Air conditioning units and their control methods

Abstract

This invention discloses an air conditioning unit and its control method. The air conditioning unit includes: a subcooling branch, one end of which is connected to the subcooling refrigerant outlet of the subcooler, and the other end of which is connected to the inlet of the gas-liquid separator; a first suction branch, one end of which is connected to the outlet of the gas-liquid separator, and the other end of which is connected to the pipeline between the outdoor heat exchanger and the electronic expansion valve; a second suction branch, one end of which is connected to the suction port of the compressor, and the other end of which is connected to the pipeline between the main four-way valve and the indoor heat exchanger; and a control valve assembly for controlling the conduction of the subcooling branch, the first suction branch, and the second suction branch in a gas-liquid separation and drainage mode, so that the subcooling refrigerant of the subcooler enters the compressor after passing through the gas-liquid separator and the outdoor heat exchanger. This invention solves the problem in the prior art that air conditioning units are prone to gas-liquid separation and liquid accumulation in ultra-low temperature environments, resulting in slow refrigerant circulation and easy liquid slugging during startup. It avoids liquid refrigerant directly entering the compressor and causing liquid slugging, thereby improving the reliability of the compressor and the performance of the air conditioning unit.

Description

Technical Field

[0001] This invention relates to the field of air conditioning technology, and more specifically, to an air conditioning unit and its control method. Background Technology

[0002] With the continuous development of the refrigeration industry and the increasing demands of users, users have higher and higher requirements for air conditioning products. In particular, there is a huge demand for heating in some ultra-low temperature areas, which requires air conditioning products to maintain reliability in ultra-low temperature environments.

[0003] However, at extremely low ambient temperatures, the refrigerant in the air conditioning unit is prone to accumulating in liquid form in the gas-liquid separator (gas separator). When the unit starts up, the liquid refrigerant entering the compressor is prone to liquid slugging, reducing compressor reliability. Furthermore, the accumulation of liquid in the gas separator reduces the amount of refrigerant circulating in the system, slowing down the establishment of refrigerant circulation during unit startup and reducing the performance of the air conditioning unit.

[0004] There is currently no effective solution to the problem that air conditioning units are prone to liquid accumulation in ultra-low temperature environments, which leads to slow refrigerant circulation and easy liquid slugging during startup. Summary of the Invention

[0005] This invention provides an air conditioning unit and its control method to at least solve the problem in the prior art that air conditioning units in ultra-low temperature environments are prone to gas separation and liquid accumulation, resulting in slow refrigerant circulation and easy liquid slugging during startup.

[0006] To address the aforementioned technical problems, according to one aspect of the present invention, an air conditioning unit is provided, comprising:

[0007] The compressor, main four-way valve, outdoor heat exchanger, electronic expansion valve, subcooler, indoor heat exchanger, and gas-liquid separator are connected in sequence.

[0008] The subcooling branch is connected at one end to the subcooling refrigerant outlet of the subcooler and at the other end to the inlet of the gas-liquid separator.

[0009] The first intake branch is connected at one end to the outlet of the gas-liquid separator and at the other end to the pipeline between the outdoor heat exchanger and the electronic expansion valve.

[0010] The second intake branch is connected at one end to the intake port of the compressor and at the other end to the pipeline between the main four-way valve and the indoor heat exchanger.

[0011] The control valve assembly is used to control the conduction of the subcooling branch, the first suction branch and the second suction branch in the gas-liquid separation and drainage mode. The subcooled refrigerant of the subcooler enters the compressor after passing through the gas-liquid separator and the outdoor heat exchanger.

[0012] Furthermore, the control valve assembly includes:

[0013] The subcooling valve, located on the subcooling branch, is used to control the on / off state of the subcooling branch;

[0014] The second intake valve is located on the second intake branch and is used to control the opening and closing of the second intake branch.

[0015] Furthermore, the control valve assembly also includes:

[0016] The first intake valve is located on the first intake branch and is used to control the opening and closing of the first intake branch.

[0017] The third suction valve is located on the pipeline between the outlet of the gas-liquid separator and the suction port of the compressor, and is located between the first connection point and the suction port of the compressor. The first connection point is the connection point between the outlet of the gas-liquid separator and the first suction branch.

