Outdoor unit system, air conditioning system and oil balancing control method thereof

Abstract

The embodiment of the invention provides an outdoor unit system, an air conditioning system and an oil balancing control method of the air conditioning system, and belongs to the field of air conditioners. An outlet of the compressor 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. 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, the first pipeline is provided with a temperature sensor, and the second pipeline is provided with a control valve. An oil return hole and an oil balancing hole are formed in a gas outlet pipe of the gas-liquid separator, and the oil balancing hole is higher than the oil return hole. Oil balancing can be achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of air conditioners, and in particular, to an outdoor unit system, an air conditioner system and an oil equalization control method thereof. Background Art

[0002] For a multi-connected air conditioner, a compressor is already 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 separator. This can improve the reliability of oil return and prevent liquid return. However, when the amount of oil entering the indoor unit is large, it will cause an increase in the heat exchange and pressure drop of the indoor unit evaporator, resulting in a decrease in performance, thereby reducing the performance of the whole machine. Moreover, in the case of multiple outdoor units connected in parallel, the excess oil in the outdoor unit is discharged into the indoor unit, and the oil balance of multiple outdoor units is achieved through the refrigerant distribution of the system. However, when the oil storage in the gas separator of a certain outdoor unit is too much and the excess oil in the gas separator cannot be discharged, it will cause the risk of oil imbalance, which will lead to a decrease in system output and affect the comfort of the experience. Summary of the Invention

[0003] The problem solved by the present invention is that when the oil storage in the gas separator is too much and the excess oil in the gas separator cannot be discharged, it will cause the risk of oil imbalance, affecting the system output and the comfort of use.

[0004] To solve the above problems, the present application provides an outdoor unit system, an air conditioner system and an oil equalization control method thereof, which can better achieve oil equalization to avoid oil shortage.

[0005] In a first aspect, the present invention provides an outdoor unit system, including 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;

[0006] 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;

[0007] 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;

[0008] 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;

[0009] 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;

[0010] One end of the first pipeline and the second pipeline are both connected to the oil discharge outlet of the oil separator. The other end of the first pipeline is communicated with the air inlet of the compressor. The other end of the second pipeline is communicated with the air inlet pipe of the gas-liquid separator. A temperature sensor is provided on the first pipeline, and a control valve is provided on the second pipeline;

[0011] An oil return hole and an oil equalizing hole are provided on the air outlet pipe of the gas-liquid separator, and the height of the oil equalizing hole is higher than that of the oil return hole.

[0012] In this application, by opening the control valve, the amount of oil entering the indoor unit can be reduced, the high pressure can be reduced, the low pressure can be increased, and the performance of the whole machine can be improved. Most importantly, by providing an oil equalizing hole in the gas-liquid separator, the excess oil in the gas-liquid separator is discharged through the oil equalizing hole to achieve oil equalizing balance, improve reliability, and prevent the risk of oil imbalance. The temperature sensor is used to detect whether the system lacks oil.

[0013] In an optional embodiment, the outdoor unit system further includes a first capillary tube and a second capillary tube;

[0014] The first capillary tube is arranged on the first pipeline, and the second capillary tube is arranged on the second pipeline.

[0015] In this application, by providing the first capillary tube and the second capillary tube, throttling can be achieved and better oil equalizing can be realized.

[0016] In an optional embodiment, the volume of the gas-liquid separator is A liters;

[0017] When the value range of A is between 0 and 10, the diameter value range of the oil equalizing hole is 1.5 mm - 2.5 mm, and the diameter value range of the oil return hole is 1 mm - 2 mm;

[0018] When the value range of A is between 10 and 20, the diameter value range of the oil equalizing hole is 2 mm - 3 mm, and the diameter value range of the oil return hole is 1.5 mm - 2.5 mm;

[0019] When the value range of A is between 20 and 30, the diameter value range of the oil equalizing hole is 2 mm - 3.5 mm, and the diameter value range of the oil return hole is 1.5 mm - 3 mm.

[0020] In an optional embodiment, the volume of the gas-liquid separator is A liters;

[0021] When the value range of A is between 0 and 10, the height value range of the oil equalizing hole from the bottom surface of the gas-liquid separator is 100 mm - 200 mm, and the height value range of the oil return hole from the bottom surface of the gas-liquid separator is 10 mm - 25 mm;

[0022] When the value range of A is between 10 and 20, the height of the oil equalizing hole from the bottom surface of the gas-liquid separator ranges from 150 mm to 250 mm, and the height of the oil return hole from the bottom surface of the gas-liquid separator ranges from 15 mm to 35 mm;

[0023] When the value range of A is between 20 and 30, the height of the oil equalizing hole from the bottom surface of the gas-liquid separator ranges from 150 mm to 300 mm, and the height of the oil return hole from the bottom surface of the gas-liquid separator ranges from 20 mm to 50 mm.

