Liquid return prevention control method of air conditioning system and air conditioning system

Abstract

The invention discloses a liquid return prevention control method of an air conditioning system and the air conditioning system. The air conditioning system at least comprises a preheating branch and an air suction branch which are connected between a compressor and a vapor-liquid separator. The liquid return prevention control method comprises the steps that operation parameters of the air conditioning system are detected; judging whether the air conditioning system has a liquid impact risk or not according to the operation parameters; and the conduction state of the preheating branch and the air suction branch is controlled according to whether the air conditioning system has the liquid impact risk or not. Compared with the prior art, the refrigerant in the air suction pipe can be heated in time, the liquid refrigerant is changed into the gaseous refrigerant, and the risk of liquid impact is avoided.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of air conditioners, and in particular to a back-liquid prevention control method of an air conditioning system and the air conditioning system. BACKGROUND

[0002] The compressor of an air conditioning system is easily damaged in a liquid strike state, so most air conditioning systems are provided with a vapor-liquid separator to separate liquid refrigerant from gaseous refrigerant to avoid liquid refrigerant entering the compressor to cause liquid strike.

[0003] The conventional vapor-liquid separator has low separation efficiency, especially at low temperature, and the separation efficiency is very low. In addition, the vapor-liquid separator has a limited volume (a large vapor-liquid separator not only has high cost, but also affects system reliability), which further aggravates the risk of back-liquid. When heating is run in an ultra-low temperature outdoor environment, a large amount of liquid refrigerant accumulates in the vapor-liquid separator. Due to the low ambient temperature, the refrigerant is difficult to circulate in a short time. The system has low exhaust superheat for a long time after the compressor starts. At this time, not only is liquid strike likely to occur, but also poor lubrication of the lubricating oil can cause damage to the compressor.

[0004] In addition, when heating is run, the outdoor heat exchanger is constantly frosting, and the poor outdoor heat exchanger can further aggravate the accumulation of liquid refrigerant in the vapor-liquid separator, and thus cause a large amount of back-liquid to impact the compressor.

[0005] The accumulation of refrigerant in the vapor-liquid separator has been solved by many technologies in the industry, but the problem is not perfectly solved. The back-liquid refrigerant cannot be heated to the target problem, the amount and flow rate of the heated refrigerant cannot be controlled, resulting in excessive heating, which not only causes capacity loss and increased power consumption, but also causes excessive suction superheat, which also affects the reliability of the compressor.

[0006] The patent ZL202010120640.1 also proposes a new solution to heat the refrigerant in the vapor-liquid separator from the high-pressure side due to the high-temperature gas, but the refrigerant has not established a superheat degree when the compressor is started, and the temperature is relatively low. Even the temperature of the refrigerant gas discharged by the compressor is relatively low, which cannot efficiently heat the refrigerant in the vapor-liquid separator. In addition, this bypass method also affects the indoor heating effect.

[0007] Therefore, how to design a back-liquid prevention control method of an air conditioning system and the air conditioning system to avoid the risk of liquid strike of the compressor is a technical problem to be solved in the industry. SUMMARY

[0008] In view of the low processing efficiency of the vapor-liquid separator for back-liquid refrigerant and the risk of liquid strike of the compressor in the prior art, the present application provides a back-liquid prevention control method of an air conditioning system and the air conditioning system.

[0009] The technical scheme of the present application is to provide a liquid return prevention control method for an air conditioning system, wherein the air conditioning system comprises at least a preheating branch and a suction branch connected between a compressor and a vapor-liquid separator;

[0010] The liquid return prevention control method comprises detecting an operating parameter of the air conditioning system.

[0011] According to the operating parameter, it is determined whether the air conditioning system has a risk of liquid strike.

[0012] According to whether the air conditioning system has the risk of liquid strike, the conducting state of the preheating branch and the suction branch is controlled.

[0013] Further, the detecting of the operating parameter of the air conditioning system comprises:

[0014] determining a working mode of the air conditioning system.

[0015] When the air conditioning system is in a cooling mode, the suction superheat of the compressor in the air conditioning system is detected.

[0016] Further, according to the operating parameter, it is determined whether the air conditioning system has the risk of liquid strike, which comprises:

[0017] When the air conditioning system is in the cooling mode, it is determined whether the suction superheat is higher than a first threshold temperature.

