An ejector-based and closed-loop controlled air conditioner low-temperature refrigeration oil return system and method

Abstract

The application relates to the air conditioning refrigeration technical field, and discloses an air conditioner low-temperature refrigeration oil return system and method based on injection and closed-loop control. The system comprises a real-time parameter acquisition module, an injector pressure difference calculation module, an oil return threshold judgment module, an adjusting valve opening degree calculation module, a lubricating oil injection module and an injector stop control module. First, the compressor discharge and suction gas pressure of an air conditioning device, the real-time oil level of an oil separator and the outlet superheat of an evaporator are acquired in real time; then, the compressor injector pressure difference is calculated; the oil return starting condition threshold is judged based on the oil level and the superheat; after the condition is met, the injector adjusting valve target opening degree is calculated in combination with the pressure difference and the preset oil level target value; the oil separator bottom lubricating oil is injected into the compressor according to the opening degree; and finally, the injector is stopped according to the real-time oil level. The application can improve the control and execution efficiency of the air conditioner low-temperature refrigeration oil return.

Description

Technical Field

[0001] This invention relates to the field of air conditioning and refrigeration technology, and in particular to an air conditioning low-temperature refrigeration oil return system and method based on ejector and closed-loop control. Background Technology

[0002] In low-temperature cooling operation scenarios of air conditioning, existing oil return technologies mostly adopt open-loop control, which lacks real-time acquisition and dynamic adjustment of air conditioning equipment operating parameters. It cannot adapt the oil return strategy according to real-time changes in compressor discharge and suction pressure, oil level in oil separator, and evaporator outlet superheat. This can easily lead to problems such as unreasonable oil return start timing and fixed valve opening, resulting in low lubricating oil ejection efficiency and difficulty in quickly returning the lubricating oil in the oil separator to the compressor, thus affecting the refrigeration cycle efficiency of the air conditioning equipment.

[0003] Meanwhile, traditional air conditioning oil return systems lack a comprehensive mechanism for calculating pressure difference and determining oil level thresholds. Monitoring oil return stop conditions involves only simple threshold judgments without continuous monitoring and verification processes. This can easily lead to insufficient or excessive oil return, which not only reduces the compressor's lubrication effect and increases the risk of equipment wear, but also results in poor operational stability of air conditioning equipment under low-temperature conditions due to insufficient oil return control accuracy. Consequently, it fails to meet the high-efficiency oil return requirements in low-temperature cooling scenarios. Therefore, improving the accuracy and efficiency of oil return control under low-temperature cooling conditions has become an urgent problem to be solved. Summary of the Invention

[0004] This invention provides an air conditioning low-temperature refrigeration oil return system and method based on ejection and closed-loop control to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, this invention provides a low-temperature refrigeration oil return system for air conditioning based on ejector and closed-loop control. The system comprises a real-time parameter acquisition module, an ejector pressure difference calculation module, an oil return threshold determination module, a regulating valve opening calculation module, a lubricating oil ejection module, and an ejector stop control module, wherein: The real-time parameter acquisition module is used to acquire real-time parameters of the air conditioning equipment, and obtain the operating parameters of the air conditioning equipment, such as compressor discharge pressure, compressor suction pressure, real-time oil level in the oil separator, and evaporator outlet superheat. The ejector pressure differential module is used to perform pressure differential analysis on the compressor's discharge pressure and suction pressure to obtain the compressor's ejector pressure differential. The oil return threshold determination module is used to determine the threshold of the oil return start-up conditions of the ejector based on the real-time oil level height and the evaporator outlet superheat, and obtain a determination result that meets the oil return start-up conditions. The valve opening calculation module is used to control and calculate the opening of the ejector's regulating valve based on the pressure difference and the preset oil level target value when the return oil start condition is met, so as to obtain the target opening of the ejector. The lubricating oil ejector module is used to power eject the lubricating oil at the bottom of the oil separator based on the target opening, so as to obtain the lubricating oil ejected back to the compressor. The ejector stop control module is used to control the operation of the ejector based on the real-time oil level, thereby obtaining the stop state of the ejector.

[0006] In a preferred embodiment, when the real-time parameter acquisition module performs real-time parameter acquisition of the air conditioning equipment to obtain the compressor discharge pressure, compressor suction pressure, real-time oil level in the oil separator, and evaporator outlet superheat of the air conditioning equipment, it is specifically used for: Based on the exhaust pressure transmitter of the air conditioning equipment compressor, the pressure of the refrigerant gas flow discharged by the compressor is detected in real time to obtain the exhaust pressure electrical signal of the compressor. Based on the suction pressure transmitter on the compressor suction line, the pressure of the refrigerant flow back to the compressor is detected in real time to obtain the suction pressure electrical signal of the compressor. The oil level in the oil separator is detected in real time to obtain an electrical signal of the real-time oil level. The superheat of the refrigerant at the evaporator outlet is directly detected to obtain an electrical signal indicating the superheat at the evaporator outlet.

[0007] In a preferred embodiment, when the ejector pressure differential module performs pressure differential analysis on the compressor's discharge pressure and intake pressure to obtain the compressor's ejector pressure differential, it specifically performs the following functions: The compressor discharge pressure is used as the high-pressure input signal, and the compressor suction pressure is used as the low-pressure input signal, which are connected to the positive and negative input terminals of the compressor pressure comparator. The initial pressure difference signal of the compressor is obtained by performing a real-time subtraction operation on the high-pressure input signal and the low-pressure input signal. The initial pressure difference signal is filtered and amplified to obtain the conditioned pressure difference signal of the compressor. Zero-point calibration compensation is performed on the conditioned differential pressure signal to obtain the ejector pressure difference of the compressor.

[0008] In a preferred embodiment, when the oil return threshold determination module performs a threshold determination on the oil return start-up conditions of the ejector based on the real-time oil level and evaporator outlet superheat, and obtains a determination result that satisfies the oil return start-up conditions, it is specifically used for: Obtain the preset oil level determination threshold and the preset superheat determination threshold; The real-time oil level is compared with a preset oil level judgment threshold to obtain the comparison result of the real-time oil level. The superheat at the evaporator outlet is compared with the superheat determination threshold to obtain the comparison result of the superheat at the evaporator outlet. Based on the comparison results of the real-time oil level and the evaporator outlet superheat, it is confirmed that the oil return start-up conditions are met.

[0009] In a preferred embodiment, when the oil return threshold determination module performs a comparison based on the real-time oil level height and the evaporator outlet superheat, and confirms that the oil return start-up conditions are met, it is specifically used for: When the real-time oil level is lower than the preset oil level threshold, the current operating frequency of the compressor is obtained; Based on the current operating frequency, a mapping query is performed on the return oil start-up oil level threshold to obtain the return oil start-up oil level threshold for the current operating frequency; The real-time oil level height and the return oil start-up oil level threshold are checked and determined to obtain the check and determination result of the real-time oil level height; When the verification result is that the real-time oil level is lower than the return oil start oil level threshold, the duration of the real-time oil level being lower than the return oil start oil level threshold is recorded and monitored to obtain the oil shortage duration of the real-time oil level. When the duration of oil shortage reaches a preset time threshold, the oil return start condition is confirmed to be met.

[0010] In a preferred embodiment, when the valve opening calculation module performs the function of controlling and calculating the opening of the ejector's regulating valve based on the pressure difference and a preset oil level target value when the return oil start condition is met, to obtain the target opening of the ejector, it is specifically used for: The deviation between the real-time oil level and the preset oil level target value is generated to obtain the oil level deviation signal of the real-time oil level. The equivalent cross-sectional area of ​​the ejector channel and the ejector fluid density of the ejector are obtained by querying the structural parameter library of the ejector. Substituting the ejector pressure difference, the equivalent cross-sectional area of ​​the ejector channel, and the ejector fluid density into the ejector flow rate-pressure difference correlation formula, the basic opening value of the ejector is obtained. The ejector flow rate-pressure difference correlation formula is as follows: ; The ejector pressure difference is denoted as The equivalent cross-sectional area of ​​the ejection channel is denoted as The ejector fluid density is denoted as , The flow coefficient reflects the resistance characteristics of the fluid as it passes through the ejector channel. The opening correction amount is calculated and generated based on the oil level deviation signal, the preset proportional coefficient, and the preset integral coefficient; The target opening of the ejector is obtained by superimposing the base opening value and the opening correction amount.

