Refrigerant recovery control method for multi-split air conditioner and multi-split air conditioner

Abstract

The invention relates to the technical field of air conditioners, particularly provides a refrigerant recovery control method for a multi-split air conditioner and the multi-split air conditioner, and aims to solve the problems of incomplete recovery and low efficiency in refrigerant recovery. In order to achieve the purpose, the control method comprises the steps that when a refrigerant recovery instruction is received, at least one outdoor unit receiving a refrigerant is determined as a target unit; controlling the multi-split air conditioner to operate in a refrigeration mode and operate according to a preset operation state so as to stabilize the operation states of the indoor unit and the outdoor unit; closing a cut-off valve on a liquid pipe corresponding to the target machine so as to prevent the refrigerant from flowing out of the target machine; timing is started, and at least one parameter of the target machine is monitored to judge whether refrigerant recovery is completed or not; and when it is judged that refrigerant recovery is completed, a block valve on the low-pressure air pipe corresponding to the target machine is closed. By controlling the block valves on the pipelines, the refrigerant is guided to migrate to the target machine, the recovery state is monitored in real time, it is ensured that the refrigerant is completely recovered, and the recovery efficiency is improved.

Description

Technical Field

[0001] This invention relates to the field of air conditioning technology, specifically providing a refrigerant recovery control method for multi-split air conditioners and a multi-split air conditioner. Background Technology

[0002] In the field of multi-split air conditioning technology, a system typically consists of multiple indoor units and multiple outdoor units connected by complex refrigerant piping to achieve flexible cooling and heating functions. When the system has been in operation for a long time or malfunctions and requires maintenance and repair, it is often necessary to recover the refrigerant in the piping.

[0003] Currently, conventional refrigerant recovery operations heavily rely on external dedicated recovery pumps, refrigerant tanks, and other equipment. This process is not only cumbersome, requiring professional personnel to connect pipelines, operate equipment, and closely monitor it, but it is also time-consuming. For large multi-split systems, with their complex piping networks and large total charge volumes, external recovery is even less efficient, potentially leading to refrigerant residue or incomplete recovery, affecting the safety and quality of subsequent maintenance work. Furthermore, external equipment itself presents risks such as inconvenience in portability, interface compatibility issues, and the potential introduction of impurities or air during operation.

[0004] Especially for large multi-split systems, the extensive piping network and the potential for indoor and outdoor units to operate in different modes (such as partial cooling, partial heating, or simultaneous operation) further complicate the complete and efficient recovery of refrigerant. In current technological practices, safely and quickly collecting the refrigerant distributed throughout the system to a designated location (such as a specific outdoor unit or storage container) without relying on complex external devices remains a pressing engineering challenge.

[0005] Therefore, a new technical solution is needed in this field to solve the above problems. Summary of the Invention

[0006] The present invention aims to solve the above-mentioned technical problems, namely, to solve the problems of incomplete recovery and low efficiency of refrigerant recovery in existing multi-split air conditioners.

[0007] In a first aspect, the present invention provides a refrigerant recovery control method for a multi-split air conditioner, the multi-split air conditioner comprising multiple indoor units and multiple outdoor units connected in parallel, wherein each of the indoor units has a high-pressure gas pipe, a low-pressure gas pipe, and a liquid pipe, and each of the outdoor units has a high-pressure gas pipe, a low-pressure gas pipe, and a liquid pipe, each equipped with an independently shut-off valve; the control method includes: S100: When a refrigerant recovery command is received, at least one of the outdoor units that receive the refrigerant is identified as the target unit; S200: Control the multi-split air conditioner to operate in cooling mode and according to preset operating status, so as to stabilize the operating status of the indoor unit and the outdoor unit; S300: Close the shut-off valve on the liquid line corresponding to the target unit to block the refrigerant from flowing out of the target unit but allow the refrigerant to enter the target unit; S400: Start timing and monitor at least one parameter of the target unit to determine whether the refrigerant recovery is complete; S500: When it is determined that the refrigerant recovery is complete, close the shut-off valve on the low-pressure gas pipe corresponding to the target unit.

