.

[0071] S406, control Pi = 0. If the pipe temperature is higher than 26℃, the indoor unit valve is at its minimum opening Pim, providing refrigerant to reduce the outlet air temperature.

[0072] S407, determine if the inner ring temperature Tai is less than 26℃. If yes, proceed to S408; otherwise, proceed to S410.

[0073] If the set temperature Tsi is below 26℃ and the inner ring temperature Tai is below 26℃, the ambient temperature can be considered to meet basic comfort requirements. Subsequent cooling needs can be adjusted based on the temperature difference.

[0074] S408, determine whether the ambient temperature Tai is greater than the set temperature Tsi+A. If yes, proceed to S409; otherwise, proceed to S406.

[0075] If the ambient temperature Tai is higher than the set temperature Tsi, exceeding A (recommended 4-6), it is determined that a certain amount of cooling capacity is still needed. In this case, the valve can be controlled to intermittently supply refrigerant. When the ambient temperature is close to the set temperature, the temperature difference is small, the heat exchange is reduced, and liquid return is more likely to occur. It is considered that the heat exchange demand is small at this time, and the indoor unit valve can be completely closed, with only ventilation.

[0076] S409, determine whether the inlet pipe temperature Tji is greater than the set temperature Tsi. If yes, proceed to S405; otherwise, proceed to S406.

[0077] When the inlet pipe temperature is higher than the set temperature, it is assumed that cooling capacity is required, and the valve step is kept at the minimum Pim; otherwise, the valve can be closed, and ventilation can be used to evaporate any refrigerant that has not been completely evaporated in the indoor unit.

[0078] S410, determine if the indoor unit fan speed Fi is the maximum fan speed Fdi. If yes, proceed to S411; otherwise, proceed to S412.

[0079] If the set temperature Tsi is below 26℃ and the inner ring temperature Tai is above 26℃, the ambient temperature is considered not to meet basic comfort requirements. It is necessary to maximize heat exchange to meet the cooling needs of the indoor units, or to allocate excess refrigerant to other indoor units with higher cooling demands.

[0080] When the indoor unit's fan speed Fi is not the maximum speed Fdi, consider increasing the airflow to enhance heat exchange and raise the outlet pipe temperature, thus preventing liquid backflow. Increase the fan speed to the next higher setting, i.e., Fi = Fi + 1.

[0081] S411, determine if the ambient temperature Tai of other indoor units is 26℃. If yes, proceed to S413; otherwise, proceed to S414.

[0082] If the current indoor unit i is already at its maximum fan speed and cannot increase the heat exchange of the current indoor unit, then find another indoor unit n with an ambient temperature higher than 26°C and prioritize providing more refrigerant to achieve sufficient heat exchange.

[0083] If the ambient temperature of the other indoor units without liquid return is below 26℃, then the other indoor units also do not have much cooling demand. The system output can be reduced by setting the cooling demand of the indoor unit that needs to be adjusted to 0, reducing the compressor output, increasing the evaporation temperature, and avoiding liquid return.

[0084] S412, the current indoor unit's fan speed is increased to the next higher setting.

[0085] S413, determine if the fan speed of other indoor units is at the maximum. If yes, proceed to S415; otherwise, proceed to S416.

[0086] S414, assume the internal unit i requirement is 0.

[0087] S415, assuming the internal unit i requirement is 1 / 2.

[0088] S416, the fan speed of other indoor units is increased to the next higher setting than the current setting.

[0089] If the ambient temperature is higher than 26℃ and the indoor unit is not at its highest fan speed, the fan speed can be increased to enhance heat exchange and distribute more refrigerant. If the fan speed is already at its highest and the heat exchange capacity has reached its limit, the cooling demand of the indoor unit that is experiencing liquid return can be adjusted to half of its original demand. This reduces the output of the outdoor unit, increases the evaporation temperature, and prevents liquid return.

[0090] This invention, through adjustments to indoor unit valves and fans, aims to maximize refrigerant evaporation, prevent liquid return, reduce energy consumption, improve system reliability, and enhance user comfort. Specifically, the refrigerant evaporation status is assessed using indoor unit pipe temperature and valve position data. Then, based on ambient temperature and set temperature, the adjustment method is determined to ensure the refrigerant evaporates as completely as possible, achieving the desired cooling effect.

[0091] Figure 5 This invention illustrates a structural schematic diagram of an indoor unit energy-saving control device for a multi-split air conditioning system according to an embodiment of the present invention. The device includes:

[0092] The acquisition module 501 is used to acquire the expansion valve opening degree, inlet pipe temperature and outlet pipe temperature of each indoor unit when multiple indoor units are turned on during refrigeration operation.

