Air conditioning system, its oil return control method and device, and computer-readable storage medium

Abstract

The present invention discloses an air conditioning system, its oil return control method and device, and a computer-readable storage medium. The air conditioning system includes a compressor, a four-way valve, an outdoor heat exchanger, a first throttling component, a second throttling component, and an indoor heat exchanger that are interconnected to form a refrigerant circulation circuit. The refrigerant circulation circuit further includes a bypass pipeline connected in parallel with the first throttling component, and a control valve is provided on the bypass pipeline. The air conditioning system has a normal operation state and a forced oil return state. In the normal operation state, the control valve is opened to conduct the bypass pipeline, and in the forced oil return state, the control valve is closed to cut off the bypass pipeline. The technical solution of the present invention can achieve effective oil return of the compressor and improve the operation reliability of the compressor and the air conditioning system.

Description

Technical Field

[0001] The present invention relates to the technical field of air conditioners, and particularly to an air conditioning system, an oil return control method and device thereof, and a computer-readable storage medium. Background Art

[0002] The compressor is the core power component of the air conditioning system. Compared with ordinary compressors, the liquid storage tank integrated with the compressor is located at the bottom of the compressor, with a smaller overall size and less occupied space, which is more conducive to the miniaturization development of air conditioners. However, this type of integrated compressor also has certain drawbacks. Since the liquid storage tank is arranged at the bottom of the pump body and is connected to the pump body through an oil return pipe, during oil return, the oil in the liquid storage tank is pumped through the suction and discharge force of the compressor into the oil sump of the upper pump body via the oil return pipe. There is a certain resistance in the entire oil return process, resulting in ineffective oil return to the compressor, which causes insufficient lubrication of the compressor and ultimately leads to compressor damage, and is not conducive to the operation reliability of the compressor and the air conditioning system. Summary of the Invention

[0003] The main object of the present invention is to propose an air conditioning system, aiming to achieve effective oil return of the compressor and improve the operation reliability of the compressor and the air conditioning system.

[0004] To achieve the above object, the air conditioning system proposed by the present invention includes a compressor, a four-way valve, an outdoor heat exchanger, a first throttling component, a second throttling component, and an indoor heat exchanger that are interconnected to form a refrigerant circulation loop. The refrigerant circulation loop further includes a bypass pipeline connected in parallel with the first throttling component, and a control valve is provided on the bypass pipeline. The air conditioning system has a normal operation state and a forced oil return state. In the normal operation state, the control valve is opened to conduct the bypass pipeline. In the forced oil return state, the control valve is closed to cut off the bypass pipeline.

[0005] In one embodiment, the throttling flow rate of the first throttling component is less than the throttling flow rate of the second throttling component.

[0006] In one embodiment, the throttling flow rate of the first throttling component is Q1, and the throttling flow rate of the second throttling component is Q2, where Q1 ≤ 0.5Q2.

[0007] In one embodiment, the compressor includes a pump body and a liquid storage tank provided on the lower side of the pump body. The liquid storage tank is communicated with the pump body through an oil return pipe. The pump body is provided with an exhaust port, and the liquid storage tank is provided with a return air port. The exhaust port and the return air port are respectively communicated with the four-way valve through pipelines.

[0008] The present invention also proposes an oil return control method for an air conditioning system, which is used for the air conditioning system as described above. The oil return control method of the air conditioning system includes the following steps:

[0009] Detect the operating mode of the current air conditioning system;

[0010] Judge whether to perform oil return operation detection according to the operating mode;

[0011] When the operating mode is the refrigeration mode or the dehumidification mode, perform oil return operation detection;

[0012] When the operating mode is a non - refrigeration mode or a non - dehumidification mode, do not perform oil return operation detection;

[0013] Obtain the operating state of the compressor when performing oil return operation detection;

[0014] Judge whether the forced oil return condition is satisfied according to the operating state of the compressor;

[0015] When the forced oil return condition is satisfied, control the compressor to adjust to operate at a preset oil return frequency;

[0016] Close the control valve.

[0017] In one embodiment, the step of performing oil return operation detection to obtain the operating state of the compressor includes:

[0018] Obtain the current operating frequency Fr and the cumulative operating duration T of the compressor.

[0019] In one embodiment, the step of judging whether the forced oil return condition is satisfied according to the operating state of the compressor includes:

[0020] When the current operating frequency Fr of the compressor is less than the first preset frequency Fr1 and the cumulative operating duration T of the compressor is greater than the first preset duration T1, it is determined that the forced oil return condition is satisfied;

[0021] When the current operating frequency Fr of the compressor is greater than the first preset frequency Fr1 and the cumulative operating duration T of the compressor is greater than the second preset duration T2, it is determined that the forced oil return condition is satisfied, where the second preset duration T2 is greater than the first preset duration T1.

[0022] In one embodiment, the step of controlling the compressor to adjust to operate at a preset oil return frequency when the forced oil return condition is satisfied includes:

[0023] When the current operating frequency Fr of the compressor is less than the preset oil return frequency Frh, raise the operating frequency of the compressor to the preset oil return frequency Frh;

[0024] When the current operating frequency Fr of the compressor is greater than the preset oil return frequency Frh, the operating frequency of the compressor is reduced to the preset oil return frequency Frh.

[0025] In one embodiment, after the step of when the current operating frequency Fr of the compressor is greater than the preset oil return frequency Frh, and the operating frequency of the compressor is reduced to the preset oil return frequency Frh, and before the step of closing the control valve, the following steps are further included:

[0026] Control the compressor to operate at the preset oil return frequency for a third preset duration.

[0027] In one embodiment, after the step of closing the control valve, the following steps are further included:

[0028] Obtain the cumulative closing duration of the control valve;

[0029] When the cumulative closing duration of the control valve reaches the fourth preset duration, open the control valve and control the compressor to resume operating at the operating frequency before the oil return operation.

[0030] The present invention also provides a control device for an air conditioning system, for the air conditioning system as described above. The control device of the air conditioning system includes:

[0031] A mode detection module, configured to detect the operating mode of the air conditioning system;

[0032] A first judgment module, configured to judge whether to perform an oil return operation detection according to the operating mode;

[0033] A status detection module, configured to obtain the operating status of the compressor when performing the oil return operation detection;

[0034] A second judgment module, configured to judge whether the forced oil return condition is satisfied according to the operating status of the compressor;

[0035] A control module, configured to control the compressor to adjust to operate at the preset oil return frequency and control to close the control valve when the forced oil return condition is satisfied.

[0036] In one embodiment, the status detection module includes:

[0037] A first acquisition unit, configured to acquire the current operating frequency Fr of the compressor;

[0038] A second acquisition unit, configured to acquire the cumulative operating duration T of the compressor.

