Method for equalizing the discharge temperature of a gas return controlled multi-compressor

Abstract

This application discloses a method for equalizing the exhaust temperature of multiple compressors using return gas control. The method includes: calculating the absolute exhaust temperature difference and suction superheat based on data acquired by an exhaust temperature sensor, a suction temperature sensor, and a low-pressure sensor; controlling the opening of multiple return gas proportional control valves based on the absolute exhaust temperature difference and suction superheat, thereby adjusting the exhaust temperature of the compressors to maintain a balance in the exhaust temperature of different compressors. This application can improve the effectiveness and accuracy of exhaust temperature equalization control.

Description

Technical Field

[0001] This application relates to, but is not limited to, the field of air conditioning technology, and in particular to a method for equalizing the exhaust temperature of multiple compressors by controlling the return gas. Background Technology

[0002] In air conditioning systems, parallel operation of multiple compressors offers advantages such as convenient energy regulation, low cost, and high partial load efficiency, and is currently widely used in the refrigeration industry. However, during actual operation of parallel operation of multiple compressors, due to differences in the flow path resistance of each compressor, individual performance differences, varying heat exchanger specifications, and different levels of installation standards, there are inherent deviations in the flow resistance of each return gas branch. In addition, the dynamic changes in the operating environment and system load cause the actual output capacity of each compressor to be different, further exacerbating the differences in the flow and pressure of the intake refrigerant, i.e., uneven refrigerant distribution.

[0003] Uneven refrigerant distribution directly leads to compressor load imbalance, resulting in uneven discharge temperatures. This, in turn, rapidly triggers a series of cascading failures, including compressor mechanical wear, motor overheating, liquid slugging, decreased system efficiency, and operational instability. Current technologies typically ignore the uneven resistance in the compressor's return airflow path and only offer coarse adjustments by changing the compressor frequency to reduce the discharge temperature difference. In scenarios with varying loads and compressor rotation leading to significant differences in return airflow between the two compressor sides, this approach cannot accurately adapt to the actual operating load differences between the high and low temperature compressors. The adjustment precision is low, and the lack of a compensation mechanism for uneven return airflow path resistance directly affects discharge temperature balance, causing compressor overheating and liquid slugging, ultimately impacting the reliability and lifespan of the air conditioning unit. Summary of the Invention

[0004] This application provides a method for equalizing the exhaust temperature of multiple compressors by controlling the return gas flow, which can improve the effectiveness and accuracy of exhaust temperature equalization control among compressors.

[0005] In a first aspect, embodiments of this application provide a method for equalizing the exhaust temperature of multiple compressors by controlling return gas flow, applied to an air conditioning system. The air conditioning system includes multiple compressors, multiple return gas proportional control valves, multiple exhaust temperature sensors, intake temperature sensors, and a low-pressure sensor. The intake temperature sensor and the low-pressure sensor are installed on the return gas main of the air conditioning system. Multiple return gas branches are branched from the return gas main, each return gas branch corresponding to one of the compressors. The return gas proportional control valve is installed on each return gas branch, and the return gas branches are symmetrically arranged. The method includes: The absolute exhaust temperature difference and intake superheat are calculated by analyzing the data obtained from the exhaust temperature sensor, the intake temperature sensor and the low-pressure sensor. The opening degree of multiple return gas proportional adjustment valves is controlled according to the absolute exhaust temperature difference and the intake superheat, thereby adjusting the exhaust temperature of the compressor so that the exhaust temperature of different compressors remains balanced.

[0006] Secondly, according to embodiments of this application, a device for equalizing the exhaust temperature of multiple compressors by controlling return gas is provided, applied to an air conditioning system. The air conditioning system includes multiple compressors, multiple return gas proportional control valves, multiple exhaust temperature sensors, intake temperature sensors, and a low-pressure sensor. The intake temperature sensor and the low-pressure sensor are installed on the return gas main of the air conditioning system. Multiple return gas branches are branched from the return gas main, each return gas branch corresponding to one of the compressors. The return gas proportional control valve is installed on each return gas branch, and the return gas branches are symmetrically arranged. The device includes: The preprocessing module is used to calculate the data acquired by the exhaust temperature sensor, the intake temperature sensor and the low-pressure sensor to obtain the absolute exhaust temperature difference and intake superheat. The regulating module is used to control the opening degree of multiple return gas proportional regulating valves according to the absolute exhaust temperature difference and the intake superheat, thereby regulating the exhaust temperature of the compressor.

[0007] Thirdly, an electronic device provided according to an embodiment of this application includes: At least one processor; At least one memory for storing at least one program; When at least one of the programs is executed by at least one of the processors, the method for equalizing the exhaust temperature of the return gas control multi-compressor according to any one of the first aspects is implemented.

[0008] Fourthly, according to the embodiments of the application, a computer-readable storage medium is provided, storing computer-executable instructions for executing a method for achieving exhaust temperature equalization of a multi-compressor with return gas control as described in any of the first aspects.

[0009] In summary, the method for equalizing the exhaust temperature of multiple compressors by controlling the return gas according to the above embodiments of this application is applied to an air conditioning system. The air conditioning system includes multiple compressors, multiple return gas proportional control valves, multiple exhaust temperature sensors, intake temperature sensors, and low-pressure sensors. An intake temperature sensor and a low-pressure sensor are installed on the return gas main of the air conditioning system. Multiple return gas branches are branched from the return gas main, each corresponding to a compressor. Return gas proportional control valves are installed on the return gas branches, and the return gas branches are symmetrically arranged. The method includes: calculating the absolute exhaust temperature difference and intake superheat based on the data obtained from the exhaust temperature sensor, intake temperature sensor, and low-pressure sensor; controlling the opening of the multiple return gas proportional control valves according to the absolute exhaust temperature difference and intake superheat, thereby adjusting the exhaust temperature of the compressors to maintain a balance in the exhaust temperature of different compressors. In this embodiment, an independent return gas proportional regulating valve is configured on each return gas branch, forming multiple branches. This ensures that the multiple return gas branches are independent of each other and do not cross-contaminate, and that the return gas branches are symmetrically arranged. This maintains the same flow resistance among the return gas branches, thus avoiding uneven refrigerant distribution caused by flow resistance in the hardware. Then, the absolute discharge temperature difference and suction superheat are used together to identify the uneven refrigerant distribution, thereby improving the accuracy of identification. At the same time, the refrigerant circulation conditions of the compressor are accurately matched, improving the effectiveness and accuracy of discharge temperature balance control. Attached Figure Description