[0093] Energy-saving control module 502 is used to control the indoor unit to execute an indoor unit energy-saving control process if the expansion valve opening of the indoor unit is at its minimum opening and the inlet pipe temperature is greater than or equal to the outlet pipe temperature; the indoor unit energy-saving control process includes:

[0094] If the user-set temperature is higher than the suitable temperature threshold, the outdoor unit's cooling output level will be reduced.

[0095] If the user-set temperature is less than or equal to the suitable temperature threshold and the indoor ambient temperature is less than or equal to the suitable temperature threshold, and if the indoor ambient temperature is greater than the user-set temperature and the difference is greater than the temperature difference threshold, the opening degree of the expansion valve is controlled to switch between minimum opening and closed; if the indoor ambient temperature is greater than the user-set temperature and the difference is less than or equal to the temperature difference threshold, the expansion valve is controlled to close.

[0096] If the user-set temperature is less than or equal to the suitable temperature threshold and the indoor ambient temperature is greater than the suitable temperature threshold, and the current fan speed of the indoor unit is not the maximum fan speed, then the current fan speed will be increased by at least one level.

[0097] The indoor unit energy-saving control device of the multi-split air conditioning system provided in this invention can determine the refrigerant evaporation status by the expansion valve opening, the inlet pipe temperature and the outlet pipe temperature of the indoor unit. If there is a risk of liquid return due to incomplete evaporation, the indoor unit energy-saving control process is executed. By adjusting the opening of the expansion valve and the indoor unit fan speed, the refrigerant can be made to evaporate as completely as possible, exert the due cooling effect, avoid the risk of liquid return, reduce energy consumption, improve system reliability, and take into account user comfort.

[0098] As a feasible approach, the energy-saving control module is also used to: if the inlet pipe temperature is less than the suitable temperature threshold when the user-set temperature is greater than the suitable temperature threshold, control the expansion valve to close; if the inlet pipe temperature is greater than or equal to the suitable temperature threshold, control the opening degree of the expansion valve to the minimum opening degree.

[0099] As a feasible approach, the energy-saving control module is also used to: control the opening degree of the expansion valve to the minimum opening degree if the inlet pipe temperature is greater than the user-set temperature; and control the expansion valve to close if the inlet pipe temperature is less than or equal to the user-set temperature.

[0100] As a feasible approach, the energy-saving control module is further configured to: when the user-set temperature is less than or equal to the suitable temperature threshold and the indoor ambient temperature is greater than the suitable temperature threshold, if the current fan speed of the indoor unit is at its maximum, then search for other indoor units that meet the control conditions; the control conditions are that the unit is in cooling operation mode and the ambient temperature of the space is greater than the suitable temperature threshold; if there are other indoor units that meet the control conditions, and the current fan speed of the other indoor unit is not at its maximum, then increase the current fan speed of the other indoor unit by at least one level; if there are other indoor units that meet the control conditions, and the current fan speed of the other indoor unit is at its maximum, then halve the cooling demand of the indoor unit.

[0101] As a feasible approach, the energy-saving control module is also used to: set the cooling demand of the indoor unit to zero if there are no other indoor units that meet the control conditions.

[0102] As a feasible approach, the energy-saving control module is also used to: if there are other indoor units that meet the control conditions, and the current fan speed of the other indoor units is not the maximum fan speed, then increase the refrigerant distribution of the other indoor units.

[0103] As a feasible approach, the multi-split air conditioning system includes multiple indoor units, and the energy-saving control module is further used to: obtain the number of indoor units that are turned on; if the number of indoor units that are turned on is greater than one, then continue to execute the steps of obtaining the expansion valve opening degree, inlet pipe temperature and outlet pipe temperature of the indoor units.

[0104] This invention also provides a multi-split air conditioner, including a computer-readable storage medium storing a computer program and a processor, wherein the computer program is read and executed by the processor to implement the above-described method.

[0105] This invention also provides a computer-readable storage medium storing a computer program. When the computer program is read and executed by a processor, it implements the method provided in the above embodiments and achieves the same technical effect. To avoid repetition, further details are omitted here. The computer-readable storage medium may be a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk.

[0106] Of course, those skilled in the art will understand that all or part of the processes in the above embodiments can be implemented by computer-controlled devices. The program can be stored in a computer-readable storage medium. When the program is executed, it can include the processes of the above method embodiments. The storage medium can be a memory, a disk, an optical disk, etc.

