Method for determining exhaust gas temperature and air conditioning system

Abstract

The application provides a method for determining exhaust temperature and an air conditioning system. The method comprises the following steps: a parameter acquisition step: acquiring an oil return temperature Tk, a high-pressure pressure Hp and a low-pressure pressure Lp; a data processing step: calculating a compression ratio Px of the compressor according to the high-pressure pressure Hp and the low-pressure pressure Lp; calculating a theoretical exhaust temperature Tp' of the compressor according to a preset relationship between the low-pressure pressure Lp, the compression ratio Px, the oil return temperature Tka and the theoretical exhaust temperature Tp'; an updating step: taking the data processing result of the data processing step as an actual exhaust temperature Tp of the compressor. The low-pressure pressure, the high-pressure pressure and the oil return temperature data are acquired, and the theoretical exhaust temperature of the compressor is obtained through operation, so that the operation of the compressor and the air conditioning system can be controlled according to the theoretical exhaust temperature, the exhaust protection is started in time when the exhaust fault occurs, and the stable operation of the air conditioning system and the service life of the compressor are ensured.

Description

Technical Field

[0001] This invention relates to the field of air conditioning, specifically to a method for determining exhaust temperature and an air conditioning system. Background Technology

[0002] In existing air conditioning systems, exhaust temperature sensors are typically used to detect the compressor's exhaust temperature. If the exhaust temperature detection device malfunctions, such as open circuit, short circuit, or detection drift, the true exhaust temperature of the refrigeration system cannot be effectively obtained. This directly affects the opening of the electronic expansion valve, the system's exhaust protection action, and the compressor's operating frequency, preventing the air conditioning system from reaching its optimal capacity and efficiency. In some extreme conditions, it may even fail to protect the air conditioning system in time, leading to compressor burnout, electrical damage, and other issues.

[0003] When existing exhaust temperature sensors malfunction, the following solutions are available:

[0004] 1. If the exhaust temperature sensor is open-circuited or short-circuited, the machine will shut down immediately for protection.

[0005] 2. When the exhaust temperature drifts, specify a minimum electronic expansion valve opening or determine a maximum target exhaust temperature to prevent shut-off, excessively high exhaust temperature, etc.

[0006] In Option 1 above, the air conditioning system prototype cannot operate during factory testing. Therefore, the fault will only be discovered when the user uses the product, affecting the user experience and increasing after-sales maintenance costs.

[0007] In Scheme 2 above, the opening of the electronic expansion valve cannot be effectively adjusted according to the prescribed logic, which seriously affects the capacity and energy efficiency of the air conditioning system. The exhaust protection cannot act in time, which may cause the compressor to burn out. Summary of the Invention

[0008] To address the above problems, this invention provides a method for determining exhaust temperature and an air conditioning system. When the exhaust temperature sensor fails, it can obtain low-pressure, high-pressure, and return oil temperature data and calculate the theoretical exhaust temperature of the compressor. Based on the theoretical exhaust temperature, the operation of the compressor and the air conditioning system can be controlled. When an exhaust failure occurs, exhaust protection can be activated in a timely manner to ensure the stable operation of the air conditioning system and the service life of the compressor.

[0009] This invention provides a method for determining the exhaust temperature of an air conditioning system. The air conditioning system includes a compressor, a four-way valve, a first heat exchanger, a throttling element, and a second heat exchanger connected in sequence to form a refrigerant cycle. It also includes:

[0010] Oil temperature sensor, used to detect the compressor's return oil temperature Tk;

[0011] High-pressure sensor used to detect the high-pressure Hp of the air conditioning system;

[0012] A low-pressure sensor is used to detect the low-pressure Lp of an air conditioning system.

[0013] Methods for determining exhaust temperature include:

[0014] Frequency acquisition steps: Obtain the compressor's operating frequency:

[0015] Frequency determination steps: Determine if the operating frequency is less than the specified frequency; if the operating frequency is not less than the specified frequency, proceed to the parameter acquisition step; if the operating frequency is less than the specified frequency, return to the frequency acquisition step.

[0016] Parameter acquisition steps: Obtain the return oil temperature Tk, high pressure Hp, and low pressure Lp;

[0017] Data processing steps: Calculate the compressor's compression ratio Px based on the high pressure Hp and low pressure Lp;

[0018] The theoretical discharge temperature Tp' of the compressor is calculated based on the preset relationship between the low pressure Lp, compression ratio Px, oil return temperature Tka and theoretical discharge temperature Tp'.

