Air conditioner

Abstract

The application relates to an air conditioner, belonging to the technical field of air conditioners, which comprises a compressor, an outdoor heat exchanger, an indoor heat exchanger, a refrigerant pipeline, a low-pressure pipeline, a regenerator, an expansion valve and a controller. One end of the outdoor heat exchanger is communicated with the compressor. The refrigerant pipeline is used for the communication between the outdoor heat exchanger and the indoor heat exchanger. The low-pressure pipeline is used for the communication between the indoor heat exchanger and the compressor. The regenerator is arranged on the refrigerant pipeline and the low-pressure pipeline and is used for heat exchange between the refrigerant pipeline and the low-pressure pipeline. The expansion valve is arranged on the refrigerant pipeline and is located on the side of the regenerator close to the indoor heat exchanger. The controller is configured to control the expansion valve to increase the opening degree of the expansion valve after entering an oil return circulation mode.

Description

Technical Field

[0001] This application relates to the technical field of air conditioners, and more particularly to an air conditioner. Background Technology

[0002] A multi-split air conditioning system typically consists of one or more outdoor units and multiple indoor units. An outdoor unit includes at least a compressor, an outdoor heat exchanger, and an outdoor expansion valve, while an indoor unit generally includes an indoor heat exchanger and an indoor expansion valve. Due to the large number of units connected and the large capacity of the outdoor units, the connecting pipes within the same system are often very long, sometimes exceeding 1000 meters.

[0003] During the operation of an air conditioning unit, the compressor discharges a small amount of lubricating oil into the system along with the high-temperature, high-pressure refrigerant. If the compressor frequency is low and the refrigerant flow rate is slow at this time, the refrigerant discharged into the system is difficult to carry back to the compressor via the refrigerant flow and instead remains in the system. This results in the migration of refrigerant oil from the compressor to the system. If low-frequency operation is maintained for a long time, it will lead to insufficient oil in the compressor, causing wear and even coil burnout. Summary of the Invention

[0004] This invention at least partially solves one of the technical problems in the related art.

[0005] Therefore, this application aims to provide an air conditioner in which the refrigerant in the section of the refrigerant pipeline between the outdoor heat exchanger and the expansion valve is a high-temperature, high-pressure gaseous refrigerant output from the compressor. The refrigerant in the low-pressure pipeline is a low-temperature liquid refrigerant. When passing through the regenerator, the refrigerant in the refrigerant pipeline is cooled by the refrigerant in the low-pressure pipeline, causing the refrigerant in the refrigerant pipeline to become a two-phase refrigerant mixture. The formation of the two-phase refrigerant enhances the refrigerant's flushing ability, thereby effectively promoting the return of lubricating oil from the system to the compressor, avoiding compressor oil shortage problems caused by low-frequency operation.

[0006] To achieve the above objectives, the present invention provides an air conditioner, comprising:

[0007] compressor;

[0008] An outdoor heat exchanger, one end of which is connected to the compressor;

[0009] Indoor heat exchanger;

[0010] Refrigerant piping, which is used for the connection between the outdoor heat exchanger and the indoor heat exchanger;

[0011] A low-pressure pipeline is used to connect the indoor heat exchanger to the compressor;

[0012] A regenerator is provided between the refrigerant pipeline and the low-pressure pipeline for heat exchange between the refrigerant pipeline and the low-pressure pipeline;

[0013] An expansion valve is provided in the refrigerant line and located on the side of the regenerator closer to the indoor heat exchanger.

[0014] The controller is configured to control the expansion valve to increase the opening degree of the expansion valve after entering the return oil circulation mode.

[0015] In this technical solution, the refrigerant in the section of the refrigerant pipeline between the outdoor heat exchanger and the expansion valve is the high-temperature, high-pressure gaseous refrigerant output from the compressor. The refrigerant in the low-pressure pipeline is a low-temperature liquid refrigerant. When passing through the regenerator, the refrigerant in the main refrigerant pipeline is cooled by the refrigerant in the low-pressure pipeline, causing it to become a two-phase refrigerant mixture. This two-phase refrigerant formation enhances the refrigerant's flushing ability, effectively promoting the return of lubricating oil from the system to the compressor and preventing compressor oil shortage problems caused by low-frequency operation.

[0016] In some embodiments of this application, the controller is configured as follows:

[0017] After entering the judgment mode:

[0018] The frequency of the compressor is obtained. If the frequency of the compressor is lower than the preset frequency value and the running time reaches the first preset time, the oil return circulation mode is entered.

[0019] In the technical solution, when the compressor frequency is lower than a preset value and the running time reaches a first preset time, there may be a situation where lubricating oil is present in the pipeline, resulting in insufficient lubricating oil in the compressor. This frequency and time-based detection logic can accurately determine whether the compressor is in a low-frequency operating state, thereby promptly initiating the oil return circulation mode to prevent lubricating oil from accumulating in the system and ensuring normal lubrication of the compressor.

[0020] In some embodiments of this application, an oil level sensor is provided inside the compressor;

[0021] The controller is configured to: after entering the judgment mode, control the oil level sensor to detect the current oil level, and if the current oil level is lower than the preset oil level, enter the oil return circulation mode.

[0022] In this technical solution, an oil level sensor is installed inside the compressor to directly detect the oil level. When the oil level is lower than a preset value, it is determined that the lubricating oil content inside the compressor is low, requiring the compressor to enter the oil return circulation mode. This design can directly monitor the oil level status inside the compressor, and its judgment is accurate, enabling timely entry into the oil return circulation mode to avoid compressor wear or burnout caused by excessively low oil levels. It also improves the system's response speed and reliability.

[0023] In some embodiments of this application, an indoor temperature sensor is also provided, which is used to detect the indoor return air temperature value;

[0024] The controller is configured to calculate the difference between the indoor return air temperature and the currently set temperature. If the difference is greater than a threshold, a preset frequency increment is added to the current compressor frequency to obtain the operating frequency value, and the compressor is controlled to operate at the operating frequency value.

[0025] In this technical solution, changes in the refrigerant state of the indoor unit lead to variations in its capacity. Therefore, the compressor frequency is adjusted according to the indoor heat load to ensure that the current operating temperature reaches the required set temperature. Furthermore, this design ensures the normal operation of the oil return circulation mode while dynamically adjusting the compressor frequency based on indoor temperature requirements, preventing lubricant migration issues caused by excessively low frequencies, and simultaneously improving system comfort and energy efficiency.

[0026] In some embodiments of this application, the following are also included:

[0027] A first detector is used to detect the suction superheat of the compressor;

[0028] The controller is configured to: after entering the oil return circulation mode; control the first detector to detect the suction superheat of the compressor and obtain the suction superheat value; determine whether the suction superheat value is lower than the preset suction superheat value, and if so, determine the duration;

[0029] During the duration determination, it is determined whether the duration for which the inhalation superheat value is lower than the preset inhalation superheat value is greater than the second preset time. If not, the current state is maintained; if so, the determination mode is re-entered.

[0030] In the technical solution, excessively high suction superheat indicates poor heat exchange, possibly due to the presence of lubricating oil in the refrigerant. Therefore, the oil return circulation mode is maintained. When the suction superheat decreases below the preset value and remains below it for a certain period, it indicates normal heat exchange, and the lubricating oil in the pipes may have been flushed out. However, for safety, the system re-enters the judgment mode for a second assessment. Only when it is confirmed that there is no lubricating oil in the pipes, or that a small amount of lubricating oil has no significant impact on the air conditioner, is the oil return circulation mode completely exited. The judgment process is logically rigorous, minimizing the possibility of misjudgment.

[0031] In some embodiments of this application, the following are also included:

[0032] The second detector is used to detect the exhaust superheat of the compressor;

[0033] The controller is configured to: after entering the oil return circulation mode; control the second detector to detect the exhaust superheat of the compressor and obtain the exhaust superheat value; determine whether the exhaust superheat value is lower than the preset exhaust superheat value, and if so, determine the duration;

[0034] During the duration determination, it is determined whether the duration for which the exhaust superheat value is lower than the preset exhaust superheat value is greater than the third preset time. If not, the current state is maintained; if so, the determination mode is re-entered.