[0107] While the present invention has been disclosed above, it is not limited thereto. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

[0108] Finally, it should be noted that in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0109] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0110] While the present invention has been disclosed above, it is not limited thereto. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A method for energy-saving control of the indoor unit of a multi-split air conditioning system, characterized in that, The method includes: If multiple indoor units are turned on during refrigeration operation, the expansion valve opening, inlet pipe temperature, and outlet pipe temperature of each indoor unit are obtained. If the expansion valve of the indoor unit is at its minimum opening and the inlet pipe temperature is greater than or equal to the outlet pipe temperature, then the indoor unit is controlled to execute the indoor unit energy-saving control process; the indoor unit energy-saving control process includes: If the user-set temperature is higher than the suitable temperature threshold, the outdoor unit's cooling output level will be reduced. If the user-set temperature is less than or equal to the suitable temperature threshold and the indoor ambient temperature is less than or equal to the suitable temperature threshold, and if the indoor ambient temperature is greater than the user-set temperature and the difference is greater than the temperature difference threshold, the opening degree of the expansion valve is controlled to switch between minimum opening and closed; if the indoor ambient temperature is greater than the user-set temperature and the difference is less than or equal to the temperature difference threshold, the expansion valve is controlled to close. If the user-set temperature is less than or equal to the suitable temperature threshold and the indoor ambient temperature is greater than the suitable temperature threshold, and the current fan speed of the indoor unit is not the maximum fan speed, then the current fan speed will be increased by at least one level.

2. The method as described in claim 1, characterized in that, The indoor unit energy-saving control process also includes: If the user-set temperature is greater than the suitable temperature threshold, but the inlet pipe temperature is less than the suitable temperature threshold, then the expansion valve is controlled to close. If the inlet pipe temperature is greater than or equal to the suitable temperature threshold, the opening degree of the expansion valve is controlled to the minimum opening degree.

3. The method as described in claim 1, characterized in that, The control of the expansion valve opening degree switching between minimum opening and closed includes: If the inlet pipe temperature is greater than the user-set temperature, then the opening degree of the expansion valve is controlled to the minimum opening degree; If the inlet pipe temperature is less than or equal to the user-set temperature, then the expansion valve is controlled to close.

4. The method as described in claim 1, characterized in that, The indoor unit energy-saving control process also includes: If the user-set temperature is less than or equal to the suitable temperature threshold and the indoor ambient temperature is greater than the suitable temperature threshold, and the current fan speed of the indoor unit is at the maximum fan speed, then other indoor units that meet the control conditions will be searched; the control conditions are that the unit is in cooling mode and the indoor ambient temperature of the space is greater than the suitable temperature threshold. If there are other indoor units that meet the control conditions, and the current fan speed of the other indoor unit is not the maximum fan speed, then the current fan speed of the other indoor unit will be increased by at least one level. If there are other indoor units that meet the control conditions, and the current fan speed of the other indoor unit is at the maximum fan speed, then the cooling demand of the other indoor unit will be halved.

5. The method as described in claim 4, characterized in that, The indoor unit energy-saving control process also includes: If no other indoor unit meets the control conditions, the cooling demand of the indoor unit will be set to zero.

6. The method as described in claim 4, characterized in that, The indoor unit energy-saving control process also includes: If there are other indoor units that meet the control conditions, and the current fan speed of the other indoor unit is not the maximum fan speed, then increase the refrigerant distribution of the other indoor unit.

7. An energy-saving control device for the indoor unit of a multi-split air conditioning system, characterized in that, The device includes: The acquisition module is used to acquire the expansion valve opening degree, inlet pipe temperature and outlet pipe temperature of each indoor unit when multiple indoor units are turned on during refrigeration operation. An energy-saving control module is used to control the indoor unit to execute an energy-saving control process if the expansion valve of the indoor unit is at its minimum opening and the inlet pipe temperature is greater than or equal to the outlet pipe temperature; the energy-saving control process includes: If the user-set temperature is higher than the suitable temperature threshold, the outdoor unit's cooling output level will be reduced. If the user-set temperature is less than or equal to the suitable temperature threshold and the indoor ambient temperature is less than or equal to the suitable temperature threshold, and if the indoor ambient temperature is greater than the user-set temperature and the difference is greater than the temperature difference threshold, the opening degree of the expansion valve is controlled to switch between minimum opening and closed; if the indoor ambient temperature is greater than the user-set temperature and the difference is less than or equal to the temperature difference threshold, the expansion valve is controlled to close. If the user-set temperature is less than or equal to the suitable temperature threshold and the indoor ambient temperature is greater than the suitable temperature threshold, and the current fan speed of the indoor unit is not the maximum fan speed, then the current fan speed will be increased by at least one level.

8. A multi-split air conditioner, characterized in that, The method includes a computer-readable storage medium storing a computer program, which is read and executed by the processor to implement the method as described in any one of claims 1-6.

9. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that, when read and executed by a processor, implements the method as described in any one of claims 1-6.

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