[0019] Update step: Use the data processing results from the data processing step as the compressor's exhaust temperature.

[0020] According to this technical solution, when the low-pressure is high, the corresponding return gas temperature and exhaust temperature are also high. Conversely, when the low-pressure is low, liquid refrigerant may be drawn into the compressor. A higher compression ratio results in a higher exhaust temperature. Specifically, if the low-pressure remains constant while the high-pressure increases, the compression ratio increases, leading to a rise in exhaust temperature. Conversely, if the exhaust pressure remains constant while the suction pressure decreases, the compression ratio increases, also leading to a rise in exhaust temperature. Calculating the theoretical exhaust temperature by combining the compression ratio with the calculation of the compression ratio reduces the bias of a single low-pressure or high-pressure factor on the exhaust temperature, improving the accuracy of the theoretical exhaust temperature calculation. Furthermore, a high return oil temperature also results in a high compressor exhaust temperature. By comprehensively considering the influence of the low-pressure gas at the compressor suction port on the exhaust temperature, the compression ratio (related to the compressor's exhaust and suction pressures) on the exhaust temperature, and the compressor's return oil temperature on the exhaust temperature, the theoretical exhaust temperature is calculated. This improves the accuracy of the theoretical exhaust temperature calculation results, thereby facilitating the normal operation and control of the air conditioning system, enhancing its energy efficiency and operational stability, and enabling timely exhaust protection in case of exhaust failure, thus ensuring the compressor's service life.

[0021] In the optional technical solutions of the present invention,

[0022] Theoretical exhaust temperature Tp' = A·Lp + B·Tk + C·Px + D;

[0023] Where Px = (Lp + 0.1) / (Hp + 0.1), and A, B, C, and D are constants.

[0024] According to this technical solution, by making the air conditioning system run normally and fitting the collected compression ratio, low pressure, and return oil temperature with the actual exhaust temperature of the compressor, it is found that when the theoretical exhaust temperature has a linear relationship with the low pressure, compression ratio, and oil temperature, the theoretical exhaust temperature is close to the actual exhaust temperature. The operation of the air conditioning system can be adjusted based on the theoretical exhaust temperature.

[0025] In the optional technical solutions of the present invention, 0 < A < 2, 0.8 < B < 2; 0 < C < 5; 0 < D < 25, and D is related to the outdoor ambient temperature.

[0026] According to this technical solution, by controlling the values ​​of A, B, C, and D within the above-mentioned range, and by determining the value of D in conjunction with the outdoor ambient temperature, the accuracy of the theoretical exhaust temperature calculation results can be improved.

[0027] In an optional technical solution of the present invention, the air conditioning system further includes: a return air temperature sensor for detecting the return air temperature Ts of the air conditioning system; the method for determining the exhaust temperature further includes performing the following steps after the frequency determination step and before the parameter acquisition step:

[0028] First reading step: Read the return gas temperature Ts and low-pressure Lp;

[0029] Search steps: Based on the return gas temperature Ts and the low-pressure Lp, find the refrigerant saturation temperature Ta corresponding to the low-pressure Lp;

[0030] First calculation step: The difference between the return gas temperature Ts and the refrigerant saturation temperature Ta is denoted as Ts-Ta;

[0031] First comparison step: Compare Ts-Ta with the first preset value;

[0032] Judgment Step: Based on the comparison results of the first comparison step, determine whether to execute the parameter acquisition step.

[0033] According to this technical solution, by comparing Ts-Ta with the first preset value, and determining whether to execute the parameter acquisition step and subsequent data processing and update steps based on the comparison result, it can be ensured that the return gas of the compressor has a certain degree of superheat when executing subsequent parameter acquisition steps, preventing the compressor from being liquid-sluged, which is conducive to improving the stability of the air conditioning system and ensuring the service life of the compressor.

[0034] In an optional technical solution of the present invention, in the judgment step, if Ts-Ta is not less than the first preset value, the parameter acquisition step is executed; if Ts-Ta is less than the first preset value, the process returns to the reading step.

[0035] According to this technical solution, when Ts-Ta ≥ the first preset value, it indicates that the return gas pipeline has a certain degree of superheat. At this time, executing the parameter acquisition step and subsequent update steps can prevent the compressor from being liquid-slugged and improve the reliability of compressor operation. When Ts-Ta < the first preset value, it returns to the first reading and acquisition step to maintain the current operating state of the air conditioning system and prevent the operational reliability of the air conditioning system from being affected by the marginalization of operating parameters.

