Refrigeration anti-freezing control method and device of air conditioning system and medium

Abstract

The application provides a refrigeration anti-freezing control method, device and medium of an air conditioning system, which comprises the following steps: a presetting step: presetting a return air parameter compensation amount according to an outdoor environment temperature; a detecting step: detecting a real-time return air parameter of a low-pressure side of the air conditioning system in a refrigeration mode; a comparing step: calculating a corrected return air parameter according to the sum of the real-time return air parameter and the corresponding return air parameter compensation amount, and comparing whether the corrected return air parameter is less than a first return air parameter threshold; and a controlling step: if the corrected return air parameter is less than the first return air parameter threshold, controlling the air conditioning system to enter an anti-freezing protection mode. The application improves the accuracy of anti-freezing judgment and is not disturbed by conditions such as flow deviation; and the compressor can be controlled to start and stop to realize anti-freezing protection without communication between an indoor unit and an outdoor unit.

Description

Technical Field

[0001] This invention relates to the field of air conditioning, specifically to a method, device, and medium for controlling the refrigeration and antifreeze of an air conditioning system. Background Technology

[0002] Air conditioner evaporators can experience poor refrigerant evaporation due to low ambient temperature, indoor unit motor malfunction, or prolonged use leading to dirt and blockage. This can cause the evaporator to freeze over time or allow liquid refrigerant to enter the compressor, causing liquid slugging. In such cases, it is necessary to implement antifreeze protection for the evaporator promptly.

[0003] Existing anti-freeze control logic typically relies on evaporator temperature for freeze protection. However, uneven refrigerant distribution can occur in the evaporator, reducing the amount of refrigerant flowing through the evaporator coil. This means the detected evaporator coil temperature may not reflect the actual lowest evaporator temperature, potentially leading to inaccurate freeze detection. Consequently, when the indoor unit freezes, anti-freeze protection may fail to activate in time, potentially damaging the evaporator structure. Furthermore, air conditioner operation is controlled by the indoor unit's mainboard, requiring communication between the indoor and outdoor units to control the outdoor compressor's start and stop. Air conditioners where the indoor and outdoor units do not communicate cannot achieve anti-freeze control. Summary of the Invention

[0004] To address the above problems, this invention provides a cooling anti-freeze control method, device, and medium for an air conditioning system. By pre-setting a return gas parameter compensation amount based on the outdoor ambient temperature and compensating the real-time return gas parameters on the low-pressure side of the outdoor unit, the operating status of the indoor evaporator can be reflected without communication between the indoor and outdoor units, and it can determine whether to enter the anti-freeze protection mode. This improves the accuracy of evaporator anti-freeze control and helps ensure the stable operation of the air conditioning system.

[0005] This invention provides a method for controlling the cooling and anti-freezing of an air conditioning system, comprising the following steps:

[0006] Preset steps: Based on the outdoor ambient temperature, preset the return air parameter compensation amount;

[0007] Testing steps: In cooling mode, test the real-time return gas parameters on the low-pressure side of the air conditioning system;

[0008] Comparison steps: Calculate the corrected return gas parameter based on the sum of the real-time return gas parameter and the corresponding return gas parameter compensation amount, and compare whether the corrected return gas parameter is less than the first return gas parameter threshold.

[0009] Control steps: If the corrected return gas parameter is less than the first return gas parameter threshold, control the air conditioning system to enter the anti-freeze protection mode.

[0010] By pre-setting a compensation amount for the return gas parameter based on the outdoor ambient temperature, and obtaining a corrected return gas parameter based on the real-time return gas parameter on the low-pressure side and the compensation amount, the system determines whether to enter the anti-freeze protection mode by comparing the corrected return gas parameter with the first return gas parameter threshold. When the corrected return gas parameter is lower than the first return gas parameter threshold, the evaporator temperature is low and there is a possibility of freezing. In this case, the anti-freeze protection mode is activated to prevent the evaporator from freezing in a timely manner. Furthermore, collecting the return gas parameter on the low-pressure side of the refrigeration system can more accurately identify the freezing state of the evaporator and is not affected by factors such as flow deviation. Since the low-pressure side of the refrigeration system is located outdoors, the compressor start and stop can be controlled to achieve anti-freeze protection without communication between the indoor and outdoor units, thus saving on air conditioning system costs.

[0011] In the optional technical solution of the present invention, in the preset steps, if the outdoor ambient temperature is greater than the first preset temperature, it corresponds to the first return air parameter compensation amount; if the outdoor ambient temperature is greater than the second preset temperature but not greater than the first preset temperature, it corresponds to the second return air parameter compensation amount; if the outdoor ambient temperature is not greater than the second preset temperature, it corresponds to the third return air parameter compensation amount. If the first preset temperature is greater than the second preset temperature, the first return air parameter compensation amount, the second return air parameter compensation amount, and the third return air parameter compensation amount increase sequentially.