[0011] In a preferred embodiment, when the valve opening calculation module generates the opening correction amount based on the oil level deviation signal, a preset proportional coefficient, and a preset integral coefficient, it is specifically used for: The instantaneous value of the oil level deviation at the current sampling moment in the oil level deviation signal is sampled instantaneously and denoted as... , where n is the sequence number of the current sampling time; Based on the instantaneous value of the oil level deviation at the current sampling time, all the instantaneous values ​​of the oil level deviation are accumulated to generate a cumulative oil level deviation value. ; The proportionality coefficient is denoted as The integral coefficient is denoted as The sampling period is denoted as Substituting the above parameters into the following formula for calculating the opening correction, we obtain the opening correction amount, which is as follows:

[0012] in, This is the opening correction amount at the current sampling time.

[0013] In a preferred embodiment, when the lubricating oil ejector module performs the function of dynamically ejecting the lubricating oil at the bottom of the oil separator based on the target opening degree, to obtain lubricating oil ejected back to the compressor, it is specifically used for: Based on the target opening, the opening of the electronic expansion valve of the ejector is adjusted to obtain the target valve opening. Based on the high-pressure fluid on / off valve of the ejector, the high-pressure refrigerant discharged from the compressor enters the ejector, and the nozzle of the ejector is accelerated and depressurized to obtain a low-pressure zone in the ejector suction chamber that is lower than the internal pressure of the oil separator; Based on the pressure difference between the low-pressure zone and the inside of the oil separator, the liquid lubricating oil deposited at the bottom of the oil separator is drawn and drained to obtain the lubricating oil in the ejector suction chamber. The lubricating oil and the high-pressure refrigerant are homogenized to obtain a two-phase fluid for the ejector. The two-phase fluid is pressure-transmitted to obtain lubricating oil that is injected back into the compressor.

[0014] In a preferred embodiment, when the ejector stop control module performs the function of stopping the ejector based on the real-time oil level to obtain the ejector's stop state, it specifically performs the following functions: The real-time oil level in the oil separator is monitored in real time to obtain the current monitoring value of the real-time oil level. The current monitoring value is compared with the preset stop oil level. When the current monitoring value reaches the preset stop oil level, a stop trigger command for the ejector is obtained. Based on the stop trigger command of the ejector, the on / off valve at the front end of the high-pressure fluid inlet of the ejector is closed to obtain the fully closed state of the on / off valve; Based on the fully closed state of the on / off valve, the inflow of high-pressure refrigerant discharged from the compressor is blocked, resulting in a stop state where the ejector stops ejecting.

[0015] To address the aforementioned problems, this invention also provides a method for low-temperature refrigeration oil return in air conditioning based on ejection and closed-loop control, the method comprising: Ⅰ. Used for real-time parameter acquisition of air conditioning equipment, to obtain the operating parameters of the air conditioning equipment such as compressor discharge pressure, compressor suction pressure, real-time oil level in the oil separator, and evaporator outlet superheat. II. Used to perform pressure differential analysis on the discharge pressure and suction pressure of the compressor to obtain the ejector pressure differential of the compressor; III. Used to determine the threshold of the oil return start-up conditions of the ejector based on the real-time oil level and evaporator outlet superheat, and obtain the determination result that meets the oil return start-up conditions; IV. When the oil return start-up conditions are met, the opening degree of the regulating valve of the ejector is controlled and calculated based on the pressure difference and the preset oil level target value to obtain the target opening degree of the ejector; V. Used to power eject the lubricating oil at the bottom of the oil separator based on the target opening degree, so as to obtain the lubricating oil ejected back to the compressor; VI. Used to control the operation of the ejector based on the real-time oil level, thereby obtaining the stop state of the ejector.

[0016] Compared with the prior art, the present invention has the following beneficial effects: 1. The air conditioning low-temperature refrigeration oil return system of this invention achieves real-time acquisition of air conditioning operating parameters and dynamic oil return control through multi-module collaborative closed-loop control logic. Relying on precise pressure difference calculation, multi-dimensional oil return threshold determination, and scientific adjustment valve opening calculation, the system ensures that the start-up timing of the ejector oil return, the adjustment valve opening, and the actual operating conditions of the air conditioner are highly compatible, significantly improving the efficiency of lubricating oil ejection. This allows for rapid return of lubricating oil from the oil separator to the compressor, effectively ensuring the efficient operation of the air conditioning equipment's refrigeration cycle. Simultaneously, the system continuously monitors and verifies the oil level, combining this with a preset stop oil level to achieve precise start-stop control of the ejector's working state. This significantly improves the control accuracy of the oil return process, accurately controlling the amount of oil returned, avoiding oil return-related problems, and continuously maintaining good lubrication of the compressor.

[0017] 2. This invention achieves precise detection and processing of operating parameters through specialized sensors and computational logic, providing reliable data support for oil return control. Relying on the ejector flow-pressure differential correlation and proportional-integral algorithm, it accurately calculates the target opening of the regulating valve, making the lubricating oil ejection process more scientific and rational. The system deeply integrates ejection technology with closed-loop control, forming an efficient linkage response mechanism between modules. It can dynamically adjust the oil return strategy according to the real-time operating status of the air conditioning equipment, significantly improving the operational stability of the air conditioning equipment under low-temperature refrigeration conditions, while reducing the risk of equipment wear, extending the service life of the air conditioning equipment, and fully meeting the high-efficiency oil return requirements in low-temperature refrigeration scenarios. Attached Figure Description

[0018] Figure 1 This is a system architecture diagram of an air conditioning low-temperature refrigeration oil return system based on ejector and closed-loop control, provided in an embodiment of the present invention. Figure 2 This is a schematic flowchart of an air conditioning low-temperature refrigeration oil return method based on ejection and closed-loop control, provided in an embodiment of the present invention.

[0019] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments belong to some, but not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] The terminology used in the embodiments of this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention. The singular forms “said” and “the” as used in the embodiments of this invention and the appended claims are also intended to include the plural forms, and “multiple” generally includes at least two unless the context clearly indicates otherwise.

[0022] Depending on the context, the word "if" or "if" as used here can be interpreted as "when," "when," "in response to determination," or "in response to detection." Similarly, depending on the context, the phrase "if determination" or "if detection (of the stated condition or event)" can be interpreted as "when determination," "in response to determination," "when detection (of the stated condition or event)," or "in response to detection (of the stated condition or event)."

[0023] Furthermore, the timing of the steps in the following method embodiments is merely an example and not a strict limitation.

[0024] In practice, the server-side equipment deployed in the air conditioning low-temperature refrigeration oil return system based on ejector and closed-loop control may consist of one or more devices. The aforementioned air conditioning low-temperature refrigeration oil return system based on ejector and closed-loop control can be implemented as: a business instance, a virtual machine, or hardware devices. For example, this air conditioning low-temperature refrigeration oil return system based on ejector and closed-loop control can be implemented as a business instance deployed on one or more devices in a cloud node. Simply put, this air conditioning low-temperature refrigeration oil return system based on ejector and closed-loop control can be understood as software deployed on a cloud node, used to provide the air conditioning low-temperature refrigeration oil return system based on ejector and closed-loop control to various user terminals. Alternatively, this air conditioning low-temperature refrigeration oil return system based on ejector and closed-loop control can also be implemented as a virtual machine deployed on one or more devices in a cloud node. This virtual machine contains application software for managing various user terminals. Alternatively, this air conditioning low-temperature refrigeration oil return system based on ejector and closed-loop control can also be implemented as a server composed of numerous identical or different types of hardware devices, with one or more hardware devices configured to provide the air conditioning low-temperature refrigeration oil return system based on ejector and closed-loop control to various user terminals.