[0036] In an optional technical solution of the present invention, the air conditioning system further includes:

[0037] The oil return port is located on the compressor.

[0038] The oil return line connects the oil return port to the outlet of the second heat exchanger, and the oil temperature sensor is located in the oil return line.

[0039] The oil separator has its inlet connected to the compressor outlet and its outlet connected to the oil return line.

[0040] According to this technical solution, the lubricating oil after the refrigerant at the compressor outlet is separated by the oil separator returns to the compressor via the return oil pipeline. The oil temperature sensor is installed in the return oil pipeline, and the measured oil temperature is the oil temperature discharged from the compressor exhaust port, which improves the accuracy of the theoretical exhaust temperature calculation results.

[0041] In an optional technical solution of the present invention, the air conditioning system further includes an exhaust temperature sensor for detecting the actual exhaust temperature Tp of the compressor; the method for determining the exhaust temperature further includes performing the following steps before executing the frequency determination step:

[0042] Obtain the actual exhaust temperature Tp;

[0043] Determine whether the actual exhaust temperature Tp is within the fault temperature range. If the actual exhaust temperature Tp is within the fault temperature range, output an exhaust temperature sensor fault and execute the parameter acquisition step; if the actual exhaust temperature Tp is not within the fault temperature range, execute the frequency acquisition step.

[0044] According to this technical solution, by preset a fault temperature range for the exhaust temperature and determining whether the actual exhaust temperature falls within this range, it can be determined whether the exhaust temperature sensor is faulty. When the exhaust temperature sensor fails, an update step is executed, and the operation of the air conditioning system is regulated using the theoretical exhaust temperature, ensuring the reliability of the air conditioning system. Furthermore, compared to existing technologies where the compressor shuts down when the exhaust temperature sensor fails, this theoretical exhaust temperature setting allows the air conditioning system to operate in an emergency, preventing a complete shutdown. This ensures both the energy efficiency of the air conditioning system and the effectiveness of exhaust protection, avoiding problems such as compressor and system component burnout due to inaccurate exhaust temperature detection.

[0045] In the optional technical solutions of the present invention,

[0046] The process includes the following steps after the frequency determination step and before the reading step:

[0047] Second reading step: When the operating frequency is greater than the specified frequency, read the actual exhaust temperature and return oil temperature; Second calculation step: Calculate the difference between the return oil temperature Tk and the actual exhaust temperature Tp, and record it as Tk-Tp;

[0048] Second comparison step: Compare Tk-Tp with the second preset value;

[0049] Output steps: Based on the comparison results of the second comparison step, determine whether to output an exhaust temperature sensor fault.

[0050] According to this technical solution, the lubricating oil in the refrigerant at the compressor outlet takes a relatively short time to return to the compressor after being separated by the oil separator. By comparing the difference between the return oil temperature and the actual discharge temperature, it is possible to determine whether the discharge temperature detected by the discharge temperature sensor is faulty. This solution has the advantages of convenient operation, high accuracy, and ease of implementation. In addition, by combining the compressor's operating frequency to determine whether to calculate Tk-Tp, it is possible to ensure that the compressor obtains the corresponding return oil temperature and actual discharge temperature during stable operation, thereby improving the accuracy of the Tk-Tp calculation results.

[0051] In an optional technical solution of the present invention, in the output step, if Tk-Tp ≥ the second preset value, then an exhaust temperature sensor fault is output and a reading step is executed; if Tk-Tp < the second preset value, then the exhaust temperature determination process ends.

[0052] According to this technical solution, if Tk-Tp ≥ the second preset value, it indicates a large difference between the return oil temperature and the exhaust temperature, suggesting a fault in the exhaust temperature sensor. In the event of an exhaust temperature sensor failure, an update step is executed, utilizing the theoretical exhaust temperature to regulate the operation of the air conditioning system and ensure its reliability. If Tk-Tp < the second preset value, it indicates that the exhaust temperature detected by the oil temperature sensor is within the allowable temperature difference, meaning the exhaust temperature sensor is not faulty, and the judgment process can be terminated.

[0053] The present invention also provides an air conditioning system that performs the above-described method for determining the exhaust temperature of the air conditioning system. Attached Figure Description

[0054] Figure 1 This is a schematic diagram of the air conditioning system in an embodiment of the present invention.

