Auxiliary oil return control method for air conditioning system, controller, system and medium

Abstract

The invention discloses an auxiliary oil return control method for an air conditioning system, a controller, a system and a medium, and relates to the technical field of oil return control. The method comprises the steps that under the condition that a compressor is started in a heating mode, when the outdoor environment temperature is smaller than the indoor environment temperature and the exhaust temperature of an exhaust port of the compressor is smaller than a first temperature threshold value, the air conditioning system is controlled to enter a first working mode, curve fitting is conducted on a preset quadratic function curve according to the multiple sets of exhaust temperature detection values obtained through detection and the corresponding first operation time, and an objective function is obtained; controlling the air conditioning system to enter a second working mode after the first working mode is finished; in the second working mode, when the exhaust temperature is larger than or equal to a second temperature threshold value, the air conditioning system is controlled to enter a third working mode; and in the third working mode, when the exhaust temperature is smaller than or equal to a third temperature threshold value, the air conditioning system is controlled to enter a fourth working mode. Auxiliary oil return can be achieved under the condition that pipeline devices do not need to be added, and oil shortage abrasion of the compressor is reduced.

Description

Technical Field

[0001] The present application relates to the technical field of oil return control, and in particular to an auxiliary oil return control method, a controller, a system, and a medium for an air conditioning system. Background Art

[0002] In a multi-split air conditioning system, when some indoor units are not turned on or are in a low-temperature static state, liquid refrigerant deposits at the bottom of the compressor. In most systems during heating startup, especially when starting with accumulated liquid at low temperature and static state, at the initial stage of startup, as the compressor frequency increases or with the passage of time, it is gradually emptied. Inevitably, there is a situation where the refrigerating oil is discharged from the compressor along with the refrigerant. Therefore, most compressors allow a transitional oil shortage time of about 1 - 5 minutes at the initial stage of startup.

[0003] However, long-term oil shortage operation of the compressor will cause wear. In order to ensure that the oil shortage time of the compressor is controlled within the allowable time, the existing conventional method is to add an oil separator at the exhaust port to directly return the discharged refrigerating oil to the compressor or add a gas-liquid separator at the suction port to store the migrated refrigerant outside, reducing the amount of refrigerant deposited in the compressor, thereby reducing the amount of refrigerating oil discharged during startup. Among them, the purpose of adding a gas-liquid separator is to store the excess liquid refrigerant in the gas-liquid separator to prevent the liquid refrigerant from being directly discharged from the compressor and taking away the refrigerating oil; the purpose of adding an oil separator is that when the refrigerating oil is discharged from the compressor, the oil separator separates the refrigerant and the refrigerating oil at the exhaust port, the refrigerant normally enters the heat exchanger for circulation, and the refrigerating oil directly flows back to the compressor suction port through the oil return branch. Although these two schemes are relatively mature and reliable, they also have the following disadvantages: (1) The increase in pipeline components causes an increase in cost, especially for small-capacity units with high cost pressure; (2) The increase in pipeline components makes pipeline design difficult, especially when there are many expansion valve components in a multi-group pipe type multi-split unit and there is less remaining space inside the housing, it is difficult to place large-volume containers such as gas-liquid separators and oil separators; (3) It increases the energy consumption of the unit. The oil separator needs to design a high-low pressure bypass oil return branch. When the compressor frequency is low and the oil discharge is small, when the oil return branch cannot be filled with refrigerating oil, the compressed refrigerant will directly bypass back to the compressor suction port through this branch, causing ineffective compression and increasing energy consumption; while the gas-liquid separator, as a large-capacity container, will cause an increase in system resistance and an increase in compression power. Therefore, how to assist oil return without increasing pipeline components and reduce the oil shortage wear of the compressor is an urgent problem to be solved. Summary of the Invention

[0004] This application aims to solve at least one of the technical problems existing in the prior art. To this end, this application proposes an auxiliary oil return control method, a controller, a system, and a medium for an air-conditioning system, which can assist in oil return without adding pipeline components, reduce costs and the difficulty of pipeline design, while reducing the oil shortage wear of the compressor and ensuring the stable operation of the compressor.

[0005] In a first aspect, an embodiment of this application provides an auxiliary oil return control method for an air-conditioning system, including:

[0006] When the outdoor ambient temperature obtained is less than the indoor ambient temperature obtained and the exhaust temperature at the compressor exhaust port is less than a first temperature threshold during the heating start of the compressor, control the air-conditioning system to enter a first working mode; the first temperature threshold is obtained by adding the outdoor ambient temperature and a preset first temperature difference;

[0007] In the first working mode, perform curve fitting processing on a preset quadratic function curve according to multiple groups of detected exhaust temperature detection values and corresponding first running times to obtain an objective function; the first running time is the duration elapsed from the start time to the detection time; the objective function is used to represent the corresponding relationship between the exhaust temperature T and the running time t of the compressor;

[0008] After the first working mode ends, control the air-conditioning system to enter a second working mode;

[0009] In the second working mode, when the exhaust temperature detected in real time is greater than or equal to a second temperature threshold, control the air-conditioning system to enter a third working mode; wherein, the second temperature threshold is obtained by adding a first exhaust temperature calculation value calculated through the objective function and a preset second temperature difference;

[0010] In the third working mode, when the exhaust temperature detected in real time is less than or equal to a third temperature threshold, control the air-conditioning system to enter a fourth working mode; wherein, the third temperature threshold is obtained by adding a second exhaust temperature calculation value calculated through the objective function and a preset third temperature difference.

[0011] According to some embodiments of this application, the controlling the air-conditioning system to enter the first working mode includes:

[0012] Control the compressor to operate at a first preset frequency for a preset period.

[0013] According to some embodiments of this application, the performing curve fitting processing on a preset quadratic function curve according to multiple groups of detected exhaust temperature detection values and corresponding first running times in the first working mode to obtain an objective function includes:

[0014] In the first operating mode, obtain a preset quadratic function curve, multiple sets of exhaust gas temperature detection values, and the corresponding first operating time;

[0015] Substitute the multiple sets of exhaust gas temperature detection values and the corresponding first operating time into the preset quadratic function curve to obtain the value of the parameter information to be solved in the preset quadratic function curve;

[0016] Determine the objective function according to the value of the parameter information to be solved.