[0025] In terms of implementation, the air conditioning low-temperature refrigeration oil return system based on ejector and closed-loop control and the user terminal are mutually compatible. That is, if the air conditioning low-temperature refrigeration oil return system based on ejector and closed-loop control is implemented as an application installed on a cloud service platform, then the user terminal is a client that establishes a communication connection with the application; or if the air conditioning low-temperature refrigeration oil return system based on ejector and closed-loop control is implemented as a website, then the user terminal is implemented as a webpage; or if the air conditioning low-temperature refrigeration oil return system based on ejector and closed-loop control is implemented as a cloud service platform, then the user terminal is implemented as a mini-program in an instant messaging application.

[0026] like Figure 1 The figure shown is a system architecture diagram of an air conditioning low-temperature refrigeration oil return system based on ejector and closed-loop control provided in an embodiment of the present invention.

[0027] The air conditioning low-temperature refrigeration oil return system 100 based on ejector and closed-loop control described in this invention can be installed on a cloud server. In terms of implementation, it can be used as one or more service devices, or as an application installed on the cloud (e.g., a mobile service operator's server, server cluster, etc.), or it can be developed into a website. Depending on the functions implemented, the air conditioning low-temperature refrigeration oil return system 100 based on ejector and closed-loop control may include a real-time parameter acquisition module 101, an ejector pressure difference calculation module 102, an oil return threshold determination module 103, a regulating valve opening calculation module 104, a lubricating oil ejection module 105, and an ejector stop control module 106. The module described in this invention can also be called a unit, which refers to a series of computer program segments that can be executed by an electronic device processor and can perform a fixed function, stored in the electronic device's memory.

[0028] In this embodiment of the invention, in the air conditioning low-temperature refrigeration oil return system based on ejector and closed-loop control, each of the above modules can be implemented independently and called upon other modules. This calling can be understood as a module connecting to multiple modules of another type and providing corresponding services to those connected modules. In the air conditioning low-temperature refrigeration oil return system based on ejector and closed-loop control provided by this embodiment of the invention, the applicable scope of the air conditioning low-temperature refrigeration oil return system architecture can be adjusted by adding modules and directly calling them without modifying the program code, achieving cluster-style horizontal expansion to quickly and flexibly expand the air conditioning low-temperature refrigeration oil return system based on ejector and closed-loop control. In practical applications, the above modules can be set in the same device or different devices, or they can be set in a virtual device, such as a service instance in a cloud server.

[0029] The following describes, with reference to specific embodiments, each component and its specific workflow of an air conditioning low-temperature refrigeration oil return system based on ejector and closed-loop control: The real-time parameter acquisition module 101 is used to acquire real-time parameters of the air conditioning equipment to obtain the operating parameters of the air conditioning equipment, such as the compressor discharge pressure, compressor suction pressure, real-time oil level in the oil separator, and evaporator outlet superheat. When the real-time parameter acquisition module performs real-time parameter acquisition on the air conditioning equipment to obtain the compressor discharge pressure, compressor suction pressure, real-time oil level in the oil separator, and evaporator outlet superheat, it is specifically used for: Based on the exhaust pressure transmitter of the air conditioning equipment compressor, the pressure of the refrigerant gas flow discharged by the compressor is detected in real time to obtain the exhaust pressure electrical signal of the compressor. Based on the suction pressure transmitter on the compressor suction line, the pressure of the refrigerant flow back to the compressor is detected in real time to obtain the suction pressure electrical signal of the compressor. The oil level in the oil separator is detected in real time to obtain an electrical signal of the real-time oil level. The superheat of the refrigerant at the evaporator outlet is directly detected to obtain an electrical signal indicating the superheat at the evaporator outlet.

[0030] The exhaust pressure transmitter installed at the compressor of the air conditioning equipment forms a connected detection structure with the pipeline through which the refrigerant gas flow from the compressor flows. The exhaust pressure transmitter is in direct contact with the refrigerant gas flow discharged from the compressor. During the operation of the air conditioning equipment, it continuously senses the pressure applied to the refrigerant gas flow and converts the sensed pressure physical quantity into a corresponding electrical signal for output, forming the compressor's exhaust pressure electrical signal.

[0031] The suction pressure transmitter installed on the suction line of the air conditioning equipment compressor forms a closed detection environment with the internal space of the suction line. The suction pressure transmitter is in direct contact with the refrigerant gas flow returning from the compressor. During the operation of the air conditioning equipment, it continuously senses the pressure applied to the refrigerant gas flow and converts the sensed pressure physical quantity into the corresponding electrical signal output, forming the compressor suction pressure electrical signal.

[0032] The capacitive oil level sensor installed inside the oil separator of the air conditioning equipment is in direct contact with the lubricating oil inside the oil separator. The capacitive oil level sensor changes its own capacitance parameter according to the change in the lubricating oil level. The capacitive oil level sensor converts the change in capacitance parameter corresponding to the change in the liquid level into a corresponding electrical signal output, forming a real-time oil level electrical signal inside the oil separator.

[0033] A superheat transmitter installed at the evaporator of the air conditioning equipment forms a fixed detection position with the refrigerant flow position at the evaporator outlet. The superheat transmitter directly senses the temperature and pressure-related physical quantities of the refrigerant at the evaporator outlet synchronously. The superheat transmitter converts the sensed physical quantities into corresponding electrical signals and outputs them to form the superheat electrical signal at the evaporator outlet.

[0034] Beneficial Effects: This preferred implementation method utilizes dedicated sensing and detection equipment to collect key operating parameters of the air conditioning equipment in real time. It relies on exhaust and suction pressure transmitters to accurately capture the refrigerant discharge and return airflow pressures of the compressor and convert them into electrical signals. A capacitive oil level sensor monitors the lubricating oil level in the oil separator in real time, and a superheat transmitter directly detects the refrigerant superheat at the evaporator outlet. All these measures simultaneously output corresponding electrical signals, achieving accurate and real-time acquisition of multi-dimensional parameters. The data acquisition process aligns with the parameter monitoring requirements of low-temperature refrigeration oil return in air conditioning systems. Each detection device is precisely matched to its corresponding monitoring point, converting physical parameters into standardized electrical signals. This provides accurate and continuous basic data support for subsequent modules such as ejector pressure difference calculation, oil return threshold determination, and regulating valve opening estimation. It avoids deviations in oil return control strategy adaptation caused by inaccurate or untimely parameter acquisition, ensuring the accuracy of calculations and decisions in subsequent closed-loop control stages. Simultaneously, it improves the efficiency and reliability of parameter acquisition, laying a data foundation for accurate closed-loop control of the low-temperature refrigeration oil return system in air conditioning systems.

[0035] The ejector pressure differential module 102 is used to perform pressure differential analysis on the compressor discharge pressure and suction pressure to obtain the ejector pressure differential of the compressor. When the ejector pressure differential module performs pressure differential analysis on the compressor's discharge pressure and suction pressure to obtain the compressor's ejector pressure differential, it is specifically used for: The compressor discharge pressure is used as the high-pressure input signal, and the compressor suction pressure is used as the low-pressure input signal, which are connected to the positive and negative input terminals of the compressor pressure comparator. The initial pressure difference signal of the compressor is obtained by performing a real-time subtraction operation on the high-pressure input signal and the low-pressure input signal. The initial pressure difference signal is filtered and amplified to obtain the conditioned pressure difference signal of the compressor. Zero-point calibration compensation is performed on the conditioned differential pressure signal to obtain the ejector pressure difference of the compressor.

[0036] The compressor discharge pressure signal acquired by the real-time parameter acquisition module is used as the high-pressure input signal and connected to the positive input terminal of the compressor pressure comparator. The compressor suction pressure signal is used as the low-pressure input signal and connected to the inverted input terminal of the compressor pressure comparator. This allows the two pressure signals to form a corresponding input signal connection state within the pressure comparator, providing a matching signal input basis for subsequent pressure difference calculation.

[0037] The compressor pressure comparator's built-in arithmetic unit performs real-time numerical subtraction on the high-pressure input signal connected to the positive input terminal and the low-pressure input signal connected to the negative input terminal. The subtraction process always follows the real-time changes of the two input signals synchronously, and finally outputs an initial pressure difference signal of the compressor in the form of an electrical signal that reflects the pressure difference between the two.

