Oil return control method for multi-connected system

Abstract

The present application relates to the technical field of multi-connected air conditioner, and particularly provides an oil return control method of a multi-connected system, aiming to solve the technical problem that the multi-connected system simultaneously returns oil to all indoor units at the same time. To this end, the control method provided by the present application comprises the following steps: obtaining the total number of indoor units of the multi-connected system and the number of running indoor units; judging whether the proportion of the number of running indoor units to the total number of indoor units exceeds a first set proportion; if the proportion of the number of running indoor units to the total number of indoor units does not exceed the first set proportion, starting the oil return time accumulation of the multi-connected system; when the oil return time accumulation of the multi-connected system is started, judging whether the accumulated oil return time reaches a set oil return time length; according to the judgment result, determining the indoor units that need to return oil; and according to the determined indoor units that need to return oil, controlling the indoor units that need to return oil to return oil in different areas.

Description

Technical Field

[0001] This invention relates to the field of multi-split air conditioning technology, specifically providing a method for controlling the oil return of a multi-split system. Background Technology

[0002] A multi-split air conditioning system refers to an air conditioning system in which one outdoor unit is connected to two or more indoor units through piping. Currently, multi-split air conditioning systems are being used more and more widely in small and medium-sized buildings and some public buildings.

[0003] When a multi-split air conditioning system is operating under partial load, compressor lubricating oil tends to accumulate in the indoor units that are not in operation. Over time, the accumulated compressor lubricating oil in the multi-split system gradually increases, while the amount of lubricating oil in the compressor gradually decreases. Therefore, the multi-split system needs to recover lubricating oil from the system's piping and each indoor unit to reduce the risk of compressor damage due to insufficient oil.

[0004] However, when a multi-split air conditioning system performs oil return, it returns oil to all indoor units simultaneously, which requires a large output capacity from the compressor and is not conducive to the long-term stable operation of the multi-split air conditioning system.

[0005] Accordingly, there is a need in the field for a new oil return control method for multi-split air conditioning systems to solve the above problems. Summary of the Invention

[0006] This invention aims to solve the aforementioned technical problem, namely, the problem that multi-split air conditioning systems simultaneously return oil to all indoor units at the same time during oil return. To this end, this invention provides an oil return control method for multi-split air conditioning systems. This oil return control method includes the following steps:

[0007] Obtain the total number of indoor units and the number in operation of the multi-split air conditioning system;

[0008] Determine whether the proportion of the number of operating indoor units to the total number of indoor units exceeds a first preset proportion;

[0009] If the proportion of the number of indoor units in operation to the total number of indoor units does not exceed the first set proportion, then the oil return time of the multi-split system is started.

[0010] When the oil return time accumulation of the multi-unit system is started, it is determined whether the accumulated oil return time has reached the set oil return time.

[0011] Based on the assessment results, it was determined that the indoor unit requires oil return.

[0012] Based on the identified indoor units requiring oil return, the oil return of the indoor units requiring oil return is controlled in separate zones.

[0013] In the specific implementation of the oil return control method for the above-mentioned multi-split air conditioning system, the step of "controlling the oil return of the indoor units that need oil return by region according to the determined indoor units that need oil return" specifically includes:

[0014] Obtain the physical locations of all indoor units in the multi-split air conditioning system;

[0015] The area to which the indoor unit belongs is determined based on its physical location;

[0016] Based on the determined area to which the indoor unit requires oil return, the indoor unit is controlled to return oil to each area sequentially.

[0017] In a specific implementation of the oil return control method for the above-mentioned multi-split air conditioning system, the step of "controlling the indoor unit to return oil region by region according to the determined area to which the indoor unit to return oil" specifically includes: controlling the compressor frequency of the multi-split air conditioning system to increase to the frequency required for the compressor to return oil, so as to control the indoor unit to return oil region by region.

[0018] In a specific implementation of the oil return control method for the above-mentioned multi-split air conditioning system, the oil return control method further includes the following steps: if the proportion of the number of indoor units in operation to the total number of indoor units exceeds a first set proportion, then the oil return time accumulation of the multi-split air conditioning system is not started.

