A multi-split system oil return control method, device and multi-split system

Abstract

The present invention discloses a multi-split system oil return control method, device, and multi-split system. The method comprises: when the multi-split system is operating in heating mode and oil return is required, detecting the outdoor ambient temperature and / or the indoor unit startup load rate; and determining whether to execute the heating oil return mode or the cooling oil return mode based on the outdoor ambient temperature and / or the indoor unit startup load rate. The present invention selects different oil return control modes based on the outdoor ambient temperature and / or the indoor unit startup load rate. When the outdoor ambient temperature is low and the indoor unit startup load rate is high, oil return is selected in the heating mode without switching to the cooling mode, thereby avoiding affecting the indoor heating effect and ensuring the user experience of the multi-split system during oil return.

Description

Technical Field

[0001] The present invention relates to the technical field of multi-split units, and in particular to a multi-split unit system oil return control method and device, and a multi-split unit system. Background Art

[0002] To ensure compressor reliability, VRF systems perform oil return operations after a certain period of operation, returning refrigerant oil accumulated in the pipes and heat exchangers to the compressor. Under existing control systems, when oil return is required during heating operation, the VRF system switches to cooling mode. In this case, the indoor unit stops heating, affecting the indoor heating effect, causing the indoor temperature to drop and impacting the user experience.

[0003] Currently, no effective solution has been proposed to the problem that in the existing technology, the oil return in the heating mode of the multi-split system needs to be frequently switched to the cooling mode, which affects the indoor heating effect. Summary of the Invention

[0004] The embodiments of the present invention provide a multi-split system oil return control method, device and multi-split system to solve the problem in the prior art that the multi-split system oil return in heating mode needs to be frequently switched to cooling mode, affecting the indoor heating effect.

[0005] In order to solve the above technical problems, the present invention provides a multi-split system oil return control method, wherein the method includes: when the multi-split system needs oil return in heating mode, detecting the outdoor ambient temperature and / or the indoor unit startup load rate; according to the outdoor ambient temperature and / or the indoor unit startup load rate, determining to execute the heating oil return mode or the cooling oil return mode.

[0006] Furthermore, detecting the startup load rate of the indoor unit includes: obtaining the rated capacity of the currently powered-on indoor unit and the total rated capacity of the multi-split system; and calculating the startup load rate of the indoor unit based on the rated capacity of the powered-on indoor unit and the total rated capacity.

[0007] Furthermore, according to the outdoor ambient temperature, determining whether to execute the heating oil return mode or the cooling oil return mode includes: comparing the outdoor ambient temperature with a preset temperature threshold; if the outdoor ambient temperature is less than the preset temperature threshold, determining to execute the heating oil return mode; if the outdoor ambient temperature is greater than or equal to the preset temperature threshold, determining to execute the cooling oil return mode.

[0008] Furthermore, based on the indoor unit startup load rate, determining whether to execute the heating oil return mode or the cooling oil return mode includes: comparing the indoor unit startup load rate and a preset load rate threshold; if the indoor unit startup load rate is less than the preset load rate threshold, determining to execute the cooling oil return mode; if the indoor unit startup load rate is greater than or equal to the preset load rate threshold, determining to execute the heating oil return mode.

[0009] Furthermore, according to the outdoor ambient temperature and the indoor unit startup load rate, it is determined to execute the heating oil return mode or the cooling oil return mode, including: determining the temperature range in which the outdoor ambient temperature is located, and determining the load rate range in which the indoor unit startup load rate is located; wherein, multiple temperature ranges and multiple load rate ranges are preset, and a corresponding relationship between each temperature range, each load rate range and the oil return mode is preset; according to the corresponding relationship, the oil return mode corresponding to the temperature range and the load rate range is determined; wherein, the oil return mode includes the heating oil return mode and the cooling oil return mode.

[0010] Furthermore, determining to execute the heating oil return mode includes: controlling the multi-split system to maintain operation in the heating mode, controlling the flow control valves of all indoor units to be adjusted to a preset maximum opening, and controlling the compressor to maintain operation at a preset high frequency.