[0008] In the preferred embodiment of the above-mentioned refrigerant recovery control method for multi-split air conditioning, in step S400, the at least one parameter includes the pressure value of the low-pressure side of the target unit.

[0009] In the preferred embodiment of the above-mentioned refrigerant recovery control method for multi-split air conditioning systems, step S400 specifically includes: Obtain the duration of refrigerant recovery; Monitor the pressure value on the low-pressure side; The recovery duration and the pressure value on the low-pressure side are used to determine whether the refrigerant recovery is complete.

[0010] In the preferred technical solution of the above-mentioned refrigerant recovery control method for multi-split air conditioners, the step of "determining whether the refrigerant recovery is complete based on the recovery duration and the pressure value on the low-pressure side" specifically includes: When the recovery duration reaches the first preset duration or when the pressure value on the low-pressure side is less than or equal to the preset pressure value, the refrigerant recovery is determined to be complete. When the refrigerant recovery duration reaches a first preset duration and the pressure value on the low-pressure side is greater than the preset pressure value, a refrigerant recovery abnormal signal is generated.

[0011] In the preferred embodiment of the above-mentioned refrigerant recovery control method for multi-split air conditioners, the multi-split air conditioner further includes an external receiving device, which is connected to the target unit via a pipeline, and a valve is installed on the pipeline. The control method further includes: S600: Open the valve to transfer the refrigerant in the target unit to the external receiving device; S700: Detect the amount of refrigerant in the target unit; S800: When the amount of refrigerant in the target unit is lower than the preset amount of refrigerant, close the valve.

[0012] In the preferred embodiment of the above-mentioned refrigerant recovery control method for multi-split air conditioning, the external receiving device is a pressure vessel.

[0013] In the preferred embodiment of the above-mentioned refrigerant recovery control method for multi-split air conditioners, when the multi-split air conditioner is currently in heating mode or simultaneously in cooling and heating mode, step S200 specifically includes: Control the multi-split air conditioner to switch the heating mode or the simultaneous cooling and heating mode to the cooling mode; The multi-split air conditioner is made to operate according to the preset operating state.

[0014] In the preferred technical solution of the above-mentioned multi-split air conditioner refrigerant recovery control method, "making the multi-split air conditioner operate according to a preset operating state" specifically includes: The compressors and electronic expansion valves of all outdoor units are operated at a preset frequency and a first preset opening degree, respectively. The electronic expansion valves and fans of all the indoor units are set to the second preset opening degree and preset speed, respectively.

[0015] In the preferred technical solution of the above-mentioned refrigerant recovery control method for multi-split air conditioners, "making the multi-split air conditioner operate according to a preset operating state" specifically includes: The multi-split air conditioner is then operated for a second period of time according to a preset operating state.

[0016] In a second aspect, the present invention also provides a multi-split air conditioner, including a controller configured to perform the control method described in any of the preceding claims.

[0017] Those skilled in the art will understand that the technical solution of the present invention provides a refrigerant recovery control method for a multi-split air conditioner. The multi-split air conditioner includes multiple indoor units and multiple outdoor units connected in parallel. Each indoor unit has a high-pressure gas pipe, a low-pressure gas pipe, and a liquid pipe, and each outdoor unit has a high-pressure gas pipe, a low-pressure gas pipe, and a liquid pipe, each equipped with an independently shut-off valve. The control method includes: S100: When a refrigerant recovery command is received, at least one outdoor unit receiving refrigerant is identified as the target unit; S200: The multi-split air conditioner is controlled to operate in cooling mode and according to a preset operating state to stabilize the operating state of the indoor and outdoor units; S300: The shut-off valve on the liquid pipe corresponding to the target unit is closed to prevent refrigerant from flowing out of the target unit but allows refrigerant to enter the target unit; S400: Timing is started and at least one parameter of the target unit is monitored to determine whether refrigerant recovery is complete; S500: When it is determined that refrigerant recovery is complete, the shut-off valve on the low-pressure gas pipe corresponding to the target unit is closed. By employing the above technical solution, this invention can solve the problems of incomplete refrigerant recovery and low efficiency in existing multi-split air conditioner refrigerant recovery systems. Specifically, by precisely controlling the shut-off valves on each pipeline, rationally guiding the refrigerant towards the target unit, and monitoring the recovery status in real time, refrigerant residue in the system pipelines can be effectively avoided, ensuring that as much refrigerant as possible is recovered, thereby solving the problem of incomplete refrigerant recovery in existing multi-split air conditioner systems.