[0017] According to some embodiments of the present application, the expression of the objective function is: The parameter information to be solved includes: parameter a, parameter h, and parameter k. Among them, parameter a is used to characterize the opening size of the objective function, parameter h is used to characterize the horizontal translation amount of the objective function; parameter k is used to characterize the vertical translation amount of the objective function.

[0018] According to some embodiments of the present application, the controlling the air-conditioning system to enter the second operating mode includes:

[0019] Obtain a second preset frequency; the second preset frequency is greater than the first preset frequency;

[0020] Control the compressor to operate at the second preset frequency.

[0021] According to some embodiments of the present application, the when the exhaust gas temperature detected in real time is greater than or equal to the second temperature threshold, controlling the air-conditioning system to enter the third operating mode includes:

[0022] Obtain the exhaust gas temperature detected in real time and the corresponding second operating time; the second operating time is the duration elapsed from the start time to the detection time;

[0023] Substitute the second operating time into the objective function for calculation to obtain a first exhaust gas temperature calculation value;

[0024] Add the first exhaust gas temperature calculation value to the preset second temperature difference to obtain the second temperature threshold;

[0025] When the exhaust gas temperature detected in real time is greater than or equal to the second temperature threshold, control the compressor to resume operating at the first preset frequency, and control the opening degree of each electronic expansion valve to increase by a preset number of steps based on the current initial opening degree.

[0026] According to some embodiments of the present application, the when the exhaust gas temperature detected in real time is less than or equal to the third temperature threshold, controlling the air-conditioning system to enter the fourth operating mode includes:

[0027] Obtain the detected exhaust temperature in real time and the corresponding third running time; the third running time is the duration elapsed from the start time to the detection time;

[0028] Substitute the third running time into the objective function for calculation to obtain a second calculated exhaust temperature value;

[0029] Add the second calculated exhaust temperature value to the preset third temperature difference to obtain the third temperature threshold;

[0030] When the exhaust temperature detected in real time is less than or equal to the third temperature threshold, control the opening degrees of the respective electronic expansion valves to return to the initial opening degrees, control the compressor to operate at a third preset frequency, and control the respective electronic expansion valves to return to the preset opening degrees on the basis of the initial opening degrees.

[0031] In a second aspect, an embodiment of the present application provides a controller, including at least one processor and a memory for communicatively connecting with the at least one processor; the memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor to enable the at least one processor to execute the auxiliary oil return control method for an air-conditioning system according to any one of the embodiments in the first aspect.

[0032] In a third aspect, an embodiment of the present application provides an air-conditioning system, including the controller according to the embodiment in the second aspect.

[0033] In a fourth aspect, an embodiment of the present application provides a computer-readable storage medium, and the computer-readable storage medium stores computer-executable instructions for causing a computer to execute the auxiliary oil return control method for an air-conditioning system according to any one of the embodiments in the first aspect.

[0034] Embodiments of the present application include: When the air-conditioning system is operating and the compressor starts heating, first, when the obtained outdoor ambient temperature is less than the obtained indoor ambient temperature and the exhaust temperature at the compressor exhaust port is less than the first temperature threshold, the air-conditioning system is controlled to enter the first working mode; the first temperature threshold is obtained by adding the outdoor ambient temperature and a preset first temperature difference; secondly, in the first working mode, curve fitting processing is performed on a preset quadratic function curve according to multiple groups of detected exhaust temperature detection values and corresponding first running times to obtain an objective function; the first running time is the duration elapsed from the start time to the detection time; the objective function is used to represent the corresponding relationship between the exhaust temperature T and the running time t of the compressor; then, after the first working mode ends, the air-conditioning system is controlled to enter the second working mode; then, in the second working mode, when the exhaust temperature detected in real time is greater than or equal to the second temperature threshold, the air-conditioning system is controlled to enter the third working mode; wherein, the second temperature threshold is obtained by adding a first exhaust temperature calculated value obtained by calculating through the objective function and a preset second temperature difference; finally, in the third working mode, when the exhaust temperature detected in real time is less than or equal to the third temperature threshold, the air-conditioning system is controlled to enter the fourth working mode; wherein, the third temperature threshold is obtained by adding a second exhaust temperature calculated value obtained by calculating through the objective function and a preset third temperature difference; by switching different working modes, when the air-conditioning system is neither equipped with a gas-liquid separator nor an oil separator, during liquid accumulation and liquid-carrying start-up, the liquid refrigerant deposited inside the compressor can be quickly emptied, and the refrigeration oil emptied together with the refrigerant can quickly complete the system cycle and return to the compressor, reducing the oil shortage wear of the compressor and realizing the normal and stable operation of the compressor. That is to say, the embodiments of the present application can assist in oil return without adding pipeline components, reduce costs and pipeline design difficulties, while reducing the oil shortage wear of the compressor and ensuring the stable operation of the compressor. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 is a schematic electrical connection diagram of an air-conditioning system provided by an embodiment of the present application;

[0036] Figure 2 is a schematic system structure diagram of an air-conditioning system provided by an embodiment of the present application;

[0037] Figure 3 is a schematic flow diagram of an auxiliary oil return control method for an air-conditioning system provided by an embodiment of the present application;

[0038] Figure 4 is a schematic diagram of an objective function provided by an embodiment of the present application;

[0039] Figure 5It is a schematic diagram of the change curve of the exhaust temperature over time during the startup process of the compressor when applying the auxiliary oil return control method provided by an embodiment of the present application;

[0040] Figure 6 It is a schematic diagram of the change curve of the exhaust temperature over time during the startup process of the compressor when not applying the auxiliary oil return control method provided by an embodiment of the present application;

[0041] Figure 7 It is a schematic diagram of the overall flow of the auxiliary oil return control method for the air conditioning system provided by an embodiment of the present application;

[0042] Figure 8 It is a schematic diagram of the hardware structure of the electronic device provided by an embodiment of the present application. Detailed implementation manners

[0043] In order to make the objectives, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the accompanying drawings and embodiments.

[0044] It should be understood that in the description of the present application, the directional descriptions such as up, down, front, back, left, right, etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation to the present application.

