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

Abstract

The invention relates to the technical field of air conditioners, and provides a liquid return control method and device of an air conditioner system and the air conditioner system.The air conditioner system comprises an oil return capillary tube connected between an oil return opening of an oil separator and an air suction opening of a compressor and an electromagnetic valve; the liquid return control method comprises the steps that the exhaust superheat degree of a compressor is obtained; and determining that the exhaust superheat degree of the compressor meets a first preset condition, and controlling the electromagnetic valve to execute a liquid impact prevention strategy. The oil separator can effectively prevent liquid refrigerants flowing back from the oil separator from entering the compressor, liquid impact is prevented, and therefore the purpose of protecting the compressor is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of air conditioners, and particularly to a liquid return control method, device and air conditioning system for an air conditioning system. Background Art

[0002] In related technologies, in a common multi-connected air conditioning system, an oil separator is generally configured on the exhaust side of a compressor. Through an oil return capillary tube added to the oil return port at the bottom of the oil separator, the separated oil enters the low-pressure side and is sucked back into the compressor by the compressor. Since the oil return capillary tube is always in a through state and has no control, being a pure mechanical structure, the liquid refrigerant flowing back from the oil separator enters the compressor, resulting in a liquid slugging situation, thereby damaging the compressor. Summary of the Invention

[0003] The present invention provides a liquid return control method, device and air conditioning system for an air conditioning system, which is used to solve the defect that in related technologies, the liquid refrigerant enters the compressor due to the lack of control of the oil return capillary tube in the air conditioning system, causing liquid slugging, and can effectively prevent the liquid refrigerant flowing back from the oil separator from entering the compressor, prevent liquid slugging, and thus achieve the purpose of protecting the compressor.

[0004] The present invention provides a liquid return control method for an air conditioning system. The air conditioning system includes: an oil return capillary tube and an electromagnetic valve connected between the oil return port of the oil separator and the suction port of the compressor; the liquid return control method includes:

[0005] Obtain the exhaust superheat degree of the compressor;

[0006] Determine that the exhaust superheat degree of the compressor satisfies a first preset condition, and control the electromagnetic valve to execute an anti-liquid slugging strategy.

[0007] The liquid return control method for the air conditioning system provided by the present invention, by adding an electromagnetic valve to the pipeline corresponding to the oil return capillary tube and according to the exhaust superheat degree of the compressor, can effectively control the on-off of the liquid return of the oil return capillary tube. When the exhaust superheat degree satisfies the first preset condition, it indicates that there is a risk of liquid slugging in the liquid return. At this time, control the electromagnetic valve to execute an anti-liquid slugging strategy to prevent the liquid refrigerant from entering the compressor through the oil return capillary tube, so as to prevent the occurrence of liquid slugging and protect the compressor from damage. Therefore, the present invention improves the traditional design of the oil return capillary tube without control by introducing an electromagnetic valve and intelligent control, and realizes the active management of the liquid refrigerant entering the compressor; by monitoring the exhaust superheat degree of the compressor and controlling the electromagnetic valve according to the preset conditions, it effectively prevents the liquid refrigerant flowing back from the oil separator from entering the compressor, thereby preventing the liquid slugging phenomenon and achieving the purpose of protecting the compressor.

[0008] A liquid return control method for an air conditioning system provided by the present invention, the step of determining that the exhaust superheat degree of the compressor satisfies a first preset condition and controlling the solenoid valve to execute an anti-liquid hammer strategy includes:

[0009] Determine that the exhaust superheat degree of the compressor is less than or equal to a first preset value, and control the solenoid valve to close.

[0010] The liquid return control method for the air conditioning system provided by the present invention can accurately identify the risk of liquid hammer caused by low exhaust superheat degree of the compressor and take timely measures to prevent the liquid refrigerant from entering the compressor. This intelligent control method improves the safety, stability and reliability of the air conditioning system, effectively extends the service life of the compressor and reduces the maintenance cost.

[0011] A liquid return control method for an air conditioning system provided by the present invention further includes:

[0012] Determine that the exhaust superheat degree of the compressor satisfies a second preset condition, and control the solenoid valve to execute an oil return strategy.

[0013] For the liquid return control method of the air conditioning system provided by the present invention, when the detected exhaust superheat degree of the compressor satisfies the second preset condition, it indicates that there is no liquid hammer risk and the exhaust superheat degree reaches the range suitable for oil return. At this time, controlling the solenoid valve to execute the oil return strategy can not only ensure the full evaporation of the refrigerant but also ensure that the lubricating oil can effectively return to the compressor, enabling the system to operate reliably.