[0035] In the technical solution, excessively high exhaust superheat indicates poor heat exchange performance, possibly due to the presence of lubricating oil in the refrigerant. Therefore, the oil return circulation mode is maintained. When the exhaust superheat drops below the preset value and remains below it for a certain period, it indicates normal heat exchange performance, and the lubricating oil in the pipes may have been flushed out. However, for safety, the system re-enters the judgment mode for further assessment. Only when it is confirmed that there is no lubricating oil in the pipes, or that a small amount of lubricating oil has no significant impact on the air conditioner, is the oil return circulation mode completely exited. The judgment process is logically rigorous, minimizing the possibility of misjudgment.

[0036] In some embodiments of this application, the following are also included:

[0037] The four-way valve includes a first port, a second port, a third port, and a fourth port; the first port is connected to the output end of the compressor, the second port is connected to the input end of the compressor, the third port is connected to the outdoor heat exchanger, and the fourth port is connected to the end of the regenerator in the low-pressure pipeline away from the indoor heat exchanger.

[0038] In the technical solution, in cooling mode, the refrigerant enters the outdoor heat exchanger through the first and third interfaces, passes through the indoor heat exchanger, and then flows back to the compressor through the fourth and second interfaces. In heating mode, the refrigerant enters the indoor heat exchanger through the first and fourth interfaces, passes through the outdoor heat exchanger, and then flows back to the compressor through the third and first interfaces. In both heating and cooling modes, the refrigerant passes through the regenerator, achieving the effect of flushing the pipes.

[0039] In addition, this application also provides an air conditioner, which includes:

[0040] compressor;

[0041] An outdoor heat exchanger, one end of which is connected to the compressor;

[0042] Indoor heat exchanger;

[0043] Refrigerant piping, which is used for the connection between the outdoor heat exchanger and the indoor heat exchanger;

[0044] A heat recovery passage, which is connected in parallel with the refrigerant pipeline;

[0045] A connecting pipe, wherein the connecting pipe is used to connect the indoor heat exchanger to the compressor;

[0046] A regenerator is disposed between the regenerating passage and the connecting pipe, and is used for heat exchange between the regenerating passage and the connecting pipe;

[0047] A valve module, which is used to open or close the regeneration passage to allow refrigerant to pass through the refrigerant pipeline or through the regeneration passage;

[0048] The controller is configured to, upon entering the oil return circulation mode, control the valve module to open the regenerative passage so that the refrigerant passes through the regenerative passage.

[0049] In the technical solution, a valve module allows users to select whether the refrigerant flows through the regenerator, enabling them to choose whether to activate the oil return circulation mode. This meets user needs in different scenarios, enhances the flexibility and applicability of the air conditioner, and provides users with a more personalized and efficient user experience.

[0050] In some embodiments of this application, the section of the refrigerant pipeline located between the two ends of the heat recovery passage is a high-pressure section;

[0051] The valve module is used to open the high-pressure section and close the regenerative passage, or close the high-pressure section and open the regenerative passage.

[0052] In this technical solution, when not in oil return circulation mode, the high-pressure section is opened and the regenerative passage is closed. The refrigerant flows directly through the pipeline. When entering oil return circulation mode, the regenerative passage is opened, and all or part of the refrigerant flows through the regenerative passage and exchanges heat with the connecting pipeline in the regenerator, thus turning the refrigerant that has passed through the regenerative passage into a two-phase refrigerant. This structural design eliminates unnecessary piping, saving costs.

[0053] In some embodiments of this application, it further includes:

[0054] An expansion valve is disposed in the regenerative passage and located on the side of the regenerator closer to the indoor heat exchanger;

[0055] The controller is configured to control the expansion valve to increase the opening degree of the expansion valve after entering the return oil circulation mode.

[0056] In this technical solution, the opening of the expansion valve is increased when entering the oil return circulation mode to control the superheat of the intake and exhaust gases to the target value, thereby controlling the refrigerant state in the overheated online gas pipes to a two-phase state. Furthermore, this design reduces refrigerant flow resistance and accelerates refrigerant flow rate. This design helps enhance the refrigerant's flushing ability, further promotes lubricating oil return, and optimizes the system's cooling or heating performance.

[0057] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0058] Figure 1 This is a schematic diagram of the overall structure of an air conditioner according to an embodiment of this application;

[0059] Figure 2 This is a schematic diagram of the overall structure of an air conditioner according to an embodiment of this application;

[0060] Figure 3 This is a schematic diagram of the refrigerant flow direction in the normal cooling mode of an air conditioner according to the embodiments of this application;

[0061] Figure 4 This is a schematic diagram of the refrigerant flow direction in the refrigeration mode under the oil return circulation mode according to the embodiments of this application;

[0062] Figure 5 This is a schematic diagram of the refrigerant flow direction in the heating mode of an air conditioner according to an embodiment of this application;

[0063] Figure 6 This is a schematic diagram of the refrigerant flow direction in the heating mode under the oil return circulation mode according to the embodiments of this application;

[0064] Figure 7This is a schematic diagram of the structure of an air conditioner according to an embodiment of this application;

[0065] Figure 8 This is a flowchart illustrating the operation of an air conditioner according to an embodiment of this application;

[0066] Figure 9 This is a flowchart illustrating the operation of an air conditioner according to an embodiment of this application;

[0067] Figure 10 This is a flowchart illustrating the operation of an air conditioner according to an embodiment of this application;

[0068] Figure 11 This is a flowchart illustrating the operation of an air conditioner according to an embodiment of this application;

[0069] Figure 12 This is a schematic diagram of the structure of an air conditioner according to an embodiment of this application;

[0070] Figure 13 This is a flowchart illustrating the operation of an air conditioner according to an embodiment of this application;

[0071] Figure 14 This is a schematic diagram of the structure of an air conditioner according to an embodiment of this application;

[0072] Figure 15 This is a flowchart illustrating the operation of an air conditioner according to an embodiment of this application;

[0073] Figure 16 This is a schematic diagram of the structure of an air conditioner according to an embodiment of this application;

[0074] Figure 17 This is a flowchart of the operation of an air conditioner according to an embodiment of this application.

[0075] In the above diagrams: 100, compressor; 200, first pipeline; 300, second pipeline; 400, regenerator; 500, first valve; 600, second valve; 700, third valve; 800, fourth valve; 900, four-way valve; 110, outdoor heat exchanger; 120, outdoor fan; 130, outdoor unit throttle valve; 140, indoor unit throttle valve; 150, indoor heat exchanger; 160, indoor fan; 170, first three-way valve; 180, second three-way valve; 190, refrigerant pipeline; 210, regeneration passage; 220, connecting pipeline; 230, valve module. Detailed Implementation

[0076] In the description of this invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0077] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0078] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0079] In this invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0080] The present invention will now be described in detail through exemplary embodiments. However, it should be understood that, without further description, elements, structures, and features in one embodiment may be advantageously incorporated into other embodiments.

[0081] In this application, the air conditioner includes a compressor, an outdoor heat exchanger, and an indoor heat exchanger. The compressor supplies refrigerant to either the indoor or outdoor heat exchanger. In heating mode, the refrigerant is cooled by the outdoor heat exchanger, then enters the indoor heat exchanger to cool the room before returning to the compressor. In cooling mode, the refrigerant is heated by the indoor heat exchanger, then enters the outdoor heat exchanger before returning to the compressor.

[0082] In existing technology, to prevent compressor wear and even coil burnout caused by prolonged low-frequency operation in multi-split air conditioners, oil return control is implemented when the low-frequency operation time exceeds a set time or when a low compressor oil level is detected. Oil return control generally takes two forms: 1. Directly increasing the compressor operating frequency, using high-speed refrigerant flow to carry the lubricating oil back to the compressor; 2. If the unit was in heating mode before implementing oil return control, in addition to increasing the compressor operating frequency, a four-way valve can be used to reverse the flow of refrigerant and refrigerant oil in the piping and indoor units, and the indoor unit fan can be shut off to return a large amount of refrigerant oil.