[0045] It should be noted that although the logical order is shown in the flowchart in the description of the present application, in some cases, the steps shown or described can be executed in a sequence different from that in the flowchart. In the description of the present application, the meaning of several is one or more, and the meaning of multiple is two or more. The descriptions of "first" and "second" are only for the purpose of distinguishing technical features, and should not be construed as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features or the sequence of the indicated technical features.

[0046] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which the present application belongs. The terms used herein are only for the purpose of describing the embodiments of the present application and are not intended to limit the present application.

[0047] The present application provides an auxiliary oil return control method for an air conditioning system, a controller, an air conditioning system, and a computer-readable storage medium, relating to the technical field of oil return control. The method includes: when the compressor starts heating, if the outdoor ambient temperature is less than the indoor ambient temperature and the exhaust temperature at the compressor exhaust port is less than a first temperature threshold, controlling the air conditioning system to enter a first working mode, and curve fitting a preset quadratic function curve according to multiple groups of detected exhaust temperature detection values and corresponding first running times to obtain an objective function; after the first working mode ends, controlling the air conditioning system to enter a second working mode; when the exhaust temperature is greater than or equal to a second temperature threshold in the second working mode, controlling the air conditioning system to enter a third working mode; when the exhaust temperature is less than or equal to a third temperature threshold in the third working mode, controlling the air conditioning system to enter a fourth working mode. It can assist in oil return without adding pipeline components, reduce oil shortage wear of the compressor.

[0048] The following further elaborates on the embodiments of the present application in conjunction with the accompanying drawings.

[0049] In the first aspect, as Figure 1 shown, the air conditioning system 100 includes: a controller 101, a compressor 102 electrically connected to the controller 101, an exhaust temperature sensor 103, an ambient temperature sensor 108, and an electronic expansion valve 114. The air conditioning system 100 of the embodiments of the present application can be a multi-connected air conditioning system. Specifically, as Figure 2 shown, the air conditioning system 100 includes but is not limited to: a compressor 102, an exhaust temperature sensor 103 disposed at the exhaust port of the compressor 102, a muffler 104, a four-way valve 105, a condenser 106, an outer pipe temperature sensor 107 and an ambient temperature sensor 108 disposed on the condenser 106, an outer fan 109, a plurality of first pipeline branch units 110, and a plurality of indoor units 111; one end of each first pipeline branch unit 110 is connected to the outer fan 109 through a first filter 112, and the other end of each first pipeline branch unit 110 is connected to one end of an indoor unit 111; the other end of the indoor unit 111 is connected to one end of the four-way valve 105 through a second pipeline branch unit 113; an electronic expansion valve 114, a second filter 115, and an inlet 116 are sequentially connected on each first pipeline branch unit 110; an outlet 117 is disposed on each second pipeline branch unit 113.

[0050] In the air conditioning system 100, through the coordinated cooperation of the controller 101, the exhaust temperature sensor 103, the ambient temperature sensor 108, and the electronic expansion valve 114, the controller 101 executes the auxiliary oil return control method for the air conditioning system provided by the embodiments of the present application, which can assist in oil return without adding pipeline components, reduce costs and the difficulty of pipeline design, while reducing oil shortage wear of the compressor and ensuring the stable operation of the compressor.

[0051] Those skilled in the art can understand that the system structure shown in the figures does not constitute a limitation on the embodiments of the present application. It may include more or fewer components than shown in the figures, or combine certain components, or have different component arrangements.

[0052] The system embodiments described above are merely illustrative. The units described as separate components may or may not be physically separated, that is, they may be located in one place, or distributed to multiple network units. Some or all of the modules can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0053] Those skilled in the art can understand that the system architecture and application scenarios described in the embodiments of the present application are for more clearly explaining the technical solutions of the embodiments of the present application, and do not constitute a limitation on the technical solutions provided by the embodiments of the present application. As those skilled in the art know, with the evolution of the system architecture and the emergence of new application scenarios, the technical solutions provided by the embodiments of the present application are equally applicable to similar technical problems.

[0054] Based on the above system structure, various embodiments of the auxiliary oil return control method for the air conditioning system of the present application are proposed below.

[0055] In a first aspect, as Figure 3 shown, the auxiliary oil return control method for the air conditioning system can be applied to the controller of the air conditioning system as Figure 1 shown. The auxiliary oil return control method for the air conditioning system may include, but is not limited to, steps S110 to S150.

[0056] Step S110: When the air conditioner starts heating, when the obtained outdoor ambient temperature is less than the obtained indoor ambient temperature and the exhaust temperature at the compressor exhaust port is less than the first temperature threshold, control the air conditioning system to enter the first working mode; the first temperature threshold is obtained by adding the outdoor ambient temperature and a preset first temperature difference.

[0057] Step S120: In the first working mode, perform curve fitting on a preset quadratic function curve according to the detected multiple groups of exhaust temperature detection values and the corresponding first running time to obtain an objective function; the first running time is the duration from the start time to the detection time; the objective function is used to characterize the corresponding relationship between the exhaust temperature T and the running time t of the compressor.

[0058] Step S130: After the first working mode ends, control the air conditioning system to enter the second working mode.

[0059] Step S140: In the second working mode, when the exhaust temperature detected in real time is greater than or equal to the second temperature threshold, control the air-conditioning system to enter the third working mode; wherein, the second temperature threshold is obtained by adding the first exhaust temperature calculated value obtained through the objective function and a preset second temperature difference.

[0060] Step S150: In the third working mode, when the exhaust temperature detected in real time is less than or equal to the third temperature threshold, control the air-conditioning system to enter the fourth working mode; wherein, the third temperature threshold is obtained by adding the second exhaust temperature calculated value obtained through the objective function and a preset third temperature difference.

[0061] Specifically, in step S110, the outdoor ambient temperature is detected by an ambient temperature sensor. The indoor ambient temperature is detected by a temperature sensor. The exhaust temperature at the compressor exhaust port is detected by an exhaust temperature sensor provided at the compressor exhaust port.

[0062] Specifically, the preset first temperature difference is preset, and the value of the preset first temperature difference is 5 degrees Celsius. The starting moment is Figure 5 the 0 moment shown.

[0063] Further illustrate step S110; According to some embodiments of the present application, controlling the air-conditioning system to enter the first working mode includes: controlling the compressor to operate at a first preset frequency for a preset period.