[0010] Figure 1 This is a schematic diagram of refrigerant flow in an air conditioning system with two compressors according to one embodiment of this application; Figure 2 This is a schematic diagram of refrigerant flow in an air conditioning system with multiple compressors according to one embodiment of this application; Figure 3 This is a schematic diagram of the return air branch of an air conditioning system provided in one embodiment of this application; Figure 4 This is a flowchart of the steps of a method for equalizing the exhaust temperature of multiple compressors with return gas control according to an embodiment of this application; Figure 5 This application provides a flowchart of the steps for equalizing the exhaust temperature of two compressors in one embodiment; Figure 6 This application provides a flowchart of the steps for equalizing the exhaust temperature of multiple compressors in one embodiment; Figure 7 This is a hardware schematic diagram of an electronic device provided in one embodiment of this application. Detailed Implementation

[0011] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0012] It is understandable that although functional modules are divided in the device schematic diagram and a logical order is shown in the flowchart, in some cases, the steps shown or described may be performed in a different order than the module division in the device or the order in the flowchart. The terms "first," "second," etc., in the specification, claims, or the aforementioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence.

[0013] In air conditioning systems, parallel operation of multiple compressors offers advantages such as convenient energy regulation, low cost, and high partial load efficiency, and is currently widely used in the refrigeration industry. However, during actual operation of parallel operation of multiple compressors, due to differences in the flow path resistance of each compressor, individual performance differences, varying heat exchanger specifications, and different levels of installation standards, there are inherent deviations in the flow resistance of each return gas branch. In addition, the dynamic changes in the operating environment and system load cause the actual output capacity of each compressor to be different, further exacerbating the differences in the flow and pressure of the intake refrigerant, i.e., uneven refrigerant distribution.

[0014] Uneven refrigerant distribution directly leads to compressor load imbalance, resulting in uneven discharge temperatures. This, in turn, rapidly triggers a series of cascading failures, including compressor mechanical wear, motor overheating, liquid slugging, decreased system efficiency, and operational instability. Current technologies typically ignore the uneven resistance in the compressor's return airflow path and only offer coarse adjustments by changing the compressor frequency to reduce the discharge temperature difference. In scenarios with varying loads and compressor rotation leading to significant differences in return airflow between the two compressor sides, this approach cannot accurately adapt to the actual operating load differences between the high and low temperature compressors. The adjustment precision is low, and the lack of a compensation mechanism for uneven return airflow path resistance directly affects discharge temperature balance, causing compressor overheating and liquid slugging, ultimately impacting the reliability and lifespan of the air conditioning unit.

[0015] Based on this, the embodiments of this application provide a method for equalizing the exhaust temperature of multiple compressors by controlling the return gas, which can improve the effectiveness and accuracy of equalizing the exhaust temperature among compressors.

[0016] The method for equalizing the exhaust temperature of multiple compressors by controlling the return gas in this application embodiment is applied to an air conditioning system. The air conditioning system includes multiple compressors, multiple return gas proportional control valves, multiple exhaust temperature sensors, intake temperature sensors, and low-pressure sensors. An intake temperature sensor and a low-pressure sensor are installed on the return gas main of the air conditioning system. Multiple return gas branches are branched from the return gas main, each corresponding to a compressor. Return gas proportional control valves are installed on the return gas branches, and the return gas branches are symmetrically arranged. The method includes: calculating the absolute exhaust temperature difference and intake superheat based on data acquired by the exhaust temperature sensor, intake temperature sensor, and low-pressure sensor; controlling the opening of the multiple return gas proportional control valves based on the absolute exhaust temperature difference and intake superheat, thereby adjusting the exhaust temperature of the compressors to maintain a balance in the exhaust temperature of different compressors. In this embodiment, an independent return gas proportional control valve is configured on each return gas branch, forming multiple branches. This ensures that the multiple return gas branches are independent of each other and do not cross-contaminate, and that the return gas branches are symmetrically arranged. This maintains the same flow resistance among the return gas branches, thus avoiding uneven refrigerant distribution caused by flow resistance in the hardware. Then, the absolute discharge temperature difference and suction superheat are used together to identify the uneven refrigerant distribution, thereby improving the accuracy of identification. At the same time, the refrigerant circulation conditions of the compressor are accurately matched, improving the effectiveness and accuracy of discharge temperature balance control.

[0017] This application provides a method for equalizing the exhaust temperature of multiple compressors by controlling the return gas flow. The method is applied to an air conditioning system. The air conditioning system includes multiple compressors, multiple return gas proportional control valves, multiple exhaust temperature sensors, intake temperature sensors, and low-pressure sensors. An intake temperature sensor and a low-pressure sensor are installed on the return gas main of the air conditioning system. Multiple return gas branches are branched from the return gas main, and each return gas branch corresponds to a compressor. A return gas proportional control valve is installed on each return gas branch, and the return gas branches are symmetrically arranged.

[0018] It is understandable that an air conditioning system includes an outdoor unit heat exchanger, an outdoor unit fan, an expansion valve, a four-way valve, an indoor unit heat exchanger, an indoor unit fan, a gas-liquid separator, a shut-off valve, multiple compressors, multiple return gas proportional control valves, multiple exhaust temperature sensors (i.e., exhaust temperature sensors in the diagram), a high-pressure pressure sensor, an intake temperature sensor (i.e., intake temperature sensors in the diagram), a low-pressure sensor, and a filter.