[0018] Furthermore, in step S400 of the present invention, at least one parameter includes the pressure value on the low-pressure side of the target machine. This setting avoids problems such as incomplete or excessive refrigerant recovery due to inaccurate judgment.

[0019] Furthermore, step S400 of the present invention specifically includes: obtaining the duration of refrigerant recovery; monitoring the pressure value on the low-pressure side; and determining whether the refrigerant recovery is complete based on the duration of recovery and the pressure value on the low-pressure side. By comprehensively considering the duration of refrigerant recovery and the pressure value on the low-pressure side to determine whether the refrigerant recovery is complete, the timing of recovery can be more accurately grasped, thereby improving recovery efficiency.

[0020] Furthermore, the multi-split air conditioner also includes an external receiving device, which is connected to the target unit via piping. A valve is installed on this piping, and the control mechanism includes: S600: opening the valve to transfer refrigerant from the target unit to the external receiving device; S700: detecting the refrigerant level in the target unit; S800: closing the valve when the refrigerant level in the target unit is lower than the preset refrigerant level. This design facilitates system operation by maintenance personnel, eliminating concerns about refrigerant leakage and waste. Attached Figure Description

[0021] The preferred embodiments of the present invention are described below with reference to the accompanying drawings, in which: Figure 1 This is a flowchart of the refrigerant recovery control method for multi-split air conditioning systems of the present invention; Figure 2 This is a flowchart of an embodiment of the refrigerant recovery control method for multi-split air conditioning systems of the present invention. Detailed Implementation

[0022] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of the present invention and are not intended to limit the scope of protection of the present invention. For example, although the following embodiments are described in conjunction with multi-split air conditioners, the refrigerant recovery control method for multi-split air conditioners provided by the present invention is also applicable to other products that require refrigerant recovery but suffer from incomplete recovery or low efficiency.

[0023] It should be noted that, in the description of this invention, unless otherwise explicitly specified and limited, the terms "set" and "connection" should be interpreted broadly, for example, they can refer to a fixed connection, a detachable connection, or an integral connection. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0024] As pointed out in the background art, existing multi-split air conditioner refrigerant recovery methods suffer from incomplete recovery and low efficiency. This invention provides a refrigerant recovery control method for multi-split air conditioners, aiming to effectively solve the problems of incomplete recovery and low efficiency in refrigerant recovery by controlling the operating status of the multi-split air conditioner and the opening and closing of valves.

[0025] The present invention provides a multi-split air conditioner, which includes multiple indoor units and multiple outdoor units arranged in parallel. Each indoor unit has a high-pressure gas pipe, a low-pressure gas pipe and a liquid pipe, and each outdoor unit has a high-pressure gas pipe, a low-pressure gas pipe and a liquid pipe, which are equipped with a shut-off valve that can be independently shut off.

[0026] For example, the multi-split air conditioner of the present invention has a full cooling mode, a full heating mode, and a simultaneous cooling and heating mode.

[0027] When operating in full cooling mode, the high-pressure gas valve, low-pressure gas valve, and liquid valve of all outdoor units are open. All outdoor units are connected in parallel and work together as the system's "condenser." The high-pressure gas valve of all indoor units is closed, while the low-pressure gas valve and liquid valve are open. The electronic expansion valve of each indoor unit adjusts its opening according to its individual temperature requirements. Low-temperature, low-pressure refrigerant vapor is drawn into and compressed by the compressors of all outdoor units through the low-pressure gas pipe, becoming high-temperature, high-pressure refrigerant vapor. This vapor then enters the condenser (outdoor heat exchanger) of all outdoor units through the high-pressure gas pipe, dissipating heat to the outside air and condensing into a high-pressure, room-temperature liquid. This high-pressure liquid is then transported to each indoor unit through the liquid pipe. In each indoor unit, the refrigerant is throttled by the electronic expansion valve, becoming a low-temperature, low-pressure vapor-liquid mixture. This mixture absorbs heat and evaporates in the evaporator (indoor heat exchanger), achieving cooling. The evaporated low-temperature, low-pressure vapor returns to the outdoor unit through the low-pressure gas pipe, completing the cycle.