[0012] According to this technical solution, the higher the outdoor ambient temperature, the greater the difference between the evaporator temperature and the saturation temperature corresponding to the actual collected pressure, or the actual collected return gas temperature, due to the cooling loss in the pipeline. Therefore, the corresponding compensation amount is also greater. By designing the return gas parameter compensation amount, the saturation temperature corresponding to the corrected return gas parameter can be made closer to the evaporator temperature, thereby improving the accuracy of anti-freeze judgment, enabling the air conditioner to promptly enter anti-freeze protection, and ensuring the operational reliability of the air conditioning system.

[0013] In an optional technical solution of the present invention, the air conditioning system includes at least a compressor, an outdoor heat exchanger, a throttling element, an indoor heat exchanger, and an outdoor fan connected in sequence to form a refrigerant circulation path.

[0014] In the optional technical solution of the present invention, in the control step, the anti-freeze protection mode is executed: the outdoor fan corresponding to the compressor and the outdoor heat exchanger is stopped, while the indoor heat exchanger operates normally.

[0015] In the anti-freeze protection mode described above, the outdoor fan stops running, which reduces the heat released from the outdoor heat exchanger. This allows the refrigerant at the outlet of the condenser (outdoor heat exchanger) to enter the evaporator (indoor heat exchanger) at a relatively high temperature, thereby raising the evaporator temperature and alleviating the evaporator icing situation. The evaporator operates normally, maintaining indoor cooling. Furthermore, the evaporator absorbs indoor heat, which further helps alleviate the evaporator icing situation, increases the evaporator heating rate, and accelerates the melting of ice on the evaporator surface.

[0016] In the optional technical solution of the present invention, an anti-freeze protection mode exit step is also included:

[0017] Compare whether the corrected return gas parameter is greater than the second return gas parameter threshold. If the second return gas parameter threshold is greater than the first return gas parameter threshold;

[0018] If the corrected return gas parameter is greater than the second return gas parameter threshold, then the compressor and outdoor fan will be started.

[0019] According to this technical solution, when the corrected return gas parameter is greater than the second return gas parameter threshold, the evaporator temperature is unlikely to freeze. Therefore, the anti-freeze protection mode can be exited to ensure the normal operation of the refrigeration system and improve the user experience.

[0020] In the optional technical solution of the present invention, an anti-freeze protection mode exit step is also included: after the compressor stops running, the downtime of the compressor is detected, and after the downtime exceeds the specified time, the compressor is forced to start and the outdoor fan is started.

[0021] According to this technical solution, under low-temperature conditions, the refrigerant itself has low pressure / temperature, and pressure / temperature cannot be used as the sole condition for exiting antifreeze. By detecting the compressor's downtime, the compressor and outdoor fan are restarted after the downtime exceeds the specified time to ensure the normal operation of the air conditioning system and meet the cooling demand.

[0022] In the optional technical solution of the present invention, the air conditioning system is a fixed frequency air conditioning system, and the air conditioning system further includes a temperature sensing bulb for detecting the return air temperature between the indoor heat exchanger and the return air end of the compressor. The first return air parameter threshold is a first return air temperature threshold, the second return air parameter threshold is a second return air temperature threshold, the first return air temperature threshold is -5℃ to 5℃, and the second return air temperature threshold is 6℃ to 15℃.

[0023] Compared to directly detecting the evaporator temperature, detecting the return gas temperature more accurately identifies the evaporator's evaporation effect and is unaffected by evaporator flow deviation, resulting in higher accuracy. Furthermore, since the thermal expansion valve, temperature sensor, and compressor are all located outdoors, communication between the indoor and outdoor units is unnecessary, saving on communication line costs. For fixed-frequency air conditioning systems, using a temperature sensor to obtain the return gas temperature reduces manufacturing costs. Selecting an appropriate first temperature threshold range allows the evaporator to promptly enter anti-freeze protection mode under low-temperature conditions, preventing evaporator icing and improving the anti-freeze performance of the air conditioning system. Selecting an appropriate second temperature threshold range allows the evaporator temperature to promptly exit anti-freeze protection mode after rising, ensuring normal operation of the air conditioning system and improving user experience.

[0024] In the optional technical solution of the present invention, the air conditioning system is a variable frequency air conditioning system, and the air conditioning system further includes a pressure sensor for detecting the return gas pressure between the indoor heat exchanger and the return gas end of the compressor. The first return gas parameter threshold is a first return gas pressure threshold, and the second return gas parameter threshold is a second return gas pressure threshold. The first return gas parameter threshold is 0.57MPa-0.83MPa, and the second return gas parameter threshold is 0.75MPa-1.15MPa.