[0019] In the specific implementation of the above-mentioned oil return control method for multi-split air conditioning systems, the step of "if the proportion of the number of indoor units in operation to the total number of indoor units does not exceed a first preset proportion, then the oil return time accumulation of the multi-split air conditioning system is started" further includes:

[0020] Determine whether the multi-unit system has remote settings;

[0021] Based on the judgment result, the method for accumulating the oil return time of the multi-split system is determined.

[0022] In the specific implementation of the oil return control method for the above-mentioned multi-split air conditioning system, the step of "determining the oil return time accumulation method of the multi-split air conditioning system based on the judgment result" specifically includes:

[0023] If the multi-split air conditioning system does not have remote settings, the oil return time is accumulated using a timer;

[0024] If the multi-split air conditioning system has remote settings, the oil return time is accumulated by using the start-up and shutdown times of the remote settings recorded by the multi-split air conditioning system.

[0025] In the specific implementation of the oil return control method for the above-mentioned multi-split air conditioning system, the step of "determining the indoor unit that needs oil return based on the judgment result" specifically includes:

[0026] If the cumulative oil return time does not reach the set oil return duration, the indoor unit does not need to return oil.

[0027] If the cumulative oil return time reaches the oil return set duration, then it is further determined whether the proportion of the number of indoor units in operation to the total number of indoor units exceeds the second set proportion, so as to determine the indoor units that need oil return; wherein, the second set proportion is less than the first set proportion.

[0028] In a specific implementation of the oil return control method for the aforementioned multi-split air conditioning system, the step of "if the cumulative oil return time reaches the oil return set duration, then continue to determine whether the proportion of the number of indoor units in operation to the total number of indoor units exceeds a second set proportion, so as to determine the indoor units that need oil return; wherein, the second set proportion is less than the first set proportion" specifically includes:

[0029] If the proportion of the number of indoor units in operation to the total number of indoor units exceeds the second preset proportion, then all indoor units are determined to be indoor units that require oil return.

[0030] If the proportion of the number of operating indoor units to the total number of indoor units does not exceed the second set proportion, then the indoor units that are not operating are determined to be indoor units that require oil return.

[0031] In the specific implementation of the oil return control method for the above-mentioned multi-split air conditioning system, the step of "controlling the oil return of the indoor unit requiring oil return by region according to the determined indoor unit requiring oil return" includes:

[0032] After the indoor unit requiring oil return has completed its oil return process, the cumulative oil return time is reset to zero.

[0033] This invention also provides a method for controlling the return oil flow in a multi-split air conditioning system. The method includes the following steps:

[0034] Obtain the total number of indoor units and the number in operation of the multi-split air conditioning system;

[0035] Determine whether the proportion of the number of operating indoor units to the total number of indoor units exceeds a first preset proportion;

[0036] If the proportion of the number of indoor units in operation to the total number of indoor units exceeds a first set proportion, the oil return time accumulation of the multi-split system will not be started.

[0037] If the proportion of the number of indoor units in operation to the total number of indoor units does not exceed the first set proportion, then the oil return time of the multi-split system is started.

[0038] Determine whether the multi-unit system has remote settings;

[0039] If the multi-split air conditioning system does not have remote settings, the oil return time is accumulated using a timer;

[0040] If the multi-split air conditioning system has remote settings, the oil return time is accumulated by using the start-up and shutdown times of the remote settings recorded by the multi-split air conditioning system.

[0041] If the cumulative oil return time does not reach the set oil return duration, the indoor unit does not need to return oil.

[0042] If the cumulative oil return time reaches the oil return set duration, then it is further determined whether the proportion of the number of indoor units in operation to the total number of indoor units exceeds the second set proportion, so as to determine the indoor units that need oil return;

[0043] If the proportion of the number of indoor units in operation to the total number of indoor units exceeds the second preset proportion, then all indoor units are determined to be indoor units that require oil return.

[0044] If the proportion of the number of indoor units in operation to the total number of indoor units does not exceed the second preset proportion, then the indoor units that are not in operation are determined to be indoor units that require oil return.

