System and control method for preventing compressor startup liquid return in a refrigeration air conditioner

Abstract

The application provides a system and control method for preventing compressor startup liquid return of a refrigeration air conditioner, and the system for preventing compressor startup liquid return of the refrigeration air conditioner comprises an indoor unit, a compressor, a gas-liquid separator, an oil separator, a liquid accumulator, an outdoor heat exchanger, a four-way valve and an electronic expansion valve which are connected into a circulation loop through pipelines; the liquid accumulator is arranged between the indoor unit and the outdoor unit, a first interface of the liquid accumulator is connected with the electronic expansion valve, a second interface of the liquid accumulator is connected with the indoor unit, and a third interface of the liquid accumulator is connected with the gas-liquid separator; the system for preventing compressor startup liquid return of the refrigeration air conditioner can adopt different modes for starting according to different liquid level heights when starting. The system for preventing compressor startup liquid return of the refrigeration air conditioner provided by the application has the following advantages: 1. The compressor startup liquid return can be avoided, and the compressor is not damaged; 2. The compressor startup frequency can be quickly improved, the air conditioner refrigeration and heating effects in the early stage are improved, and the comfort is improved.

Description

Technical Field

[0001] This invention relates to the field of air conditioning, and more specifically, to a system and control method for preventing liquid return during compressor startup in a refrigeration air conditioner. Background Technology

[0002] Currently, to prevent liquid backflow in the compressor during long-term operation of refrigeration and air conditioning systems, a gas-liquid separator is typically added before the compressor intakes to store excess liquid. Furthermore, to prevent liquid backflow during startup, the system usually starts at a low frequency, gradually increasing the frequency. However, this technology still has the following problems in its application.

[0003] 1. When there is too much liquid refrigerant in the gas-liquid separator, it may still cause liquid to return to the compressor during startup, damaging the compressor;

[0004] 2. Insufficient start-up frequency results in poor cooling performance in the early stages after the air conditioner starts, affecting comfort.

[0005] In view of this, the present invention is hereby proposed. Summary of the Invention

[0006] The purpose of this invention is to propose a control system and method for refrigeration air conditioners that prevents liquid return during compressor startup, in order to solve the problems in the prior art where, when there is too much liquid refrigerant in the gas-liquid separator, liquid return to the compressor may still occur during startup, damaging the compressor; and the low start-up frequency leads to poor cooling effect in the early stage after the air conditioner starts, affecting comfort.

[0007] To achieve the above objectives, the technical solution of the present invention is implemented as follows:

[0008] A refrigeration air conditioning system for preventing compressor start-up liquid return includes an indoor unit, a compressor, a gas-liquid separator, an oil separator, a liquid receiver, an outdoor heat exchanger, a four-way valve, and an electronic expansion valve, all connected in a circulation loop via piping. A liquid receiver is installed between the indoor and outdoor units. A first port of the liquid receiver is connected to the electronic expansion valve, a second port is connected to the indoor unit, and a third port is connected to the gas-liquid separator. The system can start in different modes based on different liquid levels upon startup.

[0009] The present invention discloses a refrigeration air conditioning system that prevents compressor liquid return during startup. When the system is turned on, it can adopt different startup modes according to different liquid levels. First, it can avoid compressor liquid return during startup and prevent damage to the compressor. Second, it can quickly increase the compressor startup frequency, improve the initial air conditioning cooling and heating effect, and improve comfort.

[0010] Furthermore, a first return gas pipe is provided on the gas-liquid separator, and the gas-liquid separator is connected to the four-way valve through the first return gas pipe. A second solenoid valve is provided on the first return gas pipe. A second return gas pipe is provided on the gas-liquid separator, and the gas-liquid separator is connected to the compressor through the second return gas pipe. A third solenoid valve is provided on the second return gas pipe. A first branch is provided on the first return gas pipe, one end of which is connected between the oil separator and the four-way valve. The other end of the first branch is connected between the gas-liquid separator and the second solenoid valve. A first solenoid valve is provided on the first branch. A fourth solenoid valve is provided between the gas-liquid separator and the liquid receiver.

