An air conditioner and its control method

Abstract

The present invention discloses an air conditioner and its control method. An oil return control device is added on the exhaust side of the compressor to reduce the lubricating oil content in the condenser; an oil outlet is added at the bottom of the compressor, and an oil discharging control device is added on the path of this oil outlet to supply a small part of the oil at the bottom of the compressor to the inlet of the evaporator. Based on the detected oil content in the refrigerant, the opening and closing states of the oil discharging control device and the oil return control device are controlled, so that the oil content in the refrigerant is within an ideal range. By adopting the embodiment of the present invention, the mass ratio of the lubricating oil to the refrigerant in the condenser can be reduced, and the mass ratio of the lubricating oil to the refrigerant in the evaporator can be between an optimal range, so that the heat exchange performance of both the condenser and the evaporator reaches the best state.

Description

Technical Field

[0001] The present invention relates to the technical field of air conditioners, and particularly to an air conditioner and a control method thereof. Background Art

[0002] During the operation of the compressor in an air conditioner, a small part of lubricating oil is carried in the discharged refrigerant. The refrigerant with lubricating oil will affect the performance after passing through the condenser and the evaporator. For the condenser, even if it contains a small amount of lubricating oil, such as when the mass ratio of the lubricating oil to the refrigerant reaches about 0.5%, the compressor power will increase, resulting in a decrease in energy efficiency. Therefore, it is necessary to control the lubricating oil content in the condenser not to be too high. For the evaporator, a small amount of lubricating oil can increase the surface tension of the refrigerant, thereby changing its surface wettability to the pipe wall. However, when there is too much lubricating oil, the lubricating oil will affect the formation of bubbles during the boiling of the refrigerant, reducing the generation speed and frequency of bubbles, increasing the pressure drop and thermal resistance, and thus reducing the heat exchange effect. Therefore, it is necessary to control the lubricating oil content in the evaporator within an appropriate range.

[0003] Existing air conditioners usually add an oil return control device on the exhaust side of the compressor to control the oil content of the refrigerant. However, this oil return device can only control the simultaneous decrease in the mass ratio of the lubricating oil to the refrigerant in the condenser and the evaporator, and cannot control the increase in the mass ratio of the lubricating oil to the refrigerant in the evaporator. Therefore, the heat exchange performance of the evaporator cannot be improved. Summary of the Invention

[0004] The purpose of the embodiments of the present invention is to provide an air conditioner and a control method thereof, which can not only reduce the mass ratio of the lubricating oil to the refrigerant in the condenser, but also simultaneously adjust the mass ratio of the lubricating oil to the refrigerant in the evaporator within an optimal performance range.

[0005] To achieve the above purpose, the embodiments of the present invention provide an air conditioner, including:

[0006] An indoor unit for adjusting the indoor temperature and / or humidity, and an indoor heat exchanger is provided in the indoor unit;

[0007] An outdoor unit is connected to the indoor unit through a connection pipe. The outdoor unit is used to provide power for the refrigeration cycle. A compressor and an outdoor heat exchanger are provided in the outdoor unit. The compressor, the outdoor heat exchanger and the indoor heat exchanger form a refrigerant circuit through pipelines; an air suction port, an exhaust port and an oil outlet for discharging the lubricating oil inside the compressor are provided on the compressor;

[0008] An oil discharging control device is provided in the outdoor unit, one end is connected to the oil outlet of the compressor, and the other end is communicated with the indoor heat exchanger or the outdoor heat exchanger. When the oil discharging control device is opened, the oil of the compressor is discharged into the pipeline to be mixed with the refrigerant;

[0009] An oil-gas separator is provided in the outdoor unit. An inlet, an outlet and an oil outlet are provided on the oil-gas separator. Wherein, the inlet is connected to the exhaust port of the compressor, and the outlet communicates with the indoor heat exchanger or the outdoor heat exchanger;

[0010] An oil return control device is provided in the outdoor unit. One end is connected to the oil outlet of the oil-gas separator, and the other end is connected to the suction port of the compressor. When the oil return control device is opened, the oil separated in the oil-gas separator is discharged into the compressor;

[0011] The controller is configured to:

[0012] In response to the start operation of the air conditioner, control the oil return control device and the oil discharge control device to be in the closed state;

[0013] Obtain the oil content in the refrigerant;

[0014] Compare the oil content with a preset oil content range, and adjust the opening and closing states of the oil return control device and the oil discharge control device according to the comparison result, so as to adjust the oil content in the refrigerant to be within a preset saturation range; wherein, the oil content range includes a low concentration range, a saturation concentration range and a high concentration range.

[0015] As an improvement of the above solution, when the air conditioner is a heating and cooling air conditioner, the controller is further configured to:

[0016] When the air conditioner enters the cooling mode, control the two ends of the oil discharge control device to be respectively connected to the oil outlet of the compressor and the indoor heat exchanger, and control the outlet of the oil-gas separator to be connected to the outdoor heat exchanger;

[0017] When the air conditioner enters the heating mode, control the two ends of the oil discharge control device to be respectively connected to the oil outlet of the compressor and the outdoor heat exchanger, and control the outlet of the oil-gas separator to be connected to the indoor heat exchanger.