[0028] When operating in full heating mode, the high-pressure gas valve, low-pressure gas valve, and liquid valve of all outdoor units are open. All outdoor units are connected in parallel and work together as the system's "evaporator." The high-pressure gas valve, low-pressure gas valve, and liquid valve of all indoor units are also open. Low-temperature, low-pressure refrigerant vapor is drawn into and compressed by the compressors of all outdoor units through the low-pressure gas pipe. After becoming high-temperature, high-pressure refrigerant vapor, it is transported to each indoor unit through the high-pressure gas pipe. In the condenser of the indoor unit (which functions as a condenser at this time), the high-temperature vapor releases heat to the indoor air and condenses into a high-pressure, room-temperature liquid, achieving heating. The high-pressure liquid is collected through the liquid pipe and returned to all outdoor units. Inside the outdoor unit, the refrigerant, after being throttled by the electronic expansion valve, absorbs heat from the outside air and evaporates in the evaporator (which also functions as an evaporator at this time). The evaporated low-temperature, low-pressure vapor returns to the compressor through the low-pressure gas pipe, completing the cycle.

[0029] When operating in simultaneous cooling and heating mode, for indoor units requiring cooling, the high-pressure gas pipe valve is closed, while the low-pressure gas pipe valve and liquid pipe valve are open; for indoor units requiring heating, the high-pressure gas pipe valve is open, while the low-pressure gas pipe valve and liquid pipe valve are open. All valves on the high-pressure gas pipe, low-pressure gas pipe, and liquid pipe of the outdoor unit are open. The high-temperature, high-pressure steam discharged from the compressor first flows through the high-pressure gas pipe to the heating indoor unit, where it condenses and releases heat, achieving heating. The refrigerant flowing from the heating unit, having released some heat but still in liquid form, flows through the liquid pipe to the cooling indoor unit. In the cooling indoor unit, the refrigerant evaporates and absorbs heat after being throttled by the electronic expansion valve, achieving cooling. The low-temperature, low-pressure steam evaporated from the cooling unit returns to the compressor through the low-pressure gas pipe.

[0030] In addition, such as Figure 1 As shown, the present invention also provides a refrigerant recovery control method for multi-split air conditioners, the control method comprising: S100: When a refrigerant recovery command is received, at least one outdoor unit that receives refrigerant will be identified as the target unit; S200: Controls the operation of the multi-split air conditioner in the cooling mode and operates according to the preset operating status to stabilize the operating status of the indoor and outdoor units; S300: Close the shut-off valve on the liquid line corresponding to the target unit to block the refrigerant from flowing out of the target unit but allow the refrigerant to enter the target unit; S400: Start timing and monitor at least one parameter of the target unit to determine whether refrigerant recovery is complete; S500: When the refrigerant recovery is completed, close the shut-off valve on the low-pressure gas line corresponding to the target unit.

[0031] When a refrigerant recovery command is received, at least one outdoor unit receiving the refrigerant is identified as the target unit. This step clarifies the target location for refrigerant recovery, guiding subsequent operations. For example, engineers can operate a multi-split air conditioning system to select one or more outdoor units as the target units.

[0032] Control the multi-split air conditioner to operate in cooling mode and according to preset operating conditions to stabilize the operating status of the indoor and outdoor units. In cooling mode, the flow characteristics of the refrigerant in the system will change. Operating according to the preset operating conditions can keep the multi-split air conditioner in a stable state, which is conducive to better guiding the refrigerant to flow towards the target unit and achieving initial refrigerant collection.