[0011] Furthermore, a liquid level sensor is installed inside the gas-liquid separator to detect the liquid level height inside the gas-liquid separator.

[0012] This setting facilitates the detection of the liquid level within the gas-liquid separator.

[0013] Furthermore, an oil return hole is provided inside the gas-liquid separator.

[0014] A second aspect of the present invention provides a control method for preventing liquid return during compressor startup in a refrigeration air conditioner. This control method uses any one of the systems described above for preventing liquid return during compressor startup in a refrigeration air conditioner. The control method includes the following steps:

[0015] When a refrigeration air conditioning system designed to prevent compressor start-up and liquid return occurs: upon receiving a start-up command, the liquid level height h1 in the gas-liquid separator is acquired; it is then determined whether the liquid level height h1 ≥ the first set value h1. 设1 If yes, the compressor starts in the first mode, and the compressor frequency rises to the target frequency at a first rate; if no, the compressor starts in the second mode, and the compressor frequency rises to the target frequency at a second rate; the second rate is greater than the first rate.

[0016] This invention discloses a refrigeration air conditioning system that prevents compressor liquid backflow during startup. The system can adopt different startup modes based on different liquid levels. Firstly, it avoids liquid backflow into the compressor during startup, preventing damage to the compressor. Secondly, it can quickly increase the compressor startup frequency, improving the initial cooling and heating effect of the air conditioning and enhancing comfort. Upon receiving a startup command, the system obtains the liquid level height h1 in the gas-liquid separator and determines whether the liquid level height h1 ≥ the first set value h. 设1If yes, it indicates that the liquid level height h1 in the gas-liquid separator is high, and the compressor starts in the first mode, with the compressor frequency rising to the target frequency at the first rate; if no, it indicates that the liquid level height h1 in the gas-liquid separator is low, and the compressor starts in the second mode, with the compressor frequency rising to the target frequency at the second rate. The second rate is greater than the first rate, which shortens the compressor frequency change cycle, quickly rises to the target frequency, improves the initial air conditioning cooling and heating effect, and enhances comfort.

[0017] Furthermore, the control method for preventing the compressor from starting and returning liquid to the refrigeration air conditioner also includes the following steps:

[0018] When a refrigeration air conditioning system that prevents compressor start-up and liquid return is shut down: After receiving a shutdown command, the liquid level height h2 in the gas-liquid separator is retrieved again; if the liquid level height h2 ≥ the first set value h... 设1 Then it enters the liquid collection mode, introducing the refrigerant liquid in the gas-liquid separator into the liquid receiver for storage.

[0019] When the system is shut down, if the liquid level height h2 ≥ the first set value h 设1 Then, it enters the liquid collection mode, introducing excess liquid refrigerant from the gas-liquid separator into the liquid receiver for storage. This can minimize the occurrence of compressor liquid slugging during the next startup and ensure the safe operation of the compressor.

[0020] Furthermore, after entering the liquid recovery mode, the following steps are included: the refrigeration and air conditioning system that prevents the compressor from starting and returning liquid operates in heating mode. After the compressor reaches the target operating frequency, the first solenoid valve and the fourth solenoid valve are opened, and the second solenoid valve and the third solenoid valve are closed. The refrigerant liquid in the gas-liquid separator is introduced from the bottom of the gas-liquid separator through the fourth solenoid valve into the liquid receiver for storage.

[0021] This configuration allows the first and fourth solenoid valves to be opened and the second and third solenoid valves to be closed before the system shuts down. At this time, the high-pressure refrigerant gas at the compressor outlet enters the gas-liquid separator. Using the high pressure built up by the compressor, the liquid refrigerant in the gas-liquid separator is introduced into the liquid receiver for storage. This can minimize the occurrence of compressor liquid slugging during the next startup and ensure the safe operation of the compressor.

[0022] Furthermore, the refrigeration air conditioning system that prevents the compressor from starting and returning liquid also includes the following steps when shutting down: if the liquid level height h2 < the second set value h 设2 If the first, second, third, and fourth solenoid valves are closed, then the first, second, third, and fourth solenoid valves will be closed.