[0045] Obtain the physical locations of all indoor units in the multi-split air conditioning system;

[0046] The area to which the indoor unit belongs is determined based on its physical location;

[0047] By controlling the compressor frequency of the multi-split system to be increased to the frequency required for the compressor to return oil, the indoor unit can be controlled to return oil in zones.

[0048] After the indoor unit requiring oil return has completed its oil return process, the cumulative oil return time is reset to zero.

[0049] When the above technical solution is adopted, the oil return control method for multi-split air conditioning systems provided by the present invention analyzes the operating ratio and operating time of each indoor unit of the multi-split air conditioning system, and performs oil return operation on the indoor unit that meets the oil return conditions. This can reduce the operating frequency of the compressor during the oil return operation, thereby reducing the output capacity requirement of the compressor when the multi-split air conditioning system returns oil, which is conducive to the long-term stable operation of the multi-split air conditioning system.

[0050] When a multi-split air conditioning system requires oil return, oil is returned to the indoor units that meet the return conditions. By controlling the oil return of the indoor units that meet the return conditions according to their physical location, the system can avoid abnormal pressure fluctuations and large fluctuations in compressor operating frequency caused by a large number of indoor units returning oil at the same time. This contributes to the relatively stable and reliable operation of the multi-split air conditioning system. Attached Figure Description

[0051] The preferred embodiments of the present invention are described below with reference to the accompanying drawings, in which:

[0052] Figure 1 This is a flowchart of the main steps of the oil return control method for the multi-unit system provided by the present invention;

[0053] Figure 2 This is a flowchart showing the detailed steps of the oil return control method for a multi-split air conditioning system provided by the present invention, which controls the oil return of indoor units that require oil return in different zones according to the determined indoor units that require oil return.

[0054] Figure 3 This is a flowchart of an embodiment of the oil return control method for a multi-unit air conditioning system provided by the present invention;

[0055] Figure 4 This is a detailed flowchart of the steps in the oil return control method for a multi-split air conditioning system provided by the present invention, which determines the cumulative method of oil return time for the multi-split air conditioning system based on the judgment result.

[0056] Figure 5 This is a flowchart showing the detailed steps of determining the indoor unit requiring oil return based on the judgment result in the oil return control method for a multi-split air conditioning system provided by the present invention.

[0057] Figure 6 This is a detailed flowchart of the oil return control method for the multi-unit system provided by the present invention. Detailed Implementation

[0058] It should be noted that in the description of this invention, terms such as "upper," "lower," "left," "right," "inner," and "outer," which indicate direction or positional relationships, are based on the direction or positional relationships shown in the accompanying drawings. These are used merely for ease of description and do not indicate or imply that the relevant devices or elements must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention. Furthermore, ordinal numbers such as "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0059] Furthermore, it should be noted that, in the description of this invention, unless otherwise explicitly specified and limited, the terms "installation" and "connection" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0060] like Figure 1 As shown, this invention proposes a method for controlling the return oil flow in a multi-split air conditioning system. This control method may include the following steps:

[0061] Step S100: Obtain the total number of indoor units and the number in operation of the multi-split system;

[0062] Step S110: Determine whether the proportion of the number of indoor units in operation to the total number of indoor units exceeds the first preset proportion;

[0063] Step S130: If the proportion of the number of indoor units in operation to the total number of indoor units does not exceed the first set proportion, then start the oil return time accumulation of the multi-split system;

[0064] Step S140: When the oil return time of the multi-split system is started to accumulate, determine whether the accumulated oil return time has reached the set oil return time.

[0065] Step S150: Based on the judgment result, determine the indoor unit that needs oil return;

[0066] Step S160: Based on the determined indoor units that require oil return, control the oil return of the indoor units that require oil return in different areas.

[0067] In this embodiment, by analyzing the operating ratio and operating time of each indoor unit in the multi-split air conditioning system, the oil return operation is performed on the indoor units that meet the oil return conditions. This can reduce the operating frequency of the compressor during the oil return operation, thereby reducing the compressor's output capacity requirement during the oil return operation of the multi-split air conditioning system, which is conducive to the long-term stable operation of the multi-split air conditioning system.