[0011] Furthermore, after determining to execute the heating oil return mode, the method also includes: after the operating time of the heating oil return mode reaches the preset oil return time, controlling the multi-split system to resume normal heating mode operation; after an interval of a first preset cycle length, triggering the detection of the outdoor ambient temperature and / or the indoor unit startup load rate again, and determining to execute the heating oil return mode or the cooling oil return mode according to the outdoor ambient temperature and / or the indoor unit startup load rate.

[0012] Furthermore, determining to execute the refrigeration oil return mode includes: controlling the multi-split system to switch to the refrigeration mode, controlling the fans of all indoor units to stop running, controlling the flow control valves of all indoor units to be adjusted to a preset maximum opening, and controlling the compressor to maintain operation at a preset high frequency.

[0013] Furthermore, after determining to execute the refrigeration oil return mode, the method also includes: after the operating time of the refrigeration oil return mode reaches the preset oil return time, controlling the multi-split system to resume normal heating mode operation; after an interval of a second preset cycle length, triggering the detection of the outdoor ambient temperature and / or the indoor unit startup load rate again, and determining to execute the heating oil return mode or the refrigeration oil return mode according to the outdoor ambient temperature and / or the indoor unit startup load rate.

[0014] Furthermore, after determining to execute the heating oil return mode, the method also includes: during the execution of the heating oil return mode, detecting the exhaust pressure of the compressor; if the exhaust pressure reaches a preset pressure upper limit, switching to the cooling oil return mode; if the exhaust pressure does not reach the preset pressure upper limit, continuing to maintain the heating oil return mode.

[0015] The present invention also provides an oil return control device for a multi-split system, wherein the device includes: a detection module for detecting the outdoor ambient temperature and / or the indoor unit startup load rate when oil return is required in the heating mode of the multi-split system; a control module for determining whether to execute the heating oil return mode or the cooling oil return mode based on the outdoor ambient temperature and / or the indoor unit startup load rate.

[0016] The present invention also provides a multi-split system, wherein the multi-split system at least includes the above-mentioned multi-split system oil return control device.

[0017] The present invention also provides a computer-readable storage medium having a computer program stored thereon, wherein the program implements the above method when executed by a processor.

[0018] By applying the technical solution of the present invention, different oil return control methods are selected according to the outdoor ambient temperature and / or the indoor unit startup load rate. When the outdoor ambient temperature is low and the indoor unit startup load rate is high, oil return is selected in the heating mode without switching to the cooling mode, thereby avoiding affecting the indoor heating effect and ensuring the user experience of the multi-split system during oil return. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a flow chart of a multi-split system oil return control method according to an embodiment of the present invention;

[0020] Figure 2 is a flow chart of an oil return control method based on outdoor ambient temperature according to an embodiment of the present invention;

[0021] Figure 3 is a flow chart of an oil return control method based on an indoor unit startup load rate according to an embodiment of the present invention;

[0022] Figure 4 is a flow chart of oil return control in heating mode according to an embodiment of the present invention;

[0023] Figure 5 is a preferred flow chart of oil return control in heating mode according to an embodiment of the present invention;

[0024] Figure 6 4 is a structural block diagram of an oil return control device for a multi-split system according to an embodiment of the present invention. DETAILED DESCRIPTION

[0025] To make the objectives, technical solutions, and advantages of the present invention more apparent, the present invention will be further described in detail below with reference to the accompanying drawings. It is apparent that the embodiments described are only some, not all, of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort are intended to fall within the scope of protection of the present invention.

[0026] The terms used in the embodiments of the present invention are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The singular forms "a," "an," "the," and "the" used in the embodiments of the present invention and the appended claims are also intended to include plural forms, and unless the context clearly indicates otherwise, "a plurality" generally includes at least two.

[0027] It should be understood that the term "and / or" as used herein is merely a description of the relationship between associated objects, indicating that three possible relationships exist. For example, "A and / or B" can represent: A exists alone, A and B exist simultaneously, or B exists alone. Furthermore, the character " / " in this document generally indicates that the associated objects are in an "or" relationship.