[0039] In one embodiment, the second judgment module includes:

[0040] A first determination unit, configured to determine that the forced oil return condition is satisfied when the current operating frequency Fr of the compressor is less than a first preset frequency Fr1 and the cumulative operating duration T of the compressor is greater than a first preset duration T1;

[0041] A second determination unit, configured to determine that the forced oil return condition is satisfied when the current operating frequency Fr of the compressor is greater than the first preset frequency Fr1 and the cumulative operating duration T of the compressor is greater than a second preset duration T2, where the second preset duration T2 is greater than the first preset duration T1.

[0042] In one embodiment, the control module includes an adjustment unit, and the adjustment unit is configured to increase the operating frequency of the compressor to a preset oil return frequency Frh when the current operating frequency Fr of the compressor is less than the preset oil return frequency Frh; the adjustment unit is further configured to decrease the operating frequency of the compressor to the preset oil return frequency Frh when the current operating frequency Fr of the compressor is greater than the preset oil return frequency Frh.

[0043] In one embodiment, the control device of the air-conditioning system further includes a first timing module, and the first timing module is configured to obtain the duration of the compressor operating at the preset oil return frequency.

[0044] In one embodiment, the control device of the air-conditioning system further includes a second timing module, and the second timing module is configured to obtain the cumulative closing duration of the control valve. The control module is further configured to open the control valve and control the compressor to operate at the operating frequency before oil return when the cumulative closing duration of the control valve reaches a fourth preset duration.

[0045] The present invention also provides a computer-readable storage medium, on which a control program for an air-conditioning system is stored, and the control program for the air-conditioning system is executed by a processor to perform the steps of the oil return control method for the air-conditioning system as described above.

[0046] The technical solution of the present invention is to provide a first throttling component and a second throttling component on the refrigerant circulation loop of the air-conditioning system, and a bypass pipeline parallel to the first throttling component is provided, and a control valve is provided on the bypass pipeline. When the air-conditioning system is in a normal operating state, the control valve is opened to conduct the bypass pipeline. At this time, the entire refrigerant circulation loop is mainly throttled by the second throttling component to ensure the normal operation of the air-conditioning system. When the compressor needs to return oil, the compressor is adjusted to operate at a preset oil return operating frequency, and the control valve is closed to cut off the bypass pipeline. At this time, the air-conditioning system is in a forced oil return state. In the forced oil return state, the compressor uses its own suction characteristics to pump the oil in the indoor heat exchanger and the outdoor heat exchanger back into the compressor to complete the forced oil return. The first throttling component and the second throttling component are connected in series, and the entire refrigerant circulation loop is throttled by the combined action of the first throttling component and the second throttling component. Through the combined action of the first throttling component and the second throttling component, the pressure at the exhaust port of the compressor is greater, so as to provide a greater driving force for the flow of lubricating oil and refrigerant along the refrigerant circulation loop, and further enable the lubricating oil to flow back to the pump body of the compressor along with the refrigerant circulation loop. The air-conditioning system of the present invention can make the compressor have a better oil return effect during forced oil return, effectively enable the compressor to complete forced oil return, thereby improving the service life of the compressor and enhancing the operation reliability of the compressor and the air-conditioning system. Brief Description of the Drawings

[0047] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on the structures shown in these drawings.

[0048] Figure 1 It is a schematic structural diagram of an embodiment of the air-conditioning system of the present invention;

[0049] Figure 2 It is a schematic module diagram of an embodiment of the control device of the air-conditioning system of the present invention;

[0050] Figure 3 It is a schematic module diagram of another embodiment of the control device of the air-conditioning system of the present invention;

[0051] Figure 4 It is a schematic module diagram of an embodiment of the status detection module;

[0052] Figure 5 It is a schematic module diagram of an embodiment of the second judgment module;

[0053] Figure 6Schematic flowchart of an embodiment of the oil return control method for the air conditioning system of the present invention;

[0054] Figure 7 Schematic flowchart of another embodiment of the oil return control method for the air conditioning system of the present invention;

[0055] Figure 8 Schematic flowchart of yet another embodiment of the oil return control method for the air conditioning system of the present invention.

[0056] Explanation of the reference numerals in the drawings:

[0057] Label Name Label Name 10 Compressor 100 Mode Detection Module 11 Pump Body 200 First Judgment Module 12 Liquid Storage Tank 300 Status Detection Module 13 Return Oil Pipe 310 First Acquisition Unit 20 Four-way Valve 320 Second Acquisition Unit 30 Outdoor Heat Exchanger 400 Second Judgment Module 40 First Throttling Component 410 First Determination Unit 50 Second Throttling Component 420 Second Determination Unit 60 Indoor Heat Exchanger 500 Control Module 70 Bypass Pipeline 600 First Timing Module 80 Control Valve 700 Second Timing Module

[0058] The realization of the object, functional features and advantages of the present invention will be further described with reference to the embodiments and the accompanying drawings. Detailed implementation manners

[0059] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0060] It should be noted that if there are directional indications (such as up, down, left, right, front, back...) involved in the embodiments of the present invention, the directional indications are only used to explain the relative positional relationship and movement conditions between components in a specific posture. If the specific posture changes, the directional indications will also change accordingly.

[0061] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one such feature. In addition, if "and / or" or "and / or" appears throughout the text, its meaning includes three parallel solutions. Taking "A and / or B" as an example, it includes solution A, solution B, or a solution where A and B are satisfied simultaneously. In addition, the technical solutions between the embodiments can be combined with each other, but it must be based on the fact that those of ordinary skill in the art can implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the protection scope required by the present invention.

[0062] The present invention provides an air conditioning system.

[0063] Please refer to Figure 1, in an embodiment of the present invention, the air-conditioning system includes a compressor 10, a four-way valve 20, an outdoor heat exchanger 30, a first throttling component 40, a second throttling component 50, and an indoor heat exchanger 60 that are interconnected to form a refrigerant circulation loop. The refrigerant circulation loop further includes a bypass pipeline 70 that is connected in parallel with the first throttling component 40. The bypass pipeline 70 is provided with a control valve 80. The air-conditioning system has a normal operation state and a forced oil return state. In the normal operation state, the control valve 80 is opened to conduct the bypass pipeline 70. In the forced oil return state, the control valve 80 is closed to cut off the bypass pipeline 70.