[0014] A liquid return control method for an air conditioning system provided by the present invention, the step of determining that the exhaust superheat degree of the compressor satisfies a second preset condition and controlling the solenoid valve to execute an oil return strategy includes:

[0015] Determine that the duration for which the exhaust superheat degree of the compressor is greater than the first preset value reaches a set duration, and control the solenoid valve to open.

[0016] The liquid return control method for the air conditioning system provided by the present invention can, on the premise of ensuring safety, timely execute the oil return strategy, avoid the liquid hammer risk caused by too low exhaust superheat degree, and at the same time ensure that the lubricating oil can effectively return to the compressor. This intelligent control method takes into account the requirements of preventing liquid hammer and ensuring lubrication, improving the overall performance and reliability of the air conditioning system. By setting the first preset value and the set duration, the oil return timing can be controlled more precisely, optimizing the operating efficiency of the system.

[0017] A liquid return control method for an air conditioning system provided by the present invention, the step of determining that the exhaust superheat degree of the compressor satisfies a second preset condition and controlling the solenoid valve to execute an oil return strategy includes:

[0018] Determine that the exhaust superheat degree of the compressor is greater than or equal to a second preset value, and control the solenoid valve to open;

[0019] Wherein, the second preset value is greater than the first preset value.

[0020] The liquid return control method of the air conditioning system provided by the present invention can, on the premise of ensuring safety, timely execute the oil return strategy, avoid the liquid hammer risk caused by too low exhaust superheat degree, and at the same time ensure that the lubricating oil can effectively return to the compressor. Setting two preset values (the first preset value and the second preset value) can more precisely control the oil return timing, prevent liquid hammer, ensure the lubrication requirement, optimize the operation efficiency of the air conditioning system and the service life of the equipment. This intelligent control method improves the overall performance and reliability of the air conditioning system.

[0021] According to a liquid return control method of an air conditioning system provided by the present invention, the first preset value and the second preset value satisfy the following relationship:

[0022] A2 = A1 + Δ;

[0023] Wherein, A2 is the second preset value, A1 is the first preset value, and Δ is a preset safety margin.

[0024] The liquid return control method of the air conditioning system provided by the present invention, based on the relationship setting of the preset safety margin, enables the oil return control method to more precisely control the oil return timing on the premise of ensuring safety, prevent frequent opening and closing actions of liquid return, take into account the prevention of liquid hammer and the guarantee of lubrication requirements, thereby improving the overall performance and reliability of the air conditioning system.

[0025] According to a liquid return control method of an air conditioning system provided by the present invention, the step of obtaining the exhaust superheat degree of the compressor includes:

[0026] Obtain the exhaust temperature of the compressor;

[0027] Obtain the condensation pressure of the compressor;

[0028] Determine the condensation temperature according to the condensation pressure;

[0029] Determine the exhaust superheat degree of the compressor according to the exhaust temperature and the condensation temperature.

[0030] According to a liquid return control method of an air conditioning system provided by the present invention, the step of determining the exhaust superheat degree of the compressor according to the exhaust temperature and the condensation temperature includes:

[0031] TdSH = Td - Ct;

[0032] Wherein, TdSH is the exhaust superheat degree of the compressor, Td is the exhaust temperature, and Ct is the condensation temperature.

[0033] The present invention also provides a liquid return control device for an air conditioning system. The air conditioning system includes: an oil return capillary tube and a solenoid valve connected between the oil return port of an oil separator and the suction port of a compressor; the liquid return control device includes:

[0034] an acquisition module for acquiring the exhaust superheat degree of the compressor;

[0035] a control module for determining that the exhaust superheat degree of the compressor meets a first preset condition and controlling the solenoid valve to execute an anti-liquid hammer strategy.

[0036] The present invention also provides an air conditioning system, including a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the program, the above-mentioned liquid return control method for the air conditioning system is implemented. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the technical solutions in the present invention or related technologies, the following will briefly introduce the drawings required for use in the embodiments or related technology descriptions. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0038] Figure 1 is one of the structural schematic diagrams of the air conditioning system provided by the present invention;

[0039] Figure 2 is one of the flow schematic diagrams of the liquid return control method for the air conditioning system provided by the present invention;

[0040] Figure 3 is the second flow schematic diagram of the liquid return control method for the air conditioning system provided by the present invention;

[0041] Figure 4 is the third flow schematic diagram of the liquid return control method for the air conditioning system provided by the present invention;

[0042] Figure 5 is the structural schematic diagram of the liquid return control device for the air conditioning system provided by the present invention;

[0043] Figure 6 is the second structural schematic diagram of the air conditioning system provided by the present invention.