[0038] The initial pressure difference signal is filtered by a low-pass filter circuit with a preset filtering frequency of 20Hz to remove high-frequency interference components mixed in the signal. Then, the filtered signal is linearly amplified by a signal amplification circuit according to a fixed amplification factor so that the signal strength reaches the standard threshold range for subsequent signal processing, and finally the conditioned pressure difference signal of the compressor is obtained.

[0039] The conditioned differential pressure signal is connected to the zero-point calibration compensation circuit. The standard zero value of the pressure difference when the air conditioning equipment compressor is without operating load is used as the calibration benchmark. The signal amplitude of the conditioned differential pressure signal is compensated and corrected to eliminate the signal zero-point offset problem caused by the error of the circuit components themselves. This allows the corrected signal to accurately correspond to the actual pressure difference value, and finally obtains the ejector pressure difference of the compressor.

[0040] Beneficial Effects: This implementation method achieves accurate calculation of the compressor's exhaust and intake pressure difference through standardized signal access and multi-level processing, providing core pressure parameter support for ejector oil return. The exhaust and intake pressures are respectively used as high and low pressure signals input to the corresponding input terminals of the comparator, ensuring the matching and relevance of signal calculations. Real-time subtraction directly reflects the pressure difference, and the output initial pressure difference signal closely matches the real-time operating status of the system. Filtering and amplification processes remove signal interference and enhance signal strength, ensuring the pressure difference signal meets the processing standards of subsequent modules and preventing noise from affecting calculation accuracy. Zero-point calibration compensation is then performed using the system reference value to eliminate signal offset caused by inherent errors in circuit components, ultimately obtaining a precise ejector pressure difference. The entire process optimizes signal quality layer by layer, ensuring the real-time performance, accuracy, and stability of the pressure difference value, providing reliable basic data for subsequent regulating valve opening calculations, preventing ejector opening control inaccuracies due to pressure difference parameter deviations, and improving the accuracy of closed-loop control in the air conditioning low-temperature refrigeration oil return system.

[0041] The oil return threshold determination module 103 is used to determine the oil return start-up conditions of the ejector based on the real-time oil level height and the evaporator outlet superheat, and obtain a determination result that meets the oil return start-up conditions. When the oil return threshold determination module performs a threshold determination on the oil return start-up conditions of the ejector based on the real-time oil level and evaporator outlet superheat, and obtains a determination result that satisfies the oil return start-up conditions, it is specifically used for: Obtain the preset oil level determination threshold and the preset superheat determination threshold; The real-time oil level is compared with a preset oil level judgment threshold to obtain the comparison result of the real-time oil level. The superheat at the evaporator outlet is compared with the superheat determination threshold to obtain the comparison result of the superheat at the evaporator outlet. Based on the comparison results of the real-time oil level and the evaporator outlet superheat, it is confirmed that the oil return start-up conditions are met.

[0042] The preset oil level judgment threshold and superheat judgment threshold are retrieved from the preset parameter storage unit of the oil return threshold judgment module. The oil level judgment threshold is the minimum liquid level reference value of the oil separator lubricating oil required for stable operation of the compressor under low temperature refrigeration conditions of the air conditioning equipment. The superheat judgment threshold is the superheat reference value of the refrigerant at the evaporator outlet to maintain normal refrigeration cycle. The standard values ​​of the two judgment thresholds are directly obtained as the reference basis for threshold judgment.

[0043] The real-time oil level height in the oil separator, transmitted by the real-time parameter acquisition module, is directly compared with the preset oil level judgment threshold. The comparison process is based solely on the actual detected oil level height and the threshold standard value, without any other correction or adjustment steps. The comparison result of the real-time oil level height, reflecting the comparison relationship between the two values, is directly output.

[0044] The detected value of superheat at the evaporator outlet transmitted by the real-time parameter acquisition module is compared with the preset superheat judgment threshold. The judgment process is based solely on the actual detected value of superheat and the threshold standard value. It only determines whether the detected value reaches the threshold standard and directly outputs the comparison result of the superheat at the evaporator outlet, which reflects the relationship between the two values.

[0045] The comparison results of real-time oil level height and evaporator outlet superheat are synchronously input into the logic judgment unit of the oil return threshold judgment module. This unit uses the preset logic of air conditioning low-temperature cooling oil return as the judgment basis. When both comparison results meet the basic logic conditions for oil return start, it directly outputs the judgment result confirming that the oil return start conditions are met.

[0046] Beneficial Effects: This implementation method provides a precise and scientific triggering basis for ejector oil return start-up through a standardized process of dual-parameter threshold determination, avoiding the problem of unreasonable oil return start-up timing. It retrieves oil level and superheat determination thresholds adapted to the low-temperature cooling conditions of air conditioning from a preset parameter unit, providing a unified and reproducible benchmark for determination and ensuring consistency of determination standards. Targeted threshold comparisons and threshold judgments are performed on real-time oil level height and evaporator outlet superheat, directly outputting intuitive comparison results that accurately reflect the actual state of the system's core operating parameters. Based on the dual-parameter comparison results, a comprehensive logical determination is performed, combining the two key indicators of oil level and superheat as the basis for oil return start-up determination, aligning with the actual operating conditions of low-temperature cooling oil return in air conditioning and avoiding the one-sidedness of single-parameter determination. The entire determination process is clear and standardized, enabling rapid and accurate identification of whether the system meets the oil return start-up conditions, providing reliable determination results for subsequent closed-loop control, improving the accuracy of oil return start-up triggering, and ensuring the adaptability of the oil return strategy under low-temperature cooling conditions for air conditioning equipment.

[0047] When the oil return threshold determination module performs a comparison based on the real-time oil level and the evaporator outlet superheat, and confirms that the oil return start-up conditions are met, it is specifically used for: When the real-time oil level is lower than the preset oil level threshold, the current operating frequency of the compressor is obtained; Based on the current operating frequency, a mapping query is performed on the return oil start-up oil level threshold to obtain the return oil start-up oil level threshold for the current operating frequency; The real-time oil level height and the return oil start-up oil level threshold are checked and determined to obtain the check and determination result of the real-time oil level height; When the verification result is that the real-time oil level is lower than the return oil start oil level threshold, the duration of the real-time oil level being lower than the return oil start oil level threshold is recorded and monitored to obtain the oil shortage duration of the real-time oil level. When the duration of oil shortage reaches a preset time threshold, the oil return start condition is confirmed to be met.

[0048] If the real-time oil level comparison result shows that the value is lower than the preset oil level judgment threshold, the current operating frequency value of the compressor is retrieved from the compressor operation monitoring unit of the air conditioning equipment. This value is the actual Hertz number of the compressor currently operating and is directly used as the basic reference data for subsequent threshold mapping queries.

[0049] The obtained compressor current operating frequency value is used as the search keyword, and a precise matching query is performed in the frequency-oil level threshold mapping database built into the oil return threshold determination module. This database pre-stores the standard values ​​of the oil return start-up oil level threshold corresponding to the full operating frequency range of the air conditioning equipment. Based on the search results, the corresponding standard values ​​are directly extracted to obtain the oil return start-up oil level threshold for the current operating frequency.

[0050] The real-time oil level height detection value inside the oil separator transmitted by the real-time parameter acquisition module is directly compared with the oil level threshold for the current operating frequency. The comparison process has no additional correction steps, and the real-time oil level height verification result reflecting the comparison relationship between the two values ​​is directly output based solely on the actual detection value and the threshold standard value.

[0051] When the real-time oil level verification result shows that the value is lower than the return oil start oil level threshold of the current operating frequency, the timing unit built into the return oil threshold judgment module is activated. This unit uses the system preset 1 second as the minimum timing unit to continuously record the time and monitor the state of the real-time oil level being lower than the return oil start oil level threshold until the state changes or the preset time threshold is reached, and directly obtains the oil shortage duration of the real-time oil level.