[0024] This application can better achieve oil equalization by setting the parameters of the oil equalizing hole and the oil return hole.

[0025] In a second aspect, the present invention provides an air conditioning system, including a plurality of outdoor unit systems described in any one of the foregoing embodiments;

[0026] The liquid valves and the gas valves of the plurality of outdoor unit systems are correspondingly connected in parallel through pipelines.

[0027] This application sets a plurality of parallel outdoor unit systems. When the temperature sensor detects that any one or more outdoor unit systems are short of oil, the corresponding control valve can be opened, and the control valves of other outdoor unit systems can be closed. In this way, the oil can be discharged into the indoor unit and enter the outdoor unit system with low oil temperature (i.e., short of oil) through the circulation of the refrigerant, realizing the balance of oil among the plurality of outdoor unit systems and the indoor unit.

[0028] In a third aspect, the present invention provides an oil equalization control method for an air conditioning system, which is applied to the air conditioning system described in the foregoing embodiments. The method includes:

[0029] Obtain the actual oil temperature in the first pipeline of each outdoor unit system through the temperature sensor arranged in the first pipeline;

[0030] Judge 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;

[0031] If the actual oil temperature of some of the outdoor unit systems is less than the target oil temperature, control the control valve of the corresponding outdoor unit system to open;

[0032] If the actual oil temperature of some of the outdoor unit systems is greater than or equal to the target oil temperature, control the control valve of the corresponding outdoor unit system to close.

[0033] In this application, by setting up multiple parallel outdoor unit systems, when the oil shortage in any one or more outdoor unit systems is detected by a temperature sensor, the corresponding control valve can be opened, while the control valves of other outdoor unit systems are closed. In this way, the oil can be discharged into the indoor unit and enter the outdoor unit system with a low oil temperature (i.e., oil shortage) through the circulation of the refrigerant, so as to achieve the balance of oil among multiple outdoor unit systems and the indoor unit.

[0034] In an alternative embodiment, the target oil temperature is calculated according to the following formula:

[0035] Tj = E * Td + B * Pd + C * Ps + D

[0036] where Tj is the target oil temperature, Td is the exhaust gas temperature, Pd is the exhaust gas pressure, and Ps is the suction pressure;

[0037] 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.

[0038] Through the above calculation formula, the target oil temperature can be accurately determined, so that the control is more accurate.

[0039] In an alternative embodiment, in the cooling mode of the air-conditioning system, 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;

[0040] In the heating mode of the air-conditioning system, 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.

[0041] Since the outer ring temperature in the cooling mode is higher than that in the heating mode, the oil temperature drops more slowly in the cooling mode. When cooling, E is [5, 10], when heating, E is [1, 5], when cooling, B is [-3, -1], when heating, B is [-5, -3], when cooling, C is [3, 5], and when heating, C is [1, 3]. In this way, better control can be achieved.

[0042] In an alternative embodiment, the air-conditioning system further includes multiple parallel indoor units and indoor expansion valves correspondingly connected to the indoor units;

[0043] The method further includes:

[0044] If the actual oil temperatures of all the outdoor unit systems are less than the target oil temperature, then increase the compressor frequency of all the outdoor unit systems, and increase the opening degree of the expansion valve and the opening degree of the indoor expansion valve.

[0045] When it is detected that all the outdoor units are short of oil, through the above control method, the oil stored in the indoor unit can quickly return to multiple outdoor unit systems to achieve oil equalization.

[0046] In an alternative embodiment, the steps of controlling the compressor frequency of all the outdoor unit systems to increase, controlling the opening degree of the expansion valve to increase, and controlling the opening degree of the indoor expansion valve to increase include:

[0047] Control the compressor frequency of all the outdoor unit systems to increase to 50% of the maximum operating frequency of the compressor, 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 to increase to 70% of the maximum opening degree, and end after running for a first preset time. This can achieve rapid and uniform oil return. Description of the Drawings

[0048] Figure 1 It is a schematic structural diagram of the outdoor unit system provided by the embodiment of the present invention;

[0049] Figure 2 It is a schematic structural diagram of the air-conditioning system provided by the embodiment of the present invention.