[0068] When a multi-split air conditioning system requires oil return, oil is returned only to the indoor units that meet the return conditions. By controlling the oil return of these units in different zones based on their physical location, the system avoids abnormal pressure fluctuations and large fluctuations in compressor operating frequency caused by a large number of indoor units returning oil simultaneously. This contributes to the relatively stable and reliable operation of the multi-split system. Furthermore, controlling the oil return of these units in different zones by different physical locations reduces the compressor frequency during a single oil return cycle and lowers the noise generated during the return process.

[0069] Furthermore, such as Figure 2 As shown, step S160, "controlling the oil return of indoor units requiring oil return according to the determined number of indoor units requiring oil return, by region," may specifically include:

[0070] Step S161: Obtain the physical locations of all indoor units in the multi-split system;

[0071] Step S162: Divide the area to which the indoor unit belongs based on its physical location;

[0072] Step S163: Based on the determined area of ​​the indoor unit that needs oil return, control the indoor unit to return oil to each area one by one.

[0073] In this embodiment, when returning oil to the indoor units that have been determined to return oil, the oil return to the indoor units requiring oil return is controlled in different zones based on the different physical locations of the indoor units that have reached the oil return conditions. This avoids abnormal pressure fluctuations and large fluctuations in compressor operating frequency in the multi-split system caused by a large number of indoor units returning oil at the same time, thus promoting the relatively stable and reliable operation of the multi-split system. Furthermore, by controlling the oil return to the indoor units requiring oil return in different zones based on the different physical locations of the indoor units that have reached the oil return conditions, the compressor frequency of a single oil return and the noise generated during oil return can be reduced.

[0074] In one possible implementation, all indoor units of the multi-split air conditioning system are distributed across several offices, dividing the system into zones based on these offices. When oil return is required for an indoor unit in a specific zone, oil return can be initiated according to the designated zone within the office. This configuration reduces the number of indoor units undergoing oil return simultaneously, thereby preventing abnormal pressure fluctuations and large fluctuations in compressor operating frequency within the multi-split system.

[0075] In some examples, all indoor units of the multi-split air conditioning system are distributed across four offices, divided into four zones: Zone A, Zone B, Zone C, and Zone D. After identifying the indoor units requiring lubrication, the multi-split system performs lubrication on these units sequentially according to their zone. Specifically, the system first performs lubrication on the units in Zone A; after completing lubrication on the units in Zone A, it then performs lubrication on the units in Zone B; after completing lubrication on the units in Zone B, it performs lubrication on the units in Zone C; and finally, it performs lubrication on the units in Zone D.

[0076] Furthermore, step S163, "controlling the indoor unit to return oil zone by zone according to the determined area where the indoor unit to return oil needs to be located," may specifically include:

[0077] Step S1631: By controlling the compressor frequency of the multi-split system to increase to the frequency required for compressor oil return, the indoor units are controlled to return oil in zones.

[0078] In this embodiment, by increasing the compressor frequency of the multi-split system, the lubricating oil accumulated in the indoor units that are far from the compressor can easily flow back towards the compressor, which is beneficial for the multi-split system to return oil to the indoor units that are far from the compressor more effectively.

[0079] Furthermore, the oil return control method may also include the following steps:

[0080] Step S1201: If the proportion of the number of indoor units in operation to the total number of indoor units exceeds the first set proportion, the oil return time accumulation of the multi-split system will not be started.

[0081] In this embodiment, when the proportion of operating indoor units to the total number of indoor units exceeds a first preset ratio, the lubrication return time of the multi-split system is not activated. This setting reduces the frequency of lubrication return in the multi-split system, improving its operational stability. A proportion exceeding the first preset ratio means a larger number of indoor units are operating and a smaller number are not. Less lubricating oil accumulates in the non-operating indoor units, thus eliminating the need for lubrication return operations and improving overall system stability.

[0082] In some examples, the initial set ratio can be 75%.

[0083] Furthermore, such as Figure 3 As shown, step S130, "if the proportion of the number of operating indoor units to the total number of indoor units does not exceed the first set proportion, then start the oil return time accumulation of the multi-split system," may further include:

[0084] Step S1310: Determine whether remote settings exist in the multi-split system;

[0085] Step S1320: Based on the judgment result, determine the method for accumulating the oil return time of the multi-split system.

