A control method and system for improving the reliability of oil return in high-temperature refrigeration systems of multi-split air conditioning units.

Abstract

The application provides a control method and system for improving the high-temperature refrigeration oil return reliability of a multi-connected machine, and relates to the technical field of high-temperature refrigeration oil return of a multi-connected machine. The method comprises the following steps: when the outdoor environment temperature meets the preset oil return condition, and the compressor is detected to reduce the frequency due to the high-pressure pressure or current protection in the last cooling oil return process, the control of the indoor and outdoor machines and the oil separator circuit in the multi-connected machine system is triggered; according to the starting condition, the indoor machine is controlled in a differentiated manner, the electronic expansion valve is adjusted according to the indoor temperature and the temperature sensor state, so as to obtain the indoor machine control result; and according to the indoor machine control result, the outdoor machine is controlled, including the compressor frequency adjustment and the electronic expansion valve adjustment. Through intelligent monitoring and adjustment, the oil return reliability of the multi-connected machine under the high-temperature refrigeration condition is effectively improved, and the efficient and stable operation of the system and the timely recovery of the conventional mode are ensured.

Description

Technical Field

[0001] This invention relates to the field of high-temperature refrigeration oil return technology for multi-split air conditioning systems, and in particular to a control method for improving the reliability of high-temperature refrigeration oil return in multi-split air conditioning systems. Background Technology

[0002] In existing technologies, multi-split air conditioning systems face unique challenges under high-temperature cooling conditions, especially when the external temperature exceeds 46°C. Combined with high-drop installation conditions (outdoor unit below, indoor unit above, with a height difference between 20-40m) and the large-capacity operation of indoor units (accounting for more than 70% of the outdoor unit's capacity), the system's condensing and evaporating pressures increase. This leads to an increase in compressor input power during the oil return process in the cooling room, potentially triggering high-pressure protection or current throttling mechanisms.

[0003] To ensure the system's pressure resistance reliability, when the pressure reaches a certain threshold, the system will activate high-pressure protection, reducing the compressor's operating frequency. This directly affects the oil return flow rate, as the flow rate is closely related to the compressor's operating frequency. A lower frequency means a slower flow rate, which may lead to poor oil return. To protect the compressor drive board from damage caused by excessive current, the system will automatically reduce the frequency when the current exceeds a set value. This frequency reduction also reduces the oil return flow rate, further affecting the oil return effect. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a control method for improving the reliability of oil return in high-temperature cooling of multi-split air conditioners, thereby improving the oil return reliability of multi-split air conditioners under high-temperature cooling conditions.

[0005] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows:

[0006] A first aspect is a control method for improving the reliability of oil return in high-temperature refrigeration systems of multi-split air conditioning units, the method comprising:

[0007] When the outdoor ambient temperature meets the preset oil return conditions, and it is detected that the compressor reduced its frequency due to high pressure or current protection during the last oil return process of the cold room, the control of the indoor and outdoor units and oil separator circuit of the multi-split system is triggered.

[0008] Based on the start-up conditions, the indoor unit is controlled separately, and the electronic expansion valve is adjusted according to the indoor temperature and the temperature sensor status to obtain the indoor unit control result;

[0009] Based on the indoor unit control results, control of the outdoor unit is implemented, including compressor frequency adjustment and electronic expansion valve adjustment;

[0010] While controlling the outdoor unit, control the oil separator circuit to keep a specific solenoid valve open in order to improve the oil return rate;

[0011] The system continuously monitors the oil return process and ambient temperature, and automatically reverts to normal control mode when the exit conditions are met.

[0012] Furthermore, based on the startup conditions, the indoor unit is controlled separately. The electronic expansion valve is adjusted according to the indoor temperature and the temperature sensor status to obtain the indoor unit control results, including:

[0013] Detect whether the outdoor ambient temperature, pressure, and current parameters have reached the preset start-up threshold.

[0014] After confirming that the start-up conditions are met, obtain the current status of each indoor unit, including indoor temperature, set temperature and temperature sensor status;

[0015] Based on the acquired indoor unit status information, each indoor unit is controlled separately. Indoor units with their indoor temperature sensors on and indoor temperatures below the set temperature are identified as low-temperature demand units, and their electronic expansion valves are adjusted to be closed or at minimum opening. Indoor units with their indoor temperature sensors on and indoor temperatures above the set temperature are identified as high-temperature demand units, and their overheating information is acquired.

[0016] Adjust the opening of the electronic expansion valve based on the superheat information;

[0017] Set the target range for superheat and adjust the electronic expansion valve via the controller to maintain the superheat within the target range;

[0018] The adjusted electronic expansion valve control signal is output to the corresponding indoor unit to control the indoor unit;

[0019] By controlling the output of signals, each indoor unit will adjust the refrigerant flow to obtain the corresponding indoor unit control result.

[0020] Furthermore, a target range for superheat is set, and the electronic expansion valve is adjusted via a controller to maintain the superheat within the target range, including:

[0021] Set a target range for superheat, and the range is an interval of temperature difference;

[0022] The indoor unit's indoor temperature and evaporator outlet temperature are monitored in real time by temperature sensors, and the superheat is calculated in real time based on the monitored temperature data.

[0023] The electronic expansion valve is adjusted by a preset PID controller, and the parameters of the PID controller are set and initialized, including the proportional coefficient, integral coefficient, and derivative coefficient.

[0024] The superheat data obtained from real-time calculation is input into the PID controller, which calculates the adjustment amount of the electronic expansion valve based on the set target range and the current superheat data.

[0025] The adjustment amount is converted into a corresponding control signal and output to the actuator of the electronic expansion valve;

[0026] The electronic expansion valve adjusts its opening degree according to the received control signal to regulate the flow rate of refrigerant into the evaporator;

[0027] During the control process, real-time superheat data is continuously monitored. If the superheat deviates from the target range, the controller will automatically adjust the opening of the electronic expansion valve to bring the superheat back to the target range.

[0028] Furthermore, the formula for calculating superheat is:

[0029]

[0030] Where S represents superheat; T i Indicates indoor temperature; T o Indicates the evaporator outlet temperature; SEER represents the seasonal energy efficiency ratio; 'a' represents the exponential correction factor for SEER; η e β represents the evaporator efficiency coefficient; AP represents the pressure correction factor; P represents the pressure difference. r Indicates reference pressure; K represents humidity correction factor; RH represents relative humidity; RH r Represents the reference humidity; y represents the exponential correction factor for the humidity difference; V a Indicates airflow; V r δ represents the reference airflow rate; δ represents the exponential correction factor for the airflow rate.

[0031] Furthermore, the formula for calculating the adjustment amount of the electronic expansion valve is as follows:

[0032]

[0033] Where A represents the adjustment amount of the electronic expansion valve; K represents the proportional coefficient; CD represents the difference between the current measured value and the set value; a represents the deviation index; b represents the amplitude; and ω represents the angular frequency. τ represents the initial phase; t represents the current time point; I represents the integral coefficient; DI represents the deviation integral; τ represents the integral variable; e represents the base of the natural logarithm; λ represents the decay constant; D represents the differential coefficient; d represents the differential operator; DD represents the deviation differential; c represents the differential multiplier.

[0034] Furthermore, based on the indoor unit control results, the outdoor unit is controlled, including compressor frequency adjustment and electronic expansion valve regulation, including:

[0035] Based on the indoor unit control results, analyze the current cooling capacity demand and operating status of the indoor unit;

[0036] Calculate the load that the outdoor unit will bear based on the needs of the indoor unit;

[0037] Adjust the compressor's operating frequency according to the outdoor unit's load, and adjust the opening of the electronic expansion valve according to the indoor unit's needs and the compressor's operating status.

[0038] Furthermore, the formula for calculating the load borne by the outdoor unit is as follows:

[0039]

[0040] Among them, Q o Represents the outdoor unit load; n represents the total number of indoor units; i represents the index variable; Q i E represents the cooling capacity requirement of the i-th indoor unit; i The efficiency factor of the i-th indoor unit is represented by k1, k2, k3, and k4, which are correction coefficients. o Indicates the outdoor ambient temperature; T i T represents the current indoor temperature of the i-th indoor unit; ref Indicates the temperature reference value; R o Indicates outdoor ambient humidity; R ref Indicates humidity reference value; A i Indicates the aging degree of the i-th indoor unit; A max Indicates the maximum value of the maintenance status; M i This indicates the maintenance status of the i-th indoor unit.

