Air conditioner and oil return operation control method thereof

Abstract

This invention relates to the field of air conditioning equipment technology, and more particularly to an air conditioner and its oil return operation control method. The method divides the operating frequency range of the air conditioner compressor into three frequency ranges, and further divides the compressor oil return operation stage into an oil return operation preparation stage and a formal oil return operation stage. This scheme controls the three frequency ranges separately, enabling the formulation of different operating time limits for the compressor in the three different frequency ranges. It also allows for different compressor oil return operation strategies based on different indoor temperature differences ΔT. The compressor oil return operation frequency is lower when ΔT is smaller than when ΔT is larger, thus avoiding excessive output of cooling or heating by the air conditioner when the temperature difference between the indoor temperature and the set temperature is too small, resulting in excessively low indoor temperatures (during cooling operation) or excessively high indoor temperatures (during heating operation), thereby affecting indoor thermal comfort.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of air conditioning equipment, in particular to an air conditioner and an oil return operation control method thereof. BACKGROUND

[0002] During the working process of the air conditioner, the compressor lubricating oil is discharged from the compressor along with the compressor exhaust gas flow.

[0003] When the compressor is in a low-frequency operation state for a long time, the refrigerant flow rate in the refrigerant pipeline is low, and the lubricating oil discharged from the compressor cannot be effectively brought back to the compressor. If the compressor operates in this state for too long, it may affect the operation reliability of the compressor, and in severe cases, it may cause the compressor to burn out.

[0004] The existing compressor oil return operation control scheme is to limit the time of low-frequency operation of the compressor. When the compressor operates at a low frequency for a period of time, the operating frequency of the compressor is increased to a certain set frequency for a period of time, and the compressor lubricating oil is brought back to the inside of the compressor. However, this control method will cause excessive refrigeration or heating output, causing fluctuations in the indoor environment temperature and affecting the comfort during use of the air conditioner. SUMMARY

[0005] In order to solve the above problems, the purpose of the present application is to provide an air conditioner and an oil return operation control method thereof, which can solve the problem of excessive refrigeration or heating output during the oil return operation of the air conditioner, thereby reducing the indoor comfort or causing the air conditioner to stop operating.

[0006] In order to achieve the above purpose, the present application adopts the following technical scheme:

[0007] An oil return operation control method of an air conditioner is applied to an air conditioner, which includes a controller, an indoor unit and an outdoor unit. The method is characterized in that:

[0008] The indoor unit includes an indoor heat exchanger, an indoor environment temperature sensor, an indoor heat exchanger temperature sensor, an indoor fan, an indoor control mechanism and a supply air direction adjusting mechanism.

[0009] The outdoor unit includes a compressor, a four-way reversing valve, an outdoor heat exchanger, an outdoor fan, a throttling mechanism for controlling flow and an outdoor control mechanism. The indoor heat exchanger and the outdoor heat exchanger form a loop through a first refrigerant linking pipeline and a second refrigerant linking pipeline. The compressor and the throttling mechanism are arranged in the above-mentioned loop. The four-way reversing valve is used to switch valve ports so that the air conditioner has a cooling mode and a heating mode. The controller includes the indoor control mechanism and the outdoor control mechanism. The control method comprises the following steps:

[0010] S1: The air conditioner receives the operation parameters set by the user, and the controller obtains the operation frequency F of the compressor; the obtained operation frequency F of the compressor is compared with the preset first determination threshold a of the operation frequency of the compressor;

[0011] If F < a, the controller counts the duration ta of the operation frequency of the compressor being less than the first determination threshold a, and if ta > c, X = 1, and the air conditioner enters the oil return operation preparation stage;

[0012] S2: The controller judges whether ta is greater than the preset time determination threshold d, and if ta > d, the air conditioner enters the formal oil return operation stage;

[0013] S3: If F ≥ a, the controller continues to compare the obtained operation frequency F of the compressor with the preset second determination threshold b of the operation frequency of the compressor, and if F > b, the controller judges whether the value of the mark X of the operation frequency of the compressor being less than the first determination threshold is equal to 1, and if X = 1, the controller counts the duration tb of the operation frequency of the compressor being greater than the second determination threshold b, and judges whether the duration tb of the operation frequency of the compressor being greater than the second determination threshold b reaches the fourth time determination threshold f, and if tb > f, X = 0, tb = 0, and the air conditioner exits the oil return operation preparation stage and returns to normal operation;