[0083] Both solutions have certain problems: 1. Increasing the compressor frequency and returning oil can cause a mismatch between load and output capacity, and there is a risk of the indoor unit's heat exchanger freezing due to a sudden drop in evaporation temperature during the refrigeration cycle; 2. If the oil return is reversed through a four-way valve during heating operation, the indoor unit's heating capacity will suddenly decrease, reducing thermal comfort; 3. Frequent switching of operating modes or start-stop may cause drastic changes in compressor load, shortening the compressor's lifespan; 4. Reduced energy efficiency, whether through increasing the frequency or switching the four-way valve for oil return, the compressor needs to do a lot more work to carry the refrigerant oil back to the compressor; 5. Increased vibration and noise, increasing the compressor frequency will cause pipe vibration, and switching the four-way valve will cause drastic changes in system pressure, both of which may cause pipe resonance and increased refrigerant flow noise, affecting user experience.

[0084] In the following, embodiments of this application will be described in detail with reference to the accompanying drawings.

[0085] Please refer to Figures 1 to 11 In one illustrative embodiment of the air conditioner of the present invention, in a first aspect, the air conditioner includes a compressor 100, the output end of the compressor 100 is connected to a high-pressure pipeline, and the input end of the compressor 100 is connected to a low-pressure pipeline.

[0086] In some embodiments, the air conditioner further includes a four-way valve 900, an outdoor heat exchanger 110, and an indoor heat exchanger 150. The four-way valve 900 has a first port, a second port, a third port, and a fourth port; the first port is connected to a high-pressure pipeline; the second port is connected to a low-pressure pipeline. The outdoor heat exchanger 110 is connected to the third port. The indoor heat exchanger 150 is connected to the fourth port; the indoor heat exchanger 150 is in communication with the outdoor heat exchanger 110. By switching the four-way valve 900, the flow direction of the refrigerant is changed, thereby altering whether the refrigerant enters the outdoor heat exchanger 110 or the indoor heat exchanger 150 first, thus switching between cooling and heating modes.

[0087] In some embodiments, the indoor heat exchanger 150 and the outdoor heat exchanger 110 are connected by a refrigerant line 190. Refrigerant flows between the indoor heat exchanger 150 and the outdoor heat exchanger 110 through the refrigerant line 190.

[0088] In some embodiments, an outdoor fan 120 is also provided on one side of the outdoor heat exchanger 110. The outdoor fan 120 is used to blow air toward the outdoor heat exchanger 110 so that the air exchanges heat with the outdoor heat exchanger 110 and changes the temperature of the refrigerant.

[0089] In some embodiments, an indoor fan 160 is also provided on one side of the indoor heat exchanger 150. The indoor fan 160 is used to blow air toward the indoor heat exchanger 150 so that the air exchanges heat with the indoor heat exchanger 150 and changes the indoor temperature.

[0090] In some embodiments, the air conditioner also includes an outdoor unit throttling valve 130, which is disposed on the refrigerant line 190. Specifically, the outdoor unit throttling valve 130 is located near the outdoor heat exchanger 110. The outdoor unit throttling valve 130 is mainly responsible for the overall refrigerant distribution and pressure balance of the system.

[0091] In some embodiments, the air conditioner further includes an indoor unit throttling valve 140, which is disposed on the refrigerant line 190. Specifically, the indoor unit throttling valve 140 is located near the indoor heat exchanger 150. The indoor unit throttling valve 140 is used for precise control of the corresponding individual indoor unit evaporator and for indoor temperature regulation.

[0092] In some embodiments, the air conditioner is a multi-split air conditioner, which has multiple indoor units and corresponding multiple indoor heat exchangers 150, and each indoor heat exchanger 150 is connected in parallel to the outdoor heat exchanger 110 through a refrigerant pipeline 190.

[0093] In some embodiments, when there are multiple indoor heat exchangers 150, a control valve is provided on the refrigerant pipeline 190 corresponding to each indoor heat exchanger 150. When the user selects to turn on different indoor units as needed, the corresponding control valve is opened, and the refrigerant can enter the corresponding indoor heat exchanger 150 through the control valve, thereby realizing the turning on or off of the corresponding indoor unit.

[0094] In some embodiments, when there are multiple indoor heat exchangers 150, each indoor heat exchanger 150 is provided with a corresponding indoor unit throttling valve 140 on its refrigerant pipeline 190. The indoor unit throttling valve 140 regulates the refrigerant flow into the corresponding indoor heat exchanger 150, thereby achieving the regulation of the temperature of the individual indoor unit.

[0095] In some embodiments, the air conditioner further includes a first pipe 200, a second pipe 300, and a regenerator 400. The first pipe 200 is connected in parallel to the high-pressure pipe. The second pipe 300 is connected in parallel to the low-pressure pipe. The regenerator 400 is disposed between the first pipe 200 and the second pipe 300, and is used for heat exchange between the first pipe 200 and the second pipe 300. The refrigerant in the low-pressure pipe is a low-pressure, low-temperature liquid refrigerant, and the refrigerant in the high-pressure pipe is a high-pressure, high-temperature gaseous refrigerant; therefore, the first pipe 200, which is connected in parallel with the first high-pressure pipe, also contains a high-pressure, high-temperature gaseous refrigerant, and the second pipe 300, which is connected in parallel with the low-pressure pipe, also contains a low-pressure, low-temperature liquid refrigerant. Therefore, after the first pipe 200 and the second pipe 300 exchange heat through the heat exchanger, the temperature of the liquid refrigerant in the first pipe 200 is reduced. Based on the characteristics of the refrigerant, some of the refrigerant in the first pipe 200 cools down and becomes liquid again. At this point, the first pipe 200 contains a two-phase refrigerant consisting of liquid and gas. Compared to gaseous refrigerant, the two-phase refrigerant has a better flushing effect on the pipes. It can flush away the residual lubricating oil in the outdoor heat exchanger 110, the indoor heat exchanger 150, and the refrigerant pipe 190, allowing the lubricating oil to flow back to the compressor 100, thus preventing the compressor 100 from running out of oil.

[0096] In some embodiments, the air conditioner further includes a first valve 500, a second valve 600, a third valve 700, and a fourth valve 800. The first valve 500 is used to open and close the high-pressure pipeline. The second valve 600 is used to open and close the low-pressure pipeline. The third valve 700 is used to open and close the first pipeline 200. The fourth valve 800 is used to open and close the second pipeline 300. When two-phase refrigerant flushing of the pipeline is not required, the first valve 500 and the second valve 600 are open, and the third valve 700 and the fourth valve 800 are closed, at which point the air conditioner is in normal operation. When the compressor 100 is short of oil, the first valve 500 and the second valve 600 are closed, and the third valve 700 and the fourth valve 800 are opened, so that the high-temperature gaseous refrigerant in the first pipeline 200 exchanges heat with the low-temperature refrigerant in the second pipeline 300, becoming a two-phase refrigerant. The two-phase refrigerant then flushes the pipeline through the four-way valve 900. It can control the first valve 500, the second valve 600, the third valve 700 and the fourth valve 800 as needed to flush the pipes inside the air conditioner.

[0097] In some embodiments, the air conditioner further includes a controller configured to close the first valve 500 and the second valve 600, and open the third valve 700 and the fourth valve 800 after entering the oil return circulation mode. The controller controls the first valve 500, the second valve 600, the third valve 700, and the fourth valve 800, and can also automatically select whether to enter the oil return circulation mode based on different conditions.

[0098] Through the above scheme, a regenerator 400 is installed between the high-pressure and low-pressure pipelines, connected in parallel to the first pipeline 200 and the second pipeline 300. Simultaneously, by controlling the opening and closing of the first valve 500, the second valve 600, the third valve 700, and the fourth valve 800, heat exchange between the high-pressure and low-pressure refrigerants can be achieved using the regenerator 400 when entering the oil return circulation mode. This design allows the high-temperature, high-pressure refrigerant discharged from the compressor 100 to exchange heat with the low-temperature, low-pressure refrigerant, condensing into a high-temperature, high-pressure two-phase refrigerant. The formation of the two-phase refrigerant enhances the refrigerant's flushing ability, thereby effectively promoting the return of lubricating oil from the system to the compressor 100, avoiding the oil shortage problem in the compressor 100 caused by low-frequency operation.