[0019] For example, refer to Figure 1 and Figure 2As shown, in an air conditioning system, during cooling operation, the high-temperature refrigerant is compressed by the compressor and discharged. After passing through a four-way valve, the refrigerant sequentially passes through the outdoor unit heat exchanger, expansion valve, and indoor unit heat exchanger, and then returns to the gas-liquid separator through the four-way valve again. Finally, it splits into two paths, passing through the filter and the return gas proportional control valve, and returns to the compressor, thus completing the cooling cycle. During heating operation, the high-temperature refrigerant is compressed by the compressor and discharged. After passing through a four-way valve, the four-way valve is energized and reverses its direction. The refrigerant sequentially passes through the indoor unit heat exchanger, expansion valve, and outdoor unit heat exchanger, and then returns to the gas-liquid separator through the four-way valve again. Finally, it splits into two paths, passing through the filter and the return gas proportional control valve, and returns to the compressor, thus completing the heating cycle.

[0020] In air conditioning systems, when two (or more) compressors operate in parallel, the operating environment and system load change over time due to flow path resistance, individual compressor differences, or variations in heat exchanger size. In addition, differences in installation standards result in different output capacities of each compressor. This leads to significant deviations in the refrigerant flow and pressure states drawn into different compressors, resulting in some compressors having higher discharge superheat and others having lower discharge superheat. Consequently, there are large deviations in discharge temperature among different multi-split units, which affects the reliable operation of the parallel-running units.

[0021] Specifically, taking two compressors as an example, the two compressors are of the same model, but due to manufacturing tolerances or piping layout limitations: Compressor A has a shorter return gas line with fewer bends; compressor B has a longer return gas line with an additional U-bend and connector.

[0022] When both compressors are running simultaneously, after the refrigerant gas flows out of the evaporator, it preferentially chooses the branch with the least resistance. Therefore, the amount of refrigerant returning to compressor A will be significantly more than that of compressor B, resulting in more refrigerant entering compressor A than entering compressor B.

[0023] Because compressor A has a large return gas flow rate, the refrigerant residence time in the evaporator is relatively short, and heat exchange may be insufficient, resulting in a low suction superheat (the difference between the suction temperature and the corresponding saturation temperature at the evaporation pressure), typically around 5-8K. Conversely, because compressor B has a small return gas flow rate, the refrigerant flowing through the evaporator is slow and is overheated at the end of the evaporator, leading to an abnormally high suction superheat. Furthermore, due to insufficient suction volume and extremely high suction superheat, compressor B's discharge temperature rises rapidly during compression. In other words, the significant difference in suction superheat between compressors A and B directly results in a severe imbalance in the discharge temperatures of the two compressors.

[0024] However, compressors rely on the intake of low-temperature refrigerant gas to cool the motor. Insufficient gas intake in compressor B means a sharp deterioration in cooling effect, creating a vicious cycle of insufficient intake leading to poor cooling, which in turn leads to higher temperatures. This can cause the compressor's exhaust temperature to soar from the normal range (e.g., about 90°C) to 110°C or even higher. When the compressor exhaust temperature consistently or frequently exceeds a certain limit (e.g., 120°C), the refrigeration oil in the system will begin to carbonize and deteriorate, gradually losing its lubricating ability. This will ultimately lead to abnormal wear of critical moving parts such as the scroll plate, threatening the compressor's operational safety and service life.

[0025] Reference Figure 3 As shown, the air conditioning system of this embodiment includes multiple compressors, multiple return gas proportional control valves, multiple exhaust temperature sensors, intake temperature sensors, and a low-pressure sensor. An intake temperature sensor and a low-pressure sensor are installed on the return gas main of the air conditioning system. Multiple return gas branches branch from the return gas main, each corresponding to a compressor. An independent return gas proportional control valve is configured on each return gas branch, forming multiple branches. This ensures that the multiple return gas branches are independent of each other and do not cross-contaminate, and that the return gas branches are symmetrically arranged. This maintains the same flow resistance among the return gas branches, thus avoiding uneven refrigerant distribution caused by flow resistance in the hardware. This embodiment does not limit the specific structure of the exhaust and return gas mains of the air conditioning system; specific structures can be selected according to actual needs.

[0026] Specifically, the return gas branches adopt a symmetrical, equal-resistance independent return gas branch structure, satisfying the following: the pipe length and diameter from the return gas proportional regulating valve to the compressor return gas port are the same (i.e., L1=L2=……=Ln, G1=G2=……=Gn), the number of bends is equal (i.e., M1=M2=……=Mn), and the turning angles are consistent (α1(X1,Y1,Z1)=α2(X2,Y2,Z2)=……=αn(Xn,Yn,Zn), β1(X1,Y1,Z1)=β2(X2,Y2,Z2)=……=βn(Xn,Yn,Zn)); the whole is arranged in a mirror symmetry, so that the total flow resistance of each return gas branch is equal, eliminating the influence of differences in pipe structure on flow distribution.

[0027] For example, in this embodiment of the application, the diameter of the return gas proportional regulating valve is d, and the diameter of the compressor's suction port is ds, where d ≥ ds, thereby reducing the pressure drop resistance of the suction.

[0028] For example, when the unit is powered on, the proportional valve is adjusted to its set opening degree (B=B0) at the current step number, and then closed to B=B1 (Bmax0<B1). This ensures the valve is completely closed while avoiding excessive steps, completing the reset and zeroing initialization of the return gas proportional valve. The set opening degree can be [200, 350] pls, for example, in this control B0=200pls. Bmax0 is the maximum number of pulses corresponding to the maximum opening of the proportional valve, for example, in this control Bmax0=500pls.

[0029] After the user sets the temperature upon startup, the unit calculates the overall computing power requirement Q based on the indoor and outdoor ambient temperatures and the set temperature. This requirement is then compared to a preset capacity boundary Q1 built into the air conditioning system. This preset capacity boundary serves as the dividing line between single-compressor operation and multi-compressor operation. The preset capacity boundary can be derived from experimental testing and compressor specifications. For example, in this control, the value is [30, 900] hectowatts, and Q1 = 255 hectowatts. This embodiment does not impose such limitations and can be set according to actual needs.