[0064] Through step S110, after the heating compressor starts, the oil return ends, and the defrosting ends, in the case of heating start, when T 室外环境 < T 室内环境 , that is, the outdoor ambient temperature is less than the indoor ambient temperature (this condition needs to be judged only in the starting case), and T 排气 < T 室外环境 + 5°C, it means that the compressor has been static at a relatively low temperature compared to the indoor environment for a long time, or there is more liquid refrigerant flowing back to the compressor during the oil return and defrosting processes, resulting in a lower exhaust temperature. Then control the compressor to operate at a first preset frequency for a preset period.

[0065] It should be emphasized that the embodiments of the present application utilize the characteristic that the compressor has a transitional oil shortage time, and make the refrigerating oil flow back into the compressor during the transitional oil shortage time, so as to reduce the oil shortage wear of the compressor and protect the compressor without adding other components such as a gas-liquid separator and an oil separator.

[0066] Through steps S110 to S150, when the air conditioning system is operating and the compressor starts heating, first, when the obtained outdoor ambient temperature is less than the obtained indoor ambient temperature and the exhaust temperature at the compressor outlet is less than the first temperature threshold, the air conditioning system is controlled to enter the first working mode; the first temperature threshold is obtained by adding the outdoor ambient temperature and a preset first temperature difference; secondly, in the first working mode, curve fitting processing is performed on a preset quadratic function curve according to multiple groups of detected exhaust temperature detection values and corresponding first running times to obtain an objective function; the first running time is the duration from the start time to the detection time; the objective function is used to represent the corresponding relationship between the exhaust temperature T and the running time t of the compressor; then, after the first working mode ends, the air conditioning system is controlled to enter the second working mode; then, in the second working mode, when the detected exhaust temperature is greater than or equal to the second temperature threshold, the air conditioning system is controlled to enter the third working mode; wherein, the second temperature threshold is obtained by adding a first exhaust temperature calculation value obtained by calculating through the objective function and a preset second temperature difference; finally, in the third working mode, when the detected exhaust temperature is less than or equal to the third temperature threshold, the air conditioning system is controlled to enter the fourth working mode; wherein, the third temperature threshold is obtained by adding a second exhaust temperature calculation value obtained by calculating through the objective function and a preset third temperature difference; by switching different working modes, when the air conditioning system is neither equipped with a gas-liquid separator nor an oil separator, during liquid accumulation and liquid-carrying start-up, the liquid refrigerant deposited inside the compressor is quickly emptied, and the refrigeration oil emptied together with the refrigerant quickly completes the system cycle and returns to the compressor, reducing the oil shortage wear of the compressor and realizing the normal and stable operation of the compressor. That is to say, the embodiments of the present application can assist in oil return without adding pipeline components, reduce costs and the difficulty of pipeline design, while reducing the oil shortage wear of the compressor and ensuring the stable operation of the compressor.

[0067] According to some embodiments of the present application, step S120 is further described. Among them, in the first working mode, curve fitting processing is performed on a preset quadratic function curve according to multiple groups of detected exhaust temperature detection values and corresponding first running times to obtain an objective function, including but not limited to steps S121 to S123.

[0068] Step S121: In the first working mode, obtain a preset quadratic function curve, multiple groups of exhaust temperature detection values, and corresponding first running times.

[0069] Step S122: Substitute multiple groups of exhaust temperature detection values and corresponding first running times into the preset quadratic function curve to obtain the values of the parameter information to be solved in the preset quadratic function curve.

[0070] Step S123: Determine the objective function according to the value of the parameter information to be solved.

[0071] Specifically, step S121 includes: in the first working mode, that is, within the preset period of running at the first preset frequency, obtain the exhaust gas temperature detection value corresponding to the detection moment, and subtract the start moment of the compressor from the detection moment to obtain the corresponding first running time; after multiple detections and acquisitions, obtain multiple groups of exhaust gas temperature detection values and the corresponding first running time. This lays a data foundation for curve fitting processing based on a preset quadratic function curve.

[0072] Specifically, further illustrate step S122. Within the preset period of running at the first preset frequency, at this time, the oil storage amount of the compressor is still in a relatively healthy state. Taking the running time t of the compressor as the ordinate and the exhaust gas temperature T as the abscissa, construct a preset quadratic function curve: t = a(T - k) 2 + h; where the value of T is greater than or equal to the directrix, that is, T ≥ h - (1 / 4a). The parameter information to be solved includes: parameter a, parameter h, and parameter k.

[0073] Give an example to illustrate step S122. Arbitrarily take the exhaust gas temperature detection values T 排气1 、T 排气2 、T 排气3 corresponding to the moments t1, t2, and t3 within the preset period of running at the first preset frequency; substitute these three groups of exhaust gas temperature detection values and the corresponding first running time into the preset quadratic function curve for fitting to obtain the objective function corresponding to the exhaust gas temperature T and the running time t of the compressor when the oil level is normal.

[0074] According to some embodiments of the present application, the expression of the objective function is: The parameter information to be solved includes: parameter a, parameter h, and parameter k. Among them, parameter a is used to characterize the opening size of the objective function, parameter h is used to characterize the horizontal translation amount of the objective function; parameter k is used to characterize the vertical translation amount of the objective function. Among them, the obtained objective function is a function curve with an opening to the right showing the change of T with t, as Figure 4 shown.

[0075] Through steps S121 to S123, within the preset period of running at the first preset frequency, perform curve fitting processing to obtain the objective function for characterizing the corresponding relationship between the exhaust gas temperature T and the running time t of the compressor, which lays a foundation for subsequent calculation of the exhaust gas temperature calculation value.

[0076] According to some embodiments of the present application, further illustrate step S130. Among them, controlling the air conditioning system to enter the second working mode includes, but is not limited to, steps S131 to S132.

[0077] Step S131: Obtain a second preset frequency; the second preset frequency is greater than the first preset frequency.

[0078] Step S132: Control the compressor to operate at the second preset frequency.

