Air conditioner outdoor unit system, air conditioner system and oil return control method

Abstract

The invention provides an air conditioner outdoor unit system, an air conditioner system and a control method thereof, and belongs to the technical field of air conditioners. An outlet of a compressor of the air conditioner outdoor unit system is connected with an inlet of the oil separator, and a refrigerant outlet of the oil separator is connected with a first connector of the four-way valve. An inlet of the compressor is connected with a gas outlet pipe of the gas-liquid separator, and a gas inlet pipe of the gas-liquid separator is connected with a second connector of the four-way valve. A third connector of the four-way valve is connected with one end of the outdoor heat exchanger, and the other end of the outdoor heat exchanger is connected with the expansion valve. The other end of the expansion valve and a fourth connector of the four-way valve are used for being connected with an indoor unit. One end of the first pipeline and one end of the second pipeline are both connected with an oil outlet of the oil separator, the other end of the first pipeline is communicated with an air inlet of the compressor, the other end of the second pipeline is communicated with an air inlet pipe of the gas-liquid separator, and the second pipeline is provided with a control valve. And an oil return hole is formed in a gas outlet pipe of the gas-liquid separator. The performance of the indoor unit can be improved, and the problem of oil shortage of the compressor is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of air conditioners, and more particularly, to an outdoor unit system of an air conditioner and a method for controlling oil return of an air conditioning system. Background Art

[0002] For a multi-connected air conditioner, in the existing oil circulation system, the compressor is connected to an oil separator, the oil separator is connected to the compressor suction pipe through an oil return capillary, and at the same time, an oil return hole is provided at the lower end of the gas-liquid separator. It can return oil to the compressor, improving the reliability of oil return and preventing liquid return. However, its disadvantage is that when the oil discharge rate of the compressor is large, the amount of oil entering the indoor unit through the oil separator will be very large, which will cause an increase in the heat exchange and pressure drop of the indoor unit evaporator, a decrease in performance, and thus a decrease in the overall performance of the unit.

[0003] To improve performance, an improvement has been made on the above basis, such that the compressor is connected to an oil separator, the oil separator is connected to the inlet pipeline of the gas-liquid separator through an oil return capillary, and at the same time, an oil return hole is provided at the lower end of the gas-liquid separator. When the oil discharge rate of the compressor is large, the amount of oil entering the indoor unit through the oil separator can be reduced, thereby improving the performance of the indoor unit and the overall performance of the unit. However, the oil return of this system is ensured by the flow rate. When the compressor operates at a low frequency, the flow rate is not sufficient to ensure continuous oil return, which will cause a risk of oil shortage in the compressor.

[0004] It can be seen that neither of the above two technologies can simultaneously achieve the problems of improving the performance of the indoor unit and avoiding oil shortage in the compressor. Summary of the Invention

[0005] The problem to be solved by the present invention is how to better achieve the problems of improving the performance of the indoor unit and avoiding oil shortage in the compressor.

[0006] To solve the above problems, an embodiment of the present invention provides an outdoor unit system of an air conditioner and an oil return control method, which can avoid the problem of oil shortage in the compressor while improving the performance of the indoor unit.

[0007] In a first aspect, the present invention provides an outdoor unit system of an air conditioner, including a compressor, an oil separator, a four-way valve, a gas-liquid separator, an outdoor heat exchanger, an expansion valve, a first pipeline, a second pipeline, a liquid valve, and a gas valve;

[0008] The outlet of the compressor is connected to the inlet of the oil separator, and the refrigerant discharge port of the oil separator is connected to the first interface of the four-way valve;

[0009] The inlet of the compressor is connected to the outlet pipe of the gas-liquid separator, and the inlet pipe of the gas-liquid separator is connected to the second interface of the four-way valve;

[0010] The third interface of the four-way valve is connected to one end of the outdoor heat exchanger, and the other end of the outdoor heat exchanger is connected to the expansion valve;

[0011] The other end of the expansion valve is connected to the liquid valve, and the fourth port of the four-way valve is connected to the gas valve;

[0012] One end of each of the first pipeline and the second pipeline is connected to the oil discharge port of the oil separator. The other end of the first pipeline communicates with the intake port of the compressor, and the other end of the second pipeline communicates with the intake pipe of the gas-liquid separator. A control valve is provided on the second pipeline;

[0013] An oil return hole is provided on the outlet pipe of the gas-liquid separator.

[0014] In this application, by connecting one end of each of the first pipeline and the second pipeline to the oil discharge port of the oil separator, the other end of the first pipeline communicates with the intake port of the compressor, the other end of the second pipeline communicates with the intake pipe of the gas-liquid separator, and a control valve is provided on the second pipeline. In this way, when the compressor frequency is high and the oil discharge rate is large, the gas control valve can be opened so that the excess oil in the oil separator enters the gas-liquid separator, thereby reducing the amount of oil entering the indoor unit, improving the heat exchange performance of the indoor unit and reducing the thermal resistance. Secondly, opening the control valve is equivalent to adding a bypass between the high and low pressures, thereby reducing the high pressure and increasing the low pressure. When the high pressure decreases, the performance of the compressor will improve. When the low pressure rises, the return gas density and mass flow rate of the system will increase, thereby improving the performance of the whole machine. When the compressor operates at medium and low frequencies, the problem of compressor oil shortage can be avoided by closing the control valve.