[0018] If not, it is determined that the air conditioning system has the risk of liquid strike.

[0019] Further, the air conditioning system further comprises an electric heating belt arranged on the compressor and the vapor-liquid separator.

[0020] According to whether the air conditioning system has the risk of liquid strike, the conducting state of the preheating branch and the suction branch is controlled, which comprises:

[0021] When it is determined that the air conditioning system has the risk of liquid strike, the suction branch is conducted, and the electric heating belt arranged on the compressor and the vapor-liquid separator is controlled to be turned on.

[0022] Further, the detecting of the operating parameter of the air conditioning system comprises:

[0023] determining a working mode of the air conditioning system.

[0024] When the air conditioning system is in a heating mode, the ambient temperature of the air conditioning system and the suction superheat of the compressor in the air conditioning system are detected.

[0025] Further, according to the operating parameter, it is determined whether the air conditioning system has the risk of liquid strike, which comprises:

[0026] determining whether the ambient temperature of the air conditioning system is lower than a second threshold temperature;

[0027] If yes, it is determined that the air conditioning system has a risk of liquid strike.

[0028] Further, a suction heating device for preheating is arranged on the preheating branch, and the suction heating device at least comprises a heating cavity, an electric heating wire, and a heat preservation material.

[0029] When the ambient temperature of the air conditioning system is lower than the second threshold temperature, the conduction states of the preheating branch and the suction branch are controlled according to whether the air conditioning system has a risk of liquid strike, comprising:

[0030] The cavity temperature of the heating cavity is detected in real time.

[0031] The difference between the cavity temperature and the ambient temperature of the air conditioning system is calculated.

[0032] When the difference is greater than a third threshold temperature, the preheating branch is turned on.

[0033] Further, whether the air conditioning system has a risk of liquid strike is determined according to the operating parameter, comprising:

[0034] Determining whether the ambient temperature of the air conditioning system is lower than a second threshold temperature.

[0035] If no, it is determined that the air conditioning system has a risk of liquid strike when the suction superheat is higher than a first threshold temperature.

[0036] The application further provides an air conditioning system adopting the anti-liquid-return control method of the air conditioning system, and the air conditioning system at least comprises a preheating branch and a suction branch connected between a compressor and a vapor-liquid separator.

[0037] The air conditioning system further comprises a detection device for detecting operating parameters, and a determination device for determining whether the air conditioning system has a risk of liquid strike according to the operating parameters.

[0038] The air conditioning system switches on any one of the preheating branch and the suction branch according to whether the air conditioning system has a risk of liquid strike.

[0039] Further, the air conditioning system further comprises a first suction electromagnetic valve arranged in the preheating branch, and a second suction electromagnetic valve arranged in the suction branch.

[0040] The air conditioning system switches on the preheating branch and the suction branch by controlling the conduction states of the first suction electromagnetic valve and the second suction electromagnetic valve.

[0041] Compared with the prior art, the present application has at least the following beneficial effects:

[0042] The present application adds a preheating branch to the suction branch between the vapor-liquid separator and the compressor of the air conditioning system, and the vapor-liquid separator and the compressor of the air conditioning system are equipped with an electric heating belt. When the compressor has a risk of liquid strike, the preheating branch can be turned on, or the electric heating belt is turned on to heat the refrigerant, thereby shortening the heating time, assisting the conversion of liquid refrigerant into gas, and avoiding the problem of liquid strike of the compressor. BRIEF DESCRIPTION OF DRAWINGS

[0043] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0044] Figure 1 The schematic diagram of the air conditioning system in the present application;

[0045] Figure 2 The overall control logic diagram of the anti-liquid return control method in the present application;

[0046] Figure 3 The control flow chart in the refrigeration mode in the present application;

[0047] Figure 4 The control flow chart in the heating mode in the present application. DETAILED DESCRIPTION

[0048] In order to make the technical problems to be solved by the present application, the technical solutions and the beneficial effects more clear and explicit, the present application will be further described in detail in combination with the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application, and are not used to limit the present application.