[0064] Specifically, the air-conditioning system includes a compressor 10, a four-way valve 20, an outdoor heat exchanger 30 (such as a condenser), a first throttling component 40, a second throttling component 50, and an indoor heat exchanger 60 (such as a heat exchanger) that are interconnected and form a refrigerant circulation loop. The four-way valve 20 has a first port, a second port, a third port, and a fourth port. The compressor 10 includes an exhaust port provided on the pump body 11 and a suction port provided on the liquid storage tank 12. The first port is communicated with the exhaust port through an exhaust pipe, the second port is communicated with the suction port through a suction pipe, the third port is communicated with the outdoor heat exchanger 30, and the fourth port is communicated with the indoor heat exchanger 60. By means of the four-way valve 20, the flow direction of the refrigerant in the refrigerant circulation loop can be changed, so that the air-conditioning system can achieve different function modes. When the first port is communicated with the third port and the second port is communicated with the fourth port, the air-conditioning system realizes a refrigeration function or a dehumidification function. When the first port is communicated with the fourth port and the second port is communicated with the third port, the air-conditioning system realizes a heating function.

[0065] The above refrigerant circulation circuit further includes a bypass pipeline 70 connected in parallel with the first throttling component 40. A control valve 80 is provided on the bypass pipeline 70, and the control valve 80 is used to conduct or cut off the bypass pipeline 70. Specifically, the air-conditioning system has a normal operation state and a forced oil return state. In the normal operation state, the control valve 80 is opened to conduct the bypass pipeline 70. In the forced oil return state, the control valve 80 is closed to cut off the bypass pipeline 70. When the air-conditioning system starts to operate normally initially, the control valve 80 is defaulted to the open state, that is, the bypass pipeline 70 is conducted at this time. Compared with the first throttling component 40, the fluid resistance in the bypass pipeline 70 is smaller. At this time, the refrigerant in the refrigerant circulation circuit bypasses the first throttling component 40 and is directly transported from the bypass pipeline 70 to the second throttling component 50. That is, in the normal operation state of the air conditioner, only the second throttling component 50 plays a major throttling role. When the air-conditioning system is in the forced oil return state, the control valve 80 is closed to cut off the bypass pipeline 70. At this time, the first throttling component 40 and the second throttling component 50 jointly play a throttling role. Among them, the first throttling component 40 and the second throttling component 50 can adopt a capillary tube or an electronic expansion throttle valve, etc. The control valve 80 includes but is not limited to a mechanical valve or a solenoid valve. Optionally, in this embodiment, the control valve 80 adopts a solenoid valve.

[0066] Taking the normal refrigeration mode as an example, in the initial state, the control valve 80 is opened to conduct the bypass pipeline 70. The exhaust port of the compressor 10 is communicated with the input end of the outdoor heat exchanger 30 (condenser) via the four-way valve 20. The output end of the outdoor heat exchanger 30 is communicated with the input end of the indoor heat exchanger 60 (evaporator) via the bypass pipeline 70 and the second throttling component 50. The output end of the indoor heat exchanger 60 is communicated with the suction port of the compressor 10 via the four-way valve 20, thereby forming a refrigerant circulation circuit. In the refrigeration mode, the pump body 11 of the compressor 10 compresses the refrigerant into a high-temperature and high-pressure gaseous refrigerant and transports it to the outdoor heat exchanger 30 via the exhaust pipeline. In the outdoor heat exchanger 30, the refrigerant is liquefied and cooled to form a medium-temperature and high-pressure liquid refrigerant. The medium-temperature and high-pressure liquid refrigerant forms a low-temperature and low-pressure liquid refrigerant after passing through the second throttling component 50 and is transported to the indoor heat exchanger 60. In the indoor heat exchanger 60, the refrigerant evaporates and absorbs heat to form a low-temperature and low-pressure gaseous refrigerant, and then the low-temperature and low-pressure gaseous refrigerant is transported to the liquid storage tank 12 via the suction port, thus forming a circulation cycle. The working principle of the air-conditioning system is well-known to those skilled in the art and will not be elaborated here. The working principle of the air-conditioning system is well-known to those skilled in the art and will not be elaborated here.

[0067] When the air-conditioning system operates for a long time, the lubricating oil of the compressor 10 will circulate in the refrigerant circulation circuit together with the refrigerant. If the compressor 10 operates at a low frequency for a long time, it will cause the lubricating oil to accumulate in the pipes of the refrigerant circulation circuit. Especially when the integrated compressor 10 is used, the liquid storage tank 12 is located below the pump body 11, and the liquid storage tank 12 and the pump body 11 are connected by a return oil pipe 13. Since the liquid storage tank 12 is arranged at the bottom of the pump body 11 and the liquid storage tank 12 and the pump body 11 are connected by the return oil pipe 13, during oil return, the suction and discharge force of the compressor 10 sucks the oil in the liquid storage tank 12 into the oil sump of the upper pump body 11 through the return oil pipe 13. There is a certain resistance in the whole oil return process, resulting in the oil not being able to effectively return to the compressor 10, thus causing insufficient lubrication of the compressor 10 and ultimately leading to the damage of the compressor 10, which is not conducive to the operation reliability of the compressor 10 and the air-conditioning system. Therefore, after the air-conditioning system operates for a period of time, it is necessary to switch the air-conditioning system from the normal operation state to the forced oil return state for oil return.

[0068] The technical solution of the present invention is to set a first throttling component 40 and a second throttling component 50 on the refrigerant circulation circuit of the air-conditioning system, and set a bypass pipeline 70 in parallel with the first throttling component 40, and a control valve 80 is arranged on the bypass pipeline 70. When the air-conditioning system is in the normal operation state, the control valve 80 is opened to conduct the bypass pipeline 70. At this time, the whole refrigerant circulation circuit is mainly throttled by the second throttling component 50 to ensure the normal operation of the air-conditioning system. When the compressor 10 needs to return oil, the compressor 10 is adjusted to operate at a preset oil return operation frequency, and the control valve 80 is closed to cut off the bypass pipeline 70. At this time, the air-conditioning system is in the forced oil return state. In the forced oil return state, the compressor 10 uses its own suction characteristics to suck the oil in the indoor heat exchanger 60 and the outdoor heat exchanger 30 back into the compressor 10 to complete the forced oil return. The first throttling component 40 and the second throttling component 50 are connected in series, and the whole refrigerant circulation circuit is throttled by the combined action of the first throttling component 40 and the second throttling component 50. Through the combined action of the first throttling component 40 and the second throttling component 50, the pressure at the exhaust port of the compressor 10 is greater, so as to provide a greater driving force for the flow of the lubricating oil and the refrigerant along the refrigerant circulation circuit, and further enable the lubricating oil to flow back to the pump body 11 of the compressor 10 along the refrigerant circulation circuit. The air-conditioning system of the present invention can make the compressor 10 have a better oil return effect during forced oil return, effectively enable the compressor 10 to complete forced oil return, thereby improving the service life of the compressor 10 and the operation reliability of the compressor 10 and the air-conditioning system.