[0033] Close the shut-off valve on the liquid line corresponding to the target unit to prevent refrigerant from flowing out of the target unit while allowing refrigerant to enter. This operation is to prevent the refrigerant that has already accumulated in the target unit from flowing out again in subsequent processes, ensuring that the refrigerant can be effectively retained inside the target unit.

[0034] Start timing and monitor at least one parameter of the target unit to determine whether refrigerant recovery is complete. By timing and monitoring parameters, the progress and status of refrigerant recovery can be accurately grasped, and the completion criteria can be determined based on the actual situation.

[0035] When refrigerant recovery is complete, close the shut-off valve on the low-pressure gas line corresponding to the target unit. After recovery is complete, close this shut-off valve to further ensure the stable state of the refrigerant within the system and prevent accidental refrigerant leaks.

[0036] Therefore, by precisely controlling the shut-off valves on each pipeline, rationally guiding the refrigerant to migrate to the target unit, and monitoring the recovery status in real time, it is possible to effectively avoid refrigerant residue in the system pipeline and ensure that as much refrigerant as possible is recovered, thereby solving the problem of incomplete refrigerant recovery in existing multi-split air conditioning systems.

[0037] In addition, by adjusting the system's own operating mode and controlling the shut-off valve, the refrigerant can be collected to the target unit more quickly, improving the efficiency of refrigerant recovery. This advantage is even more pronounced for large multi-split systems.

[0038] Furthermore, because refrigerant recovery is more thorough, potential safety hazards caused by refrigerant residue are avoided, such as injury to maintenance personnel due to accidental refrigerant leakage during maintenance. At the same time, it provides better conditions for subsequent maintenance work, which is conducive to improving maintenance quality.

[0039] Preferably, in step S400, at least one parameter includes the pressure value on the low-pressure side of the target machine.

[0040] When a multi-split air conditioner is operating in cooling mode and recovering refrigerant, the amount of refrigerant inside the target unit gradually increases as it migrates towards the target unit, causing changes in the pressure on its low-pressure side. When refrigerant recovery is nearing completion, the pressure on the low-pressure side of the target unit will tend towards a relatively stable specific value or reach a preset threshold range. By monitoring this pressure value and comparing it with preset judgment criteria, it is possible to accurately determine whether refrigerant recovery is complete, avoiding problems such as incomplete or excessive refrigerant recovery due to inaccurate judgment.

[0041] Preferably, such as Figure 2 As shown, step S400 specifically includes: Duration of refrigerant recovery; Monitor the pressure value on the low-pressure side; The duration of refrigerant recovery and the pressure value on the low-pressure side are used to determine whether refrigerant recovery is complete.

[0042] The time taken begins when the refrigerant recovery operation starts (i.e., step S200 controls the multi-split air conditioner to operate in cooling mode, inducing refrigerant migration). This time reflects the duration of the refrigerant recovery operation. The theoretical time required for refrigerant recovery will vary depending on the size and condition of the multi-split air conditioning system.

[0043] By using monitoring equipment such as pressure sensors installed on the low-pressure side of the target unit, the pressure value on the low-pressure side of the target unit can be obtained in real time. During the refrigerant recovery process, as refrigerant continuously accumulates in the target unit, the pressure value on the low-pressure side will change. Continuous monitoring can help to understand the dynamic changes in the pressure value.

[0044] The obtained recovery duration and monitored low-pressure side pressure values ​​are compared and analyzed with pre-set standards. For example, the pre-set standards can be a range of combinations or a specific correspondence between recovery duration and low-pressure side pressure values.

[0045] By combining the duration of refrigerant recovery with the pressure value on the low-pressure side, it is possible to determine whether refrigerant recovery is complete, thus enabling more precise timing of recovery, optimizing the entire refrigerant recovery process, improving recovery efficiency, and reducing maintenance time and costs.