[0049] Therefore, one feature indicated in the specification will be used to explain one feature of one embodiment of the present application, and it is not implied that each embodiment of the present application must have the explained feature. In addition, it should be noted that the present specification describes many features. Although some features can be combined together to show possible system designs, these features can also be used in other combinations which are not explicitly described. Therefore, unless otherwise specified, the described combinations are not intended to be limiting.

[0050] The principles and structures of the present application will be described in detail in combination with the drawings and embodiments.

[0051] The compressor of an air conditioning system is easily damaged in a liquid knock state, so most air conditioning systems are provided with a gas-liquid separator to separate liquid refrigerant from gaseous refrigerant to avoid liquid knock caused by liquid refrigerant entering the compressor. The conventional gas-liquid separator has low separation efficiency, especially at low temperature, and the limited volume of the gas-liquid separator (a too large gas-liquid separator not only has high cost but also affects system reliability) further increases the risk of liquid return.

[0052] Based on the above problems, the present application provides a control method for preventing liquid return of an air conditioning system, wherein the air conditioning system at least comprises a preheating branch connected between a compressor and a gas-liquid separator.

[0053] Please refer to Figure 1 which is a structural schematic diagram of the air conditioning system in the present application, wherein the air conditioning system has a gas-liquid separator (i.e. the gas separation in the attached Figure 1 and a compressor, the gas-liquid separator is used to separate gaseous refrigerant and liquid refrigerant and deliver the gaseous refrigerant to the compressor for refrigeration.

[0054] The separation efficiency of the gas-liquid separator for gaseous refrigerant and liquid refrigerant is very low, especially in a low temperature environment, which leads to the risk of liquid refrigerant entering the compressor, i.e. the risk of liquid knock.

[0055] In the present application, two branches for passing refrigerant are provided between the gas-liquid separator and the compressor, i.e. a suction branch and a preheating branch, and a suction heating device is arranged on the preheating branch to heat the refrigerant in the branch, so that the liquid refrigerant is vaporized into gaseous refrigerant to avoid entering the compressor.

[0056] In addition, an electric heating belt is also arranged on the gas-liquid separator and the compressor of the air conditioning system, which can also heat the refrigerant to vaporize the liquid refrigerant into gaseous refrigerant to avoid entering the compressor.

[0057] In the operation of the air conditioning system, there are many working conditions, generally the risk of liquid knock is low when the external environment temperature is high, and the risk of liquid knock is high when the external environment temperature is low. The above-mentioned preheating branch and electric heating belt are used to heat the liquid refrigerant to avoid the risk of liquid knock. However, if the branch is used for a long time, the problem of suction overheating of the compressor may occur, which also damages the compressor.

[0058] Therefore, based on the above-mentioned arrangement of the air conditioning system, the control idea is that when the air conditioning system has the risk of liquid knock, the above-mentioned preheating branch is turned on or the electric heating belt is turned on, and vice versa, when the air conditioning system does not have the risk of liquid knock, the above-mentioned suction branch is turned on.

[0059] Based on this, please refer toFigure 2 The anti-liquid-return control method provided by the application comprises:

[0060] detecting an operating parameter of the air conditioning system;

[0061] judging whether the air conditioning system has a liquid strike risk according to the operating parameter;

[0062] controlling the conduction state of the preheating branch and the suction branch according to whether the air conditioning system has the liquid strike risk.

[0063] In the anti-liquid-return control method provided by the application, the preheating branch is turned on or the electric heating belt is turned on when the compressor has a liquid strike risk, and the suction branch is turned on, so that the above beneficial effects are achieved: the preheating branch is turned on or the electric heating belt is turned on to heat the refrigerant, the heating time is shortened, the liquid refrigerant is converted into gaseous refrigerant, and the liquid strike problem of the compressor is avoided.

[0064] As described above, the air conditioning system has many operating conditions, and the possibility of the compressor having a liquid strike risk is different under different operating conditions, so the judgment of whether the air conditioning system has a liquid strike risk according to the operating parameter in the application needs to be made according to different operating conditions of the air conditioning system.

[0065] The air conditioning system generally has two operating modes, namely, a cooling mode and a heating mode, and the judgment of whether the air conditioning system has a liquid strike risk is also based on the two modes.