[0069] In one embodiment, the throttling flow rate of the first throttling component 40 is less than that of the second throttling component 50. When the air-conditioning system operates normally, the second throttling component 50 plays a major throttling role, and the throttling flow rate of the second throttling component 50 is relatively large, which can ensure the normal operation of the air-conditioning system. When the air-conditioning system performs forced oil return, the first throttling component 40 and the second throttling component 50 act together to achieve a better oil return effect. Optionally, the throttling flow rate of the first throttling component 40 is Q1, and the throttling flow rate of the second throttling component 50 is Q2, where Q1 ≤ 0.5Q2.

[0070] In order to achieve the miniaturization development of the air-conditioning system, in one embodiment, the compressor 10 specifically relates to an integrated compressor 10. Please refer to Figure 1 , the compressor 10 includes a pump body 11 and a liquid storage tank 12 provided on the lower side of the pump body 11. The liquid storage tank 12 is communicated with the pump body 11 through an oil return pipe 13. The pump body 11 is provided with an exhaust port, and the liquid storage tank 12 is provided with a return air port. The exhaust port and the return air port are respectively communicated with the four-way valve 20 through pipelines.

[0071] Specifically, the compressor 10 is an integrated compressor 10 in which the pump body 11 and the liquid storage tank 12 are integrated. The overall structure is compact and occupies a small space, which can be well applied to the miniaturization development of the compressor 10 and the air-conditioning outdoor unit. Among them, the pump body 11 is the core power component. An oil pool is provided inside the pump body 11, and the oil pool is generally provided at the bottom of the pump body 11. Correspondingly, the liquid storage tank 12 is provided below the pump body 11. A sandwich layer can be provided between the pump body 11 and the liquid storage tank 12, for example, a hollow sandwich layer can be provided. By providing a sandwich layer between the pump body 11 and the liquid storage tank 12, a certain heat insulation effect can be achieved to avoid heat exchange between the low temperature of the liquid storage tank 12 and the oil in the oil pool in the pump body 11, resulting in a decrease in the oil temperature in the oil pool. An exhaust port is provided at the top of the pump body 11, and the exhaust port is communicated with the first port of the four-way valve 20 through an exhaust pipe. A return air port is provided on the side of the liquid storage tank 12, and the return air port is communicated with the second port of the four-way valve 20 through a return air pipe. The liquid storage tank 12 and the side of the pump body 11 are communicated through an oil return pipe 13. The high-temperature and high-pressure refrigerant generated in the pump body 11 is output through the exhaust port and flows along the refrigerant circulation circuit, and finally returns to the liquid storage tank 12 through the return air port. While the refrigerant is being transported, the lubricating oil in the oil pool of the pump body 11 also flows along the refrigerant circulation circuit and finally returns to the liquid storage tank 12. Under the suction and discharge force of the compressor 10, the refrigerant and lubricating oil in the liquid storage tank 12 can return to the pump body 11 through the oil return pipe 13, and so on in a cycle to ensure the normal operation of the compressor 10 and the air-conditioning system. Optionally, a filter is further provided in the return air pipe. The filter can filter impurities in the refrigerant and lubricating oil to prevent impurities from entering the compressor 10 and causing damage to the compressor 10.

[0072] Based on the above air-conditioning system, the present invention further proposes an oil return control method for the air-conditioning system.

[0073] Please refer to Figure 6 In one embodiment of the present invention, the oil return control method of the air conditioning system comprises the following steps:

[0074] S1, detecting the current operating mode of the air conditioning system;

[0075] S2. judging whether to perform oil return operation detection according to the operation mode;

[0076] When the operation mode is a cooling mode or a dehumidification mode, performing an oil return operation detection;

[0077] When the operation mode is a non-refrigeration mode or a non-dehumidification mode, the oil return operation detection is not performed;

[0078] S3, obtaining the operating state of the compressor 10 when performing the oil return operation detection;

[0079] S4, judging whether the forced oil return condition is met according to the operating state of the compressor 10;

[0080] S5. When the forced oil return condition is met, the compressor 10 is controlled to operate at a preset oil return frequency;

[0081] S6. Close the control valve 80.

[0082] Specifically, the air conditioning system implements the oil return control method of the air conditioning system through the control device of the air conditioning system. Figure 1 and Figure 2 The control device of the air conditioning system includes a mode detection module 100, a first judgment module 200, a state detection module 300, a second judgment module 400 and a control module 500. When the air conditioning system is in a normal operating state, the control valve 80 is in an open state, and the bypass line 70 is connected at this time. The air conditioning system mainly plays a throttling role through the second throttling component 50. During the operation of the air conditioning system, the mode detection module 100 is used to detect the operating mode of the air conditioning system, wherein the operating mode of the air conditioning system includes a cooling mode, a dehumidification mode and a heating mode. The mode detection module 100 feeds back the detection result to the first judgment module 200, and then the first judgment module 200 determines whether to perform the oil return operation detection according to the operating mode. When the operating mode is a cooling mode or a dehumidification mode, the first judgment module 200 determines that the oil return operation detection needs to be performed, and at this time, the oil return operation detection can be performed in the next step. When the operating mode is a non-cooling mode or a non-dehumidification mode (for example, the operating mode is a heating mode), the first judgment module 200 determines that the oil return operation detection does not need to be performed, and at this time, the air conditioning system still operates normally in the current mode.

[0083] When the operating mode is the refrigeration mode or the dehumidification mode, an oil return operation detection is performed. During the oil return operation detection, the operating state of the compressor 10 is obtained through the state detection module 300, such as the current operating frequency and the cumulative operating duration of the compressor 10, etc. Then the state detection module 300 feeds back the detection result to the second judgment module 400, and the second judgment module 400 judges whether the compressor 10 needs to meet the forced oil return condition according to the operating state of the compressor 10. If the forced oil return condition is met, it indicates that the compressor 10 needs to perform forced oil return. If the forced oil return condition is not met, it means that the compressor 10 does not need to perform forced oil return at present. The control module 500 receives the judgment result fed back by the second judgment module 400. When the forced oil return condition is met, the control module 500 controls the compressor 10 to adjust to the preset oil return frequency for operation, and controls the closing of the control valve 80, so that the air conditioning system is switched to the forced oil return state. In the forced oil return state, the compressor 10 uses its own suction characteristics to pump the oil in the indoor heat exchanger 60 and the outdoor heat exchanger 30 back into the compressor 10 to complete the forced oil return.