[0030] When Q≤Q1, the air conditioning system operates with a single compressor. The compressor return gas proportional control valve stops when the number of steps Bs1=0, and the compressor return gas proportional control valve opens when the number of steps Br=Bmax0.

[0031] When Q > Q1, the system operates with dual compressors. If it is determined to be the first time dual compressors are running, the number of steps to open the return gas proportional control valve of the started compressor is B = Bs2, Bs2 > Bmax0 / 2 (Bs2 takes the value [300, 450] pls, for example, in this control Bs2 = 350pls).

[0032] In some embodiments, refer to Figure 4 As shown, the method for equalizing the exhaust temperature of multiple compressors by controlling the return gas includes, but is not limited to, the following steps: Step S100: Calculate the data obtained from the exhaust temperature sensor, intake temperature sensor and low-pressure sensor to obtain the absolute exhaust temperature difference and intake superheat. Step S110: The opening of multiple return gas proportional adjustment valves is controlled according to the absolute exhaust temperature difference and intake superheat, thereby adjusting the exhaust temperature of the compressor so that the exhaust temperature of different compressors remains balanced.

[0033] Understandably, while maintaining equal total flow resistance in the return gas branch in terms of hardware, the air conditioning system in this application embodiment monitors the exhaust temperature of each compressor in real time through an exhaust temperature sensor, monitors the intake temperature through an intake temperature sensor, and monitors the low pressure through a low pressure sensor. Based on the collected data, the absolute exhaust temperature difference and intake superheat are calculated, providing a basis for subsequent adjustment of the compressor's exhaust temperature based on the exhaust temperature difference and intake superheat. Furthermore, considering that uneven exhaust temperature is not necessarily caused by uneven refrigerant distribution, existing technologies only coarsely adjust the compressor frequency or judge uneven refrigerant distribution solely based on the exhaust temperature difference and control the return gas, which may disrupt the existing stable operating conditions. This application's embodiment uses both absolute exhaust temperature difference and suction superheat to identify uneven refrigerant distribution, eliminating ineffective adjustments triggered by a single exhaust temperature difference, avoiding meaningless operations that interfere with system stability, and precisely matching the compressor's refrigerant cycle conditions, thereby fundamentally improving the effectiveness and accuracy of exhaust temperature balance control.

[0034] It is understandable that if the exhaust temperature difference exceeds the threshold, but the suction superheat is within the target range of 3-8K, it indicates that the refrigerant circulation and return gas status of the system are normal. That is, the exhaust temperature difference is not necessarily caused by refrigerant distribution imbalance. If the suction superheat is less than the target range of 3K, adjusting the throttle valve is an ineffective operation and will instead disrupt the existing stable operating conditions, causing pressure and flow fluctuations. When the suction superheat deviates from the target range, it will directly lead to abnormal refrigerant compression ratio and return gas flow of the compressor, thereby causing exhaust temperature difference imbalance. That is, there is a coupling relationship between exhaust temperature and suction superheat. When both meet the abnormal conditions at the same time, it indicates that this is the actual operating condition that needs adjustment, ensuring the root cause of the adjustment problem. The embodiment of this application uses the linkage trigger of absolute exhaust temperature difference and suction superheat. By eliminating the ineffective adjustment triggered by a single exhaust temperature difference, the frequency of meaningless adjustment of the throttle valve is greatly reduced. This avoids frequent valve operation, eliminates system oscillation caused by ineffective adjustment, and improves the response accuracy of the control logic.

[0035] In some embodiments, calculating the absolute exhaust temperature difference and intake superheat from the data acquired by the exhaust temperature sensor, intake temperature sensor, and low-pressure sensor includes: acquiring the exhaust temperature of each compressor through the exhaust temperature sensor and calculating the absolute exhaust temperature difference based on the exhaust temperature; and calculating the intake superheat from the intake temperature acquired by the intake temperature sensor and the low-pressure sensor.

[0036] It is understood that in this embodiment of the application, the exhaust temperature of each compressor is collected by the exhaust temperature sensor, and the absolute value of the difference between the exhaust temperatures is calculated as the absolute exhaust temperature difference; the intake temperature of the compressor is collected by the intake temperature sensor, and the low pressure is collected by the low pressure sensor. Finally, the intake superheat is calculated by the intake temperature and the low pressure.

[0037] In some embodiments, calculating the intake superheat based on the intake temperature collected by the intake temperature sensor and the low pressure collected by the low pressure sensor includes: looking up the low pressure in a preset pressure-enthalpy relationship mapping table corresponding to the air conditioning system to obtain the saturation temperature corresponding to the low pressure; and calculating the intake superheat based on the saturation temperature and the intake temperature.

[0038] Understandably, a preset pressure-enthalpy relationship mapping table is constructed based on the pressure-enthalpy diagram corresponding to the air conditioning system. Then, the saturation temperature corresponding to the low pressure is obtained by looking up the table from the preset pressure-enthalpy relationship mapping table. The suction temperature and the saturation temperature are subtracted to obtain the suction superheat.

[0039] Specifically, the suction superheat satisfies the following expression: ΔSH=Ts-Ts0, where ΔSH is the suction superheat, Ts is the suction temperature, Ts0 is the saturation temperature, and the saturation temperature Ts0 is the saturation temperature corresponding to the low pressure in the preset pressure-enthalpy relationship mapping table of the system refrigerant according to the pressure-enthalpy diagram. The value range of the saturation temperature Ts0 can be [-50, 30]℃.

[0040] In some embodiments, controlling the opening of multiple return gas proportional control valves based on the absolute exhaust temperature difference and the intake superheat includes: when the absolute exhaust temperature difference is greater than a preset temperature difference threshold and the intake superheat is greater than a preset superheat threshold, obtaining a preset temperature difference range corresponding to the absolute exhaust temperature difference; and adjusting the opening of the return gas proportional control valves according to the adjustment strategy associated with the preset temperature difference range.