[0066] Therefore, the detection of the operating parameter of the air conditioning system comprises:

[0067] judging the operating mode of the air conditioning system;

[0068] when the air conditioning system is in the cooling mode, detecting the suction superheat of the compressor in the air conditioning system.

[0069] For the cooling mode, the compressor generally has a liquid strike risk only when it is started under the condition that the external environment temperature is high, and the compressor generally does not have a liquid strike risk after it is stabilized because the high external environment temperature can also help the refrigerant to become gaseous, so the suction superheat of the compressor is mainly used to judge whether the compressor has a liquid strike risk under this condition.

[0070] Whether the compressor sucks liquid refrigerant, gaseous refrigerant or mixed refrigerant can be judged by the suction superheat.

[0071] If the suction temperature minus the module low pressure (the saturation pressure corresponding to the evaporation temperature) is less than 0, the liquid refrigerant is attached to the pipeline to evaporate, resulting in a lower pipe temperature than the surface temperature of the saturation temperature, and there may be a risk of liquid strike. On the contrary, if the suction temperature minus the module low pressure is greater than 0, it indicates that the refrigerant is heated to have a superheat degree, and its temperature is greater than the saturation pressure value, and there is no risk of liquid strike.

[0072] That is, the present application can determine whether the compressor has a liquid strike risk by using the suction superheat degree. Therefore, in the above refrigeration mode, the operating parameter of the air conditioning system detected in the present application is the suction superheat degree.

[0073] In this control scheme, the present application can accurately determine whether there is a risk of liquid strike when the air conditioning system is in the refrigeration mode.

[0074] As described above, the suction superheat degree can be used to determine whether the air conditioning system has a liquid strike risk. The specific principle is that if the suction superheat degree is high, it is determined that the air conditioning system does not have a liquid strike risk, and vice versa.

[0075] Based on this principle, the present application determines whether the air conditioning system has a liquid strike risk according to the operating parameter when the air conditioning system is in the refrigeration mode, comprising:

[0076] When the air conditioning system is in the refrigeration mode, it is determined whether the suction superheat degree is higher than the first threshold temperature.

[0077] If not, it is determined that the air conditioning system has a liquid strike risk.

[0078] In the operation process of the air conditioning system, the suction superheat degree is generally controlled at 2-10℃. In the present application, 2℃ is used as the first threshold temperature for judgment. If the suction superheat degree of the air conditioning system is greater than 2℃, it is determined that the air conditioning system does not have a liquid strike risk, and vice versa.

[0079] It should be noted that 2℃ is only a setting in a preferred embodiment of the present application. In other embodiments of the present application, the above-mentioned first threshold temperature can also be adjusted according to the actual operating conditions of the air conditioning system.

[0080] That is, based on the above judgment logic, the present application provides an accurate judgment logic for the liquid strike risk of the air conditioning system, which can determine whether the air conditioning system has a liquid strike risk, and further provides a related basis for the control of the suction branch and the preheating branch. By turning on the preheating branch or starting the electric heating belt when the air conditioning system has a liquid strike risk, the problem of liquid strike of the compressor can be avoided.

[0081] Specifically, in the refrigeration mode, the working environment of the air conditioning system is generally high temperature, at this time only the electric heating belt on the vapor-liquid separator needs to be turned on to achieve auxiliary heating for the liquid refrigerant, that is, at this time, the on-off state of the preheating branch and the suction branch is controlled according to whether the air conditioning system has a liquid strike risk, including:

[0082] When it is determined that the air conditioning system has a liquid strike risk, the suction branch is turned on, and the compressor and the electric heating belt on the vapor-liquid separator are turned on.

[0083] Based on the control logic, the liquid strike problem of the compressor can be avoided, and the preheating branch does not need to be turned on, and the suction overheat problem of the compressor is also avoided.

[0084] Please refer to Figure 3 , which is the control flowchart of the present application in the refrigeration mode. When the air conditioning system is started, the running parameters are detected by the built-in temperature sensing bag, sensor, etc., and the judgment is made.