[0041] Secondly, a control system for improving the reliability of oil return in high-temperature refrigeration systems for multi-split air conditioning units includes:

[0042] The acquisition module is used to trigger the control of the indoor and outdoor units and oil separator circuit of the multi-split system when the outdoor ambient temperature meets the preset oil return conditions and the compressor frequency is reduced due to high pressure or current protection during the last oil return process of the cold room; according to the start-up conditions, the indoor unit is controlled separately, and the electronic expansion valve is adjusted according to the indoor temperature and the temperature sensor status to obtain the indoor unit control result;

[0043] The processing module is used to control the outdoor unit based on the indoor unit control results, including compressor frequency adjustment and electronic expansion valve adjustment; while controlling the outdoor unit, it controls the oil separator circuit to keep a specific solenoid valve open to improve the oil return rate; it continuously monitors the oil return process and ambient temperature, and automatically restores to the normal control mode when the exit conditions are met.

[0044] Thirdly, a computing device includes:

[0045] One or more processors;

[0046] A storage device for storing one or more programs that, when executed by one or more processors, cause the one or more processors to implement the method.

[0047] Fourthly, a computer-readable storage medium storing a program that, when executed by a processor, implements the method.

[0048] The above-described solution of the present invention has at least the following beneficial effects:

[0049] By triggering precise control of the indoor and outdoor units and oil separator circuits of the multi-split air conditioning system, the reliability of oil return can be improved under high-temperature refrigeration conditions. By adjusting the compressor frequency and electronic expansion valve, as well as controlling the solenoid valve of the oil separator circuit, it can be effectively ensured that lubricating oil flows back to the compressor in a timely and sufficient manner, thereby reducing the risk of compressor damage due to insufficient oil.

[0050] By differentiating and controlling the indoor units and finely adjusting the outdoor units, not only is the oil return efficiency improved, but the overall system operating efficiency and stability are also optimized. While ensuring oil return, the system's cooling effect and energy consumption control are also taken into account, achieving efficient and stable operation. Designed for specific operating conditions such as high-temperature cooling, high-drop installation, and large-capacity indoor unit operation, the system effectively enhances its adaptability and reliability under various complex conditions through real-time monitoring and adjustment of system parameters.

[0051] By continuously monitoring the oil return process and ambient temperature, and automatically reverting to the normal control mode when conditions are met, this not only improves the user's comfort experience when using the air conditioner but also extends the equipment's lifespan. It reduces maintenance and replacement costs caused by oil return issues, bringing tangible economic benefits to users. This control method enables intelligent management and maintenance of multi-split air conditioning systems. Through functions such as automatically triggering control strategies, real-time monitoring and adjustment of system parameters, and automatic restoration of the normal control mode, it reduces the need for manual intervention and improves the convenience and efficiency of system management. Attached Figure Description

[0052] Figure 1 This is a schematic flowchart of a control method for improving the reliability of oil return in high-temperature refrigeration systems provided by an embodiment of the present invention.

[0053] Figure 2 This is a schematic diagram of a control system for improving the reliability of oil return in high-temperature refrigeration of multi-split air conditioning units, provided by an embodiment of the present invention.

[0054] Figure 3 This is a structural diagram of a multi-split refrigerant system provided by an embodiment of the present invention.

[0055] Explanation of reference numerals in the attached diagram: 1. Compressor; 2. Inlet pipe; 3. Oil separator; 4. First filter; 5. Four-way valve; 6. Outdoor heat exchanger; 7. High-pressure switch; 8. Gas-liquid separator; 9. Gas pipe; 10. First electronic expansion valve; 11. First solenoid valve; 12. Capillary tube; 13. Check valve; 14. First maintenance valve; 15. First temperature sensor; 16. Plate heat exchanger; 17. Second temperature sensor; 18. Second solenoid valve; 19. Second electronic expansion valve; 20. Second filter; 21. Third temperature sensor; 22. Compressor; 23. Second maintenance valve; 24. Fourth temperature sensor; 25. Auxiliary heat exchanger. Detailed Implementation

[0056] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0057] like Figure 1 As shown in the figure, an embodiment of the present invention proposes a control method to improve the reliability of oil return in high-temperature refrigeration systems for multi-split air conditioning units. The method includes the following steps:

[0058] Step 1: When the outdoor ambient temperature meets the preset oil return conditions, and it is detected that the compressor reduced its frequency due to high pressure or current protection during the last oil return process of the cold room, the control of the indoor and outdoor units and oil separator circuit of the multi-split system is triggered.

[0059] Step 2: Based on the start-up conditions, differentiate and control the indoor unit, and adjust the electronic expansion valve according to the indoor temperature and the temperature sensor status to obtain the indoor unit control result;

[0060] Step 3: Based on the indoor unit control results, implement control of the outdoor unit, including compressor frequency adjustment and electronic expansion valve adjustment;

[0061] Step 4: While controlling the outdoor unit, control the oil separator circuit to keep a specific solenoid valve open in order to improve the oil return rate.

[0062] Step 5: Continuously monitor the oil return process and ambient temperature. When the exit conditions are met, the system will automatically return to the normal control mode.

[0063] In this embodiment of the invention, by detecting the outdoor ambient temperature and the compressor status during the previous oil return process in the cooling room, the system can intelligently trigger control of the indoor and outdoor units and the oil separator circuit. This allows the system to make adaptive adjustments based on different environmental conditions and historical operating data, improving the system's operating efficiency and stability under various circumstances. By differentially controlling the indoor units and adjusting the electronic expansion valve based on the indoor temperature and temperature sensor status, the system can more accurately meet the needs of each indoor unit. This refined control strategy not only improves the comfort of the indoor environment but also effectively reduces energy consumption. Controlling the outdoor unit based on the indoor unit control results, including adjusting the compressor frequency and regulating the electronic expansion valve, ensures coordinated operation between the outdoor and indoor units, reducing unnecessary energy consumption.

[0064] By controlling the oil separator circuit and keeping specific solenoid valves open, the system can increase the oil return rate. This helps reduce oil buildup in the system, lowers the risk of malfunctions due to oil separation issues, and extends the system's lifespan. The system continuously monitors the oil return process and ambient temperature, and automatically reverts to normal control mode when exit conditions are met. This intelligent monitoring mechanism ensures safe system shutdown under abnormal conditions, avoids potential safety hazards, and guarantees user convenience and comfort.

[0065] In a preferred embodiment of the present invention, step 1 above, when the outdoor ambient temperature meets the preset oil return conditions and it is detected that the compressor frequency was reduced due to high pressure or current protection during the last oil return process of the cooling room, triggering the control of the indoor and outdoor units and oil separator circuit of the multi-split system, may include:

[0066] In this embodiment of the invention, the system continuously monitors the outdoor ambient temperature using a temperature sensor. Once the temperature exceeds 46°C and other oil return conditions are met, the system checks historical data to confirm whether the compressor was forced to reduce its frequency due to high pressure or current issues during the last oil return process. If both conditions are met simultaneously, the control logic is activated.

[0067] In a preferred embodiment of the present invention, step 2 above, which involves differentiating and controlling the indoor unit according to the start-up conditions and adjusting the electronic expansion valve based on the indoor temperature and the temperature sensor status to obtain the indoor unit control result, may include:

[0068] Step 23: Check whether the outdoor ambient temperature, pressure, and current parameters have reached the preset start-up condition thresholds;

[0069] Step 24: After confirming that the start-up conditions are met, obtain the current status of each indoor unit, including indoor temperature, set temperature and temperature sensor status.

[0070] Step 25: Based on the obtained indoor unit status information, control each indoor unit separately, identify indoor units with indoor temperature sensors on and indoor temperatures lower than the set temperature, determine them as low-temperature demand units, and adjust the electronic expansion valve of the low-temperature demand units to the closed or minimum opening state; identify indoor units with indoor temperature sensors on and indoor temperatures higher than the set temperature, determine them as high-temperature demand units, and obtain the superheat information of the high-temperature demand units.

[0071] Step 26: Adjust the opening of the electronic expansion valve according to the superheat information;

[0072] Step 27: Set the target range for superheat and adjust the electronic expansion valve through the controller to maintain the superheat within the target range;

[0073] Step 28: Output the adjusted electronic expansion valve control signal to the corresponding indoor unit to control the indoor unit;

[0074] Step 29: By outputting control signals, each indoor unit will adjust the refrigerant flow to obtain the corresponding indoor unit control result.