[0018] Furthermore, the control valve assembly also includes:

[0019] The four-way suction valve connects the outlet of the gas-liquid separator, the first suction branch, and the second suction branch to the suction port of the compressor.

[0020] Furthermore, it also includes:

[0021] The fourth suction valve is located on the pipeline between the main four-way valve and the gas-liquid separator, and between the second connection point and the main four-way valve. The second connection point is located between the subcooling valve and the inlet of the gas-liquid separator.

[0022] Furthermore, it also includes:

[0023] The subcooled electronic expansion valve is located on the subcooled refrigerant line of the subcooler.

[0024] A temperature sensor, located at the outlet of the gas-liquid separator, is used to detect the gas outlet temperature.

[0025] The first pressure sensor, located at the inlet of the gas-liquid separator, is used to detect low system pressure.

[0026] The second pressure sensor, located at the compressor's exhaust port, is used to detect high system pressure.

[0027] According to another aspect of the present invention, an air conditioning unit control method is provided, applied to the air conditioning unit as described above, the method comprising:

[0028] After the air conditioning unit enters the heating mode, determine whether the air conditioning unit meets the conditions for gas separation and liquid drainage.

[0029] If so, the air conditioning unit is controlled to enter the gas separation and liquid discharge mode via the control valve assembly;

[0030] Otherwise, the operation of the control valve assembly is controlled according to the heating mode.

[0031] Furthermore, the conditions for gas separation and liquid discharge include:

[0032] The outdoor ambient temperature is less than or equal to the preset temperature threshold, and the air conditioning unit's operating status includes at least one of the following: the air conditioning unit's continuous shutdown time is greater than or equal to the first preset time, the air conditioning unit restarts after the heating oil return operation is completed, or the air conditioning unit restarts after the heating defrosting operation is completed.

[0033] Furthermore, the air conditioning unit is controlled to enter the gas-liquid separation and drainage mode by controlling the valve assembly, including: controlling the third and fourth suction valves to close, the first and second suction valves to open, and controlling the subcooling valve to open and the electronic expansion valve to close; or, controlling the fourth suction valve to close, the second suction valve to open, the subcooling valve to open, the electronic expansion valve to close, and controlling the suction four-way valve to connect the outlet of the gas-liquid separator to the first suction branch, and the second suction branch to connect to the suction port of the compressor;

[0034] The operation of the control valve assembly is controlled according to the heating mode, including: controlling the opening of the third and fourth suction valves, the closing of the first and second suction valves, and controlling the closing of the subcooling valve and the opening of the electronic expansion valve; or, controlling the opening of the fourth suction valve, the closing of the second suction valve, the closing of the subcooling valve, the opening of the electronic expansion valve, and controlling the suction four-way valve to connect the outlet of the gas-liquid separator and the suction port of the compressor.

[0035] Furthermore, after controlling the air conditioning unit to enter the gas-liquid separation and drainage mode via the control valve assembly, it also includes:

[0036] Determine whether the air conditioning unit meets the gas-liquid separator discharge exit conditions; wherein, the gas-liquid separator discharge exit conditions include at least one of the following: the system high pressure is greater than or equal to the preset high pressure, the superheat of the gas-liquid separator outlet is greater than the preset temperature, and the running time of the air conditioning unit after entering the gas-liquid separator discharge is greater than or equal to the second preset time.

[0037] If so, the operation of the control valve assembly according to the heating mode will be triggered.

[0038] According to another aspect of the present invention, a storage medium containing computer-executable instructions is provided, which, when executed by a computer processor, are used to perform the air conditioning unit control method as described above.