[0025] According to this technical solution, compared to directly detecting the evaporator temperature, a pressure sensor located on the pipeline between the indoor heat exchanger and the compressor return gas end can more accurately identify the evaporation effect of the evaporator and is not affected by evaporator flow deviation, resulting in higher accuracy. Furthermore, since both the pressure sensor and the compressor are located outdoors, there is no need for communication between the indoor and outdoor units, saving on the cost of communication lines. For inverter air conditioning systems, the pressure sensor is an integral component of the system, thus incurring no additional cost. Selecting an appropriate first pressure threshold range allows the evaporator to promptly enter anti-freeze protection mode under low-temperature conditions, preventing evaporator icing and improving the anti-freeze performance of the air conditioning system. Selecting an appropriate second pressure threshold range allows the evaporator temperature to promptly exit anti-freeze protection mode after rising, ensuring the normal operation of the air conditioning system and improving the user experience.

[0026] The present invention further provides a refrigeration anti-freeze control device for an air conditioning system, comprising:

[0027] The preset module presets the return air parameter compensation amount based on the outdoor ambient temperature.

[0028] The detection module detects the real-time return gas parameters on the low-pressure side of the air conditioning system in cooling mode.

[0029] The comparison module calculates the corrected return gas parameter based on the sum of the real-time return gas parameter and the corresponding return gas parameter compensation amount, and compares whether the corrected return gas parameter is less than the first return gas parameter threshold.

[0030] If the corrected return gas parameter is less than the first return gas parameter threshold, the control module will control the air conditioning system to enter the anti-freeze protection mode.

[0031] The present invention also provides a computer-readable storage medium storing a computer program, which, when executed, implements the cooling anti-freezing control method of the air conditioning system as described above. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the air conditioning system in the first embodiment of the present invention.

[0033] Figure 2 This is a schematic diagram of the cooling and anti-freezing control method of the air conditioning system in the first embodiment of the present invention.

[0034] Figure 3 This is a schematic diagram of the modular structure of the refrigeration antifreeze control device of the air conditioning system in the first embodiment of the present invention.

[0035] Figure label:

[0036] Compressor 11; Four-way valve 12; Outdoor heat exchanger 13; First throttling element 14; Liquid storage tank 15; Second throttling element 16; Thermal expansion valve 17; Indoor heat exchanger 18; Gas-liquid separator 19; Temperature sensor 20; One-way valve 2; Pressure sensor 3; Low-pressure switch 4; High-pressure switch 5; Preset module 61; Detection module 62; Comparison module 63; Control module 64. Detailed Implementation

[0037] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0038] [First Implementation Method]

[0039] like Figure 1As shown, the first embodiment of the present invention provides an air conditioning system, including a compressor 11, a four-way valve 12, an outdoor heat exchanger 13, a first throttling element 14, a liquid receiver 15, a second throttling element 16, a thermostatic expansion valve 17, an indoor heat exchanger 18, and a gas-liquid separator 19 connected in sequence to form a refrigerant circulation path; a one-way valve 2 is provided in parallel at both ends of the second throttling element, and the one-way valve 2 controls the unidirectional flow of refrigerant from the liquid receiver 15 to the indoor heat exchanger 18; a pressure sensor 3 is provided on the pipeline between the indoor heat exchanger 18 and the four-way valve 12; the air conditioning system also includes: a low-pressure switch 4, located between the four-way valve 12 and the gas-liquid separator 19; and a high-pressure switch 5, located between the compressor 11 and the four-way valve 12. In this system, compressor 11 is a variable frequency compressor; the liquid receiver 15 functions similarly to the gas-liquid separator 19, with the separated gas entering compressor 11 via branch pipes to replenish refrigerant, and the liquid refrigerant entering the main refrigerant line; a pressure switch monitors the refrigerant pressure in the air conditioning pipes and feeds it back to the air conditioning controller (not shown in the figure); the thermostatic expansion valve 17, in conjunction with the temperature sensor 20, collects the temperature at the outlet of the indoor heat exchanger 18. When the refrigerant pressure is too low, the low-pressure switch 4 opens, and the controller, upon receiving this signal, knows that there is insufficient refrigerant in the system and controls compressor 11 to stop working; when the refrigerant pressure is too high, the high-pressure switch 5 opens, and the controller, upon receiving this signal, controls compressor 11 to stop working to prevent excessive pressure from causing pipe bursting. Preferably, the air conditioning system in this first embodiment is a variable frequency air conditioning system.