[0023] This setting ensures that before the system stops running, the first, second, third, and fourth solenoid valves are closed, i.e., all inlet and outlet solenoid valves of the gas-liquid separator are closed, keeping the gas-liquid separator in a sealed space to prevent refrigerant migration and thus minimizing the possibility of compressor liquid slugging during the next startup, thereby ensuring the safe operation of the compressor.

[0024] Furthermore, the liquid level height at the oil return hole in the gas-liquid separator is A mm, and the first set value of the liquid level is h. 设1 The value range is (A+40, A+60], and the first set value of the liquid level h 设1 The unit is mm.

[0025] Furthermore, the second set value h of the liquid level 设2 The value range is [A+20, A+40), and the second set value h of the liquid level is... 设2 The unit is mm.

[0026] This invention proposes a system and control method for preventing liquid return during compressor startup in refrigeration air conditioning systems. Compared with the prior art, the system and control method for preventing liquid return during compressor startup described in this invention have the following advantages:

[0027] 1) The present invention provides a system and control method for preventing compressor liquid return during startup. When the system is started, it can adopt different modes to start according to different liquid levels. First, it can prevent compressor liquid return during startup and avoid damage to the compressor. Second, it can quickly increase the compressor startup frequency, improve the initial air conditioning cooling and heating effect, and improve comfort.

[0028] 2) The refrigeration air conditioning system and control method described in this invention prevents liquid return during compressor startup. When the system is shut down, excess liquid refrigerant in the gas-liquid separator is introduced into the liquid receiver for storage, which can minimize the occurrence of compressor liquid slugging during the next startup and ensure the safe operation of the compressor.

[0029] 3) The refrigeration air conditioning system and control method described in this invention prevents the compressor from returning liquid during startup. When the system is shut down, the gas-liquid separator is in a sealed space, which can prevent refrigerant from other locations from entering, thereby minimizing the occurrence of compressor liquid slugging during the next startup and ensuring the safe operation of the compressor. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of a refrigeration air conditioning system for preventing compressor start-up and liquid return, as described in an embodiment of the present invention.

[0031] Figure 2This is a flowchart illustrating a control method for preventing liquid return during compressor startup in a refrigeration air conditioning system, as described in an embodiment of the present invention.

[0032] Figure 3 This is a flowchart illustrating a control method for preventing liquid return during compressor startup in a refrigeration air conditioning system according to an embodiment of the present invention.

[0033] Explanation of reference numerals in the attached figures:

[0034] 1. Compressor; 2. Gas-liquid separator; 21. Liquid level sensor; 22. First return gas pipe; 23. Second return gas pipe; 24. First branch; 3. Oil separator; 4. Liquid receiver; 41. First interface; 42. Second interface; 43. Third interface; 5. Four-way valve; 6. Outdoor heat exchanger; 7. Indoor unit; 81. First solenoid valve; 82. Second solenoid valve; 83. Third solenoid valve; 84. Fourth solenoid valve; 85. Electronic expansion valve. Detailed Implementation

[0035] It should be noted that, unless otherwise specified, the embodiments and features described in the embodiments of the present invention can be combined with each other. The descriptions of "first," "second," etc., mentioned in the embodiments of the present invention are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0036] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0037] Example 1

[0038] This embodiment proposes a refrigeration air conditioning system to prevent the compressor from returning liquid upon startup, such as... Figure 1 As shown, the refrigeration and air conditioning system for preventing compressor start-up liquid return includes an indoor unit 7, a compressor 1, a gas-liquid separator 2, an oil separator 3, a liquid receiver 4, an outdoor heat exchanger 6, a four-way valve 5, and an electronic expansion valve 85, all connected in a circulation loop via pipelines. A liquid receiver 4 is installed between the indoor unit 7 and the outdoor unit. The first port 41 of the liquid receiver 4 is connected to the electronic expansion valve 85, the second port 42 of the liquid receiver 4 is connected to the indoor unit 7, and the third port 43 of the liquid receiver 4 is connected to the gas-liquid separator 2. The refrigeration and air conditioning system for preventing compressor start-up liquid return can start in different modes according to different liquid levels when it is turned on.