[0018] As an improvement of the above solution, when the air conditioner is a single-cooling air conditioner, the controller is further configured to:

[0019] Control the two ends of the oil discharge control device to be respectively connected to the oil outlet of the compressor and the indoor heat exchanger, and control the outlet of the oil-gas separator to be connected to the outdoor heat exchanger.

[0020] As an improvement of the above solution, when the oil content is within the saturation concentration range, the controller is further configured to:

[0021] Control the oil return control device and the oil discharge control device to be in the closed state.

[0022] As an improvement to the above solution, when the oil content is within the high-concentration range, the controller is configured to:

[0023] Control the oil discharge control device to remain closed;

[0024] Adjust the valve opening of the oil return control device, and when it is detected that the oil content is less than a preset oil quantity threshold, keep the current valve opening of the oil return control device unchanged;

[0025] Adjust the valve opening of the oil discharge control device so that the oil content is within the saturation concentration range.

[0026] As an improvement to the above solution, the controller is configured to:

[0027] Control the oil return control device to remain closed;

[0028] Adjust the valve opening of the oil return control device so that the oil content is within the saturation concentration range.

[0029] To achieve the above object, an embodiment of the present invention further provides an air conditioner control method. An air conditioner compressor is provided with a suction port, a discharge port, and an oil outlet for discharging the lubricating oil inside the compressor; an oil discharge control device, an oil-gas separator, and an oil return control device are provided in the air conditioner. One end of the oil discharge control device is connected to the oil outlet of the compressor, and the other end communicates with an indoor heat exchanger or an outdoor heat exchanger. When the oil discharge control device is opened, the oil of the compressor is discharged into the pipeline to be mixed with the refrigerant; the oil-gas separator is provided with an inlet, an outlet, and an oil outlet. The inlet is connected to the discharge port of the compressor, and the outlet communicates with an indoor heat exchanger or an outdoor heat exchanger; one end of the oil return control device is connected to the oil outlet of the oil-gas separator, and the other end is connected to the suction port of the compressor. When the oil return control device is opened, the oil separated in the oil-gas separator is discharged into the compressor. Then, the air conditioner control method includes:

[0030] In response to the air conditioner startup operation, control the oil return control device and the oil discharge control device to be in a closed state;

[0031] Obtain the oil content in the refrigerant;

[0032] Compare the oil content with a preset oil quantity range, and adjust the opening and closing states of the oil return control device and the oil discharge control device according to the comparison result to adjust the oil content in the refrigerant to be within a preset saturation range; wherein, the oil quantity range includes a low-concentration range, a saturation concentration range, and a high-concentration range.

[0033] As an improvement to the above solution, when the oil content is within the saturation concentration range, the control mode is:

[0034] Control the oil return control device and the oil discharge control device to be in the closed state.

[0035] As an improvement to the above solution, when the oil content is within the high concentration range, the control mode is:

[0036] Control the oil discharge control device to remain closed;

[0037] Adjust the valve opening of the oil return control device, and when it is detected that the oil content is less than a preset oil quantity threshold, keep the current valve opening of the oil return control device unchanged;

[0038] Adjust the valve opening of the oil discharge control device so that the oil content is within the saturated concentration range.

[0039] As an improvement to the above solution, when the oil content is within the low concentration range, the control mode is:

[0040] Control the oil return control device to remain closed;

[0041] Adjust the valve opening of the oil return control device so that the oil content is within the saturated concentration range.

[0042] Compared with the prior art, for the air conditioner and its control method disclosed in the present invention, an oil return control device is added on the exhaust side of the compressor to reduce the lubricating oil content in the condenser; an oil outlet is added at the bottom of the compressor (lubricating oil is usually filled at the bottom of the compressor for lubricating the moving parts of the compressor), and an oil discharge control device is added on the path of this oil outlet to supply a small part of the oil at the bottom of the compressor to the inlet of the evaporator. Based on the detected oil content in the refrigerant, the operation modes of the oil discharge control device and the oil return control device are controlled, so that the oil content in the refrigerant is within an ideal range. By adopting the embodiments of the present invention, not only can the mass ratio of the lubricating oil to the refrigerant in the condenser be reduced, but also the mass ratio of the lubricating oil to the refrigerant in the evaporator can be between an optimal range, so that the heat exchange performance of both the condenser and the evaporator reaches the best state. Description of the Drawings

[0043] Figure 1 is a schematic diagram of the external structure of an air conditioner provided by an embodiment of the present invention;

[0044] Figure 2 is a schematic diagram of the structure of the refrigeration system in a cooling and heating air conditioner provided by an embodiment of the present invention;