[0015] In an alternative embodiment, the outdoor unit system of the air conditioner further includes a first capillary tube and a second capillary tube;

[0016] The first capillary tube is disposed in the first pipeline, and the second capillary tube is disposed in the second pipeline.

[0017] The provision of the first capillary tube and the second capillary tube in this application can achieve throttling.

[0018] In an alternative embodiment, the volume of the gas-liquid separator is A liters;

[0019] When the value range of A is between 0 and 10, the diameter value range of the oil return hole is between 1 mm and 2 mm;

[0020] When the value range of A is between 10 and 20, the diameter value range of the oil return hole is between 1.5 mm and 2.5 mm;

[0021] When the value range of A is between 20 and 30, the diameter value range of the oil return hole is between 1.5 mm and 3 mm.

[0022] Correspondingly setting the diameter of the oil return hole of the gas-liquid separator according to the capacity of the gas-liquid separator can better achieve oil return when the control valve is in the open state.

[0023] In an alternative embodiment, the volume of the gas-liquid separator is A liters;

[0024] When the value range of A is between 0 and 10, the height range of the oil return hole from the bottom surface of the gas-liquid separator is 10 mm - 25 mm;

[0025] When the value range of A is between 10 and 20, the height range of the oil return hole from the bottom surface of the gas-liquid separator is 15 mm - 35 mm;

[0026] When the value range of A is between 20 and 30, the height range of the oil return hole from the bottom surface of the gas-liquid separator is 20 mm - 50 mm.

[0027] Correspondingly setting the position of the oil return hole in the gas-liquid separator according to the capacity of the gas-liquid separator can better achieve oil return when the control valve is in the open state.

[0028] In an alternative embodiment, the outdoor unit system of the air conditioner further includes a temperature sensor, and the temperature sensor is arranged on the first pipeline to detect the temperature of the refrigerant in the first pipeline.

[0029] In this application, the temperature sensor can be used to detect whether the outdoor unit system of the air conditioner lacks oil.

[0030] In a second aspect, the present invention provides an air conditioning system, including the outdoor unit system of the air conditioner according to any one of the foregoing embodiments and at least one indoor unit;

[0031] The indoor unit is connected between the expansion valve and the fourth interface of the four-way valve.

[0032] In this application, the air conditioning system can open the gas control valve when the compressor frequency is high and the oil discharge rate is large, so that the excess oil in the oil separator enters the gas-liquid separator, thereby reducing the amount of oil entering the indoor unit, improving the heat exchange performance of the indoor unit and reducing the thermal resistance. When the compressor operates at medium and low frequencies, the control valve can be closed to avoid the problem of oil shortage in the compressor.

[0033] In a third aspect, the present invention provides an oil return control method for an air conditioning system, which is applied to the air conditioning system according to the foregoing embodiments, and the method includes:

[0034] Obtain the operating load and the outer ring temperature of the indoor unit;

[0035] Control the opening or closing of the control valve according to the operating mode of the air conditioning system, the operating load and the outer ring temperature.

[0036] This application controls the operation of the control valve based on the operating mode, operating load, and outer ring temperature of the air conditioning system, so that the control valve can be opened when the requirements for the operating performance of the indoor unit are relatively high, thereby improving the operating performance of the indoor unit.

[0037] In an alternative embodiment, the step of controlling the opening or closing of the control valve based on the operating mode, the operating load, and the outer ring temperature of the air conditioning system includes:

[0038] Determine whether the air conditioning system is in the cooling operation mode;

[0039] If the air conditioning system is in the cooling mode, determine the load range where the operating load is located and the temperature range where the outer ring temperature is located;

[0040] If it simultaneously satisfies that the operating load is greater than the first target load and the outer ring temperature is greater than the first preset temperature, control the control valve to open;

[0041] If it simultaneously satisfies that the operating load is less than the second target load and the outer ring temperature is less than the second preset temperature, control the control valve to close;

[0042] If the operating load is between the first target load and the second target load, and the outer ring temperature is between the first preset temperature and the second preset temperature, keep the control valve in its current state;

[0043] Wherein, the first target load is greater than the second target load, and the first preset temperature is greater than the second preset temperature.

[0044] The higher the outer ring temperature of the air conditioning system in the cooling mode and the greater the load of the indoor unit, the higher the heat exchange performance required for the indoor unit. At this time, opening the control valve can improve the performance of the indoor unit. In the cooling state, when the outer ring temperature is low and the load of the indoor unit is low, the demand for the heat exchange amount is low, and closing the control valve can avoid the problem of compressor oil shortage. When the operating load is between the first target load and the second target load, and the outer ring temperature is between the first preset temperature and the second preset temperature, the air conditioning system can operate more stably and avoid frequent start and stop of the control valve.