[0086] In this embodiment, if the proportion of the number of operating indoor units to the total number of indoor units does not exceed the first set proportion, it means that the number of operating indoor units is small and the number of non-operating indoor units is large. As a result, a large amount of lubricating oil in the multi-split system accumulates in the non-operating indoor units. Therefore, it is necessary for the multi-split system to perform an oil return operation.

[0087] Furthermore, such as Figure 4 As shown, step S1320, "determining the oil return time accumulation method of the multi-split system based on the judgment result," may specifically include:

[0088] Step S1321: If the multi-split system does not have remote settings, then the oil return time is accumulated by a timer;

[0089] Step S1322: If the multi-split system has remote settings, the oil return time is accumulated by using the start-up and shutdown times of the remote settings recorded by the multi-split system.

[0090] In this embodiment, if the multi-split air conditioning system has remote settings, the oil return time can be accumulated by using the remote settings start-up and shutdown times recorded by the multi-split air conditioning system, thereby improving the intelligence and efficiency of the multi-split air conditioning system.

[0091] Furthermore, such as Figure 5 As shown, step S150, "determining the indoor unit requiring oil return based on the judgment result," may specifically include:

[0092] Step S1510: If the cumulative oil return time has not reached the set oil return duration, the indoor unit does not need to return oil;

[0093] Step S1520: If the cumulative oil return time reaches the oil return set duration, then continue to determine whether the proportion of the number of indoor units in operation to the total number of indoor units exceeds the second set proportion, so as to determine the indoor units that need oil return; wherein, the second set proportion is less than the first set proportion.

[0094] In this embodiment, by analyzing the cumulative oil return time of the multi-split air conditioning system, it is determined whether the indoor unit needs to return oil. This can reduce the frequency of the multi-split air conditioning system entering the oil return operation, thereby stabilizing the operating frequency of the compressor in the multi-split air conditioning system and promoting stable operation of the multi-split air conditioning system.

[0095] In one possible implementation, the second set ratio can be 30%.

[0096] Furthermore, such as Figure 6 As shown, step S1520, "if the cumulative oil return time reaches the oil return set duration, then it is further determined whether the proportion of the number of operating indoor units to the total number of indoor units exceeds the second set proportion, so as to determine the indoor units that need oil return; wherein, the second set proportion is less than the first set proportion," may specifically include:

[0097] Step S1521: If the proportion of the number of indoor units in operation to the total number of indoor units exceeds the second set proportion, then all indoor units are determined to be indoor units that require oil return.

[0098] Step S1522: If the proportion of the number of indoor units in operation to the total number of indoor units does not exceed the second set proportion, then the indoor units that are not in operation are determined to be indoor units that need oil return.

[0099] In this embodiment, if the proportion of the number of indoor units in operation to the total number of indoor units does not exceed the second set proportion, that is, the number of indoor units in operation is small and the number of indoor units not in operation is large, oil can be returned only to the indoor units not in operation, thereby reducing the number of indoor units that return oil. This can reduce the output capacity requirement of the compressor of the multi-split system and thus maintain the long-term stable operation of the multi-split system.

[0100] In one possible implementation, if the cumulative oil return time reaches the set oil return duration, and the number of indoor units in operation accounts for more than 30% but less than 75% of the total number of indoor units, then all indoor units are determined to be indoor units requiring oil return.

[0101] In some examples, when all indoor units are being returned to oil, the electronic expansion valve of the previously operating indoor unit can be closed or adjusted to a smaller opening, and the fan speed of the previously operating indoor unit can be reduced slowly to maximize the use of refrigerant or heat in the indoor heat exchanger to maintain the indoor ambient temperature, thereby reducing energy waste.

[0102] In one possible implementation, if the cumulative oil return time reaches the set oil return duration and the proportion of the number of indoor units in operation to the total number of indoor units does not exceed 30%, then the indoor units that are not in operation are determined to be indoor units that require oil return.

