Air conditioning system

Abstract

The application provides an 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 circulation, and further comprising an exhaust temperature sensor, a high pressure sensor, a low pressure sensor, a return air temperature sensor, an ambient temperature sensor and a control device configured to perform the following steps: obtaining a high pressure saturation temperature Tc, a low pressure saturation temperature Te, a high pressure Hp, a low pressure Lp and a return air temperature Ts of the air conditioning system; obtaining an outdoor ambient temperature and determining corresponding specified ambient parameters according to the outdoor ambient temperature; calculating a first difference and a second difference; comparing the first difference with a corresponding first preset value and comparing the second difference with a corresponding second preset value; and determining whether the oil temperature of the compressor is qualified according to the comparison results of the comparison steps. When the oil temperature sensor fails, the application determines whether the oil temperature of the compressor is faulty through the exhaust temperature related parameters, thereby ensuring the reliable operation of the compressor.

Description

Technical Field

[0001] This invention relates to the field of air conditioning, specifically to an air conditioning system capable of automatically determining oil temperature. Background Technology

[0002] Existing multi-split air conditioning products typically include an oil temperature detection device to monitor the compressor's oil return temperature. When the detected oil temperature is below standard, the air conditioning system can implement effective protective measures to ensure the compressor does not suffer from insufficient lubrication due to low oil temperature or oil shortage, leading to wear, seizure, or burnout. However, if the compressor oil temperature detection device malfunctions (open circuit, short circuit, or detection drift), it cannot obtain the true compressor oil temperature, potentially resulting in the following: ① False alarms of low compressor oil temperature, causing the air conditioning system to malfunction. ② Inability to detect the true compressor oil temperature, failing to provide timely protection when low oil temperature or oil shortage occurs, resulting in insufficient compressor lubrication and serious quality problems such as compressor wear, seizure, or burnout. This negatively impacts user experience and increases after-sales maintenance costs. Summary of the Invention

[0003] To address the above problems, this invention provides an air conditioning system that, when the oil temperature detection device malfunctions, can determine whether the compressor oil temperature is qualified by combining the environmental parameters corresponding to the outdoor ambient temperature, the difference between the exhaust temperature Tp, the high-pressure saturation temperature Tc and the environmental parameter g corresponding to the specified outdoor ambient temperature, and the difference between the return gas temperature Ts and the low-pressure saturation temperature Te. This improves the accuracy of oil temperature judgment and ensures stable and reliable operation of the compressor.

[0004] This invention provides an 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: Exhaust temperature sensor, used to detect the compressor's exhaust temperature Tp; High-pressure sensor 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 an air conditioning system. Return air temperature sensor, used to detect the return air temperature Ts of the air conditioning system; An ambient temperature sensor is used to detect the outdoor ambient temperature. The control device is configured to perform an oil temperature determination step; the oil temperature determination step includes: Parameter acquisition steps: Obtain the high-pressure saturation temperature Tc, low-pressure saturation temperature Te, high-pressure pressure Hp, low-pressure pressure Lp, and return gas temperature Ts of the air conditioning system; Environmental parameter determination steps: Obtain the outdoor ambient temperature and determine the corresponding specified environmental parameters based on the outdoor ambient temperature; Calculation steps: Calculate the first difference and the second difference. The first difference is the difference between the exhaust temperature Tp, the high-pressure saturation temperature Tc, and the specified environmental parameter g. The second difference is the difference between the return gas temperature Ts and the low-pressure saturation temperature Te. Comparison steps: Compare the first difference with the corresponding first preset value, and compare the second difference with the corresponding second preset value; Judgment steps: Determine whether the compressor oil temperature is qualified based on the comparison results of the comparison steps.