[0028] As used herein, the words "if" and "if" may be interpreted as "at the time of" or "when" or "in response to determining" or "in response to detecting," depending on the context. Similarly, the phrases "if it is determined" or "if (stated condition or event) is detected" may be interpreted as "when it is determined" or "in response to the determination" or "when detecting (stated condition or event)" or "in response to detecting (stated condition or event)," depending on the context.

[0029] It should also be noted that the terms "include," "comprises," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a product or device comprising a series of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such product or device. In the absence of further limitations, an element defined by the phrase "comprises a..." does not exclude the presence of other identical elements in the product or device comprising the element.

[0030] The optional embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0031] Example 1

[0032] Figure 1 FIG. 1 is a flow chart of a multi-connected system oil return control method according to an embodiment of the present invention. Figure 1 As shown, the method includes the following steps (step S101-step S102):

[0033] Step S101 : When the multi-split system operates in heating mode and oil return is required, the outdoor ambient temperature and / or the indoor unit startup load rate are detected.

[0034] Step S102: determining whether to execute a heating oil return mode or a cooling oil return mode according to the outdoor ambient temperature and / or the indoor unit startup load rate.

[0035] This embodiment selects different oil return control modes according to the outdoor ambient temperature and / or the indoor unit startup load rate. When the outdoor ambient temperature is low and the indoor unit startup load rate is high, oil return is selected in the heating mode without switching to the cooling mode, thereby avoiding affecting the indoor heating effect and ensuring the user experience of the multi-split system during oil return.

[0036] In the oil return control scheme of this embodiment, the oil return control mode can be determined based on the outdoor ambient temperature or the indoor unit load rate alone, or based on a combination of the outdoor ambient temperature and the indoor unit load rate.

[0037] Figure 2 FIG. 1 is a flow chart of an oil return control method based on outdoor ambient temperature according to an embodiment of the present invention. Figure 2 As shown, the process includes the following steps (step S201-step S204):

[0038] Step S201 : When the VRF system operates in heating mode and oil return is required, the outdoor ambient temperature is detected.

[0039] Step S202: Compare the outdoor ambient temperature with a preset temperature threshold.

[0040] Step S203: If the outdoor ambient temperature is less than the preset temperature threshold, it is determined to execute the heating oil return mode.

[0041] Step S204: If the outdoor ambient temperature is greater than or equal to the preset temperature threshold, it is determined to execute the cooling oil return mode.

[0042] The above is a technical solution for judging the oil return control method based on the outdoor ambient temperature. The above preset temperature threshold is a preset value and can be adjusted according to actual needs. During the oil return process, the compressor needs to run at a high frequency. When the outdoor ambient temperature is high, the oil return during heating operation will cause the system pressure to be high, which can easily trigger the compressor to reduce frequency, exit the oil return early, or even high-pressure protection, affecting the oil return effect. The oil return system pressure during cooling operation is relatively low and will not trigger the compressor frequency limit or high-pressure protection. It can ensure that the compressor runs stably at a high frequency during the oil return process and ensure the oil return effect. Therefore, the cooling oil return mode is adopted when the outdoor ambient temperature is high. In addition, when the outdoor ambient temperature is high, the cooling oil return mode will not have much impact on the indoor heating effect.

[0043] Figure 3 FIG. 1 is a flow chart of an oil return control method based on the indoor unit startup load rate according to an embodiment of the present invention. Figure 3 As shown, the process includes the following steps (step S301-step S304):

[0044] In step S301, when the multi-split system is operating in heating mode and requires oil return, the indoor unit startup load rate is detected. Specifically, the rated capacity of the currently active indoor unit and the total rated capacity of the multi-split system are obtained; the indoor unit startup load rate is calculated based on the rated capacity of the active indoor unit and the total rated capacity.

[0045] Step S302: Compare the indoor unit startup load rate with a preset load rate threshold.

[0046] Step S303: If the indoor unit startup load rate is less than the preset load rate threshold, it is determined to execute the cooling oil return mode.

[0047] Step S304: If the indoor unit startup load rate is greater than or equal to the preset load rate threshold, it is determined to execute the heating oil return mode.

