Oil return control method of multi-split air conditioning system

Abstract

The invention relates to the technical field of multi-split air conditioners, particularly provides an oil return control method of a multi-split air conditioner system, and aims to solve the technical problem that when the multi-split air conditioner system performs oil return, oil return is performed on all indoor units at the same time. In order to achieve the purpose, the control method comprises the following steps that the total number and the operation number of indoor units of the multi-split system are obtained; judging whether the proportion of the running number of the indoor units in the total number of the indoor units exceeds a first set proportion; if the proportion of the running number of the indoor units to the total number of the indoor units does not exceed the first set proportion, oil return time accumulation of the multi-split system is started; when the oil return time for starting the multi-split system is accumulated, whether the accumulated oil return time reaches the oil return set duration or not is judged; determining an indoor unit needing oil return according to a judgment result; and according to the determined indoor unit needing oil return, the indoor unit needing oil return is controlled to return oil regionally.

Description

Technical Field

[0001] The invention relates to the technical field of multi-split air conditioners, and specifically provides an oil return control method for a multi-split system. Background Art

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

[0003] When the multi-split system is running at partial load, the lubricating oil of the compressor of the multi-split system is easy to accumulate in the indoor units that are not running. As time goes by, the accumulated lubricating oil of the compressor in the multi-split system gradually increases, and the lubricating oil in the compressor gradually decreases. The unit of the multi-split system needs to recover the lubricating oil from the pipelines of the multi-split system and each indoor unit to reduce the risk of damage to the compressor due to lack of oil and wear.

[0004] However, when the multi-split system returns oil, it returns oil to all indoor units at the same time, which requires a large output capacity of the compressor, which is not conducive to the long-term stable operation of the multi-split system.

[0005] Accordingly, the art needs a new oil return control method for a multi-connected system to solve the above problems. Summary of the invention

[0006] The present invention aims to solve the above technical problem, that is, to solve the technical problem that when a multi-split system returns oil, all indoor units will return oil at the same time. To this end, the present invention provides an oil return control method for a multi-split system. The oil return control method comprises the following steps:

[0007] Obtain the total number and running number of indoor units of the multi-split system;

[0008] Determining whether the ratio of the number of operating indoor units to the total number of indoor units exceeds a first set ratio;

[0009] If the ratio of the number of operating indoor units to the total number of indoor units does not exceed a first set ratio, the oil return time accumulation of the multi-split system is started;

[0010] When the oil return time accumulation of the multi-connection system is started, it is determined whether the accumulated oil return time reaches the set oil return time;

[0011] According to the judgment result, determine the indoor unit that needs oil return;

[0012] According to the determined indoor units requiring oil return, the oil return of the indoor units requiring oil return is controlled in different areas.

[0013] In the specific implementation of the oil return control method of the multi-split system, the step of "controlling the oil return of the indoor units requiring oil return in different regions according to the determined indoor units requiring oil return" specifically includes:

[0014] Obtaining the physical locations of all indoor units of the multi-split system;

[0015] According to the physical location, divide the area to which the indoor unit belongs;

[0016] According to the determined area to which the indoor unit requiring oil return belongs, the indoor unit is controlled to return oil area by area.

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

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

[0019] In a specific implementation of the oil return control method for the multi-split system, after the step of "if the ratio of the number of running indoor units to the total number of indoor units does not exceed the first set ratio, starting the oil return time accumulation of the multi-split system" further includes:

[0020] Determining whether the multi-connection system has remote settings;

[0021] According to the judgment result, the oil return time accumulation method of the multi-connected system is determined.

[0022] In the specific implementation of the oil return control method of the multi-split system, the step of "determining the oil return time accumulation method of the multi-split system according to the judgment result" specifically includes:

[0023] If the multi-connection system does not have remote settings, the oil return time is accumulated through a timer;

[0024] If the multi-split system has remote settings, the oil return time is accumulated through the remotely set startup time and shutdown time recorded by the multi-split system.

[0025] In the specific implementation of the oil return control method of the multi-split system, the step of "determining the indoor unit that needs oil return according to the judgment result" specifically includes:

[0026] If the accumulated oil return time does not reach the set oil return time, the indoor unit does not need to return oil;

[0027] If the accumulated oil return time reaches the set oil return time, it is further determined whether the ratio of the number of running indoor units to the total number of indoor units exceeds a second set ratio to determine the indoor units that need oil return; wherein the second set ratio is less than the first set ratio.