[0045] In an alternative embodiment, the step of controlling the opening or closing of the control valve based on the operating mode, the operating load, and the outer ring temperature of the air conditioning system further includes:

[0046] Determine whether the air conditioning system is in the heating operation mode;

[0047] If the air conditioning system is in the heating mode, determine the load range where the operating load is located and the temperature range where the outer ring temperature is located;

[0048] If the operating load is greater than the third target load and the outer ring temperature is less than the third preset temperature at the same time, then control the control valve to open;

[0049] If the operating load is less than the fourth target load and the outer ring temperature is greater than the fourth preset temperature at the same time, then control the control valve to close;

[0050] If the operating load is between the third target load and the fourth target load, and the outer ring temperature is between the third preset temperature and the fourth preset temperature, then keep the control valve in the current state;

[0051] Wherein, the third target load is greater than the fourth target load, and the third preset temperature is greater than the fourth preset temperature; and / or,

[0052] The method further includes:

[0053] Judge whether the air conditioning system is in the defrosting operation mode;

[0054] If the air conditioner system is operating in the defrosting mode, control the control valve to close.

[0055] The lower the outer ring temperature of the air conditioning system in the heating mode, and the greater the indoor unit load, the higher the heat exchange performance required for the indoor unit. At this time, opening the control valve can improve the performance of the indoor unit. When the outer ring temperature is high and the indoor unit load is low in the heating state, the demand for heat exchange is low at this time, and closing the control valve can avoid the problem of compressor oil shortage. When the operating load is between the third target load and the fourth target load, and the outer ring temperature is between the third preset temperature and the fourth preset temperature, then keep the control valve in the current state, which can maintain the stability of the air conditioning system operation and avoid frequent start and stop of the control valve. When the air conditioner system is operating in the defrosting mode, controlling the control valve to close can avoid compressor oil shortage.

[0056] In an alternative embodiment, the step of obtaining the operating load and the outer ring temperature of the indoor unit includes:

[0057] After the air conditioning system is started, close the control valve, and obtain the operating load and the outer ring temperature of the indoor unit after a first preset time.

[0058] Since the operation of the air conditioning system is not stable when it is just started, closing the control valve at this time can ensure that the compressor does not lack oil. Obtaining data after the first preset time is convenient for accurate data.

[0059] In an alternative embodiment, the air conditioning system includes a plurality of parallel air conditioner outdoor unit systems;

[0060] The step of controlling the opening or closing of the control valve according to the operating mode of the air conditioning system, the operating load and the outer ring temperature includes:

[0061] Controlling all the control valves of all the outdoor air conditioner systems to open or close simultaneously according to the operating mode of the air conditioning system, the operating load and the outer ring temperature.

[0062] Simultaneously opening or closing all the solenoid valves of multiple parallel outdoor air conditioner systems, which can avoid the problem of unbalanced system operation caused by the opening of the control valves of some outdoor air conditioner systems and the closing of the control valves of some outdoor air conditioner systems.

[0063] In an alternative embodiment, the outdoor air conditioner system further includes a temperature sensor disposed in the first pipeline to detect the temperature of the refrigerant in the first pipeline;

[0064] The method further includes:

[0065] Obtaining the actual oil temperature in the first pipeline of each outdoor unit system through the temperature sensor disposed in the first pipeline;

[0066] Judging whether the actual oil temperature of each outdoor unit system is less than the corresponding target oil temperature; wherein, the target oil temperature characterizes the operating condition of the compressor in the outdoor unit system, and the target oil temperature corresponds to the compressor one by one;

[0067] If the actual oil temperature of any outdoor unit system is less than the target oil temperature, controlling all the control valves to open, controlling the compressor frequency to increase, controlling the opening degree of the expansion valve to increase, and controlling the opening degree of the indoor expansion valve to increase, and maintaining for a first preset time.

[0068] When the temperature sensor detects oil shortage, the above control method can quickly return the oil in the indoor unit to the outdoor unit, thereby avoiding the problem of oil shortage.

[0069] In an alternative embodiment, the target oil temperature is calculated according to the following formula:

[0070] T j = E * Td + B * Pd + C * Ps + D

[0071] Wherein, T j is the target oil temperature, Td is the exhaust gas temperature, Pd is the exhaust gas pressure, and Ps is the suction gas pressure;

[0072] E, B, C, D are constants, and E is positively correlated with T j B is negatively correlated with T j C is positively correlated with T j D is positively correlated with Tj Positively correlated.

[0073] The target oil temperature is calculated through the above formula, so as to accurately determine whether there is insufficient oil.

[0074] In an optional embodiment, the steps of controlling the compressor frequency to increase, controlling the opening degree of the expansion valve to increase, controlling the opening degree of the indoor expansion valve to increase, and maintaining for a first preset time include:

[0075] Control the compressor frequency to increase to 50% of the maximum operating frequency of the compressor, control the opening degree of the expansion valve to increase to 70% of the maximum opening degree, the opening degree of the indoor expansion valve to increase to 70% of the maximum opening degree, and maintain the first preset time, where the first preset time is greater than or equal to 3 minutes.