[0045] Figure 3 is a refrigerant flow diagram when the cooling and heating air conditioner provided by an embodiment of the present invention operates in the refrigeration mode;

[0046] Figure 4It is a refrigerant flow diagram when the heating and cooling air conditioner provided by the embodiment of the present invention operates in the heating mode;

[0047] Figure 5 It is a refrigerant flow diagram when the single-cooling air conditioner provided by the embodiment of the present invention operates in the cooling mode;

[0048] Figure 6 It is the first working flow chart of the controller in the air conditioner provided by the embodiment of the present invention;

[0049] Figure 7 It is the second working flow chart of the controller in the air conditioner provided by the embodiment of the present invention;

[0050] Figure 8 It is the third working flow chart of the controller in the air conditioner provided by the embodiment of the present invention;

[0051] Figure 9 It is the fourth working flow chart of the controller in the air conditioner provided by the embodiment of the present invention;

[0052] Figure 10 It is the flow chart of a method for controlling an air conditioner provided by the embodiment of the present invention.

[0053] Among them, 100 is the indoor unit; 200 is the outdoor unit; 10 is the compressor; 10a is the exhaust port of the compressor; 10b is the suction port of the compressor; 10c is the oil outlet of the compressor; 11 is the outdoor heat exchanger; 12 is the indoor heat exchanger; 13 is the four-way valve; 14 is the oil-gas separator; 14a is the inlet of the oil-gas separator; 14b is the outlet of the oil-gas separator; 14c is the oil outlet of the oil-gas separator; 15 is the oil return control device; 16 is the oil discharge control device; 17 is the oil quantity detection device; 18 is the throttling device. Detailed implementation manners

[0054] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making creative efforts shall fall within the protection scope of the present invention.

[0055] In the description of the present application, it should be understood that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and 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.

[0056] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of this application, unless otherwise specified, the meaning of "a plurality" is two or more.

[0057] In the description of this application, it should be noted that unless otherwise clearly defined and limited, the terms "installed", "connected", and "coupled" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0058] See Figure 1 , Figure 1 is a schematic diagram of the external structure of an air conditioner provided by an embodiment of the present invention. The air conditioner described in the embodiment of the present invention includes an indoor unit 100 and an outdoor unit 200. The indoor unit 100 is used to adjust the temperature and humidity of indoor air. The outdoor unit 200 is connected to the indoor unit 100 through a connection pipe. The outdoor unit 200 is installed outdoors, and the indoor unit 100 is installed indoors. The outdoor unit 200 is used to provide the power for the refrigeration cycle. A compressor and an outdoor heat exchanger are provided in the outdoor unit 200. The compressor, the outdoor heat exchanger, and the indoor heat exchanger form a refrigerant circuit through pipelines. In the embodiment of the present invention, the method for controlling the oil content of the refrigerant can be applied to a heating and cooling air conditioner or a single-cooling air conditioner. Among them, the heating and cooling air conditioner is an air conditioner with both refrigeration and heating functions, and the single-cooling air conditioner is an air conditioner with only refrigeration function.

[0059] In the embodiment of the present invention, improvements are made to the compressor of a traditional air conditioner. In addition to the common suction port and discharge port, an oil outlet is added at the bottom of the compressor. Since the lubricating oil is filled at the bottom of the compressor to lubricate the moving parts of the compressor, the oil outlet can discharge the lubricating oil of the compressor. In addition, in the embodiment of the present invention, an oil discharge control device, an oil-gas separator and an oil return control device are additionally provided in the outdoor unit 200. The oil discharge control device can be a flow control device such as an electronic expansion valve for adjusting the flow rate. The oil discharge control device is a three-way valve. The first end of the oil discharge control device is connected to the oil outlet of the compressor, the second end is connected to the indoor heat exchanger, and the third end is connected to the outdoor heat exchanger. By controlling the opening / closing of the three ports, the oil discharge control device is connected to the outdoor heat exchanger or the indoor heat exchanger, and when the oil discharge control device is opened, the oil of the compressor is discharged into the pipeline to be mixed with the refrigerant. The oil-gas separator is provided with an inlet, an outlet and an oil outlet. The inlet is connected to the discharge port of the compressor, and the outlet is connected to the indoor heat exchanger or the outdoor heat exchanger. The oil return control device can be a flow control device such as an electronic expansion valve for adjusting the flow rate. The oil return control device is a two-way valve. One end of the oil return control device is connected to the oil outlet of the oil-gas separator, and the other end is connected to the suction port of the compressor. When the oil return control device is opened, the oil separated in the oil-gas separator is discharged into the compressor.