[0099] In some embodiments, the controller is configured to enter a judgment mode upon receiving a control signal. Specifically, this can be achieved by receiving remote control signals, Bluetooth signals, or network signals. That is, the user can enter the judgment mode using a remote control, mobile phone, cloud-based delivery, Wi-Fi (wireless communication technology), etc. The judgment mode is used to detect whether the air conditioner's compressor 100 is short of oil. If it is, it can directly enter the oil return circulation mode to improve the oil shortage situation of the compressor 100.

[0100] In some embodiments, the control signal may also be a power-on signal or a compressor 100 start signal; that is, the air conditioner enters the judgment mode after being turned on. Because the compressor 100 starts after the air conditioner is turned on, when the compressor 100 outputs refrigerant, it usually carries a large amount of lubricating oil into the pipeline (in this article, the refrigerant pipeline, high-pressure pipeline, low-pressure pipeline, etc., used for refrigerant flow are all referred to as pipelines). Therefore, the judgment mode is activated when the air conditioner is turned on, which can quickly enter the oil return circulation mode according to the situation, thereby improving the protection effect of the air conditioner.

[0101] Furthermore, the power-on signal specifically refers to the power-on signal of any one indoor unit.

[0102] In some embodiments, the controller is configured to directly enter the oil return circulation mode upon receiving a control signal. Because the compressor 100 starts when the air conditioner is turned on, and the compressor 100 typically carries a large amount of lubricating oil into the pipeline when outputting refrigerant, directly entering the oil return circulation mode can directly flush the lubricating oil in the pipeline, allowing the lubricating oil to flow back to the compressor 100. This method ensures that the compressor 100 does not experience oil shortage each time the air conditioner is turned on.

[0103] In some embodiments, the controller is configured to, upon entering a judgment mode, acquire the current frequency value of the compressor 100. If the current frequency value of the compressor 100 is lower than a preset frequency value and the running time reaches a first preset time, then it enters the oil return circulation mode. When the frequency of the compressor 100 is lower than the preset value and the running time reaches the first preset time, there may be a situation where the lubricating oil is in the pipeline and the compressor 100 has insufficient lubricating oil. This frequency and time-based detection logic can accurately determine whether the compressor 100 is in a low-frequency operating state, thereby promptly initiating the oil return circulation mode to prevent lubricating oil from accumulating in the system and ensuring normal lubrication of the compressor 100.

[0104] Furthermore, a control unit is installed inside the compressor 100. After entering the judgment mode, the specific steps for obtaining the compressor 100 frequency are as follows: the controller directly obtains the current frequency value of the compressor 100 from the control unit. This method provides a more intuitive and accurate result.

[0105] In some embodiments, the air conditioner further includes a compressor detection unit, which is used to detect the current frequency of the compressor 100. After entering the judgment mode, the specific steps for obtaining the compressor 100 frequency are as follows: controlling the compressor detection unit to detect the current frequency of the compressor 100 and obtain the current frequency value; and the control unit obtaining the current frequency value.

[0106] Specifically, the controller is configured to: upon entering the judgment mode, acquire the current frequency value of compressor 100, determine whether the current frequency value of compressor 100 is lower than a preset frequency value; if not, enter the exit judgment mode. If yes, acquire the continuous running time of compressor 100 at a frequency lower than the preset value, determine whether the running time exceeds a first preset time; if not, enter the exit judgment mode. If yes, enter the oil return circulation mode.

[0107] It is worth noting that while obtaining the current frequency value of compressor 100, the continuous running time of compressor 100 at a frequency lower than the preset value can also be obtained directly.

[0108] Specifically, when the controller obtains the current frequency value through the control unit in the compressor 100, the controller obtains the aforementioned operating time through the control unit in the compressor 100.

[0109] When the controller obtains the current frequency value through the compressor detection unit, the compressor detection unit records the operating time of compressor 100 when the current frequency value is lower than the preset frequency value. The controller obtains the above operating time through the compressor detection unit.

[0110] In another embodiment, the controller is configured to start calculating the duration of operation when the current frequency value of the compressor 100 is lower than the preset frequency value, so that it can be obtained immediately after the judgment mode is activated.

[0111] In some embodiments, an oil level sensor is installed inside the compressor 100. The controller is configured to: upon entering a judgment mode, control the oil level sensor to detect the current oil level; if the current oil level is lower than a preset oil level, enter the oil return circulation mode. By installing an oil level sensor inside the compressor 100, the oil level inside the compressor 100 is directly detected. When the oil level is lower than the preset value, it is determined that the lubricating oil content inside the compressor 100 is low, and the oil return circulation mode needs to be entered. This design can directly monitor the oil level status inside the compressor 100, and its judgment is accurate, enabling timely entry into the oil return circulation mode, avoiding wear or burnout of the compressor 100 due to excessively low oil levels, while improving the system's response speed and reliability.

[0112] Furthermore, the controller is configured to: upon entering the judgment mode, control the oil level sensor to detect the current oil level and acquire the current oil level value detected by the sensor. It then determines whether the current oil level is lower than a preset oil level; if not, it exits the judgment mode. If so, it enters the return oil circulation mode.

[0113] It is worth noting that, in the above two judgment modes, the oil return circulation mode can be entered when only one of the following occurs: "the current frequency value of compressor 100 is lower than the preset frequency value, and the running time reaches the first preset time". Alternatively, the oil return circulation mode can be entered when only one of the following occurs: "the current oil level is lower than the preset oil level". Or, the oil return circulation mode can be entered only when both "the current frequency value of compressor 100 is lower than the preset frequency value, and the running time reaches the first preset time" and "the current oil level is lower than the preset oil level" occur simultaneously.

[0114] In some embodiments, the controller is configured to: after entering the exit judgment mode, determine whether it is currently in the oil return cycle mode; if so, exit the oil return cycle mode; otherwise, maintain the current state.

[0115] Furthermore, after exiting the oil return circulation mode, it re-enters the operating mode it was in before the oil return circulation mode.

[0116] It is worth noting that if the user issues a new running mode command, the new running mode command will be used.

[0117] In some embodiments, an expansion valve is provided between the indoor heat exchanger 150 and the outdoor heat exchanger 110. The controller is configured to control the expansion valve to increase its opening degree upon entering the oil return circulation mode. This scheme increases the expansion valve opening degree when entering the oil return circulation mode, controlling the suction and discharge superheat to a target value, thereby controlling the refrigerant state in the superheated online gas line to a two-phase state. Furthermore, this design can reduce refrigerant flow resistance and accelerate refrigerant flow rate. This design helps enhance the refrigerant's flushing ability, further promotes lubricant return, and optimizes the system's cooling or heating performance.

[0118] In some embodiments, the air conditioner further includes a first detector and a second detector. The first detector is used to detect the suction superheat of the compressor 100; the second detector is used to detect the discharge superheat of the compressor 100.

[0119] Specifically, the opening degree of the expansion valve is determined based on the current intake superheat and / or exhaust superheat. The greater the difference between the intake superheat and the preset intake superheat value, the greater the opening degree of the corresponding expansion valve. Similarly, the greater the difference between the exhaust superheat and the preset exhaust superheat value, the greater the opening degree of the corresponding expansion valve.

[0120] Furthermore, the controller is configured to, upon entering the oil return circulation mode, control a first detector to detect the suction superheat of the compressor 100; and adjust the expansion valve to the corresponding opening degree based on the suction superheat value. And / or, control a second detector to detect the discharge superheat of the compressor 100; and adjust the expansion valve to the corresponding opening degree based on the discharge superheat value.

[0121] Furthermore, the intake superheat value and the corresponding expansion valve opening can be preset at the factory or distributed via the network or cloud. The exhaust superheat value and the corresponding expansion valve opening can also be preset at the factory or distributed via the network or cloud.

[0122] In some embodiments, the air conditioner is also equipped with an indoor temperature sensor, which is used to detect the indoor return air temperature value of the corresponding indoor unit.

[0123] In some embodiments, the controller is configured to, after entering the oil return circulation mode, calculate the difference between the indoor return air temperature value and the currently set temperature value. If the difference is greater than a threshold, a preset frequency increment is added to the current frequency value of the compressor 100 to obtain the operating frequency value, and the compressor 100 is controlled to operate at the operating frequency value.