[0040] Compared to directly detecting the evaporator temperature, the pressure sensor 3, located on the pipeline between the indoor heat exchanger 18 and the four-way valve 12, detects the pressure on the low-pressure side, which more accurately identifies the evaporation effect of the evaporator and is not affected by evaporator flow deviation, thus offering higher accuracy. Furthermore, since both the pressure sensor 3 and the compressor 11 are located outdoors, communication between the indoor and outdoor units is unnecessary, saving on the cost of communication lines between them. For inverter air conditioning systems, the pressure sensor 3 is an integral component of the system, therefore incurring no additional cost. It should be noted that although the first embodiment of this invention shows the above-described air conditioning system structure, it should not be construed as limiting the air conditioning system. Other air conditioning systems with different structures are also applicable to the refrigeration anti-freeze control method provided in the first embodiment of this invention.

[0041] like Figure 2 As shown, corresponding to the above-mentioned air conditioning system, the present invention provides a cooling anti-freezing control method for an air conditioning system, comprising the following steps:

[0042] Preset steps: Preset the pressure compensation amount based on the outdoor ambient temperature;

[0043] Detection steps: In cooling mode, use pressure sensor 3 to detect the real-time pressure on the low-pressure side of the air conditioning system;

[0044] Comparison steps: Calculate the corrected pressure based on the sum of the real-time pressure and the corresponding pressure compensation amount, and compare whether the corrected pressure is less than the first pressure threshold.

[0045] Control steps: If the corrected pressure is less than the first pressure threshold, control the air conditioning system to enter the anti-freeze protection mode.

[0046] By presetting a pressure compensation amount based on the outdoor ambient temperature and obtaining a corrected pressure based on the real-time pressure on the low-pressure side and the pressure compensation amount, the system determines whether to enter the anti-freeze protection mode by comparing the corrected pressure with a first pressure threshold. When the corrected pressure is lower than the first pressure threshold, the evaporator temperature is low and there is a possibility of freezing. In this case, the anti-freeze protection mode is activated to prevent the evaporator from freezing in a timely manner. Furthermore, by collecting the pressure on the low-pressure side of the refrigeration system, the freezing status of the evaporator can be more accurately identified, and it is not affected by factors such as flow deviation. Since the low-pressure side of the refrigeration system is located outdoors, the compressor 11 can be controlled to start and stop to achieve anti-freeze protection without the need for communication between the indoor and outdoor units, thus saving on air conditioning system costs.

[0047] In a preferred embodiment of the present invention, during the control step, the anti-freeze protection mode is executed: the outdoor fan corresponding to the compressor 11 and the outdoor heat exchanger 13 is stopped, while the indoor heat exchanger 18 operates normally. In the anti-freeze protection mode, the outdoor fan stops operating, reducing the heat release from the outdoor heat exchanger 13. This allows the refrigerant at the outlet of the condenser (outdoor heat exchanger 13) to enter the evaporator (indoor heat exchanger 18) at a relatively high temperature, thereby increasing the evaporator temperature and alleviating evaporator icing. The normal operation of the evaporator maintains indoor cooling, and the evaporator absorbs indoor heat, further alleviating evaporator icing, increasing the evaporator heating rate, and accelerating the melting of ice on the evaporator surface.

[0048] In a preferred embodiment of the present invention, the method further includes an anti-freeze protection mode exit step: comparing whether the correction pressure is greater than a second pressure threshold, wherein the second pressure threshold is greater than a first pressure threshold; if the correction pressure is greater than the second pressure threshold, then controlling the compressor 11 to start and the outdoor fan (not shown in the figure) to start.

[0049] Using the above method, when the corrected pressure exceeds the second pressure threshold (e.g., the second pressure threshold is 0.86 MPa, corresponding to a saturation temperature of 6°C), the evaporator temperature is unlikely to freeze. Therefore, the anti-freeze protection mode can be exited, ensuring the normal operation of the refrigeration system and improving the user experience. In some implementations, the anti-freeze protection mode exit steps include: after the compressor 11 stops running, detecting the stop time of the compressor 11, and if the stop time exceeds a specified duration, controlling the compressor 11 to forcibly start and the outdoor fan to start. Under low-temperature conditions, the refrigerant pressure itself is low, and pressure cannot be used as the sole condition for exiting the anti-freeze protection mode (this may prevent the anti-freeze protection mode from exiting, affecting the air conditioner's cooling effect). By detecting the stop time of the compressor 11, and restarting the compressor 11 and outdoor fan after the stop time exceeds a specified duration, the normal operation of the air conditioning system is ensured, meeting the cooling requirements.