[0060] See Figure 2 , Figure 2It is a schematic structural diagram of a refrigeration system in a heating and cooling air conditioner provided by an embodiment of the present invention. The air conditioner includes a compressor 10, an outdoor heat exchanger 11, an indoor heat exchanger 12, a four-way valve 13, an oil-gas separator 14, an oil return control device 15, an oil discharge control device 16, an oil quantity detection device 17, and a throttling device 18. An exhaust port 10a, a suction port 10b, and an oil outlet 10c are provided in the compressor 10. A D pipe, a C pipe, an S pipe, and an E pipe are provided on the four-way valve 13. An inlet 14a, an outlet 14b, and an oil outlet 14c are provided on the oil-gas separator 14. The exhaust port 10a of the compressor 10 is connected to the inlet 14a of the oil-gas separator 14, the outlet 14b of the oil-gas separator 14 is connected to the D pipe of the four-way valve 13, the C pipe of the four-way valve 13 is connected to the outdoor heat exchanger 11, the outdoor heat exchanger 11 is connected to the throttling device 18, the throttling device 18 is connected to the indoor heat exchanger 12, the indoor heat exchanger 12 is connected to the E pipe of the four-way valve 13, the S pipe of the four-way valve 13 is connected to the suction port 10b of the compressor 10, the oil outlet 10c of the compressor 10 is connected to the oil discharge control device 16, the oil discharge control device 16 communicates with the outdoor heat exchanger 11 or the indoor heat exchanger 12, the oil outlet 14c of the oil-gas separator 14 is connected to the oil return control device 15, the oil return control device 15 is connected to the suction port 10b of the compressor 10, the oil quantity detection device 17 is arranged in the pipeline where the S pipe of the four-way valve 13 communicates with the suction port 10b of the compressor 10, and the oil quantity detection device 17 can calculate the oil discharge amount by detecting flow rate, density, pressure, viscosity, temperature or other parameters. An existing oil quantity detection device can be adopted, which will not be elaborated here.

[0061] The heating and cooling air conditioner described in the embodiment of the present invention includes a refrigeration mode and a heating mode. When refrigerating and heating, the flow direction of the refrigerant is different. When refrigerating, the refrigerant first flows through the outdoor unit heat exchanger. At this time, the outdoor unit is a condenser and the indoor unit is an evaporator. When heating, the refrigerant first flows through the indoor unit heat exchanger. At this time, the indoor unit is a condenser and the outdoor unit is an evaporator. In different states of refrigerating and heating, the air conditioner will change the flow direction of the refrigerant through the four-way valve. Without the four-way valve, the air conditioner can only achieve single refrigeration or heating and cannot switch between cooling and heating.

[0062] See Figure 3 , Figure 3It is the refrigerant flow diagram when the cooling and heating air conditioner provided by the embodiment of the present invention operates in the cooling mode. At this time, the D pipe and the C pipe of the four-way valve 13 are connected, and the S pipe and the E pipe are connected to realize that the outlet 14b of the oil-gas separator 14 is connected to the outdoor heat exchanger 11. The oil discharge control device 16 is connected to the indoor heat exchanger 12 (evaporator), and the oil discharge control device 16 discharges the lubricating oil discharged from the compressor 10 into the indoor heat exchanger 12 (evaporator). At this time, when operating in cooling, the refrigerant circuit satisfies that the refrigerant first passes through the compressor 10 to become high-pressure gas. The refrigerant discharged from the compressor 10 enters the inlet 14a of the oil-gas separator 14. In the oil-gas separator 14, liquid oil and gaseous refrigerant are separated. The liquid oil is heavier and sinks to the bottom of the oil-gas separator 14, and returns to the compressor 10 through the oil outlet 14c of the oil-gas separator 14, the oil return control device 15, and the suction port 10b of the compressor 10. The gaseous refrigerant is lighter, and then enters the D pipe and the C pipe of the four-way valve 13 through the upper outlet 14b of the oil-gas separator 14 and flows into the outdoor heat exchanger 11 (condenser). Then, it passes through the throttling device 18, the indoor heat exchanger 12 (evaporator), the E pipe of the four-way valve 13, the S pipe of the four-way valve 13, and then the oil content of the refrigerant is detected by the oil content detection device 17, and then is incorporated into the compressor through the suction port 10b of the compressor 10. In addition, the oil at the oil outlet 10c of the compressor 10 enters the inlet of the indoor heat exchanger 12 (evaporator) through the oil discharge control device 16.