[0014] S4: If a ≤ F ≤ b, the controller counts the duration tab of the operation frequency of the compressor being between the first determination threshold a and the second determination threshold b of the operation frequency of the compressor, and judges whether the duration tab of the operation frequency of the compressor being between the first determination threshold a and the second determination threshold b is greater than the preset time threshold e, and if tab > e, the air conditioner enters the formal oil return operation stage;

[0015] S5: In S2 and S4, the air conditioner enters the formal oil return operation stage, the controller obtains the information of the indoor environment temperature Ti and the set temperature Ts, and calculates the temperature difference AT, and the controller judges whether the calculation result of AT is greater than or equal to the preset temperature difference threshold i;

[0016] If AT ≥ i, the controller sets the operation frequency F of the compressor to be equal to the preset operation frequency h of the compressor, the air conditioner operates according to the preset oil return operation program, and after the oil return operation program is completed, X = 0, ta = 0, tab = 0, and the air conditioner returns to normal operation;

[0017] If AT < i, the controller sets the operation frequency F of the compressor to be equal to the preset operation frequency g of the compressor, the air conditioner operates according to the preset oil return operation program, and after the oil return operation program is completed, X = 0, ta = 0, tab = 0, and the air conditioner returns to normal operation.

[0018] As preferred, in S3, if tb≤f, the air conditioner is in normal operation, the controller acquires the compressor operation frequency F, and judges whether the compressor operation frequency F is less than or equal to the preset frequency threshold b, if F≤b, tb=0, the air conditioner is in normal operation.

[0019] As preferred, in S3, if F>b, X=0, the air conditioner is in normal operation.

[0020] As preferred, in S4, if tab≤e, the air conditioner is in normal operation.

[0021] As preferred, in S2, ta≤d, the air conditioner is in normal operation.

[0022] As preferred, the time judgment threshold e>d>c>f, the compressor operation frequency h>g.

[0023] As preferred, in S5, △T=Ti-Ts when the air conditioner is in cooling operation, and △T=Ts-Ti when the air conditioner is in heating operation.

[0024] As preferred, the indoor control mechanism comprises:

[0025] a user information receiving module adapted to receive the air conditioner operation state setting information set by the user;

[0026] a first operation information acquiring module adapted to acquire the operation information of each device in the indoor unit and the information received by the user information receiving module (1;

[0027] a time acquiring / statistic module adapted to acquire the current date and time, and to count the time length of the operation state of the compressor at each frequency;

[0028] a first information sending / receiving module adapted to communicate with the outdoor control mechanism.

[0029] a first information storage module adapted to store the user setting parameter information received by the air conditioner, and to store various operation states and operation time information in the operation process of the air conditioner;

[0030] an operation state judgment module adapted to judge whether the air conditioner needs to enter or exit the oil return operation according to the current operation state of the air conditioner and the operation time in each state.

[0031] As preferred, the outdoor control mechanism comprises:

[0032] a second information storage module;

[0033] a second information sending / receiving module adapted to communicate information with the indoor control mechanism;

[0034] The operation information acquisition module is adapted to acquire operation information of each device in the outdoor unit and information received by the information sending / receiving module.

[0035] The compressor operation frequency control is adapted to control the operation frequency of the compressor.

[0036] The application discloses an air conditioner and an oil return operation control method of the air conditioner.

[0037] The application adopts the technical scheme, divides the operation frequency range of the compressor of the air conditioner into three frequency ranges (F

[0038] When F

[0039] In the oil return operation preparation stage, if the operation condition meeting the oil return operation of the compressor appears (for example, the operation frequency of the compressor is higher than b and the time lasts for f), the oil return operation preparation stage is exited, the number of times of entering the oil return operation intentionally is reduced, and the energy efficiency is improved.

[0040] In the oil return operation preparation stage, if the operation condition meeting the oil return operation of the compressor appears (for example, the operation frequency of the compressor is higher than b and the time lasts for f), the oil return operation preparation stage is exited, the number of times of entering the oil return operation intentionally is reduced, and the energy efficiency is improved.

[0041] In addition, the compressor enters the formal oil return operation stage after operating for a specific length of time under the condition of a

[0042] The scheme can also formulate different operation limiting times (for example, preset time judgment thresholds d and e) of the compressor under the three different frequency ranges.