[0085] Then, according to the built-in program of the air conditioning system, if the suction overheat is higher than 2℃, it is determined that it is not a liquid return state, that is, the vapor-liquid separator does not carry a large amount of liquid refrigerant to the suction port of the compressor, at this time the compressor has no liquid strike risk and does not need special treatment, and the control is carried out according to the conventional control method of the air conditioning system, at this time the electric heating belt of the compressor, the electric heating belt of the vapor-liquid separator, and the electric heating of the suction device do not need to be turned on, and the refrigerant goes through the suction branch.

[0086] Please refer to Figure 1 , in the present application, the preheating branch is provided with the suction solenoid valve 1, and the suction branch is provided with the suction solenoid valve 2, the air conditioning system can control the on-off state of the suction solenoid valve 1 and the suction solenoid valve 2, and then control whether the suction branch or the preheating branch is turned on.

[0087] Here, the Figure 3 in the present application, when the suction overheat is higher than 2℃, the suction solenoid valve 1 is closed and the suction solenoid valve 2 is opened, that is, the suction branch is turned on.

[0088] On the contrary, when the suction overheat is less than 2℃, it is determined that it is a liquid return state, that is, there is liquid refrigerant in the suction pipe of the compressor, which will cause damage to the compressor if sucked into the compressor. At this time, because the outdoor temperature is not particularly low in the refrigeration mode, only the electric heating belt of the compressor and the electric heating belt of the vapor-liquid separator need to be turned on to achieve the temperature rise of the liquid refrigerant, and the electric heating of the suction device does not need to be turned on, and the refrigerant goes through the suction branch.

[0089] Here, the Figure 3When the suction superheat is higher than 2℃, the suction electromagnetic valve 1 is controlled to be closed, and the suction electromagnetic valve 2 is controlled to be opened, that is, the suction branch is turned on.

[0090] Further, the method for detecting the operation parameters of the air conditioning system further comprises:

[0091] judging the working mode of the air conditioning system;

[0092] When the air conditioning system is in the heating mode, detecting the ambient temperature of the air conditioning system and the suction superheat of the compressor in the air conditioning system.

[0093] Compared with the refrigeration mode, the heating mode of the air conditioning system is generally operated in the case that the outdoor ambient temperature is low, and at this time, the liquid strike phenomenon is most likely to occur. Since the ambient temperature of different users when starting the refrigeration mode is different, the second threshold temperature is set according to whether the liquid strike phenomenon is likely to occur in the present application. If the ambient temperature of the air conditioning system is lower than the second threshold temperature, it can be determined that the air conditioning system is in an ultra-low temperature working condition at this time, and the risk of liquid strike is highest at this time. If the ambient temperature of the air conditioning system is higher than the second threshold temperature, the ambient temperature at this time is relatively high, and the suction superheat can be used to determine whether the compressor is at risk of liquid strike.

[0094] Therefore, in the heating mode of the present application, the operation parameters to be detected include the ambient temperature of the air conditioning system and the suction superheat of the compressor. Through the detection method, the present application can accurately determine whether the air conditioning system is at risk of liquid strike when the air conditioning system is in the heating mode, and then control the conduction state of the preheating branch to avoid the liquid strike problem of the compressor.

[0095] As described above, after the second threshold temperature is set in the present application, the air conditioning system is determined to be in an ultra-low temperature state when the second threshold temperature is lower than the second threshold temperature, and the risk of liquid strike of the compressor is highest at this time. Therefore, in the heating mode of the present application, whether the air conditioning system is at risk of liquid strike can be determined according to the operation parameters, which can include:

[0096] judging whether the ambient temperature of the air conditioning system is lower than the second threshold temperature;

[0097] If yes, it is determined that the air conditioning system is at risk of liquid strike.

[0098] That is, based on the above judgment logic, the present application provides an accurate judgment logic for the air conditioning system at risk of liquid strike, which can determine whether the air conditioning system is at risk of liquid strike, and further provides a related basis for the control of the suction branch and the preheating branch. By turning on the preheating branch or starting the electric heating belt when the air conditioning system is at risk of liquid strike, the liquid strike problem of the compressor can be avoided.

[0099] In a preferred embodiment of the present application, the second threshold temperature is set to -5℃, and if the temperature is lower than the second threshold temperature, it is determined that the air conditioning system is in an ultra-low temperature working condition, and there is a high risk of liquid strike.