[0050] Description of the Reference Numerals

[0051] Description of the Reference Numerals: 100 - air-conditioning system; 1 - outdoor unit system; 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; 12 - oil equalization 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

[0052] In the case of multiple parallel outdoor units, the excess oil of the outdoor units is discharged into the indoor unit, and the oil balance of multiple outdoor units is achieved through the refrigerant distribution of the system. However, when the oil storage in the gas-liquid separator of a certain outdoor unit is too much and the excess oil in the gas-liquid separator cannot be discharged, it will lead to the risk of oil imbalance, which will cause problems such as reduced system output and affecting the comfort of the experience. The embodiment of the present invention provides an outdoor unit system, an air-conditioning system and an oil equalization control method thereof. It can achieve oil equalization between multiple outdoor units and between the outdoor unit and the indoor unit.

[0053] 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.

[0054] Please refer to Figure 1 and Figure 2, in this embodiment, the air conditioning system 100 includes an outdoor unit system 1. 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, a gas valve 18, and a liquid valve 17. 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 is connected to the liquid valve 17, and the fourth interface of the four-way valve 4 is connected to the gas valve 18. 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 air 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 temperature sensor 23 is provided on the first pipe 8, and a control valve 10 is provided on the second pipe 9. An oil return hole 11 and an oil equalizing hole 12 are provided on the outlet pipe of the gas-liquid separator 5, and the installation height of the oil equalizing hole 12 is higher than that of the oil return hole 11.

[0055] In this embodiment, the temperature sensor 23 is provided to detect the oil quantity through the oil temperature interval. By setting the control valve 10, when multiple outdoor unit systems 1 are connected in parallel as the outdoor unit, the oil can be evenly distributed among multiple outdoor unit systems 1 and between the outdoor unit system 1 and the indoor unit by controlling the state of the control valve 10. Most importantly, by providing the oil equalizing hole 12 in the gas-liquid separator 5, the excess oil in the gas-liquid separator 5 is discharged through the oil equalizing hole 12 to achieve oil equalizing balance, improve reliability, and prevent the risk of oil imbalance.

[0056] It should be noted that the oil return hole 11 and the oil equalizing hole 12 in this application are on the section of the outlet pipe inside the gas-liquid separator.

[0057] 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.

[0058] In this embodiment, by providing the first capillary tube 13 and the second capillary tube 14, throttling can be achieved to better evenly distribute the oil.

[0059] Please refer to Figure 1 and Figure 2, 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 equalizing hole 12 is 1.5 mm - 2.5 mm, and 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 equalizing hole 12 is 2 mm - 3 mm, and 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 equalizing hole 12 is 2 mm - 3.5 mm, and 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 equalizing hole 12 from the bottom surface of the gas-liquid separator 5 is 100 mm - 200 mm, and 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 equalizing hole 12 from the bottom surface of the gas-liquid separator 5 is 150 mm - 250 mm, and 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 equalizing hole 12 from the bottom surface of the gas-liquid separator 5 is 150 mm - 300 mm, and 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. The bottom surface of the gas-liquid separator 5 refers to the bottom surface inside the gas-liquid separator 5.

[0060] In this embodiment, by setting the parameters of the oil equalizing hole 12 and the oil return hole 11, better oil equalization can be achieved on-site and the problem of uneven oil can be avoided.

[0061] In this embodiment, the control valve 10 is a solenoid valve, which can be conveniently controlled.

[0062] In this embodiment, the outdoor unit system 1 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 far 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 far from the heat exchanger, and a subcooling expansion valve 16 is provided. The outlet side of this heat exchange pipeline is connected to the inlet of the liquid separator of the gas-liquid separator 5 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.

[0063] In this embodiment, the air conditioning system 100 further includes a plurality of outdoor unit systems 1, a plurality of parallel indoor units 21, and an indoor expansion valve 22 correspondingly connected to the indoor unit 21. The plurality of outdoor unit systems 1 are connected in parallel to form an outdoor unit, and are connected in series with the plurality of parallel indoor units 21, thereby forming a refrigerant circulation loop. The indoor expansion valve 7 correspondingly connected to the indoor unit 21 is used to control whether the indoor unit 21 is connected to the refrigerant circulation system.

[0064] The air conditioning system 100 provided in this embodiment obtains the actual oil temperature in a first pipeline of each outdoor unit system 1 through the temperature sensor 23 provided in the first pipeline 8 of each outdoor unit system 1. And compare the actual oil temperature with the corresponding target oil temperature. If the actual oil temperature of some outdoor unit systems 1 is less than the target oil temperature, the control valve 10 of the corresponding outdoor unit system 1 is opened. If the actual oil temperature of some outdoor unit systems 1 is greater than or equal to the target oil temperature, the control valve 10 of the corresponding outdoor unit system 1 is closed. In this way, oil equalization between multiple outdoor unit systems 1 can be achieved. And when the actual oil temperature of all outdoor unit systems 1 is less than the target oil temperature, all control valves 10 are opened in this way, which can reduce the amount of oil entering.