[0043] In addition, the scheme can formulate different oil return operation strategies of the compressor according to different indoor temperature differences ΔT, the oil return operation frequency of the compressor is smaller when the indoor temperature difference ΔT is smaller, and the oil return operation frequency of the compressor is larger when the indoor temperature difference ΔT is larger, so that the indoor temperature is not too low (in the refrigeration operation mode) or too high (in the heating operation mode) due to the excessive output of cold or heat of the air conditioner when the temperature difference between the indoor temperature and the set temperature is too small, thereby affecting the indoor thermal comfort. BRIEF DESCRIPTION OF DRAWINGS

[0044] Figure 1 It is a structural schematic diagram of an air conditioner.

[0045] Figure 2 It is a structural schematic diagram of an indoor control mechanism and an outdoor control mechanism.

[0046] Figure 3 The control logic diagram for the oil return operation of the air conditioner in the present case. DETAILED DESCRIPTION

[0047] Embodiments of the present application are described below in detail, examples of which are shown in the drawings, wherein the same or similar notations represent the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary and are intended to explain the present application, and cannot be understood as a limitation of the present application.

[0048] In the description of the present application, it is to be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "clockwise", "counterclockwise" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the purpose of facilitating the description of the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation of the present application.

[0049] In addition, the terms "first", "second" are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more of the features. In the description of the present application, unless otherwise specified, the meaning of "a plurality of" is two or more, unless otherwise explicitly limited.

[0050] In the present application, unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connecting", "fixing" and the like should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium, or it can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0051] In the present application, unless otherwise explicitly specified and limited, "on" or "under" of a first feature to a second feature can include that the first and second features are in direct contact, or that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, "on", "above" and "over" of a first feature to a second feature includes that the first feature is directly above and obliquely above the second feature, or only indicates that the first feature is higher in horizontal height than the second feature. "Under", "below" and "underneath" of a first feature to a second feature includes that the first feature is directly below and obliquely below the second feature, or only indicates that the first feature is lower in horizontal height than the second feature.

[0052] As shown in Fig. 1, an air conditioner 1 comprises a controller, an indoor unit 10 and an outdoor unit 20; Figures 1-2

[0053] The indoor unit 10 comprises an indoor heat exchanger 101, an indoor ambient temperature sensor 102, an indoor heat exchanger temperature sensor 103, an indoor fan 104, an indoor control mechanism 105 and a supply air direction adjusting mechanism;

[0054] The outdoor unit 20 comprises a compressor 201, a four-way reversing valve 202, an outdoor heat exchanger 203, an outdoor fan 204, a throttling mechanism 205 for controlling flow rate and an outdoor control mechanism 206; the indoor heat exchanger 101 and the outdoor heat exchanger 203 form a loop through a first refrigerant linking pipe 30 and a second refrigerant linking pipe 40, the compressor 201 and the throttling mechanism 205 are arranged in the loop, the four-way reversing valve 202 is used to switch valve ports so that the air conditioner has a cooling mode and a heating mode; the controller comprises the indoor control mechanism 105 and the outdoor control mechanism 206.

[0055] Further, the indoor control mechanism 105 comprises:

[0056] a user information receiving module 1051 adapted to receive air conditioner operation state setting information set by a user;

[0057] a first operation information obtaining module 1052 adapted to obtain operation information of each device in the indoor unit 10 and information received by the user information receiving module 1051;

[0058] a time obtaining / counting module 1053 adapted to obtain current date and time and count time length of operation state of the compressor at each frequency;

[0059] a first information sending / receiving module 1054 adapted to communicate with the outdoor control mechanism 207.

[0060] ​The first information storage module 1055 is adapted to store the user set parameter information received by the air conditioner and store various operation states and operation time information during the operation of the air conditioner.

[0061] The operation state judgment module 1056 is adapted to judge whether the air conditioner needs to enter the oil return operation or exit the oil return operation according to the current operation state of the air conditioner and the operation time in each state.

[0062] Further, the outdoor control mechanism 206 comprises:

[0063] The second information storage module 2061;

[0064] The second information sending / receiving module 2064 is adapted to intercommunicate information with the indoor control mechanism 105;

[0065] The operation information acquisition module 2062 is adapted to acquire the operation information of each device in the outdoor unit 20 and the information received by the information sending / receiving module 2064;

[0066] The compressor operation frequency control 2063 is adapted to control the operation frequency of the compressor 201.