[0050] In a preferred embodiment of the present invention, the first pressure threshold is 0.57-0.83 MPa, and the second pressure threshold is 0.75-1.15 MPa. Selecting a suitable first pressure threshold range allows the evaporator to promptly enter the anti-freeze protection mode under low-temperature conditions, preventing evaporator icing and improving the anti-freeze performance of the air conditioning system. Selecting a suitable second pressure threshold range allows the evaporator temperature to promptly exit the anti-freeze protection mode after rising, ensuring the normal operation of the air conditioning system and improving the user experience. It should be noted that although the embodiments of the present invention show the above-mentioned pressure threshold ranges, this should not constitute a limitation on the pressure range. Those skilled in the art can adjust the ranges of the first and second pressure thresholds according to actual conditions.

[0051] The higher the outdoor ambient temperature, the greater the difference between the evaporator temperature and the saturation temperature corresponding to the actual collected pressure due to cooling losses in the pipeline, and the greater the corresponding pressure compensation amount. By designing the pressure compensation amount, the saturation temperature corresponding to the corrected pressure can be made closer to the evaporator temperature, thereby improving the accuracy of anti-freeze judgment, enabling the air conditioner to enter anti-freeze protection in a timely manner, and ensuring the operational reliability of the air conditioning system. In a preferred embodiment of the present invention, the outdoor ambient temperature is greater than a first preset temperature, corresponding to a first pressure compensation amount; the outdoor ambient temperature is greater than a second preset temperature but not greater than the first preset temperature, corresponding to a second pressure compensation amount; the outdoor ambient temperature is not greater than the second preset temperature, corresponding to a third pressure compensation amount. The first, second, and third pressure compensation amounts increase sequentially from the first preset temperature to the second preset temperature. Specifically, for example, when the outdoor ambient temperature is greater than 35°C, the first pressure compensation amount is -0.06 MPa; when the outdoor ambient temperature is greater than 20°C but not greater than 35°C, the second pressure compensation amount is -0.03 MPa; and when the outdoor ambient temperature is not greater than 20°C, the third pressure compensation amount is 0 MPa. It should be noted that although the first embodiment of the present invention shows the specific values ​​of the pressure compensation amount, those skilled in the art can make adjustments according to the actual situation, and are not limited to the examples shown in this embodiment; furthermore, the pressure compensation amount can also be a numerical range, such as the range of the first pressure compensation amount being (-0.2 to 0 MPa), the range of the second pressure compensation amount being (-0.2 to 0 MPa), and the range of the third pressure compensation amount being (-0.2 to 0 MPa). The ranges of the first, second, and third pressure compensation amounts can be the same or different.

[0052] In this embodiment, through experimental testing, before approaching the anti-freeze protection, the pressure difference between the evaporator and the low-pressure side of the outdoor unit is less than 0.02 MPa (which is compatible with the pressure compensation amount). The liquid pressure loss is small. Based on the real-time pressure of the low-pressure side of the outdoor unit and the pressure compensation amount, the operating conditions of the indoor evaporator can be effectively reflected, and the anti-freeze control of the evaporator can be accurately realized.

[0053] It should be noted that the cooling anti-freezing control method of this embodiment is also applicable to fixed-frequency air conditioning systems, and has a wide range of applications.

[0054] like Figure 3 As shown, the first embodiment of the present invention further provides a refrigeration anti-freeze control device for an air conditioning system, comprising:

[0055] Preset module 61 presets the return air parameter compensation amount according to the outdoor ambient temperature;

[0056] The detection module 62 detects the real-time return gas parameters on the low-pressure side of the air conditioning system in cooling mode.

[0057] Comparison module 63 calculates the corrected return gas parameter based on the sum of the real-time return gas parameter and the corresponding return gas parameter compensation amount, and compares whether the corrected return gas parameter is less than the first return gas parameter threshold.

[0058] If the corrected return gas parameter is greater than the preset return gas parameter threshold, the control module 64 controls the air conditioning system to enter the anti-freeze protection mode.

[0059] Specifically, the aforementioned return gas parameter is the return gas pressure. The preset module 61, comparison module 63, and control module 64 are at least partially integrated into the controller of the air conditioning system. The controller can be an integrated circuit chip with signal processing capabilities. The aforementioned controller can be a general-purpose processor, including a central processing unit, or it can be a microcontroller, microcontroller unit, complex programmable logic device, field-programmable gate array, application-specific integrated circuit, embedded ARM, etc. The controller can implement or execute the methods, steps, and flowcharts disclosed in the embodiments of this invention.