[0076] Through the above method, oil return can be quickly achieved, thus avoiding the occurrence of insufficient oil and lack of oil problems. Description of the Drawings

[0077] Figure 1 Schematic diagram of the pipeline connection of the outdoor unit system provided by the embodiment of the present invention;

[0078] Figure 2 Schematic diagram of the pipeline connection of the air conditioning system provided by the embodiment of the present invention.

[0079] Description of the reference numerals: 100 - air conditioning system; 1 - outdoor unit system of the air conditioner; 2 - compressor; 3 - oil separator; 4 - four-way valve; 5 - gas-liquid separator; 6 - outdoor heat exchanger; 7 - expansion valve; 8 - first pipeline; 9 - second pipeline; 10 - control valve; 11 - oil return hole; 13 - first capillary tube; 14 - second capillary tube; 15 - plate heat exchanger; 16 - subcooling expansion valve; 17 - liquid valve; 18 - gas valve; 19 - bypass valve; 20 - check valve; 21 - indoor unit; 22 - indoor expansion valve; 23 - temperature sensor. Detailed Embodiments

[0080] To solve the problem that the performance of the indoor unit cannot be improved and the compressor lacks oil at the same time in the existing air conditioning system. The embodiment of the present invention provides an outdoor unit system of an air conditioner and its oil return control method, which can improve the performance of the indoor unit 21 and also avoid the problem of the compressor lacking oil.

[0081] To make the above objects, features and advantages of the present invention more obvious and understandable, the following detailed description of the specific embodiments of the present invention will be given with reference to the drawings.

[0082] Please refer to Figure 1 and Figure 2, in this embodiment, the air - conditioning system 100 includes an outdoor unit system 1 and at least one indoor unit 21. The outdoor unit system 1 includes a compressor 2, an oil separator 3, a four - way valve 4, a gas - liquid separator 5, an outdoor heat exchanger 6, an expansion valve 7, a first pipe 8, a second pipe 9, and at least one indoor unit 21. The outlet of the compressor 2 is connected to the inlet of the oil separator 3, and the refrigerant discharge port of the oil separator 3 is connected to the first interface of the four - way valve 4. The inlet of the compressor 2 is connected to the outlet pipe of the gas - liquid separator 5, and the inlet pipe of the gas - liquid separator 5 is connected to the second interface of the four - way valve 4. The third interface of the four - way valve 4 is connected to one end of the outdoor heat exchanger 6, and the other end of the outdoor heat exchanger 6 is connected to the expansion valve 7. The other end of the expansion valve 7 and the fourth interface of the four - way valve 4 are connected to the indoor unit 21. One ends of the first pipe 8 and the second pipe 9 are both connected to the oil discharge port of the oil separator 3. The other end of the first pipe 8 is communicated with the inlet of the compressor 2, and the other end of the second pipe 9 is communicated with the inlet pipe of the gas - liquid separator 5. A control valve 10 is provided on the second pipe 9. An oil return hole 11 is provided on the outlet pipe of the gas - liquid separator 5.

[0083] In this embodiment, by connecting one ends of the first pipe 8 and the second pipe 9 to the oil discharge port of the oil separator 3, connecting the other end of the first pipe 8 to the inlet of the compressor 2, connecting the other end of the second pipe 9 to the inlet pipe of the gas - liquid separator 5, and providing a control valve 10 on the second pipe 9, when the frequency of the compressor 2 is high and the oil discharge rate is large, the control valve 10 can be opened, so that the excess oil in the oil separator 3 enters the gas - liquid separator 5, thereby reducing the amount of oil entering the indoor unit 21, improving the heat exchange performance of the indoor unit and reducing the thermal resistance. Secondly, opening the control valve 10 is equivalent to adding a bypass between the high - pressure and low - pressure, thereby reducing the high - pressure and increasing the low - pressure. When the high - pressure decreases, the performance of the compressor 2 will improve. When the low - pressure rises, the return gas density and mass flow rate of the system will increase, thereby improving the overall performance of the unit. When the compressor 2 operates at medium and low frequencies, the control valve 10 can be closed to avoid the problem of oil shortage in the compressor 2.

[0084] It should be noted that in this application, the outdoor unit system 1 is equivalent to the outdoor unit. In a multi - connected air conditioner, multiple parallel outdoor unit systems 1 can be connected in parallel to form the outdoor unit. The number of indoor units 21 can also include multiple units connected in parallel, which are controlled by an indoor expansion valve 22.

[0085] Please refer to Figure 1 , in this embodiment, the outdoor unit system 1 further includes a first capillary tube 13 and a second capillary tube 14. The first capillary tube 13 is provided on the first pipe 8, and the second capillary tube 14 is provided on the second pipe 9. In this embodiment, throttling can be achieved by providing the first capillary tube 13 and the second capillary tube 14.