[0005] According to this technical solution, the first difference is the difference between the compressor's exhaust superheat and the specified environmental parameters. By combining this with the environmental parameters corresponding to the outdoor ambient temperature, the compressor's exhaust condition is determined, reducing the impact of the outdoor ambient temperature on the accuracy of the exhaust superheat measurement results and improving the accuracy of the compressor's exhaust condition assessment. The second difference is the compressor's intake superheat. By comparing the intake superheat with a second preset value, it is determined whether the intake superheat is within a suitable superheat range, thus obtaining the compressor's intake condition assessment. By simultaneously combining the compressor's exhaust and intake performance, the accuracy of oil temperature assessment is improved, which is beneficial for timely protection in case of oil shortage, thereby improving the compressor's service life and the safety and reliability of its operation.

[0006] In the optional technical solution of the present invention, if the outdoor ambient temperature is less than or equal to a first threshold, then the environmental parameter is defined as a first constant; If the second threshold ≤ outdoor ambient temperature ≤ the third threshold, then the environmental parameter g is defined as the second constant; If the fourth threshold ≤ outdoor ambient temperature ≤ the fifth threshold, then the environmental parameter g is defined as the third constant; If the sixth threshold ≤ outdoor ambient temperature ≤ the seventh threshold, then the environmental parameter g is defined as the fourth constant; If the eighth threshold ≤ outdoor ambient temperature ≤ the ninth threshold, then the environmental parameter g is defined as the fifth constant; If the tenth threshold ≤ outdoor ambient temperature ≤ eleventh threshold, then the environmental parameter g is defined as the sixth constant; where, The first threshold, second threshold, third threshold, fourth threshold, fifth threshold, sixth threshold, seventh threshold, eighth threshold, ninth threshold, tenth threshold, and eleventh threshold increase sequentially; the first constant ≥ the second constant > the third constant > the fourth constant > the fifth constant ≥ the sixth constant.

[0007] According to this technical solution, dividing the outdoor ambient temperature into different temperature ranges and assigning different environmental parameters to each range helps improve the accuracy of oil temperature determination. Specifically, as the outdoor ambient temperature increases, its impact on the compressor's discharge performance weakens; therefore, the value of the environmental parameter g is specified to decrease.

[0008] In the optional technical solution of the present invention, the range of environmental parameters is specified as 0-10.

[0009] According to this technical solution, by reasonably setting the range of values ​​for specified environmental parameters, the accuracy of oil temperature judgment can be improved, which is conducive to timely corresponding measures when oil shortage occurs, thereby improving the safety and stability of compressor operation and extending the service life of the compressor.

[0010] In the optional technical solution of the present invention, when the first difference is <h and lasts for a second duration; and when the second difference is <d, the oil temperature Tk is determined to be unqualified and the compressor is short of oil. When i ≤ the first difference < j, and this continues for the third duration; and when the second difference ≥ d, the current oil temperature Tk determination result is maintained. When the first difference is ≥ k and lasts for four consecutive durations; and when the second difference is ≥ d, the oil temperature Tk is deemed to be qualified; where d, h, i, j, and k are constants, and h, i, j, and k increase sequentially.

[0011] According to the technical solution, when the first difference is less than h and lasts for a second duration, it indicates that the difference between the exhaust temperature and the refrigerant high-pressure saturation temperature and the specified environmental parameters is small, and the compressor may be short of oil.

[0012] When i ≤ the first difference < j and this condition persists for the third time period, it indicates that the difference between the exhaust temperature and the refrigerant high-pressure saturation temperature and the specified environmental parameters has not been identified as oil shortage within the third time period, and the compressor's operating state is stable. Maintaining the previous oil temperature determination result indicates that the difference between the exhaust temperature and the refrigerant high-pressure saturation temperature and the specified environmental parameters has not been identified as oil shortage within the third time period, and the compressor's operating state is stable. Maintaining the previous oil temperature determination result: If the previous determination result indicated that the compressor was oil-short, an oil return procedure is executed to raise the compressor's oil temperature; if the previous determination result indicated that the compressor was not oil-short, the oil return procedure is not executed, and the current operating state is maintained.

[0013] When the first difference is ≥k and persists for four consecutive time periods, it indicates that the difference between the exhaust temperature and the refrigerant high-pressure saturation temperature and the specified environmental parameters is relatively high. The compressor is within the normal operating range of exhaust superheat and is not short of oil. By dividing the first difference into three different ranges, the accuracy of oil temperature judgment is improved. When the first difference is within the range i~j, the current oil temperature judgment result is maintained, and the operation of the air conditioning system is controlled based on the current oil temperature judgment result, thus improving the stability of the air conditioning system operation.