[0055] Figure 2 This is a flowchart illustrating the method for determining the exhaust temperature of an air conditioning system according to an embodiment of the present invention.

[0056] Figure 3 This is a schematic diagram of the air conditioning system in an embodiment of the present invention.

[0057] Figure 4 This is a flowchart illustrating the method for determining the exhaust temperature of an air conditioning system in an embodiment of the present invention.

[0058] Figure label:

[0059] Compressor 11; First compressor 111; Second compressor 112; Four-way valve 12; First heat exchanger 13; Throttling element 14; Second heat exchanger 15; Oil separator 16; First oil separator 161; Second oil separator 162; Gas-liquid separator 17; First gas-liquid separator 171; Second gas-liquid separator 172; Exhaust temperature sensor 2; First exhaust temperature sensor 21; Second exhaust temperature sensor 22; High pressure sensor 31; Low pressure sensor 32; Return gas temperature sensor 4; Oil temperature sensor 5; First oil temperature sensor 51; Second oil temperature sensor 52; Return oil line 6; First return oil line 61; Second return oil line 62. Detailed Implementation

[0060] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. 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.

[0061] This invention provides a method for determining the exhaust temperature of an air conditioning system, such as... Figure 1 As shown, the air conditioning system includes a compressor 11, a four-way valve 12, a first heat exchanger 13, a throttling element 14, and a second heat exchanger 15 connected in sequence to form a refrigerant cycle. The compressor 11 has an oil return port. The air conditioning system also includes:

[0062] Exhaust temperature sensor 2 is used to detect the actual exhaust temperature Tp of compressor 11;

[0063] High pressure sensor 31 is used to detect the high pressure Hp of the air conditioning system, i.e., the discharge pressure of compressor 11;

[0064] The low-pressure sensor 32 is used to detect the low-pressure Lp of the air conditioning system, that is, the return gas pressure of the compressor 11.

[0065] Return air temperature sensor 4 is used to detect the return air temperature Ts of the air conditioning system;

[0066] Oil temperature sensor 5 is used to detect the return oil temperature Tk of compressor 11;

[0067] The oil return line 6 connects the oil return port to the outlet of the second heat exchanger 15, and the oil temperature sensor 5 is located in the oil return line 6.

[0068] The oil separator 16 has its inlet connected to the outlet of the compressor 11 and its outlet connected to the return oil line 6.

[0069] The outlet of the gas-liquid separator is connected to the return gas port of the compressor 11.

[0070] like Figure 2 As shown, the methods for determining exhaust temperature include:

[0071] When the air conditioning system is powered on for the first time, the actual exhaust temperature Tp is obtained;

[0072] Determine whether the actual exhaust temperature Tp is within the fault temperature range;

[0073] If the actual exhaust temperature Tp is within the fault temperature range, then the exhaust temperature sensor 2 is faulty and the following steps are executed:

[0074] First reading step: Read the return gas temperature Ts and low-pressure Lp;

[0075] Search steps: Based on the return gas temperature Ts and the low-pressure Lp, find the refrigerant saturation temperature Ta corresponding to the low-pressure Lp;

[0076] First calculation step: Calculate the difference between the return gas temperature Ts and the refrigerant saturation temperature Ta, denoted as Ts-Ta;

[0077] First comparison step: Compare Ts-Ta with the first preset value;

[0078] Judgment Step: Based on the comparison results of the first comparison step, determine whether to execute the parameter acquisition step: acquire the return oil temperature Tk, high pressure Hp, and low pressure Lp;

[0079] Furthermore, after the parameter acquisition step, the system also includes a data processing step, which calculates the compression ratio Px of the compressor 11 based on the high pressure Hp and the low pressure Lp.

[0080] Based on the preset relationship between low pressure Lp, compression ratio Px, oil return temperature Tk and theoretical discharge temperature Tp', the theoretical discharge temperature Tp' of compressor 11 is calculated.

[0081] Update step: Use the data processing result of the data processing step as the exhaust temperature of compressor 11.

[0082] In this embodiment, when an exhaust temperature fault occurs, by comparing Ts-Ta with a first preset value and determining whether to execute the parameter acquisition step and subsequent data processing and update steps based on the comparison result, liquid slugging of the compressor 11 can be prevented, which is beneficial to improving the stability of the air conditioning system and ensuring the service life of the compressor 11. Specifically, if Ts-Ta ≥ the first preset value, it indicates that the return gas of the compressor 11 has a certain degree of superheat. At this time, executing the parameter acquisition steps will not cause liquid slugging of the compressor 11, thus improving the reliability of the compressor 11's operation. If Ts-Ta < the first preset value, the process returns to the parameter acquisition step, maintaining the current operating state of the air conditioning system and preventing the marginalization of operating parameters from affecting the operational reliability of the air conditioning system.