[0060] In one feasible implementation, the air conditioning system may further include a memory (not shown) for storing program instructions executable by the controller, which, when executed, implement the aforementioned cooling anti-freeze protection control method. The memory may be a separate external memory, including but not limited to random access memory, read-only memory, programmable read-only memory, erasable read-only memory, and electrically erasable read-only memory. The memory may also be integrated with the controller; for example, the memory may be integrated with the controller within the same chip.

[0061] In embodiments of the present invention, a temperature detection module is also included for detecting the outdoor ambient temperature. The temperature detection module can be installed in the outdoor heat exchanger 13.

[0062] In this embodiment of the invention, the refrigeration anti-freeze control device of the air conditioning system presets a return gas parameter compensation amount based on the outdoor ambient temperature, and obtains a corrected return gas parameter based on the real-time return gas parameter detected on the low-pressure side and the return gas parameter compensation amount. It then determines whether to enter the anti-freeze protection mode by comparing the corrected return gas parameter with a first return gas parameter threshold, thus enabling timely anti-freeze protection of the evaporator. Furthermore, collecting the return gas parameters from the low-pressure side of the refrigeration system allows for more accurate identification of the evaporator's freezing state, unaffected by flow deviation or other factors. Since the low-pressure side of the refrigeration system is located outdoors, communication between the indoor and outdoor units is unnecessary to control the compressor 11's start and stop for anti-freeze protection, saving on air conditioning system costs.

[0063] [Second Implementation Method]

[0064] The second embodiment of the present invention provides an air conditioning system, which has a structure that is basically the same as that of the first embodiment. Preferably, in the second embodiment, the air conditioning system is a fixed-frequency air conditioner and does not include the pressure sensor 3, so as to reduce manufacturing costs.

[0065] The second embodiment of the present invention provides a cooling anti-freezing control method for an air conditioning system, comprising the following steps:

[0066] Preset steps: Based on the outdoor ambient temperature, preset the return air temperature compensation amount;

[0067] Testing steps: In cooling mode, test the real-time return air temperature on the low-pressure side of the air conditioning system;

[0068] Comparison steps: Calculate the corrected return gas temperature based on the sum of the real-time return gas temperature and the corresponding return gas temperature compensation amount, and compare whether the corrected return gas temperature is less than the first return gas temperature threshold.

[0069] Control steps: If the corrected return air temperature is less than the first return air temperature threshold, control the air conditioning system to enter the anti-freeze protection mode.

[0070] By preset a return gas temperature compensation amount based on the outdoor ambient temperature, and obtaining a corrected return gas temperature based on the real-time return gas temperature on the low-pressure side and the return gas temperature compensation amount, the system determines whether to enter the anti-freeze protection mode by comparing the corrected return gas temperature with a first return gas temperature threshold. When the corrected return gas temperature is lower than the first return gas temperature threshold, the evaporator temperature is low and there is a possibility of freezing. In this case, the anti-freeze protection mode is activated to prevent the evaporator from freezing in a timely manner. Furthermore, collecting the return gas temperature on the low-pressure side of the refrigeration system can more accurately identify the freezing state of the evaporator and is not affected by factors such as flow deviation. Since the low-pressure side of the refrigeration system is located outdoors, the compressor 11 can be controlled to start and stop to achieve anti-freeze protection without the need for communication between the indoor and outdoor units, thus saving on air conditioning system costs.

[0071] The higher the outdoor ambient temperature, the greater the difference between the evaporator temperature and the saturation temperature corresponding to the actual collected return gas temperature due to cooling losses in the pipeline, and the greater the corresponding return gas temperature compensation amount. By designing the return gas temperature compensation amount, the saturation temperature corresponding to the corrected return gas temperature can be made closer to the evaporator temperature, thereby improving the accuracy of anti-freeze judgment, enabling the air conditioner to enter anti-freeze protection in a timely manner, and ensuring the operational reliability of the air conditioning system. In a preferred embodiment of the present invention, in the preset steps, if the outdoor ambient temperature is greater than a first preset temperature, a first return gas temperature compensation amount is assigned; if the outdoor ambient temperature is greater than a second preset temperature but not greater than the first preset temperature, a second return gas temperature compensation amount is assigned; if the outdoor ambient temperature is not greater than the second preset temperature, a third return gas temperature compensation amount is assigned. The first preset temperature is greater than the second preset temperature, and the first, second, and third return gas temperature compensation amounts increase sequentially. Specifically, if the outdoor ambient temperature is greater than 35℃, the first return air temperature compensation is -1℃; if the outdoor ambient temperature is greater than 20℃ but not greater than 35℃, the second return air temperature compensation is -0.5℃; and if the outdoor ambient temperature is not greater than 20℃, the third return air temperature compensation is 0℃. It should be noted that although the first embodiment of the present invention shows the specific values ​​of the above-mentioned return air temperature compensation, those skilled in the art can adjust them according to actual conditions, and are not limited to the examples shown in this embodiment. Furthermore, the return air temperature compensation can also be a range of values, such as the range of the first return air temperature compensation being (-2 to 4℃), the range of the second return air temperature compensation being (-2 to 4℃), and the range of the third return air temperature compensation being (-2 to 4℃). The ranges of the first, second, and third return air temperature compensation can be the same or different.