[0014] Furthermore, when the second difference is ≥ d, it indicates that the return gas temperature is relatively high, meaning the oil temperature inside the compressor is within the normal range. Conversely, when the second difference is < d, it indicates that the return gas temperature is relatively low, and the compressor may be short of oil. By simultaneously judging the first and second differences, the accuracy of oil temperature judgment is improved, unnecessary execution of the oil return procedure is avoided, and the stable and reliable operation of the air conditioning system is ensured.

[0015] In the optional technical solution of the present invention, the range of the first preset value is 0~15; the range of the second preset value is 0~15.

[0016] According to this technical solution, by reasonably setting the range of the first and second preset values, the accuracy of oil temperature judgment can be improved, which is conducive to timely corresponding measures when oil shortage occurs, thereby improving the safety and stability of compressor operation and extending the service life of the compressor.

[0017] In an optional technical solution of the present invention, the oil temperature determination step further includes: Frequency acquisition steps: Acquire the compressor's operating parameters, including the compressor's operating frequency and operating duration; Judgment steps: Determine whether the operating parameters meet the oil temperature judgment conditions; the oil temperature judgment conditions are: the operating frequency is not less than the specified frequency threshold, and the operating time is not less than the first duration; Control steps: If the operating parameters meet the oil temperature judgment conditions, the control will execute the oil temperature judgment step.

[0018] According to this technical solution, when the compressor's operating parameters meet the oil temperature judgment conditions, the oil temperature judgment step is executed, which can avoid frequent initiation of the oil temperature judgment step, thus helping to ensure the operating efficiency of the air conditioning system and its reliable operation.

[0019] The optional technical solutions of the present invention also include: Oil temperature sensor, used to detect the oil temperature Tk of the compressor; The control device is configured to perform an oil temperature fault detection step before the frequency acquisition step; the oil temperature fault detection step includes: Determine if the oil temperature Tk is within the fault temperature range. If the oil temperature Tk is within the fault temperature range, output an oil temperature sensor fault.

[0020] According to this technical solution, by directly obtaining the temperature detection result of the oil temperature sensor, it is possible to determine whether the temperature detection result falls within the fault temperature range, and thus determine whether the oil temperature sensor is faulty. This method is simple, convenient, and easy to implement.

[0021] In an optional technical solution of the present invention, if the oil temperature Tk is not within the fault temperature range, the control device is configured to execute: Frequency comparison steps: Compare the operating frequency with the specified frequency threshold; Second difference comparison step: Compare the second difference with the second preset value; Data processing steps: Calculate the difference between exhaust temperature Tp and oil temperature Tk, and record it as the third difference; then compare the third difference with the difference threshold. Fault diagnosis steps: Based on the comparison results of the frequency comparison step, the second difference comparison step, and the data processing step, determine whether the oil temperature sensor is faulty.

[0022] According to this technical solution, by combining the compressor's operating frequency, suction superheat, and the range of the third difference, it is possible to determine whether the oil temperature sensor is faulty, which helps to improve the accuracy of oil temperature sensor fault diagnosis.

[0023] In the optional technical solution of the present invention, the fault judgment step further includes: when the operating frequency is greater than a specified frequency threshold, when the second difference is not less than a second preset value and the third difference is greater than the difference threshold, the oil temperature sensor is output as faulty.

[0024] According to this technical solution, when the operating frequency is high and the intake superheat is within a reasonable range, the oil temperature sensor is judged to be faulty based on the comparison result of the third difference and the difference threshold, which helps to improve the accuracy of oil temperature judgment. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the air conditioning system in the first embodiment of the present invention.

[0026] Figure 2 This is a schematic diagram of the operation process of the air conditioning system in the first embodiment of the present invention.

[0027] Figure 3 This is a schematic diagram of the air conditioning system in the second embodiment of the present invention.