[0079] To further explain step S131, it should be noted that to ensure sufficient oil supply, at the initial stage of startup, most compressors themselves have the requirement to operate at a certain frequency range for at least a period of time to preheat the refrigeration oil at low frequency and reduce its viscosity. Generally, the recommended frequency range is 30 Hz to 50 Hz, and the preset period is more than 30 s, which specifically depends on the compressor model. Therefore, the value range of the first preset frequency is: 30 Hz to 50 Hz. The second preset frequency (heating oil return frequency) used during heating oil return is obtained through actual measurement based on the matching of the compressor and the system. At the second preset frequency, the pressure difference generated by the air-conditioning system can push the refrigeration oil back into the compressor. There is no direct relationship between the first preset frequency and the second preset frequency, but generally, the first preset frequency is less than the second preset frequency. Based on this, the values of the first preset frequency and the second preset frequency in the first embodiment of this application are not specifically limited.

[0080] To further explain step S132, specifically, when the operating time of the compressor reaches the preset period, control the frequency of the compressor to rise to the second preset frequency. By increasing the operating frequency of the compressor, the liquid refrigerant deposited inside the compressor can be quickly emptied. At this time, the refrigeration oil will also be discharged from the compressor along with the refrigerant, and after complete emptying, the compressor will lack lubrication, resulting in a sudden increase in the exhaust temperature.

[0081] Through steps S131 to S132, after the end of the first working mode, the compressor in the air-conditioning system enters the second working mode, and by increasing the operating frequency of the compressor, the liquid refrigerant deposited inside the compressor can be quickly emptied.

[0082] According to some embodiments of the present application, to further explain step S140, wherein when the real-time detected exhaust temperature is greater than or equal to the second temperature threshold, control the air-conditioning system to enter the third working mode, including but not limited to steps S141 to S144.

[0083] Step S141: Obtain the real-time detected exhaust temperature and the corresponding second operating time; the second operating time is the duration elapsed from the start time to the detection time.

[0084] Step S142: Substitute the second operating time into the objective function for calculation to obtain the first exhaust temperature calculation value.

[0085] Step S143: Add the first exhaust temperature calculation value to the preset second temperature difference to obtain the second temperature threshold.

[0086] Step S144: When the exhaust temperature detected in real time is greater than or equal to the second temperature threshold, control the compressor to resume operation at the first preset frequency, and control the opening degrees of the respective electronic expansion valves to increase by a preset number of steps based on the current initial opening degrees.

[0087] It can be understood that through step S132, the frequency of the compressor is increased to the second preset frequency, so as to quickly evacuate the liquid refrigerant deposited inside the compressor. At this time, the refrigeration oil will also be discharged from the compressor together with the refrigerant. After the liquid refrigerant is completely evacuated, the compressor lacks lubrication, resulting in a sudden increase in the exhaust temperature. There is a fixed second temperature difference △T1 between the temperature at this mutation point (i.e., the second temperature threshold) and the exhaust temperature in the actual normal operating state (this second temperature difference △T1 can be obtained through actual measurement). That is, when the actual exhaust temperature T is greater than or equal to the sum of the first exhaust temperature calculated value and the second temperature threshold, it represents that the liquid refrigerant has been completely evacuated.

[0088] Specifically, the process of determining the second temperature threshold is as follows: Obtain the exhaust temperature detected in real time and the corresponding second running time through step S141; substitute the second running time into the objective function for calculation through step S142 to obtain the first exhaust temperature calculated value; add the first exhaust temperature calculated value and the preset second temperature difference through step S143 to obtain the second temperature threshold; obtaining the second temperature threshold provides a reliable reference for judging whether the liquid refrigerant is completely evacuated.

[0089] It can be understood that as the second running time changes, the first exhaust temperature calculated value calculated in real time is also different, and thus the obtained second temperature threshold is also different. Dynamically determining the second temperature threshold makes the judgment on whether the liquid refrigerant is completely evacuated more accurate.

[0090] Specifically, when the exhaust temperature detected in real time is greater than or equal to the second temperature threshold, it is determined that the liquid refrigerant has been completely evacuated. Then, control the operating frequency of the compressor to resume to the first preset frequency, and control the opening degrees of the respective electronic expansion valves to increase by a preset number of steps based on the current initial opening degrees. By increasing the opening degrees of the electronic expansion valves, the resistance for the refrigeration oil to return to the compressor is reduced, and the time taken for the refrigeration oil to return to the compressor again is shortened, so as to meet the requirement of the compressor running with short-term lack of oil at the initial stage of startup.

[0091] It should be noted that the specific value of the preset number of steps is obtained through actual measurement, and the present application does not make specific limitations on the value of the preset number of steps.

[0092] Through steps S141 to S144, the second temperature threshold obtained by real-time calculation is compared with the exhaust temperature detected in real time to determine whether the liquid refrigerant is completely emptied; when the liquid refrigerant is completely emptied, the compressor is controlled to resume operation at the first preset frequency, and at the same time, the opening degrees of each electronic expansion valve are increased to shorten the time taken for the refrigeration oil to return to the compressor, so as to meet the requirement of the compressor for short-time oil-deficient operation at the initial stage of startup.

[0093] According to some embodiments of the present application, step S150 is further described. Among them, when the exhaust temperature detected in real time is less than or equal to the third temperature threshold, the air-conditioning system is controlled to enter the fourth working mode, including but not limited to steps S151 to S154.

[0094] Step S151: Obtain the exhaust temperature detected in real time and the corresponding third running time; the third running time is the duration elapsed from the start time to the detection time.

[0095] Step S152: Substitute the third running time into the objective function for calculation to obtain the calculated value of the second exhaust temperature.

[0096] Step S153: Add the calculated value of the second exhaust temperature to the preset third temperature difference to obtain the third temperature threshold.

[0097] Step S154: When the exhaust temperature detected in real time is less than or equal to the third temperature threshold, control the opening degrees of each electronic expansion valve to return to the initial opening degrees, control the compressor to operate at the third preset frequency, and control each electronic expansion valve to return to the preset opening degrees on the basis of the initial opening degrees.