[0039] The refrigeration air conditioning system described in this embodiment prevents compressor liquid return during startup. When the system is turned on, it can adopt different startup modes according to different liquid levels. First, it can prevent compressor 1 from returning liquid during startup and avoid damaging compressor 1. Second, it can quickly increase the startup frequency of compressor 1, improve the initial air conditioning cooling and heating effect, and improve comfort.

[0040] Specifically, such as Figure 1 As shown, a first return pipe 22 is provided on the gas-liquid separator 2, and the gas-liquid separator 2 is connected to the four-way valve 5 through the first return pipe 22. A second solenoid valve 82 is provided on the first return pipe 22. A second return pipe 23 is provided on the gas-liquid separator 2, and the gas-liquid separator 2 is connected to the compressor 1 through the second return pipe 23. A third solenoid valve 83 is provided on the second return pipe 23. A first branch 24 is provided on the first return pipe 22. One end of the first branch 24 is connected between the oil separator 3 and the four-way valve 5. The other end of the first branch 24 is connected between the gas-liquid separator 2 and the second solenoid valve 82. A first solenoid valve 81 is provided on the first branch 24. A fourth solenoid valve 84 is provided between the gas-liquid separator 2 and the liquid receiver 4.

[0041] Specifically, a liquid level sensor 21 is installed inside the gas-liquid separator 2, and the liquid level sensor 21 is used to detect the liquid level height inside the gas-liquid separator 2.

[0042] This setting facilitates the detection of the liquid level height inside the gas-liquid separator 2.

[0043] Specifically, an oil return hole is provided inside the gas-liquid separator 2.

[0044] This embodiment also proposes a control method for refrigeration air conditioners to prevent liquid return during compressor startup.

[0045] The refrigeration air conditioning system for preventing compressor start-up and liquid return uses a control method for preventing compressor start-up and liquid return. The control method for preventing compressor start-up and liquid return uses any one of the refrigeration air conditioning systems for preventing compressor start-up and liquid return.

[0046] The control method for preventing the compressor from starting and returning liquid to the refrigeration air conditioner includes the following steps:

[0047] like Figure 2 As shown, when the refrigeration air conditioning system that prevents the compressor from starting and returning liquid is turned on: upon receiving the start command, the liquid level height h1 in the gas-liquid separator 2 is obtained; it is then determined whether the liquid level height h1 ≥ the first set value h1. 设1If yes, then start in the first mode, and the frequency of compressor 1 rises to the target frequency at a first rate; if no, then start in the second mode, and the frequency of compressor 1 rises to the target frequency at a second rate; the second rate is greater than the first rate.

[0048] This embodiment describes a control method for preventing compressor backflow during air conditioning startup. When the system starts up, it can adopt different startup modes based on different liquid levels. Firstly, it avoids liquid backflow from compressor 1 during startup, preventing damage to compressor 1. Secondly, it can quickly increase the startup frequency of compressor 1, improving the initial cooling and heating effect of the air conditioning and enhancing comfort. Upon receiving a startup command, the liquid level height h1 in the gas-liquid separator 2 is obtained; it is then determined whether the liquid level height h1 ≥ the first set value h. 设1 If yes, it indicates that the liquid level h1 in the gas-liquid separator 2 is high, and the compressor 1 is started in the first mode, with the compressor 1 frequency rising to the target frequency at the first rate; if no, it indicates that the liquid level h1 in the gas-liquid separator 2 is not high, and the compressor 1 is started in the second mode, with the compressor 1 frequency rising to the target frequency at the second rate. The second rate is greater than the first rate, which shortens the frequency change cycle of the compressor 1, allowing it to rise to the target frequency quickly, thereby improving the initial air conditioning cooling and heating effect and enhancing comfort.