[0028] Figure 4 This is a schematic diagram of the operation process of the air conditioning system in the second embodiment of the present invention.

[0029] Figure label: Compressor 11; First compressor 111; Second compressor 112; Four-way valve 12; First heat exchanger 13; Throttling element 14; Second heat exchanger 15; Exhaust temperature sensor 2; First temperature sensor 21; Second 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; 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. Detailed Implementation

[0030] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0031] <First Implementation Method> like Figure 1 As shown, the present invention provides an air conditioning system, including a compressor 11, a four-way valve 12, a first heat exchanger 13 (which may be an indoor heat exchanger or an outdoor heat exchanger), a throttling element 14, and a second heat exchanger 15 (which may be an indoor heat exchanger or an outdoor heat exchanger) connected in sequence to form a refrigerant cycle. The compressor 11 has an exhaust port, an intake port, and an oil return port. The air conditioning system further includes: Exhaust temperature sensor 2 is used to detect the exhaust temperature Tp of compressor 11; High pressure sensor 31 is used to detect the high pressure Hp of the air conditioning system, that is, the discharge pressure of compressor 11; 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. Return air temperature sensor 4 is used to detect the return air temperature Ts of the air conditioning system; An ambient temperature sensor (not shown in the figure) is used to detect the outdoor ambient temperature T4. Oil temperature sensor 5 is used to detect the oil temperature Tk of compressor 11; The oil return line 6 is connected between the oil return port and the outlet of the second heat exchanger 15, and the oil temperature sensor 5 is located in the oil return line 6. The oil separator 16 has its inlet connected to the exhaust port of the compressor 11, and its outlet connected to the oil return port through the oil return pipeline 6. The gas-liquid separator 17 has its inlet connected to one outlet of the four-way valve 12, and its inlet connected to the return port of the compressor 11; and Control device (not shown in the figure), such as Figure 2 As shown, it is configured to perform an oil temperature determination step; the oil temperature determination step includes: Parameter acquisition steps: Obtain the high-pressure saturation temperature Tc, low-pressure saturation temperature Te, high-pressure pressure Hp, low-pressure pressure Lp, and return gas temperature Ts of the air conditioning system; Environmental parameter determination steps: Obtain the outdoor ambient temperature and determine the corresponding specified environmental parameters based on the outdoor ambient temperature; Calculation steps: Calculate the first difference and the second difference. The first difference is the difference between the exhaust temperature Tp, the high-pressure saturation temperature Tc, and the specified environmental parameter g. The second difference is the difference between the return gas temperature Ts and the low-pressure saturation temperature Te. Comparison steps: Compare the first difference with the corresponding first preset value, and compare the second difference with the corresponding second preset value; Judgment steps: Determine whether the oil temperature of compressor 11 is qualified based on the comparison results of the comparison steps.

[0032] Through the above methods, the first difference is the difference between the exhaust superheat of compressor 11 and the specified environmental parameters. By combining the environmental parameters corresponding to the outdoor ambient temperature, the exhaust condition of compressor 11 is judged, reducing the influence of outdoor ambient temperature on the accuracy of the exhaust superheat measurement results and improving the accuracy of judging the exhaust condition of compressor 11. In addition, when oil temperature sensor 5 malfunctions, the oil temperature is determined by the relevant parameters of exhaust temperature, enabling timely protection in case of oil shortage and ensuring reliable operation of the compressor. The second difference is the suction superheat of compressor 11. By comparing the suction superheat with a second preset value, it is determined whether the suction superheat is within a suitable superheat range, thus obtaining the judgment of the suction condition of compressor 11. By simultaneously combining the exhaust and suction performance of compressor 11, the accuracy of oil temperature judgment is improved, which is conducive to timely protection in case of oil shortage, improving the service life of compressor 11 and the safety and reliability of compressor 11 operation.

[0033] In this embodiment, the control device can be an integrated circuit chip with signal processing capabilities. The aforementioned control device 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 control device can implement or execute the methods, steps, and logic block diagrams disclosed in this embodiment. The control device is the host, which can be connected to various temperature and pressure sensors to receive signals detected by the sensors and process them into computable data. Various judgment conditions and preset parameters in this embodiment can be stored in the control device.