[0075] In this embodiment of the invention, the start-up conditions include an outdoor ambient temperature > 46°C, meeting the oil return conditions, and the compressor reducing its frequency due to high pressure or current during the last oil return process in the cooling room. Once the start-up conditions are confirmed to be met, the system immediately acquires the current status of each indoor unit, including indoor temperature, set temperature, and temperature sensor status. Based on the acquired data, the system analyzes the status of each indoor unit, identifying indoor units with the temperature sensor on and an indoor temperature lower than (set temperature + 2°C), classifying them as low-temperature demand units; simultaneously, it identifies indoor units with the temperature sensor on and an indoor temperature higher than this threshold, classifying them as high-temperature demand units. For low-temperature demand units, the system adjusts their electronic expansion valve (EEV) to closed or at its minimum opening to reduce refrigerant flow, reduce compressor work capacity, and avoid overcooling. For high-temperature demand units, the system adjusts the opening of the electronic expansion valve based on superheat information. Superheat is a crucial parameter reflecting the refrigerant's state. The system sets a target superheat range (e.g., 4-6°C) and precisely adjusts the EEV (Extended Electric Expansion Valve) opening using a controller to maintain the superheat within this range, thus achieving efficient cooling. After adjustment, the system generates corresponding control signals and sends them to the corresponding indoor units via a communication network. Upon receiving the control signals, the indoor units interpret and execute these instructions, precisely adjusting the refrigerant flow to achieve accurate control of the indoor temperature. Throughout the control process, the system continuously monitors the actual operating status and feedback data of each indoor unit, including changes in indoor temperature, the actual opening of the electronic expansion valve, and the real-time value of superheat. Based on this feedback data, the system performs real-time analysis and optimization to ensure the effectiveness of the control strategy and stable system operation.

[0076] By differentiating and controlling the indoor units, the system can more accurately meet the cooling needs of different units. For units with low-temperature requirements, adjusting the electronic expansion valve to the closed or minimum opening state reduces unnecessary refrigerant flow, thereby lowering energy consumption. For units with high-temperature requirements, precisely adjusting the opening of the electronic expansion valve optimizes refrigerant flow and improves cooling efficiency. The system adjusts the electronic expansion valve based on the indoor temperature and temperature sensor status, ensuring the indoor temperature reaches the user-set target temperature more quickly and remains within a stable range. This enhances user comfort and avoids overheating or underheating. By setting a target range for superheat and precisely adjusting the electronic expansion valve through the controller, superheat is maintained within the target range, effectively preventing system malfunctions due to excessively high or low superheat. This enhances system stability and reliability, reducing maintenance and repair costs. The entire control process is based on real-time data monitoring and intelligent algorithm decision-making, achieving intelligent control of the indoor units. This not only simplifies user operation but also enables the system to automatically adapt to different environmental conditions and usage needs.

[0077] In a preferred embodiment of the present invention, step 27, which involves setting a target range for superheat and adjusting the electronic expansion valve via a controller to maintain the superheat within the target range, may include:

[0078] Step 271: Set a target range for superheat, and the range is an interval of temperature difference;

[0079] Step 272: Monitor the indoor temperature of the indoor unit and the evaporator outlet temperature in real time using a temperature sensor, and calculate the superheat in real time based on the monitored temperature data.

[0080] Step 273: Adjust the electronic expansion valve through the preset PID controller, and set and initialize the parameters of the PID controller, including the proportional coefficient, integral coefficient, and derivative coefficient.

[0081] Step 274: Input the superheat data obtained in real time into the PID controller. The controller calculates the adjustment amount of the electronic expansion valve based on the set target range and the current superheat data.

[0082] Step 275: Convert the adjustment amount into a corresponding control signal and output it to the actuator of the electronic expansion valve;

[0083] Step 276: The electronic expansion valve adjusts its opening according to the received control signal to adjust the flow rate of refrigerant into the evaporator;

[0084] Step 277: During the control process, the real-time superheat data is continuously monitored. If the superheat deviates from the target range, the controller will automatically adjust the opening of the electronic expansion valve to bring the superheat back to the target range.

[0085] In this embodiment of the invention, the system sets a target range for superheat, which is a specific temperature difference interval (e.g., 4℃-6℃). Using a temperature sensor installed inside the indoor unit, the system monitors the indoor temperature and the evaporator outlet temperature in real time. These two temperature values ​​are key parameters for calculating superheat. Based on the monitored indoor and evaporator outlet temperatures, the system calculates the superheat in real time. Superheat is the difference between the evaporator outlet temperature and the indoor temperature, reflecting the evaporation of the refrigerant inside the evaporator. The system uses a preset PID (proportional-integral-derivative) controller to adjust the electronic expansion valve. Before use, the PID controller needs to be parameter-set and initialized, including the proportional coefficient, integral coefficient, and derivative coefficient. These parameter settings directly affect the controller's performance and response speed. The real-time calculated superheat data is input into the PID controller, which calculates the adjustment amount based on the set target range and the current superheat value. Then, the PID controller converts this adjustment amount into a corresponding control signal and outputs it to the actuator of the electronic expansion valve. The magnitude and direction of the control signal determine the adjustment method and amplitude of the electronic expansion valve opening.

[0086] After receiving the control signal from the PID controller, the electronic expansion valve adjusts its opening degree accordingly. The change in the electronic expansion valve's opening directly affects the refrigerant flow rate into the evaporator. When the electronic expansion valve opening increases, the refrigerant flow rate increases; when the opening decreases, the refrigerant flow rate decreases. In this way, the system can precisely control the refrigerant evaporation process inside the evaporator. Throughout the control process, the system continuously monitors real-time superheat data. If the superheat deviates from the set target range, the PID controller will automatically adjust the opening of the electronic expansion valve to bring the superheat back within the target range. This continuous monitoring and automatic adjustment mechanism ensures stable and efficient system operation, always maintaining the superheat within the set target range.

[0087] By setting a target range for superheat and monitoring and adjusting it in real time, the system can be ensured to operate stably under different loads and external conditions. Superheat is a key parameter reflecting the operating status of the refrigeration system; maintaining it within the target range helps reduce system fluctuations and instability. The PID controller precisely adjusts the opening of the electronic expansion valve based on real-time superheat data, thereby controlling the flow of refrigerant into the evaporator. This precise control ensures efficient refrigerant utilization, reduces energy consumption, and improves the overall energy efficiency of the system. Maintaining superheat within the target range means more precise and stable indoor temperature control. This helps provide a consistent and comfortable environment, reducing discomfort caused by temperature fluctuations. By reducing overheating or undercooling, thermal and mechanical stresses on system components (such as compressors and evaporators) can be reduced, thereby extending the service life of these critical components. Stable superheat control reduces the frequency of system failures, lowering maintenance requirements and related costs. Furthermore, real-time monitoring and automatic adjustment allow for the timely detection and handling of potential problems, preventing small issues from escalating into major malfunctions. Automated systems eliminate the need for frequent manual adjustments by users, simplifying the operation process. At the same time, stable indoor temperature and efficient energy consumption can also improve users' overall satisfaction with the air conditioning system.

[0088] In a preferred embodiment of the present invention, the formula for calculating superheat is:

[0089]

[0090] Where S represents superheat; T i Indicates indoor temperature; T o Indicates the evaporator outlet temperature; SEER represents the seasonal energy efficiency ratio; 'a' represents the exponential correction factor for SEER; η e β represents the evaporator efficiency coefficient; β represents the pressure correction factor; ΔP represents the pressure difference; P r Indicates reference pressure; K represents humidity correction factor; RH represents relative humidity; RH r Represents the reference humidity; y represents the exponential correction factor for the humidity difference; V a Indicates airflow; V r δ represents the reference airflow rate; δ represents the exponential correction factor for the airflow rate.

[0091] In this embodiment of the invention, the basic calculation of superheat begins with the indoor temperature (T). i ) and evaporator outlet temperature (T) oThe difference between the base temperature difference and the evaporator temperature coefficient (η) reflects the heat absorbed by the refrigerant during evaporation inside the evaporator and is a core component of superheat calculations. The Seasonal Energy Efficiency Ratio (SEER) and its exponential correction factor (α) are used to adjust for the base temperature difference to reflect system performance variations under different SEER conditions. Systems with a high SEER utilize the temperature difference more effectively to produce a cooling effect. e The influence of evaporator performance on superheat was considered. A high-efficiency evaporator can better convert temperature difference into cooling capacity, thus affecting the magnitude of superheat. The pressure correction factor (β) is related to the pressure difference (ΔP) and the reference pressure (P). r Together, these are used to adjust superheat to reflect the effect of internal system pressure changes on the evaporation process. Changes in pressure difference alter the refrigerant evaporation rate, thus affecting superheat. The humidity correction factor (K) is used in conjunction with relative humidity (RH) and reference humidity (RH). r The difference in humidity, along with the exponential correction factor (y) for the humidity difference, is used to account for the impact of ambient humidity on superheat. Changes in humidity affect the latent heat capacity of the air, thus affecting the cooling effect and superheat of the evaporator. Airflow (V a ) and reference airflow (V r The exponential correction factor (δ) for airflow rate is used to account for the effect of airflow rate across the evaporator on superheat. Changes in airflow rate directly affect the heat exchange efficiency of the evaporator surface, thus affecting superheat.