[0028] In a specific implementation of the oil return control method for the multi-split system, the step of "if the accumulated oil return time reaches the oil return setting time, then continuing to determine whether the ratio of the number of running indoor units to the total number of indoor units exceeds a second setting ratio, so as to determine the indoor unit that needs oil return; wherein the second setting ratio is less than the first setting ratio" specifically includes:

[0029] If the ratio of the number of running indoor units to the total number of indoor units exceeds a second set ratio, all indoor units are determined to be indoor units requiring oil return;

[0030] If the ratio of the number of operating indoor units to the total number of indoor units does not exceed the second set ratio, the non-operating indoor units are determined to be indoor units requiring oil return.

[0031] In a specific implementation of the oil return control method of the multi-split system, the step of "controlling the oil return of the indoor units requiring oil return in different regions according to the determined indoor units requiring oil return" includes:

[0032] After the indoor unit requiring oil return completes the oil return, the accumulated oil return time is reset.

[0033] The present invention also provides an oil return control method for a multi-connected system. The oil return control method comprises the following steps:

[0034] Obtain the total number and running number of indoor units of the multi-split system;

[0035] Determining whether the ratio of the number of operating indoor units to the total number of indoor units exceeds a first set ratio;

[0036] If the ratio of the number of operating indoor units to the total number of indoor units exceeds a first set ratio, the oil return time accumulation of the multi-split system is not started;

[0037] If the ratio of the number of operating indoor units to the total number of indoor units does not exceed a first set ratio, the oil return time accumulation of the multi-split system is started;

[0038] Determining whether the multi-connection system has remote settings;

[0039] If the multi-connection system does not have remote settings, the oil return time is accumulated through a timer;

[0040] If the multi-split system has remote settings, the oil return time is accumulated through the remotely set startup time and shutdown time recorded by the multi-split system;

[0041] If the accumulated oil return time does not reach the set oil return time, the indoor unit does not need to return oil;

[0042] If the accumulated oil return time reaches the set oil return time, continue to determine whether the ratio of the number of running indoor units to the total number of indoor units exceeds a second set ratio to determine the indoor units that need oil return;

[0043] If the ratio of the number of running indoor units to the total number of indoor units exceeds a second set ratio, all indoor units are determined to be indoor units requiring oil return;

[0044] If the ratio of the number of running indoor units to the total number of indoor units does not exceed the second set ratio, the non-running indoor units are determined to be indoor units requiring oil return;

[0045] Obtaining the physical locations of all indoor units of the multi-split system;

[0046] According to the physical location, divide the area to which the indoor unit belongs;

[0047] By controlling the compressor frequency of the multi-split system to increase to the frequency required for the oil return of the compressor, the oil return of the indoor unit is controlled area by area;

[0048] After the indoor unit requiring oil return completes the oil return, the accumulated oil return time is reset.

[0049] When the above-mentioned technical scheme is adopted, the oil return control method of the multi-split system provided by the present invention analyzes the operating proportion and operating time of each indoor unit of the multi-split 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 system returns oil, which is beneficial to the long-term stable operation of the multi-split system.

[0050] When the multi-split system needs to return oil, it returns oil to the indoor units that meet the oil return conditions. When returning oil to the indoor units that are determined to return oil, the oil return of the indoor units that need to return oil is controlled in different regions based on the different physical locations of the indoor units that meet the oil return conditions. This can avoid abnormal pressure fluctuations in the multi-split system and large fluctuations in the compressor operating frequency caused by a large number of indoor units returning oil at the same time, which can be beneficial to the relatively stable and reliable operation of the multi-split system. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0052] Figure 1 It is a flow chart of the main steps of the oil return control method of the multi-connected system provided by the present invention;

[0053] Figure 2 It is a detailed flow chart of the steps of controlling the oil return of indoor units requiring oil return in different regions according to the determined indoor units requiring oil return in the oil return control method of the multi-split system provided by the present invention;

[0054] Figure 3 It is a flow chart of an embodiment of the oil return control method of the multi-connected system provided by the present invention;