[0034] In a preferred embodiment of the present invention, if the outdoor ambient temperature is less than or equal to a first threshold, the environmental parameter is defined as a first constant. If the second threshold ≤ outdoor ambient temperature ≤ the third threshold, then the environmental parameter g is defined as the second constant; If the fourth threshold ≤ outdoor ambient temperature ≤ the fifth threshold, then the environmental parameter g is defined as the third constant; If the sixth threshold ≤ outdoor ambient temperature ≤ the seventh threshold, then the environmental parameter g is defined as the fourth constant; If the eighth threshold ≤ outdoor ambient temperature ≤ the ninth threshold, then the environmental parameter g is defined as the fifth constant; If the tenth threshold ≤ outdoor ambient temperature ≤ eleventh threshold, then the environmental parameter g is defined as the sixth constant; where, The first threshold, second threshold, third threshold, fourth threshold, fifth threshold, sixth threshold, seventh threshold, eighth threshold, ninth threshold, tenth threshold, and eleventh threshold increase sequentially; the first constant ≥ the second constant > the third constant > the fourth constant > the fifth constant ≥ the sixth constant; the environmental parameter g is specified to have a range of 0-10.

[0035] In this embodiment, dividing the outdoor ambient temperature into different temperature ranges and assigning different environmental parameters to each range improves the accuracy of oil temperature determination. Specifically, as the outdoor ambient temperature increases, its impact on the discharge performance of the compressor 11 weakens; therefore, the value of the environmental parameter g is reduced. Furthermore, by rationally setting the range of the specified environmental parameter, the accuracy of oil temperature determination can be improved, facilitating timely responses to oil shortages, enhancing the safety and stability of compressor 11 operation, and extending its service life. The relationship between the environmental parameter g and the outdoor ambient temperature in this embodiment is shown in the table below:

[0036] In a preferred embodiment of the present invention, when the first difference < h and lasts for a second duration t2; and when the second difference < d, the oil temperature Tk is determined to be unqualified and the compressor 11 is short of oil; when i ≤ the first difference < j and lasts for a third duration t3; and when the second difference ≥ d, the current oil temperature Tk determination result is maintained; when the first difference ≥ k and lasts for a fourth duration t4; and when the second difference ≥ d, the oil temperature Tk is determined to be qualified; wherein d, h, i, j, and k are constants, and h, i, j, and k increase sequentially.

[0037] Specifically, when the first difference is less than h and lasts for a second duration t2, it indicates that the difference between the exhaust temperature and the refrigerant high-pressure saturation temperature and the specified environmental parameters is small, the exhaust of compressor 11 has not reached the effective superheat range, and compressor 11 may be short of oil.

[0038] When i ≤ the first difference < j and this condition persists for a third duration t3, it indicates that the difference between the exhaust temperature and the refrigerant high-pressure saturation temperature and the specified environmental parameters has not been identified as oil shortage within the third duration. The compressor 11's operating state is relatively stable, maintaining the current oil temperature Tk determination result, i.e., maintaining the previous oil temperature determination result. If the previous determination result indicated that the compressor 11 was oil-deficient, an oil return procedure is executed to increase the oil temperature of the compressor 11; if the previous determination result indicated that the compressor 11 was not oil-deficient, the oil return procedure is not executed, and the current operating state is maintained.

[0039] When the first difference is ≥ k and persists for a duration of t4, it indicates that the difference between the exhaust temperature and the refrigerant high-pressure saturation temperature and the specified environmental parameters is relatively high. The compressor 11 is within the normal operating range of exhaust superheat, and the compressor 11 is not short of oil. By dividing the first difference into three different ranges, the accuracy of oil temperature judgment is improved. When the first difference is within the range i~j, the current oil temperature judgment result is maintained, and the operation of the air conditioning system is controlled based on the current oil temperature judgment result, thus improving the stability of the air conditioning system operation. Specifically, the values ​​of h, i, j, and k range from 0 to 15, that is, the value range of the first preset value is 0~15. Specifically, h=0, i=2, j=4, k=5. In this embodiment, by reasonably setting the value ranges of the first and second preset values, the accuracy of oil temperature judgment can be improved, which is beneficial for timely corresponding measures when oil shortage occurs, improving the safety and stability of compressor 11 operation, and extending the service life of compressor 11.