[0048] The above is a technical solution for determining the oil return control method based on the indoor unit's power-on load rate. The preset load rate threshold is a preset value and can be adjusted according to actual needs. During heating operation and oil return, the fan of the powered-on indoor unit remains on, and its heat exchanger serves as the system's condenser. During the oil return process, the compressor needs to operate at a high frequency. When the indoor unit's power-on load rate is low, the smaller the condenser in the system, the higher the system's high pressure will be, which can easily trigger compressor frequency limiting, premature oil return exit, or even high-pressure protection, affecting the oil return effect. In cooling mode, however, the oil return system pressure is lower and will not trigger compressor frequency limiting or high-pressure protection. This ensures stable high-frequency operation of the compressor during the oil return process, guaranteeing effective oil return. Therefore, the cooling oil return mode is adopted when the indoor unit's power-on load rate is low. In addition, when the indoor unit's power-on load rate is low, the cooling oil return mode will not significantly affect the indoor heating effect.

[0049] The technical solutions for determining the oil return control mode based solely on the outdoor ambient temperature or the indoor unit startup load rate have been introduced above in conjunction with the accompanying drawings. The technical solution for determining the oil return control mode based on the outdoor ambient temperature and the indoor unit startup load rate will be introduced below. In this technical solution, multiple temperature intervals and multiple load rate intervals are preset, as well as a preset correspondence between each temperature interval, each load rate interval and the oil return mode; the oil return mode includes a heating oil return mode and a cooling oil return mode. After detecting the outdoor ambient temperature and the indoor unit startup load rate, the temperature interval in which the outdoor ambient temperature is located can be determined, as can the load rate interval in which the indoor unit startup load rate is located; then, based on the above correspondence, the oil return mode corresponding to the temperature interval and the load rate interval is determined.

[0050] After determining to execute the heating oil return mode or the cooling oil return mode, the specific operations of the above two oil return modes are introduced below.

[0051] Determining execution of the heating oil return mode includes: controlling the multi-split system to maintain operation in the heating mode, controlling the flow control valves of all indoor units (for example, the flow control valves may be electronic expansion valves) to adjust to a preset maximum opening, and controlling the compressor to maintain operation at a preset high frequency. After the operation time in the heating oil return mode reaches a preset oil return time, controlling the multi-split system to return to normal heating mode operation; after an interval of a first preset period, triggering detection of the outdoor ambient temperature and / or the indoor unit power-on load rate again, and determining execution of the heating oil return mode or the cooling oil return mode based on the outdoor ambient temperature and / or the indoor unit power-on load rate.

[0052] Determine to execute the refrigeration oil return mode, including: controlling the multi-split system to switch to the refrigeration mode, controlling the fans of all indoor units to stop running, controlling the flow control valves of all indoor units to be adjusted to the preset maximum opening, and controlling the compressor to maintain the preset high frequency operation. After the running time of the refrigeration oil return mode reaches the preset oil return time, control the multi-split system to return to the normal heating mode operation; after an interval of the second preset cycle length, trigger the detection of the outdoor ambient temperature and / or the indoor unit startup load rate again, and determine to execute the heating oil return mode or the refrigeration oil return mode according to the outdoor ambient temperature and / or the indoor unit startup load rate. The above-mentioned second preset cycle length ≥ the first preset cycle length. Based on this, a complete and effective oil return operation can be achieved, while avoiding affecting the indoor heating effect and ensuring the user experience of the multi-split system during oil return, while ensuring the system oil return effect.

[0053] Furthermore, taking into account the system pressure limit, the present application detects the compressor exhaust pressure during the heating oil return mode. If the exhaust pressure reaches the preset pressure limit, the system switches to the cooling oil return mode. If the exhaust pressure does not reach the preset pressure limit, the system continues to maintain the heating oil return mode. In other words, when the exhaust pressure reaches the preset pressure limit, the system switches to the cooling mode and executes the cooling oil return mode. This prevents the heating oil return operation from being affected by high-pressure frequency reduction or high-pressure protection shutdown, thereby ensuring safe system operation.