[0039] This invention provides an air conditioning unit that prevents liquid accumulation in the gas separator. The unit includes a subcooling branch, one end of which is connected to the subcooled refrigerant outlet of the subcooler, and the other end to the inlet of the gas-liquid separator. A first suction branch is connected at one end to the outlet of the gas-liquid separator and at the other end to the pipeline between the outdoor heat exchanger and the electronic expansion valve. A second suction branch is connected at one end to the compressor's suction port and at the other end to the pipeline between the main four-way valve and the indoor heat exchanger. A control valve assembly is used to control the operation of the subcooling branch, the first suction branch, and the second suction branch in a gas-liquid separation and liquid discharge mode. The subcooled refrigerant from the subcooler passes through the gas-liquid separator and the outdoor heat exchanger before entering the compressor. This gas-liquid separation and liquid discharge mode establishes refrigerant circulation, allowing the liquid refrigerant in the gas separator to first evaporate and absorb heat in the outdoor heat exchanger before entering the compressor. This avoids liquid slugging caused by direct liquid refrigerant entering the compressor, improving compressor reliability. Simultaneously, it enables the compressor to quickly establish exhaust superheat, accelerating system refrigerant circulation and improving the performance of the air conditioning unit. Attached Figure Description

[0040] Figure 1 This is a schematic diagram of an optional structure of an air conditioning unit according to an embodiment of the present invention;

[0041] Figure 2 This is a schematic diagram of an optional refrigerant flow path for an air conditioning unit according to an embodiment of the present invention;

[0042] Figure 3 This is a schematic diagram of another optional refrigerant flow path for the air-to-liquid separation mode of an air conditioning unit according to an embodiment of the present invention;

[0043] Figure 4 This is a schematic diagram of an optional refrigerant flow path for an air conditioning unit according to an embodiment of the present invention, representing either the cooling or heating mode.

[0044] Figure 5 This is a schematic diagram of another optional refrigerant flow path for an air conditioning unit according to an embodiment of the present invention, in either the cooling or heating mode.

[0045] Figure 6 This is an optional flowchart of an air conditioning unit control method according to an embodiment of the present invention.

[0046] Explanation of reference numerals in the attached figures:

[0047] 1. Compressor; 2. Main four-way valve; 3. Outdoor heat exchanger; 4. Electronic expansion valve; 5. Subcooler; 6. Gas-liquid separator; 7. Subcooling valve; 8. Second suction valve; 9. First suction valve; 10. Third suction valve; 11. Suction four-way valve; 12. Fourth suction valve; 13. Subcooling electronic expansion valve; 14. Temperature sensor; 15. First pressure sensor; 16. Second pressure sensor; 17. Oil return valve; 18. Oil separator. Detailed Implementation

[0048] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0049] The terminology used in the embodiments of this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention. The singular forms “a,” “the,” and “the” as used in the embodiments of this invention and the appended claims are also intended to include the plural forms, and “multiple” generally includes at least two unless the context clearly indicates otherwise.

[0050] It should be understood that the term "and / or" used in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.

[0051] It should be understood that although the terms first, second, third, etc., may be used to describe controllers in embodiments of the present invention, these controllers should not be limited to these terms. These terms are only used to distinguish controllers connected to different devices. For example, without departing from the scope of embodiments of the present invention, a first controller may also be referred to as a second controller, and similarly, a second controller may also be referred to as a first controller.

[0052] Depending on the context, the words “if” or “suppose” as used here can be interpreted as “when” or “in response to determination” or “in response to detection.” Similarly, depending on the context, the phrases “if determination” or “if detection (of the stated condition or event)” can be interpreted as “when determination” or “in response to determination” or “when detection (of the stated condition or event)” or “in response to detection (of the stated condition or event).”

[0053] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that an article or device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such an article or device. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the article or device that includes said element.

[0054] The optional embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0055] Example 1

[0056] Under ultra-low ambient temperatures, liquid refrigerant easily accumulates in the gas separator of air conditioning units. This accumulation slows refrigerant circulation during unit startup, and the liquid refrigerant entering the compressor can cause liquid slugging, affecting compressor reliability. This invention proposes an ultra-low temperature air conditioning system and its control method. In a preferred embodiment 1, an air conditioning unit is provided that, by adding several suction branches and suction valves, allows the liquid refrigerant in the gas separator to first enter the outdoor heat exchanger for evaporation and heat absorption before entering the compressor when the unit starts up after liquid accumulation in the gas separator. Specifically… Figure 1 This diagram illustrates one possible structural design of the air conditioning unit, such as... Figure 1 As shown, the air conditioning unit includes:

[0057] The compressor 1, main four-way valve 2, outdoor heat exchanger 3, electronic expansion valve 4, subcooler 5, indoor heat exchanger (not shown) and gas-liquid separator 6 are connected in sequence.