[0072] In this embodiment of the invention, the anti-freeze control device of the air conditioning system presets a return gas temperature compensation amount based on the outdoor ambient temperature, and obtains a corrected return gas temperature based on the real-time return gas temperature detected on the low-pressure side and the return gas temperature compensation amount. It then determines whether to enter the anti-freeze protection mode by comparing the corrected return gas temperature with a first return gas temperature threshold, thus enabling timely anti-freeze protection of the evaporator. Furthermore, collecting the return gas temperature on the low-pressure side of the refrigeration system allows for more accurate identification of the evaporator's freezing state, unaffected by factors such as flow deviation. Since the low-pressure side of the refrigeration system is located outdoors, and the temperature sensor 20 is also located outdoors, communication between the indoor and outdoor units is unnecessary to control the compressor 11's start and stop for anti-freeze protection, saving on air conditioning system costs.

[0073] In a preferred embodiment of the present invention, during the control step, the anti-freeze protection mode is executed: the outdoor fan corresponding to the compressor 11 and the outdoor heat exchanger 13 is stopped, while the indoor heat exchanger 18 operates normally. In the anti-freeze protection mode, the outdoor fan stops operating, reducing the heat release from the outdoor heat exchanger 13. This allows the refrigerant at the outlet of the condenser (outdoor heat exchanger 13) to enter the evaporator (indoor heat exchanger 18) at a relatively high temperature, thereby increasing the evaporator temperature and alleviating evaporator icing. The normal operation of the evaporator maintains indoor cooling, and the evaporator absorbs indoor heat, further alleviating evaporator icing, increasing the evaporator heating rate, and accelerating the melting of ice on the evaporator surface.

[0074] In a preferred embodiment of the present invention, the method further includes an anti-freeze protection mode exit step: comparing whether the corrected return gas temperature is greater than a second return gas temperature threshold, wherein the second return gas temperature threshold is greater than a first return gas temperature threshold; if the corrected return gas temperature is greater than the second return gas temperature threshold, then the compressor 11 is controlled to start and the outdoor fan (not shown in the figure) is started.

[0075] By using the above method, when the corrected return gas temperature is greater than the second return gas temperature threshold, such as 8°C, the evaporator temperature is unlikely to freeze. Therefore, the anti-freeze protection mode can be exited to ensure the normal operation of the refrigeration system and improve the user experience.

[0076] In some implementations, the anti-freeze protection mode exit step includes: after the compressor 11 stops running, detecting the duration of compressor 11's shutdown, and if the shutdown duration exceeds a specified time, controlling the compressor 11 to forcibly start and the outdoor fan to start. Under low-temperature conditions, the refrigerant's return gas temperature is low, and the return gas temperature cannot be used as the sole condition for exiting the anti-freeze protection mode (this may result in the inability to exit the anti-freeze protection mode, affecting the air conditioner's cooling effect). By detecting the duration of compressor 11's shutdown, and restarting the compressor 11 and outdoor fan after the shutdown duration exceeds a specified time, the normal operation of the air conditioning system is ensured, meeting the cooling requirements.

[0077] In a preferred embodiment of the present invention, the first return gas temperature threshold is -5℃ to 5℃, preferably 0℃. The second return gas temperature threshold is 6℃ to 15℃. Selecting a suitable range of the first return gas temperature threshold allows the evaporator to promptly enter the anti-freeze protection mode under low-temperature conditions, preventing evaporator icing and improving the anti-freeze performance of the air conditioning system. Selecting a suitable range of the second return gas temperature threshold allows the evaporator temperature to promptly exit the anti-freeze protection mode after rising, ensuring the normal operation of the air conditioning system and improving the user experience. It should be noted that although the embodiments of the present invention show the above-mentioned range of return gas temperature thresholds, this should not constitute a limitation on the return gas temperature range. Those skilled in the art can adjust the ranges of the first and second return gas temperature thresholds according to actual conditions.

[0078] The second embodiment of the present invention provides a refrigeration antifreeze control device for an air conditioning system, which is basically the same as the first embodiment and can be referred to the description of the first embodiment. The difference is that the above-mentioned return gas parameter is the return gas temperature.