[0054] Example 2

[0055] Figure 4 is an oil return control flow chart in the heating mode according to an embodiment of the present invention, as shown in FIG. Figure 4 As shown, the process includes the following steps (step S401-step S405):

[0056] In step S401, the VRF system requires oil return when operating in heating mode. Whether oil return is necessary can be determined based on the time since the last oil return, for example, by setting an oil return interval. Alternatively, the need for oil return can be determined when system operating parameters meet preset conditions.

[0057] Step S402: Detect the outdoor ambient temperature and the indoor unit power-on load rate. The indoor unit power-on load rate can be calculated by the following preferred implementation: obtain the rated capacity of the currently running indoor units and the total rated capacity of the multi-split system, and calculate the indoor unit power-on load rate based on the rated capacity of the currently running indoor units and the total rated capacity.

[0058] In step S403, the oil return control mode to be executed is determined based on the outdoor ambient temperature and the indoor unit load rate. Oil return control modes include oil return control 1 (heating oil return mode) and oil return control 2 (cooling oil return mode). If oil return control 1 is selected, step S404 is executed; if oil return control 2 is selected, step S405 is executed.

[0059] To determine the oil return control mode, multiple temperature ranges and load rate ranges can be pre-set, and the corresponding relationship between each temperature range and each load rate range and the oil return mode can be preset. Table 1 shows the corresponding relationship between temperature ranges, load rate ranges, and oil return control modes. Here, T refers to the outdoor ambient temperature, and X refers to the indoor unit's operating load rate.

[0060] Table 1

[0061] X<X1 X1≤X<X2 X2≤X<X3 X≥X3 T<T1 Oil return control 1 Oil return control 1 Oil return control 1 Oil return control 1 T1≤T<T2 Oil return control 2 Oil return control 1 Oil return control 1 Oil return control 1 T2≤T<T3 Oil return control 2 Oil return control 2 Oil return control 1 Oil return control 1 T≥T3 Oil return control 2 Oil return control 2 Oil return control 2 Oil return control 1

[0062] The above T1, T2, T3 and X1, X2, X3 are preset values, and satisfy T1<T2<T3, X1<X2<X3. The specific interval division can be refined according to control needs.

[0063] Step S404, oil return control 1 (heating oil return mode): The multi-split system maintains heating mode operation, the electronic expansion valves of all indoor units (all powered-on and powered-off indoor units) are adjusted to the preset maximum opening, and the compressor is controlled to maintain operation at a preset high frequency (maximum frequency or a higher set frequency).

[0064] After the oil return operation time reaches the preset oil return time, all indoor unit electronic expansion valves and outdoor unit compressors adjust to the state before the oil return and continue to operate, that is, return to normal heating mode. After the multi-split system has accumulated t1 time (the first preset cycle time), it enters oil return operation again and re-determines the oil return control mode, where t1 is the preset value.

[0065] Step S405, oil return control 2 (refrigeration oil return mode): the multi-split system switches to cooling mode, controls the fans of all indoor units to stop running, controls the electronic expansion valves of all indoor units to adjust to the preset maximum opening, and controls the compressor to maintain running at a preset high frequency (maximum frequency or a higher set frequency).

[0066] After the oil return operation time reaches the preset oil return time, the multi-split system switches back to heating mode, and both the indoor and outdoor units resume normal operation. After the multi-split system has accumulated t2 time (the second preset cycle length), it enters oil return operation again and re-determines the oil return control mode, where t2 is a preset value and t2 ≥ t1.

[0067] Under the oil return control method of this embodiment, when the outdoor ambient temperature is low and the indoor unit load factor is high, high-frequency heating operation for oil return is less likely to cause excessive system pressure. Furthermore, high indoor heating efficiency is required at this time, so heating mode is used for oil return. Because the indoor unit can continuously heat, a higher oil return frequency can be used to improve compressor reliability. When the outdoor ambient temperature is high and the indoor unit load factor is low, high-frequency heating operation is more likely to cause excessive pressure, preventing the compressor from operating at high frequency and affecting oil return efficiency. Furthermore, low indoor unit heating efficiency is required at this time, so cooling mode is switched to perform oil return.

[0068] Figure 5 FIG. 1 is a preferred flow chart of oil return control in heating mode according to an embodiment of the present invention. Figure 5 As shown, the process includes the following steps:

[0069] Step S501: When the VRF system operates in heating mode, oil return is required.