[0084] The above oil return control method of the air conditioning system can judge whether the compressor 10 meets the forced oil return condition, and when the forced oil return condition is met, it can timely control the compressor 10 to adjust to the preset oil return operation frequency for operation, and close the control valve 80 to cut off the bypass pipeline 70, so that the air conditioning system is switched to the forced oil return state. At this time, the first throttling component 40 and the second throttling component 50 are connected in series, and the entire refrigerant circulation loop is throttled through the combined action of the first throttling component 40 and the second throttling component 50. Through the combined action of the first throttling component 40 and the second throttling component 50, the pressure at the exhaust port of the compressor 10 is greater, so as to provide a greater driving force for the lubricating oil and the refrigerant to flow along the refrigerant circulation loop, and further enable the lubricating oil to flow back to the pump body 11 of the compressor 10 along the refrigerant circulation loop. Thus, a better oil return effect can be achieved when the compressor 10 performs forced oil return, the compressor 10 can effectively complete the oil return, thereby improving the service life of the compressor 10 and the operation reliability of the compressor 10 and the air conditioning system.

[0085] In order to more accurately judge the current operating state of the compressor 10, please refer to Figure 8 , in one of the embodiments, the step of performing the oil return operation detection to obtain the operating state of the compressor 10 includes:

[0086] Obtain the current operating frequency Fr and the cumulative operating duration T of the compressor 10.

[0087] Specifically, the status detection module 300 includes a first acquisition unit 310 and a second acquisition unit 320. When the current operating mode of the air conditioning system is the cooling mode or the dehumidification mode, the oil return operation detection is performed. The current operating frequency Fr of the compressor 10 is acquired by the first acquisition unit 310; the cumulative operating duration T of the compressor 10 is acquired by the second acquisition unit 320. Then, the first determination unit determines whether the forced oil return condition is satisfied according to the current operating frequency Fr and the cumulative operating duration T of the compressor 10. Since both the current operating frequency and the cumulative operating duration of the compressor 10 are considered, the actual operating state of the compressor 10 can be more accurately reflected, and reliable data can be provided for determining whether the compressor 10 satisfies the forced oil return condition.

[0088] Further, the step of determining whether the forced oil return condition is satisfied according to the operating state of the compressor 10 includes:

[0089] When the current operating frequency Fr of the compressor 10 is less than the first preset frequency Fr1 and the cumulative operating duration T of the compressor 10 is greater than the first preset duration T1, it is determined that the forced oil return condition is satisfied;

[0090] When the current operating frequency Fr of the compressor 10 is greater than the first preset frequency Fr1 and the cumulative operating duration T of the compressor 10 is greater than the second preset duration T2, it is determined that the forced oil return condition is satisfied, where the second preset duration T2 is greater than the first preset duration T1.

[0091] Specifically, the second judgment module 400 includes a first determination unit 410 and a second determination unit 420. The first determination unit 410 presets, through a built-in program, that the conditions for forced oil return are met when the current operating frequency Fr of the compressor 10 is less than the first preset frequency Fr1 and the cumulative operating duration T of the compressor 10 is greater than the first preset duration T1. The second determination unit 420 presets, through a built-in program, that the conditions for forced oil return are met when the current operating frequency Fr of the compressor 10 is greater than the first preset frequency Fr1 and the cumulative operating duration T of the compressor 10 is greater than the second preset duration T2. After the state detection module 300 obtains the current operating frequency Fr and the cumulative operating duration T of the compressor 10, it feeds the results back to the second judgment module 400. The first determination unit 410 and the second determination unit 420 of the second judgment module 400 judge whether the conditions for forced oil return are met according to different determination conditions. When the current operating frequency Fr of the compressor 10 is less than the first preset frequency Fr1 and the cumulative operating duration T of the compressor 10 is greater than the first preset duration T1, the first determination unit 410 determines that the conditions for forced oil return are met. When the current operating frequency Fr of the compressor 10 is greater than the first preset frequency Fr1 and the cumulative operating duration T of the compressor 10 is greater than the second preset duration T2, the second determination unit 420 determines that the conditions for forced oil return are met. When the conditions for forced oil return are met, the control module 500 controls the compressor 10 to adjust to the preset oil return frequency for operation and closes the control valve 80.

[0092] It can be understood that when the current operating frequency of the compressor 10 is relatively low (for example, lower than the first preset frequency Fr1), the oil return ability of the lubricating oil in the refrigerant circulation circuit is relatively weak, and the lubricating oil is more likely to accumulate in the pipes of the refrigerant circulation circuit. Therefore, forced oil return is required after the compressor 10 has been continuously operating for the first preset duration. When the current operating frequency of the compressor 10 is relatively high (for example, higher than the first preset frequency Fr1), the oil return ability of the lubricating oil in the refrigerant circulation circuit is relatively strong. Therefore, the compressor 10 can be forced to return oil after running for a relatively long time, that is, the second preset duration is greater than the first preset duration. Among them, the first preset duration and the second preset duration are set according to actual needs. Optionally, the second preset duration is n times the first preset duration, that is, T2 = nT1, where n > 1. Optionally, 6 ≤ n ≤ 8.

[0093] Please refer to Figure 8 , in one of the embodiments, in the step S5 described above, when the conditions for forced oil return are met, the step of controlling the compressor 10 to adjust to the preset oil return frequency for operation includes:

[0094] When the current operating frequency Fr of the compressor 10 is less than the preset oil return frequency Frh, the operating frequency of the compressor 10 is increased to the preset oil return frequency Frh;

[0095] When the current operating frequency Fr of the compressor 10 is greater than the preset oil return frequency Frh, the operating frequency of the compressor 10 is reduced to the preset oil return frequency Frh.

[0096] Specifically, the control module 500 of the control device of the air conditioning system includes an adjustment unit. When the compressor 10 meets the forced oil return condition, the adjustment unit adjusts the operating frequency of the compressor 10 according to the magnitude of the current operating frequency of the compressor 10, so that the compressor 10 can finally operate at the preset oil return frequency. For example, when the current operating frequency Fr of the compressor 10 is less than the preset oil return frequency Frh, the adjustment unit raises the operating frequency of the compressor 10 to the preset oil return frequency Frh. When the current operating frequency Fr of the compressor 10 is greater than the preset oil return frequency Frh, the adjustment unit reduces the operating frequency of the compressor 10 to the preset oil return frequency Frh. After the operating frequency of the compressor 10 is adjusted to the preset oil return frequency, a closing instruction is sent to the control valve 80 through the control unit of the control module 500, and the control valve 80 is closed to cut off the bypass pipeline 70.

[0097] When the compressor 10 operates at a high frequency, for example, the current operating frequency Fr of the compressor 10 is greater than the preset oil return frequency Frh, when the oil return condition is met, the compressor 10 needs to be reduced from the high current operating frequency to the preset oil return frequency. If the control valve 80 is immediately closed after the operating frequency of the compressor 10 is reduced, it will have a great impact on the air conditioning system and affect the operating reliability of the air conditioning system. In order to reduce the impact on the air conditioning system, in one embodiment, after the step of when the current operating frequency Fr of the compressor 10 is greater than the preset oil return frequency Frh, the operating frequency of the compressor 10 is reduced to the preset oil return frequency Frh, and before the step of closing the control valve 80, the following steps are further included:

[0098] Control the compressor 10 to operate at the preset oil return frequency for a third preset duration.