[0086] In this embodiment, the volume of the gas-liquid separator 5 is A liters. When the value range of A is between 0 and 10, the diameter value range of the oil return hole 11 is 1 mm - 2 mm. When the value range of A is between 10 and 20, the diameter value range of the oil return hole 11 is 1.5 mm - 2.5 mm. When the value range of A is between 20 and 30, the diameter value range of the oil return hole 11 is 1.5 mm - 3 mm. When the value range of A is between 0 and 10, the height value range of the oil return hole 11 from the bottom surface of the gas-liquid separator 5 is 10 mm - 25 mm. When the value range of A is between 10 and 20, the height value range of the oil return hole 11 from the bottom surface of the gas-liquid separator 5 is 15 mm - 35 mm. When the value range of A is between 20 and 30, the height value range of the oil return hole 11 from the bottom surface of the gas-liquid separator 5 is 20 mm - 50 mm.

[0087] Correspondingly set the diameter and height of the oil return hole 11 of the gas-liquid separator 5 according to the capacity of the gas-liquid separator 5, which can better realize oil return when the control valve 10 is in the open state.

[0088] In this embodiment, the control valve 10 is a solenoid valve, which can be conveniently controlled.

[0089] Please refer to Figure 1 and Figure 2 , in this embodiment, the outdoor unit system 1 of the air conditioner further includes a plate heat exchanger 15, a subcooling expansion valve 16, a liquid valve 17, a gas valve 18, a bypass valve 19 and a check valve 20. One end of the expansion valve 7 away from the outdoor heat exchanger 6 is connected to the liquid valve 17, the fourth interface of the four-way valve 4 is connected to the gas valve 18, and the gas valve 18 and the liquid valve 17 are connected to the indoor unit 21. The plate heat exchanger 15 is connected between the expansion valve 7 and the liquid valve 17. A heat exchange pipeline is led out from one side of the expansion valve 7 away from the heat exchanger, and a subcooling expansion valve 16 is provided. The outlet side of the heat exchange pipeline is connected to the inlet of the liquid separator of the gas separator after heat exchange with the plate heat exchanger 15. A filter is provided on the inlet side of the gas-liquid separator 5, and the filter is connected to a bypass circuit which is connected to the outlet of the oil separator 3. The bypass valve 19 is provided in the bypass circuit. The check valve 20 is provided between the oil separator 3 and the four-way valve 4.

[0090] Please refer to Figure 1 and Figure 2 , for the above air conditioner system 100, this embodiment provides an oil return control method for the air conditioner system 100, which is applied to the air conditioner system 100 in the above implementation manner. The method includes:

[0091] S1. Obtain the operating load, outdoor temperature and operating mode of the indoor unit 21;

[0092] S2. Control the opening or closing of the control valve 10 according to the operating mode, operating load and outdoor temperature of the air conditioner system 100.

[0093] In this embodiment, by controlling the operation of the control valve 10 according to the operation mode, operation load, and outer loop temperature of the air conditioning system 100, the control valve 10 can be opened when the requirements for the operation performance of the indoor unit are relatively high, so as to improve the operation performance of the indoor unit.

[0094] In this embodiment, step S2 includes the following sub-steps:

[0095] S21. Determine whether the air conditioning system 100 is operating in the cooling mode;

[0096] S23. If the air conditioning system 100 is in the cooling mode, determine the load range where the operation load is located and the temperature range where the outer loop temperature is located;

[0097] S25. If it simultaneously satisfies that the operation load is greater than the first target load and the outer loop temperature is greater than the first preset temperature, control the control valve 10 to open;

[0098] S27. If it simultaneously satisfies that the operation load is less than the second target load and the outer loop temperature is less than the second preset temperature, control the control valve 10 to close;

[0099] S29. If the operation load is between the first target load and the second target load, and the outer loop temperature is between the first preset temperature and the second preset temperature, keep the control valve 10 in the current state;

[0100] Wherein, the first target load is greater than the second target load, and the first preset temperature is greater than the second preset temperature.

[0101] In this embodiment, the first target load is 50%, and the second target load is 20%. The first preset temperature is 30 °C, and the second preset temperature is 10 °C. Of course, in some other embodiments of the present application, the values of the first target load, the second target load, the first preset temperature, and the second preset temperature can also be set according to the air conditioning system 100.

[0102] The higher the outer loop temperature of the air conditioning system 100 in the cooling mode and the greater the load of the indoor unit 21, the higher the heat exchange performance required for the indoor unit 21. At this time, opening the control valve 10 can improve the performance of the indoor unit. In the cooling state, when the outer loop temperature is low and the load of the indoor unit 21 is low, the demand for the heat exchange amount is low, and closing the control valve 10 can avoid the problem of oil shortage of the compressor 2. When the operation load is between the first target load and the second target load, and the outer loop temperature is between the first preset temperature and the second preset temperature, the air conditioning system 100 can operate more stably, and the frequent start and stop of the control valve 10 can be avoided.