[0070] Step S502: Detect the outdoor ambient temperature and the indoor unit startup load rate.

[0071] Step S503: Determine the oil return control mode to be executed based on the outdoor ambient temperature and the indoor unit startup load rate. If it is determined to be the heating oil return mode, execute step S504; if it is determined to be the cooling oil return mode, execute step S505.

[0072] Step S504: Execute the heating oil return mode. Then, the compressor exhaust pressure is detected in real time. If the exhaust pressure reaches the preset upper pressure limit, the system switches to the cooling oil return mode. If the exhaust pressure does not reach the preset upper pressure limit, the system continues to maintain the heating oil return mode.

[0073] Step S505: executing the refrigeration oil return mode.

[0074] This embodiment selects different oil return control modes according to the outdoor ambient temperature and the indoor unit startup load rate. It can select oil return in heating mode when the outdoor ambient temperature is low and the indoor unit startup load rate is high, without switching to cooling mode, thereby avoiding affecting the indoor heating effect and ensuring the user experience of the multi-split system during oil return. It can also monitor the exhaust pressure in real time, and switch to cooling mode in time when the exhaust pressure reaches the preset pressure upper limit, execute the cooling oil return mode, reduce the system exhaust pressure, and ensure the safe operation of the system.

[0075] Example 3

[0076] Corresponding to Figure 1 The oil return control method of the multi-split system is introduced. This embodiment provides an oil return control device for a multi-split system, such as Figure 6 The structural block diagram of the multi-split system oil return control device shown in FIG. 1 includes:

[0077] The detection module 10 is used to detect the outdoor ambient temperature and / or the indoor unit startup load rate when the multi-split system is operating in heating mode and oil return is required;

[0078] The control module 20 is connected to the detection module 10 and is used to determine whether to execute the heating oil return mode or the cooling oil return mode according to the outdoor ambient temperature and / or the indoor unit startup load rate.

[0079] This embodiment enables the selection of different oil return control modes based on the outdoor ambient temperature and / or the indoor unit load rate. When the outdoor ambient temperature is low and the indoor unit load rate is high, oil return is selected in heating mode without switching to cooling mode, thus avoiding impacting the indoor heating effect and ensuring a good user experience during oil return in the VRF system. The control logic for this implementation has been previously described and will not be repeated here.

[0080] This embodiment further provides a multi-split system, wherein the multi-split system at least includes the above-mentioned multi-split system oil return control device.

[0081] Example 4

[0082] An embodiment of the present invention provides a software for executing the technical solutions described in the above embodiment and preferred implementation manner.

[0083] An embodiment of the present invention provides a non-volatile computer storage medium storing computer executable instructions. The computer executable instructions can execute the multi-split system oil return control method in any of the above method embodiments.

[0084] The above-mentioned software is stored in the above-mentioned storage medium, which includes but is not limited to: a CD, a floppy disk, a hard disk, a rewritable memory, etc.

[0085] The above-mentioned product can execute the method provided by the embodiment of the present invention, and has the functional modules and beneficial effects corresponding to the execution method. For technical details not fully described in this embodiment, please refer to the method provided by the embodiment of the present invention.

[0086] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of the modules may be selected based on actual needs to achieve the objectives of this embodiment.

[0087] Through the description of the above embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus a necessary general hardware platform, or of course, by hardware. Based on this understanding, the essence of the above technical solution or the part that contributes to the existing technology can be embodied in the form of a software product. The computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, a magnetic disk, an optical disk, etc., and includes a number of instructions for enabling a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment or certain parts of the embodiments.

[0088] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A multi-connected system oil return control method, characterized in that: The method comprises: When oil return is required in the multi-split system operating in heating mode, the outdoor ambient temperature and / or the indoor unit startup load rate are detected; determining whether to execute a heating oil return mode or a cooling oil return mode according to the outdoor ambient temperature and / or the indoor unit startup load rate; Among them, according to the outdoor ambient temperature and the indoor unit startup load rate, determining whether to execute the heating oil return mode or the cooling oil return mode includes: determining the temperature range in which the outdoor ambient temperature is located, and determining the load rate range in which the indoor unit startup load rate is located; wherein, multiple temperature ranges and multiple load rate ranges are preset, and a corresponding relationship between each temperature range, each load rate range and the oil return mode is preset; according to the corresponding relationship, determining the oil return mode corresponding to the temperature range and the load rate range; wherein, the oil return mode includes the heating oil return mode and the cooling oil return mode.