[0052] The oil shortage duration recorded by the monitoring is compared with the preset time threshold stored in the oil return threshold determination module. The preset time threshold is the shortest duration standard for determining the risk of oil shortage in the compressor under low temperature cooling conditions of air conditioning equipment. When the value of the oil shortage duration reaches the standard value of the preset time threshold, the determination result confirming that the oil return start condition is met is directly output.

[0053] Beneficial Effects: This implementation method adds a multi-level verification and continuous monitoring process to the basic dual-parameter judgment, significantly improving the accuracy and rationality of the oil return start condition judgment and avoiding false or delayed triggering. By combining the compressor's current operating frequency with a dedicated oil return start oil level threshold, the oil level judgment standard is adapted to different compressor operating conditions, conforming to the actual operating needs of low-temperature air conditioning, and abandoning the one-sidedness of fixed thresholds. A secondary verification judgment is performed on the real-time oil level height to further verify the authenticity of the low oil level and reduce the impact of single detection errors. By monitoring the duration of the low oil level and confirming the start only when the preset time threshold is reached, invalid oil return operations caused by short-term oil level fluctuations are effectively avoided. The entire process forms a multi-dimensional and multi-level judgment mechanism, which not only ensures accurate identification of the compressor's true oil shortage state but also avoids unnecessary oil return actions, improving the reliability of oil return start triggering, laying the foundation for subsequent accurate oil return injection, and ensuring the stability of the low-temperature air conditioning system.

[0054] The valve opening calculation module 104 is used to control and calculate the opening of the ejector's regulating valve based on the pressure difference and the preset oil level target value when the return oil start condition is met, so as to obtain the target opening of the ejector. When the valve opening calculation module performs the function of controlling and calculating the opening of the ejector's regulating valve based on the pressure difference and a preset oil level target value when the return oil start condition is met, to obtain the target opening of the ejector, it is specifically used for: The deviation between the real-time oil level and the preset oil level target value is generated to obtain the oil level deviation signal of the real-time oil level. The equivalent cross-sectional area of ​​the ejector channel and the ejector fluid density of the ejector are obtained by querying the structural parameter library of the ejector. Substituting the ejector pressure difference, the equivalent cross-sectional area of ​​the ejector channel, and the ejector fluid density into the ejector flow rate-pressure difference correlation formula, the basic opening value of the ejector is obtained. The ejector flow rate-pressure difference correlation formula is as follows: ; The ejector pressure difference is denoted as The equivalent cross-sectional area of ​​the ejection channel is denoted as The ejector fluid density is denoted as , The flow coefficient reflects the resistance characteristics of the fluid as it passes through the ejector channel. The opening correction amount is calculated based on the oil level deviation signal, the preset proportional coefficient, and the preset integral coefficient.

[0055] The target opening of the ejector is obtained by superimposing the base opening value and the opening correction amount. The real-time oil level height detection value in the oil separator transmitted by the real-time parameter acquisition module is compared with the preset oil level target value adapted to the low-temperature cooling condition of the air conditioner in the valve opening calculation module. The numerical difference is calculated by the signal conversion unit built into the module, which converts the numerical difference into an electrical signal that is linearly related to the magnitude of the difference. This electrical signal can be directly recognized and processed by the subsequent calculation unit to finally obtain the oil level deviation signal of the real-time oil level height.

[0056] The parameter retrieval unit of the valve opening calculation module performs a precise matching query on the ejector structure parameter library built into the module. This parameter library pre-stores the fixed structural parameters of the corresponding ejector model, and all parameters have been calibrated to be consistent with the actual equipment. The retrieval process is based on the unique model identifier of the ejector, without any additional parameter screening steps, and directly extracts the equivalent cross-sectional area of ​​the ejector channel and the ejector fluid density.

[0057] The ejector pressure difference output by the ejector pressure difference calculation module, the retrieved equivalent cross-sectional area of ​​the ejector channel, and the ejector fluid density are simultaneously input to the calculation unit of the valve opening calculation module. The calculation unit performs comprehensive calculation on the three input parameters based on the pre-stored ejector flow rate-pressure difference correlation logic and the ejector channel resistance characteristics reflected by the flow coefficient. The calculation process strictly follows the correlation between flow rate and pressure difference, channel cross-sectional area, and fluid density, and finally obtains the basic opening value of the ejector.

[0058] The generated real-time oil level deviation signal is input to the correction amount generation unit of the valve opening calculation module. This unit retrieves the preset proportional coefficient and preset integral coefficient that are stored in the module and calibrated under operating conditions. It performs comprehensive calculations based on the real-time amplitude and trend of the oil level deviation signal, and converts the calculation results into a numerical quantity that can be directly used for opening adjustment, thus obtaining the opening correction amount.

[0059] The calculated base opening value of the ejector and the generated opening correction value are input into the numerical synthesis unit of the valve opening calculation module. This unit performs a direct linear superposition operation on the two values. The superposition process does not involve any additional parameter correction or numerical adjustment. The superimposed value is the opening control value adapted to the current system operating conditions, and finally the target opening of the ejector is obtained.

[0060] Beneficial Effects: This implementation method achieves accurate calculation of the target opening of the ejector regulating valve through multi-dimensional parameter fusion and step-by-step calculation, providing an adaptable opening control basis for return oil ejection and avoiding the problem of low ejection efficiency caused by a fixed opening. By generating an oil level deviation signal, the difference between the actual oil level and the target value is accurately captured, providing a direct basis for opening correction and meeting the oil level adjustment requirements of closed-loop control. Fixed parameters are retrieved from the structural parameter library to ensure the accuracy of the parameters calculated for the basic opening. The basic opening value is calculated by combining the ejector flow rate-pressure difference correlation logic, making the opening calculation fit the actual fluid characteristics of the ejector. An opening correction amount is generated based on the oil level deviation signal and preset coefficients to achieve dynamic adjustment of the basic opening, making up for the limitations of relying solely on pressure difference calculation. By superimposing and synthesizing the basic opening value and the correction amount, a target opening that adapts to the current pressure difference and oil level deviation is obtained, making the regulating valve opening highly matched with the real-time operating conditions of the air conditioning equipment. The entire process is progressive, organically combining differential pressure, oil level, and equipment structural parameters to improve the accuracy and adaptability of opening calculation, ensure the rationality of lubricating oil injection flow, and improve the efficiency of low-temperature refrigeration oil return and the accuracy of closed-loop control.

[0061] When the valve opening calculation module generates the opening correction amount based on the oil level deviation signal, a preset proportional coefficient, and a preset integral coefficient, it is specifically used for: The instantaneous value of the oil level deviation at the current sampling moment in the oil level deviation signal is sampled instantaneously and denoted as... , where n is the sequence number of the current sampling time; Based on the instantaneous value of the oil level deviation at the current sampling time, all the instantaneous values ​​of the oil level deviation are accumulated to generate a cumulative oil level deviation value. ; The proportionality coefficient is denoted as The integral coefficient is denoted as The sampling period is denoted as Substituting the above parameters into the following formula for calculating the opening correction, we obtain the opening correction amount, which is as follows: ; in, This is the opening correction amount at the current sampling time.

[0062] The sampling unit built into the valve opening calculation module instantaneously acquires the oil level deviation signal. The sampling unit extracts the oil level deviation signal at the current moment at a preset fixed sampling period. This sampling period is a standard time interval adapted to the rate of change of air conditioning equipment parameters. The extracted value at the current moment is the instantaneous value of the oil level deviation at the current sampling moment and is marked accordingly.

[0063] Based on the instantaneous value of the oil level deviation at the current sampling time, the cumulative calculation unit of the valve opening calculation module continuously accumulates all the instantaneous values ​​of oil level deviation extracted from the first sampling time to the current sampling time. There is no numerical rounding or correction in the accumulation process, and the comprehensive value after accumulation is the cumulative value of oil level deviation.

[0064] The pre-calibrated proportional coefficient and integral coefficient are retrieved from the preset parameter storage unit of the valve opening calculation module. At the same time, the fixed sampling period on which the sampling unit performs the sampling operation is extracted. The proportional coefficient and integral coefficient are standard coefficients adapted to the low temperature cooling oil return condition of the air conditioner. The sampling period is a fixed time interval that has been set. The basic data required for all calculations are extracted and prepared.