[0099] Specifically, when the current operating frequency Fr of the compressor 10 is greater than the preset oil return frequency Frh, the adjustment unit reduces the operating frequency of the compressor 10 to the preset oil return frequency Frh, and then the compressor 10 continues to operate at the preset oil return frequency for a period of time. During this process, the first timing module 600 can time the duration of the compressor 10 operating at the preset oil return frequency. When the duration of the compressor 10 operating at the preset oil return frequency reaches the third preset duration, it indicates that the entire system has reached a stable state. At this time, when the control valve 80 is closed, it will not have too much impact on the air conditioning system, so as to ensure the operating reliability of the air conditioning system. Among them, the third preset duration can be set according to the actual situation. For example, the third preset duration is T3, where 30s ≤ T3 ≤ 60s.

[0100] In order to be able to open the control valve 80 in a timely manner after the forced oil return is completed, so that the air conditioning system can resume its normal operating state, please refer to Figure 7 In one embodiment, after the step of closing the control valve 80, the following steps are further included:

[0101] S7. Obtain the cumulative closing duration of the control valve 80;

[0102] S8. When the cumulative closing duration of the control valve 80 reaches the fourth preset duration, open the control valve 80, and control the compressor 10 to operate at the operating frequency before the oil return operation.

[0103] Specifically, the control device of the air conditioning system includes a second timing module 700. After the control valve 80 is closed, the second timing module 700 measures the cumulative closing duration of the control valve 80; when the cumulative closing duration of the control valve 80 reaches the fourth preset duration, the second timing module 700 feeds back the result to the control module 500, and the control module 500 controls to open the control valve 80 to conduct the bypass pipeline 70. The control module 500 also controls the frequency of the compressor 10 to decrease or increase to resume the refrigeration or dehumidification operation at the operating frequency before the oil return operation. Among them, the fourth preset duration can be set according to the actual situation. For example, the fourth preset duration is T4, where 20s ≤ T3 ≤ 30s. Optionally, after opening the control valve 80 and controlling the compressor 10 to operate at the operating frequency before the oil return operation, it can return to step S3 to continue obtaining the operating state of the compressor 10, and then continuously monitor whether the compressor 10 needs forced oil return according to the subsequent steps.

[0104] Based on the above air conditioning system, the present invention also proposes a control device for an air conditioning system.

[0105] Please refer to Figure 2 In one embodiment of the present invention, the control device of the air conditioning system includes a mode detection module 100, a first judgment module 200, a state detection module 300, a second judgment module 400, and a control module 500: Among them, the mode detection module 100 is used to detect the operating mode of the air conditioning system; the first judgment module 200 is used to judge whether to perform an oil return operation detection according to the operating mode; the state detection module 300 is used to obtain the operating state of the compressor 10 when performing the oil return operation detection; the second judgment module 400 is used to judge whether the forced oil return condition is met according to the operating state of the compressor 10; the control module 500 is used to control the compressor 10 to adjust to the preset oil return frequency operation and control to close the control valve 80 when the forced oil return condition is met.

[0106] Specifically, when the air conditioning system is in a normal operating state, the control valve 80 is in an open state, at which time the bypass line 70 is connected, and the air conditioning system mainly plays a throttling role through the second throttling component 50. During the operation of the air conditioning system, the mode detection module 100 is used to detect the operating mode of the air conditioning system, wherein the operating mode of the air conditioning system includes a cooling mode, a dehumidification mode, and a heating mode. The mode detection module 100 feeds back the detection result to the first judgment module 200, and then the first judgment module 200 determines whether to perform the oil return operation detection according to the operating mode. When the operating mode is a cooling mode or a dehumidification mode, the first judgment module 200 determines that the oil return operation detection needs to be performed, and at this time, the oil return operation detection can be performed in the next step. When the operating mode is a non-cooling mode or a non-dehumidification mode (for example, the operating mode is a heating mode), the first judgment module 200 determines that the oil return operation detection does not need to be performed, and at this time the air conditioning system still operates normally in the current mode.

[0107] When the operation mode is the cooling mode or the dehumidification mode, the oil return operation detection is performed. During the oil return operation detection, the state detection module 300 is used to obtain the operation state of the compressor 10, such as the current operation frequency and the accumulated operation time of the compressor 10. Then the state detection module 300 feeds back the detection result to the second judgment module 400, and the second judgment module 400 judges whether the compressor 10 needs to meet the forced oil return condition according to the operation state of the compressor 10. If the forced oil return condition is met, it indicates that the compressor 10 needs to perform forced oil return. If the forced oil return condition is not met, it indicates that the compressor 10 does not need to perform forced oil return at present. The control module 500 receives the judgment result fed back by the second judgment module 400. When the forced oil return condition is met, the control module 500 controls the compressor 10 to adjust to the preset oil return frequency and control the closing of the control valve 80 so that the air conditioning system switches to the forced oil return state. In the forced oil return state, the compressor 10 uses its own suction characteristics to draw the oil in the indoor heat exchanger 60 and the outdoor heat exchanger 30 back to the compressor 10 to complete the forced oil return.

[0108] The control device of the above air conditioning system can determine whether the compressor 10 meets the forced oil return condition, and when the forced oil return condition is met, it can timely control the compressor 10 to adjust to the preset oil return operation frequency, and control the valve 80 to close to cut off the bypass pipeline 70, so that the air conditioning system switches to the forced oil return state. At this time, the first throttling component 40 and the second throttling component 50 are connected in series, and the entire refrigerant circulation loop is throttled by the combined action of the first throttling component 40 and the second throttling component 50. Through the combined action of the first throttling component 40 and the second throttling component 50, the pressure at the exhaust port of the compressor 10 is greater, so that a greater driving force can be provided for the flow of the lubricating oil and the refrigerant along the refrigerant circulation loop, and then the lubricating oil can flow back into the pump body 11 of the compressor 10 along with the refrigerant circulation loop. Thus, a better oil return effect can be achieved when the compressor 10 performs forced oil return, the compressor 10 can effectively complete oil return, the service life of the compressor 10 can be extended, and the operation reliability of the compressor 10 and the air conditioning system can be improved.

[0109] In order to more accurately determine the current operating state of the compressor 10, such as Figure 4 shown, in one embodiment, the state detection module 300 includes a first acquisition unit 310 and a second acquisition unit 320. Among them, the first acquisition unit 310 is used to acquire the current operating frequency Fr of the compressor 10; the second acquisition unit 320 is used to acquire the cumulative operating duration T of the compressor 10.