[0065] For example, when there are four outdoor unit systems 1 connected in parallel and two of them are short of oil, keep all compressors 2 running at the current frequency, open the control valves 10 of the two outdoor unit systems 1 that are short of oil, and close the control valves 10 of the two outdoor unit systems 1 that are not short of oil for oil equalization operation. When it is detected that the oil in a certain outdoor unit system 1 that is short of oil is normal (i.e., the oil temperature is normal), close the control valve 10 of this outdoor unit system 1. Until the oil in the last outdoor unit system 1 is normal, all control valves 10 of all outdoor unit systems 1 are closed, and re-judgment control is performed.

[0066] Please refer to Figure 1 and Figure 2 For the air conditioning system 100 provided in the above embodiment, this embodiment further provides an oil equalization control method for the air conditioning system 100, which is applied to the air conditioning system 100 in the foregoing embodiment to achieve better oil equalization.

[0067] The method includes:

[0068] S1. Obtain the actual oil temperature in the first pipeline 8 of each outdoor unit system 1 through the temperature sensor 23 provided in the first pipeline 8;

[0069] S3. Judge whether the actual oil temperature of each outdoor unit system 1 is less than the corresponding target oil temperature; wherein, the target oil temperature represents the operating condition of the compressor 2 in the outdoor unit system 1, and the target oil temperature corresponds to the compressor 2 one by one;

[0070] S5. If the actual oil temperature of some outdoor unit systems 1 is less than the target oil temperature, control the control valve 10 of the corresponding outdoor unit system 1 to open;

[0071] S7. If the actual oil temperature of part of the outdoor unit system 1 is greater than or equal to the target oil temperature, then control the control valve 10 of the corresponding outdoor unit system 1 to close.

[0072] In this embodiment, by providing a plurality of parallel outdoor unit systems 1, when the temperature sensor 23 detects that any one or more of the outdoor unit systems 1 are short of oil, the corresponding control valve 10 can be opened, while the control valves 10 of the other outdoor unit systems 1 are closed. In this way, the oil can be discharged into the indoor unit 21 and enter the outdoor unit system 1 with a low oil temperature (i.e., short of oil) through the circulation of the refrigerant, realizing the balance of oil among the plurality of outdoor unit systems 1 and the indoor unit 21.

[0073] It should be noted that the frequency of the compressor remains unchanged in steps S5 and S7.

[0074] In this embodiment, the target oil temperature is calculated according to the following formula:

[0075] Tj = E * Td + B * Pd + C * Ps + D

[0076] Wherein, Tj is the target oil temperature, Td is the exhaust gas temperature, Pd is the exhaust gas pressure, and Ps is the suction pressure;

[0077] 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.

[0078] Through the above calculation formula, the target oil temperature can be accurately determined, thus making the control more accurate.

[0079] It should be noted that D is a correction parameter and can be determined according to characteristics such as the model of the compressor 2.

[0080] 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;

[0081] 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.

[0082] Since the outer ring temperature in the refrigeration mode is higher than that in the heating mode, the oil temperature drops more slowly in the refrigeration mode. When refrigerating, A is [5, 10], when heating, A is [1, 5], when refrigerating, B is [-3, -1], when heating, B is [-5, -3], when refrigerating, C is [3, 5], and when heating, C is [1, 3]. In this way, better control can be achieved.

[0083] In this embodiment, the method further includes:

[0084] S9. If the actual oil temperature of all the outdoor unit systems 1 is less than the target oil temperature, then control the frequency of the compressors 2 of all the outdoor unit systems 1 to increase, and control the opening degree of the expansion valves 7 to increase, and control the opening degree of the indoor expansion valve 22 to increase.

[0085] In this embodiment, when it is detected that all the outdoor unit systems 1 are short of oil, through the above control method, the oil stored in the indoor unit 21 can be quickly returned to the multiple outdoor unit systems 1 to achieve oil equalization.

[0086] In this embodiment, step S9 includes:

[0087] S9. If the actual oil temperature of all the outdoor unit systems 1 is less than the target oil temperature, then control the frequency of the compressors 2 of all the outdoor unit systems 1 to increase to 50% of the maximum operating frequency of the compressors 2, the opening degree of the expansion valves 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 end after running for a first preset time.