[0063] See Figure 4 , Figure 4It is a refrigerant flow diagram when the heating and cooling air conditioner provided by the embodiment of the present invention operates in the heating mode. At this time, the D pipe and the E pipe of the four-way valve 13 are connected, and the C pipe and the S pipe are connected, so that the outlet 14b of the oil-gas separator 14 is connected to the indoor heat exchanger 12, and the oil discharge control device 16 is connected to the outdoor heat exchanger 11 (evaporator). The oil discharge control device 16 discharges the lubricating oil discharged from the compressor 10 into the outdoor heat exchanger 11 (evaporator). At this time, when operating in heating, the refrigerant circuit satisfies that the refrigerant first passes through the compressor 10 to become high-pressure gas. The refrigerant discharged from the compressor 10 enters the inlet 14a of the oil-gas separator 14. In the oil-gas separator 14, liquid oil and gaseous refrigerant are separated. The liquid oil is heavier and sinks to the bottom of the oil-gas separator 14, and returns to the compressor 10 through the oil outlet 14c of the oil-gas separator 14, the oil return control device 15, and the suction port 10b of the compressor 10. The gaseous refrigerant is lighter, and then enters the D pipe and the E pipe of the four-way valve 13 through the upper outlet 14b of the oil-gas separator 14, flows into the indoor heat exchanger 12 (condenser), then passes through the throttling device 18, the outdoor heat exchanger 11 (evaporator), the C pipe of the four-way valve 13, the S pipe of the four-way valve 13, and then the oil content of the refrigerant is detected by the oil quantity detection device 17, and then converges into the compressor through the suction port 10b of the compressor 10. In addition, the oil at the oil outlet 10c of the compressor 10 enters the inlet of the outdoor heat exchanger 11 (evaporator) through the oil discharge control device 16.

[0064] See Figure 5 , Figure 5It is the refrigerant flow diagram when the single-cool air conditioner provided by the embodiment of the present invention operates in the cooling mode. At this time, there is no need for a four-way valve in the air conditioner. The oil quantity detection device 17 is arranged between the channels of the indoor heat exchanger 12 and the suction port 10b of the compressor 10. The oil discharge control device 16 is connected to the indoor heat exchanger 12, and the outlet 14b of the oil-gas separator 14 is connected to the outdoor heat exchanger 11. At this time, when operating in cooling, the refrigerant circuit satisfies: the refrigerant first passes through the compressor 10 to become high-pressure gas. The refrigerant discharged from the compressor 10 enters the inlet 14a of the oil-gas separator 14. In the oil-gas separator 14, liquid oil and gaseous refrigerant are separated. The liquid oil is heavier and sinks to the bottom of the oil-gas separator 14, and returns to the compressor 10 through the oil outlet 14c of the oil-gas separator 14, the oil return control device 15, and the suction port 10b of the compressor 10. The gaseous refrigerant is lighter, and then flows into the outdoor heat exchanger 11 (condenser) through the upper outlet 14b of the oil-gas separator 14, and then passes through the throttling device 18 and the indoor heat exchanger 12 (evaporator). After that, the oil quantity detection device 17 detects the oil content of the refrigerant, and then converges into the compressor through the suction port 10b of the compressor 10. In addition, the oil at the oil outlet 10c of the compressor 10 enters the inlet of the indoor heat exchanger 12 (evaporator) through the oil discharge control device 16.

[0065] Specifically, when the air conditioner is a heating and cooling air conditioner, the controller is further configured to: when the air conditioner enters the cooling mode, control the two ends of the oil discharge control device to be respectively connected to the oil outlet of the compressor and the indoor heat exchanger, and control the outlet of the oil-gas separator to be connected to the outdoor heat exchanger; when the air conditioner enters the heating mode, control the two ends of the oil discharge control device to be respectively connected to the oil outlet of the compressor and the outdoor heat exchanger, and control the outlet of the oil-gas separator to be connected to the indoor heat exchanger.

[0066] When the air conditioner is a single-cool air conditioner, the controller is further configured to: control the two ends of the oil discharge control device to be respectively connected to the oil outlet of the compressor and the indoor heat exchanger, and control the outlet of the oil-gas separator to be connected to the outdoor heat exchanger.

[0067] Exemplarily, referring to Figure 6 , Figure 6 It is the first working flow chart of the controller in the air conditioner provided by the embodiment of the present invention. The controller is used to execute steps S21 to S24. The control method of the controller in the embodiment of the present invention can be applied to heating and cooling air conditioners and single-cool air conditioners.

[0068] Specifically, the controller is configured to: in response to an air conditioner startup operation, control the oil return control device and the oil discharge control device to be in a closed state; obtain the oil content in the refrigerant; compare the oil content with a preset oil content range, and adjust the opening and closing states of the oil return control device and the oil discharge control device according to the comparison result, so as to adjust the oil content in the refrigerant to be within a preset saturation range; wherein, the oil content range includes a low concentration range, a saturation concentration range, and a high concentration range.

[0069] Exemplarily, referring to the figure, Figure 7 It is the second working flowchart of the controller in the air conditioner provided by the embodiment of the present invention. The controller is configured to execute steps S11 to S17. When the air conditioner is turned on in the cooling (or heating) mode, immediately control the oil return control device and the oil discharge control device to be in a completely closed state. After running for a period of time, obtain the oil content OCR detected by the oil content detection device 17, and then detect whether the oil content OCR reaches the stable condition; the stable condition is determined according to this condition: when the fluctuation range of the oil content OCR value in 10 consecutive tests is within 10%, it can be determined at this time that the oil content OCR has been stable; if the fluctuation range of the OCR value exceeds 10%, continue to detect until it is within 10% to enter step S14. First, set two thresholds, OCR1 and OCR2, where OCR1 < OCR2. Then, the low concentration range satisfies: OCR < OCR1, the saturation concentration range satisfies: OCR1 ≤ OCR ≤ OCR2, and the high concentration range satisfies: OCR2 ≤ OCR. Assume OCR1 = 1% and OCR2 = 3%; when 1% ≤ OCR ≤ 3%, enter control mode 1; when OCR > 3%, enter control mode 2; when OCR < 1%, enter control mode 3.