[0049] like Figure 3 As shown, when the refrigeration air conditioning system that prevents the compressor from starting and returning liquid is shut down: after receiving the shutdown command, the liquid level height h2 in the gas-liquid separator 2 is obtained again; it is then determined whether the liquid level height h2 ≥ the first set value h. 设1 If the liquid level height h2 ≥ the first set value of the liquid level h 设1 Then, it enters the liquid collection mode, introducing the refrigerant liquid in the gas-liquid separator 2 into the liquid receiver 4 for storage.

[0050] This embodiment describes a control method for preventing liquid return during compressor startup in a refrigeration air conditioner. When the system is shut down, if the liquid level height h2 ≥ the first set value h... 设1 Then, it enters the liquid collection mode, which introduces the excess liquid refrigerant in the gas-liquid separator into the liquid receiver 4 for storage. This can minimize the occurrence of liquid slugging in compressor 1 during the next startup and ensure the safe operation of compressor 1.

[0051] Specifically, after entering the liquid recovery mode, the following steps are included: the refrigeration and air conditioning system that prevents the compressor from starting and returning liquid operates in heating mode. After the compressor 1 reaches the target operating frequency, the first solenoid valve 81 and the fourth solenoid valve 84 are opened, and the second solenoid valve 82 and the third solenoid valve 83 are closed. The refrigerant liquid in the gas-liquid separator 2 is introduced from the bottom of the gas-liquid separator 2 through the fourth solenoid valve 84 into the liquid receiver 4 for storage.

[0052] This configuration allows the first solenoid valve 81 and the fourth solenoid valve 84 to be opened and the second solenoid valve 82 and the third solenoid valve 83 to be closed before the system stops operating. At this time, the high-pressure refrigerant gas at the outlet of the compressor 1 enters the gas-liquid separator 2. Using the high pressure established by the compressor 1, the liquid refrigerant in the gas-liquid separator 2 is introduced into the liquid receiver 4 for storage. This can minimize the occurrence of liquid slugging in the compressor 1 during the next startup and ensure the safe operation of the compressor 1.

[0053] Specifically, such as Figure 3 As shown, the refrigeration air conditioning system that prevents the compressor from starting and returning liquid also includes the following steps when shutting down: if the liquid level height h2 < the first set value h 设1 If so, determine whether the liquid level height h2 is less than the second set value h. 设2 If so, then close the first solenoid valve 81, the second solenoid valve 82, the third solenoid valve 83, and the fourth solenoid valve 84.

[0054] If the liquid level height h2 < the second set value of the liquid level h 设2 If the system shuts down, the first solenoid valve 81, the second solenoid valve 82, the third solenoid valve 83, and the fourth solenoid valve 84 will be closed. This setting ensures that before the system ends, the first solenoid valve 81, the second solenoid valve 82, the third solenoid valve 83, and the fourth solenoid valve 84 are closed, i.e., all inlet and outlet solenoid valves of the gas-liquid separator 2 are closed, keeping the gas-liquid separator 2 in a sealed space to prevent refrigerant migration and thus minimizing the possibility of liquid slugging in the compressor 1 during the next startup, thereby ensuring the safe operation of the compressor 1.

[0055] Specifically, the liquid level height at the oil return hole in the gas-liquid separator 2 is A mm.

[0056] Specifically, the first set value h of the liquid level 设1 The range of values ​​for is not specifically limited.

[0057] More specifically, the first set value h of the liquid level 设1 The value range is (A+40, A+60], and the first set value of the liquid level h 设1 The first set value of the liquid level h can be any value from (A+40, A+60). 设1 The unit is mm.

[0058] Preferably, in this embodiment, the first set value h of the liquid level 设1 The value is A+50mm.

[0059] Specifically, the second set value h of the liquid level 设2 The range of values ​​for is not specifically limited.

[0060] More specifically, the second set value h of the liquid level 设2The value range is [A+20, A+40), and the second set value of the liquid level h 设2 The second set value of the liquid level h can be any value from [A+20, A+40). 设2 The unit is mm.

[0061] Preferably, in this embodiment, the second set value h of the liquid level 设2 The value is A+30mm.

[0062] Specifically, the first rate is not specifically limited.