[0083] Furthermore, in the air conditioning system, when the low-pressure is high, the corresponding return gas temperature and discharge temperature of the compressor 11 are also high. Conversely, when the low-pressure is low, liquid refrigerant may be drawn into the compressor 11. Additionally, a higher compression ratio results in a higher discharge temperature. If the low-pressure remains constant while the high-pressure increases, the compression ratio increases, leading to a rise in discharge temperature. Conversely, if the discharge pressure remains constant while the suction pressure decreases, the compression ratio increases, also leading to a rise in discharge temperature. This embodiment combines the calculation of the theoretical discharge temperature with the compression ratio, reducing the bias of the influence of a single low-pressure or high-pressure on the discharge temperature and improving the accuracy of the theoretical discharge temperature Tp' calculation. Furthermore, a high oil return temperature Tk also results in a high discharge temperature for the compressor 11. It should be noted that the discharge temperature described in this article usually refers to the actual discharge temperature Tp. By comprehensively considering the influence of the low air pressure at the suction port of compressor 11 on the exhaust temperature, the influence of the compression ratio (related to the exhaust pressure and suction pressure of compressor 11) on the exhaust temperature, and the influence of the oil return temperature Tk of compressor 11 on the exhaust temperature, the theoretical exhaust temperature Tp' is calculated. This improves the accuracy of the theoretical exhaust temperature Tp' calculation results, which is beneficial to the normal control and operation of the air conditioning system, improves the energy efficiency and operational stability of the air conditioning system, and enables timely exhaust protection in the event of an exhaust failure, thus ensuring the service life of compressor 11.

[0084] On the other hand, if the actual exhaust temperature Tp is not within the fault temperature range, then execute:

[0085] Frequency acquisition steps: Obtain the operating frequency of compressor 11;

[0086] Frequency determination steps: Determine whether the operating frequency is greater than the specified frequency;

[0087] Second reading step: When the operating frequency is greater than the specified frequency, read the actual exhaust temperature Tp and return oil temperature Tk;

[0088] Second calculation step: Calculate the difference between the return oil temperature Tk and the actual exhaust temperature Tp, denoted as Tk-Tp;

[0089] Second comparison step: Compare Tk-Tp with the second preset value;

[0090] Output steps: Based on the comparison results of the second comparison step, determine whether to output a fault in exhaust temperature sensor 2.

[0091] In this embodiment, by presetting a fault temperature range for the exhaust temperature and determining whether the actual exhaust temperature Tp falls within this range, it can be determined whether the exhaust temperature sensor 2 is faulty. To improve the accuracy of determining whether the exhaust temperature is faulty, if the actual exhaust temperature Tp is not within the fault temperature range, it is further determined whether the operating frequency of the compressor 11 is greater than a specified frequency. When the compressor 11 is operating normally, the difference between the oil return temperature Tk and the actual exhaust temperature Tp is compared. Since the lubricating oil in the refrigerant at the compressor 11 outlet takes a relatively short time to return to the compressor 11 after being separated by the oil separator 16, the difference between the oil return temperature Tk and the actual exhaust temperature Tp is used to determine whether the actual exhaust temperature Tp detected by the exhaust temperature sensor 2 is faulty. This method has the advantages of convenient operation, high accuracy, and ease of implementation.

[0092] In a preferred embodiment of the present invention, in the output step, if Tk-Tp ≥ a second preset value, then an exhaust temperature sensor 2 fault is output; if Tk-Tp < the second preset value, then the exhaust temperature determination process ends. Specifically, if Tk-Tp ≥ the second preset value, it indicates that the difference between the return oil temperature Tk and the actual exhaust temperature Tp is large, and the exhaust temperature sensor 2 is faulty. When determining that the exhaust temperature sensor 2 is faulty, one or more of the above-described steps—the first reading step, the search step, the first calculation step, the first comparison step, the judgment step, the parameter acquisition step, the data processing step, and the update step—are repeated, and will not be elaborated further here.

[0093] If Tk-Tp < the second preset value, it indicates that the oil temperature sensor 5 detects the return oil temperature Tk and the actual exhaust temperature Tp within the allowable temperature difference, and the exhaust temperature sensor 2 is not faulty. Therefore, the judgment process can be terminated.