[0103] In this embodiment, step S2 further includes the following sub-steps:

[0104] S31. Determine whether the air conditioning system 100 is operating in the heating mode;

[0105] S33. If the air conditioning system 100 is in the heating mode, determine the load range where the operating load is located and the temperature range where the outer ring temperature is located;

[0106] S35. If it simultaneously satisfies that the operating load is greater than the third target load and the outer ring temperature is less than the third preset temperature, control the control valve 10 to open;

[0107] S37. If it simultaneously satisfies that the operating load is less than the fourth target load and the outer ring temperature is greater than the fourth preset temperature, control the control valve 10 to close;

[0108] S39. If the operating load is between the third target load and the fourth target load, and the outer ring temperature is between the third preset temperature and the fourth preset temperature, keep the control valve 10 in the current state;

[0109] Wherein, the third target load is greater than the fourth target load, and the fourth preset temperature is greater than the fourth preset temperature.

[0110] The method further includes:

[0111] S41. Determine whether the air conditioning system 100 is operating in the defrosting mode;

[0112] S43. If the air conditioner system is operating in the defrosting mode, and control the control valve 10 to close.

[0113] In this embodiment, the third target load is 50%, and the fourth target load is 20%. The third preset temperature is 10°C, and the fourth preset temperature is 15°C. Of course, in some other embodiments of the present application, the values of the first target load, the second target load, the first preset temperature, and the second preset temperature can also be set separately according to the air conditioning system 100.

[0114] Of course, to ensure the reliable operation of the air conditioning system 100, the control valve 10 can also be closed during startup, mode conversion, etc.

[0115] The lower the outdoor ambient temperature and the greater the load of the indoor unit 21 in the heating mode of the air conditioning system 100, the higher the heat exchange performance required for the indoor unit 21. At this time, opening the control valve 10 can improve the performance of the indoor unit. When the outdoor ambient temperature is high and the load of the indoor unit 21 is low in the heating state, the demand for the heat exchange amount is low, and closing the control valve 10 can avoid the problem of oil shortage in the compressor 2. When the operating load is between the third target load and the fourth target load, and the outdoor ambient temperature is between the third preset temperature and the fourth preset temperature, the control valve 10 is maintained in the current state, which can maintain the stability of the operation of the air conditioning system 100 and avoid frequent start and stop of the control valve 10. When the air conditioner system operates in the defrosting mode, the control valve 10 is controlled to close to avoid oil shortage in the compressor 2.

[0116] In this embodiment, step S1 includes the following sub-steps:

[0117] S11. After the air conditioning system 100 is started, close the control valve 10, and obtain the operating load and outdoor ambient temperature of the indoor unit 21 after the first preset time.

[0118] Since the operation of the air conditioning system 100 is not stable when it is just started, closing the control valve 10 at this time can ensure that the compressor does not lack oil. Obtaining data after the first preset time is convenient for accurate data.

[0119] In this embodiment, the air conditioning system 100 includes a plurality of parallel air conditioner outdoor systems 1;

[0120] The steps of controlling the opening or closing of the control valve 10 according to the operation mode, operating load and outdoor ambient temperature of the air conditioning system 100 include:

[0121] Control all the control valves 10 of all the air conditioner outdoor systems 1 to open or close simultaneously according to the operation mode, operating load and outdoor ambient temperature of the air conditioning system 100.

[0122] Simultaneously open or close all the solenoid valves of the multiple parallel air conditioner outdoor systems 1, which can avoid the problem of unbalanced system operation caused by some control valves 10 of the air conditioner outdoor systems 1 being open and some control valves 10 of the air conditioner outdoor systems 1 being closed.

[0123] In this embodiment, the air conditioner outdoor system 1 further includes a temperature sensor 23, and the temperature sensor 23 is arranged on the first pipeline 8 to detect the temperature of the refrigerant in the first pipeline 8;

[0124] The method further includes the following steps:

[0125] S5. Obtain the actual oil temperature in the first pipeline 8 of each outdoor system through the temperature sensor 23 arranged on the first pipeline 8;

[0126] S6. Determine whether the actual oil temperature of each of the outdoor unit systems is less than the corresponding target oil temperature; wherein, the target oil temperature characterizes the operating condition of the compressor 2 in the outdoor unit system, and the target oil temperature corresponds one-to-one with the compressor 2;

[0127] S7. If the actual oil temperature of any of the outdoor unit systems is less than the target oil temperature, control all the control valves 10 to open, control the frequency of the compressor 2 to increase, control the opening degree of the expansion valve 7 to increase, and control the opening degree of the indoor expansion valve 22 to increase, and maintain for a first preset time.

[0128] When the oil shortage is detected by the temperature sensor 23, the oil in the indoor unit can be quickly returned to the outdoor unit through the above control method, thus avoiding the problem of oil shortage.

[0129] It should be noted that when the oil shortage is detected by the temperature sensor, the control of S7 is achieved through priority control, so that the oil can quickly return to the outdoor unit.

[0130] In this embodiment, the target oil temperature is calculated according to the following formula:

[0131] Tj = E * Td + B * Pd + C * Ps + D

[0132] wherein, Tj is the target oil temperature, Td is the exhaust gas temperature, Pd is the exhaust gas pressure, and Ps is the suction gas pressure;

[0133] E, B, C, and D are constants, and E is positively correlated with Tj, B is negatively correlated with Tj, C is positively correlated with Tj, and D is positively correlated with Tj.