[0067] As shown in the air conditioner oil return operation control method, Figure 3 the steps are as follows:

[0068] S1: The air conditioner receives the operation parameters set by the user, the controller acquires the operation frequency F of the compressor, and compares the acquired operation frequency F of the compressor with the first judgment threshold a of the preset operation frequency of the compressor;

[0069] If F < a, the controller counts the duration ta of the operation frequency of the compressor less than the first judgment threshold a, and if ta > c, X = 1, and the air conditioner enters the oil return operation preparation stage;

[0070] S2: The controller judges whether ta is greater than the preset time judgment threshold d, and if ta > d, the air conditioner enters the formal oil return operation stage;

[0071] S3: If F ≥ a, the controller continues to compare the acquired operation frequency F of the compressor with the second judgment threshold b of the preset operation frequency of the compressor, and if F > b, the controller judges whether the value of the mark X of the operation frequency of the compressor less than the first judgment threshold is equal to 1, and if X = 1, the controller counts the duration tb of the operation frequency of the compressor greater than the second judgment threshold b, and judges whether the duration tb of the operation frequency of the compressor greater than the second judgment threshold b reaches the fourth time judgment threshold f, and if tb > f, X = 0, tb = 0, the air conditioner exits the oil return operation preparation stage, and the air conditioner resumes normal operation;

[0072] S4: If a≤F≤b, the controller counts the duration tab when the compressor operating frequency is between the first judgment threshold a and the second judgment threshold b of the compressor operating frequency, and judges whether the duration when the compressor operating frequency is between the first judgment threshold a and the second judgment threshold b of the compressor operating frequency is greater than the preset time threshold e. If tab>e, the air conditioner enters the formal oil return operation stage.

[0073] S5: In S2 and S4, the air conditioner enters the formal oil return operation stage. The controller obtains the information of the indoor ambient temperature Ti and the set temperature Ts, and calculates the temperature difference ΔT between the two. The controller judges whether the calculated result of ΔT is greater than or equal to the preset temperature difference threshold i.

[0074] If △T≥i, the controller sets the compressor's operating frequency F to equal the preset compressor operating frequency h, and the air conditioner operates according to the preset oil return operation program. After the oil return operation program is completed, X=0, ta=0, tab=0, and the air conditioner enters normal operation.

[0075] If △T < i, the controller sets the compressor's operating frequency F to equal the preset compressor operating frequency g, and the air conditioner operates according to the preset oil return operation program. After the oil return operation program is completed, X = 0, ta = 0, tab = 0, and the air conditioner enters normal operation.

[0076] Furthermore, in S3, if tb≤f, the air conditioner operates normally. The controller obtains the compressor operating frequency F and judges whether the compressor operating frequency F is less than or equal to the preset frequency threshold b. If F≤b, tb=0, and the air conditioner operates normally.

[0077] Furthermore, in S3, if F > b, X = 0, and the air conditioner operates normally.

[0078] Furthermore, in S4, if tab≤e, the air conditioner operates normally.

[0079] Furthermore, in S2, ta≤d, the air conditioner is operating normally.

[0080] Furthermore, the time determination thresholds are e > d > c > f, and the compressor operating frequency is h > g.

[0081] Furthermore, in S5, during cooling operation, ΔT = Ti - Ts, and during heating operation, ΔT = Ts - Ti.

[0082] In this embodiment, as Figure 3 The specific steps of the oil return operation control method for an air conditioner are as follows:

[0083] Step S1: In step S1, the air conditioner receives the operation parameter information set by the user, and then enters step S2;

[0084] Step S2: In step S2, the air conditioner operates normally, and then enters step S3;

[0085] Step S3: In step S3, the operation frequency F of the compressor is obtained, and then enters step S4;

[0086] Step S4: In step S4, the obtained operation frequency F of the compressor is compared with the preset first determination threshold a of the operation frequency of the compressor, if F

[0087] Step S5: In step S5, the obtained operation frequency F of the compressor is compared with the preset second determination threshold b of the operation frequency of the compressor, if F

[0088] Step S6: In step S6, it is judged whether the value of the mark X of the operation frequency of the compressor less than the first determination threshold is equal to 1, if X = 1, it enters step S7, otherwise it enters step S2;