[0040] Furthermore, when the second difference is ≥ d, it indicates that the return gas temperature is relatively high, that is, the oil temperature in compressor 11 is within the normal range. Conversely, when the second difference is < d, it indicates that the return gas temperature is relatively low, and compressor 11 may be short of oil. In this embodiment, the value of d is 0-10, preferably d=3.

[0041] This implementation improves the accuracy of oil temperature determination by simultaneously judging the first difference, the second difference, and the duration, avoiding unnecessary execution of the oil return procedure and ensuring the stable and reliable operation of the air conditioning system. Furthermore, by combining the operating time of the air conditioning system under the corresponding judgment conditions to determine whether the oil temperature is qualified, oil temperature determination is performed during stable air conditioning operation, further ensuring the accuracy of the judgment result.

[0042] In a preferred embodiment of the present invention, the oil temperature determination step further includes: Frequency acquisition steps: Acquire the operating parameters of compressor 11, including the operating frequency F and operating time t of compressor 11; Judgment steps: Determine whether the operating parameters meet the oil temperature judgment conditions; the oil temperature judgment conditions are: the operating frequency is not less than the specified frequency threshold, and the operating time is not less than the first duration t1; Control steps: If the operating parameters meet the oil temperature judgment conditions, the control will execute the oil temperature judgment step.

[0043] By employing the above method, when the operating parameters of compressor 11 meet the oil temperature judgment conditions, the oil temperature judgment step is executed, avoiding frequent initiation of the oil temperature judgment step. This helps ensure the operating efficiency and reliable operation of the air conditioning system. Furthermore, when the operating frequency of compressor 11 is not less than a specified frequency threshold and the operating time is not less than a first duration, compressor 11 operates stably in this state. Performing oil temperature judgment under these conditions improves the accuracy of the judgment results. In this embodiment, the first duration ranges from 5 to 30 minutes; here, 16 minutes is used.

[0044] In this embodiment, the frequency range is 30-60, and preferably, the frequency value c=45.

[0045] In a preferred embodiment of the present invention, the control device is configured to perform an oil temperature fault detection step before the frequency acquisition step; the oil temperature fault detection step includes: Determine if the oil temperature Tk is within the fault temperature range (Tk b). If the oil temperature Tk is within the fault temperature range, output that the oil temperature sensor 5 is faulty.

[0046] In this embodiment, the oil temperature sensor 5 is directly obtained to determine whether the temperature detection result falls within the fault temperature range, and thus whether the oil temperature sensor 5 is faulty. This method is simple, convenient, and easy to implement.

[0047] In some implementations, the oil temperature sensor 5 transmits oil temperature information by emitting an analog electrical signal AD. By judging the range of the analog electrical signal, it is determined whether the oil temperature sensor 5 is faulty. For example, a and b are both constants, and the values ​​of a and b are 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.

[0048] In a preferred embodiment of the present invention, if the oil temperature Tk is not within the fault temperature range, the control device is configured to execute: Frequency comparison steps: Compare the operating frequency with the specified frequency threshold; Second difference comparison step: Compare the second difference with the second preset value; Data processing steps: Calculate the difference between exhaust temperature Tp and oil temperature Tk, denoted as the third difference Tp-Tk; and compare the third difference with the difference threshold. Fault diagnosis steps: Based on the comparison results of the frequency comparison step, the second difference comparison step, and the data processing step, determine whether the oil temperature sensor 5 is faulty.

[0049] In this embodiment, by combining the operating frequency of the compressor 11, the suction superheat, and the range of the third difference, it is beneficial to improve the accuracy of the fault judgment of the oil temperature sensor 5.