[0134] The target oil temperature is calculated through the above formula, so as to accurately determine whether there is less oil.

[0135] In this embodiment, in the refrigeration mode of the air conditioning system 100, the value range of E is 5 to 10, the value range of B is -3 to -1, and the value range of C is 3 to 5; in the heating mode of the air conditioning system 100, the value range of E is 1 to 5, the value range of B is -5 to -3, and the value range of C is 1 to 3.

[0136] In an alternative embodiment, the step of controlling the frequency of the compressor 2 to increase, controlling the opening degree of the expansion valve 7 to increase, controlling the opening degree of the indoor expansion valve 22 to increase, and maintaining for a first preset time includes:

[0137] Control the frequency of the compressor 2 to increase to 50% of the maximum operating frequency of the compressor 2, control the opening degree of the expansion valve to increase to 70% of the maximum opening degree, and the opening degree of the indoor expansion valve 22 to increase to 70% of the maximum opening degree, and maintain the first preset time, where the first preset time is greater than or equal to 3 minutes.

[0138] By the above method, oil return can be quickly achieved, thus avoiding the problems of less oil and lack of oil.

[0139] In summary, the working principles and beneficial effects of the outdoor unit system 1, the air-conditioning system 100 and their control methods provided in this embodiment include:

[0140] In this embodiment, one ends of the first pipeline 8 and the second pipeline 9 are both connected to the oil discharge port of the oil separator 3, the other end of the first pipeline 8 is communicated with the air inlet of the compressor 2, the other end of the second pipeline 9 is communicated with the intake pipe of the gas-liquid separator 5, and a control valve 10 is provided on the second pipeline 9. With such a setting, when the frequency of the compressor 2 is high and the oil discharge rate is large, the air control valve 10 can be opened, so that the excess oil in the oil separator 3 enters the gas-liquid separator 5, thereby reducing the amount of oil entering the indoor unit 21, improving the heat exchange performance of the indoor unit and reducing the thermal resistance. Secondly, opening the control valve 10 is equivalent to adding a bypass between the high and low pressures, thereby reducing the high pressure and increasing the low pressure. When the high pressure decreases, the performance of the compressor 2 will improve, and when the low pressure rises, the suction gas density and mass flow rate of the system will increase, thereby improving the performance of the whole machine. When the compressor 2 operates at medium and low frequencies, the control valve 10 can be closed to avoid the problem of lack of oil in the compressor 2.

[0141] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention should be subject to the scope defined by the claims.

Claims

1. An outdoor unit system of an air conditioner, characterized in that, it includes a compressor, an oil separator, a four-way valve, a gas-liquid separator, an outdoor heat exchanger, an expansion valve, a first pipe, a second pipe, a liquid valve and a gas valve; The outlet of the compressor is connected to the inlet of the oil separator, and the refrigerant discharge port of the oil separator is connected to the first interface of the four-way valve; The inlet of the compressor is connected to the outlet pipe of the gas-liquid separator, and the inlet pipe of the gas-liquid separator is connected to the second interface of the four-way valve; The third interface of the four-way valve is connected to one end of the outdoor heat exchanger, and the other end of the outdoor heat exchanger is connected to the expansion valve; The other end of the expansion valve is connected to the liquid valve, and the fourth interface of the four-way valve is connected to the gas valve; One end of the first pipe and the second pipe is connected to the oil discharge port of the oil separator, the other end of the first pipe is communicated with the air inlet of the compressor, the other end of the second pipe is communicated with the inlet pipe of the gas-liquid separator, and a control valve is arranged on the second pipe; An oil return hole is arranged on the outlet pipe of the gas-liquid separator.

2. The outdoor unit system of an air conditioner according to claim 1, characterized in that, the outdoor unit system of the air conditioner further includes a first capillary tube and a second capillary tube; The first capillary tube is arranged in the first pipe, and the second capillary tube is arranged in the second pipe.

3. The outdoor unit system of an air conditioner according to claim 1, characterized in that, the volume of the gas-liquid separator is A liters; When the value range of A is between 0 and 10, the diameter value range of the oil return hole is between 1mm and 2mm; When the value range of A is between 10 and 20, the diameter value range of the oil return hole is between 1.5mm and 2.5mm; When the value range of A is between 20 and 30, the diameter value range of the oil return hole is between 1.5mm and 3mm.

4. The outdoor unit system of an air conditioner according to claim 1, characterized in that, the volume of the gas-liquid separator is A liters; When the value range of A is between 0 and 10, the height value range of the oil return hole from the bottom surface of the gas-liquid separator is between 10mm and 25mm; When the value range of A is between 10 and 20, the height value range of the oil return hole from the bottom surface of the gas-liquid separator is between 15mm and 35mm; When the value range of A is between 20 and 30, the height value range of the oil return hole from the bottom surface of the gas-liquid separator is between 20mm and 50mm.

5. The outdoor unit system of an air conditioner according to any one of claims 1-4, characterized in that, the outdoor unit system of the air conditioner further includes a temperature sensor, and the temperature sensor is arranged in the first pipe to detect the temperature of the refrigerant in the first pipe.