[0058] The subcooling branch is connected at one end to the subcooling refrigerant outlet of the subcooler 5 and at the other end to the inlet of the gas-liquid separator 6. The subcooler 5 is divided into a normal refrigerant zone and a subcooling refrigerant zone. A subcooling electronic expansion valve 13 is installed after the inlet of the subcooling refrigerant zone and is located on the subcooling refrigerant pipeline of the subcooler 5. The subcooling branch is from the outlet of the subcooling refrigerant zone to the gas-liquid separator 6.

[0059] The first intake branch is connected at one end to the outlet of the gas-liquid separator 6 and at the other end to the pipeline between the outdoor heat exchanger 3 and the electronic expansion valve 4.

[0060] The second intake branch is connected at one end to the intake port of compressor 1 and at the other end to the pipeline between the main four-way valve 2 and the indoor heat exchanger.

[0061] The control valve assembly is used to control the conduction of the subcooling branch, the first suction branch and the second suction branch in the gas-liquid separation mode. The subcooled refrigerant of the subcooler 5 enters the compressor 1 after passing through the gas-liquid separator 6 and the outdoor heat exchanger 3.

[0062] In the above embodiments, an air conditioning unit for preventing liquid accumulation in the gas separator is provided. This unit includes a subcooling branch, one end of which is connected to the subcooling refrigerant outlet of the subcooler, and the other end to the inlet of the gas-liquid separator; a first suction branch, one end of which is connected to the outlet of the gas-liquid separator, and the other end to the pipeline between the outdoor heat exchanger and the electronic expansion valve; and a second suction branch, one end of which is connected to the compressor's suction port, and the other end to the pipeline between the main four-way valve and the indoor heat exchanger. A control valve assembly is used to control the operation of the subcooling branch, the first suction branch, and the second suction branch in the gas separator liquid discharge mode. The subcooling refrigerant from the subcooler passes through the gas-liquid separator and the outdoor heat exchanger before entering the compressor. This gas separator liquid discharge mode establishes refrigerant circulation, allowing the liquid refrigerant in the gas separator to first enter the outdoor heat exchanger for evaporation and heat absorption before entering the compressor. This avoids liquid slugging caused by the liquid refrigerant directly entering the compressor, improving compressor reliability. Simultaneously, it allows the compressor to quickly establish discharge superheat, accelerating system refrigerant circulation and improving the performance of the air conditioning unit.

[0063] In a preferred embodiment of the present invention, the control valve assembly includes: a subcooling valve 7, located on the subcooling branch, for controlling the on / off state of the subcooling branch; a first suction valve 9, located on the first suction branch, for controlling the on / off state of the first suction branch; a second suction valve 8, located on the second suction branch, for controlling the on / off state of the second suction branch; and a third suction valve 10, located on the pipeline between the outlet of the gas-liquid separator 6 and the suction port of the compressor 1, and located between a first connection point and the suction port of the compressor 1, wherein the first connection point is the connection point between the outlet of the gas-liquid separator 6 and the first suction branch. The third suction valve 10 can control the refrigerant from the gas-liquid separator 6 from directly entering the compressor 1. Working in conjunction with the first suction valve 9, it allows the gas-separated refrigerant to enter the first suction branch, then the second suction branch, and finally return to the compressor 1. In the gas-liquid separation and drainage mode, the subcooling valve 7, the first suction valve 9, and the second suction valve 8 are opened, and the third suction valve 10 is closed, so that the subcooling branch, the first suction branch, and the second suction branch are connected. The subcooled refrigerant of the subcooler 5 enters the compressor 1 after passing through the gas-liquid separator 6 and the outdoor heat exchanger 3. Figure 2 The diagram shows the refrigerant flow path of the air conditioning unit in gas-liquid separation mode, as shown below. Figure 2 As shown in the diagram, the dashed line represents the refrigerant flow path. The subcooled refrigerant from the subcooler 5 enters the compressor 1 after passing through the gas-liquid separator 6 and the outdoor heat exchanger 3. This prevents liquid refrigerant from directly entering the compressor 1 and causing liquid slugging, thus improving the reliability of the compressor 1. At the same time, it allows the compressor 1 to quickly establish exhaust superheat, accelerates the refrigerant circulation in the system, and improves the performance of the air conditioning unit.