[0094] In a preferred embodiment of the present invention, by ensuring the air conditioning system operates normally (the exhaust temperature sensor 2 can normally collect the actual exhaust temperature Tp), and by fitting the collected compression ratio Px, low-pressure Lp, and oil return temperature Tk with the actual exhaust temperature Tp of the compressor 11, a preset relationship between the theoretical exhaust temperature Tp' and the compression ratio Px, low-pressure Lp, and oil return temperature Tk is obtained: Tp'=A·Lp+B·Tk+C·Px+D; where Px=(Lp+0.1) / (Hp+0.1), and A, B, C, and D are constants. That is, when the theoretical exhaust temperature has a linear relationship with the low-pressure, compression ratio, and oil temperature, the theoretical exhaust temperature is close to the actual exhaust temperature. In the event of a failure of the exhaust temperature sensor 2, the operation of the air conditioning system can be adjusted based on the theoretical exhaust temperature, ensuring the reliability of the air conditioning system operation.

[0095] In a preferred embodiment of the present invention, 0 < A < 2, 0.8 < B < 2; 0 < C < 5; 0 < D < 25, and D is associated with the outdoor ambient temperature T4. By controlling the values ​​of A, B, C, and D within the above ranges, and by determining the value of D in conjunction with the outdoor ambient temperature T4, the accuracy of the theoretical exhaust temperature calculation results can be improved.

[0096] Specifically, the value ranges of parameters A, B, C, and D are as follows:

[0097]

[0098] In this embodiment, by combining the air conditioner's operating mode and the outdoor ambient temperature T4 to determine the coefficients in the theoretical exhaust temperature calculation formula, the accuracy of the exhaust temperature calculation for the air conditioning system under different operating conditions and different outdoor ambient temperatures can be improved.

[0099] The following example illustrates the process of determining the exhaust temperature in this embodiment.

[0100] This embodiment provides a method for determining the exhaust temperature of an air conditioning system, such as... Figure 3 As shown, the air conditioning system includes a first compressor 111, a second compressor 112, a four-way valve 12, a first heat exchanger 13, a throttling element 14, and a second heat exchanger 15. The refrigerant from the outlets of the first compressor 111 and the second compressor 112 mixes and sequentially passes through the first heat exchanger 13, the throttling element 14, and the second heat exchanger 15 before being diverted back to the first compressor 111 and the second compressor 112. The first compressor 111 has a first oil return port, and the second compressor 112 has a second oil return port. The air conditioning system also includes:

[0101] The first exhaust temperature sensor 21 is used to detect the exhaust temperature Tpa of the first compressor 111;

[0102] The second exhaust temperature sensor 22 is used to detect the exhaust temperature Tpb of the second compressor 112.

[0103] The first oil temperature sensor 51 is used to detect the return oil temperature Tka of the first compressor 111;

[0104] The second oil temperature sensor 52 is used to detect the return oil temperature Tkb of the second compressor 112.

[0105] High-pressure sensor 31 is used to detect the high-pressure Hp of the air conditioning system;

[0106] Low-pressure sensor 32 is used to detect the low-pressure Lp of the air conditioning system.

[0107] Return air temperature sensor 4 is used to detect the return air temperature Ts of the air conditioning system.

[0108] The first return oil line 61 connects the first return oil port to the outlet of the second heat exchanger 15, and the first oil temperature sensor 51 is located in the first return oil line 61.

[0109] The second return oil line 62 connects the second return oil port to the outlet of the second heat exchanger 15, and the second oil temperature sensor 52 is located in the second return oil line 62.

[0110] The first oil separator 161 has its inlet connected to the outlet of the first compressor 111 and its outlet connected to the first return oil pipeline 61.

[0111] The inlet of the second oil separator 162 is connected to the outlet of the second compressor 112, and the outlet is connected to the second return oil pipeline 62.

[0112] The inlet of the first gas-liquid separator 171 is connected to one outlet of the four-way valve 12, and the outlet is connected to the return gas port of the first compressor 111.

[0113] The inlet of the second gas-liquid separator 172 is connected to one outlet of the four-way valve 12, and the outlet is connected to the return port of the second compressor 112. In this embodiment, the inlets of the first gas-liquid separator 171 and the second gas-liquid separator 172 are connected to the same outlet of the four-way valve 12.