[0103] Furthermore, such as Figure 1 As shown, after step S160, which involves "controlling the oil return of indoor units that require oil return according to the determined indoor units that require oil return, by region," the following may be included:

[0104] Step S170: After the indoor unit that needs to return oil has completed the oil return process, the cumulative oil return time is reset to zero.

[0105] In this embodiment, after the indoor unit that needs to return oil has completed the oil return process, the cumulative oil return time is reset to zero, and the multi-split system prepares for the next oil return. The current oil return time of the multi-split system will not affect the cumulative oil return time for the next cycle.

[0106] like Figure 6 As shown, this invention also proposes a method for controlling the return oil flow in a multi-split air conditioning system. This control method may include the following steps:

[0107] Step S100: Obtain the total number of indoor units and the number in operation of the multi-split system;

[0108] Step S110: Determine whether the proportion of the number of indoor units in operation to the total number of indoor units exceeds the first preset proportion;

[0109] Step S1201: If the proportion of the number of indoor units in operation to the total number of indoor units exceeds the first set proportion, the oil return time accumulation of the multi-split system will not be started;

[0110] Step S130: If the proportion of the number of indoor units in operation to the total number of indoor units does not exceed the first set proportion, then start the oil return time accumulation of the multi-split system;

[0111] Step S1310: Determine whether remote settings exist in the multi-split system;

[0112] Step S1321: If the multi-split system does not have remote settings, then the oil return time is accumulated by a timer;

[0113] Step S1322: If the multi-split system has remote settings, then the oil return time is accumulated by using the start-up and shutdown times of the remote settings recorded by the multi-split system.

[0114] Step S140: When the oil return time of the multi-split system is started to accumulate, determine whether the accumulated oil return time has reached the set oil return time.

[0115] Step S1510: If the cumulative oil return time has not reached the set oil return duration, the indoor unit does not need to return oil;

[0116] Step S1520: If the cumulative oil return time reaches the oil return set duration, then continue to determine whether the proportion of the number of indoor units in operation to the total number of indoor units exceeds the second set proportion, so as to determine the indoor units that need oil return; wherein, the second set proportion is less than the first set proportion;

[0117] Step S1521: If the proportion of the number of indoor units in operation to the total number of indoor units exceeds the second set proportion, then all indoor units are determined to be indoor units that require oil return.

[0118] Step S1522: If the proportion of the number of indoor units in operation to the total number of indoor units does not exceed the second set proportion, then the indoor units that are not in operation are determined to be indoor units that need oil return.

[0119] Step S161: Obtain the physical locations of all indoor units in the multi-split system;

[0120] Step S162: Divide the area to which the indoor unit belongs based on its physical location;

[0121] Step S1631: By controlling the compressor frequency of the multi-split system to increase to the frequency required for compressor oil return, the indoor units are controlled to return oil zone by zone;

[0122] Step S170: After the indoor unit that needs to return oil has completed the oil return process, the cumulative oil return time is reset to zero.

[0123] 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 method of controlling oil return in a multi-split system, characterized by, The oil return control method comprises the following steps: Obtaining the total number of indoor units of the multi-connected system and the running number of indoor units; Judging whether the proportion of the running number of indoor units to the total number of indoor units exceeds a first set proportion; If the proportion of the running number of indoor units to the total number of indoor units does not exceed the first set proportion, starting the oil return time accumulation of the multi-connected system; When the oil return time accumulation of the multi-connected system is started, judging whether the accumulated oil return time reaches an oil return set time length; According to the judgment result, determining the indoor units that need to return oil; According to the determined indoor units that need to return oil, controlling the indoor units that need to return oil in different areas; The step of "determining the indoor units that need to return oil according to the judgment result" specifically comprises: If the accumulated oil return time does not reach the oil return set time length, the indoor units do not need to return oil; If the accumulated oil return time reaches the oil return set time length, continue to judge whether the proportion of the running number of indoor units to the total number of indoor units exceeds a second set proportion to determine the indoor units that need to return oil; wherein the second set proportion is less than the first set proportion; The step of "if the accumulated oil return time reaches the oil return set time length, continue to judge whether the proportion of the running number of indoor units to the total number of indoor units exceeds a second set proportion to determine the indoor units that need to return oil; wherein the second set proportion is less than the first set proportion" specifically comprises: If the proportion of the running number of indoor units to the total number of indoor units exceeds the second set proportion, all indoor units are determined as the indoor units that need to return oil; If the proportion of the running number of indoor units to the total number of indoor units does not exceed the second set proportion, the indoor units that do not run are determined as the indoor units that need to return oil.