[0064] In another preferred embodiment of the present invention, the control valve assembly includes: a subcooling valve 7, located on the subcooling branch, for controlling the on / off state of the subcooling branch; a second suction valve 8, located on the second suction branch, for controlling the on / off state of the second suction branch; and a suction four-way valve 11, through which the outlet of the gas-liquid separator 6, the first suction branch, and the second suction branch are connected to the suction port of the compressor 1. The suction four-way valve 11 replaces the first suction valve 9 and the third suction valve 10. In the gas-liquid separation and drainage mode, the suction four-way valve 11 connects the outlet of the gas-liquid separator 6 to the first suction branch, and the second suction branch to the suction port of the compressor 1, allowing the gas-separated refrigerant to enter the first suction branch, then the second suction branch, and finally return to the compressor 1. That is, in the gas-liquid separation and drainage mode, the subcooling branch, the first suction branch, and the second suction branch are connected, and the subcooled refrigerant of the subcooler 5 enters the compressor 1 after passing through the gas-liquid separator 6 and the outdoor heat exchanger 3. Figure 3 The diagram shows the refrigerant flow path of the air conditioning unit in gas-liquid separation mode, as shown below. Figure 3 As shown in the diagram, the dashed lines represent the refrigerant flow path.

[0065] like Figure 1 As shown, this air conditioning unit also includes: a fourth suction valve 12, located on the pipeline between the main four-way valve 2 and the gas-liquid separator 6, and located between the second connection point and the main four-way valve 2, wherein the second connection point is located between the subcooling valve 7 and the inlet of the gas-liquid separator 6.

[0066] In addition, it also includes: a subcooling electronic expansion valve 13, located on the subcooling refrigerant line of the subcooler 5, which is used to control the degree of subcooling; a temperature sensor 14, located at the outlet of the gas-liquid separator 6, which is used to detect the gas outlet temperature; a first pressure sensor 15, located at the inlet of the gas-liquid separator 6, which is used to detect the low pressure of the system; and a second pressure sensor 16, located at the exhaust port of the compressor 1, which is used to detect the high pressure of the system.

[0067] When the unit starts and operates normally in cooling mode, the main four-way valve 2 is de-energized, the electronic expansion valve 4 opens, controlling the opening of the third suction valve 10 and the fourth suction valve 12, while the first suction valve 9 and the second suction valve 8 close. The refrigerant flow in the system is consistent with that of a traditional air conditioning system in cooling mode. When the unit starts and operates normally in heating mode, the main four-way valve 2 is energized, the electronic expansion valve 4 opens, the third suction valve 10 and the fourth suction valve 12 open, while the first suction valve 9 and the second suction valve 8 close. The refrigerant flow in the system is consistent with that of a traditional air conditioning system in heating mode. (See attached...) Figure 4 As shown, this unit uses an intake valve.

[0068] For units that use a four-way suction valve 11 instead of a suction valve, during normal startup in cooling mode, the main four-way valve 2 and suction four-way valve 11 are de-energized, the electronic expansion valve 4 opens, the fourth suction valve 12 opens, and the second suction valve 8 closes. During normal startup in heating mode, the main four-way valve 2 is energized, suction four-way valve 11 is de-energized, the electronic expansion valve 4 opens, the fourth suction valve 12 opens, and the second suction valve 8 closes, as shown in the attached diagram. Figure 5 As shown.

[0069] In addition, this air conditioning unit also has an oil return valve 17 to control the oil return and prevent the compressor from running out of oil.