[0100] Further, the present application is provided with an air suction heating device for preheating on the preheating branch, which at least includes a heating cavity, an electric heating wire, and a heat preservation material.

[0101] Please refer to Figure 1 , the Figure 1 air suction electromagnetic valve 1 is provided with an air suction heating device on one way, and the electric heating is an electric heating wire. The part where the heat preservation material and the electric heating wire are placed is a heating cavity. In the present application, a heating cavity temperature sensing bag is also provided for detecting the temperature in the heating cavity, which is mainly used to determine the time when the preheating branch is turned on according to the temperature of the heating cavity. The specific control logic is as follows:

[0102] When the ambient temperature of the air conditioning system is lower than the second threshold temperature, the on-off state of the preheating branch and the air suction branch is controlled according to whether there is a risk of liquid strike in the air conditioning system, including:

[0103] Real-time detection of the cavity temperature of the heating cavity;

[0104] Calculate the difference between the cavity temperature and the ambient temperature of the air conditioning system;

[0105] When the difference is greater than the third threshold temperature, the preheating branch is turned on.

[0106] Here, the preheating branch is turned on when the difference is greater than the third threshold temperature, because the heating cavity needs time to heat up, and only when the temperature in the heating cavity is higher than the ambient temperature by the third threshold temperature, can it play the role of auxiliary heating for the liquid refrigerant, making it into gaseous refrigerant. If the preheating branch is turned on too early, the temperature in the heating cavity has not risen, and at this time, there will still be a lot of liquid refrigerant entering the compressor, which will cause a risk of liquid strike.

[0107] That is, by turning on the preheating branch and controlling the on-off time of the preheating branch by detecting the cavity temperature of the heating cavity, the present application can completely avoid the problem of liquid strike in the compressor.

[0108] In a preferred embodiment of the present application, the third threshold temperature is set to 10℃.

[0109] Further, when the preheating branch is turned on, the heating time is also detected. If the heating time reaches 5min and the difference is still greater than the third threshold temperature, the preheating branch will also be turned on at this time.

[0110] The on time is set mainly in consideration of special situations or temperature sensing bag failure, at which time if the machine is not started all the time, the user experience will be affected.

[0111] The control part considers that the air conditioning system is in a heating mode, and the ambient temperature of the air conditioning system is lower than the second threshold temperature, and the ambient temperature of the air conditioning system is higher than the second threshold temperature, at which time the suction gas superheat degree is still used as the main judgment standard for whether the compressor exists liquid knock risk, and in this case:

[0112] The air conditioning system is judged whether to exist liquid knock risk according to the operation parameters, including:

[0113] The ambient temperature of the air conditioning system is judged whether to be lower than the second threshold temperature;

[0114] If not, when the suction gas superheat degree is higher than the first threshold temperature, it is determined that the air conditioning system exists liquid knock risk.

[0115] At this time, the control on-off logic of the suction branch and the preheating branch is consistent with that in the cooling mode, which controls the on-off state of the preheating branch and the suction branch according to whether the air conditioning system exists liquid knock risk, including:

[0116] When it is determined that the air conditioning system exists liquid knock risk, the suction branch is turned on, and the electric heating belt on the compressor and the vapor-liquid separator is turned on.

[0117] Based on the above judgment logic, the present application provides an accurate judgment logic for the air conditioning system existing liquid knock risk, which can determine whether the air conditioning system exists liquid knock risk, and further provides a related basis for the control of the suction branch and the preheating branch. By turning on the preheating branch or turning on the electric heating belt when the air conditioning system exists liquid knock risk, the problem of liquid knock of the compressor can be avoided.

[0118] Please refer to Figure 4 which is the control flow chart of the present application in the cooling mode. When the air conditioning system is started, the operation parameters are detected by the built-in temperature sensing bag, sensor and the like, and the judgment is made.

[0119] It first detects the outdoor ambient temperature of the air conditioning system, and then judges whether the outdoor ambient temperature is less than-5℃;

[0120] If yes, the preheating control is started, the suction device electric heating (i.e. the electric heating wire in the foregoing) is turned on before starting, and then the compressor is allowed to start when the cavity temperature Tr>Tenv+10℃, otherwise, the heating continues, and the compressor is not started, if the heating time reaches 5min and the target temperature is still not reached, the starting is also allowed. Here, Tr is the cavity temperature, Tenv is the ambient temperature, and 10℃ is the third threshold temperature.