[0114] like Figure 4 As shown, the method for determining the exhaust temperature includes the following steps:

[0115] Upon initial power-on of the unit, the analog electrical signals AD1 and AD2 corresponding to the first exhaust temperature sensor 21 and the second exhaust temperature sensor 22 are read. (For brevity purposes...) Figure 4 In the flowchart, the first exhaust temperature / first exhaust temperature sensor is represented by Tpa, and the second exhaust temperature / second exhaust temperature sensor is represented by Tpb.

[0116] Step S2: Simultaneously determine condition one (AD1 b, i.e., whether the exhaust temperature Tpa is within the fault temperature range) and condition two (AD2 b, i.e., whether the exhaust temperature Tpb is within the fault temperature range). When condition one is met, the host records a Tpa fault and proceeds to step S8; when it is not met, proceed to step S3. When condition two is met, the host records a Tpb fault and proceeds to step S8; when it is not met, proceed to step S3. Here, a and b are constants determined by the characteristics of the thermistor used; the value of a ranges from 0 to 100, and 12 is selected here; the value of b ranges from 1000 to 2000, and 1000 is selected here.

[0117] Step S3: Read the operating frequency Fa of the first compressor 111 and the operating frequency Fb of the second compressor 112.

[0118] Step S4: Determine whether the operating frequency is within the specified frequency range (0≤Fb<c) and 0≤Fa<c). If it is true, return to step S3; if it is not true, proceed to step S5. Here, c is a constant, ranging from 30 to 60, and is set to 45 here.

[0119] Step S5: Read Tpa, Tpb, Tka, and Tkb. When Fa > c and 0 ≤ Fb < c, calculate Tka - Tpa; when Fb > c and 0 ≤ Fa < c, calculate Tb - Tpb; when Fa > c and Fb > c, calculate Tka - Tpa and Tkb - Tpb simultaneously; proceed to step S6.

[0120] Step S6: Determine if the conditions Tka-Tpa < d and Tkb-Tpb < e are met, proceed to step S10 if they are met, and proceed to step S7 if they are not met.

[0121] Step S7: When Tka-Tpa≥d, send the Tpa fault code to the host record; when Tkb-Tpb≥e, send the Tpb fault code to the host record; when Tka-Tpa≥d and Tkb-Tpb≥e, send the Tpa and Tpb fault codes to the host record; proceed to step S8. Wherein, d and e are constants, with values ​​ranging from 8 to 15, and here the value is 10.

[0122] Step S8: Read the return gas temperature Ts and low pressure Lp, look up the table to obtain the refrigerant saturation temperature Ta corresponding to the low pressure Lp, and proceed to step S9.

[0123] Step S9: Determine if Ts-Ta≥f. If Ts-Ta≥f is true, proceed to step S10; if Ts-Ta≥f is false, return to step S8. (f is a constant, ranging from 0 to 10, and here it is 3.)

[0124] Step S10: Read Tka, Tkb, high pressure Hp, and low pressure Lp, calculate the compression ratio Px = (Lp + 0.1) / (Hp + 0.1), calculate Tpa' and Tpb' according to the formulas Tpa' = A·Lp + B·Tka + C·Px + D and Tpb' = A·Lp + B·Tkb + C·Px + D, and update Tpa and Tpb.

[0125] In this embodiment, the host can be an integrated circuit chip with signal processing capabilities. The host can be a general-purpose processor, including a Central Processing Unit (CPU), or a microcontroller, microcontroller unit (MCU), complex programmable logic device (CPLD), field-programmable gate array (FPGA), application-specific integrated circuit (ASIC), embedded ARM, etc. The host can implement or execute the methods, steps, and logic block diagrams disclosed in this embodiment. The host can be connected to various temperature and pressure sensors, receive signals detected by the temperature and pressure sensors, and process them into computable data. All judgment conditions and preset parameters in this embodiment can be stored in the host.

[0126] It should be noted that although this embodiment illustrates a method for determining one or two exhaust temperatures, those skilled in the art can apply the above principles to determine three or more exhaust temperatures, and this embodiment does not limit this. Furthermore, the values ​​illustrated in this embodiment are preferred values. For different air conditioning systems, those skilled in the art can adjust these values ​​according to the actual operating conditions and equipment parameters of the air conditioning system, and are not limited to these values.