[0098] It can be understood that through step S144, the operating frequency of the compressor is controlled to resume to the first preset frequency, and the opening degrees of each electronic expansion valve are controlled to increase by a preset number of steps based on the current initial opening degrees. By increasing the opening degrees of the electronic expansion valves, the resistance for the refrigeration oil to return to the compressor is reduced, and the time taken for the refrigeration oil to return to the compressor again is shortened, so as to meet the requirement of the compressor for short-time oil-deficient operation at the initial stage of startup. As the compressor motor is lubricated again, the exhaust temperature will gradually decrease. When the actually detected exhaust temperature is less than or equal to the third temperature threshold, it is determined that most of the refrigeration oil has returned to the compressor.

[0099] Specifically, the process of determining the third temperature threshold is as follows: the exhaust temperature detected in real time and the corresponding third running time are obtained through step S151, the third running time is substituted into the objective function for calculation through step S152 to obtain the calculated value of the second exhaust temperature; finally, the calculated value of the second exhaust temperature is added to the preset third temperature difference △T2 through step S153 to obtain the third temperature threshold. Obtaining the third temperature threshold provides a reliable reference for determining whether most of the refrigeration oil has returned to the compressor.

[0100] It should be noted that the preset third temperature difference can be obtained through actual measurement, and the present application does not specifically limit the value of the third temperature difference ΔT2.

[0101] It can be understood that as the third operating time changes, the calculated value of the second exhaust temperature obtained in real time is also different, and thus the obtained third temperature threshold is also different. Dynamically determining the third temperature threshold makes the judgment on whether most of the refrigerating oil returns to the compressor more accurate.

[0102] Through step S154, when the exhaust temperature detected in real time is less than or equal to the third temperature threshold, it is determined that most of the refrigerating oil has returned to the compressor. At this time, the opening degrees of the respective electronic expansion valves are controlled to return to the initial opening degrees to prevent more liquid refrigerant from returning to the compressor; thus, the startup is completed, and then the compressor is controlled to operate at a third preset frequency, and the respective electronic expansion valves are controlled to return to the preset opening degrees on the basis of the initial opening degrees.

[0103] Further explanation through step S154, it can be understood that the auxiliary oil return control method for the air-conditioning system provided by the embodiments of the present application is applied to the startup stage of the compressor. When it is determined that most of the refrigerating oil has returned to the compressor, the auxiliary oil return to the compressor of the air-conditioning system is completed, and then the normal working mode will be entered (that is: controlling the compressor to operate at a third preset frequency, and controlling the respective electronic expansion valves to return to the preset opening degrees on the basis of the initial opening degrees). The frequency conversion methods of compressors of different manufacturers are different. In the normal working mode, different types of compressors will operate according to their own preset different frequency conversion logics. That is, the third preset frequencies of different types of compressors are different, and the present application does not specifically limit this.

[0104] Similarly, different manufacturers have different control logics for the electronic expansion valves in the normal working mode; thus, the preset opening degrees of the electronic expansion valves in the normal working mode are also different. Therefore, the embodiments of the present application do not specifically limit the preset opening degrees of the electronic expansion valves in the fourth working mode.

[0105] It can be understood that the control logic of the air-conditioning system is divided into startup control logic and normal operation control logic according to the operating state. The auxiliary oil return control method for the air-conditioning system provided by the embodiments of the present application can be applied to the startup control logic of different air-conditioning systems. After the startup is completed, the normal operation control logic of the air-conditioning system will be entered (that is, controlling the compressor to operate at a third preset frequency, and controlling the respective electronic expansion valves to return to the preset opening degrees on the basis of the initial opening degrees); different types of air-conditioning systems have different normal operation control logics, and the present application does not specifically limit the normal operation control logic of the air-conditioning system.

[0106] Through steps S151 to S154, the third temperature threshold obtained through real-time calculation is compared with the exhaust temperature detected in real time to determine whether most of the refrigerating oil has returned to the compressor; when most of the refrigerating oil has returned to the compressor, it is determined that the auxiliary oil return is completed, and the air-conditioning system is controlled to enter the fourth working mode.

[0107] Take an example to illustrate the specific process of the auxiliary oil return control method for the air-conditioning system provided by the embodiments of the present application.

[0108] First, set the first preset frequency to 42 Hz, the preset period to 120 s, the second preset frequency to 80 Hz, the preset second temperature difference △T1 to 19 °C, the preset second temperature difference △T2 to 2 °C, and the preset number of steps to 200 steps.

[0109] Then, the heating compressor starts. When it is determined that T 室外环境 <T 室内环境 and T 排气 <T 室外环境 + 5 °C, control the compressor to start running at the first preset frequency of 42 Hz and maintain the preset period of 120 s.

[0110] Then, within the preset period of 120 s, assume that when t1 = 0 s, T 排气1 = -12 °C, when t2 = 60 s, T 排气2 = 10 °C, when t3 = 120 s, T 排气3 = 20 °C are collected and substituted into the curve: It is solved that a = 0.1, h = -1, and k = -18. The specific expression of the objective function can be obtained as:

[0111] Next, after 120 s of the preset period, raise the compressor frequency to the second preset frequency of 80 Hz and continue to run. Assume that when running to the 180th second, the detected exhaust temperature T is 44 °C. Based on the objective function, the first exhaust temperature calculated value is 25 °C. Then add the first exhaust temperature calculated value to the second temperature difference to obtain the second temperature threshold: 25 + 19 = 44 °C. The exhaust temperature T collected at the 180th second is 44 °C, which satisfies the condition of being greater than or equal to the second temperature threshold (44 °C). It is considered that the liquid refrigerant has been completely emptied at this time.

[0112] Then, when it is determined that the liquid refrigerant has been completely emptied, the compressor frequency is restored to the first preset frequency of 42 Hz. Assume that at this time, the initial opening degree of the electronic expansion valve 1 is 120 steps, the initial opening degree of the electronic expansion valve 2 is 90 steps, and the initial opening degree of the electronic expansion valve 3 is 0 steps. All electronic expansion valves are additionally increased by 200 steps on the basis of their respective initial opening degrees, that is, the opening degrees of the electronic expansion valve 1, the electronic expansion valve 2, and the electronic expansion valve 3 are increased to 320 steps, 290 steps, and 200 steps respectively.