[0046] Preferably, such as Figure 2 As shown, the steps for "determining whether refrigerant recovery is complete based on the duration of recovery and the pressure value on the low-pressure side" specifically include: When the refrigerant recovery lasts for a first preset duration or when the pressure value on the low-pressure side is less than or equal to the preset pressure value, the refrigerant recovery is considered complete. When the refrigerant recovery duration reaches the first preset duration and the pressure value on the low-pressure side is greater than the preset pressure value, a refrigerant recovery abnormal signal is generated.

[0047] It should be noted that the first preset duration can be determined based on factors such as the specifications of the multi-split air conditioning system, its normal operating conditions, and historical experience. This invention does not specifically limit the first preset duration. When the refrigerant recovery operation continues and reaches this time, from a time perspective, it is considered that the refrigerant has sufficient time to complete the recovery process, and the recovery can be determined to be complete.

[0048] It should be further noted that the preset pressure value can be set according to the pressure standard that the low-pressure side of the target unit should reach when the refrigerant recovery is completed normally. This invention does not impose a specific limitation on the preset pressure value. When the pressure value on the low-pressure side of the target unit is detected to drop to less than or equal to this preset pressure value, it indicates from a pressure perspective that the amount of refrigerant in the system has been reduced to a certain extent, which meets the condition of completed recovery.

[0049] When the refrigerant recovery process lasts for the first preset duration, it indicates that refrigerant recovery has been underway long enough. However, if the pressure on the low-pressure side is still higher than the preset pressure, it means that the refrigerant in the system has not decreased to the expected pressure level at the point of normal recovery completion within the specified time. This may indicate incomplete refrigerant recovery or other system anomalies, such as refrigerant leaks or malfunctioning recovery valves that could affect the normal migration of refrigerant. Therefore, the system will generate a refrigerant recovery anomaly signal to remind operators to check and address the issue promptly.

[0050] In actual refrigerant recovery processes, the recovery speed and pressure changes may vary under different operating conditions. In some cases, due to good system performance, the refrigerant recovery speed may be fast, and the low-pressure side pressure may drop below the preset value before the first preset time period is reached. In this case, recovery can be determined to be complete in advance, improving efficiency. In other cases, minor system issues may cause a slower recovery speed, but the pressure value may eventually drop below the preset value after the first preset time period, which can also be considered as indicating completion of recovery. This judgment method can better adapt to various actual situations and improve the accuracy of judgment.

[0051] Preferably, the multi-split air conditioner also includes an external receiving device, which is connected to the target unit via a pipeline, and the pipeline is equipped with a valve, such as... Figure 2 As shown, the control method also includes: S600: Open the valve to transfer the refrigerant in the target unit to the external receiving device; S700: Detects the amount of refrigerant in the target unit; S800: When the refrigerant level in the target unit is lower than the preset refrigerant level, close the valve.

[0052] After completing the aforementioned refrigerant recovery operation to the target unit and confirming successful recovery, the valve on the control pipeline is opened to connect the pipeline between the target unit and the external receiving device. Due to the pressure inside the target unit, the refrigerant will flow from the target unit to the external receiving device under the influence of the pressure difference, thus transferring the refrigerant. For example, the valve can be a solenoid valve, controlled by an electrical signal sent by the control system to open and close, offering convenient operation and rapid response.

[0053] During refrigerant transfer, it is necessary to monitor the remaining refrigerant level in the target unit in real time or periodically. There are several detection methods. For example, a refrigerant level sensor can be installed on the target unit, which can indirectly or directly measure the amount of refrigerant based on its physical properties (such as pressure, temperature, and density). Alternatively, the refrigerant level can be estimated by monitoring relevant parameters of the target unit (such as pressure and temperature) and combining them with a pre-established mathematical model. Accurate refrigerant level detection provides a basis for subsequent decisions on whether to stop the transfer.

[0054] When the refrigerant level in the target unit is detected to have dropped below the preset refrigerant level, it indicates that most of the refrigerant has been successfully transferred to the external receiving device. At this time, closing the valve in time can prevent the refrigerant level in the target unit from being too low and affecting the normal operation of the system. It can also prevent impurities such as external air from entering the target unit or the external receiving device, thus ensuring the system's airtightness and the purity of the refrigerant.