[0070] Example 2

[0071] In a preferred embodiment 2 of the present invention, an air conditioning unit control method is provided, which is applied to the air conditioning unit in embodiment 1 described above. Specifically, Figure 6 An optional flowchart of the method is shown, such as Figure 6 As shown, the method includes the following steps S602-S606:

[0072] S602: After the air conditioning unit enters the heating mode, determine whether the air conditioning unit meets the conditions for gas separation and liquid drainage.

[0073] S604: If so, the air conditioning unit is controlled to enter the gas separation and liquid discharge mode via the control valve assembly;

[0074] S606: Otherwise, control the operation of the control valve assembly according to the heating mode.

[0075] In the above embodiments, an air conditioning unit for preventing liquid accumulation in the gas separator is provided. This unit includes a subcooling branch, one end of which is connected to the subcooling refrigerant outlet of the subcooler, and the other end to the inlet of the gas-liquid separator; a first suction branch, one end of which is connected to the outlet of the gas-liquid separator, and the other end to the pipeline between the outdoor heat exchanger and the electronic expansion valve; and a second suction branch, one end of which is connected to the compressor's suction port, and the other end to the pipeline between the main four-way valve and the indoor heat exchanger. A control valve assembly is used to control the operation of the subcooling branch, the first suction branch, and the second suction branch in the gas separator liquid discharge mode. The subcooling refrigerant from the subcooler passes through the gas-liquid separator and the outdoor heat exchanger before entering the compressor. This gas separator liquid discharge mode establishes refrigerant circulation, allowing the liquid refrigerant in the gas separator to first enter the outdoor heat exchanger for evaporation and heat absorption before entering the compressor. This avoids liquid slugging caused by the liquid refrigerant directly entering the compressor, improving compressor reliability. Simultaneously, it allows the compressor to quickly establish discharge superheat, accelerating system refrigerant circulation and improving the performance of the air conditioning unit.

[0076] The conditions for gas separation and liquid discharge include: the outdoor ambient temperature is less than or equal to the preset temperature threshold, and the operating status of the air conditioning unit includes at least one of the following: the continuous shutdown time of the air conditioning unit is greater than or equal to the first preset time, the air conditioning unit is restarted after the heating oil return operation is completed, and the air conditioning unit is restarted after the heating defrosting operation is completed.

[0077] The air conditioning unit is controlled to enter the gas-liquid separation and drainage mode by controlling the valve assembly, including: controlling the third and fourth suction valves to close, the first and second suction valves to open, and controlling the subcooling valve to open and the electronic expansion valve to close; or, controlling the fourth suction valve to close, the second suction valve to open, the subcooling valve to open, the electronic expansion valve to close, and controlling the suction four-way valve to connect the outlet of the gas-liquid separator to the first suction branch, and the second suction branch to the compressor suction port; the refrigerant flow diagram of the gas-liquid separation and drainage mode is as follows. Figure 2 and 3 As shown.

[0078] The operation of the control valve assembly is controlled according to the heating mode, including: controlling the opening of the third and fourth suction valves, closing the first and second suction valves, and controlling the closing of the subcooling valve and the opening of the electronic expansion valve; or, controlling the opening of the fourth suction valve, closing of the second suction valve, closing of the subcooling valve, opening of the electronic expansion valve, and controlling the suction four-way valve to connect the outlet of the gas-liquid separator and the suction port of the compressor. The refrigerant flow diagram for heating mode is as follows: Figure 4 and 5 As shown.

[0079] After controlling the air conditioning unit to enter the gas-liquid separation and drainage mode through the control valve assembly, the process also includes: determining whether the air conditioning unit meets the gas-liquid separation and drainage exit conditions; wherein, the gas-liquid separation and drainage exit conditions include at least one of the following: the system high pressure is greater than or equal to the preset high pressure, the superheat of the gas-liquid separator outlet is greater than the preset temperature, and the running time of the air conditioning unit after entering the gas-liquid separation and drainage mode is greater than or equal to the second preset time; if so, the operation of the control valve assembly is triggered according to the heating mode.

[0080] In heating mode, if the outdoor ambient temperature is ≤T℃ before the unit is to be started, and the unit is to be started after the heating oil return operation or the heating defrosting operation is to be started, the unit will operate according to the gas separation and liquid drainage start control mode when restarting. Otherwise, the unit will operate according to the normal start operation and will not enter the gas separation and liquid drainage start control mode.