[0070] Specifically, when the oil content is within the saturation concentration range, the controller is further configured to: control the oil return control device and the oil discharge control device to be in a closed state.

[0071] Exemplarily, when 1% ≤ OCR ≤ 3%, enter control mode 1. At this time, since the oil content of the refrigerant is within the optimal range, there is no need to increase or decrease the oil amount of the refrigerant. At this time, control the oil return control device and the oil discharge control device to be in a completely closed state.

[0072] Specifically, when the oil content is within the high concentration range, the controller is configured to: control the oil discharge control device to remain closed; adjust the valve opening of the oil return control device, and when it is detected that the oil content is less than a preset oil amount threshold, keep the current valve opening of the oil return control device unchanged; adjust the valve opening of the oil discharge control device so that the oil content is within the saturation concentration range.

[0073] Exemplarily, refer to Figure 8 , Figure 8 which is the third working flowchart of the controller in the air conditioner provided by the embodiment of the present invention. At this time, the controller is configured to execute steps S161 to S107. When OCR > 3%, enter control mode 2. First, control the oil discharge control device to remain in a fully closed state, then open the valve of the oil return control device (open gradually), and adjust its flow rate so that OCR satisfies OCR < OCR0, where OCR0 = 0.5%. As a result, most of the oil in the refrigerant, under the action of the oil-gas separator, converges into the oil return control device 15 through the oil outlet 14c of the oil-gas separator 14, and then flows back to the compressor 10 through the suction port 10b of the compressor. At this time, in the refrigeration mode, the amount of oil in the refrigerant flowing into the outdoor heat exchanger 11 (condenser) is very low, and in the heating mode, the amount of oil in the refrigerant flowing into the indoor heat exchanger 12 (condenser) is very low. When OCR < 0.5% is satisfied, control the oil return control device to stop adjusting the flow rate and keep the existing state. Next, open the valve of the oil discharge control device (open gradually), and adjust its flow rate so that OCR satisfies: 1% ≤ OCR ≤ 3%. After the action of the oil discharge control device 16, the amount of oil in the refrigerant flowing into the indoor heat exchanger 12 (evaporator) in the refrigeration mode increases, and the amount of oil in the refrigerant flowing into the outdoor heat exchanger 11 (evaporator) in the heating mode increases. Therefore, the purpose of first reducing and then increasing the oil content is to increase the OCR of the evaporator while still keeping OCR < OCR0 in the condenser, that is, to make the condenser have a lower oil content and the evaporator have a higher oil content.

[0074] Specifically, when the oil content is within the low concentration range, the controller is configured to: control the oil return control device to remain closed; adjust the valve opening of the oil return control device so that the oil content is within the saturated concentration range.

[0075] Exemplarily, refer to Figure 9 , Figure 9 which is the fourth working flowchart of the controller in the air conditioner provided by the embodiment of the present invention. At this time, the controller is configured to execute steps S171 to S174. When OCR < 1%, at this time, the condition that the oil content required by the condenser is relatively small is satisfied, but the oil content of the refrigerant entering the evaporator needs to be increased. At this time, control the oil return control device 15 to remain in a fully closed state, open the valve of the oil discharge control device (open gradually), and adjust its flow rate so that OCR satisfies: 1% ≤ OCR ≤ 3%. After the action of the oil discharge control device 16, the amount of oil in the refrigerant flowing into the indoor heat exchanger 12 (evaporator) in the refrigeration mode increases.

[0076] Compared with the prior art, the air conditioner disclosed in the present invention adds an oil return control device on the exhaust side of the compressor to reduce the lubricating oil content in the condenser; and adds an oil outlet at the bottom of the compressor (lubricating oil is usually filled at the bottom of the compressor for the moving parts of the compressor), and adds an oil discharging control device on the passage of this oil outlet to supply a small part of the oil at the bottom of the compressor to the inlet of the evaporator, and controls the operating modes of the oil discharging control device and the oil return control device based on the detected oil content in the refrigerant, so that the oil content in the refrigerant is within an ideal range. By adopting the embodiment of the present invention, both the mass ratio of lubricating oil to refrigerant in the condenser can be reduced, and the mass ratio of lubricating oil to refrigerant in the evaporator can be between an optimal range, so that the heat exchange performance of both the condenser and the evaporator reaches the best state.