[0055] Figure 4 It is a detailed flow chart of the steps of determining the oil return time accumulation method of the multi-split system according to the judgment result in the oil return control method of the multi-split system provided by the present invention;

[0056] Figure 5 It is a flowchart of the detailed steps of determining the indoor unit that needs oil return according to the judgment result in the oil return control method of the multi-split system provided by the present invention;

[0057] Figure 6 It is a detailed step flow chart of the oil return control method of the multi-connected system provided by the present invention. DETAILED DESCRIPTION

[0058] It should be noted that in the description of the present invention, the terms "upper", "lower", "left", "right", "inner", "outer", etc. indicating directions or positional relationships are based on the directions or positional relationships shown in the drawings, which are only for the convenience of description, and do not indicate or imply that the relevant devices or elements must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, ordinal numbers such as "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0059] In addition, it should be noted that in the description of the present invention, unless otherwise clearly specified and limited, the terms "installation" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0060] like Figure 1 As shown, the present invention proposes an oil return control method for a multi-split system. The control method may include the following steps:

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

[0062] Step S110: determining whether the ratio of the number of operating indoor units to the total number of indoor units exceeds a first set ratio;

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

[0064] Step S140: when the oil return time of the multi-split system is accumulated, it is determined whether the accumulated oil return time reaches the set oil return time;

[0065] Step S150: Determine the indoor unit that needs to return oil according to the judgment result;

[0066] Step S160: According to the determined indoor units requiring oil return, the oil return of the indoor units requiring oil return is controlled in different areas.

[0067] In this embodiment, by analyzing the operating proportion and operating time of each indoor unit in the multi-split system, 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 output capacity requirement of the compressor during the oil return of the multi-split system, which is beneficial to the long-term stable operation of the multi-split system.

[0068] When the multi-split system needs oil return, the oil is returned to the indoor units that meet the oil return conditions. When the oil is returned to the indoor units that are determined to return oil, the oil return of the indoor units that need to return oil is controlled in different regions according to the different physical locations of the indoor units that meet the oil return conditions. This can avoid abnormal pressure fluctuations in the multi-split system and large fluctuations in the operating frequency of the compressor caused by a large number of indoor units returning oil at the same time, which can be beneficial to the relatively stable and reliable operation of the multi-split system. In addition, by controlling the oil return of the indoor units that need to return oil in different regions according to the different physical locations of the indoor units that meet the oil return conditions, the frequency of the compressor for a single oil return can be reduced, as well as the noise generated during oil return.

[0069] Further, if Figure 2 As shown, step S160 of "controlling the oil return of the indoor units requiring oil return in different regions according to the determined indoor units requiring oil return" may specifically include:

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

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

[0072] Step S163: Control the indoor units to return oil area by area according to the determined areas to which the indoor units that need oil return belong.

[0073] In this embodiment, when returning oil to the indoor units that are determined to return oil, the oil return of the indoor units that need to return oil is controlled in different regions according to the different physical locations of the indoor units that meet the oil return conditions, which can avoid abnormal pressure fluctuations in the multi-split system and large fluctuations in the compressor operating frequency caused by a large number of indoor units returning oil at the same time, thereby facilitating the relatively stable and reliable operation of the multi-split system. In addition, by controlling the oil return of the indoor units that need to return oil in different regions according to the different physical locations of the indoor units that meet the oil return conditions, the compressor frequency of a single oil return can be reduced, as well as the noise generated during oil return.

[0074] In a possible implementation, all indoor units of the multi-split system are distributed in several offices, and all indoor units of the multi-split system can be divided into regions based on offices. When returning oil to the indoor units that are determined to return oil, the oil return of the indoor units that need to return oil can be controlled according to the different sub-regions of the office. This setting method can reduce the number of indoor units that return oil at the same time, thereby avoiding abnormal pressure fluctuations in the multi-split system and large fluctuations in the operating frequency of the compressor.

[0075] In some examples, all indoor units of the multi-split system are distributed in four offices, which are divided into four areas, namely, Area A, Area B, Area C, and Area D. After determining the indoor units that need oil return, the multi-split system returns oil to the indoor units that need oil return in sequence according to the areas. That is, the multi-split system first returns oil to the indoor units that need oil return in Area A; after the oil return of the indoor units that need oil return in Area A is completed, the multi-split system returns oil to the indoor units that need oil return in Area B again; after the oil return of the indoor units that need oil return in Area B is completed, the multi-split system returns oil to the indoor units that need oil return in Area C again; after the oil return of the indoor units that need oil return in Area C is completed, the multi-split system finally returns oil to the indoor units that need oil return in Area D.