[0079] A second embodiment of the present invention provides a computer-readable storage medium storing a computer program, which, when executed, implements the above-described cooling anti-freezing control method for an air conditioning system.

[0080] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preventing freezing in an air conditioning system, wherein the air conditioning system comprises at least a compressor, an outdoor heat exchanger, a throttling element, an indoor heat exchanger, and an outdoor fan connected in sequence to form a refrigerant circulation path, characterized in that, Includes the following steps: Preset steps: Based on the outdoor ambient temperature, preset the return air parameter compensation amount; Testing steps: In cooling mode, test the real-time return gas parameters on the low-pressure side of the air conditioning system; Comparison step: Calculate the corrected return gas parameter based on the sum of the real-time return gas parameter and the corresponding return gas parameter compensation amount, and compare whether the corrected return gas parameter is less than the first return gas parameter threshold. Control steps: If the corrected return gas parameter is less than the first return gas parameter threshold, control the air conditioning system to enter the anti-freeze protection mode. The anti-freeze protection mode is implemented as follows: The compressor and the outdoor fan corresponding to the outdoor heat exchanger are controlled to stop operating, while the indoor heat exchanger operates normally.

2. The cooling anti-freezing control method for an air conditioning system according to claim 1, characterized in that, In the preset steps, if the outdoor ambient temperature is greater than the first preset temperature, the corresponding amount of the first return air parameter compensation is applied; if the outdoor ambient temperature is greater than the second preset temperature but not greater than the first preset temperature, the corresponding amount of the second return air parameter compensation is applied. The outdoor ambient temperature is not greater than the second preset temperature. The corresponding compensation amount for the third return air parameter is as follows: the first preset temperature is greater than the second preset temperature, and the compensation amounts for the first return air parameter, the second return air parameter, and the third return air parameter increase sequentially.

3. The cooling anti-freezing control method for an air conditioning system according to claim 2, characterized in that, It also includes steps to exit the anti-freeze protection mode: Compare whether the corrected return gas parameter is greater than the second return gas parameter threshold, and the second return gas parameter threshold is greater than the first return gas parameter threshold; If the corrected return gas parameter is greater than the second return gas parameter threshold, then the compressor and the outdoor fan are controlled to start.

4. The cooling anti-freezing control method for an air conditioning system according to claim 2, characterized in that, It also includes an anti-freeze protection mode exit step: after the compressor stops running, the stop running time of the compressor is detected, and after the stop running time exceeds the specified time, the compressor is controlled to start forcibly, and the outdoor fan starts.

5. The cooling anti-freezing control method for an air conditioning system according to claim 3, characterized in that, The air conditioning system is a fixed-frequency air conditioning system. The air conditioning system also includes a temperature sensing bulb and a thermal expansion valve for detecting the return air temperature between the indoor heat exchanger and the return air end of the compressor. The first return air parameter threshold is a first return air temperature threshold, and the second return air parameter threshold is a second return air temperature threshold. The first return air temperature threshold is -5℃ to 5℃, and the second return air temperature threshold is 6℃ to 15℃.

6. The cooling anti-freezing control method for an air conditioning system according to claim 3, characterized in that, The air conditioning system is an inverter air conditioning system. The air conditioning system also includes a pressure sensor for detecting the return gas pressure between the indoor heat exchanger and the return gas end of the compressor. The first return gas parameter threshold is a first return gas pressure threshold, and the second return gas parameter threshold is a second return gas pressure threshold. The first return gas parameter threshold is 0.57MPa-0.83MPa, and the second return gas parameter threshold is 0.75MPa-1.15MPa.

7. A refrigeration anti-freeze control device for an air conditioning system, wherein the air conditioning system comprises at least a compressor, an outdoor heat exchanger, a throttling element, an indoor heat exchanger, and an outdoor fan connected in sequence to form a refrigerant circulation path, characterized in that, include: The preset module presets the return air parameter compensation amount based on the outdoor ambient temperature. The detection module detects the real-time return gas parameters on the low-pressure side of the air conditioning system in cooling mode. The comparison module calculates the corrected return gas parameter based on the sum of the real-time return gas parameter and the corresponding return gas parameter compensation amount, and compares whether the corrected return gas parameter is less than the first return gas parameter threshold. If the corrected return gas parameter is less than the first return gas parameter threshold, the control module controls the air conditioning system to enter the anti-freeze protection mode. The anti-freeze protection mode is implemented as follows: The compressor and the outdoor fan corresponding to the outdoor heat exchanger are controlled to stop operating, while the indoor heat exchanger operates normally.

8. A computer-readable storage medium, characterized in that, The system contains a computer program that, when executed, implements the refrigeration anti-freezing control method for the air conditioning system as described in any one of claims 1 to 6.

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