[0092] By using the Seasonal Energy Efficiency Ratio (SEER) and its exponential correction factor (a), the calculation of superheat can be adjusted according to different SEER conditions, thereby optimizing the system's energy efficiency. This helps achieve more efficient cooling, reduce energy consumption, and improve overall energy-saving performance. Evaporator efficiency coefficient (ηe), pressure correction factor (β), pressure difference (ΔP), and reference pressure (P) are also considered. r Factors such as humidity correction factor (K), relative humidity (RH), and reference humidity (RH) work together to enable the system to maintain a stable superheat under different operating conditions. This helps reduce system fluctuations and failure rates, and improves operational reliability. r The humidity difference and its exponential correction factor (y) accurately reflect the impact of ambient humidity on superheat. Airflow (V) a ) and reference airflow (V r The system incorporates an exponential correction factor (δ) for airflow, enabling it to adjust superheat based on changes in airflow. This facilitates more precise airflow control, improving system response speed and adjustment accuracy.

[0093] In a preferred embodiment of the present invention, the formula for calculating the adjustment amount of the electronic expansion valve is as follows:

[0094]

[0095] Where A represents the adjustment amount of the electronic expansion valve; K represents the proportional coefficient; CD represents the difference between the current measured value and the set value; a represents the deviation index; b represents the amplitude; and ω represents the angular frequency. τ represents the initial phase; t represents the current time point; I represents the integral coefficient; DI represents the deviation integral; τ represents the integral variable; e represents the base of the natural logarithm; λ represents the decay constant; D represents the differential coefficient; d represents the differential operator; DD represents the deviation differential; c represents the differential multiplier.

[0096] In this embodiment of the invention, the proportionality coefficient (K) is multiplied by a deviation index (a) correction value for the difference (CD) between the current measured value and the set value, and then a sinusoidal fluctuation term is added to introduce periodic adjustments. This sinusoidal fluctuation consists of amplitude (b), angular frequency (ω), and initial phase. The decision can be adjusted according to system needs to cope with specific periodic disturbances. The proportional coefficient K determines the speed and intensity of the response. The integral coefficient (I) is multiplied by the integral value of past deviations, which takes into account all deviations from time 0 to the current time point t, and gradually reduces the influence of past deviations according to the decay constant (λ). This helps to eliminate the steady-state error of the system; even with continuous small deviations, the integral term gradually accumulates, pushing the system to the setpoint. Integral control makes more detailed adjustments to the system by considering historical deviation information, which helps to improve the stability and accuracy of the system. The derivative coefficient (D) is multiplied by the differential value of the deviation (i.e., the rate of change of the deviation) and the sum of the differential multiplier (c). Derivative control focuses on the trend of deviation changes, can predict possible future deviations, and make adjustments in advance. When the system approaches the setpoint, derivative control can reduce overshoot and improve the system's response speed and stability.

[0097] The proportional control section (composed of the proportional coefficient K and the difference CD between the current measured value and the setpoint) ensures that the system reacts quickly to deviations, reducing settling time and improving control accuracy. The integral control section (integrating historical deviations through the integral coefficient I) helps eliminate steady-state errors; even with continuous small deviations, the cumulative effect of the integral term drives the system to reach and stabilize at the setpoint. The derivative control section (responding to the rate of change of deviation through the derivative coefficient D) predicts future deviation trends and makes adjustments in advance, thereby reducing system overshoot and oscillations, and improving the system's dynamic performance and stability. The sinusoidal oscillation term (composed of amplitude b, angular frequency ω, and initial phase)... The system (within the defined parameters) allows for compensation against specific periodic disturbances. Multiple parameters (such as the proportional coefficient K, integral coefficient I, derivative coefficient D, and deviation exponent a) can be adjusted according to specific application scenarios and system requirements, providing a wide range of adjustment and flexibility. By comprehensively considering current deviations, historical deviations, and deviation trends, the system's state can be more comprehensively assessed, and more reasonable adjustment decisions can be made, thereby enhancing the system's stability and reliability.

[0098] In a preferred embodiment of the present invention, step 3 above, which involves controlling the outdoor unit based on the indoor unit control result, including compressor frequency adjustment and electronic expansion valve adjustment, may include:

[0099] Step 31: Based on the indoor unit control results, analyze the current cooling capacity demand and operating status of the indoor unit;

[0100] Step 32: Calculate the load that the outdoor unit will bear based on the needs of the indoor unit;

[0101] Step 33: Adjust the compressor's operating frequency according to the outdoor unit load, and adjust the opening of the electronic expansion valve according to the indoor unit's needs and the compressor's operating status.

[0102] In this embodiment of the invention, the indoor unit's control system monitors environmental parameters such as room temperature and humidity in real time, as well as the indoor unit's operating status, such as fan speed and refrigerant temperature. By comparing set values ​​with actual values, the system can accurately determine the current cooling demand and assess whether the indoor unit's operating status is good. Based on the indoor unit's cooling demand and operating status, the control system calculates the load that the outdoor unit needs to bear. This calculation process comprehensively considers multiple factors, including the indoor-outdoor temperature difference, the room's heat load, and the system's energy efficiency ratio. Through precise load calculation, it can be ensured that the cooling output of the outdoor unit matches the demand of the indoor unit. According to the load borne by the outdoor unit, the control system sends instructions to the compressor to adjust its operating frequency. With the support of inverter technology, the compressor's frequency can be continuously adjusted within a certain range to achieve precise cooling output. When the indoor cooling demand increases, the compressor will increase its operating frequency and increase the refrigerant circulation, thereby improving cooling capacity; conversely, when the demand decreases, it will decrease its operating frequency to save energy and maintain the stability of the indoor environment.

[0103] The electronic expansion valve is a key component for controlling refrigerant flow. Based on the indoor unit's requirements and the compressor's operating status, the control system precisely adjusts the opening of the electronic expansion valve. Specifically, for indoor units meeting certain conditions (such as the indoor temperature sensor being ON and the return air temperature being below the set temperature by a certain range), the electronic expansion valve will maintain a specific opening (e.g., 0 step) to ensure stable refrigerant flow and cooling effect. For indoor units under other conditions, the opening of the electronic expansion valve is controlled according to the superheat value. The superheat value is the difference between the refrigerant gas temperature at the evaporator outlet and the refrigerant liquid temperature at the evaporator inlet; it reflects the evaporator's heat exchange efficiency. By adjusting the opening of the electronic expansion valve, the refrigerant flow rate in the evaporator can be controlled, thereby adjusting the superheat value (B value) to achieve a highly efficient cooling effect.

[0104] By analyzing the current cooling demand and operating status based on the indoor unit's control results, the system can more accurately understand actual needs, thus avoiding over-cooling or under-cooling and improving the user experience. Adjusting the compressor's operating frequency according to the load borne by the outdoor unit ensures that the compressor operates at its optimal efficiency point, reducing energy consumption. Simultaneously, adjusting the opening of the electronic expansion valve optimizes refrigerant flow, further improving the system's energy efficiency ratio and achieving energy-saving goals. Through fine-tuning of the compressor frequency and electronic expansion valve, the system can better adapt to various operating conditions, including high-temperature environments and special situations such as oil return processes. This helps reduce equipment failure rates and improves system stability and reliability.

[0105] In a preferred embodiment of the present invention, the formula for calculating the load borne by the outdoor unit is:

[0106]

[0107] Among them, Q o Represents the outdoor unit load; n represents the total number of indoor units; i represents the index variable; Q i E represents the cooling capacity requirement of the i-th indoor unit; i The efficiency factor of the i-th indoor unit is represented by k1, k2, k3, and k4, which are correction coefficients. o Indicates the outdoor ambient temperature; T i T represents the current indoor temperature of the i-th indoor unit; ref Indicates the temperature reference value; R o Indicates outdoor ambient humidity; R ref Indicates humidity reference value; A i Indicates the aging degree of the i-th indoor unit; A max Indicates the maximum value of the maintenance status; M i This indicates the maintenance status of the i-th indoor unit.