[0124] The above solution addresses the issue that changes in the refrigerant state of the indoor unit lead to variations in its capacity. Therefore, by adjusting the compressor frequency (100Hz) according to the indoor heat load, the system ensures that the current operating temperature reaches the required set temperature. Furthermore, this design ensures the normal operation of the oil return circulation mode while dynamically adjusting the compressor frequency (100Hz) based on indoor temperature requirements, preventing lubricant migration issues caused by excessively low frequencies, and simultaneously improving system comfort and energy efficiency.

[0125] Specifically, the controller is configured to, upon entering the oil return circulation mode, control the indoor temperature sensor to detect and acquire the indoor return air temperature value of the corresponding indoor unit. It calculates the difference between the indoor return air temperature value and the currently set temperature value, and determines whether the difference is greater than a threshold. If not, it maintains the current state; if so, it adds a preset frequency increment to the current frequency value of the compressor 100 to obtain the operating frequency value, and controls the compressor 100 to operate at the operating frequency value.

[0126] In some embodiments, the preset frequency is increased to a factory preset or distributed via the cloud.

[0127] In some embodiments, the controller is configured to: after entering the oil return circulation mode, determine the operating mode of the air conditioner when entering the oil return circulation mode. Typically, this is either cooling mode or heating mode.

[0128] In some embodiments, the controller is configured to connect the first port and the third port, and the second port and the fourth port of the four-way valve 900 in cooling mode. Through this scheme, in cooling mode, the refrigerant output from the compressor 100 enters the outdoor heat exchanger 110 through the first and third ports of the four-way valve 900. After cooling in the outdoor heat exchanger 110, the refrigerant enters the indoor heat exchanger 150 to cool the indoor unit. After cooling the indoor unit, the refrigerant flows back to the compressor 100 through the fourth and second ports of the four-way valve 900, ensuring that the refrigerant flows according to the refrigeration cycle path. This design provides a basic refrigerant flow path for the oil return circulation mode, ensuring coordinated operation of the oil return process and the refrigeration cycle, and avoiding oil return failure caused by a chaotic refrigerant flow path.

[0129] In some embodiments, the controller is configured to connect the first port and the fourth port, and the second port and the third port of the four-way valve 900 in heating mode. Through this scheme, in heating mode, the refrigerant output from the compressor 100 enters the indoor heat exchanger 150 through the first and fourth ports of the four-way valve 900 to heat the indoor unit. After heating, the refrigerant enters the outdoor heat exchanger 110 and flows back to the compressor 100 through the third and second ports of the four-way valve 900, ensuring that the refrigerant flows along the path of the heating cycle. This design provides a basic refrigerant flow path for the oil return circulation mode, ensuring coordinated operation of the oil return process and the heating cycle, and avoiding oil return failure caused by a chaotic refrigerant flow path.

[0130] In some embodiments, the controller is configured to re-enter the judgment mode when the intake superheat value is lower than the preset intake superheat value and the duration exceeds a second preset time.

[0131] Furthermore, the controller is configured to: after entering the oil return circulation mode; control the first detector to detect the suction superheat of the compressor 100, obtain the suction superheat value detected by the first detector; determine whether the suction superheat value is lower than a preset suction superheat value; if not, maintain the current state; if so, determine the duration. During the duration determination, determine whether the duration for which the suction superheat value is lower than the preset suction superheat value is greater than a second preset time; if not, maintain the current state; if so, re-enter the determination mode.

[0132] Excessive suction superheat indicates poor heat exchange, possibly due to lubricating oil in the refrigerant. Therefore, the oil return circulation mode is maintained. When the suction superheat drops below the preset value and remains below it for a certain period, it indicates normal heat exchange, and the lubricating oil in the high-pressure and low-pressure lines may have been flushed out. However, for safety, the system re-enters the judgment mode to reassess. Only when it is confirmed that there is no lubricating oil in the lines, or that a small amount of lubricating oil has no significant impact on the air conditioner, is the oil return circulation mode completely exited. This judgment process employs rigorous logic to minimize the possibility of misjudgment.

[0133] In some embodiments, the controller is configured to re-enter the judgment mode when the exhaust superheat value is lower than the preset exhaust superheat value and the duration exceeds a third preset time.

[0134] Furthermore, the controller is configured to: after entering the oil return circulation mode; control the second detector to detect the exhaust superheat of compressor 100, obtain the exhaust superheat value detected by the second detector; determine whether the exhaust superheat value is lower than the preset exhaust superheat value; if so, determine the duration; if the duration is greater than a third preset time, exit the oil return circulation mode. Excessive exhaust superheat also indicates poor heat exchange performance, possibly due to the presence of lubricating oil in the refrigerant, therefore, the oil return circulation state is maintained. When the exhaust superheat decreases to below the preset exhaust superheat value and can be maintained for a certain period, it indicates that the current heat exchange performance is normal, and the lubricating oil in the high-pressure and low-pressure pipelines may have been flushed clean. However, for safety reasons, the judgment mode is re-entered to re-judge, and only when it is confirmed that there is no lubricating oil in the pipeline, or that a small amount of lubricating oil has no significant impact on the air conditioner, is the oil return circulation mode completely exited. The judgment process is logically rigorous, reducing the possibility of misjudgment.

[0135] It is worth noting that the controller is configured to directly re-enter the judgment mode when the "inhalation superheat value is lower than the preset inhalation superheat value and the duration exceeds the second preset time". Alternatively, it can directly re-enter the judgment mode when the "exhaust superheat value is lower than the preset exhaust superheat value and the duration exceeds the third preset time". Furthermore, it can re-enter the judgment mode only when both the "inhalation superheat value is lower than the preset inhalation superheat value and the duration exceeds the second preset time" and "exhaust superheat value is lower than the preset exhaust superheat value and the duration exceeds the third preset time" conditions are met simultaneously.

[0136] In some embodiments, the regenerator 400 includes a first channel and a second channel, with the first pipe 200 connected to the first channel in the middle and the second pipe 300 connected to the second channel in the middle, thereby realizing heat exchange of the refrigerant in the first pipe 200 and the second pipe 300.

[0137] Please refer to Figures 7 to 11 In a second aspect, this application also provides an air conditioner that differs from the air conditioner in the first aspect in that it omits the first valve 500, the second valve 600, the third valve 700, and the fourth valve 800, replacing them with a first three-way valve 170 and a second three-way valve 180. The first three-way valve 170 is located at the connection between the first pipeline 200 and the high-pressure pipeline. The second three-way valve 180 is located at the connection between the second pipeline 300 and the low-pressure pipeline.

[0138] More specifically, the first three-way valve 170 is located at the connection between the high-pressure pipeline and the input end of the first pipeline 200. The second three-way valve 180 is located at the connection between the low-pressure pipeline and the input end of the second pipeline 300.

[0139] The controller is configured to, upon entering the oil return circulation mode, control the first three-way valve 170 to connect the compressor 100 and the four-way valve 900 through the first pipeline 200; and control the second three-way valve 180 to connect the compressor 100 and the four-way valve 900 through the second pipeline 300.

[0140] Through the above scheme, by installing a regenerator 400 between the high-pressure and low-pressure pipelines, and connecting the first pipeline 200 and the second pipeline 300 in parallel, and controlling the opening and closing of the first three-way valve 170 and the second three-way valve 180, heat exchange between the high-pressure and low-pressure refrigerants can be achieved using the regenerator 400 when entering the oil return circulation mode. This design allows the high-temperature, high-pressure refrigerant discharged from the compressor 100 to exchange heat with the low-temperature, low-pressure refrigerant, condensing into a high-temperature, high-pressure two-phase refrigerant. The formation of the two-phase refrigerant enhances the refrigerant's flushing ability, thereby effectively promoting the return of lubricating oil from the system to the compressor 100, avoiding the oil shortage problem of the compressor 100 caused by low-frequency operation.

[0141] The above solution uses two three-way valves to replace the first valve 500, the second valve 600, the third valve 700, and the fourth valve 800 in the first solution, which saves costs.