[0089] Step S7: In step S7, the duration that the operation frequency of the compressor is greater than the second determination threshold b is counted, and then enters step S8;

[0090] Step S8: In step S8, it is judged whether the duration that the operation frequency of the compressor is greater than the second determination threshold b reaches the fourth time determination threshold f, if tb > f, it enters step S13, otherwise it enters step S9;

[0091] Step S9: In step S9, the air conditioner operates normally, and the operation frequency F of the compressor is obtained, and then enters step S10;

[0092] Step S10: In step S10, it is judged whether the operation frequency F of the compressor is less than or equal to the preset frequency threshold b, if F ≤ b, it enters step S14, otherwise it enters step S7;

[0093] Step S11: In step S11, the duration that the operation frequency of the compressor is between the first determination threshold a and the second determination threshold b of the operation frequency of the compressor is counted, and then enters step S12;

[0094] Step S12: In step S12, it is judged whether the duration that the operation frequency of the compressor is between the first determination threshold a and the second determination threshold b of the operation frequency of the compressor is greater than the preset time threshold e, if tab > e, it enters step S19, otherwise it enters step S2;

[0095] Step S13: In step S13, X=0 is set, and then step S14 is entered;

[0096] Step S14: In step S14, tb=0 is set, and then step S2 is entered;

[0097] Step S15: In step S15, the duration ta of the compressor operating frequency being less than the first determination threshold a is counted, and then step S16 is entered;

[0098] Step S16: In step S16, it is determined whether ta is greater than the preset time determination threshold c, if ta>c, step S17 is entered, otherwise step S2 is entered;

[0099] Step S17: In step S17, X=1 is set, and then step S18 is entered;

[0100] Step S18: In step S18, it is determined whether ta is greater than the preset time determination threshold d, if ta>d, step S19 is entered, otherwise step S2 is entered;

[0101] Step S19: In step S19, the information of the indoor environment temperature Ti and the set temperature Ts is acquired, and AT is calculated, and then step S20 is entered;

[0102] Step S20: In step S20, it is determined whether the calculation result of AT is greater than or equal to the preset temperature difference threshold i, if AT≥i, step S21 is entered, otherwise step S22 is entered;

[0103] Step S21: In step S21, the operating frequency F of the compressor is equal to the preset compressor operating frequency h, and then step S23 is entered;

[0104] Step S22: In step S22, the operating frequency F of the compressor is equal to the preset compressor operating frequency g, and then step S23 is entered;

[0105] Step S23: In step S23, the air conditioner operates according to the preset oil return operating program, and after the oil return operating program is completed, step S24 is entered;

[0106] Step S24: In step S24, X=0, ta=0, and tab=0 are set, and then step S2 is entered;

[0107] Symbol explanation:

[0108] F: compressor operating frequency, Hz;

[0109] a: the first determination threshold of the compressor operating frequency, for example, a is preset to 40 Hz;

[0110] b: second determination threshold of compressor operating frequency, b is preset as 60 Hz;

[0111] ta: duration statistical parameter of compressor operating frequency less than first determination threshold a, min;

[0112] tb: duration statistical parameter of compressor operating frequency greater than second determination threshold b, min;

[0113] tab: duration statistical parameter of compressor operating frequency between first determination threshold a and second determination threshold b, min;

[0114] c: first time determination threshold, c is preset as 20 min; (low frequency operation time is too long)

[0115] d: second time determination threshold, d is preset as 60 min;

[0116] e: third time determination threshold, e is preset as 120 min;

[0117] f: fourth time determination threshold, d is preset as 5 min;

[0118] g: first return oil operation control frequency of compression, g is preset as 60 Hz;

[0119] h: second return oil operation control frequency of compression, h is preset as 70 Hz;

[0120] i: temperature difference determination threshold, i is preset as 1℃;

[0121] Ts: set temperature, ℃;

[0122] Ti: indoor environment temperature, ℃;

[0123] △T: difference between indoor environment temperature Ti and set temperature Ts, △T = Ti - Ts when cooling operation, △T = Ts - Ti when heating operation;

[0124] X: mark of compressor operating frequency less than first determination threshold, X = 1 indicates that compressor operating frequency is less than first determination threshold, X = 0 indicates that compressor operating frequency is not less than first determination threshold;

[0125] In the embodiment, the existing return oil operation control is to limit the low frequency operation time of the compressor. When the compressor operates at low frequency for a period of time, the compressor operating frequency is increased to a certain set frequency for a period of time, the control mode of bringing the compressor lubricating oil back to the inside of the compressor will cause excessive refrigerating capacity or heating capacity output, cause the fluctuation of indoor environment temperature, and affect the comfort in the use process of the air conditioner. The control logic can obtain the following control effects.