[0076] Further, the step S163 of “controlling the indoor units to return oil area by area according to the determined area to which the indoor units that need oil return belong” may specifically include:

[0077] Step S1631: Control the compressor frequency of the multi-split system to increase to the frequency required for the compressor oil return, so as to control the oil return of the indoor unit in each area.

[0078] In this embodiment, by increasing the compressor frequency of the multi-split system, the lubricating oil accumulated in the indoor unit far away from the compressor can be easily returned to the compressor, which is beneficial for the multi-split system to more effectively return oil to the indoor unit far away from the compressor.

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

[0080] Step S1201: If the ratio of the number of operating indoor units to the total number of indoor units exceeds a first set ratio, the oil return time accumulation of the multi-split system is not started.

[0081] In this embodiment, when the ratio of the number of running indoor units to the total number of indoor units exceeds the first set ratio, the oil return time accumulation of the multi-split system is not started. This setting method can reduce the frequency of oil return of the multi-split system and improve the operational stability of the multi-split system. The ratio of the number of running indoor units to the total number of indoor units exceeds the first set ratio, which means that the number of running indoor units is large and the number of non-running indoor units is small. The lubricating oil of the multi-split system accumulates less in the non-running indoor units. Therefore, the multi-split system does not need to perform oil return operation, which is conducive to avoiding frequent oil return of the multi-split system, thereby improving the operational stability of the multi-split system.

[0082] In some examples, the first set ratio may be 75%.

[0083] Further, if Figure 3 As shown, after step S130 of "if the ratio of the number of running indoor units to the total number of indoor units does not exceed the first set ratio, then starting the accumulation of oil return time of the multi-split system" may also include:

[0084] Step S1310: Determine whether there is a remote setting for the multi-connection system;

[0085] Step S1320: Determine the oil return time accumulation method of the multi-connected system according to the judgment result.

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

[0087] Further, if Figure 4 As shown, step S1320 of "determining the oil return time accumulation method of the multi-split system according to the judgment result" may specifically include:

[0088] Step S1321: If there is no remote setting for the multi-link system, the oil return time is accumulated through a timer;

[0089] Step S1322: If the multi-link system has remote settings, the oil return time is accumulated through the remotely set startup time and shutdown time recorded by the multi-link system.

[0090] In this embodiment, if the multi-split system has remote settings, the oil return time can be accumulated through the remotely set startup time and shutdown time recorded by the multi-split system, thereby improving the intelligence and efficiency of the multi-split system.

[0091] Further, if Figure 5 As shown, step S150 of "determining the indoor unit that needs oil return according to the judgment result" may specifically include:

[0092] Step S1510: If the accumulated oil return time does not reach the set oil return time, the indoor unit does not need to return oil;

[0093] Step S1520: If the accumulated oil return time reaches the set oil return time, continue to determine whether the ratio of the number of running indoor units to the total number of indoor units exceeds the second set ratio to determine the indoor units that need oil return; wherein the second set ratio is less than the first set ratio.

[0094] In this embodiment, by analyzing the accumulated oil return time of the multi-split system and determining whether the indoor unit needs oil return, the frequency of the multi-split system entering the oil return operation can be reduced, thereby stabilizing the operating frequency of the compressor of the multi-split system, which is beneficial to the stable operation of the multi-split system.

[0095] In a possible implementation manner, the second set ratio may be 30%.

[0096] Further, if Figure 6 As shown, step S1520 of "if the accumulated oil return time reaches the oil return setting time, then continue to determine whether the ratio of the number of running indoor units to the total number of indoor units exceeds the second setting ratio, so as to determine the indoor units that need oil return; wherein the second setting ratio is less than the first setting ratio" may specifically include:

[0097] Step S1521: if the ratio of the number of running indoor units to the total number of indoor units exceeds the second set ratio, all indoor units are determined to be indoor units requiring oil return;

[0098] Step S1522: If the ratio of the number of operating indoor units to the total number of indoor units does not exceed the second set ratio, the non-operating indoor units are determined to be indoor units requiring oil return.