[0044] Reference numerals:

[0045] 101: oil separator; 102: compressor;

[0046] 103: oil return capillary tube; 104: solenoid valve;

[0047] 105: Exhaust gas temperature sensor; 106: Exhaust gas pressure sensor;

[0048] 501: Acquisition module; 502: Control module;

[0049] 601: Processor; 602: Communication interface;

[0050] 603: Memory; 604: Communication bus. Detailed implementation manners

[0051] To make the objectives, technical solutions and advantages of the present invention clearer, the technical solutions in the present invention will be clearly and completely described below with reference to the accompanying drawings in the present invention. Apparently, the described embodiments are some but not all of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art without making creative efforts based on the embodiments in the present invention belong to the scope of protection of the present invention.

[0052] In the description of the embodiments of the present invention, it should be noted that the terms "first", "second", etc. are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0053] In the description of the embodiments of the present invention, it should be noted that unless otherwise clearly defined and limited, the terms "connected" and "coupled" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present invention can be understood according to specific situations.

[0054] In the description of this specification, the descriptions referring to terms "one embodiment", "some embodiments", "example", "specific example", or "some examples", etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the embodiments of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, without conflict, those skilled in the art can combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0055] The following is combined with Figures 1 - 6 Describe the liquid return control method, device and air conditioning system of the air conditioning system of the present invention.

[0056] According to an embodiment of the present invention, with reference toFigure 1 As shown in the figure, the air-conditioning system provided by the present invention mainly includes an oil return capillary 103 and a solenoid valve 104 connected between the oil return port of the oil separator 101 and the suction port of the compressor 102. The newly added solenoid valve 104 can control the on-off of the liquid return of the oil return capillary 103 to prevent liquid refrigerant from entering the compressor.

[0057] The function of the oil return capillary is to transport the oil separated by the oil separator to the low-pressure side, which is sucked by the compressor for system circulation, enabling the air-conditioning system to operate reliably and for a long time. The separation efficiency of the oil separator is determined by the exhaust superheat. If the exhaust superheat is insufficient, more liquid refrigerant may return to the compressor through this oil return capillary, which not only fails to return oil but also causes liquid hammer to the compressor, damaging the compressor.

[0058] For example, in the following working conditions, it will have an adverse impact on the reliability of the air-conditioning system:

[0059] ① During the start-up stage under low-temperature working conditions. When the external environmental temperature is very low, such as when starting heating at -10°C, the initial exhaust temperature of the compressor is very low due to the low external temperature, usually lower than the external environmental temperature. At the moment of start-up, the saturated condensation temperature is usually close to the outer ring temperature, and at this time, the exhaust superheat < 0; as the start-up operation proceeds, both the exhaust temperature and the condensation temperature begin to rise, but the exhaust temperature rises slower than the condensation temperature, that is, there is a period when the exhaust superheat is < 0, and at this time, the liquid refrigerant returns through the oil return capillary.

[0060] ② When the load suddenly becomes small. The multi-connected air-conditioning system is characterized by one multi-connected unit + multiple indoor units. There is such a situation: all indoor units operate at full load during the day, and after work, most indoor units are turned off, leaving only one or two indoor units running (such as the security room). In this case, the load suddenly becomes small, the compressor runs at a reduced frequency according to the load, and the expansion valve opening is controlled according to the superheat. Due to the hysteresis of temperature, the valve opening also lags, and the refrigerant circulation volume in the system remains the original amount. At this time, a large amount of refrigerant circulates, resulting in a decrease in the compressor exhaust temperature and the exhaust superheat < 0. At this time, the liquid refrigerant returns through the oil return capillary.

[0061] Therefore, the traditional oil return capillary line has no control and is a pure mechanical structure, unable to identify the situation where the oil separator efficiency is low and liquid refrigerant enters the compressor to cause liquid hammer when the exhaust superheat is low.

[0062] For this reason, referring to Figure 2 As shown in the figure, the present invention provides a liquid return control method for the above air-conditioning system, mainly including the following steps:

[0063] S201. Obtain the exhaust superheat of the compressor.

[0064] Specifically, the superheat degree of the exhaust gas can be monitored and the superheat degree data of the exhaust gas can be obtained by a sensor installed on the exhaust side of the compressor.

[0065] S202. Determine that the superheat degree of the exhaust gas of the compressor meets the first preset condition, and control the solenoid valve to execute the anti-liquid-hammer strategy.

[0066] Specifically, set one or more conditions for judging whether the superheat degree of the exhaust gas is in the dangerous range. For example, when the superheat degree of the exhaust gas is lower than a certain threshold value, it indicates that there may be liquid refrigerant.