[0081] When the unit is running in the gas-liquid separation start-up control mode, the system high pressure T0, system low pressure T1 and gas-liquid separation outlet temperature T2 are monitored in real time. When any of the following conditions are met, the unit exits the gas-liquid separation start-up control: system high pressure ≥ A℃, gas-liquid separation outlet superheat △T(T2-T1) ≥ B℃, or start-up time ≥ y min.

[0082] The values ​​of the aforementioned critical point AB serve as the conditions for the system to exit gas separator drainage control. When the system pressure rises to a high value, the refrigerant is generally in a gaseous state, and there is no need to worry about compressor liquid slugging. Similarly, when the superheat at the gas separator outlet is large, it indicates that the refrigerant has also turned into a gaseous state, and the gas separator drainage is complete. Ensure that the gas separator drainage is completed while restoring normal control operation as soon as possible.

[0083] Example 3

[0084] Based on the air conditioning unit control method provided in Embodiment 2 above, in a preferred embodiment 3 of the present invention, a storage medium containing computer-executable instructions is also provided, wherein the computer-executable instructions are used to execute the air conditioning unit control method as described above when executed by a computer processor.

[0085] In the above embodiments, an air conditioning unit for preventing liquid accumulation in the gas separator is provided. This unit includes a subcooling branch, one end of which is connected to the subcooling refrigerant outlet of the subcooler, and the other end to the inlet of the gas-liquid separator; a first suction branch, one end of which is connected to the outlet of the gas-liquid separator, and the other end to the pipeline between the outdoor heat exchanger and the electronic expansion valve; and a second suction branch, one end of which is connected to the compressor's suction port, and the other end to the pipeline between the main four-way valve and the indoor heat exchanger. A control valve assembly is used to control the operation of the subcooling branch, the first suction branch, and the second suction branch in the gas separator liquid discharge mode. The subcooling refrigerant from the subcooler passes through the gas-liquid separator and the outdoor heat exchanger before entering the compressor. This gas separator liquid discharge mode establishes refrigerant circulation, allowing the liquid refrigerant in the gas separator to first enter the outdoor heat exchanger for evaporation and heat absorption before entering the compressor. This avoids liquid slugging caused by the liquid refrigerant directly entering the compressor, improving compressor reliability. Simultaneously, it allows the compressor to quickly establish discharge superheat, accelerating system refrigerant circulation and improving the performance of the air conditioning unit.

[0086] Other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not invented by the invention. The specification and examples are to be considered exemplary only, and the true scope and spirit of the invention are indicated by the following claims.

[0087] It should be understood that the present invention is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of the invention is limited only by the appended claims.

Claims

1. A method for controlling an air conditioning unit, the air conditioning unit comprising: The air conditioning unit is characterized by a compressor (1), a main four-way valve (2), an outdoor heat exchanger (3), an electronic expansion valve (4), a subcooler (5), an indoor heat exchanger, and a gas-liquid separator (6) connected in sequence. The unit further comprises: a subcooling branch, one end of which is connected to the subcooling refrigerant outlet of the subcooler (5), and the other end of which is connected to the inlet of the gas-liquid separator (6); and a first suction branch, one end of which is connected to the outlet of the gas-liquid separator (6), and the other end of which is connected to the outdoor heat exchanger (3) and the gas-liquid separator (6). The pipeline connection between the electronic expansion valve (4) is as follows: the second suction branch is connected at one end to the suction port of the compressor (1) and at the other end to the pipeline between the main four-way valve (2) and the indoor heat exchanger; the control valve assembly is used to control the conduction of the subcooling branch, the first suction branch and the second suction branch in the gas separation and liquid discharge mode, and the subcooling refrigerant of the subcooler (5) enters the compressor (1) after passing through the gas-liquid separator (6) and the outdoor heat exchanger (3); The method includes: After the air conditioning unit enters the heating mode, it is determined whether the air conditioning unit meets the conditions for gas separation and liquid drainage. The conditions for gas separation and liquid drainage include: the outdoor ambient temperature is less than or equal to a preset temperature threshold, and the operating status of the air conditioning unit includes at least one of the following: the continuous shutdown time of the air conditioning unit is greater than or equal to a first preset time, the air conditioning unit is restarted after the heating oil return operation is completed, and the air conditioning unit is restarted after the heating defrosting operation is completed. If so, the air conditioning unit is controlled to enter the gas-liquid separation and drainage mode via the control valve assembly; then, the process further includes: determining whether the air conditioning unit meets the gas-liquid separation and drainage exit conditions; wherein, the gas-liquid separation and drainage exit conditions include at least one of the following: the system high pressure is greater than or equal to a preset high pressure, the superheat of the gas-liquid separator outlet is greater than a preset temperature, and the running time of the air conditioning unit after entering the gas-liquid separation and drainage mode is greater than or equal to a second preset time; if so, the process of controlling the air conditioning unit to enter the heating mode via the control valve assembly is triggered. Otherwise, the operation of the control valve assembly is controlled according to the heating mode described above.