[0050] In this embodiment, Tp-Tk≥e, where e is the difference threshold, and the value of e ranges from 10 to 20, and is 16 here.

[0051] In a preferred embodiment of the present invention, the fault judgment step further includes: when the operating frequency is greater than a specified frequency threshold, when the second difference is not less than a second preset value, and when the third difference is greater than a difference threshold, an output fault is generated for the oil temperature sensor 5. When the operating frequency is high and the intake superheat is within a reasonable range, judging whether the oil temperature sensor 5 is faulty based on the comparison result of the third difference and the difference threshold helps to improve the accuracy of oil temperature judgment.

[0052] It should be noted that the values ​​exemplified in this embodiment are preferred values. Technicians can adjust them according to the actual operating conditions of the air conditioning system and the equipment parameters of the air conditioning system, and are not limited to these values.

[0053] <Second Implementation Method> like Figure 3 As shown, the present invention provides an air conditioning system, including 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 is mixed 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 discharge port, a first suction port, and a first oil return port; the second compressor 112 has a first discharge port, a first suction port, and a first oil return port. Further, the air conditioning system also includes: The first temperature sensor 21 is used to detect the exhaust temperature Tpa of the first compressor 111; The second temperature sensor 22 is used to detect the exhaust temperature Tpb of the second compressor 112; The first oil temperature sensor 51 is used to detect the return oil temperature Tka of the first compressor 111; The second oil temperature sensor 52 is used to detect the return oil temperature Tkb of the second compressor 112; High-pressure sensor 31 is used to detect the high-pressure Hp of the air conditioning system; Low-pressure sensor 32 is used to detect the low-pressure Lp of the air conditioning system; 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. The second oil return line 62 is connected to the second oil return port and the second compressor 112. The second oil temperature sensor 52 is located in the second oil return line 62. The inlet of the first oil separator 161 is connected to the outlet of the first compressor 111, and the outlet is connected to the first oil return port through the first oil return pipeline 61. 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 oil return port through the second oil return pipeline 62.

[0054] 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. 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.

[0055] In this embodiment, the control device is configured to execute the oil temperature judgment program corresponding to the first compressor 111 and the oil temperature judgment program corresponding to the second compressor 112. The oil temperature judgment program corresponding to the first compressor 111 and the oil temperature judgment program corresponding to the second compressor 112 are the oil temperature judgment methods disclosed in the first embodiment. Figure 4 The diagram illustrates the oil temperature determination procedures for the first compressor 111 and the second compressor 112. These procedures are combined, but the oil temperature determination procedures for the two compressors are independent. The "and" sign in the diagram indicates that both conditions on either side of the "and" sign are evaluated. For the specific determination process, please refer to [reference needed]. Figure 4 The process will not be elaborated here. It should be noted that in this embodiment, Tp represents Tpa or Tpb, and Tk represents Tka or Tkb. For example, when determining whether the oil temperature of the first compressor 111 is qualified, the first difference is Tpa-Tc-g; when determining whether the oil temperature of the second compressor 112 is qualified, the first difference is Tpb-Tc-g; a Tpa fault indicates a fault in the temperature sensor corresponding to the first compressor 111, and a Tpb fault indicates a fault in the temperature sensor corresponding to the second compressor 112.