[0067] When the detected superheat degree of the exhaust gas meets the first preset condition, it indicates that there is a risk of liquid hammer caused by liquid return. At this time, control the solenoid valve to execute the anti-liquid-hammer strategy, cut off the passage of the oil return capillary, and prevent the liquid refrigerant from entering the compressor through the oil return capillary, so as to prevent the occurrence of liquid hammer phenomenon and protect the compressor from damage.

[0068] The present invention improves the traditional uncontrolled oil return capillary design by introducing a solenoid valve and intelligent control, realizes the active management of the liquid refrigerant entering the compressor; adjusts the state of the solenoid valve in real time according to the superheat degree of the exhaust gas of the compressor, can respond to the change of the system working condition in time, and improves the safety and stability of the system. By preventing the liquid hammer phenomenon, the service life of the compressor is prolonged, the maintenance cost is reduced, and the overall performance and reliability of the air-conditioning system are improved.

[0069] Therefore, the liquid return control method of the air-conditioning system provided by the embodiment of the present invention effectively prevents the liquid refrigerant flowing back from the oil separator from entering the compressor by monitoring the superheat degree of the exhaust gas of the compressor and controlling the solenoid valve according to the preset conditions, thereby preventing the liquid hammer phenomenon and achieving the purpose of protecting the compressor.

[0070] According to an embodiment of the present invention, the step of determining that the superheat degree of the exhaust gas of the compressor meets the first preset condition and controlling the solenoid valve to execute the anti-liquid-hammer strategy includes:

[0071] Determine that the superheat degree of the exhaust gas of the compressor is less than or equal to the first preset value, and control the solenoid valve to close.

[0072] Specifically, continuously obtain the superheat degree data of the exhaust gas through a sensor installed on the exhaust side of the compressor, and set a first preset value according to the working characteristics of the air-conditioning system, the properties of the refrigerant, and the threshold value of the liquid hammer risk. This preset value represents the lowest safety limit of the superheat degree of the exhaust gas. When it is lower than this value, there may be liquid refrigerant.

[0073] Compare the real-time monitored superheat degree of the exhaust gas with the set first preset value to determine whether the superheat degree of the exhaust gas is less than or equal to the first preset value. When the judgment result is that the superheat degree of the exhaust gas is less than or equal to the first preset value, it indicates that there may be a risk of liquid slugging in the system. At this time, execute the anti-liquid slugging strategy. To prevent the liquid refrigerant from entering the compressor through the oil return capillary and causing liquid slugging, control the solenoid valve to close and cut off the passage of the oil return capillary. This can prevent the flow of the liquid refrigerant and protect the compressor from damage.

[0074] The liquid return control method of the air-conditioning system provided by the embodiment of the present invention can accurately identify the risk that the low superheat degree of the compressor exhaust gas may cause liquid slugging, and take timely measures to prevent the liquid refrigerant from entering the compressor. This intelligent control method improves the safety, stability and reliability of the air-conditioning system, effectively extends the service life of the compressor, and reduces the maintenance cost.

[0075] According to an embodiment of the present invention, refer to Figure 3 As shown, the liquid return control method of the air-conditioning system of the present invention includes the following steps:

[0076] S301. Obtain the superheat degree of the exhaust gas of the compressor.

[0077] Specifically, the superheat degree data can be monitored and obtained through a sensor installed on the exhaust side of the compressor.

[0078] S302. Determine that the superheat degree of the exhaust gas of the compressor meets the second preset condition, and control the solenoid valve to execute the oil return strategy.

[0079] Specifically, according to the working characteristics of the air-conditioning system, the properties of the refrigerant, and the oil return requirements of the oil separator, set one or more second preset conditions. These conditions represent the range of superheat degree suitable for oil return, which can not only ensure the full evaporation of the refrigerant, but also ensure the effective return of the lubricating oil to the compressor.

[0080] Compare the real-time monitored superheat degree of the exhaust gas with the set second preset condition to determine whether the superheat degree of the exhaust gas meets the second preset condition. When the judgment result is that the superheat degree of the exhaust gas meets the second preset condition, it indicates that the system is in a suitable oil return state, and execute the oil return strategy.

[0081] When the superheat degree of the exhaust gas of the compressor detected by the liquid return control method of the air-conditioning system provided by the embodiment of the present invention meets the second preset condition, it indicates that there is no risk of liquid slugging, and the superheat degree of the exhaust gas reaches the suitable range for oil return. At this time, control the solenoid valve to execute the oil return strategy, which can not only ensure the full evaporation of the refrigerant, but also ensure the effective return of the lubricating oil to the compressor, so that the system runs reliably.

[0082] According to an embodiment of the present invention, the steps of determining that the exhaust superheat of the compressor satisfies the second preset condition and controlling the solenoid valve to execute the oil return strategy include:

[0083] Determine that the duration for which the exhaust superheat of the compressor is greater than the first preset value reaches the set duration, and control the solenoid valve to open.