[0108] In this embodiment of the invention, each indoor unit is configured according to its own cooling capacity requirement (Q). i ) and efficiency factor (E) i This contributes to the outdoor unit load. Cooling demand reflects the cooling capacity required by the indoor unit to maintain the set temperature, while the efficiency factor reflects the energy efficiency performance of the indoor unit during operation. This is achieved by comparing the outdoor ambient temperature (T...). o ) and the current indoor temperature (T) of each indoor unit i ), and combined with the temperature reference value (T) ref This is used to calculate a temperature correction term. This reflects the direct impact of outdoor temperature changes on the cooling load. Outdoor ambient humidity (R) o ) and humidity reference value (R ref The difference between the humidity levels is adjusted in the load calculation using a humidity correction factor (k2). Humidity has a significant impact on cooling performance and load, especially in high-humidity environments. i This represents the aging degree of the i-th indoor unit, an indicator reflecting the performance degradation of the indoor unit over time. The formula for calculating the aging degree of the indoor unit is: Among them, A i Indicates the degree of aging; t i t represents the actual service life of the i-th indoor unit; max Indicates the design lifespan of the indoor unit; A max This indicates the maximum degree of aging of the indoor unit.

[0109] The actual service life t of the i-th indoor unit i This refers to the number of years that have elapsed since installation. This time is cumulative and increases with continued use of the indoor unit. max This indicates the design life of the indoor unit, which is the maximum number of years the indoor unit is expected to maintain stable performance and meet design requirements under normal operating conditions. Design life serves as the benchmark for assessing indoor unit performance degradation. max This indicates the maximum degree of aging of the indoor unit, taken as 1 (or 100%, depending on the specific application). It represents the lowest level of performance degradation the indoor unit will reach when it reaches its designed lifespan, i.e., the fully aged state. A i Based on actual service life t i With design service life t max The ratio, multiplied by the maximum aging degree A max This value is calculated and reflects the current aging level of the i-th indoor unit, that is, the relative proportion of performance degradation.

[0110] When t i When A = 0, i =0 indicates that the indoor unit is brand new and has not aged.

[0111] When t i =t max At that time, A i =A max This indicates that the indoor unit has reached its designed lifespan and its performance has degraded to the maximum extent.

[0112] In 0 <t i <t max Within the range, A i The value of t varies with t i The linear increase in the value indicates that the performance of the indoor unit gradually declines over time.

[0113] The degree of aging of each indoor unit (A) i ) was taken into consideration, by comparing it with the maximum value of the maintenance condition (A) max A comparison is made to calculate an aging correction term. This reflects the impact of equipment aging over time on performance and load. Indoor unit maintenance status (M) i It also relates to the maximum value of the maintenance status (M) max The comparison is used for correction. Good maintenance can maintain equipment performance and reduce unnecessary load.

[0114] Taking into account multiple factors such as the cooling capacity requirement, efficiency, ambient temperature and humidity, equipment aging, and maintenance status of the indoor unit, the system can accurately calculate the load that the outdoor unit needs to handle. This helps avoid overloading or underloading, ensuring the stable operation of the refrigeration system. By incorporating factors such as the efficiency factor and aging status of the indoor unit, it reflects changes in equipment performance over time, thus helping managers formulate reasonable energy management strategies. For example, for less efficient indoor units, timely maintenance or replacement can be performed to reduce overall energy consumption. Temperature and humidity correction terms consider the impact of outdoor ambient temperature and humidity on the cooling load. This allows the system to better adapt to different environmental conditions, especially maintaining stable operation under extreme weather conditions. By considering the aging status and maintenance status of the indoor unit, the formula can remind managers to perform timely maintenance and upkeep. This helps extend the lifespan of the equipment and reduce downtime caused by equipment failure.

[0115] In a preferred embodiment of the present invention, step 4 above, which involves controlling the oil separator circuit while controlling the outdoor unit to keep a specific solenoid valve open in order to improve the oil return rate, may include:

[0116] The oil separator circuit is a crucial part of the refrigeration system, responsible for effectively separating the oil-gas mixture discharged from the compressor. Through this circuit, the system ensures that lubricating oil returns to the compressor in a timely manner, maintaining its normal lubrication and cooling functions, while preventing excessive oil from entering the refrigeration cycle and affecting efficiency. During the oil return process, when the system detects the need for oil return (e.g., based on parameters such as time, pressure, or oil level), the control logic issues a command to keep the first solenoid valve (SV6) open. This allows the oil-gas mixture to smoothly enter the oil separator for separation. The outdoor unit control unit monitors the operating status of the entire refrigeration system and adjusts parameters such as compressor frequency and refrigerant flow rate as needed. During the oil return phase, the outdoor unit control unit works closely with the first solenoid valve (SV6) to maximize oil return efficiency without affecting the normal operation of the system.

[0117] By keeping the first solenoid valve (SV6) open, the oil separator can continuously and efficiently process the incoming oil-gas mixture. The separated oil is quickly returned to the compressor through a dedicated return line, significantly improving the return rate. This improved mechanism helps reduce the oil's residence time in the system, lowering the risk of oil oxidation and contamination. During control, the system monitors key parameters (such as pressure, temperature, and oil level) in real time to ensure the safety of the return operation and the stability of the entire refrigeration system. If an abnormality is detected (such as excessively high or low pressure), the control logic immediately adjusts the state of the first solenoid valve (SV6) or triggers protective measures to prevent potential malfunctions. Modern refrigeration systems are equipped with advanced intelligent management functions that can automatically adjust the return strategy based on actual conditions. For example, the system can predict the optimal timing and duration of the return based on historical data and current environmental conditions, thereby further optimizing the control logic of the first solenoid valve (SV6) and the return efficiency.

[0118] In a preferred embodiment of the present invention, step 5 above, which involves continuously monitoring the oil return process and ambient temperature, and automatically resuming the system to normal control mode when the exit conditions are met, may include:

[0119] The system collects real-time data on oil temperature, oil pressure, oil level, refrigerant temperature, pressure, and ambient temperature using sensors placed at key locations (such as the compressor outlet, oil separator inlet and outlet, and indoor and outdoor units). This data is transmitted to the control unit for analysis and processing. During the oil return process, the control unit pays particular attention to the efficiency of the oil separator, the oil return rate, and the pressure and temperature in the oil return pipeline. By comparing preset standard values ​​or historical data, the system can assess whether the oil return process is proceeding smoothly and promptly identify potential anomalies or malfunctions. The system continuously monitors the ambient temperature using an outdoor temperature sensor and adjusts the control strategy according to temperature changes. Especially in high-temperature environments, the system closely monitors the compressor's operating status and cooling effect to ensure it is not damaged by overheating. The system determines whether to terminate the oil return control mode based on preset exit conditions. These conditions may include: the oil return time reaching a preset value, the oil level returning to the normal range, the compressor current or pressure returning to normal, and the ambient temperature dropping to a safe range. When any of these conditions is met, the control unit issues a command to switch to the normal control mode.

[0120] Once the system determines that it needs to exit the oil return control mode, the control unit will gradually adjust parameters such as compressor frequency, electronic expansion valve opening, and fan speed to smoothly transition the system to the normal control mode. During this process, the system will continue to monitor various key indicators to ensure the stability and safety of the transition. If any abnormalities or signs of malfunction are detected during monitoring (such as low oil pressure, high oil temperature, compressor overload, etc.), the system will immediately trigger protective measures, such as shutdown, frequency reduction, or closure of specific valves, to prevent the fault from escalating and protect critical components from damage.

[0121] like Figure 2 As shown, embodiments of the present invention also provide a control system 20 for the reliability of oil return in high-temperature refrigeration of multi-split air conditioning systems, comprising:

[0122] The acquisition module 21 is used to trigger the control of the indoor and outdoor units and oil separator circuit of the multi-split system when the outdoor ambient temperature meets the preset oil return conditions and the compressor frequency is reduced due to high pressure or current protection during the last oil return process of the cold room; according to the start-up conditions, the indoor unit is controlled separately, and the electronic expansion valve is adjusted according to the indoor temperature and the temperature sensor status to obtain the indoor unit control result;

[0123] The processing module 22 is used to control the outdoor unit based on the indoor unit control results, including compressor frequency adjustment and electronic expansion valve adjustment; while controlling the outdoor unit, it controls the oil separator circuit to keep a specific solenoid valve open to improve the oil return rate; it continuously monitors the oil return process and ambient temperature, and when the exit conditions are met, the system automatically returns to the normal control mode.

[0124] like Figure 3As shown, embodiments of the present invention also provide a multi-split refrigerant system, comprising:

[0125] Compressor 1 draws in low-pressure gaseous refrigerant and compresses it into high-temperature, high-pressure gaseous refrigerant;

[0126] Intake pipe 2, one end of which is connected to compressor 1;

[0127] Oil separator 3 is connected to the other end of the air inlet pipe 2 and receives high-temperature and high-pressure gaseous refrigerant from compressor 1;

[0128] The first filter 4 is connected to the oil separator 3, receives and removes impurities and particulate matter present in the high-temperature and high-pressure gaseous refrigerant in the oil separator 3, and the separated lubricating oil is returned to the compressor 1 through the oil return pipe;

[0129] The gas-liquid separator 8 is connected to the compressor 1 via a liquid pipe;

[0130] Four-way valve 5 is used to guide the pure gaseous refrigerant separated in oil separator 3 and the liquid component in the gaseous refrigerant in gas-liquid separator 8.