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

[0100] In a possible implementation, if the accumulated oil return time reaches the set oil return time, and the proportion of the number of running indoor units to the total number of indoor units exceeds 30% and does not exceed 75%, all indoor units are determined to be indoor units requiring oil return.

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

[0102] In a possible implementation, if the accumulated oil return time reaches the set oil return time and the proportion of the number of operating indoor units to the total number of indoor units does not exceed 30%, the non-operating indoor units are determined to be indoor units requiring oil return.

[0103] Further, if Figure 1 As shown, after step S160 of "controlling the oil return of the indoor units requiring oil return in different regions according to the determined indoor units requiring oil return" the following steps may be performed:

[0104] Step S170: After the oil return of the indoor unit requiring oil return is completed, the accumulated oil return time is reset.

[0105] In this embodiment, after the oil return of the indoor unit requiring oil return is completed, the accumulated oil return time is reset, 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 next accumulated oil return time.

[0106] like Figure 6 As shown, the present invention also proposes an oil return control method for a multi-split system. The control method may include the following steps:

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

[0108] Step S110: determining whether the ratio of the number of operating indoor units to the total number of indoor units exceeds a first set ratio;

[0109] Step S1201: If the ratio of the number of operating indoor units to the total number of indoor units exceeds a first set ratio, the oil return time accumulation of the multi-split system is not started;

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

[0111] Step S1310: Determine whether there is a remote setting for the multi-connection system;

[0112] Step S1321: If there is no remote setting for the multi-link system, the oil return time is accumulated through a timer;

[0113] Step S1322: If the multi-split system has remote settings, the oil return time is accumulated through the remotely set startup time and shutdown time recorded by the multi-split system;

[0114] Step S140: when the oil return time of the multi-split system is accumulated, it is determined whether the accumulated oil return time reaches the set oil return time;

[0115] Step S1510: If the accumulated oil return time does not reach the set oil return time, the indoor unit does not need to return oil;

[0116] Step S1520: If the accumulated oil return time reaches the oil return setting time, continue to determine whether the ratio of the number of running indoor units to the total number of indoor units exceeds a second setting ratio to determine the indoor units that need oil return; wherein the second setting ratio is less than the first setting ratio;

[0117] Step S1521: if the ratio of the number of running indoor units to the total number of indoor units exceeds the second set ratio, all indoor units are determined to be indoor units requiring oil return;

[0118] Step S1522: If the ratio of the number of operating indoor units to the total number of indoor units does not exceed the second set ratio, the non-operating indoor units are determined to be indoor units that require oil return;

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

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

[0121] Step S1631: Controlling the compressor frequency of the multi-split system to increase to the frequency required for the compressor oil return, so as to control the oil return of the indoor unit in each area;

[0122] Step S170: After the oil return of the indoor unit requiring oil return is completed, the accumulated oil return time is reset.

[0123] So far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle 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 these changes or substitutions will fall within the protection scope of the present invention.

Claims

1. A method for controlling oil return of a multi-connected system, characterized in that: The oil return control method comprises the following steps: Obtain the total number and running number of indoor units of the multi-split system; Determining whether the ratio of the number of operating indoor units to the total number of indoor units exceeds a first set ratio; If the ratio of the number of operating indoor units to the total number of indoor units does not exceed a first set ratio, the oil return time accumulation of the multi-split system is started; When the oil return time accumulation of the multi-connection system is started, it is determined whether the accumulated oil return time reaches the set oil return time; According to the judgment result, determine the indoor unit that needs oil return; According to the determined indoor units requiring oil return, the oil return of the indoor units requiring oil return is controlled in different areas.

2. The oil return control method of a multi-split system according to claim 1, characterized in that: The step of "controlling the oil return of the indoor units requiring oil return in different regions according to the determined indoor units requiring oil return" specifically includes: Obtaining the physical locations of all indoor units of the multi-split system; According to the physical location, divide the area to which the indoor unit belongs; According to the determined area to which the indoor unit requiring oil return belongs, the indoor unit is controlled to return oil area by area.