[0126] 1. When the compressor frequency runs for a certain length of time at a frequency lower than a preset frequency, the compressor enters the oil return operation preparation stage;

[0127] 2. When the compressor frequency reaches a preset threshold and runs for a certain length of time in the oil return operation preparation stage, the compressor exits the oil return operation preparation stage;

[0128] 3. When the duration of the oil return operation preparation stage reaches a preset length of time, the compressor enters the formal oil return operation;

[0129] 4. When the compressor frequency runs for a certain length of time at a relatively low frequency, the compressor enters the formal oil return operation;

[0130] 5. Before entering the oil return operation, the temperature difference between the indoor environment temperature and the set temperature set by the user is determined. If the temperature difference is less than a preset temperature difference threshold, the compressor operates according to the first oil return operation mode, otherwise, the compressor operates according to the second oil return operation mode.

[0131] In the oil return operation preparation stage, if the operating condition of the compressor oil return operation appears (such as the compressor operating frequency is higher than b and the time lasts for f), the oil return operation preparation stage is exited, the number of intentional entering the oil return operation is reduced, and the energy efficiency is improved. This scheme can also formulate different operating limit times (such as preset time determination thresholds d, e) for the compressor in the above three different frequency bands. In addition, this scheme can formulate different compressor oil return operation strategies for different indoor temperature differences △T. The compressor oil return operation frequency when △T is small is less than the compressor oil return operation frequency when △T is large, which avoids the situation that the indoor temperature is too low (in cooling operation) or the indoor temperature is too high (in heating operation) due to the excessive output of cold or heat by the air conditioner when the temperature difference between the indoor temperature and the set temperature is too small, thereby affecting the indoor thermal comfort.

[0132] In the description of the present specification, the description of the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the described specific features, structures, materials or characteristics can be combined in any one or more embodiments or examples in a suitable manner.

[0133] Although the embodiments of the present application have been shown and described above, it is understood that the above-described embodiments are exemplary and are not to be construed as limiting the present application, and that changes, modifications, substitutions and variations can be made by those skilled in the art without departing from the spirit and scope of the present application.

Claims

1. A method for controlling the return oil operation of an air conditioner, applied to an air conditioner (1), the air conditioner (1) comprising a controller, an indoor unit (10) and an outdoor unit (20); characterized in that: The indoor unit (10) includes an indoor heat exchanger (101), an indoor ambient temperature sensor (102), an indoor heat exchanger temperature sensor (103), an indoor fan (104), an indoor control mechanism (105), and an air supply direction adjustment mechanism; The outdoor unit (20) includes a compressor (201), a four-way reversing valve (202), an outdoor heat exchanger (203), an outdoor fan (204), a throttling mechanism (205) for controlling flow, and an outdoor control mechanism (206); the indoor heat exchanger (101) and the outdoor heat exchanger (203) form a circuit through a first refrigerant connection pipe (30) and a second refrigerant connection pipe (40), the compressor (201) and the throttling mechanism (205) are arranged in the above circuit, and the four-way reversing valve (202) is used to switch the valve port so that the air conditioner has a cooling mode and a heating mode; the controller includes an indoor control mechanism (105) and an outdoor control mechanism (206); the control method steps are as follows: S1: The air conditioner receives the operating parameters set by the user, and the controller obtains the compressor operating frequency F; the obtained compressor operating frequency F is compared with the preset compressor operating frequency first judgment threshold a. If F < a, the controller counts the duration ta during which the compressor operating frequency is less than the first judgment threshold a. If ta > c, let X = 1, and the air conditioner enters the oil return operation preparation stage. S2: The controller judges whether ta is greater than the preset time threshold d. If ta>d, the air conditioner enters the formal oil return operation stage. S3: If F≥a, the controller continues to compare the obtained compressor operating frequency F with the preset second judgment threshold b of the compressor operating frequency. If F>b, the controller judges whether the value of the marker X for the compressor operating frequency being less than the first judgment threshold is equal to 1. If X=1, the controller counts the duration tb of the compressor operating frequency being greater than the second judgment threshold b and judges whether the duration tb of the compressor operating frequency being greater than the second judgment threshold b reaches the fourth time judgment threshold f. If tb>f, X=0, tb=0, the air conditioner exits the oil return operation preparation stage, and the air conditioner resumes normal operation. S4: If a≤F≤b, the controller counts the duration tab when the compressor operating frequency is between the first judgment threshold a and the second judgment threshold b of the compressor operating frequency, and judges whether the duration when the compressor operating frequency is between the first judgment threshold a and the second judgment threshold b of the compressor operating frequency is greater than the preset time threshold e. If tab>e, the air conditioner enters the formal oil return operation stage. S5: In S2 and S4, the air conditioner enters the formal oil return operation stage. The controller obtains the information of the indoor ambient temperature Ti and the set temperature Ts, and calculates the temperature difference ΔT between the two. The controller judges whether the calculated result of ΔT is greater than or equal to the preset temperature difference threshold i. If △T≥i, the controller sets the compressor's operating frequency F to equal the preset compressor operating frequency h, and the air conditioner operates according to the preset oil return operation program. After the oil return operation program is completed, X=0, ta=0, tab=0, and the air conditioner enters normal operation. If △T < i, the controller sets the compressor's operating frequency F to equal the preset compressor operating frequency g, and the air conditioner operates according to the preset oil return operation program. After the oil return operation program is completed, X = 0, ta = 0, tab = 0, and the air conditioner enters normal operation.