[0077] See Figure 10 , Figure 10 is a flowchart of an air conditioner control method provided by an embodiment of the present invention. The air conditioner control method described in the embodiment of the present invention is implemented by a controller in the air conditioner. An air inlet, an air outlet and an oil outlet for discharging the lubricating oil inside the compressor are provided on the compressor of the air conditioner; an oil discharging control device, an oil-gas separator and an oil return control device are provided in the air conditioner. Among them, one end of the oil discharging control device is connected to the oil outlet of the compressor, and the other end communicates with the indoor heat exchanger or the outdoor heat exchanger. When the oil discharging control device is opened, the oil of the compressor is discharged into the pipeline to be mixed with the refrigerant; the oil-gas separator is provided with an inlet, an outlet and an oil outlet. The inlet is connected to the air outlet of the compressor, and the outlet communicates with the indoor heat exchanger or the outdoor heat exchanger; one end of the oil return control device is connected to the oil outlet of the oil-gas separator, and the other end is connected to the air inlet of the compressor. When the oil return control device is opened, the oil separated in the oil-gas separator is discharged into the compressor; then, the air conditioner control method includes:

[0078] S1. In response to the start operation of the air conditioner, control the oil return control device and the oil discharging control device to be in a closed state;

[0079] S2. Obtain the oil content in the refrigerant;

[0080] S3. Compare the oil content with a preset oil content range, and adjust the opening and closing states of the oil return control device and the oil discharging control device according to the comparison result to adjust the oil content in the refrigerant to be within the preset saturation range; wherein, the oil content range includes a low concentration range, a saturation concentration range and a high concentration range.

[0081] When the air conditioner is a heating and cooling air conditioner, the air conditioner control method further includes: when the air conditioner enters the cooling mode, controlling the two ends of the oil discharging control device to be respectively connected to the oil outlet of the compressor and the indoor heat exchanger, and controlling the outlet of the oil-gas separator to be connected to the outdoor heat exchanger; when the air conditioner enters the heating mode, controlling the two ends of the oil discharging control device to be respectively connected to the oil outlet of the compressor and the outdoor heat exchanger, and controlling the outlet of the oil-gas separator to be connected to the indoor heat exchanger.

[0082] When the air conditioner is a single-cooling air conditioner, the air conditioner control method further includes: controlling the two ends of the oil discharging control device to be respectively connected to the oil outlet of the compressor and the indoor heat exchanger, and controlling the outlet of the oil-gas separator to be connected to the outdoor heat exchanger.

[0083] When the oil content is within the saturation concentration range, the control mode is: controlling the oil return control device and the oil discharging control device to be in the closed state.

[0084] When the oil content is within the high concentration range, the control mode is: controlling the oil discharging control device to remain closed; adjusting the valve opening degree of the oil return control device, and when it is detected that the oil content is less than a preset oil quantity threshold, keeping the current valve opening degree of the oil return control device unchanged; adjusting the valve opening degree of the oil discharging control device so that the oil content is within the saturation concentration range.

[0085] When the oil content is within the low concentration range, the control mode is: controlling the oil return control device to remain closed; adjusting the valve opening degree of the oil return control device so that the oil content is within the saturation concentration range.

[0086] It should be noted that the working process of the air conditioner control method described in the embodiments of the present invention can refer to the working flowchart of the controller in the air conditioner described in the above embodiments, and will not be elaborated here.

[0087] Compared with the prior art, in the air conditioner control method disclosed by the present invention, an oil return control device is added on the exhaust side of the compressor to reduce the lubricating oil content in the condenser; and an oil outlet is added at the bottom of the compressor (lubricating oil is usually filled at the bottom of the compressor for lubricating the moving parts of the compressor), and an oil discharging control device is added on the passage of this oil outlet to supply a small part of the oil at the bottom of the compressor to the inlet of the evaporator. Based on the detected oil content in the refrigerant, the operation modes of the oil discharging control device and the oil return control device are controlled, so that the oil content in the refrigerant is within an ideal range. By adopting the embodiment of the present invention, not only can the mass ratio of the lubricating oil to the refrigerant in the condenser be reduced, but also the mass ratio of the lubricating oil to the refrigerant in the evaporator can be between an optimal range, so that the heat exchange performance of both the condenser and the evaporator reaches the best state.

[0088] The above is the preferred embodiment of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and modifications can be made, and these improvements and modifications are also regarded as the protection scope of the present invention.