[0063] More specifically, in this embodiment, the first rate is 1 Hz / s.

[0064] The first rate is 1 Hz / s. Compressor 1 increases the target frequency by 10 Hz every 10 seconds. After reaching the target operating frequency, it stops increasing. Similar to the normal start-up mode, the frequency of compressor 1 slowly increases to the target frequency.

[0065] Specifically, the second rate is not specifically limited.

[0066] More specifically, in this embodiment, the second rate is 2 Hz / s.

[0067] The second rate is 2 Hz / s. Compressor 1 increases the target frequency by 10 Hz every 5 seconds. After reaching the target operating frequency, it stops increasing, shortening the frequency change cycle of compressor 1. The frequency of compressor 1 rises rapidly to the target frequency.

[0068] More specifically, in this embodiment, in the liquid collection mode, if it is in cooling mode, the four-way valve 5 switches, and the system operates in heating mode. The target operating frequency of compressor 1 is set to B (generally the highest frequency * 40%). After compressor 1 reaches the set target operating frequency, the first solenoid valve 81 and the fourth solenoid valve 84 are opened, and the second solenoid valve 82 and the third solenoid valve 83 are closed. At this time, the high-pressure refrigerant gas at the outlet of compressor 1 enters the gas-liquid separator 2, and the refrigerant liquid in the gas-liquid separator 2 is introduced from the bottom of the gas-liquid separator 2 through the fourth solenoid valve 84 into the liquid receiver 4 for storage. If there is a lot of refrigerant in the liquid receiver 4, the excess refrigerant liquid enters the indoor heat exchanger of the indoor unit 7 for storage.

[0069] The control method for preventing compressor start-up liquid return in this embodiment is interconnected with and inseparable from the system for preventing compressor start-up liquid return in a refrigeration air conditioner. The indoor unit 7, compressor 1, gas-liquid separator 2, oil separator 3, liquid receiver 4, outdoor heat exchanger 6, four-way valve 5, first solenoid valve 81, second solenoid valve 82, third solenoid valve 83, fourth solenoid valve 84, and electronic expansion valve 85 are interconnected and inseparable, playing multiple roles.

[0070] First, the system can start in different modes according to different liquid levels when it is turned on. On the one hand, it can avoid liquid return to compressor 1 during startup and prevent damage to compressor 1; on the other hand, it can quickly increase the starting frequency of compressor 1, improve the initial air conditioning cooling and heating effect, and improve comfort.

[0071] 2. When the system is shut down, if the liquid level height h2 ≥ the first set value h 设1 Then, it enters the liquid collection mode. By opening the first solenoid valve 81 and the fourth solenoid valve 84, and closing the second solenoid valve 82 and the third solenoid valve 83, the high-pressure refrigerant gas at the outlet of compressor 1 enters the gas-liquid separator 2. Using the high pressure established by compressor 1, the liquid refrigerant in the gas-liquid separator 2 is introduced into the liquid receiver 4 for storage. This can minimize the occurrence of liquid slugging in compressor 1 during the next startup and ensure the safe operation of compressor 1.

[0072] 3. Before the system stops running, close the first solenoid valve 81, the second solenoid valve 82, the third solenoid valve 83 and the fourth solenoid valve 84, that is, close all the inlet and outlet solenoid valves of the gas-liquid separator 2, so that the gas-liquid separator 2 is in a closed space to prevent refrigerant from migrating in, thereby minimizing the occurrence of liquid slugging in the compressor 1 during the next start-up, and thus ensuring the safe operation of the compressor 1.