[0142] It is worth noting that the air conditioner in the second aspect and the air conditioner in the first aspect can be completely identical in structure and controller configuration, except for the valves used and the control methods at the corresponding valves.

[0143] Please refer to Figures 12 to 15 Thirdly, this application also provides an air conditioner, which includes a compressor 100, an outdoor heat exchanger 110, and an indoor heat exchanger 150. One end of the outdoor heat exchanger 110 is connected to the compressor 100. Refrigerant is supplied to the outdoor heat exchanger 110 and the indoor heat exchanger 150 through the compressor 100.

[0144] In some embodiments, the air conditioner further includes a refrigerant line 190 for communication between the outdoor heat exchanger 110 and the indoor heat exchanger 150. Refrigerant entering the outdoor heat exchanger 110 enters the indoor heat exchanger 150 through the refrigerant line 190.

[0145] In some embodiments, the air conditioner further includes a low-pressure line for connecting the indoor heat exchanger 150 to the compressor 100. Normally, the refrigerant entering the indoor heat exchanger 150 from the outdoor heat exchanger 110 flows back to the compressor 100 via the low-pressure line.

[0146] In some embodiments, the air conditioner further includes a regenerator 400 disposed between the refrigerant line 190 and the low-pressure line, which is used for heat exchange between the refrigerant line 190 and the low-pressure line. Its principle is the same as that of the heat exchanger in the first aspect, which is used to cool down the high-pressure refrigerant in the refrigerant line 190 into a gas-liquid two-phase refrigerant and flush the line.

[0147] In some embodiments, the air conditioner further includes an expansion valve disposed on the refrigerant line 190 and located on the side of the regenerator 400 near the indoor heat exchanger 150. In cooling mode, the high-temperature refrigerant passing through the outdoor heat exchanger 110 is converted into low-pressure refrigerant through the expansion valve and then enters the indoor heat exchanger 150.

[0148] In some embodiments, the air conditioner further includes a controller configured to control the expansion valve to increase its opening degree after entering the oil return circulation mode.

[0149] Through the above scheme, the refrigerant in the section of refrigerant pipeline 190 located between the outdoor heat exchanger 110 and the expansion valve is the high-temperature, high-pressure gaseous refrigerant output from the compressor 100. The refrigerant in the low-pressure pipeline is a low-temperature liquid refrigerant. When passing through the regenerator 400, the refrigerant in the refrigerant pipeline 190 is cooled by the refrigerant in the low-pressure pipeline, causing the refrigerant in the refrigerant pipeline 190 to become a two-phase refrigerant mixture. The formation of the two-phase refrigerant enhances the refrigerant's flushing ability, thereby effectively promoting the return of lubricating oil from the system to the compressor 100, avoiding the oil shortage problem in the compressor 100 caused by low-frequency operation.

[0150] In some embodiments, the controller is configured to directly enter the oil return circulation mode upon receiving a control signal. Because the compressor 100 starts when the air conditioner is turned on, and the compressor 100 typically carries a large amount of lubricating oil into the pipeline when outputting refrigerant, directly entering the oil return circulation mode can directly flush the lubricating oil in the pipeline, allowing the lubricating oil to flow back to the compressor 100. This method ensures that the compressor 100 does not experience oil shortage each time the air conditioner is turned on.

[0151] In some embodiments, an expansion valve is provided between the indoor heat exchanger 150 and the outdoor heat exchanger 110. The controller is configured to control the expansion valve to increase its opening degree upon entering the oil return circulation mode. This scheme increases the expansion valve opening degree when entering the oil return circulation mode, controlling the suction and discharge superheat to a target value, thereby controlling the refrigerant state in the superheated online gas line to a two-phase state. Furthermore, this design can reduce refrigerant flow resistance and accelerate refrigerant flow rate. This design helps enhance the refrigerant's flushing ability, further promotes lubricant return, and optimizes the system's cooling or heating performance.

[0152] In some embodiments, the air conditioner further includes a first detector and a second detector. The first detector is used to detect the suction superheat of the compressor 100; the second detector is used to detect the discharge superheat of the compressor 100.

[0153] Specifically, the opening degree of the expansion valve is determined based on the current intake superheat and / or exhaust superheat. The greater the difference between the intake superheat and the preset intake superheat value, the greater the opening degree of the corresponding expansion valve. Similarly, the greater the difference between the exhaust superheat and the preset exhaust superheat value, the greater the opening degree of the corresponding expansion valve.

[0154] Furthermore, the controller is configured to, upon entering the oil return circulation mode, control a first detector to detect the suction superheat of the compressor 100; acquire the suction superheat value detected by the first detector; and adjust the expansion valve to the corresponding opening degree based on the suction superheat value. And / or, control a second detector to detect the discharge superheat of the compressor 100; and adjust the expansion valve to the corresponding opening degree based on the discharge superheat value.

[0155] Furthermore, the intake superheat value and the corresponding expansion valve opening can be preset at the factory or distributed via the network or cloud. The exhaust superheat value and the corresponding expansion valve opening can also be preset at the factory or distributed via the network or cloud.

[0156] In some embodiments, the air conditioner is also equipped with an indoor temperature sensor, which is used to detect the indoor return air temperature value of the corresponding indoor unit.

[0157] In some embodiments, the controller is configured to, after entering the oil return circulation mode, calculate the difference between the indoor return air temperature value and the currently set temperature value. If the difference is greater than a threshold, a preset frequency increment is added to the current frequency value of the compressor 100 to obtain the operating frequency value, and the compressor 100 is controlled to operate at the operating frequency value.

[0158] The above solution addresses the issue that changes in the refrigerant state of the indoor unit lead to variations in its capacity. Therefore, by adjusting the compressor frequency (100Hz) according to the indoor heat load, the system ensures that the current operating temperature reaches the required set temperature. Furthermore, this design ensures the normal operation of the oil return circulation mode while dynamically adjusting the compressor frequency (100Hz) based on indoor temperature requirements, preventing lubricant migration issues caused by excessively low frequencies, and simultaneously improving system comfort and energy efficiency.

[0159] Specifically, the controller is configured to, upon entering the oil return circulation mode, control the indoor temperature sensor to detect and acquire the indoor return air temperature value of the corresponding indoor unit. It calculates the difference between the indoor return air temperature value and the currently set temperature value, and determines whether the difference is greater than a threshold. If not, it maintains the current state; if so, it adds a preset frequency increment to the current frequency value of the compressor 100 to obtain the operating frequency value, and controls the compressor 100 to operate at the operating frequency value.

[0160] In some embodiments, the preset frequency is increased to a factory preset or distributed via the cloud.

[0161] In some embodiments, the air conditioner further includes a four-way valve 900, which includes a first interface, a second interface, a third interface, and a fourth interface; the first interface is connected to the output end of the compressor 100, the second interface is connected to the input end of the compressor 100, the third interface is connected to the outdoor heat exchanger 110, and the fourth interface is connected to the end of the regenerator 400 in the low-pressure pipeline away from the indoor heat exchanger 150.

[0162] In some embodiments, the controller is configured to: after entering the oil return circulation mode, determine the operating mode of the air conditioner when entering the oil return circulation mode. Typically, this is either cooling mode or heating mode.

[0163] In some embodiments, the controller is configured to: in cooling mode, connect the first and third ports of the four-way valve 900, and connect the second and fourth ports; in heating mode, connect the first and fourth ports, and connect the second and third ports.

[0164] With this design, in cooling mode, the refrigerant enters the outdoor heat exchanger 110 through the first and third ports, passes through the indoor heat exchanger 150, and then flows back to the compressor 100 via the fourth and second ports. In heating mode, the refrigerant enters the indoor heat exchanger 150 through the first and fourth ports, passes through the outdoor heat exchanger 110, and then flows back to the compressor 100 via the third and first ports. In both heating and cooling modes, the refrigerant can pass through the regenerator 400, achieving the effect of flushing the pipes.

[0165] In some embodiments, the controller is configured to re-enter the judgment mode when the intake superheat value is lower than the preset intake superheat value and the duration exceeds a second preset time.