[0127] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for determining the exhaust temperature of an air conditioning system, the air conditioning system comprising a compressor, a four-way valve, a first heat exchanger, a throttling element, and a second heat exchanger connected in sequence to form a refrigerant cycle, and further comprising: An oil temperature sensor is used to detect the return oil temperature Tk of the compressor; A high-pressure sensor is used to detect the high-pressure Hp of the air conditioning system; A low-pressure sensor is used to detect the low-pressure Lp of the air conditioning system; The method for determining the exhaust temperature is characterized by comprising: Frequency acquisition step: Obtain the operating frequency of the compressor: Frequency determination step: Determine whether the operating frequency is less than the specified frequency; if the operating frequency is not less than the specified frequency, then execute the parameter acquisition step; if the operating frequency is less than the specified frequency, then return to the frequency acquisition step. Parameter acquisition steps: Acquire the return oil temperature Tk, the high pressure Hp, and the low pressure Lp; Data processing steps: Calculate the compression ratio Px of the compressor based on the high pressure Hp and the low pressure Lp; Based on the preset relationship between the low-pressure Lp, the compression ratio Px, the oil return temperature Tk, and the theoretical discharge temperature Tp', the theoretical discharge temperature Tp' of the compressor is calculated, where Tp' = A. Lp+B Tk+C Px+D, where Px=(Lp+0.1) / (Hp+0.1), A, B, C, and D are constants, and D is related to the outdoor ambient temperature; Update step: Use the data processing result of the data processing step as the exhaust temperature of the compressor; The air conditioning system further includes: a return air temperature sensor for detecting the return air temperature Ts of the air conditioning system; the method for determining the exhaust temperature further includes, after performing the frequency determination step and before performing the parameter acquisition step, performing the following steps: Reading steps: Read the return gas temperature Ts and the low-pressure Lp; Search steps: Based on the return gas temperature Ts and the low pressure Lp, find the refrigerant saturation temperature Ta corresponding to the low pressure Lp; First calculation step: Calculate the difference between the return gas temperature Ts and the refrigerant saturation temperature Ta, denoted as Ts-Ta; First comparison step: Compare Ts-Ta with the first preset value; Judgment step: Based on the comparison result of the first comparison step, determine whether to execute the parameter acquisition step, including: if Ts-Ta is not less than the first preset value, then execute the parameter acquisition step; if Ts-Ta is less than the first preset value, then return to the reading step.

2. The method for determining the exhaust temperature of an air conditioning system according to claim 1, characterized in that, 0<A<2, 0.8<B<2; 0<C<5; 0<D<25.

3. The method for determining the exhaust temperature of an air conditioning system according to claim 1, characterized in that, The air conditioning system also includes: An oil return port is located on the compressor. A return oil pipeline connects the return oil port to the outlet of the second heat exchanger, and the oil temperature sensor is located in the return oil pipeline; The oil separator has its inlet connected to the outlet of the compressor and its outlet connected to the oil return line.

4. The method for determining the exhaust temperature of an air conditioning system according to claim 3, characterized in that, The air conditioning system further includes: an exhaust temperature sensor for detecting the actual exhaust temperature Tp of the compressor; the method for determining the exhaust temperature further includes, before performing the frequency determination step, performing the following steps: obtaining the actual exhaust temperature Tp; Determine whether the actual exhaust temperature Tp is within the fault temperature range. If the actual exhaust temperature Tp is within the fault temperature range, output a fault for the exhaust temperature sensor and execute the parameter acquisition step. If the actual exhaust temperature Tp is not within the fault temperature range, execute the frequency acquisition step.

5. The method for determining the exhaust temperature of an air conditioning system according to claim 4, characterized in that, The process includes the following steps after performing the frequency determination step and before performing the reading step: Second reading step: If the operating frequency is greater than the specified frequency, read the actual exhaust temperature Tp and the return oil temperature Tk; Second calculation step: Calculate the difference between the oil return temperature Tk and the actual exhaust temperature Tp, and record it as Tk-Tp; Second comparison step: Compare Tk-Tp with the second preset value; Output step: Based on the comparison result of the second comparison step, determine whether to output that the exhaust temperature sensor is faulty.

6. The method for determining the exhaust temperature of an air conditioning system according to claim 5, characterized in that, In the output step, if Tk-Tp ≥ the second preset value, then the exhaust temperature sensor is faulty and the reading step is executed; if Tk-Tp < the second preset value, then the exhaust temperature determination process ends.

7. An air conditioning system, characterized in that, The method for determining the exhaust temperature of the air conditioning system according to any one of claims 1 to 6.

Images