[0041] It is understood that this embodiment of the application, by superimposing exhaust temperature and intake superheat (SH) for joint judgment, determines that the adjustment trigger condition is met only when the preset temperature difference threshold T0 < absolute exhaust temperature difference ΔT and the preset superheat threshold SH0 < intake superheat ΔSH, and initiates the adjustment process of the return gas proportional control valve (i.e., throttle valve). Then, the preset temperature difference range corresponding to the absolute exhaust temperature difference is obtained. Different temperature difference ranges are associated with different adjustment strategies. The temperature difference-graded adjustment strategy sets precise adjustment for small temperature differences and rapid temperature control for large temperature differences. Then, the opening of the return gas proportional control valve is adjusted according to the adjustment strategy associated with the preset temperature difference range. In this way, the temperature difference-graded adjustment strategy can achieve precise adjustment for small temperature differences and rapid temperature control for large temperature differences, significantly reducing adjustment lag and overshoot problems, and significantly improving the accuracy of exhaust temperature balance control.

[0042] In some embodiments, the adjustment strategy corresponds to a graded adjustment coefficient, which includes a first high-temperature side coefficient corresponding to the high-temperature side adjustment valve and a first low-temperature side coefficient corresponding to the low-temperature side adjustment valve. The first high-temperature side coefficient is greater than the first low-temperature side coefficient. Adjusting the opening of the return gas proportional adjustment valve according to the adjustment strategy associated with the preset temperature difference range includes: using the return gas proportional adjustment valve of the return gas branch where the compressor with the highest exhaust temperature is located as the high-temperature side adjustment valve, and using the return gas adjustment valve corresponding to the lowest exhaust temperature as the low-temperature side adjustment valve; adjusting the high-temperature side adjustment valve based on the first high-temperature side coefficient, and simultaneously adjusting the low-temperature side adjustment valve based on the first low-temperature side coefficient.

[0043] It is understood that the adjustment strategy associated with the preset temperature difference range in this application embodiment includes a first high-temperature side coefficient corresponding to the high-temperature side regulating valve and a first low-temperature side coefficient corresponding to the low-temperature side regulating valve, with the first high-temperature side coefficient being greater than the first low-temperature side coefficient. Then, the high-temperature side regulating valve is adjusted based on the first high-temperature side coefficient, and simultaneously, the low-temperature side regulating valve is adjusted synchronously based on the first low-temperature side coefficient. A larger first high-temperature side coefficient means a greater increase in the opening of the high-temperature side valve to quickly increase its refrigerant flow; a smaller first low-temperature side coefficient means a smaller decrease in the opening of the low-temperature side valve to avoid excessive reduction in its flow rate and causing a new imbalance. This achieves a graded adjustment effect of large-step rapid adjustment when the temperature difference is large and small-step fine adjustment when the temperature difference is small. By simultaneously but differentially adjusting the high and low temperature side valves based on different coefficients, the redistribution of the return gas volume can be precisely controlled. In this application embodiment, the return gas proportional valve at the intermediate temperature is not adjusted; it can be controlled according to actual needs.

[0044] In some embodiments, adjusting the high-temperature side regulating valve based on a first high-temperature side coefficient and simultaneously adjusting the low-temperature side regulating valve based on a first low-temperature side coefficient includes: multiplying the opening degree of the high-temperature side regulating valve at the current moment by a weighted sum of the first high-temperature side coefficient to obtain the high-temperature side regulation degree, and increasing the opening degree of the high-temperature side regulating valve based on the high-temperature side regulation degree; multiplying the opening degree of the low-temperature side regulating valve at the current moment by a weighted sum of the first low-temperature side coefficient to obtain the low-temperature side regulation degree, and decreasing the opening degree of the low-temperature side regulating valve based on the low-temperature side regulation degree.

[0045] It is understood that in this embodiment, the opening of the high-temperature side regulating valve is increased to rapidly increase its refrigerant gas volume; at the same time, the opening of the low-temperature side regulating valve is reduced to decrease its refrigerant gas volume, so that the exhaust temperature on that side rises moderately, thereby effectively reducing the exhaust temperature difference between the high-temperature side and the low-temperature side and achieving a balance in the exhaust temperature field.

[0046] In some embodiments, after adjusting the opening of the return gas proportional control valve according to the adjustment strategy associated with the preset temperature difference range, the method further includes: starting a timer of the air conditioning system to keep time; during the preset pressure holding and stabilization period, controlling the opening of the return gas proportional control valve to remain unchanged, while suspending the adjustment trigger judgment of the return gas proportional control valve.

[0047] Understandably, after the return gas proportional control valve completes the opening adjustment, the system control enters a preset pressure holding and stabilization period of time t (time t takes values ​​of [10,300] s, for example t=100s). During this period, the current valve opening is maintained and no adjustment operation is performed, so that the system return gas flow and pipeline pressure are dynamically adapted, avoiding system fluctuations caused by real-time adjustment.