3. The oil return control method of a multi-split system according to claim 2, characterized in that: The step of "controlling the indoor units to return oil area by area according to the determined area to which the indoor units that need oil return belong" specifically includes: The compressor frequency of the multi-split system is controlled to be increased to the frequency required for the oil return of the compressor, so as to control the oil return of the indoor unit in each zone.

4. The oil return control method of a multi-split system according to claim 1, characterized in that: The oil return control method further comprises the following steps: If the ratio of the number of operating indoor units to the total number of indoor units exceeds a first set ratio, the oil return time accumulation of the multi-split system will not be started.

5. The oil return control method of a multi-split system according to claim 1, characterized in that: After the step of "if the ratio of the number of running indoor units to the total number of indoor units does not exceed the first set ratio, starting the oil return time accumulation of the multi-split system", the step further includes: Determining whether the multi-connection system has remote settings; According to the judgment result, the oil return time accumulation method of the multi-connected system is determined.

6. The oil return control method of a multi-split system according to claim 5, characterized in that: The step of "determining the oil return time accumulation method of the multi-connected system according to the judgment result" specifically includes: If the multi-connection system does not have remote settings, the oil return time is accumulated through a timer; If the multi-split system has remote settings, the oil return time is accumulated through the remotely set startup time and shutdown time recorded by the multi-split system.

7. The oil return control method of a multi-split system according to any one of claims 1 to 6, characterized in that: The steps of "determining the indoor unit that needs oil return based on the judgment result" specifically include: If the accumulated oil return time does not reach the set oil return time, the indoor unit does not need to return oil; If the accumulated oil return time reaches the set oil return time, continue to determine whether the ratio of the number of running indoor units to the total number of indoor units exceeds a second set ratio to determine the indoor units that need oil return; The second set ratio is smaller than the first set ratio.

8. The oil return control method of a multi-split system according to claim 7, characterized in that: "If the accumulated oil return time reaches the oil return setting time, continue to determine whether the ratio of the number of running indoor units to the total number of indoor units exceeds a second setting ratio to determine the indoor unit that needs oil return; wherein the second setting ratio is less than the first setting ratio" specifically includes: If the ratio of the number of running indoor units to the total number of indoor units exceeds a second set ratio, all indoor units are determined to be indoor units requiring oil return; If the ratio of the number of operating indoor units to the total number of indoor units does not exceed the second set ratio, the non-operating indoor units are determined to be indoor units requiring oil return.

9. The oil return control method of a multi-split system according to claim 1, characterized in that: The step of "controlling the oil return of the indoor units requiring oil return in different regions according to the determined indoor units requiring oil return" includes: After the indoor unit requiring oil return completes the oil return, the accumulated oil return time is reset.

10. A method for controlling oil return of a multi-connected system, characterized in that: The oil return control method comprises the following steps: Obtain the total number and running number of indoor units of the multi-split system; Determining whether the ratio of the number of operating indoor units to the total number of indoor units exceeds a first set ratio; If the ratio of the number of operating indoor units to the total number of indoor units exceeds a first set ratio, the oil return time accumulation of the multi-split system is not started; If the ratio of the number of operating indoor units to the total number of indoor units does not exceed a first set ratio, the oil return time accumulation of the multi-split system is started; Determining whether the multi-connection system has remote settings; If the multi-connection system does not have remote settings, the oil return time is accumulated through a timer; If the multi-split system has remote settings, the oil return time is accumulated through the remotely set startup time and shutdown time recorded by the multi-split system; If the accumulated oil return time does not reach the set oil return time, the indoor unit does not need to return oil; If the accumulated oil return time reaches the set oil return time, continue to determine whether the ratio of the number of running indoor units to the total number of indoor units exceeds a second set ratio to determine the indoor units that need oil return; If the ratio of the number of running indoor units to the total number of indoor units exceeds a second set ratio, all indoor units are determined to be indoor units requiring oil return; If the ratio of the number of running indoor units to the total number of indoor units does not exceed the second set ratio, the non-running indoor units are determined to be indoor units requiring oil return; Obtaining the physical locations of all indoor units of the multi-split system; According to the physical location, divide the area to which the indoor unit belongs; By controlling the compressor frequency of the multi-split system to increase to the frequency required for the oil return of the compressor, the oil return of the indoor unit is controlled area by area; After the indoor unit requiring oil return completes the oil return, the accumulated oil return time is reset.

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