[0065] The instantaneous value of the oil level deviation at the current sampling time and the proportional coefficient are numerically processed. Then, the cumulative value of the oil level deviation, the integral coefficient, and the sampling period are jointly numerically processed. The results of the two processing are numerically superimposed, and the final value after superposition is the opening correction amount corresponding to the current sampling time.

[0066] The instantaneous value of the oil level deviation at the current sampling moment is obtained by the sampling unit built into the valve opening estimation module by instantaneously sampling the oil level deviation signal. The proportional coefficient and integral coefficient are retrieved from the preset parameter storage unit of the valve opening estimation module. The cumulative value of the oil level deviation is obtained by the cumulative calculation unit of the valve opening estimation module by continuously accumulating all the instantaneous values ​​of the oil level deviation extracted from the first sampling moment to the current sampling moment. The sampling period is the fixed time interval on which the sampling unit performs the sampling operation, and is directly extracted from the valve opening estimation module.

[0067] This calculation method combines the instantaneous value of the oil level deviation and the cumulative value of the oil level deviation at the current sampling moment. After performing corresponding calculations based on the proportional coefficient and integral coefficient respectively, the values ​​are superimposed to generate the opening correction amount at the current sampling moment. This achieves accurate correction of the basic opening value of the ejector control valve, ensuring that the correction amount not only matches the real-time deviation of the oil level but also takes into account the historical cumulative changes in the oil level deviation. This provides an accurate correction basis for determining the subsequent target opening and ensures a high degree of compatibility between the control valve opening and the real-time oil return conditions of the air conditioning equipment.

[0068] When the instantaneous value of the oil level deviation at the current sampling time increases, the value calculated by the proportional coefficient also increases synchronously, and the opening correction amount will show an increasing trend accordingly. When the instantaneous value of the oil level deviation at the current sampling time decreases, the value calculated by the proportional coefficient also decreases synchronously, and the opening correction amount will show a decreasing trend accordingly.

[0069] When the cumulative value of oil level deviation gradually increases with the increase of sampling time, the value after joint calculation of integral coefficient and sampling period increases synchronously, and the opening correction amount will show an increasing trend. When the cumulative value of oil level deviation no longer increases or even decreases, the value after joint calculation of integral coefficient and sampling period remains stable or decreases synchronously, and the opening correction amount will show a stable or decreasing trend.

[0070] The proportional coefficient and integral coefficient are fixed calibration values. When their values ​​do not change, they will not affect the trend of the opening correction amount. Only when the instantaneous value of the oil level deviation and the cumulative value of the oil level deviation change will they directly drive the opening correction amount to produce a corresponding trend change.

[0071] Beneficial Effects: This implementation method generates opening correction amounts through a refined sampling and calculation process, making the adjustment of the ejector regulating valve opening more closely match the real-time operating conditions of the air conditioning equipment and improving the accuracy of opening estimation. Instantaneous sampling of the oil level deviation signal at a fixed sampling period accurately captures the current oil level deviation state, providing real-time and accurate basic data for correction amount calculation and avoiding errors caused by signal delay. Accumulated calculation of the instantaneous deviation values ​​over the entire sampling period fully preserves the historical trend of oil level deviation changes, overcoming the limitations of a single instantaneous value reflecting operating conditions. Comprehensive calculation is performed by combining pre-calibrated proportional and integral coefficients with a fixed sampling period, combining real-time deviation and accumulated deviation to calculate the correction amount. This achieves dynamic and accurate correction of the basic opening by both quickly responding to the current oil level deviation through the proportional coefficient and eliminating long-term accumulated static oil level error through the integral coefficient. The entire process operation logic is aligned with the closed-loop control requirements. The generated opening correction can accurately match the real-time changes and cumulative deviations of the oil level, making the final target opening more suitable for the oil return requirements, effectively improving the efficiency of ejector oil return, and ensuring the closed-loop control accuracy of the air conditioning low-temperature refrigeration oil return system.

[0072] The lubricating oil ejector module 105 is used to power eject the lubricating oil at the bottom of the oil separator based on the target opening, so as to obtain the lubricating oil ejected back to the compressor. When the lubricating oil ejector module performs the function of dynamically ejecting the lubricating oil at the bottom of the oil separator based on the target opening degree, and obtaining the lubricating oil ejected back to the compressor, it is specifically used for: Based on the target opening, the opening of the electronic expansion valve of the ejector is adjusted to obtain the target valve opening. Based on the high-pressure fluid on / off valve of the ejector, the high-pressure refrigerant discharged from the compressor enters the ejector, and the nozzle of the ejector is accelerated and depressurized to obtain a low-pressure zone in the ejector suction chamber that is lower than the internal pressure of the oil separator; Based on the pressure difference between the low-pressure zone and the inside of the oil separator, the liquid lubricating oil deposited at the bottom of the oil separator is drawn and drained to obtain the lubricating oil in the ejector suction chamber. The lubricating oil and the high-pressure refrigerant are homogenized to obtain a two-phase fluid for the ejector. The two-phase fluid is pressure-transmitted to obtain lubricating oil that is injected back into the compressor.

[0073] The ejector target opening output by the valve opening calculation module is transmitted as an adjustment command to the electronic expansion valve control unit of the ejector. The control unit drives the valve stem of the electronic expansion valve to make a linear displacement according to the command until the actual opening of the valve port is completely matched with the target opening value without any deviation. Finally, the target valve port opening of the target opening is obtained.

[0074] An opening command is sent to the high-pressure fluid on / off valve of the ejector, causing the valve port to open completely, allowing the high-pressure refrigerant discharged from the compressor to enter the ejector without obstruction along the preset pipeline. When the high-pressure refrigerant flows through the nozzle of the ejector, due to the gradually narrowing design of the nozzle's flow cross section, the refrigerant flow velocity increases linearly, and the pressure decreases linearly at the same time, ultimately forming a low-pressure zone in the ejector suction chamber with a pressure value lower than that inside the oil separator.

[0075] The suction force is generated by the pressure difference between the low-pressure area of ​​the ejector's suction chamber and the inside of the oil separator. This suction force is transmitted to the bottom of the oil separator through the connecting pipe between the oil separator and the ejector. This creates a continuous suction flow on the liquid lubricating oil deposited at the bottom of the oil separator, causing the lubricating oil to continuously flow into the ejector's suction chamber through the connecting pipe, ultimately resulting in the lubricating oil in the ejector's suction chamber.

[0076] The lubricating oil entering the ejector suction chamber meets the high-speed flowing high-pressure refrigerant in the mixing section of the ejector. The mixing section has a built-in spiral flow guiding structure, which allows the lubricating oil and high-pressure refrigerant to fully mix under the action of the flow guiding structure, forming a mixed fluid with uniform gas-liquid distribution and no stratification, and finally obtaining the two-phase fluid of the ejector.

[0077] The diffuser section of the ejector decelerates and pressurizes the two-phase fluid formed by the mixture, gradually increasing the pressure of the two-phase fluid to a value that matches the suction pressure of the compressor. Then, the pressurized two-phase fluid is continuously transported into the compressor through the outlet pipe of the ejector. The lubricating oil in the two-phase fluid enters the compressor along with the refrigerant, and finally becomes the lubricating oil ejected back into the compressor.