[0166] Furthermore, the controller is configured to: after entering the oil return circulation mode; control the first detector to detect the suction superheat of the compressor 100, obtain the suction superheat value detected by the first detector; determine whether the suction superheat value is lower than a preset suction superheat value; if not, maintain the current state; if so, determine the duration. During the duration determination, determine whether the duration for which the suction superheat value is lower than the preset suction superheat value is greater than a second preset time; if not, maintain the current state; if so, re-enter the determination mode.

[0167] Excessive suction superheat indicates poor heat exchange, possibly due to lubricating oil in the refrigerant. Therefore, the oil return circulation mode is maintained. When the suction superheat drops below the preset value and remains there for a certain period, it indicates normal heat exchange, and the lubricating oil in the pipes may have been flushed out. However, for safety, the system re-enters the judgment mode to reassess. Only when it is confirmed that there is no lubricating oil in the pipes, or that a small amount of lubricating oil has little impact on the air conditioner, is the oil return circulation mode completely exited. This judgment process employs rigorous logic to minimize the possibility of misjudgment.

[0168] In some embodiments, the controller is configured to re-enter the judgment mode when the exhaust superheat value is lower than the preset exhaust superheat value and the duration exceeds a third preset time.

[0169] Furthermore, the controller is configured to: after entering the oil return circulation mode; control the second detector to detect the exhaust superheat of compressor 100, obtain the exhaust superheat value detected by the second detector; determine whether the exhaust superheat value is lower than the preset exhaust superheat value; if so, determine the duration; if the duration is greater than a third preset time, exit the oil return circulation mode. Excessive exhaust superheat also indicates poor heat exchange performance, possibly due to lubricating oil in the refrigerant, therefore the oil return circulation state continues. When the exhaust superheat decreases to below the preset exhaust superheat value and can be maintained for a certain period, it indicates that the current heat exchange performance is normal, and the lubricating oil in the pipeline may have been flushed clean. However, for safety reasons, the judgment mode is re-entered to re-judge, and only when it is confirmed that there is no lubricating oil in the pipeline, or that a small amount of lubricating oil has no significant impact on the air conditioner, is the oil return circulation mode completely exited. The judgment process is logically rigorous, reducing the possibility of misjudgment.

[0170] It is worth noting that the controller is configured to directly re-enter the judgment mode when the "inhalation superheat value is lower than the preset inhalation superheat value and the duration exceeds the second preset time". Alternatively, it can directly re-enter the judgment mode when the "exhaust superheat value is lower than the preset exhaust superheat value and the duration exceeds the third preset time". Furthermore, it can re-enter the judgment mode only when both the "inhalation superheat value is lower than the preset inhalation superheat value and the duration exceeds the second preset time" and "exhaust superheat value is lower than the preset exhaust superheat value and the duration exceeds the third preset time" conditions are met simultaneously.

[0171] In some embodiments, the air conditioner in the third aspect differs from the air conditioner in the first aspect only in that the regenerator 400 is positioned between the indoor heat exchanger 150 and the outdoor heat exchanger 110, and the rest is the same as the air conditioner in the first aspect.

[0172] Please refer to Figure 16 and Figure 17 Fourthly, this application also provides an air conditioner that differs from the air conditioner in the third aspect in that it further includes a heat recovery passage 210, which is connected in parallel with the refrigerant pipeline 190. A regenerator 400 is disposed between the heat recovery passage 210 and the connecting pipeline 220, and is used for heat exchange between the heat recovery passage 210 and the connecting pipeline 220.

[0173] In some embodiments, the air conditioner further includes a valve module 230, which is used to open or close the regeneration passage 210 to allow refrigerant to pass through the refrigerant line 190 or through the regeneration passage 210. The controller is configured to control the valve module 230 to open the regeneration passage 210 after entering the oil return circulation mode, so that refrigerant passes through the regeneration passage 210.

[0174] In the above solution, the valve module 230 allows users to select whether the refrigerant flows through the regenerator 400, enabling them to choose whether to activate the oil return circulation mode. This meets the user's needs in different scenarios, enhances the flexibility and applicability of the air conditioner, and provides users with a more personalized and efficient user experience.

[0175] In some embodiments, the section of refrigerant pipeline 190 between the two ends of the regenerator passage 210 is a high-pressure section; valve module 230 is used to open the high-pressure section and close the regenerator passage 210, or close the high-pressure section and open the regenerator passage 210. When not in oil return circulation mode, the high-pressure section is opened and the regenerator passage 210 is closed. The refrigerant flows directly through the pipeline. When entering oil return circulation mode, the regenerator passage 210 is opened, and all or part of the refrigerant flows through the regenerator passage 210 and exchanges heat with the connecting pipeline 220 in the regenerator 400, so that the refrigerant passing through the regenerator passage becomes a two-phase refrigerant. This structural design eliminates unnecessary pipelines, saving costs.

[0176] Furthermore, the controller is configured to, upon entering the oil return circulation mode, control valve module 230 to open the regenerative passage 210 while closing the high-pressure section, to ensure that all refrigerant passes through the regenerative passage 210, thereby increasing the content of the two-phase refrigerant.

[0177] In some embodiments, the valve module 230 can be two solenoid valves, which are respectively located in the regenerative passage 210 and the high-pressure section. The switching between the regenerative passage 210 and the high-pressure section is achieved by controlling the solenoid valves.

[0178] In some embodiments, the valve module 230 can be a three-way valve, which is located at the connection between the refrigerant line 190 and the inlet of the regenerative passage 210, and switches between the high-pressure section and the regenerative passage 210.

[0179] In some embodiments, the air conditioner further includes an expansion valve disposed in the regenerative passage 210 and on the side of the regenerator 400 near the indoor heat exchanger 150. The controller is configured to control the expansion valve to increase its opening degree after entering the oil return circulation mode.

[0180] This design increases the opening of the expansion valve when entering the oil return circulation mode, controlling the superheat of the intake and exhaust gases to the target value. This aims to bring the refrigerant in the overheated online gas lines into a two-phase state. Furthermore, this design reduces refrigerant flow resistance and accelerates refrigerant flow rate. This design helps enhance the refrigerant's flushing ability, further promotes lubricating oil return, and optimizes the system's cooling or heating performance.

[0181] In some embodiments, because a valve module 230 is provided, the user can choose whether to enter the oil return circulation mode as needed. Therefore, a judgment mode is provided to determine whether to enter the oil return circulation mode.

[0182] The specific solution is that the controller is configured to enter a judgment mode upon receiving a control signal. The control signal can be a power-on signal or a compressor 100 start signal; that is, the judgment mode is entered immediately after the air conditioner is turned on. Because when the air conditioner is turned on, the compressor 100 starts, and when it outputs refrigerant, it usually carries a large amount of lubricating oil into the piping (in this article, refrigerant piping, high-pressure piping, low-pressure piping, etc., used for refrigerant flow are all referred to as piping). Therefore, activating the judgment mode upon startup allows for a quicker transition to the oil return circulation mode, improving the protection of the air conditioner.

[0183] Furthermore, the power-on signal specifically refers to the power-on signal of any one indoor unit.

[0184] In some embodiments, the control signal can specifically be a remote control signal, a Bluetooth signal, or a network signal. That is, the user can enter the judgment mode using a remote control, mobile phone, cloud download, WIFI (wireless communication technology), etc. The judgment mode is used to detect whether the air conditioner compressor 100 is short of oil. If it is short of oil, it can directly enter the oil return circulation mode to improve the oil shortage situation of the compressor 100.

[0185] In some embodiments, the controller is configured to, upon entering a judgment mode, acquire the current frequency value of the compressor 100. If the current frequency value of the compressor 100 is lower than a preset frequency value and the running time reaches a first preset time, then it enters the oil return circulation mode. When the frequency of the compressor 100 is lower than the preset value and the running time reaches the first preset time, there may be a situation where the lubricating oil is in the pipeline and the compressor 100 has insufficient lubricating oil. This frequency and time-based detection logic can accurately determine whether the compressor 100 is in a low-frequency operating state, thereby promptly initiating the oil return circulation mode to prevent lubricating oil from accumulating in the system and ensuring normal lubrication of the compressor 100.