2. The method according to claim 1, characterized in that Detect the indoor unit power-on load rate, including: Obtain the rated capacity of the currently running internal units and the total rated capacity of the multi-connected system; The startup load rate of the indoor unit is calculated according to the startup indoor unit rated capacity and the total rated capacity.

3. The method according to claim 1, characterized in that Determining whether to execute a heating oil return mode or a cooling oil return mode according to the outdoor ambient temperature includes: comparing the outdoor ambient temperature with a preset temperature threshold; If the outdoor ambient temperature is less than the preset temperature threshold, determining to execute the heating oil return mode; If the outdoor ambient temperature is greater than or equal to the preset temperature threshold, it is determined to execute the cooling oil return mode.

4. The method according to claim 1, wherein Determining whether to execute a heating oil return mode or a cooling oil return mode according to the indoor unit startup load rate includes: Comparing the indoor unit startup load rate with a preset load rate threshold; If the indoor unit startup load rate is less than the preset load rate threshold, determining to execute the cooling oil return mode; If the indoor unit startup load rate is greater than or equal to the preset load rate threshold, it is determined to execute the heating oil return mode.

5. The method according to claim 1, wherein Determine the execution of heating oil return mode, including: The multi-split system is controlled to operate in the heating mode, the flow control valves of all indoor units are controlled to be adjusted to a preset maximum opening, and the compressor is controlled to operate at a preset high frequency.

6. The method according to claim 1, characterized in that After determining to execute the heating oil return mode, the method further includes: After the operation time of the heating oil return mode reaches the preset oil return time, controlling the multi-split system to return to the normal heating mode operation; After the first preset period, the outdoor ambient temperature and / or the indoor unit startup load rate are triggered again to detect the outdoor ambient temperature and / or the indoor unit startup load rate, and the heating oil return mode or the cooling oil return mode is determined to be executed according to the outdoor ambient temperature and / or the indoor unit startup load rate.

7. The method according to claim 1, characterized in that Determine the execution of refrigeration oil return mode, including: The multi-split system is controlled to switch to cooling mode, the fans of all indoor units are controlled to stop running, the flow control valves of all indoor units are controlled to be adjusted to a preset maximum opening, and the compressor is controlled to maintain running at a preset high frequency.

8. The method according to claim 1, characterized in that After determining to execute the refrigeration oil return mode, the method further includes: After the running time of the cooling oil return mode reaches the preset oil return time, controlling the multi-split system to return to the normal heating mode; After a second preset period, the outdoor ambient temperature and / or the indoor unit startup load rate are triggered again to detect the outdoor ambient temperature and / or the indoor unit startup load rate, and the heating oil return mode or the cooling oil return mode is determined to be executed according to the outdoor ambient temperature and / or the indoor unit startup load rate.

9. The method according to any one of claims 1 to 8, characterized in that After determining to execute the heating oil return mode, the method further includes: During the execution of the heating oil return mode, detecting the exhaust pressure of the compressor; If the exhaust pressure reaches a preset upper pressure limit, switching to the refrigeration oil return mode; If the exhaust pressure does not reach the preset upper pressure limit, the heating oil return mode is maintained.

10. A multi-split system oil return control device, used to implement the multi-split system oil return control method according to any one of claims 1 to 9, characterized in that: The device comprises: A detection module is used to detect the outdoor ambient temperature and / or the indoor unit startup load rate when oil return is required in the multi-split system operating in heating mode; The control module is used to determine whether to execute a heating oil return mode or a cooling oil return mode according to the outdoor ambient temperature and / or the indoor unit startup load rate.

11. A multi-connection system, characterized in that: The multi-split system at least includes: the multi-split system oil return control device according to claim 10.

12. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the method according to any one of claims 1 to 9 is implemented.

Images