[0073] While the present invention has been disclosed above, it is not limited thereto. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A control method for preventing liquid return during compressor startup in a refrigeration air conditioner, characterized in that, The refrigeration and air conditioning system that prevents the compressor from starting and causing liquid return includes an indoor unit (7), a compressor (1), a gas-liquid separator (2), an oil separator (3), a liquid receiver (4), an outdoor heat exchanger (6), a four-way valve (5), and an electronic expansion valve (85) connected in a circulation loop via pipes. A liquid receiver (4) is installed between the indoor unit (7) and the outdoor unit. The first port (41) of the liquid receiver (4) is connected to the electronic expansion valve (85), the second port (42) of the liquid receiver (4) is connected to the indoor unit (7), and the third port (43) of the liquid receiver (4) is connected to the gas-liquid separator (2). The refrigeration and air conditioning system that prevents the compressor from starting and causing liquid return can start in different modes according to different liquid levels when it is turned on. A first return pipe (22) is provided on the gas-liquid separator (2), and the gas-liquid separator (2) is connected to the four-way valve (5) through the first return pipe (22). A second solenoid valve (82) is provided on the first return pipe (22). A second return pipe (23) is provided on the gas-liquid separator (2), and the gas-liquid separator (2) is connected to the compressor (1) through the second return pipe (23). A third solenoid valve (83) is provided on the second return pipe (23). A first branch (24) is provided on the first return pipe (22), one end of which is connected between the oil separator (3) and the four-way valve (5). The other end of which is connected between the gas-liquid separator (2) and the second solenoid valve (82). A first solenoid valve (81) is provided on the first branch (24). A fourth solenoid valve (84) is provided between the gas-liquid separator (2) and the liquid reservoir (4). The control method for preventing the compressor from starting and returning liquid in a refrigeration air conditioner includes the following steps: When a refrigeration air conditioning system that prevents the compressor from returning liquid is started: upon receiving the start command, the liquid level height h1 in the gas-liquid separator (2) is obtained; it is then determined whether the liquid level height h1 is greater than or equal to the first set value h1. 设1 If yes, then start in the first mode, and the frequency of the compressor (1) rises to the target frequency at the first rate; if no, then start in the second mode, and the frequency of the compressor (1) rises to the target frequency at the second rate; the second rate is greater than the first rate. When the refrigeration air conditioning system that prevents the compressor from starting and returning liquid is shut down: after receiving the shutdown command, obtain the liquid level height h2 in the gas-liquid separator (2); if the liquid level height h2 ≥ the first set value of liquid level h 设1 Then, it enters the liquid collection mode and introduces the refrigerant liquid in the gas-liquid separator (2) into the liquid receiver (4) for storage. After entering the liquid collection mode, the following steps are included: the refrigeration air conditioning system that prevents the compressor from starting to return liquid is operated in heating mode. After the compressor (1) reaches the target frequency, the first solenoid valve (81) and the fourth solenoid valve (84) are opened, and the second solenoid valve (82) and the third solenoid valve (83) are closed. The refrigerant liquid in the gas-liquid separator (2) is introduced from the bottom of the gas-liquid separator (2) through the fourth solenoid valve (84) into the liquid receiver (4) for storage.

2. The control method for preventing liquid return during compressor startup in a refrigeration air conditioner according to claim 1, characterized in that, A liquid level sensor (21) is installed inside the gas-liquid separator (2), and the liquid level sensor (21) is used to detect the liquid level height inside the gas-liquid separator (2).

3. The control method for preventing liquid return during compressor startup in a refrigeration air conditioner according to claim 1, characterized in that, An oil return hole is provided inside the gas-liquid separator (2).

4. The control method for preventing liquid return during compressor startup in a refrigeration air conditioner according to claim 1, characterized in that, The refrigeration air conditioning system that prevents the compressor from starting and returning liquid also includes the following steps when shutting down: If the liquid level height h2 < the second set value h 设2 If the first solenoid valve (81), the second solenoid valve (82), the third solenoid valve (83), and the fourth solenoid valve (84) are closed.

5. The control method for preventing liquid return during compressor startup in a refrigeration air conditioner according to claim 1, characterized in that, The liquid level height at the oil return hole in the gas-liquid separator (2) is A mm, and the first set value of the liquid level is h. 设1 The value range is (A+40, A+60], and the first set value of the liquid level h 设1 The unit is mm.

6. The control method for preventing liquid return during compressor startup in a refrigeration air conditioner according to claim 4, characterized in that, The second set value of the liquid level h 设2 The value range is [A+20, A+40), and the second set value h of the liquid level is... 设2 The unit is mm.

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