[0084] Specifically, continuously obtain the exhaust superheat data through a sensor installed on the exhaust side of the compressor; set a first preset value according to the working characteristics of the air-conditioning system, the properties of the refrigerant, and the risk of preventing liquid slugging. At the same time, set an appropriate duration, which represents the time length for which the exhaust superheat needs to continuously be higher than the first preset value to ensure sufficient evaporation of the refrigerant and reduce the risk of liquid slugging.

[0085] Continuously monitor the exhaust superheat and record the time when the exhaust superheat is greater than the first preset value. When this time length reaches the set duration, it indicates that the system is in a relatively safe oil return state. When the judgment result is that the duration for which the exhaust superheat is greater than the first preset value reaches the set duration, it indicates that the system can start to execute the oil return operation.

[0086] To allow the lubricating oil separated by the oil separator to return to the compressor through the oil return capillary, control the solenoid valve to open and restore the passage of the oil return capillary. This can ensure the normal circulation of the lubricating oil and maintain the lubrication and cooling effects of the compressor.

[0087] The liquid return control method of the air-conditioning system provided by the embodiment of the present invention can, on the premise of ensuring safety, timely execute the oil return strategy, avoid the risk of liquid slugging caused by too low exhaust superheat, and at the same time ensure that the lubricating oil can effectively return to the compressor. This intelligent control method takes into account the needs of preventing liquid slugging and ensuring lubrication, improving the overall performance and reliability of the air-conditioning system. By setting the first preset value and the set duration, the oil return timing can be controlled more precisely, optimizing the operating efficiency of the system.

[0088] According to an embodiment of the present invention, the steps of determining that the exhaust superheat of the compressor satisfies the second preset condition and controlling the solenoid valve to execute the oil return strategy include:

[0089] Determine that the exhaust superheat of the compressor is greater than or equal to the second preset value, and control the solenoid valve to open; wherein, the second preset value is greater than the first preset value.

[0090] Specifically, the superheat data of the exhaust gas is continuously obtained through a sensor installed on the exhaust side of the compressor; according to the operating characteristics of the air-conditioning system, the properties of the refrigerant, and the requirements for preventing liquid slugging and ensuring lubrication, two preset values are set. Among them, the first preset value represents the lowest safety limit of the exhaust gas superheat. When it is lower than this value, there may be liquid refrigerant and it may cause the risk of liquid slugging. The second preset value is greater than the first preset value and represents the range of exhaust gas superheat that is more suitable for performing the oil return operation.

[0091] Compare the real-time monitored exhaust gas superheat with the set second preset value to determine whether the exhaust gas superheat is greater than or equal to the second preset value. When the judgment result is that the exhaust gas superheat is greater than or equal to the second preset value, it indicates that the system is in a suitable and relatively safe oil return state. In order to allow the lubricating oil separated by the oil separator to return to the compressor through the oil return capillary, control the solenoid valve to open and restore the passage of the oil return capillary. This can ensure the normal circulation of the lubricating oil and maintain the lubrication and cooling effects of the compressor.

[0092] The liquid return control method of the air-conditioning system provided by the embodiment of the present invention can execute the oil return strategy in a timely manner on the premise of ensuring safety, avoid the risk of liquid slugging caused by too low exhaust gas superheat, and at the same time ensure that the lubricating oil can effectively return to the compressor. Setting two preset values (the first preset value and the second preset value) can more precisely control the oil return timing, prevent liquid slugging, ensure the lubrication requirements, optimize the operating efficiency of the air-conditioning system and the service life of the equipment. This intelligent control method improves the overall performance and reliability of the air-conditioning system.

[0093] According to an embodiment of the present invention, the first preset value and the second preset value satisfy the following relationship:

[0094] A2 = A1 + Δ;

[0095] Wherein, A2 is the second preset value, A1 is the first preset value, and Δ is the preset safety margin.

[0096] This relationship means that the second preset value A2 is the sum of the first preset value A1 and the preset safety margin Δ. The setting of the preset safety margin Δ is to provide additional safety protection when implementing the oil return strategy, ensure that the exhaust gas superheat is high enough, reduce the risk of liquid slugging, and prevent frequent opening and closing actions of the liquid return.

[0097] Through this setting, when the exhaust gas superheat is less than or equal to the first preset value A1, the system will execute the anti-liquid slugging strategy, close the solenoid valve to prevent liquid refrigerant from entering the compressor and prevent liquid slugging. When the exhaust gas superheat further rises and reaches the second preset value (A2, that is, A1 + Δ), the system judges it as a suitable and relatively safe oil return state. At this time, control the solenoid valve to open and allow the lubricating oil to return to the compressor through the oil return capillary.