[0056] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An 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, characterized in that, Also includes: An exhaust temperature sensor is used to detect the exhaust temperature Tp 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; A return air temperature sensor is used to detect the return air temperature Ts of the air conditioning system; An ambient temperature sensor is used to detect the outdoor ambient temperature. The control device is configured to perform an oil temperature determination step; the oil temperature determination step includes: Parameter acquisition steps: Acquire the high-pressure saturation temperature Tc, low-pressure saturation temperature Te, high-pressure pressure Hp, low-pressure pressure Lp, and return gas temperature Ts of the air conditioning system; Environmental parameter determination steps: Obtain the outdoor ambient temperature, and determine the corresponding specified environmental parameters based on the outdoor ambient temperature; Calculation steps: Calculate the first difference and the second difference. The first difference is the difference between the exhaust temperature Tp, the high-pressure saturation temperature Tc, and the specified environmental parameter g, which is Tp-Tc-g. The second difference is the difference between the return gas temperature Ts and the low-pressure saturation temperature Te. Comparison steps: Compare the first difference with the corresponding first preset value, and compare the second difference with the corresponding second preset value; Judgment Step: Based on the comparison results of the comparison step, determine whether the oil temperature of the compressor is qualified. Specifically, when the first difference is less than h and lasts for the second duration, and when the second difference is less than d, the oil temperature Tk is determined to be unqualified and the compressor is short of oil. When i ≤ the first difference < j, and this continues for the third duration; and when the second difference ≥ d, the current oil temperature Tk determination result is maintained. When the first difference is ≥ k and lasts for four hours; and when the second difference is ≥ d, the oil temperature Tk is deemed to be qualified; where d, h, i, j, and k are constants, and h, i, j, and k increase sequentially.

2. The air conditioning system according to claim 1, characterized in that, If the outdoor ambient temperature is less than or equal to a first threshold, then the specified environmental parameter is a first constant. If the second threshold ≤ the outdoor ambient temperature ≤ the third threshold, then the specified environmental parameter g is the second constant; If the fourth threshold ≤ the outdoor ambient temperature ≤ the fifth threshold, then the specified environmental parameter g is the third constant; If the sixth threshold ≤ the outdoor ambient temperature ≤ the seventh threshold, then the specified environmental parameter g is the fourth constant; If the eighth threshold ≤ the outdoor ambient temperature ≤ the ninth threshold, then the specified environmental parameter g is the fifth constant; If the tenth threshold ≤ the outdoor ambient temperature ≤ the eleventh threshold, then the specified environmental parameter g is the sixth constant; where, The first threshold, second threshold, third threshold, fourth threshold, fifth threshold, sixth threshold, seventh threshold, eighth threshold, ninth threshold, tenth threshold, and eleventh threshold increase sequentially; the first constant ≥ the second constant > the third constant > the fourth constant > the fifth constant ≥ the sixth constant.

3. The air conditioning system according to claim 1, characterized in that, The specified environmental parameters have a value range of 0-10.

4. The air conditioning system according to claim 1, characterized in that, The first preset value ranges from 0 to 15; the second preset value ranges from 0 to 15.

5. The air conditioning system according to claim 1, characterized in that, The oil temperature determination step also includes: Frequency acquisition step: Acquire the operating parameters of the compressor, including the operating frequency and operating duration of the compressor; Judgment steps: Determine whether the operating parameters meet the oil temperature judgment conditions; the oil temperature judgment conditions are: the operating frequency is not less than a specified frequency threshold, and the operating duration is not less than a first duration; Control steps: If the operating parameters meet the oil temperature judgment conditions, control the execution of the oil temperature judgment step.

6. The air conditioning system according to claim 5, characterized in that, Also includes: An oil temperature sensor is used to detect the oil temperature Tk of the compressor; The control device is configured to perform an oil temperature fault detection step before the frequency acquisition step; The oil temperature fault detection steps include: Determine whether the oil temperature Tk is within the fault temperature range. If the oil temperature Tk is within the fault temperature range, output that the oil temperature sensor is faulty.

7. The air conditioning system according to claim 6, characterized in that, If the oil temperature Tk is not within the fault temperature range, the control device is configured to execute: Frequency comparison step: Compare the operating frequency with the specified frequency threshold; Second difference comparison step: Compare the second difference with the second preset value; Data processing steps: Calculate the difference between the exhaust temperature Tp and the oil temperature Tk, and record it as the third difference; And compare the third difference with the difference threshold; Fault diagnosis steps: Based on the comparison results of the frequency comparison step, the comparison results of the second difference comparison step, and the comparison results of the data processing step, determine whether the oil temperature sensor is faulty.

8. The air conditioning system according to claim 7, characterized in that, In the fault diagnosis step, when the operating frequency is greater than the specified frequency threshold, the second difference is not less than the second preset value and the third difference is greater than the difference threshold, the oil temperature sensor fault is output.

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