[0131] The outdoor heat exchanger 6 receives the pure gaseous refrigerant separated in the oil separator 3 guided by the four-way valve 5, and exchanges heat with the external environment to condense it into liquid refrigerant.

[0132] The first electronic expansion valve 10 is connected to the outdoor heat exchanger 6 and controls the flow rate of refrigerant from the high-pressure side to the low-pressure side.

[0133] The gas pipe 9 receives the liquid component of the gaseous refrigerant in the gas-liquid separator 8, which is guided by the four-way valve 5.

[0134] In this embodiment of the invention, compressor 1 starts working, drawing in low-pressure gaseous refrigerant and compressing it into high-temperature, high-pressure gaseous refrigerant. The high-temperature, high-pressure gaseous refrigerant enters oil separator 3 through inlet pipe 2, where oil separator 3 effectively separates the lubricating oil from the refrigerant. The separated high-temperature, high-pressure pure gaseous refrigerant then flows into first filter 4, which further removes any impurities and particulate matter, ensuring the purity of the refrigerant. Simultaneously, the separated lubricating oil returns to compressor 1 through oil return pipe, achieving lubricant recycling. The filtered pure gaseous refrigerant then enters four-way valve 5, which guides the pure gaseous refrigerant to the outdoor heat exchanger 6 according to system requirements. In the outdoor heat exchanger 6, the pure gaseous refrigerant exchanges heat with the external environment, releasing heat and condensing into liquid refrigerant. First electronic expansion valve 10 is connected to outdoor heat exchanger 6, precisely controlling the flow rate of liquid refrigerant from the high-pressure side to the low-pressure side, ensuring stable system operation and achieving efficient cooling. Meanwhile, the gas-liquid separator 8 is connected to the compressor 1 via a liquid pipe to separate any liquid refrigerant that may be present in the system, preventing it from entering the compressor and causing damage. The liquid components in the separated gaseous refrigerant are then recovered and reused via the gas pipe 9, guided by the four-way valve 5.

[0135] Through high-temperature, high-pressure compression by the compressor and precise flow control by the first electronic expansion valve, the system achieves rapid and efficient cooling. The combined use of an oil separator and a first filter effectively removes lubricating oil, impurities, and particulate matter from the refrigerant, ensuring refrigerant purity and stable system operation. The oil return pipe enables lubricating oil recycling, reducing lubricant consumption and lowering system maintenance costs. The gas-liquid separator effectively prevents liquid refrigerant from entering the compressor, extending compressor lifespan and improving system safety. The four-way valve design allows the system to flexibly switch refrigerant flow direction according to actual needs, enabling rapid adjustment of the cooling mode.

[0136] like Figure 3 As shown, the compressor 1 is equipped with a fourth temperature sensor 24.

[0137] In this embodiment of the invention, compressor 1 is the core component, responsible for compressing the refrigerant gas and increasing its temperature and pressure. A fourth temperature sensor 24 is installed on compressor 1 to monitor its operating temperature in real time. Based on the thermistor effect, the fourth temperature sensor 24 can sense temperature changes in the compressor 1's casing or internal cooling medium and convert these temperature signals into electrical signals. These electrical signals are then transmitted to the system's control unit to determine whether the compressor's operating status is normal and whether adjustments to operating parameters are needed to ensure stable system operation.

[0138] The fourth temperature sensor 24 can monitor the operating temperature of compressor 1 in real time, thereby ensuring that the compressor operates within a safe temperature range. Once the temperature exceeds a preset threshold, the control unit can respond quickly, such as adjusting the compressor's operating frequency or starting the cooling fan, to prevent damage to the compressor due to overheating. By accurately monitoring the compressor's temperature, the system can more intelligently adjust the compressor's operating status, minimizing energy consumption while meeting cooling or heating needs. For example, at lower temperatures, the compressor's operating frequency can be appropriately reduced to decrease unnecessary energy consumption.

[0139] like Figure 3 As shown, a high-pressure switch 7 is provided on the air intake pipe 2.

[0140] In this embodiment of the invention, a high-pressure switch 7 is added to the intake pipe 2. This high-pressure switch 7 is a safety protection device used to monitor the pressure of the refrigerant in the system. When the compressor 1 is running, it draws in low-pressure gaseous refrigerant and compresses it into high-temperature, high-pressure gaseous refrigerant, which then flows through the intake pipe 2. During this process, if the pressure in the intake pipe 2 abnormally increases due to some reason (such as system blockage, excessive refrigerant, etc.) and exceeds the set threshold of the high-pressure switch 7, the high-pressure switch 7 will be triggered immediately. Once the high-pressure switch 7 is triggered, it will cut off the power supply to the system or issue an alarm signal, thereby stopping the operation of the compressor 1 and other related components to prevent the system from being damaged due to excessive pressure.

[0141] The high-pressure switch 7 provides an additional layer of safety for the system. When the refrigerant pressure rises abnormally, it can promptly cut off the power or issue an alarm, preventing damage to the system due to high pressure and protecting core components such as the compressor. Because the high-pressure switch 7 can respond promptly and stop abnormal system operation, it helps reduce repair and replacement costs caused by system damage. By monitoring and controlling refrigerant pressure, the high-pressure switch 7 helps maintain stable system operation. It can intervene promptly when pressure is abnormal, preventing further deterioration and ensuring system reliability and efficiency.

[0142] like Figure 3 As shown, the lubricating oil filtered by the first filter 4 flows back to the compressor 1 through the first solenoid valve 11 and the capillary tube 12.

[0143] In this embodiment of the invention, when the high-temperature, high-pressure gaseous refrigerant flows through the first filter 4, the lubricating oil is effectively separated. The separated lubricating oil then enters the first solenoid valve 11. The first solenoid valve 11 acts as a control element, precisely opening or closing according to system needs to control the flow of lubricating oil. When the first solenoid valve 11 is open, the lubricating oil flows through the capillary tube 12. The capillary tube 12 acts as a throttling and pressure-reducing agent, smoothly transitioning the lubricating oil from a high-pressure state to a low-pressure state, while also helping to control the flow rate of the lubricating oil. After being throttled and pressure-reduced by the capillary tube 12, the lubricating oil finally flows back to the compressor 1, providing the necessary lubrication and cooling to ensure its stable operation.

[0144] The combined design of the first filter 4, the first solenoid valve 11, and the capillary tube 12 achieves effective separation and recycling of lubricating oil. This not only reduces lubricating oil consumption but also lowers system operating costs. The introduction of the first solenoid valve 11 allows for precise control of lubricating oil flow. The system can adjust the opening and closing state of the solenoid valve according to actual needs, ensuring that lubricating oil is delivered to the compressor at the appropriate time and in the appropriate amount. Timely return of lubricating oil provides continuous lubrication and cooling to the compressor, helping to reduce compressor wear and overheating. Through the throttling and pressure reduction effect of the capillary tube 12, the lubricating oil can smoothly transition and reduce energy loss during the return process. This helps to improve the overall energy efficiency ratio of the system, achieving more energy-efficient and high-performance operation.

[0145] like Figure 3 As shown, the oil separator 3 is connected to the four-way valve 5 via a liquid pipe equipped with a check valve 13 and a first maintenance valve 14.

[0146] In this embodiment of the invention, the one-way valve 13 is a valve that allows refrigerant to flow only in one direction. Under normal operating conditions, the liquid refrigerant separated by the oil separator 3 flows to the four-way valve 5 through the one-way valve 13. The one-way valve 13 ensures that the refrigerant can only flow towards the four-way valve 5, preventing backflow due to pressure changes or improper operation. The first maintenance valve 14 is an automatically controllable valve used for system inspection and maintenance. When the system requires inspection or maintenance, the liquid pipe section between the oil separator 3 and the four-way valve 5 can be isolated by closing the first maintenance valve 14, facilitating inspection, repair, or replacement of this pipe section or related components. During normal system operation, the first maintenance valve 14 remains open to ensure smooth refrigerant flow.