6. An air conditioner system, characterized in that, it includes the outdoor unit system of an air conditioner according to any one of claims 1-5 and at least one indoor unit, and an indoor expansion valve is correspondingly arranged on the indoor unit; The indoor unit is connected between the gas valve and the liquid valve.

7. An oil return control method for an air conditioner system, characterized in that, applied to the air conditioner system according to claim 6, the method includes: Obtain the operating load, outer loop temperature, and operating mode of the indoor unit; Control the opening or closing of the control valve according to the operating mode of the air conditioning system, the operating load, and the outer loop temperature.

8. The air conditioning system oil return control method according to claim 7, characterized in that, The step of controlling the opening or closing of the control valve according to the operating mode of the air conditioning system, the operating load, and the outer loop temperature includes: Judge whether the air conditioning system is in the cooling operation mode; If the air conditioning system is in the cooling mode, judge the load range where the operating load is located and the temperature range where the outer loop temperature is located; If it simultaneously satisfies that the operating load is greater than the first target load and the outer loop temperature is greater than the first preset temperature, control the control valve to open; If it simultaneously satisfies that the operating load is less than the second target load and the outer loop temperature is less than the second preset temperature, control the control valve to close; If the operating load is between the first target load and the second target load, and the outer loop temperature is between the first preset temperature and the second preset temperature, keep the control valve in the current state; Wherein, the first target load is greater than the second target load, and the first preset temperature is greater than the second preset temperature.

9. The air conditioning system oil return control method according to claim 8, characterized in that, The step of controlling the opening or closing of the control valve according to the operating mode of the air conditioning system, the operating load, and the outer loop temperature further includes: Judge whether the air conditioning system is in the heating operation mode; If the air conditioning system is in the heating mode, judge the load range where the operating load is located and the temperature range where the outer loop temperature is located; If it simultaneously satisfies that the operating load is greater than the third target load and the outer loop temperature is less than the third preset temperature, control the control valve to open; If it simultaneously satisfies that the operating load is less than the fourth target load and the outer loop temperature is greater than the fourth preset temperature, control the control valve to close; If the operating load is between the third target load and the fourth target load, and the outer loop temperature is between the third preset temperature and the fourth preset temperature, keep the control valve in the current state; Wherein, the third target load is greater than the fourth target load, and the third preset temperature is greater than the fourth preset temperature; and / or, The method further includes: Judge whether the air conditioning system is in the defrosting operation mode; If the air conditioning system is operating in the defrosting mode, control the control valve to close.

10. The air conditioning system oil return control method according to claim 7, characterized in that, The step of obtaining the operating load and outer loop temperature of the indoor unit includes: After the air conditioning system starts, close the control valve, and obtain the operating load and outer loop temperature of the indoor unit after the first preset time.

11. The air conditioning system oil return control method according to claim 7, characterized in that, The air conditioning system includes a plurality of parallel air conditioner outdoor unit systems; The step of controlling the opening or closing of the control valve according to the operating mode of the air conditioning system, the operating load, and the outer ring temperature includes: Controlling all the control valves of all the outdoor air conditioner systems to open or close simultaneously according to the operating mode of the air conditioning system, the operating load, and the outer ring temperature.

12. The oil return control method for an air conditioning system according to claim 7, characterized in that the outdoor air conditioner system further includes a temperature sensor disposed in the first pipeline to detect the temperature of the refrigerant in the first pipeline; the method further includes: obtaining the actual oil temperature in the first pipeline of each outdoor unit system through the temperature sensor disposed in the first pipeline; judging whether the actual oil temperature of each outdoor unit system is less than the corresponding target oil temperature; wherein, the target oil temperature characterizes the operating condition of the compressor in the outdoor unit system, and the target oil temperature corresponds to the compressor one by one; if the actual oil temperature of any outdoor unit system is less than the target oil temperature, controlling all the control valves to open, controlling the frequency of the compressor to increase, controlling the opening degree of the expansion valve to increase, and controlling the opening degree of the indoor expansion valve to increase, and maintaining for a first preset time.

13. The oil return control method for an air conditioning system according to claim 12, characterized in that the target oil temperature is calculated according to the following formula: T j = E * Td + B * Pd + C * Ps + D Among them, T j is the target oil temperature, Td is the exhaust gas temperature, Pd is the exhaust gas pressure, and Ps is the suction pressure; E, B, C, and D are constants, and E is j positively correlated with T, B is j negatively correlated with T, C is j positively correlated with T, and D is j positively correlated with T.

14. The oil return control method for an air conditioning system according to claim 11, characterized in that the step of controlling the frequency of the compressor to increase, controlling the opening degree of the expansion valve to increase, and controlling the opening degree of the indoor expansion valve to increase, and maintaining for a first preset time includes: controlling the frequency of the compressor to increase to 50% of the maximum operating frequency of the compressor, controlling the opening degree of the expansion valve to increase to 70% of the maximum opening degree, the opening degree of the indoor expansion valve to increase to 70% of the maximum opening degree, and maintaining the first preset time, the first preset time being greater than or equal to 3 minutes.

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