[0098] Under normal circumstances, the value of A1 = 0. When the value of A1 ≤ 0, it is liquid refrigerant, and the risk of compressor liquid return is very high; Δ is a preset safety margin to prevent frequent opening and closing actions of liquid return, generally 5 - 10 °C.

[0099] The liquid return control method of the air conditioning system provided by the embodiment of the present invention is set based on the relationship of the preset safety margin, so that the oil return control method can more accurately control the oil return timing on the premise of ensuring safety, prevent frequent opening and closing actions of liquid return, take into account the needs of preventing liquid hammer and ensuring lubrication, thereby improving the overall performance and reliability of the air conditioning system.

[0100] According to an embodiment of the present invention, the step of obtaining the exhaust superheat degree of the compressor includes:

[0101] Obtain the exhaust temperature of the compressor;

[0102] Obtain the condensation pressure of the compressor;

[0103] Determine the condensation temperature according to the condensation pressure;

[0104] Determine the exhaust superheat degree of the compressor according to the exhaust temperature and the condensation temperature.

[0105] Specifically, the exhaust temperature Td of the compressor can be detected by the exhaust temperature sensor 105 on the exhaust side of the compressor 102, the exhaust pressure, that is, the condensation pressure Pd, can be detected by the exhaust pressure sensor 106 on the exhaust side of the compressor 102, and the condensation temperature Ct can be automatically calculated according to the condensation pressure Pd. Then the exhaust superheat degree TdH = Td - Ct.

[0106] The following further describes the liquid return control method of the air conditioning system provided by the present invention in combination with a specific example. Refer to Figure 4 As shown, it mainly includes the following steps:

[0107] (1) Detect the exhaust superheat degree TdSH of the compressor;

[0108] (2) Compare the detected exhaust superheat degree TdSH of the compressor with the first preset value A1, and judge whether TdSH is less than or equal to A1;

[0109] (3) If TdSH ≤ A1, close the solenoid valve, cut off the passage of the oil return capillary, and prevent the liquid refrigerant from entering the compressor through the oil return capillary to cause liquid hammer;

[0110] (4) If TdSH > A1, continue to judge whether TdSH is greater than or equal to the second preset value A2, that is, A1 + Δ;

[0111] (5) If TdSH ≥ A2, the solenoid valve is opened to open the passage of the oil return capillary tube, and the oil separated by the oil separator can return to the compressor normally, enabling the system to operate reliably.

[0112] (6) Otherwise, the solenoid valve remains closed.

[0113] The liquid return control method of the air conditioning system provided by the embodiment of the present invention adds a solenoid valve on the oil return capillary tube and controls it according to the exhaust superheat degree. When the exhaust superheat degree is too small, the solenoid valve is closed to prevent the liquid refrigerant from entering the compressor and avoid liquid slugging. When the exhaust superheat degree rises to an appropriate value, the solenoid valve is opened, and at this time, the oil returned by the oil separator can smoothly enter the compressor, ensuring the stable and reliable operation of the system.

[0114] In the actual application process, when the load of the air conditioning system changes suddenly, it will cause a sharp drop in the exhaust temperature, which will also increase the risk of refrigerant liquid return and liquid slugging.

[0115] To address this situation, the liquid return control method of the air conditioning system of the present invention further introduces a control strategy for exhaust steep drop.

[0116] According to an embodiment of the present invention, the control strategy for exhaust steep drop in the liquid return control method of the air conditioning system provided by the present invention mainly includes: within a short period of time, when the descending rate of the exhaust temperature exceeds a preset limit value, it is considered that the exhaust steep drop occurs. At this time, the solenoid valve should also be closed until the exhaust temperature tends to be stable or rises, and then the solenoid valve is opened.

[0117] Specifically, it includes:

[0118] (1) Real-time monitor the exhaust temperature: Continuously obtain the exhaust temperature data through the exhaust temperature sensor 105 installed on the exhaust side of the compressor.

[0119] (2) Set the limit value: According to the working characteristics of the air conditioning system, the properties of the refrigerant, and the liquid slugging risk that may be caused by the steep drop of the exhaust temperature, set one or more limit values. These limit values are used to determine whether the change rate of the exhaust temperature exceeds the safe range.

[0120] (3) Judge whether the exhaust temperature shows a steep drop: Obtain the values of the exhaust temperature Td twice every n seconds. The first time is Td1, and the second time is Td2 (that is, Td2 is the value after n seconds). Then calculate the value of (Td1 - Td2) / n, which is the descending rate of the exhaust temperature.