Claims

1. An air conditioner, characterized in that, it includes: An indoor unit for adjusting the indoor temperature and / or humidity, and an indoor heat exchanger is provided in the indoor unit; An outdoor unit is connected to the indoor unit through a connecting pipe. The outdoor unit is used to provide the power for the refrigeration cycle. A compressor and an outdoor heat exchanger are provided in the outdoor unit. The compressor, the outdoor heat exchanger and the indoor heat exchanger form a refrigerant circuit through pipelines; an air inlet, an air outlet and an oil outlet for discharging the lubricating oil inside the compressor are provided on the compressor; An oil discharging control device is provided in the outdoor unit, one end is connected to the oil outlet of the compressor, and the other end is communicated with the indoor heat exchanger or the outdoor heat exchanger. When the oil discharging control device is opened, the oil of the compressor is discharged into the pipeline to be mixed with the refrigerant; An oil-gas separator is provided in the outdoor unit. An inlet, an outlet and an oil outlet are provided on the oil-gas separator; wherein, the inlet is connected to the air outlet of the compressor, and the outlet is communicated with the indoor heat exchanger or the outdoor heat exchanger; An oil return control device is provided in the outdoor unit, one end is connected to the oil outlet of the oil-gas separator, and the other end is connected to the air inlet of the compressor. When the oil return control device is opened, the oil separated in the oil-gas separator is discharged into the compressor; The controller is configured to: In response to the start operation of the air conditioner, control the oil return control device and the oil discharging control device to be in a closed state; Obtain the oil content in the refrigerant; Compare the oil content with a preset oil content range, and adjust the opening and closing states of the oil return control device and the oil discharging control device according to the comparison result, so as to adjust the oil content in the refrigerant to be within a preset saturation range; wherein, the oil content range includes a low concentration range, a saturation concentration range and a high concentration range.

2. The air conditioner according to claim 1, characterized in that, When the air conditioner is a heating and cooling air conditioner, the controller is further configured to: When the air conditioner enters the cooling mode, control the two ends of the oil discharging control device to be respectively connected to the oil outlet of the compressor and the indoor heat exchanger, and control the outlet of the oil-gas separator to be connected to the outdoor heat exchanger; When the air conditioner enters the heating mode, control the two ends of the oil discharging control device to be respectively connected to the oil outlet of the compressor and the outdoor heat exchanger, and control the outlet of the oil-gas separator to be connected to the indoor heat exchanger.

3. The air conditioner according to claim 1, characterized in that, When the air conditioner is a single-cooling air conditioner, the controller is further configured to: Control the two ends of the oil discharging control device to be respectively connected to the oil outlet of the compressor and the indoor heat exchanger, and control the outlet of the oil-gas separator to be connected to the outdoor heat exchanger.

4. The air conditioner according to claim 1, characterized in that, When the oil content is within the saturation concentration range, the controller is further configured to: Control the oil return control device and the oil discharging control device to be in a closed state.

5. As claimed in claim 1, characterized in that, When the oil content is within the high concentration range, the controller is configured to: Control the oil discharging control device to remain closed; Adjust the valve opening of the oil return control device, and when the detected oil content is less than the preset oil volume threshold, keep the current valve opening of the oil return control device unchanged; Adjust the valve opening of the oil discharge control device so that the oil content is within the saturation concentration range.

6. As described in claim 1, characterized in that, when the oil content is within the low concentration range, the controller is configured to: control the oil return control device to remain closed; adjust the valve opening of the oil return control device so that the oil content is within the saturation concentration range.

7. An air conditioner control method, characterized in that, The compressor of the air conditioner is provided with a suction port, a discharge port, and an oil outlet for discharging the lubricating oil inside the compressor; an oil discharge control device, an oil-gas separator, and an oil return control device are provided in the air conditioner. One end of the oil discharge control device is connected to the oil outlet of the compressor, and the other end communicates with the indoor heat exchanger or the outdoor heat exchanger. When the oil discharge control device is opened, the oil of the compressor is discharged into the pipeline to be mixed with the refrigerant; the oil-gas separator is provided with an inlet, an outlet, and an oil outlet. The inlet is connected to the discharge port of the compressor, and the outlet communicates with the indoor heat exchanger or the outdoor heat exchanger; one end of the oil return control device is connected to the oil outlet of the oil-gas separator, and the other end is connected to the suction port of the compressor. When the oil return control device is opened, the oil separated in the oil-gas separator is discharged into the compressor; then, the air conditioner control method includes: In response to the air conditioner startup operation, control the oil return control device and the oil discharge control device to be in the closed state; Obtain the oil content in the refrigerant; Compare the oil content with the preset oil volume range, and adjust the opening and closing states of the oil return control device and the oil discharge control device according to the comparison result to adjust the oil content in the refrigerant to be within the preset saturation range; wherein, the oil volume range includes a low concentration range, a saturation concentration range, and a high concentration range.

8. The air conditioner control method according to claim 7, characterized in that, when the oil content is within the saturation concentration range, the control mode is: control the oil return control device and the oil discharge control device to be in the closed state.

9. The air conditioner control method according to claim 7, characterized in that, when the oil content is within the high concentration range, the control mode is: control the oil discharge control device to remain closed; adjust the valve opening of the oil return control device, and when the detected oil content is less than the preset oil volume threshold, keep the current valve opening of the oil return control device unchanged; adjust the valve opening of the oil discharge control device so that the oil content is within the saturation concentration range.

10. The air conditioner control method according to claim 7, characterized in that, when the oil content is within the low concentration range, the control mode is: control the oil return control device to remain closed; adjust the valve opening of the oil return control device so that the oil content is within the saturation concentration range.

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