[0113] Next, assume that at the 190th second, the exhaust temperature T is detected to be 26 °C. Then, based on the objective function, the calculated value of the second exhaust temperature is 26 °C. Then, the calculated value of the second exhaust temperature is added to the third temperature difference to obtain the third temperature threshold: 26 + 2 = 28 °C. The exhaust temperature T detected at the 190th second is 26 °C, which satisfies the condition of being less than or equal to the third temperature threshold. Therefore, the opening degrees of the electronic expansion valve 1, the electronic expansion valve 2, and the electronic expansion valve 3 are restored to 120 steps, 90 steps, and 0 steps respectively, and then the normal control of each electronic expansion valve is restored on the basis of the initial opening degree; the compressor frequency also resumes normal control on the basis of the first preset frequency of 42 Hz. Specifically, when the auxiliary oil return control method provided by the embodiment of the present application is applied in the start-up stage of the air-conditioning system, during the entire compressor start-up process, the change curve of the exhaust temperature over time is as Figure 5 shown. When the auxiliary oil return control method provided by the embodiment of the present application is not applied in the start-up stage of the air-conditioning system, then during the entire compressor start-up process, the change curve of the exhaust temperature over time is as Figure 6 shown.

[0114] It can be seen that the auxiliary oil return control method for the air-conditioning system provided by the embodiment of the present application can solve the problem that the compressor is prone to long-term lack of oil during the start-up of heat generation with liquid and liquid accumulation in a multi-connected air-conditioning system without an air-liquid separator or an oil separator, achieving the beneficial effects of reducing costs, simplifying pipeline design, and improving energy efficiency. The auxiliary oil return control method for the air-conditioning system provided by the embodiment of the present application controls the operating frequency of the compressor and the opening degree of the electronic expansion valve, controls the liquid refrigerant to flow out of the compressor quickly, and makes the refrigeration oil flow back to the compressor quickly, avoiding the compressor being in a state of lack of oil for a long time and ensuring the operation stability of the compressor.

[0115] Combined with Figure 7 , take an example to illustrate the overall process of the auxiliary oil return control method for the air-conditioning system provided by the embodiment of the present application.

[0116] Step S701: After the compressor starts heating, or after the oil return ends or the defrosting ends, when the compressor starts heating, execute step S702.

[0117] Step S702: Determine whether T 室外环境 <T室内环境 and T 排气 <T 室外环境 +5 °C; if so, jump to step S703; if not, jump to step S711.

[0118] Step S703: Make the compressor run at the first preset frequency and maintain for a preset period.

[0119] Step S704: During the preset period of maintaining the first preset frequency operation, collect the exhaust temperatures T corresponding to the times t1, t2, and t3 at will 排气1 、T 排气2 、T 排气3 , substitute into the curve to obtain an objective function representing the corresponding relationship between the exhaust temperature T and the running time t of the compressor. After the preset period ends, execute step S705.

[0120] Step S705: Raise the compressor frequency to the second preset frequency and maintain it.

[0121] Step S706: Detect the exhaust temperature T1 at the running time t4, and substitute the value of the running time t4 into the objective function to calculate the first exhaust temperature calculated value T 计算值1 .

[0122] Step S707: Determine whether: the exhaust temperature T1 ≥ T 计算值1 +ΔT1; if so, jump to step S708; if not, jump to step S705.

[0123] Step S708: Restore the compressor frequency to the first preset frequency and maintain it, and at the same time increase the opening degrees of all expansion valves by a preset number of steps based on the current opening degrees and maintain them.

[0124] Step S709: Detect the exhaust temperature T2 at the running time t5, and substitute the value of the running time t5 into the objective function to calculate the second exhaust temperature calculated value T 计算值2 .

[0125] Step S710: Determine whether: the exhaust temperature T2 ≤ T 计算值2 +ΔT2; if so, jump to step S711; if not, jump to step S708.

[0126] Step S711: Restore all expansion valves to their original opening degrees, and resume normal adjustment based on the original opening degrees; restore the compressor frequency to normal adjustment based on the current frequency.

[0127] As Figure 8 shown, Figure 8 is a schematic diagram of the hardware structure of a controller provided by an embodiment of the present application. The present invention also provides a controller, including:

[0128] The processor 801 may be implemented as a general-purpose central processing unit (CPU), a microprocessor, an application-specific integrated circuit (ASIC), or one or more integrated circuits, and is configured to execute relevant programs to implement the technical solutions provided in the embodiments of the present application.

[0129] The memory 802 can be implemented in the form of a read-only memory (ROM), a static storage device, a dynamic storage device, or a random access memory (RAM). The memory 802 can store an operating system and other application programs. When the technical solutions provided in the embodiments of this specification are implemented through software or firmware, the relevant program code is stored in the memory 802 and is called by the processor 801 to execute the auxiliary oil return control method for the air conditioning system of the embodiments of this application.

[0130] Input / output interface 803, used to implement information input and output;

[0131] Communication interface 804, used to implement communication interaction between the apparatus and other devices, which can be achieved through wired means (such as USB, network cable, etc.) or wireless means (such as mobile network, WIFI, Bluetooth, etc.);

[0132] Bus 805 , which transmits information between various components of the device (e.g., processor 801 , memory 802 , input / output interface 803 , and communication interface 804 );

[0133] The processor 801 , the memory 802 , the input / output interface 803 and the communication interface 804 are connected to each other in communication within the device via a bus 805 .

[0134] The present application also provides an air conditioning system including the controller described above. The air conditioning system can implement auxiliary oil return control during startup, enabling auxiliary oil return without adding additional piping components. This reduces costs and piping design complexity, while also reducing compressor wear due to oil starvation and ensuring stable compressor operation.

[0135] An embodiment of the present application further provides a storage medium, which is a computer-readable storage medium and stores a computer program. When the computer program is executed by a processor, the above-mentioned auxiliary oil return control method for the air-conditioning system is implemented.