2. The method for controlling the oil return operation of an air conditioner according to claim 1, characterized in that: In S3, if tb≤f, the air conditioner operates normally. The controller obtains the compressor operating frequency F and judges whether the compressor operating frequency F is less than or equal to the preset frequency threshold b. If F≤b, tb=0, and the air conditioner operates normally.

3. The method for controlling the oil return operation of an air conditioner according to claim 1, characterized in that: In S3, if F > b, X = 0, the air conditioner operates normally.

4. The method for controlling the oil return operation of an air conditioner according to claim 1, characterized in that: In S4, if tab≤e, the air conditioner operates normally.

5. The method for controlling the oil return operation of an air conditioner according to claim 1, characterized in that: In S2, ta≤d, the air conditioner is operating normally.

6. The method for controlling the oil return operation of an air conditioner according to claim 1, characterized in that: The time threshold is e > d > c > f, and the compressor operating frequency is h > g.

7. The method for controlling the oil return operation of an air conditioner according to claim 1, characterized in that: In S5, when operating in cooling mode, ΔT = Ti - Ts, and when operating in heating mode, ΔT = Ts - Ti.

8. The method for controlling the oil return operation of an air conditioner according to claim 1, characterized in that: The indoor control mechanism (105) includes: The user information receiving module (1051) is adapted to receive the air conditioner operation status setting information set by the user; The first operation information acquisition module (1052) is adapted to acquire the operation information of each device in the indoor unit (10) and the information received by the user information receiving module (1051); The time acquisition / statistics module (1053) is suitable for acquiring the current date and time and calculating the duration of the compressor's operation at various frequencies. The first information sending / receiving module (1054) is suitable for communicating with the outdoor control mechanism; The first information storage module (1055) is suitable for storing user setting parameter information received by the air conditioner and storing various operating states and operating time information during the operation of the air conditioner. The operating status judgment module (1056) is suitable for determining whether the air conditioner needs to enter or exit the oil return operation based on the current operating status of the air conditioner and the operating time in each status.

9. The method for controlling the oil return operation of an air conditioner according to claim 8, characterized in that: The outdoor control mechanism (206) includes: Second information storage module (2061); The second information sending / receiving module (2064) is adapted to communicate with the indoor control mechanism (105); The operation information acquisition module (2062) is suitable for acquiring the operation information of each component in the outdoor unit (20) and the information received by the information sending / receiving module (2064); The compressor operating frequency control (2063) is suitable for controlling the operating frequency of the compressor (201).

10. An air conditioner, characterized in that: The method for controlling the oil return operation of an air conditioner as described in any one of claims 1 to 9 above.

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