[0121] (4) Execute the control strategy for exhaust steep drop: When (Td1 - Td2) / n ≥ C, it indicates that the descending rate of the exhaust temperature exceeds the first preset limit value C within a short period of time, and the system judges that it enters the exhaust steep drop state. At this time, to prevent the liquid slugging risk, control the solenoid valve to close and cut off the passage of the oil return capillary tube.

[0122] (5) Monitor the recovery of the exhaust gas temperature: Continuously monitor the change of the exhaust gas temperature. When the condition (Td2 - Td1) / m ≥ D is satisfied, it indicates that the rising rate of the exhaust gas temperature exceeds the second preset limit value D within m seconds, that is, the exhaust gas temperature rises or remains stable within m seconds, and the system determines that it has exited the exhaust gas steep drop state.

[0123] (6) Control the solenoid valve to resume opening: When the exhaust gas temperature recovers to the safe range, that is, when (Td2 - Td1) / m ≥ D is satisfied, control the solenoid valve to open, restore the passage of the oil return capillary, and allow the lubricating oil to return to the compressor through the oil return capillary to ensure the normal operation of the system and the lubrication requirements of the equipment.

[0124] For example, when n is taken as 10s, a C value ≥ 0.5 means that the exhaust gas temperature drops by at least 5°C within 10s, that is, it represents a steep drop in the exhaust gas. At this time, control the solenoid valve to close to prevent the risk of liquid slugging; when m is taken as 10s and the D value ≥ 0, it means that the exhaust gas temperature rises or remains stable within 10s, then exit this control and the solenoid valve resumes opening to ensure the stable and reliable operation of the system.

[0125] The liquid return control method of the air conditioning system provided by the embodiment of the present invention further enhances the protection ability of the system by introducing the control strategy of exhaust gas steep drop, can more comprehensively cope with the liquid slugging risk under various working conditions, and improves the safety and stability of the system. This intelligent control method can quickly respond under special conditions such as sudden load changes, effectively protect the compressor from damage, extend the service life of the equipment, and ensure the efficient and reliable operation of the air conditioning system.

[0126] The following describes the liquid return control device of the air conditioning system provided by the present invention. The liquid return control device of the air conditioning system described below can be mutually corresponding and referred to the liquid return control method of the air conditioning system described above.

[0127] According to an embodiment of the present invention, the present invention also provides a liquid return control device for the above air conditioning system, as Figure 1 shown, the air conditioning system includes: an oil return capillary 103 and a solenoid valve 104 connected between the oil return port of the oil separator 101 and the suction port of the compressor 102; as Figure 5 shown, the liquid return control device mainly includes: an acquisition module 501 and a control module 502. Among them, the acquisition module 501 is used to acquire the exhaust superheat degree of the compressor 102; the control module 502 is used to determine that the exhaust superheat degree of the compressor 102 satisfies the first preset condition and control the solenoid valve 104 to execute the anti-liquid slugging strategy.

[0128] The liquid return control device of the air conditioning system provided by the embodiment of the present invention monitors the exhaust superheat degree of the compressor and controls the solenoid valve according to preset conditions, effectively preventing the liquid refrigerant flowing back from the oil separator from entering the compressor, thereby preventing the liquid hammer phenomenon and achieving the purpose of protecting the compressor.

[0129] The present invention also provides an air conditioning system, as Figure 6 shown. The air conditioning system may include: a processor 601, a communications interface 602, a memory 603, and a communication bus 604. Among them, the processor 601, the communications interface 602, and the memory 603 complete mutual communication through the communication bus 604. The processor 601 can call the logical instructions in the memory 603 to execute the liquid return control method of the air conditioning system. The air conditioning system includes: an oil return capillary tube connected between the oil return port of the oil separator and the suction port of the compressor, and a solenoid valve. The liquid return control method includes: obtaining the exhaust superheat degree of the compressor; determining that the exhaust superheat degree of the compressor meets the first preset condition, and controlling the solenoid valve to execute the anti-liquid hammer strategy.

[0130] In addition, when the logical instructions in the above-mentioned memory 603 are implemented in the form of a software functional unit and sold or used as an independent product, they can be stored in a computer-readable storage medium. Based on such an understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or a part of this technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in various embodiments of the present invention. The foregoing storage medium includes: USB flash drives, mobile hard disks, read-only memories (ROM, Read-Only Memory), random access memories (RAM, Random Access Memory), magnetic disks, or optical discs, etc., which can store program codes.