[0110] Specifically, when the current operating mode of the air conditioning system is the cooling mode or the dehumidification mode, the oil return operation detection is performed. The current operating frequency Fr of the compressor 10 is acquired through the first acquisition unit 310; the cumulative operating duration T of the compressor 10 is acquired through the second acquisition unit 320. Then, the first judgment unit judges whether the forced oil return condition is met according to the current operating frequency Fr and the cumulative operating duration T of the compressor 10. Since both the current operating frequency and the cumulative operating duration of the compressor 10 are considered, the actual operating state of the compressor 10 can be more accurately reflected, and reliable data can be provided for judging whether the compressor 10 meets the forced oil return condition.

[0111] Please refer to Figure 5, in one embodiment, the second determination module 400 includes a first determination unit 410 and a second determination unit 420. The first determination unit 410 is configured to determine that the forced oil return condition is satisfied when the current operating frequency Fr of the compressor 10 is less than a first preset frequency Fr1 and the cumulative operating duration T of the compressor 10 is greater than a first preset duration T1; the second determination unit 420 is configured to determine that the forced oil return condition is satisfied when the current operating frequency Fr of the compressor 10 is greater than the first preset frequency Fr1 and the cumulative operating duration T of the compressor 10 is greater than a second preset duration T2, where the second preset duration T2 is greater than the first preset duration T1.

[0112] Specifically, the first determination unit 410 presets through a built-in program that the condition for satisfying the forced oil return is that the current operating frequency Fr of the compressor 10 is less than the first preset frequency Fr1 and the cumulative operating duration T of the compressor 10 is greater than the first preset duration T1; the second determination unit 420 presets through a built-in program that the condition for satisfying the forced oil return is that the current operating frequency Fr of the compressor 10 is greater than the first preset frequency Fr1 and the cumulative operating duration T of the compressor 10 is greater than the second preset duration T2. After the state detection module 300 obtains the current operating frequency Fr and the cumulative operating duration T of the compressor 10, it feeds back the results to the second determination module 400. The first determination unit 410 and the second determination unit 420 of the second determination module 400 determine whether the forced oil return condition is satisfied according to different determination conditions. When the current operating frequency Fr of the compressor 10 is less than the first preset frequency Fr1 and the cumulative operating duration T of the compressor 10 is greater than the first preset duration T1, it is determined by the first determination unit 410 that the forced oil return condition is satisfied; when the current operating frequency Fr of the compressor 10 is greater than the first preset frequency Fr1 and the cumulative operating duration T of the compressor 10 is greater than the second preset duration T2, it is determined by the second determination unit 420 that the forced oil return condition is satisfied. When the forced oil return condition is satisfied, the control module 500 controls the compressor 10 to adjust to the preset oil return frequency for operation and closes the control valve 80.

[0113] In one embodiment, the control module 500 includes an adjustment unit. The adjustment unit is configured to increase the operating frequency of the compressor 10 to the preset oil return frequency Frh when the current operating frequency Fr of the compressor 10 is less than the preset oil return frequency Frh; the adjustment unit is further configured to decrease the operating frequency of the compressor 10 to the preset oil return frequency Frh when the current operating frequency Fr of the compressor 10 is greater than the preset oil return frequency Frh.

[0114] Specifically, when the compressor 10 meets the forced oil return condition, the adjustment unit adjusts the operating frequency of the compressor 10 according to the magnitude of the current operating frequency of the compressor 10, so that the compressor 10 can finally operate at a preset oil return frequency. For example, when the current operating frequency Fr of the compressor 10 is less than the preset oil return frequency Frh, the adjustment unit raises the operating frequency of the compressor 10 to the preset oil return frequency Frh. When the current operating frequency Fr of the compressor 10 is greater than the preset oil return frequency Frh, the adjustment unit lowers the operating frequency of the compressor 10 to the preset oil return frequency Frh. After the operating frequency of the compressor 10 is adjusted to the preset oil return frequency, a closing instruction is sent to the control valve 80 through the control unit of the control module 500, and the control valve 80 closes to cut off the bypass pipeline 70.

[0115] When the compressor 10 operates at a high frequency, for example, when the current operating frequency Fr of the compressor 10 is greater than the preset oil return frequency Frh, when the oil return condition is met, the compressor 10 needs to be reduced from the high current operating frequency to the preset oil return frequency. If the control valve 80 is immediately closed after the operating frequency of the compressor 10 is reduced, it will cause a large impact on the air conditioning system and affect the operating reliability of the air conditioning system. Please refer to Figure 3 In one embodiment, the control device of the air conditioning system further includes a first timing module 600, and the first timing module 600 is used to obtain the duration of the compressor 10 operating at the preset oil return frequency.

[0116] Specifically, when the current operating frequency Fr of the compressor 10 is greater than the preset oil return frequency Frh, the adjustment unit reduces the operating frequency of the compressor 10 to the preset oil return frequency Frh, and then the compressor 10 continues to operate at the preset oil return frequency for a period of time. During this process, the first timing module 600 can time the duration of the compressor 10 operating at the preset oil return frequency. When the duration of the compressor 10 operating at the preset oil return frequency reaches the third preset duration, it indicates that the entire system has reached a stable state. At this time, closing the control valve 80 will not cause too much impact on the air conditioning system, so as to ensure the operating reliability of the air conditioning system. Among them, the third preset duration can be set according to the actual situation. For example, the third preset duration is T3, where 30s ≤ T3 ≤ 60s.

[0117] In order to be able to open the control valve 80 in time after the forced oil return is completed, so that the air conditioning system can return to the normal operating state, in one embodiment, the control device of the air conditioning system further includes a second timing module 700, and the second timing module 700 is used to obtain the cumulative closing duration of the control valve 80. The control module 500 is further used to open the control valve 80 when the cumulative closing duration of the control valve 80 reaches the fourth preset duration, and control the compressor 10 to operate at the operating frequency before the oil return operation.

[0118] Specifically, after the control valve 80 is closed, the second timing module 700 measures the cumulative closing duration of the control valve 80. When the cumulative closing duration of the control valve 80 reaches the fourth preset duration, the second timing module 700 feeds back the result to the control module 500. The control module 500 controls the opening of the control valve 80 to conduct the bypass pipeline 70, and the control module 500 also controls the frequency of the compressor 10 to decrease or increase to resume the operating frequency before the oil return operation and continue the refrigeration or dehumidification operation.

[0119] The present invention also provides a computer-readable storage medium, on which a control program of the air conditioner system is stored. When the control program of the air conditioner system is executed by a processor, it performs the steps of the oil return control method of the air conditioner system as described above. Among them, the specific implementation manner of the control method of the air conditioner system can refer to the above embodiments. Since this computer-readable storage medium adopts all the technical solutions of the above embodiments, it has all the beneficial effects brought by the above embodiments and will not be elaborated here.