2. The air conditioning unit control method according to claim 1, characterized in that, The control valve assembly includes: The subcooling valve (7) is located on the subcooling branch and is used to control the on / off state of the subcooling branch; The second intake valve (8) is located on the second intake branch and is used to control the opening and closing of the second intake branch.

3. The air conditioning unit control method according to claim 2, characterized in that, The control valve assembly also includes: The first intake valve (9) is located on the first intake branch and is used to control the opening and closing of the first intake branch. The third suction valve (10) is located on the pipeline between the outlet of the gas-liquid separator (6) and the suction port of the compressor (1), and is located between the first connection point and the suction port of the compressor (1), wherein the first connection point is the connection point between the outlet of the gas-liquid separator (6) and the first suction branch.

4. The air conditioning unit control method according to claim 3, characterized in that, The control valve assembly also includes: The four-way suction valve (11) is used to connect the outlet of the gas-liquid separator (6), the first suction branch and the second suction branch to the suction port of the compressor (1).

5. The air conditioning unit control method according to claim 4, characterized in that, The air conditioning unit also includes: The fourth suction valve (12) is located on the pipeline between the main four-way valve (2) and the gas-liquid separator (6), and is located between the second connection point and the main four-way valve (2), wherein the second connection point is located between the subcooling valve (7) and the inlet of the gas-liquid separator (6).

6. The air conditioning unit control method according to claim 2, characterized in that, The air conditioning unit also includes: The subcooled electronic expansion valve (13) is located on the subcooled refrigerant line of the subcooler (5); A temperature sensor (14) is located at the outlet of the gas-liquid separator (6) and is used to detect the gas outlet temperature. The first pressure sensor (15) is located at the inlet of the gas-liquid separator (6) and is used to detect low system pressure; The second pressure sensor (16) is located at the exhaust port of the compressor (1) and is used to detect the high pressure of the system.

7. The air conditioning unit control method according to claim 5, characterized in that, The air conditioning unit is controlled to enter the gas-liquid separation and drainage mode by controlling the valve assembly, including: controlling the third and fourth suction valves to close, the first and second suction valves to open, and controlling the subcooling valve to open and the electronic expansion valve to close; or, controlling the fourth suction valve to close, the second suction valve to open, the subcooling valve to open, the electronic expansion valve to close, and controlling the suction four-way valve to connect the outlet of the gas-liquid separator to the first suction branch, and the second suction branch to connect to the suction port of the compressor; The operation of the control valve assembly is controlled according to the heating mode, including: controlling the third and fourth suction valves to open, the first and second suction valves to close, and controlling the subcooling valve to close and the electronic expansion valve to open; or, controlling the fourth suction valve to open, the second suction valve to close, the subcooling valve to close, the electronic expansion valve to open, and controlling the suction four-way valve to connect the outlet of the gas-liquid separator and the suction port of the compressor.

8. A storage medium containing computer-executable instructions, characterized in that, The computer-executable instructions, when executed by a computer processor, are used to perform the air conditioning unit control method as described in any one of claims 1 to 7.

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