[0121] At this time, the electric heating belts in the compressor and the vapor-liquid separator are controlled to be turned on, and the electric heating in the suction heating device is turned on at the same time.

[0122] Here, the attachment Figure 4 The suction solenoid valve 1 is controlled to be opened, and the suction solenoid valve 2 is controlled to be closed, that is, the preheating branch is turned on.

[0123] As described above, if the preheating branch is used for a long time, the problem of overheating of the suction gas of the compressor may occur, and the compressor may also be damaged. Therefore, the present application further detects the suction gas overheating degree of the air conditioning system under the control logic. When the suction gas overheating degree of the air conditioning system is higher than the first threshold temperature, that is, 2℃, which is the first threshold temperature, at this time, the control is consistent with that in the refrigeration mode. The heating demand of the refrigerant can be met by turning on the electric heating belts of the compressor and the vapor-liquid separator, that is, at this time, only the electric heating belts of the compressor and the vapor-liquid separator need to be turned on to realize the temperature rise of the liquid refrigerant, and the electric heating of the suction device does not need to be turned on, and the refrigerant can pass through the suction branch.

[0124] If the outdoor environment temperature at this time is greater than -5℃, the control is directly consistent with that in the heating mode,

[0125] The air conditioning system detects the operating parameters through the built-in temperature sensing bag, sensor and the like, and judges.

[0126] Then, according to the built-in program of the air conditioning system, if the suction gas overheating degree is higher than 2℃, it is determined that it is a non-liquid return state, that is, the vapor-liquid separator does not carry a large amount of liquid refrigerant to the suction port of the compressor, at this time, the compressor has no risk of liquid hammering, and no special treatment is needed. According to the conventional control method of the air conditioning system, the electric heating belts of the compressor, the electric heating belts of the vapor-liquid separator, the electric heating of the suction device and the like do not need to be turned on, and the refrigerant can pass through the suction branch.

[0127] On the contrary, when the suction gas overheating degree is less than 2℃, it is determined that it is a liquid return state, that is, there is liquid refrigerant in the suction pipe of the compressor, which may cause damage to the compressor if sucked into the compressor. At this time, only the electric heating belts of the compressor and the vapor-liquid separator need to be turned on to realize the temperature rise of the liquid refrigerant, and the electric heating of the suction device does not need to be turned on, and the refrigerant can pass through the suction branch.

[0128] Based on the above anti-liquid return control method, the present application further provides an air conditioning system, which comprises a preheating branch and a suction branch connected between the compressor and the vapor-liquid separator;

[0129] The air conditioning system further comprises detection devices for detecting operation parameters, and judgment devices for judging whether the air conditioning system has a risk of liquid strike according to the operation parameters.

[0130] The air conditioning system switches any one of the preheating branch and the suction branch to be conducted according to whether there is a risk of liquid strike.

[0131] Based on the air conditioning system, the above-mentioned anti-liquid return control method can be implemented, and the preheating branch can be conducted when the compressor has a risk of liquid strike, or the electric heating belt is turned on to heat the refrigerant, the heating time is shortened, the liquid refrigerant is converted into gaseous refrigerant, and the problem of liquid strike of the compressor is avoided.

[0132] Please refer to Figure 1 The air conditioning system further comprises a first suction solenoid valve arranged in the preheating branch, and a second suction solenoid valve arranged in the suction branch.

[0133] The air conditioning system switches the preheating branch and the suction branch to be conducted by controlling the conduction states of the first suction solenoid valve and the second suction solenoid valve.

[0134] The first suction solenoid valve is the suction solenoid valve 1 in the attached Figure 1 The second suction solenoid valve is the suction solenoid valve 2 in the attached Figure 1 The first suction solenoid valve is used for control, which has the advantages of fast action, small power, light and compact appearance, high control precision, etc.

[0135] Compared with the prior art, the present application has at least the following advantages:

[0136] The present application adds a preheating branch to the suction branch between the vapor-liquid separator and the compressor of the air conditioning system, and the vapor-liquid separator and the compressor of the air conditioning system are equipped with an electric heating belt. When the compressor has a risk of liquid strike, the preheating branch can be conducted, or the electric heating belt is turned on to heat the refrigerant, the heating time is shortened, the liquid refrigerant is converted into gaseous refrigerant, and the problem of liquid strike of the compressor is avoided.