[0120] The above are only the preferred embodiments of the present invention, and do not limit the patent scope of the present invention accordingly. Any equivalent structural transformation made by using the content of the specification and drawings of the present invention under the inventive concept of the present invention, or direct / indirect application in other related technical fields, is included in the patent protection scope of the present invention.

Claims

1. An oil return control method for an air conditioning system, which is used for an air conditioning system, characterized in that, The air conditioning system includes a compressor, a four-way valve, an outdoor heat exchanger, a first throttling component, a second throttling component, and an indoor heat exchanger that are interconnected to form a refrigerant circulation loop. The refrigerant circulation loop further includes a bypass pipeline that is parallel to the first throttling component. The bypass pipeline is provided with a control valve. The air conditioning system has a normal operation state and a forced oil return state. In the normal operation state, the control valve is opened to conduct the bypass pipeline. In the forced oil return state, the control valve is closed to cut off the bypass pipeline; The oil return control method of the air conditioning system includes the following steps: Detect the current operation mode of the air conditioning system; Judge whether to perform an oil return operation detection according to the operation mode; When the operation mode is the refrigeration mode or the dehumidification mode, perform an oil return operation detection; When the operation mode is a non-refrigeration mode or a non-dehumidification mode, do not perform an oil return operation detection; Obtain the operation state of the compressor when performing an oil return operation detection; Judge whether the forced oil return condition is satisfied according to the operation state of the compressor; When the forced oil return condition is satisfied, control the compressor to adjust to run at a preset oil return frequency; Close the control valve.

2. The oil return control method of the air conditioning system according to claim 1, wherein The step of performing an oil return operation detection to obtain the operation state of the compressor includes: Obtain the current operation frequency Fr and the cumulative operation duration T of the compressor.

3. The oil return control method for an air conditioning system according to claim 2, characterized in that, The step of judging whether the forced oil return condition is satisfied according to the operation state of the compressor includes: When the current operation frequency Fr of the compressor is less than the first preset frequency Fr1 and the cumulative operation duration T of the compressor is greater than the first preset duration T1, it is determined that the forced oil return condition is satisfied; When the current operation frequency Fr of the compressor is greater than the first preset frequency Fr1 and the cumulative operation duration T of the compressor is greater than the second preset duration T2, it is determined that the forced oil return condition is satisfied, where the second preset duration T2 is greater than the first preset duration T1.

4. The oil return control method of the air conditioning system according to claim 1, characterized in that, The step of controlling the compressor to adjust to run at a preset oil return frequency when the forced oil return condition is satisfied includes: When the current operation frequency Fr of the compressor is less than the preset oil return frequency Frh, raise the operation frequency of the compressor to the preset oil return frequency Frh; When the current operation frequency Fr of the compressor is greater than the preset oil return frequency Frh, lower the operation frequency of the compressor to the preset oil return frequency Frh.

5. The oil return control method of the air conditioning system according to claim 4, characterized in that, After the step of when the current operation frequency Fr of the compressor is greater than the preset oil return frequency Frh, lower the operation frequency of the compressor to the preset oil return frequency Frh, and before the step of closing the control valve, the following steps are further included: Control the compressor to run at a preset oil return frequency for a third preset duration.

6. The oil return control method of the air conditioning system according to any one of claims 1 to 5, characterized in that, After the step of closing the control valve, the following steps are further included: Obtain the cumulative closing duration of the control valve; When the cumulative closing duration of the control valve reaches the fourth preset duration, open the control valve and control the compressor to resume running at the operation frequency before the oil return operation.

7. A control device for an air conditioning system, which is used for the air conditioning system, characterized in that, The air conditioning system includes a compressor, a four-way valve, an outdoor heat exchanger, a first throttling component, a second throttling component, and an indoor heat exchanger that are interconnected to form a refrigerant circulation loop. The refrigerant circulation loop further includes a bypass pipeline that is parallel to the first throttling component. The bypass pipeline is provided with a control valve. The air conditioning system has a normal operation state and a forced oil return state. In the normal operation state, the control valve is opened to conduct the bypass pipeline. In the forced oil return state, the control valve is closed to cut off the bypass pipeline; The control device of the air conditioning system includes: A mode detection module for detecting the operation mode of the air conditioning system; A first judgment module for judging whether to perform an oil return operation detection according to the operation mode; A state detection module for obtaining the operation state of the compressor when performing the oil return operation detection; A second judgment module for judging whether the forced oil return condition is satisfied according to the operation state of the compressor; A control module for controlling the compressor to adjust to run at a preset oil return frequency and controlling the closing of the control valve when the forced oil return condition is satisfied.

8. The control device of the air conditioning system according to claim 7, characterized in that, The state detection module includes: A first acquisition unit for acquiring the current operation frequency Fr of the compressor; A second acquisition unit for acquiring the cumulative operation duration T of the compressor.

9. The control device of the air conditioning system according to claim 8, characterized in that, The second judgment module includes: A first determination unit for determining that the forced oil return condition is satisfied when the current operation frequency Fr of the compressor is less than a first preset frequency Fr1 and the cumulative operation duration T of the compressor is greater than a first preset duration T1; A second determination unit for determining that the forced oil return condition is satisfied when the current operation frequency Fr of the compressor is greater than the first preset frequency Fr1 and the cumulative operation duration T of the compressor is greater than a second preset duration T2, where the second preset duration T2 is greater than the first preset duration T1.

10. The control device of the air conditioning system according to claim 7, characterized in that, The control module includes an adjustment unit. The adjustment unit is used to increase the operation frequency of the compressor to the preset oil return frequency Frh when the current operation frequency Fr of the compressor is less than the preset oil return frequency Frh; the adjustment unit is further used to decrease the operation frequency of the compressor to the preset oil return frequency Frh when the current operation frequency Fr of the compressor is greater than the preset oil return frequency Frh.

11. The control device of the air conditioning system according to claim 7, characterized in that, It further includes a first timing module for acquiring the duration of the compressor running at the preset oil return frequency.

12. The control device of the air conditioning system according to any one of claims 7 to 11, characterized in that, It further includes a second timing module for acquiring the cumulative closing duration of the control valve. The control module is further used to open the control valve and control the compressor to resume running at the operation frequency before the oil return operation when the cumulative closing duration of the control valve reaches a fourth preset duration.

13. A computer-readable storage medium, characterized in that, A control program of the air conditioning system is stored on the computer-readable storage medium. The control program of the air conditioning system is executed by a processor to perform the steps of the oil return control method of the air conditioning system according to any one of claims 1 to 6.

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