[0048] Reference Figure 5As shown, taking two compressors operating in parallel as an example, the following steps are taken to adjust the exhaust temperature: The system monitors the exhaust temperatures Td1 and Td2, intake temperatures Ts, and low-pressure Ps of compressors 1 and 2 in real time, and the steps of the return gas proportional control valves corresponding to the two compressors are set to B1 and B2 respectively. The absolute exhaust temperature difference ΔT = |Td1-Td2| is taken as the absolute value of the difference between the exhaust temperatures on the high-temperature side and the low-temperature side of the dual compressor. The low-pressure of the system is measured by the low-pressure sensor. The saturation temperature is selected from the preset pressure-enthalpy relationship mapping table of the pressure-enthalpy diagram based on the low-pressure pressure. Then, the difference between the suction temperature and the saturation temperature is taken as the suction superheat. The suction superheat satisfies the following expression: ΔSH = Ts - Ts0, where ΔSH is the suction superheat, Ts is the suction temperature, and Ts0 is the saturation temperature. The combined judgment of exhaust temperature and intake superheat (SH) is used. Only when T0 < ΔT and SH0 < ΔSH is it determined that the return gas proportional valve adjustment trigger condition is met. Determine the corresponding exhaust temperature and return gas ratio regulating valves for the high and low temperature sides, and name and assign values ​​according to high and low temperature. If the exhaust temperature Td1 corresponding to compressor 1 is greater than the exhaust temperature Td2 corresponding to compressor 2, then the high temperature side regulating valve BH=B1 and the low temperature side regulating valve BL=B2; otherwise, the high temperature side regulating valve BH=B2 and the low temperature side regulating valve BL=B1. Based on the range of the absolute exhaust temperature difference ΔT, temperature difference grading adjustment is performed, and a synchronous adjustment strategy (open valve on the high-temperature side, close valve on the low-temperature side) is sent to the high- and low-temperature side return gas regulating valves: Taking the preset temperature difference range as [T0, T1] as an example, when T0 < ΔT < T1 (T1 takes the value [3, 20]℃), the opening degree of the high temperature side regulating valve at the current moment and the weighted multiplication of the first high temperature side coefficient are multiplied to obtain the high temperature side regulation degree, and the opening degree of the high temperature side regulating valve is increased based on the high temperature side regulation degree. The opening degree of the high temperature side regulating valve after adjustment satisfies the following expression: BH+1 = BH + [H1 * BH], where BH+1 is the opening degree of the high temperature side regulating valve after adjustment, BH is the opening degree of the high temperature side regulating valve at the current moment, and H1 is the first high temperature side coefficient; The opening degree of the low-temperature side regulating valve at the current moment is multiplied by the weighted sum of the first low-temperature side coefficient to obtain the low-temperature side regulation degree. The opening degree of the low-temperature side regulating valve is reduced based on the low-temperature side regulation degree. The opening degree of the low-temperature side regulating valve after adjustment satisfies the following expression: BL+1=BL-[L1*BL], H1>L1, where BL+1 is the opening degree of the low-temperature side regulating valve after adjustment, BL is the opening degree of the low-temperature side regulating valve at the current moment, and L1 is the first low-temperature side coefficient. Taking the preset temperature difference range as [0, T1] as an example, when T1 < ΔT, the opening degree of the high-temperature side regulating valve at the current moment is multiplied by the weighted sum of the second high-temperature side coefficient to obtain the high-temperature side regulation degree. Based on the high-temperature side regulation degree, the opening degree of the high-temperature side regulating valve is increased. The opening degree of the high-temperature side regulating valve after adjustment satisfies the following expression: BH+1 = BH + [H2 * BH], where BH+1 is the opening degree of the high-temperature side regulating valve after adjustment, BH is the opening degree of the high-temperature side regulating valve at the current moment, and H2 is the second high-temperature side coefficient. The opening degree of the low-temperature side regulating valve at the current moment is multiplied by the weighted sum of the second low-temperature side coefficient to obtain the low-temperature side regulation degree. Based on the low-temperature side regulation degree, the opening degree of the low-temperature side regulating valve is reduced. The opening degree of the low-temperature side regulating valve after regulation satisfies the following expression: BL+1=BL-[L2*BL], H2>L2, where BL+1 is the opening degree of the low-temperature side regulating valve after regulation, BL is the opening degree of the low-temperature side regulating valve at the current moment, and L2 is the second low-temperature side coefficient. If the condition is not met, maintain the current valve opening and continue to collect and determine data in a loop. After the return gas regulating valve completes the opening adjustment, the system control enters a pressure holding and stabilization period of time t (time t takes values ​​of [10,300] s, for example t=100s). During this period, the current valve opening is maintained and no adjustment operation is performed, so that the system return gas flow and pipeline pressure are dynamically adapted, avoiding system fluctuations caused by real-time adjustment.

[0049] Reference Figure 6 As shown, taking multiple compressors operating in parallel as an example, the following steps are taken to adjust the exhaust temperature: At this time, the system monitors compressors 1, 2, ... n in real time, their exhaust temperatures Td1, Td2, ... Tdn, their intake temperature Ts, their low-pressure pressure Ps, and their return gas proportional control valve steps B1, B2, ... Bn. Then, it compares the exhaust temperatures Td1, Td2, ... Tdn of all started compressors, takes the maximum exhaust temperature Tdmax = max{Td1, Td2, ... Tdn}, takes the minimum exhaust temperature Tdmin = min{Td1, Td2, ... Tdn}, and marks the corresponding compressor's return gas proportional control valve steps Bmax and Bmin. The absolute exhaust temperature difference ΔT = |Tdmax - Tdmin| is calculated from the exhaust temperatures of the compressor's highest and lowest temperatures. The suction superheat ΔSH = Ts - Ts0 (where the saturation temperature Ts0 takes a value of [-50, 30]℃, and the saturation temperature Ts0 is the saturation temperature of the system refrigerant corresponding to the low-pressure pressure in the pressure-enthalpy diagram. The system low-pressure pressure is measured by the low-pressure pressure sensor). The combined judgment of exhaust temperature and intake superheat (SH) is used. Only when T0 < ΔT and SH0 < ΔSH (T0 takes values ​​of [3,8]℃, SH0 takes values ​​of [1,5]℃, for example, in this control T0=3℃, SH0=2℃) is it determined that the adjustment trigger condition is met and the throttle valve adjustment process is started. Determine the exhaust temperature and return gas proportional control valve corresponding to the highest and lowest temperature sides, and name and assign values ​​according to the highest and lowest temperatures. Then BH=Bmax, BL=Bmin. Then, as mentioned in the dual compressor control, according to the range of ΔT, perform temperature difference graded adjustment and send synchronous adjustment commands to the high and low temperature side return gas control valves (open valve on high temperature side, close valve on low temperature side): when T0<ΔT<T1 (T1 takes the value [3,20]℃, for example, in this control T1=6℃), BH+1=BH+[H1*BH], BL+1=BL -[L1*BL], (H1>L1, H2>H1); when T1<ΔT, then BH+1=BH+[H2*BH], BL+1=BL-[L2*BL], (H2>L2, H2>H1), (coefficients H1, H2, L1, L2 are graded adjustment coefficients, derived from experimental tests. The corresponding throttle valve adjustment coefficients are matched according to different graded ranges of compressor exhaust temperature difference ΔT, with values ​​of [1, 30]. For example, coefficients H1=5%, L1=3%, H2=8%, L2=5%). If the condition is not met, maintain the current valve opening and continue to collect and determine data in a loop. After the return gas regulating valve completes its opening adjustment, the system control enters a pressure holding period of time t (the longer the time value, the larger the number of compressors n, the longer the time value, with time t ranging from 10 to 300 seconds, for example, t=120 seconds). During this period, the current valve opening is maintained, and no adjustment operation is performed, allowing the system return gas flow and pipeline pressure to dynamically adapt and avoid system fluctuations caused by immediate adjustments. By matching the step size according to the temperature difference range, the temperature difference of the highest low-temperature compressor is rapidly rotated for temperature control and precise adjustment, ultimately achieving rapid and balanced control of the exhaust temperature of multiple compressors.