[0078] Beneficial Effects: This implementation method achieves precise power ejection of lubricating oil through a standardized ejection process, allowing the lubricating oil at the bottom of the oil separator to be efficiently returned to the compressor, adapting to the closed-loop oil return requirements of low-temperature air conditioning. The electronic expansion valve orifice is precisely adjusted according to the target opening degree to ensure that the ejection flow rate matches the system operating conditions, providing a basic opening guarantee for ejection. High-pressure refrigerant is introduced through a high-pressure fluid on / off valve, and accelerated and depressurized through a nozzle to form a stable low-pressure zone. The lubricating oil is naturally drawn in by the pressure difference, requiring no additional power, thus improving the energy efficiency and stability of the ejection process. The lubricating oil and high-pressure refrigerant are homogeneously mixed to form a two-phase fluid, preventing lubricating oil stratification from affecting delivery efficiency and ensuring the continuity of the delivery process. The pressure is increased through the diffuser section to match the pressure of the two-phase fluid to the compressor suction end, achieving stable delivery of lubricating oil and ensuring efficient lubricating oil return. The entire process is tightly integrated, the ejection process is precise and controllable, significantly improving the lubricating oil return efficiency, effectively solving the problem of poor oil return under low-temperature refrigeration conditions, ensuring the compressor lubrication effect, and improving the operational stability and refrigeration cycle efficiency of air conditioning equipment.

[0079] The ejector stop control module 106 is used to stop the working state of the ejector based on the real-time oil level, so as to obtain the stop state of the ejector.

[0080] When the ejector stop control module executes the function of stopping the ejector based on the real-time oil level to obtain the ejector's stop state, it specifically performs the following: The real-time oil level in the oil separator is monitored in real time to obtain the current monitoring value of the real-time oil level. The current monitoring value is compared with the preset stop oil level. When the current monitoring value reaches the preset stop oil level, a stop trigger command for the ejector is obtained. Based on the stop trigger command of the ejector, the on / off valve at the front end of the high-pressure fluid inlet of the ejector is closed to obtain the fully closed state of the on / off valve; Based on the fully closed state of the on / off valve, the inflow of high-pressure refrigerant discharged from the compressor is blocked, resulting in a stop state where the ejector stops ejecting.

[0081] The oil level monitoring unit of the ejector stop control module is connected to the capacitive oil level sensor of the real-time parameter acquisition module to detect the signal. The lubricating oil level height in the oil separator is continuously extracted at a fixed monitoring interval of 1 second. Each extracted level height value is used as valid monitoring data of the oil level status, and finally the current monitoring value of the real-time oil level height is obtained.

[0082] The current monitoring value of the real-time oil level height obtained by the oil level monitoring unit is directly compared with the preset stop oil level that is adapted to the low-temperature cooling condition of the air conditioner. The preset stop oil level is the standard liquid level value of the oil separator lubricating oil required for the stable operation of the compressor. When the current monitoring value is completely consistent with the preset stop oil level value, the module's instruction generation unit outputs a control instruction in the form of an electrical signal, and finally obtains the ejector stop trigger instruction.

[0083] The ejector's stop trigger command is transmitted to the electronic control actuator of the on / off valve at the front end of the ejector's high-pressure fluid inlet. After receiving the command, the actuator drives the valve disc of the on / off valve to close until the valve disc and valve seat are seamlessly fitted, the flow passage of the on / off valve is completely blocked, and no fluid can pass through, finally achieving the fully closed state of the on / off valve.

[0084] By relying on the complete closure of the on / off valve, the preset flow path of the high-pressure refrigerant discharged from the compressor to the ejector is completely blocked, preventing the high-pressure refrigerant from entering the ejector. As the ejector loses its power source of high-pressure refrigerant, it cannot form a low-pressure area, and the action of drawing and drawing lubricating oil is simultaneously terminated. All ejection-related operations of the ejector stop running, and finally the ejector stops its ejection operation.

[0085] Beneficial Effects: This implementation method achieves precise shutdown of the ejector's operating status through real-time oil level monitoring and step-by-step stop control, avoiding excessive oil return from affecting the low-temperature cooling operation of the air conditioning equipment. The oil level in the oil separator is monitored at fixed intervals to accurately obtain the current monitoring value and monitor the oil level recovery status in real time, providing reliable data for stop control. The monitored value is compared with the preset stop oil level, and a stop trigger command is generated only when the oil level reaches the target, ensuring oil return to the standard oil level for stable compressor operation and preventing insufficient or excessive oil return. The high-pressure fluid inlet valve is precisely closed according to the command, achieving seamless valve sealing and ensuring the effectiveness of the shutdown action. By blocking the inflow of high-pressure refrigerant, the ejector's power source is directly cut off, causing the ejector to quickly stop ejection operation, with timely shutdown response. The entire process forms a closed-loop control of oil level monitoring - command triggering - valve closing - ejector stop. The steps are simple and the control is precise, ensuring sufficient lubricating oil return to the compressor and timely termination of ejection, improving the automation and accuracy of the oil return system, and ensuring the operational stability of the air conditioning equipment under low-temperature cooling conditions.

[0086] Reference Figure 2 The diagram shown is a schematic flow chart of an air conditioning low-temperature refrigeration oil return method based on ejector and closed-loop control according to an embodiment of the present invention. In this embodiment, the air conditioning low-temperature refrigeration oil return method based on ejector and closed-loop control includes: Ⅰ. Used for real-time parameter acquisition of air conditioning equipment, to obtain the operating parameters of the air conditioning equipment such as compressor discharge pressure, compressor suction pressure, real-time oil level in the oil separator, and evaporator outlet superheat. II. Used to perform pressure differential analysis on the discharge pressure and suction pressure of the compressor to obtain the ejector pressure differential of the compressor; III. Used to determine the threshold of the oil return start-up conditions of the ejector based on the real-time oil level and evaporator outlet superheat, and obtain the determination result that meets the oil return start-up conditions; IV. When the oil return start-up conditions are met, the opening degree of the regulating valve of the ejector is controlled and calculated based on the pressure difference and the preset oil level target value to obtain the target opening degree of the ejector; V. Used to power eject the lubricating oil at the bottom of the oil separator based on the target opening degree, so as to obtain the lubricating oil ejected back to the compressor; VI. Used to control the operation of the ejector based on the real-time oil level, thereby obtaining the stop state of the ejector.

[0087] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention.

[0088] The embodiments of this application can acquire and process relevant data based on artificial intelligence technology. Artificial intelligence is the theory, method, technology, and application system that uses digital computers or machines controlled by digital computers to simulate, extend, and expand human intelligence, perceive the environment, acquire knowledge, and use that knowledge to obtain optimal results.

[0089] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A cryogenic refrigeration oil return system for air conditioning based on ejection and control, characterized in that, The system includes a real-time parameter acquisition module, an ejector pressure difference calculation module, a return oil threshold determination module, a regulating valve opening calculation module, a lubricating oil ejection module, and an ejector stop control module, wherein: The real-time parameter acquisition module is used to acquire real-time parameters of the air conditioning equipment, and obtain the operating parameters of the air conditioning equipment, such as compressor discharge pressure, compressor suction pressure, real-time oil level in the oil separator, and evaporator outlet superheat. The ejector pressure differential module is used to perform pressure differential analysis on the compressor's discharge pressure and suction pressure to obtain the compressor's ejector pressure differential. The oil return threshold determination module is used to determine the threshold of the oil return start-up conditions of the ejector based on the real-time oil level height and the evaporator outlet superheat, and obtain a determination result that meets the oil return start-up conditions. The valve opening calculation module is used to control and calculate the opening of the ejector's regulating valve based on the pressure difference and the preset oil level target value when the return oil start condition is met, so as to obtain the target opening of the ejector. The lubricating oil ejector module is used to power eject the lubricating oil at the bottom of the oil separator based on the target opening, so as to obtain the lubricating oil ejected back to the compressor. The ejector stop control module is used to control the operation of the ejector based on the real-time oil level, thereby obtaining the stop state of the ejector.

2. The air conditioning low-temperature refrigeration oil return system based on ejector and closed-loop control as described in claim 1, characterized in that, When the real-time parameter acquisition module performs real-time parameter acquisition on the air conditioning equipment to obtain the compressor discharge pressure, compressor suction pressure, real-time oil level in the oil separator, and evaporator outlet superheat, it is specifically used for: Based on the exhaust pressure transmitter of the air conditioning equipment compressor, the pressure of the refrigerant gas flow discharged by the compressor is detected in real time to obtain the exhaust pressure electrical signal of the compressor. Based on the suction pressure transmitter on the compressor suction line, the pressure of the refrigerant flow back to the compressor is detected in real time to obtain the suction pressure electrical signal of the compressor. The oil level in the oil separator is detected in real time to obtain an electrical signal of the real-time oil level. The superheat of the refrigerant at the evaporator outlet is directly detected to obtain an electrical signal indicating the superheat at the evaporator outlet.