[0055] It should be noted that the preset refrigerant quantity can be set according to the design requirements, safety specifications, and subsequent maintenance or operation needs of the multi-split air conditioning system. This invention does not impose a specific limitation on the preset refrigerant quantity.

[0056] When a multi-split air conditioning system requires maintenance or repair, transferring the refrigerant to an external receiving device facilitates system operation for maintenance personnel. They no longer need to worry about refrigerant leaks or waste, allowing them to focus more on troubleshooting and component replacement, thus improving efficiency and quality of repairs. Furthermore, the recovered refrigerant can be processed and reused, reducing maintenance costs.

[0057] Preferably, the external receiving device in this invention is a pressure vessel.

[0058] For example, the pressure vessel can be flexibly selected and configured according to the size of the multi-split air conditioning system and the amount of refrigerant recovered. For large multi-split air conditioning systems, a larger capacity pressure vessel can be selected; for small systems, a smaller capacity pressure vessel can be selected. This flexibility allows the method to adapt to the refrigerant recovery needs of multi-split air conditioning systems of different sizes and types.

[0059] Preferably, when the multi-split air conditioner is currently in heating mode or simultaneously in cooling and heating mode, step S200 specifically includes: Control the multi-split air conditioner to switch from heating mode or simultaneous cooling and heating mode to cooling mode; To enable the multi-split air conditioner to operate according to the preset operating status.

[0060] In the refrigerant recovery process of multi-split air conditioners, different operating modes have a significant impact on the refrigerant flow direction and system pressure distribution. The refrigerant circulation path and pressure state differ between heating mode and simultaneous cooling and heating mode compared to cooling mode. To achieve efficient and safe refrigerant recovery, the multi-split air conditioner currently in heating mode or simultaneous cooling and heating mode needs to be switched to cooling mode. This is because in cooling mode, the refrigerant circulation direction and system pressure are more conducive to refrigerant concentration towards the target unit, facilitating subsequent recovery operations.

[0061] Preferably, such as Figure 2 As shown, "making the multi-split air conditioner operate according to the preset operating state" specifically includes: The compressors and electronic expansion valves of all outdoor units are operated at a preset frequency and a first preset opening degree, respectively. The electronic expansion valves and fans of all the indoor units are set to the second preset opening degree and preset speed, respectively.

[0062] By precisely controlling the compressor frequency and electronic expansion valve opening of the outdoor unit, as well as the electronic expansion valve opening and fan speed of the indoor unit, the operating parameters of the entire multi-split air conditioning system can be optimized, so that parameters such as pressure, temperature and flow rate within the system reach their optimal state, thereby more effectively promoting the migration of refrigerant to the target unit.

[0063] Different combinations of operating parameters will have different effects on the flow and distribution of refrigerant. By presetting these specific operating parameters, the flow direction and speed of refrigerant in the system can be precisely adjusted according to actual conditions and needs, ensuring that the refrigerant can migrate to the target unit as expected.

[0064] It should be noted that the outdoor unit's preset compressor frequency and electronic expansion valve opening (first preset opening) and the indoor unit's preset electronic expansion valve opening (second preset opening) and fan speed can be set according to the actual refrigerant recovery requirements. This invention does not impose specific limitations on these settings.

[0065] Preferably, "making the multi-split air conditioner operate according to the preset operating state" further includes: The multi-split air conditioner will run for a second period of time according to the preset operating status.

[0066] When performing refrigerant recovery in a multi-split air conditioner, switching the system to cooling mode and setting the preset operating state, followed by a second period of stable operation, provides a sufficient and stable environment for refrigerant migration. Refrigerant flow within the system is affected by various factors such as pressure and temperature. Once the system stabilizes, these parameters tend to remain constant, allowing the refrigerant to migrate more fully from non-target areas to the target unit according to a predetermined direction and pattern.

[0067] It should be noted that the second preset time can be comprehensively determined based on the size of the online air conditioning system, system pressure, temperature changes, etc. The present invention does not limit the specific value of the second preset time.