[0088] This can quickly return the oil stored in the indoor unit 21 to the outdoor unit systems 1 and then perform oil equalization.

[0089] In summary, the working principles and beneficial effects of the outdoor unit system 1, the system and its oil equalization control method provided by the embodiments of the present invention include:

[0090] The air conditioning system 100 provided by this embodiment obtains the actual oil temperature in a pipeline of each outdoor unit system 1 through the temperature sensor 23 provided in the first pipeline 8 of each outdoor unit system 1. And compare the actual oil temperature with the corresponding target oil temperature. If the actual oil temperature of some outdoor unit systems 1 is less than the target oil temperature, then open the control valve 10 of the corresponding outdoor unit system 1. If the actual oil temperature of some outdoor unit systems 1 is greater than or equal to the target oil temperature, then close the control valve 10 of the corresponding outdoor unit system 1. This can achieve oil equalization among multiple outdoor unit systems 1. And when the actual oil temperature of all the outdoor unit systems 1 is less than the target oil temperature, opening all the control valves 10 in this way can reduce the amount of oil entering the interior.

[0091] 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, 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 ends of the first pipe and the second pipe are both 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 temperature sensor is arranged on the first pipe, and a control valve is arranged on the second pipe; An oil return hole and an oil equalizing hole are arranged on the outlet pipe of the gas-liquid separator, and the height of the oil equalizing hole is higher than the height of the oil return hole.

2. The outdoor unit system according to claim 1, characterized in that, the outdoor unit system 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 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 equalizing hole is 1.5 mm - 2.5 mm, and the diameter value range of the oil return hole is 1 mm - 2 mm; When the value range of A is between 10 and 20, the diameter value range of the oil equalizing hole is 2 mm - 3 mm, and the diameter value range of the oil return hole 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 equalizing hole is 2 mm - 3.5 mm, and the diameter value range of the oil return hole is 1.5 mm - 3 mm.

4. The outdoor unit system 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 value range of the height of the oil equalizing hole from the bottom surface of the gas-liquid separator is 100 mm - 200 mm, and the value range of the height of the oil return hole from the bottom surface of the gas-liquid separator is 10 mm - 25 mm; When the value range of A is between 10 and 20, the value range of the height of the oil equalizing hole from the bottom surface of the gas-liquid separator is 150 mm - 250 mm, and the value range of the height of the oil return hole from the bottom surface of the gas-liquid separator is 15 mm - 35 mm; When the value range of A is between 20 and 30, the value range of the height of the oil equalizing hole from the bottom surface of the gas-liquid separator is 150 mm - 300 mm, and the value range of the height of the oil return hole from the bottom surface of the gas-liquid separator is 20 mm - 50 mm.

5. An air conditioning system, It is characterized in that it includes a plurality of outdoor unit systems described in any one of claims 1-4; the liquid valves and the gas valves of the plurality of outdoor unit systems are correspondingly connected in parallel through pipelines.

6. An oil equalization control method for an air conditioning system, it is characterized in that it is applied to the air conditioning system described in claim 5, and the method includes: obtaining the actual oil temperature in the first pipeline of each outdoor unit system through the temperature sensor arranged 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 some of the outdoor unit systems is less than the target oil temperature, controlling the control valve of the corresponding outdoor unit system to open; if the actual oil temperature of some of the outdoor unit systems is greater than or equal to the target oil temperature, controlling the control valve of the corresponding outdoor unit system to close.

7. The oil equalization control method for an air conditioning system according to claim 6, it is 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.

8. The oil equalization control method for an air conditioning system according to claim 7, it is characterized in that in the cooling mode of the air conditioning system, 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, 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.

9. The oil equalization control method for an air conditioning system according to claim 6, it is characterized in that the air conditioning system further includes a plurality of indoor units connected in parallel and indoor expansion valves correspondingly connected to the indoor units; the method further includes: if the actual oil temperatures of all the outdoor unit systems are less than the target oil temperature, controlling the compressor frequency of all the outdoor unit systems to increase, and controlling the opening degree of the expansion valve to increase, and controlling the opening degree of the indoor expansion valve to increase.

10. The oil equalization control method for an air conditioning system according to claim 9, it is characterized in that the steps of controlling the compressor frequency of all the outdoor unit systems to increase, and controlling the opening degree of the expansion valve to increase, and controlling the opening degree of the indoor expansion valve to increase include: controlling the compressor frequency of all the outdoor unit systems to increase to 50% of the maximum operating frequency of the compressor, 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 to increase to 70% of the maximum opening degree.

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