[0147] The one-way valve 13 effectively prevents refrigerant backflow, ensuring the directionality and stability of refrigerant flow within the system. This helps avoid system performance degradation caused by backflow. The introduction of the first maintenance valve 14 allows for easy isolation of specific pipeline sections when maintenance or repair is required. This not only simplifies the maintenance process but also reduces system downtime due to maintenance, improving system maintainability and operational efficiency. The combined use of the one-way valve 13 and the first maintenance valve 14 enhances system safety. The one-way valve prevents backflow, reducing the risk of accidents; while the maintenance valve ensures that the connection of the problematic pipeline can be quickly disconnected in an emergency, protecting other parts of the system from impact.

[0148] like Figure 3 As shown, the outdoor heat exchanger 6 is equipped with a first temperature sensor 15.

[0149] In this embodiment of the invention, a first temperature sensor 15 is installed on the outdoor heat exchanger 6 in the multi-split refrigerant system. This temperature sensor is used to monitor the surface temperature of the outdoor heat exchanger 6 in real time. When the system is running, the refrigerant in the outdoor heat exchanger 6 exchanges heat with the external environment, releasing or absorbing heat. During this process, the first temperature sensor 15 continuously monitors temperature changes. The first temperature sensor 15 converts the detected temperature signal into an electrical signal and then transmits it to the system's control unit. After receiving the temperature signal, the control unit determines whether the current temperature is within the normal range according to preset control logic and adjusts the system's operating state accordingly, such as adjusting the compressor's output power and changing the opening of the electronic expansion valve, to ensure efficient and safe system operation.

[0150] Through real-time monitoring by the first temperature sensor 15, the system can more accurately control the operating status of the outdoor heat exchanger 6, thereby ensuring that the refrigerant exchanges heat within the optimal temperature range and improving system efficiency and performance. Based on the temperature data fed back by the first temperature sensor 15, the system can intelligently adjust its operating status to avoid unnecessary energy consumption, thus achieving energy-saving and environmentally friendly effects. The real-time monitoring by the temperature sensor helps to promptly detect abnormal temperature conditions, such as excessively high or low temperatures, thereby triggering the system's protection mechanism to prevent equipment damage or safety accidents caused by abnormal temperatures.

[0151] like Figure 3 As shown, the first electronic expansion valve 10 is connected to the auxiliary heat exchanger 25.

[0152] In this embodiment of the invention, the first electronic expansion valve 10 is connected not only to the outdoor heat exchanger 6 but also to the auxiliary heat exchanger 25. The auxiliary heat exchanger 25 is used to provide additional heating or cooling capacity under specific conditions (such as low-temperature environments). The first electronic expansion valve 10 plays a crucial role here, controlling the flow rate of refrigerant from the high-pressure side to the low-pressure side, and also regulating the amount of refrigerant entering the auxiliary heat exchanger 25. When the system requires auxiliary heating, the control unit determines this based on feedback signals from temperature sensors (such as the first temperature sensor 15). Based on the determination result, the control unit sends a command to the first electronic expansion valve 10 to adjust its opening. In this way, the first electronic expansion valve 10 can accurately control the flow rate of refrigerant to the auxiliary heat exchanger 25. After receiving an appropriate amount of refrigerant, the auxiliary heat exchanger 25 exchanges heat with the external environment, providing the required additional heating. The refrigerant after heat exchange returns to the system for reuse.

[0153] By cooperating with the auxiliary heat exchanger, the system can operate efficiently under a wider range of temperature and environmental conditions, enhancing its adaptability. The precise control of the first electronic expansion valve 10 ensures that only the necessary amount of refrigerant flows to the auxiliary heat exchanger, reducing unnecessary energy consumption and thus improving the system's energy efficiency ratio. Due to the fast response speed of the first electronic expansion valve 10, the system can quickly adjust the operating state of the auxiliary heat exchanger to meet sudden changes in load demand. By rationally configuring the first electronic expansion valve 10 and the auxiliary heat exchanger, the overall system layout can be optimized, resulting in smoother refrigerant flow and reduced pressure loss and energy consumption.

[0154] like Figure 3 As shown, the gas-liquid separator 8 is connected to the plate heat exchanger 16, and the gas-liquid separator 8 is equipped with a second solenoid valve 18.

[0155] In this embodiment of the invention, the gas-liquid separator 8 plays a crucial role in maintaining the stability of the refrigerant state. Its connection with the plate heat exchanger 16 forms an important path for refrigerant circulation in the system. The main function of the gas-liquid separator 8 is to separate the incoming refrigerant into liquid and gaseous forms, ensuring that the liquid and gaseous refrigerants enter their respective pipes, thereby maintaining the normal operation of the system. Simultaneously, the second solenoid valve 18 installed on the gas-liquid separator 8 controls the refrigerant flow. When the system needs to adjust the refrigerant flow rate or direction, the second solenoid valve 18 opens or closes according to the instructions of the control system. This precise control capability allows the system to flexibly adjust the refrigerant circulation state according to actual needs. The plate heat exchanger 16, as another important component of the system, performs heat exchange. The refrigerant flowing out of the gas-liquid separator 8 enters the plate heat exchanger 16, where it exchanges heat with another fluid, thereby achieving the system's cooling or heating effect.

[0156] The connection between the gas-liquid separator 8 and the plate heat exchanger 16 ensures stable refrigerant circulation within the system. The separation function of the gas-liquid separator 8 prevents the instability caused by gas-liquid mixing, thus improving the overall system stability. The second solenoid valve 18 allows for precise control of refrigerant flow. This control capability not only facilitates flexible adjustments based on actual needs but also enables timely shut-off of refrigerant flow in case of malfunctions, protecting system safety. As the core component for heat exchange, the plate heat exchanger 16's high-efficiency heat exchange performance contributes to improved overall system energy efficiency. Through its synergistic effect with the gas-liquid separator 8, it ensures that the refrigerant entering the plate heat exchanger 16 is in optimal condition, thereby achieving a highly efficient energy exchange process.

[0157] like Figure 3 As shown, the liquid pipe of the plate heat exchanger 16 is equipped with a second temperature sensor 17, a second electronic expansion valve 19, and a second filter 20.

[0158] In this embodiment of the invention, the second temperature sensor 17 is a temperature sensor that monitors the temperature of the refrigerant in the liquid pipe in real time. The temperature sensor converts the detected temperature signal into an electrical signal and transmits it to the system's control unit. The control unit determines the current temperature state of the refrigerant based on the received temperature signal and adjusts the system's operating parameters accordingly. The second electronic expansion valve 19 is a controllable throttling device that adjusts its opening degree according to the control unit's instructions, thereby controlling the refrigerant flow rate. When the control unit determines that the refrigerant flow rate needs to be adjusted based on the signal from the second temperature sensor 17, it sends a command to the second electronic expansion valve 19 to open or close it accordingly. By precisely controlling the refrigerant flow rate, the system can ensure that the heat exchange process in the plate heat exchanger 16 is efficient and stable. The second filter 20 is used to filter impurities and particulate matter in the refrigerant. The filter contains a filter screen or other filter media, which can effectively intercept and remove contaminants in the refrigerant. The clean refrigerant then flows into the next stage of the system, ensuring the normal operation of subsequent components and extending their service life.

[0159] The real-time monitoring and feedback from the second temperature sensor 17 enables the system to precisely control the refrigerant temperature, ensuring that the plate heat exchanger 16 operates within a suitable temperature range and improving heat exchange efficiency. Through the precise control of the second electronic expansion valve 19, the system can adjust the refrigerant flow rate according to actual needs, avoiding unnecessary energy consumption and achieving energy-efficient operation. The second filter 20 effectively filters impurities and particulate matter in the refrigerant, preventing contaminants from entering subsequent system components, protecting equipment from damage, and extending its service life. The coordinated work of these components improves the stability and reliability of the entire refrigerant system, reduces the possibility of failure, and ensures long-term stable operation of the system.

[0160] like Figure 3As shown, the gas-liquid separator 8 is equipped with a third temperature sensor 21, a compressor 22, and a second maintenance valve 23 on the liquid pipe connected to the gas pipe 9.

[0161] In this embodiment of the invention, the third temperature sensor 21 is installed on the liquid pipe to monitor the temperature of the refrigerant flowing through it in real time. It converts the detected temperature signal into an electrical signal and transmits it to the processor of the control system. The processor determines the current state of the refrigerant based on the received temperature data and adjusts the system's operating parameters accordingly, such as the working pressure of the compressor 22. The compressor 22 is a pressure control device installed on the liquid pipe to regulate the refrigerant pressure. It changes the refrigerant pressure in the liquid pipe through an internal regulating mechanism according to the instructions of the control system. The operating state of the compressor 22 is closely related to the monitoring data of the third temperature sensor 21, ensuring that the refrigerant flows at a suitable pressure and temperature. The second maintenance valve 23 is an automatically controlled valve installed on the liquid pipe for system maintenance and repair. During normal system operation, it remains open, allowing the refrigerant to flow smoothly. When maintenance or repair is required, the valve can be closed to cut off the refrigerant flow in the liquid pipe, thereby safely carrying out the relevant work.