[0186] Furthermore, a control unit is installed inside the compressor 100. After entering the judgment mode, the specific steps for obtaining the compressor 100 frequency are as follows: the controller directly obtains the current frequency value of the compressor 100 from the control unit. This method provides a more intuitive and accurate result.

[0187] In some embodiments, the air conditioner further includes a compressor detection unit, which is used to detect the current frequency of the compressor 100. After entering the judgment mode, the specific steps for obtaining the compressor 100 frequency are as follows: controlling the compressor detection unit to detect the current frequency of the compressor 100 and obtain the current frequency value; and the control unit obtaining the current frequency value.

[0188] Specifically, the controller is configured to: upon entering the judgment mode, acquire the current frequency value of compressor 100, determine whether the current frequency value of compressor 100 is lower than a preset frequency value; if not, enter the exit judgment mode. If yes, acquire the continuous running time of compressor 100 at a frequency lower than the preset value, determine whether the running time exceeds a first preset time; if not, enter the exit judgment mode. If yes, enter the oil return circulation mode.

[0189] It is worth noting that while obtaining the current frequency value of compressor 100, the continuous running time of compressor 100 at a frequency lower than the preset value can also be obtained directly.

[0190] Specifically, when the controller obtains the current frequency value through the control unit in the compressor 100, the controller obtains the aforementioned operating time through the control unit in the compressor 100.

[0191] When the controller obtains the current frequency value through the compressor detection unit, the compressor detection unit records the operating time of compressor 100 when the current frequency value is lower than the preset frequency value. The controller obtains the above operating time through the compressor detection unit.

[0192] In another embodiment, the controller is configured to start calculating the duration of operation when the current frequency value of the compressor 100 is lower than the preset frequency value, so that it can be obtained immediately after the judgment mode is activated.

[0193] In some embodiments, an oil level sensor is installed inside the compressor 100. The controller is configured to: upon entering a judgment mode, control the oil level sensor to detect the current oil level; if the current oil level is lower than a preset oil level, enter the oil return circulation mode. By installing an oil level sensor inside the compressor 100, the oil level inside the compressor 100 is directly detected. When the oil level is lower than the preset value, it is determined that the lubricating oil content inside the compressor 100 is low, and the oil return circulation mode needs to be entered. This design can directly monitor the oil level status inside the compressor 100, and its judgment is accurate, enabling timely entry into the oil return circulation mode, avoiding wear or burnout of the compressor 100 due to excessively low oil levels, while improving the system's response speed and reliability.

[0194] Furthermore, the controller is configured to: upon entering the judgment mode, control the oil level sensor to detect the current oil level and acquire the current oil level value detected by the sensor. It then determines whether the current oil level is lower than a preset oil level; if not, it exits the judgment mode. If so, it enters the return oil circulation mode.

[0195] It is worth noting that, in the above two judgment modes, the oil return circulation mode can be entered when only one of the following occurs: "the current frequency value of compressor 100 is lower than the preset frequency value, and the running time reaches the first preset time". Alternatively, the oil return circulation mode can be entered when only one of the following occurs: "the current oil level is lower than the preset oil level". Or, the oil return circulation mode can be entered only when both "the current frequency value of compressor 100 is lower than the preset frequency value, and the running time reaches the first preset time" and "the current oil level is lower than the preset oil level" occur simultaneously.

[0196] In some embodiments, the controller is configured to: after entering the exit judgment mode, determine whether it is currently in the oil return cycle mode; if so, exit the oil return cycle mode; otherwise, maintain the current state.

[0197] Furthermore, after exiting the oil return circulation mode, it re-enters the operating mode it was in before the oil return circulation mode.

[0198] It is worth noting that if the user issues a new running mode command, the new running mode command will be used.

[0199] In some embodiments, the other structural schemes and control methods of the air conditioner in the fourth aspect are the same as those of the air conditioner in the third aspect.

[0200] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. An air conditioner, characterized in that, It includes: compressor; An outdoor heat exchanger, one end of which is connected to the compressor; Indoor heat exchanger; Refrigerant piping, which is used for the connection between the outdoor heat exchanger and the indoor heat exchanger; A low-pressure pipeline is used to connect the indoor heat exchanger to the compressor; A regenerator is provided between the refrigerant pipeline and the low-pressure pipeline for heat exchange between the refrigerant pipeline and the low-pressure pipeline; An expansion valve is provided in the refrigerant line and located on the side of the regenerator closer to the indoor heat exchanger. The controller is configured to control the expansion valve to increase the opening channel after entering the return oil circulation mode.

2. The air conditioner according to claim 1, characterized in that, It also includes: The four-way valve includes a first port, a second port, a third port, and a fourth port; the first port is connected to the output end of the compressor, the second port is connected to the input end of the compressor, the third port is connected to the outdoor heat exchanger, and the fourth port is connected to the end of the regenerator in the low-pressure pipeline away from the indoor heat exchanger.

3. The air conditioner according to claim 2, characterized in that, The controller is configured to: After entering the judgment mode: The frequency of the compressor is obtained. If the frequency of the compressor is lower than the preset frequency value and the running time reaches the first preset time, the oil return circulation mode is entered.

4. The air conditioner according to claim 2, characterized in that, The compressor is equipped with an oil level sensor. The controller is configured to: after entering the judgment mode, control the oil level sensor to detect the current oil level; if the current oil level is lower than the preset oil level, enter the oil return circulation mode.

5. The air conditioner according to claim 1, characterized in that, An indoor temperature sensor is also installed to detect the indoor return air temperature. The controller is configured to calculate the difference between the indoor return air temperature and the currently set temperature. If the difference is greater than a threshold, a preset frequency increment is added to the current compressor frequency to obtain the operating frequency value, and the compressor is controlled to operate at the operating frequency value.

6. The air conditioner according to claim 1, characterized in that, It also includes: A first detector is used to detect the suction superheat of the compressor; The controller is configured to: after entering the oil return circulation mode; control the first detector to detect the suction superheat of the compressor and obtain the suction superheat value; determine whether the suction superheat value is lower than the preset suction superheat value, and if so, determine the duration; During the duration determination, it is determined whether the duration during which the inhalation superheat value is lower than the preset inhalation superheat value is greater than the second preset time. If not, the current state is maintained; if so, the determination mode is re-entered.

7. The air conditioner according to claim 1, characterized in that, It also includes: The second detector is used to detect the exhaust superheat of the compressor; The controller is configured to: after entering the oil return circulation mode; control the second detector to detect the exhaust superheat of the compressor and obtain the exhaust superheat value; determine whether the exhaust superheat value is lower than the preset exhaust superheat value, and if so, determine the duration; During the duration determination, it is determined whether the duration for which the exhaust superheat value is lower than the preset exhaust superheat value is greater than the third preset time. If not, the current state is maintained; if so, the determination mode is re-entered.

8. An air conditioner, characterized in that, It includes: compressor; An outdoor heat exchanger, one end of which is connected to the compressor; Indoor heat exchanger; Refrigerant piping, which is used for the connection between the outdoor heat exchanger and the indoor heat exchanger; A connecting pipe, wherein the connecting pipe is used to connect the indoor heat exchanger to the compressor; A heat recovery passage, which is connected in parallel with the refrigerant pipeline; A regenerator is disposed between the regenerating passage and the connecting pipe, and is used for heat exchange between the regenerating passage and the connecting pipe; A valve module, which is used to open or close the regeneration passage to allow refrigerant to pass through the refrigerant pipeline or through the regeneration passage; The controller is configured to, upon entering the oil return circulation mode, control the valve module to open the regenerative passage so that the refrigerant passes through the regenerative passage.

9. The air conditioner according to claim 8, characterized in that, The section of the refrigerant pipeline located between the two ends of the heat recovery passage is a high-pressure section. The valve module is used to open the high-pressure section and close the regenerative passage, or close the high-pressure section and open the regenerative passage.

10. The air conditioner according to claim 8, characterized in that, Also includes: An expansion valve is disposed in the regenerative passage and located on the side of the regenerator closer to the indoor heat exchanger; The controller is configured to control the expansion valve to increase the opening degree of the expansion valve after entering the return oil circulation mode.

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