[0050] This application provides a device for equalizing the exhaust temperature of multiple compressors by controlling the return gas flow, applied to an air conditioning system. The air conditioning system includes multiple compressors, multiple return gas proportional control valves, multiple exhaust temperature sensors, intake temperature sensors, and low-pressure sensors. Intake temperature sensors and low-pressure sensors are installed on the return gas main of the air conditioning system. Multiple return gas branches are branched from the return gas main, each corresponding to a compressor. Return gas proportional control valves are installed on the return gas branches, and the return gas branches are symmetrically arranged. The device includes: The preprocessing module is used to calculate the absolute exhaust temperature difference and intake superheat based on the data obtained from the exhaust temperature sensor, intake temperature sensor and low pressure sensor. The regulating module controls the opening of multiple return gas proportional regulating valves based on the absolute exhaust temperature difference and intake superheat, thereby regulating the compressor's exhaust temperature.

[0051] It is understood that the embodiments of the device for equalizing the exhaust temperature of multiple compressors with return gas control in this application are the same as the embodiments of the method for equalizing the exhaust temperature of multiple compressors with return gas control described above, and will not be repeated here.

[0052] This application also provides an electronic device, which includes a memory and a processor. The memory stores a computer program, and the processor executes the computer program to implement the above-described method for equalizing the exhaust temperature of multiple compressors under return gas control. This electronic device can be any smart terminal, including tablet computers, in-vehicle computers, etc.

[0053] Please see Figure 7 , Figure 7 The hardware structure of an electronic device according to another embodiment is illustrated. The electronic device includes: The processor 701 can be implemented using a general-purpose CPU (Central Processing Unit), microprocessor, application-specific integrated circuit (ASIC), or one or more integrated circuits, and is used to execute relevant programs to implement the technical solutions provided in the embodiments of this application. The memory 702 can be implemented as a read-only memory (ROM), a static storage device, a dynamic storage device, or a random access memory (RAM). The memory 702 can store the operating system and other application programs. When the technical solutions provided in the embodiments of this specification are implemented through software or firmware, the relevant program code is stored in the memory 702 and is called and executed by the processor 701 to execute the method for equalizing the exhaust temperature of a multi-compressor with return gas control according to the embodiments of this application. The input / output interface 703 is used to implement information input and output; The communication interface 704 is used to enable communication and interaction between this device and other devices. Communication can be achieved through wired means (such as USB, Ethernet cable, etc.) or wireless means (such as mobile network, WIFI, Bluetooth, etc.). Bus 705 transmits information between various components of the device (e.g., processor 701, memory 702, input / output interface 703, and communication interface 704); The processor 701, memory 702, input / output interface 703, and communication interface 704 are connected to each other within the device via bus 705.

[0054] In some embodiments, this application also provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the above-described method for equalizing the exhaust temperature of multiple compressors with return gas control.

[0055] Memory, as a non-transitory computer-readable storage medium, can be used to store non-transitory software programs and non-transitory computer-executable programs. Furthermore, memory may include high-speed random access memory, and may also include non-transitory memory, such as at least one disk storage device, flash memory device, or other non-transitory solid-state storage device. In some embodiments, memory may optionally include memory remotely located relative to the processor, and these remote memories can be connected to the processor via a network. Examples of such networks include, but are not limited to, the Internet, intranets, local area networks, mobile communication networks, and combinations thereof.

[0056] The embodiments described in this application are for the purpose of more clearly illustrating the technical solutions of the embodiments of this application, and do not constitute a limitation on the technical solutions provided by the embodiments of this application. As those skilled in the art will know, with the evolution of technology and the emergence of new application scenarios, the technical solutions provided by the embodiments of this application are also applicable to similar technical problems.

[0057] Those skilled in the art will understand that the technical solutions shown in the figures do not constitute a limitation on the embodiments of this application, and may include more or fewer steps than shown, or combine certain steps, or different steps.

[0058] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs.

[0059] Those skilled in the art will understand that all or some of the steps in the methods disclosed above, as well as the functional modules / units in the systems and devices, can be implemented as software, firmware, hardware, or suitable combinations thereof.

[0060] The terms “first,” “second,” “third,” “fourth,” etc. (if present) in the specification and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms “comprising” and “having,” and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0061] It should be understood that in this application, "at least one (item)" means one or more, and "more than" means two or more. "And / or" is used to describe the relationship between related objects, indicating that three relationships can exist. For example, "A and / or B" can represent three cases: only A exists, only B exists, and both A and B exist simultaneously, where A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects are in an "or" relationship. "At least one (item) of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, at least one (item) of a, b, or c can represent: a, b, c, "a and b", "a and c", "b and c", or "a and b and c", where a, b, and c can be single or multiple.

[0062] In the several embodiments provided in this application, it should be understood that the disclosed apparatus and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of the units described above is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or units may be electrical, mechanical, or other forms.