[0068] In addition, the multi-split air conditioner of the present invention also includes a controller configured to perform the above-described control method.

[0069] The technical solution of the present invention has been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after such changes or substitutions will all fall within the scope of protection of the present invention.

Claims

1. A refrigerant recovery control method for multi-split air conditioning systems, characterized in that, The multi-split air conditioner includes multiple indoor units and multiple outdoor units connected in parallel. Each indoor unit has a high-pressure gas pipe, a low-pressure gas pipe, and a liquid pipe, and each outdoor unit has a high-pressure gas pipe, a low-pressure gas pipe, and a liquid pipe, all equipped with independently shut-off valves. The control method includes: S100: When a refrigerant recovery command is received, at least one of the outdoor units that receive the refrigerant is identified as the target unit; S200: Control the multi-split air conditioner to operate in cooling mode and according to preset operating status, so as to stabilize the operating status of the indoor unit and the outdoor unit; S300: Close the shut-off valve on the liquid line corresponding to the target unit to block the refrigerant from flowing out of the target unit but allow the refrigerant to enter the target unit; S400: Start timing and monitor at least one parameter of the target unit to determine whether the refrigerant recovery is complete; S500: When it is determined that the refrigerant recovery is complete, close the shut-off valve on the low-pressure gas pipe corresponding to the target unit.

2. The refrigerant recovery control method for multi-split air conditioning systems according to claim 1, characterized in that, In step S400, the at least one parameter includes the pressure value on the low-pressure side of the target machine.

3. The refrigerant recovery control method for multi-split air conditioning systems according to claim 2, characterized in that, Step S400 specifically includes: Obtain the duration of refrigerant recovery; Monitor the pressure value on the low-pressure side; The recovery duration and the pressure value on the low-pressure side are used to determine whether the refrigerant recovery is complete.

4. The refrigerant recovery control method for multi-split air conditioning systems according to claim 3, characterized in that, The step of "determining whether the refrigerant recovery is complete based on the recovery duration and the pressure value on the low-pressure side" specifically includes: When the recovery duration reaches the first preset duration or when the pressure value on the low-pressure side is less than or equal to the preset pressure value, the refrigerant recovery is determined to be complete. When the refrigerant recovery duration reaches a first preset duration and the pressure value on the low-pressure side is greater than the preset pressure value, a refrigerant recovery abnormal signal is generated.

5. The refrigerant recovery control method for multi-split air conditioning systems according to claim 1, characterized in that, The multi-split air conditioner also includes an external receiving device, which is connected to the target unit via a pipeline, and a valve is installed on the pipeline. The control method further includes: S600: Open the valve to transfer the refrigerant in the target unit to the external receiving device; S700: Detects the amount of refrigerant in the target unit; S800: When the amount of refrigerant in the target unit is lower than the preset amount of refrigerant, close the valve.

6. The refrigerant recovery control method for multi-split air conditioning systems according to claim 5, characterized in that, The external receiving device is a pressure vessel.

7. The refrigerant recovery control method for multi-split air conditioning systems according to any one of claims 1 to 6, characterized in that, When the multi-split air conditioner is currently in heating mode or in both cooling and heating mode, step S200 specifically includes: Control the multi-split air conditioner to switch the heating mode or the simultaneous cooling and heating mode to the cooling mode; The multi-split air conditioner is made to operate according to the preset operating state.

8. The refrigerant recovery control method for multi-split air conditioning systems according to claim 7, characterized in that, "To make the multi-split air conditioner operate according to the preset operating state" specifically includes: The compressors and electronic expansion valves of all outdoor units are operated at a preset frequency and a first preset opening degree, respectively. The electronic expansion valves and fans of all the indoor units are set to the second preset opening degree and preset speed, respectively.

9. The refrigerant recovery control method for multi-split air conditioning systems according to claim 7, characterized in that, "Making the multi-split air conditioner operate according to the preset operating state" further includes: The multi-split air conditioner is then operated for a second period of time according to a preset operating state.

10. A multi-split air conditioner, characterized in that, Includes a controller configured to perform the control method according to any one of claims 1 to 9.

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