3. The air conditioning low-temperature refrigeration oil return system based on ejector and closed-loop control as described in claim 1, characterized in that, When the ejector pressure differential module performs pressure differential analysis on the compressor's discharge pressure and suction pressure to obtain the compressor's ejector pressure differential, it is specifically used for: The compressor discharge pressure is used as the high-pressure input signal, and the compressor suction pressure is used as the low-pressure input signal, which are connected to the positive and negative input terminals of the compressor pressure comparator. The initial pressure difference signal of the compressor is obtained by performing a real-time subtraction operation on the high-pressure input signal and the low-pressure input signal. The initial pressure difference signal is filtered and amplified to obtain the conditioned pressure difference signal of the compressor. Zero-point calibration compensation is performed on the conditioned differential pressure signal to obtain the ejector pressure difference of the compressor.

4. The air conditioning low-temperature refrigeration oil return system based on ejector and closed-loop control as described in claim 1, characterized in that, When the oil return threshold determination module performs a threshold determination on the oil return start-up conditions of the ejector based on the real-time oil level and evaporator outlet superheat, and obtains a determination result that satisfies the oil return start-up conditions, it is specifically used for: Obtain the preset oil level determination threshold and the preset superheat determination threshold; The real-time oil level is compared with a preset oil level judgment threshold to obtain the comparison result of the real-time oil level. The superheat at the evaporator outlet is compared with the superheat determination threshold to obtain the comparison result of the superheat at the evaporator outlet. Based on the comparison results of the real-time oil level and the evaporator outlet superheat, it is confirmed that the oil return start-up conditions are met.

5. The air conditioning low-temperature refrigeration oil return system based on ejector and closed-loop control as described in claim 4, characterized in that, When the oil return threshold determination module performs a comparison based on the real-time oil level and the evaporator outlet superheat, and confirms that the oil return start-up conditions are met, it is specifically used for: When the real-time oil level is lower than the preset oil level threshold, the current operating frequency of the compressor is obtained; Based on the current operating frequency, a mapping query is performed on the return oil start-up oil level threshold to obtain the return oil start-up oil level threshold for the current operating frequency; The real-time oil level height and the return oil start-up oil level threshold are checked and determined to obtain the check and determination result of the real-time oil level height; When the verification result is that the real-time oil level is lower than the return oil start oil level threshold, the duration of the real-time oil level being lower than the return oil start oil level threshold is recorded and monitored to obtain the oil shortage duration of the real-time oil level. When the duration of oil shortage reaches a preset time threshold, the oil return start condition is confirmed to be met.

6. The air conditioning low-temperature refrigeration oil return system based on ejector and closed-loop control as described in claim 1, characterized in that, When the valve opening calculation module performs the function of controlling and calculating the opening of the ejector's regulating valve based on the pressure difference and a preset oil level target value when the return oil start condition is met, to obtain the target opening of the ejector, it is specifically used for: The deviation between the real-time oil level and the preset oil level target value is generated to obtain the oil level deviation signal of the real-time oil level. The equivalent cross-sectional area of ​​the ejector channel and the ejector fluid density of the ejector are obtained by querying the structural parameter library of the ejector. Substituting the ejector pressure difference, the equivalent cross-sectional area of ​​the ejector channel, and the ejector fluid density into the ejector flow rate-pressure difference correlation formula, the basic opening value of the ejector is obtained. The ejector flow rate-pressure difference correlation formula is as follows: ； The ejector pressure difference is denoted as The equivalent cross-sectional area of ​​the ejection channel is denoted as The ejector fluid density is denoted as , The flow coefficient reflects the resistance characteristics of the fluid as it passes through the ejector channel. The opening correction amount is calculated and generated based on the oil level deviation signal, the preset proportional coefficient, and the preset integral coefficient; The target opening of the ejector is obtained by superimposing the base opening value and the opening correction amount.

7. The air conditioning low-temperature refrigeration oil return system based on ejector and closed-loop control as described in claim 6, characterized in that, When the valve opening calculation module generates the opening correction amount based on the oil level deviation signal, a preset proportional coefficient, and a preset integral coefficient, it is specifically used for: The instantaneous value of the oil level deviation at the current sampling moment in the oil level deviation signal is sampled instantaneously and denoted as... , where n is the sequence number of the current sampling time; Based on the instantaneous value of the oil level deviation at the current sampling time, all the instantaneous values ​​of the oil level deviation are accumulated to generate a cumulative oil level deviation value. ; The proportionality coefficient is denoted as The integral coefficient is denoted as The sampling period is denoted as Substituting the above parameters into the following formula for calculating the opening correction, we obtain the opening correction amount, which is as follows: ； in, This is the opening correction amount at the current sampling time.

8. The air conditioning low-temperature refrigeration oil return system based on ejector and closed-loop control as described in claim 1, characterized in that, When the lubricating oil ejector module performs the function of dynamically ejecting the lubricating oil at the bottom of the oil separator based on the target opening degree, and obtaining the lubricating oil ejected back to the compressor, it is specifically used for: Based on the target opening, the opening of the electronic expansion valve of the ejector is adjusted to obtain the target valve opening. Based on the high-pressure fluid on / off valve of the ejector, the high-pressure refrigerant discharged from the compressor enters the ejector, and the nozzle of the ejector is accelerated and depressurized to obtain a low-pressure zone in the ejector suction chamber that is lower than the internal pressure of the oil separator; Based on the pressure difference between the low-pressure zone and the inside of the oil separator, the liquid lubricating oil deposited at the bottom of the oil separator is drawn and drained to obtain the lubricating oil in the ejector suction chamber. The lubricating oil and the high-pressure refrigerant are homogenized to obtain a two-phase fluid for the ejector. The two-phase fluid is pressure-transmitted to obtain lubricating oil that is injected back into the compressor.

9. The air conditioning low-temperature refrigeration oil return system based on ejector and closed-loop control as described in claim 1, characterized in that, When the ejector stop control module executes the function of stopping the ejector based on the real-time oil level to obtain the ejector's stop state, it specifically performs the following: The real-time oil level in the oil separator is monitored in real time to obtain the current monitoring value of the real-time oil level. The current monitoring value is compared with the preset stop oil level. When the current monitoring value reaches the preset stop oil level, a stop trigger command for the ejector is obtained. Based on the stop trigger command of the ejector, the on / off valve at the front end of the high-pressure fluid inlet of the ejector is closed to obtain the fully closed state of the on / off valve; Based on the fully closed state of the on / off valve, the inflow of high-pressure refrigerant discharged from the compressor is blocked, resulting in a stop state where the ejector stops ejecting.

10. A method for low-temperature refrigeration oil return in air conditioning based on ejector and closed-loop control, characterized in that, For use in an air conditioning low-temperature refrigeration oil return system based on ejector and closed-loop control as described in claim 1, the method is as follows: Ⅰ. Real-time parameter acquisition of the air conditioning equipment to obtain the operating parameters of the air conditioning equipment, such as compressor discharge pressure, compressor suction pressure, real-time oil level in the oil separator, and evaporator outlet superheat. II. Perform pressure differential analysis on the compressor's discharge pressure and suction pressure to obtain the ejector pressure differential of the compressor; III. Based on the real-time oil level and evaporator outlet superheat, a threshold determination is made for the oil return start-up conditions of the ejector to obtain a determination result that meets the oil return start-up conditions; IV. When the oil return start condition is met, based on the pressure difference and the preset oil level target value, the opening of the regulating valve of the ejector is controlled and calculated to obtain the target opening of the ejector; V. Based on the target opening degree, the lubricating oil at the bottom of the oil separator is dynamically ejected to obtain lubricating oil that is ejected back to the compressor; VI. Based on the real-time oil level, the working state of the ejector is controlled to stop, thereby obtaining the stop state of the ejector.

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