[0063] The units described above as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0064] Furthermore, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0065] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes multiple instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods of the various embodiments of this application. The aforementioned storage medium includes various media capable of storing programs, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

Claims

1. A method for equalizing the exhaust temperature of multiple compressors by controlling the return gas flow, characterized in that, The method is applied to an air conditioning system, which includes multiple compressors, multiple return gas proportional control valves, multiple exhaust temperature sensors, intake temperature sensors, and a low-pressure sensor. The intake temperature sensor and the low-pressure sensor are installed on the return gas main of the air conditioning system. Multiple return gas branches are branched from the return gas main, each corresponding to one of the compressors. The return gas proportional control valves are installed on the return gas branches, and the return gas branches are symmetrically arranged. The absolute exhaust temperature difference and intake superheat are calculated by analyzing the data obtained from the exhaust temperature sensor, the intake temperature sensor and the low-pressure sensor. The opening degree of multiple return gas proportional adjustment valves is controlled according to the absolute exhaust temperature difference and the intake superheat, thereby adjusting the exhaust temperature of the compressor so that the exhaust temperature of different compressors remains balanced.

2. The method for equalizing the exhaust temperature of multiple compressors with return gas control according to claim 1, characterized in that, The calculation of the absolute exhaust temperature difference and intake superheat based on the data acquired by the exhaust temperature sensor, the intake temperature sensor, and the low-pressure sensor includes: The exhaust temperature of each compressor is collected by the exhaust temperature sensor, and the absolute exhaust temperature difference is calculated based on the exhaust temperature. The inhalation superheat is calculated using the inhalation temperature collected by the inhalation temperature sensor and the low-pressure collected by the low-pressure sensor.

3. The method for equalizing the exhaust temperature of multiple compressors with return gas control according to claim 2, characterized in that, The calculation of the inhalation superheat based on the inhalation temperature collected by the inhalation temperature sensor and the low-pressure collected by the low-pressure sensor includes: The saturation temperature corresponding to the low pressure is obtained by looking up the preset pressure-enthalpy relationship mapping table corresponding to the air conditioning system based on the low pressure. The intake superheat is calculated based on the saturation temperature and the intake temperature.

4. The method for equalizing the exhaust temperature of multiple compressors with return gas control according to claim 1, characterized in that, The control of the opening degree of the plurality of return gas proportional regulating valves based on the absolute exhaust temperature difference and the intake superheat includes: When the absolute exhaust temperature difference is greater than a preset temperature difference threshold and the intake superheat is greater than a preset superheat threshold, a preset temperature difference range corresponding to the absolute exhaust temperature difference is obtained. The opening degree of the return gas proportional control valve is adjusted according to the adjustment strategy associated with the preset temperature difference range.

5. The method for equalizing the exhaust temperature of multiple compressors with return gas control according to claim 4, characterized in that, The adjustment strategy corresponds to a graded adjustment coefficient, which includes a first high-temperature side coefficient corresponding to the high-temperature side adjustment valve and a first low-temperature side coefficient corresponding to the low-temperature side adjustment valve. The first high-temperature side coefficient is greater than the first low-temperature side coefficient. Adjusting the opening of the return gas proportional adjustment valve according to the adjustment strategy associated with the preset temperature difference range includes: The return gas proportional regulating valve of the return gas branch where the compressor with the highest exhaust temperature is located is designated as the high-temperature side regulating valve, and the return gas regulating valve with the lowest exhaust temperature is designated as the low-temperature side regulating valve. The high-temperature side regulating valve is adjusted based on the first high-temperature side coefficient, and the low-temperature side regulating valve is adjusted synchronously based on the first low-temperature side coefficient.

6. The method for equalizing the exhaust temperature of multiple compressors with return gas control according to claim 5, characterized in that, The step of adjusting the high-temperature side regulating valve based on the first high-temperature side coefficient and simultaneously adjusting the low-temperature side regulating valve based on the first low-temperature side coefficient includes: The opening degree of the high-temperature side regulating valve at the current moment is multiplied by the weighted sum of the first high-temperature side coefficient to obtain the high-temperature side regulation degree, and the opening degree of the high-temperature side regulating valve is increased based on the high-temperature side regulation degree. The opening degree of the low-temperature side regulating valve at the current moment is multiplied by the weighted average of the first low-temperature side coefficient to obtain the low-temperature side regulation degree, and the opening degree of the low-temperature side regulating valve is reduced based on the low-temperature side regulation degree.

7. The method for equalizing the exhaust temperature of multiple compressors with return gas control according to claim 4, characterized in that, After adjusting the opening degree of the return gas proportional control valve according to the adjustment strategy associated with the preset temperature difference range, the method further includes: Start the timer of the air conditioning system to begin timing; During the preset pressure holding and stabilization period, the opening degree of the return gas proportional regulating valve is kept constant, while the adjustment trigger judgment of the return gas proportional regulating valve is suspended.

8. A device for equalizing the exhaust temperature of multiple compressors by controlling the return gas flow, characterized in that, An air conditioning system is used in which multiple compressors, multiple return gas proportional control valves, multiple exhaust temperature sensors, intake temperature sensors, and low-pressure sensors are included. The intake temperature sensors and low-pressure sensors are installed on the return gas main of the air conditioning system. Multiple return gas branches branch from the return gas main, each corresponding to one of the compressors. The return gas proportional control valves are installed on the return gas branches, which are symmetrically arranged. The device includes: The preprocessing module is used to calculate the data acquired by the exhaust temperature sensor, the intake temperature sensor and the low-pressure sensor to obtain the absolute exhaust temperature difference and intake superheat. The regulating module is used to control the opening degree of multiple return gas proportional regulating valves according to the absolute exhaust temperature difference and the intake superheat, thereby regulating the exhaust temperature of the compressor.

9. An electronic device, characterized in that, include: At least one processor; At least one memory for storing at least one program; When at least one of the programs is executed by at least one of the processors, the method for equalizing the exhaust temperature of a multi-compressor with return gas control as described in any one of claims 1 to 7 is implemented.

10. A computer-readable storage medium storing computer-executable instructions, characterized in that, The computer-executable instructions are used to execute the method for equalizing the exhaust temperature of the return gas control multi-compressor according to any one of claims 1 to 7.

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