[0162] The combined use of the third temperature sensor 21 and the compressor 22 enables precise control of refrigerant temperature and pressure. This control helps maintain stable system operation, improves energy efficiency, and reduces potential problems caused by temperature and pressure fluctuations. Through the precise adjustment of refrigerant pressure by the compressor 22, the system ensures that the refrigerant flows under optimal conditions, thereby achieving efficient energy transfer. This helps improve the overall cooling or heating efficiency of the system. The second maintenance valve 23 makes system maintenance and repair more convenient. By simply closing the valve, relevant components can be safely inspected, repaired, or replaced, reducing maintenance time and costs and improving system safety. For example, when the third temperature sensor 21 detects an abnormal temperature, the control system can promptly adjust the operating pressure of the compressor 22 to prevent equipment damage or safety accidents. Simultaneously, the second maintenance valve 23 can also quickly cut off refrigerant flow in emergencies, further ensuring system safety.

[0163] It should be noted that this system is a system corresponding to the above method. All implementation methods in the above method embodiments are applicable to this embodiment and can achieve the same technical effect.

[0164] Embodiments of the present invention also provide a computing device, including: a processor and a memory storing a computer program, wherein the computer program, when executed by the processor, performs the method described above. All implementations in the above method embodiments are applicable to this embodiment and can achieve the same technical effects.

[0165] Embodiments of the present invention also provide a computer-readable storage medium storing instructions that, when executed on a computer, cause the computer to perform the method described above. All implementations in the above method embodiments are applicable to this embodiment and can achieve the same technical effects.

[0166] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A control method for improving the reliability of high-temperature refrigerant oil return in a multi-split air conditioner, characterized in that, The application comprises the following steps: When the outdoor environment temperature meets the preset oil return condition, and it is detected that the compressor reduces the frequency due to high pressure or current protection during the last cooling oil return process, the control of the indoor unit and the oil separator circuit in the multi-split system is triggered; According to the starting condition, the indoor unit is controlled differently, and the electronic expansion valve is adjusted according to the indoor temperature and the temperature sensor state to obtain the indoor unit control result, including: detecting whether the outdoor environment temperature, pressure and current parameters reach the preset starting condition threshold; After confirming that the starting condition is met, the current state of each indoor unit is obtained, including the indoor temperature, the set temperature and the temperature sensor state; according to the obtained indoor unit state information, each indoor unit is controlled differently, the indoor unit with the open temperature sensor and the indoor temperature lower than the set temperature is identified as the low-temperature demand unit, and the electronic expansion valve of the low-temperature demand unit is adjusted to the closed or minimum opening state; the indoor unit with the open temperature sensor and the indoor temperature higher than the set temperature is identified as the high-temperature demand unit, and the superheat information of the high-temperature demand unit is obtained; According to the superheat information, the opening of the electronic expansion valve is adjusted; the target range of the superheat is set, and the electronic expansion valve is adjusted by the controller to maintain the superheat in the target range; the adjusted electronic expansion valve control signal is output to the corresponding indoor unit to control the indoor unit; through the output of the control signal, each indoor unit adjusts the refrigerant flow to obtain the corresponding indoor unit control result; According to the indoor unit control result, the outdoor unit is controlled, including the compressor frequency adjustment and the electronic expansion valve adjustment; At the same time of the outdoor unit control, the oil separator circuit is controlled to keep a specific electromagnetic valve in the open state to improve the oil return rate; The oil return process and the environment temperature are continuously monitored, and when the exit condition is met, the normal control mode is automatically restored.

2. The control method for improving the reliability of high-temperature refrigerant oil return of a multi-split system according to claim 1, characterized in that, The target range of the superheat is set, and the electronic expansion valve is adjusted by the controller to maintain the superheat in the target range, including: A superheat target range is set, and the range is an interval of a temperature difference; The indoor temperature and the evaporator outlet temperature of the indoor unit are monitored in real time by the temperature sensor, and the superheat is calculated in real time according to the monitored temperature data; The PID controller is adjusted by presetting the parameters and initializing the PID controller, including the proportional coefficient, the integral coefficient and the differential coefficient; The real-time calculated superheat data is input into the PID controller, and the controller calculates the adjustment amount of the electronic expansion valve according to the set target range and the current superheat data; The adjustment amount is converted into the corresponding control signal and output to the actuator of the electronic expansion valve; The electronic expansion valve adjusts the opening according to the received control signal to adjust the flow of the refrigerant flowing into the evaporator; During the control process, the real-time superheat data is continuously monitored, and if the superheat deviates from the target range, the controller will automatically adjust the opening of the electronic expansion valve to make the superheat return to the target range.

3. The control method for improving the reliability of high-temperature refrigerant oil return of a multi-split air conditioner according to claim 2, characterized in that, The calculation formula of the superheat is: ； wherein, represents a superheat degree; represents an indoor temperature; represents an evaporator outlet temperature; represents a seasonal energy efficiency ratio; represents an index correction coefficient of SEER; represents an evaporator efficiency coefficient; represents a pressure correction coefficient; represents a pressure difference; represents a reference pressure; represents a humidity correction coefficient; represents a relative humidity; represents a reference humidity; represents an index correction coefficient of a humidity difference; represents an air flow rate; represents a reference air flow rate; represents an index correction coefficient of an air flow rate.

4. The control method for improving the reliability of high-temperature refrigerant oil return of a multi-split air conditioner according to claim 3, characterized in that, The calculation formula of the adjustment amount of the electronic expansion valve is: ； where A represents an adjustment amount of the electronic expansion valve; K represents a proportional coefficient; CD represents a difference between a current measured value and a set value; represents a deviation index; represents an amplitude, represents an angular frequency, represents an initial phase; t represents a current time point; represents an integral coefficient; represents a deviation integral; represents an integral variable; e represents a base number of a natural logarithm; represents a decay constant; D represents a differential coefficient; d represents a differential operator; DD represents a deviation differential; represents a differential multiplier.

5. The control method for improving the reliability of high-temperature refrigerant oil return of a multi-split air conditioner according to claim 4, characterized in that, According to the indoor unit control result, the outdoor unit is controlled, including compressor frequency adjustment and electronic expansion valve adjustment, including: According to the indoor unit control result, the current indoor unit cooling capacity demand and operating state are analyzed; According to the indoor unit demand, the load borne by the outdoor unit is calculated; According to the outdoor unit load, the operating frequency of the compressor is adjusted, and according to the indoor unit demand and the operating state of the compressor, the opening degree of the electronic expansion valve is adjusted.

6. The control method for improving the reliability of high-temperature refrigerant oil return of a multi-split air conditioner according to claim 5, characterized in that, The load borne by the outdoor unit is calculated by the following formula: ； wherein, represents an outdoor unit load; n represents the total number of indoor units; i represents an index variable; represents a cooling capacity demand of the i-th indoor unit; represents an efficiency factor of the i-th indoor unit; represents a correction factor; represents an outdoor ambient temperature; represents a current indoor temperature of the i-th indoor unit; represents a temperature reference value; represents an outdoor ambient humidity; represents a humidity reference value; represents an aging degree of the i-th indoor unit; represents a maximum value of a maintenance condition; represents a maintenance condition of the i-th indoor unit.​​​ 7. A control system for improving the reliability of high-temperature refrigeration oil return in a multi-split system, characterized in that, Applied to the method of any one of claims 1 to 6, including: The acquisition module is used to trigger the control of the outdoor unit, the indoor unit and the oil separator circuit in the multi-split system when the outdoor environment temperature meets the preset oil return condition and the compressor is detected to reduce the frequency due to high pressure or current protection in the last cool room oil return process; according to the starting condition, the indoor unit is controlled, the electronic expansion valve is adjusted according to the indoor temperature and the temperature sensor state, and the indoor unit control result is obtained; The processing module is used to control the outdoor unit according to the indoor unit control result, including compressor frequency adjustment and electronic expansion valve adjustment; while controlling the outdoor unit, the oil separator circuit is controlled to keep the specific electromagnetic valve open to improve the oil return rate; the oil return process and the environment temperature are continuously monitored, and when the exit condition is met, the normal control mode is automatically restored.

8. A computing device, comprising: Including: One or more processors; Storage device for storing one or more programs, when the one or more programs are executed by the one or more processors, so that the one or more processors implement the method of any one of claims 1 to 6.

9. A computer-readable storage medium, characterized in that, The computer readable storage medium stores a program which is executed by the processor to implement the method of any one of claims 1 to 6.

Images