[0131] On the other hand, the present invention also provides a computer program product. The computer program product includes a computer program. The computer program can be stored on a non-transitory computer-readable storage medium. When the computer program is executed by a processor, the computer can execute the liquid return control method of the air conditioning system provided by the above-mentioned methods. The air conditioning system includes: an oil return capillary tube connected between the oil return port of the oil separator and the suction port of the compressor, and a solenoid valve. The liquid return control method includes: obtaining the exhaust superheat degree of the compressor; determining that the exhaust superheat degree of the compressor meets the first preset condition, and controlling the solenoid valve to execute the anti-liquid hammer strategy.

[0132] In another aspect, the present invention also provides a non-transitory computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, it implements the liquid return control method of the air-conditioning system provided by the above-mentioned various methods. The air-conditioning system includes: a liquid return capillary tube and an electromagnetic valve connected between the oil return port of the oil separator and the suction port of the compressor; the liquid return control method includes: obtaining the exhaust superheat degree of the compressor; determining that the exhaust superheat degree of the compressor meets a first preset condition, and controlling the electromagnetic valve to execute an anti-liquid hammer strategy.

[0133] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed to multiple network units. Some or all of the modules can be selected according to actual needs to achieve the purpose of the solution of this embodiment. Those of ordinary skill in the art can understand and implement it without creative work.

[0134] Through the description of the above embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus a necessary general hardware platform, and of course, it can also be implemented by hardware. Based on such an understanding, the above technical solution, in essence, or the part that contributes to the prior art can be embodied in the form of a software product. The computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to enable a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment or some parts of the embodiments.

[0135] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or equivalently replace some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of each embodiment of the present invention.

Claims

1. A method for controlling liquid return of an air conditioning system, characterized in that, The air-conditioning system includes: an oil return capillary tube and a solenoid valve connected between the oil return port of the oil separator and the suction port of the compressor; the liquid return control method includes: Obtain the superheat degree of the compressor exhaust. Determine that the superheat degree of the compressor exhaust meets the first preset condition, and control the solenoid valve to execute the anti-liquid hammer strategy.

2. The liquid return control method of the air conditioning system according to claim 1, wherein, The step of determining that the superheat degree of the compressor exhaust meets the first preset condition and controlling the solenoid valve to execute the anti-liquid hammer strategy includes: Determine that the superheat degree of the compressor exhaust is less than or equal to the first preset value, and control the solenoid valve to close.

3. The liquid return control method of the air conditioning system according to claim 2, characterized in that It further includes: Determine that the superheat degree of the compressor exhaust meets the second preset condition, and control the solenoid valve to execute the oil return strategy.

4. The liquid return control method of the air conditioning system according to claim 3, characterized in that, The step of determining that the superheat degree of the compressor exhaust meets the second preset condition and controlling the solenoid valve to execute the oil return strategy includes: Determine that the duration for which the superheat degree of the compressor exhaust is greater than the first preset value reaches the set duration, and control the solenoid valve to open.

5. The liquid return control method of the air conditioning system according to claim 3, characterized in that, The step of determining that the superheat degree of the compressor exhaust meets the second preset condition and controlling the solenoid valve to execute the oil return strategy includes: Determine that the superheat degree of the compressor exhaust is greater than or equal to the second preset value, and control the solenoid valve to open; wherein, the second preset value is greater than the first preset value.

6. The liquid return control method of the air conditioning system according to claim 5, characterized in that, The first preset value and the second preset value satisfy the following relationship: A2 = A1 + Δ; where, A2 is the second preset value, A1 is the first preset value, and Δ is the preset safety margin.

7. The liquid return control method of the air conditioning system according to any one of claims 1-6, characterized in that, The step of obtaining the superheat degree of the compressor exhaust includes: Obtain the exhaust temperature of the compressor; Obtain the condensation pressure of the compressor; Determine the condensation temperature according to the condensation pressure; Determine the superheat degree of the compressor exhaust according to the exhaust temperature and the condensation temperature.

8. The liquid return control method of the air conditioning system according to claim 7, characterized in that, The step of determining the superheat degree of the compressor exhaust according to the exhaust temperature and the condensation temperature includes: TdSh = Td - Ct; where, TdSH is the superheat degree of the compressor exhaust, Td is the exhaust temperature, and Ct is the condensation temperature.

9. A liquid return control device for an air conditioning system, characterized in that, The air-conditioning system includes: an oil return capillary tube and a solenoid valve connected between the oil return port of the oil separator and the suction port of the compressor; the liquid return control device includes: An acquisition module for obtaining the superheat degree of the compressor exhaust; A control module for determining that the superheat degree of the compressor exhaust meets the first preset condition and controlling the solenoid valve to execute the anti-liquid hammer strategy.

10. An air conditioning system, comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, characterized in that, When the processor executes the program, it implements the liquid return control method of the air-conditioning system as described in any one of claims 1-8.

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