2. The oil return control method of a multi-split system according to claim 1, wherein The step of "controlling the indoor units that need to return oil in different areas according to the determined indoor units that need to return oil" specifically comprises: Obtaining the physical positions of all indoor units of the multi-connected system; According to the physical positions, dividing the areas to which the indoor units belong; According to the area to which the determined indoor units that need to return oil belong, controlling the indoor units to return oil in areas.

3. The oil return control method of a package system according to claim 2, wherein The step of "controlling the indoor units to return oil in areas according to the area to which the determined indoor units that need to return oil belong" specifically comprises: By controlling the compressor frequency of the multi-connected system to increase to the frequency required by the compressor to return oil, the indoor units are controlled to return oil in areas.

4. The oil return control method of a package system according to claim 1, wherein The oil return control method further comprises the following steps: If the proportion of the running number of indoor units to the total number of indoor units exceeds the first set proportion, the oil return time accumulation of the multi-connected system is not started.

5. The oil return control method of a package system according to claim 1, wherein After the step of "if the proportion of the running number of indoor units to the total number of indoor units does not exceed the first set proportion, starting the oil return time accumulation of the multi-connected system", further comprising: Judging whether there is a remote setting of the multi-connected system; According to the judgment result, determining the oil return time accumulation mode of the multi-connected system.

6. The oil return control method of a package system according to claim 5, wherein The step of "determining the oil return time accumulation mode of the multi-connected system according to the judgment result" specifically comprises: If there is no remote setting of the multi-connected system, the oil return time is accumulated by a timer; If the multi-connected system has remote setting, the start-up time and the shut-down time of the remote setting recorded by the multi-connected system are used to accumulate the oil return time.

7. The oil return control method of a package system according to claim 1, wherein The step of "controlling the oil return of the indoor unit in need of oil return according to the determined indoor unit in need of oil return" comprises the following steps: After the oil return of the indoor unit in need of oil return is completed, the accumulated oil return time is cleared.

8. A method of controlling oil return in a multi-split system, the method comprising: The oil return control method comprises the following steps: Obtain the total number of indoor units of the multi-connected system and the number of running indoor units; Determine whether the proportion of the number of running indoor units to the total number of indoor units exceeds a first set proportion; If the proportion of the number of running indoor units to the total number of indoor units exceeds the first set proportion, the oil return time accumulation of the multi-connected system is not started; If the proportion of the number of running indoor units to the total number of indoor units does not exceed the first set proportion, the oil return time accumulation of the multi-connected system is started; Determine whether the multi-connected system has remote setting; If the multi-connected system does not have remote setting, the oil return time is accumulated by a timer; If the multi-connected system has remote setting, the start-up time and the shut-down time of the remote setting recorded by the multi-connected system are used to accumulate the oil return time; If the accumulated oil return time does not reach the set oil return time length, the indoor unit does not need to return oil; If the accumulated oil return time reaches the set oil return time length, it is determined whether the proportion of the number of running indoor units to the total number of indoor units exceeds a second set proportion to determine the indoor unit in need of oil return, wherein the second set proportion is less than the first set proportion; If the proportion of the number of running indoor units to the total number of indoor units exceeds the second set proportion, all indoor units are determined to be the indoor unit in need of oil return; If the proportion of the number of running indoor units to the total number of indoor units does not exceed the second set proportion, the indoor unit that is not running is determined to be the indoor unit in need of oil return; Obtain the physical positions of all indoor units of the multi-connected system; According to the physical positions, the areas to which the indoor units belong are divided; The frequency of the compressor of the multi-connected system is controlled to increase to the frequency required for oil return of the compressor, so as to control the indoor units to return oil in areas; After the oil return of the indoor unit in need of oil return is completed, the accumulated oil return time is cleared.

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