Claims

1. A liquid backflow prevention control method for an air conditioning system, characterized in that: The air conditioning system at least includes a preheating branch and an air suction branch connected between the compressor and the vapor-liquid separator; The anti-liquid backflow control method includes: detecting operating parameters of the air conditioning system; determining whether the air conditioning system has a risk of liquid hammer according to the operating parameters; The conduction states of the preheating branch and the intake branch are controlled according to whether there is a risk of liquid hammer in the air conditioning system.

2. The liquid backflow prevention control method according to claim 1, characterized in that: Detecting the operating parameters of the air conditioning system, including: Determining the operating mode of the air conditioning system; When the air conditioning system is in a cooling mode, a suction air superheat of a compressor in the air conditioning system is detected.

3. The liquid backflow prevention control method according to claim 2, characterized in that: Determining whether the air conditioning system has a liquid hammer risk according to the operating parameters includes: When the air conditioning system is in a cooling mode, determining whether the intake air superheat is higher than a first threshold temperature; If not, it is determined that there is a risk of hydraulic shock in the air conditioning system.

4. The liquid backflow prevention control method according to claim 3, characterized in that: The air conditioning system further includes electric heating belts provided on the compressor and the vapor-liquid separator; Controlling the conduction state of the preheating branch and the intake branch according to whether there is a risk of liquid hammer in the air conditioning system includes: When it is determined that there is a risk of liquid hammer in the air-conditioning system, the air intake branch is opened, and the electric heating belts on the compressor and the vapor-liquid separator are controlled to be turned on.

5. The liquid backflow prevention control method according to claim 1, characterized in that: Detecting the operating parameters of the air conditioning system, including: Determining the operating mode of the air conditioning system; When the air conditioning system is in a heating mode, the ambient temperature of the air conditioning system and the suction superheat of the compressor in the air conditioning system are detected.

6. The liquid backflow prevention control method according to claim 5, characterized in that: Determining whether the air conditioning system has a liquid hammer risk according to the operating parameters includes: determining whether the ambient temperature of the air conditioning system is lower than a second threshold temperature; If so, it is determined that there is a risk of liquid hammer in the air conditioning system.

7. The liquid backflow prevention control method according to claim 6, characterized in that: The preheating branch is provided with an air intake heating device for preheating, and the air intake heating device at least comprises a heating chamber, an electric heating wire, and a heat insulation material; When the ambient temperature of the air-conditioning system is lower than a second threshold temperature, controlling the conduction state of the preheating branch and the intake branch according to whether there is a risk of liquid hammer in the air-conditioning system includes: detecting the chamber temperature of the heating chamber in real time; calculating a difference between the chamber temperature and an ambient temperature of the air conditioning system; When the difference is greater than a third threshold temperature, the preheating branch is turned on.

8. The liquid backflow prevention control method according to claim 5, characterized in that: Determining whether the air conditioning system has a liquid hammer risk according to the operating parameters includes: determining whether the ambient temperature of the air conditioning system is lower than a second threshold temperature; If not, it is determined that there is a hydraulic hammer risk in the air conditioning system when the intake air superheat is higher than a first threshold temperature.

9. An air conditioning system using the liquid backflow prevention control method according to any one of claims 1 to 8, characterized in that: The air conditioning system at least includes a preheating branch and an air suction branch connected between the compressor and the vapor-liquid separator; The air conditioning system further includes a detection device for detecting its operating parameters and a judgment device for judging whether the air conditioning system has a liquid hammer risk based on the operating parameters; The air conditioning system switches to conduct either the preheating branch or the intake branch according to whether there is a risk of liquid hammer.

10. The air conditioning system according to claim 9, characterized in that The air conditioning system further comprises a first air suction solenoid valve provided in the preheating branch, and a second air suction solenoid valve provided in the air suction branch; The air conditioning system switches the preheating branch and the intake branch by controlling the conduction states of the first intake solenoid valve and the second intake solenoid valve.

Images