[0136] As a non-transitory computer-readable storage medium, the memory can be used to store non-transitory software programs and non-transitory computer-executable programs. In addition, the memory may include high-speed random access memory, and may also include non-transitory memory, such as at least one magnetic disk storage device, a flash memory device, or other non-transitory solid-state storage devices. In some embodiments, the memory may optionally include memories remotely located relative to the processor, and these remote memories can be connected to the processor through a network. Examples of the above networks include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network, and combinations thereof. The device embodiments described above are merely illustrative, where the units described as separate components may or may not be physically separated, and can be located in one place, or may also be distributed to multiple network units. Some or all of the modules can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0137] Those of ordinary skill in the art can understand that all or some of the steps and systems disclosed above can be implemented as software, firmware, hardware, and appropriate combinations thereof. Some physical components or all physical components can be implemented as software executed by a processor, such as a central processing unit, a digital signal processor, or a microprocessor, or can be implemented as hardware, or can be implemented as an integrated circuit, such as an application-specific integrated circuit. Such software can be distributed on a computer-readable medium, which can include a computer storage medium (or non-transitory medium) and a communication medium (or transitory medium). As is well known to those of ordinary skill in the art, the term computer storage medium includes volatile and non-volatile, removable and non-removable media implemented in any method or technology for storing information, such as computer-readable instructions, data structures, program modules, or other data. Computer storage media include, but are not limited to, RAM, ROM, EEPROM, flash memory or other memory technologies, CD-ROM, digital versatile disk (DVD) or other optical disk storage, magnetic cartridges, tapes, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to store the desired information and can be accessed by a computer. In addition, as is well known to those of ordinary skill in the art, a communication medium generally includes computer-readable instructions, data structures, program modules, or other data in a modulated data signal such as a carrier wave or other transmission mechanism, and can include any information delivery medium.

[0138] The above has specifically described the preferred embodiments of the present application, but the present application is not limited to the above embodiments. Those skilled in the art can also make various equivalent deformations or substitutions without departing from the spirit of the present application, and these equivalent deformations or substitutions are all included within the scope defined by the present application.

Claims

1. An auxiliary oil return control method for an air conditioning system, characterized in that, Including: In the case of a hot start of the compression mechanism, when the obtained outdoor ambient temperature is less than the obtained indoor ambient temperature and the exhaust temperature at the compressor exhaust port is less than the first temperature threshold, control the air-conditioning system to enter the first working mode; the first temperature threshold is obtained by adding the outdoor ambient temperature and a preset first temperature difference; In the first working mode, perform curve fitting on a preset quadratic function curve according to multiple groups of detected exhaust temperature detection values and corresponding first running times to obtain an objective function; the first running time is the duration from the start time to the detection time; the objective function is used to represent the corresponding relationship between the exhaust temperature T and the running time t of the compressor; After the first working mode ends, control the air-conditioning system to enter the second working mode; In the second working mode, when the detected exhaust temperature is greater than or equal to the second temperature threshold, control the air-conditioning system to enter the third working mode; wherein, the second temperature threshold is obtained by adding a first exhaust temperature calculation value calculated through the objective function and a preset second temperature difference; In the third working mode, when the detected exhaust temperature is less than or equal to the third temperature threshold, control the air-conditioning system to enter the fourth working mode; wherein, the third temperature threshold is obtained by adding a second exhaust temperature calculation value calculated through the objective function and a preset third temperature difference.

2. The auxiliary oil return control method for an air conditioning system according to claim 1, characterized in that The control for the air-conditioning system to enter the first working mode includes: Control the compressor to operate at a first preset frequency for a preset period.

3. The auxiliary oil return control method for an air conditioning system according to claim 1, wherein The performing curve fitting on a preset quadratic function curve according to multiple groups of detected exhaust temperature detection values and corresponding first running times in the first working mode to obtain an objective function includes: In the first working mode, obtain a preset quadratic function curve, multiple groups of exhaust temperature detection values and corresponding first running times; Substitute multiple groups of exhaust temperature detection values and corresponding first running times into the preset quadratic function curve to obtain the value of the parameter information to be solved in the preset quadratic function curve; Determine the objective function according to the value of the parameter information to be solved.

4. The auxiliary oil return control method for an air conditioning system according to claim 3, characterized in that The expression of the objective function is as follows: The parameter information to be solved includes: parameter a, parameter h, and parameter k. Among them, parameter a is used to characterize the opening size of the objective function, parameter h is used to characterize the horizontal translation amount of the objective function; parameter k is used to characterize the vertical translation amount of the objective function.

5. The auxiliary oil return control method for an air conditioning system according to claim 2, wherein The control for the air-conditioning system to enter the second working mode includes: Obtain a second preset frequency; the second preset frequency is greater than the first preset frequency; Control the compressor to operate at the second preset frequency.

6. The auxiliary oil return control method for an air conditioning system according to claim 2, wherein, The when the detected exhaust temperature is greater than or equal to the second temperature threshold, control the air-conditioning system to enter the third working mode includes: Obtain the detected exhaust temperature in real time and the corresponding second running time; the second running time is the duration from the start time to the detection time; Substitute the second running time into the objective function for calculation to obtain a first exhaust temperature calculation value; Add the first exhaust temperature calculation value and the preset second temperature difference to obtain the second temperature threshold; When the exhaust temperature detected in real time is greater than or equal to the second temperature threshold, control the compressor to resume operation at the first preset frequency, and control the opening degrees of the respective electronic expansion valves to increase by a preset number of steps based on the current initial opening degrees.

7. The auxiliary oil return control method for an air conditioning system according to claim 6, wherein When the exhaust temperature detected in real time is less than or equal to the third temperature threshold, control the air-conditioning system to enter the fourth working mode, including: Obtain the exhaust temperature detected in real time and the corresponding third running time; the third running time is the duration elapsed from the start time to the detection time; Substitute the third running time into the objective function for calculation to obtain a calculated value of the second exhaust temperature; Add the calculated value of the second exhaust temperature to the preset third temperature difference to obtain the third temperature threshold; When the exhaust temperature detected in real time is less than or equal to the third temperature threshold, control the opening degrees of the respective electronic expansion valves to resume to the initial opening degrees, control the compressor to operate at the third preset frequency, and control the respective electronic expansion valves to resume to the preset opening degrees based on the initial opening degrees.

8. A controller, characterized in that, Comprising at least one processor and a memory for communicatively connecting with the at least one processor; the memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor so that the at least one processor can execute the auxiliary oil return control method for an air-conditioning system according to any one of claims 1 to 7.

9. An air conditioning system, characterized in that, Comprising the controller according to claim 8.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer-executable instructions for causing a computer to execute the auxiliary oil return control method for an air-conditioning system according to any one of claims 1 to 7.

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