High-reliability air compressor temperature and pressure detection method

Abstract

According to the high-reliability air compressor temperature and pressure detection method, the first-stage exhaust temperature is calculated through the air inlet pressure, the final exhaust pressure, the total compression ratio and the air inlet temperature, an air side temperature calculation model and a cooling liquid side temperature calculation model are established, and the dynamic characteristics of the model are described through a first-order inertia link; describing a first law of open system thermodynamics, and training according to experimental data to obtain an accurate model; when the failure of the temperature sensor or the pressure sensor is detected, the system can be automatically adjusted, the exhaust temperature and the exhaust pressure of each stage of the air compressor are calculated in real time according to the established model, and the efficient operation of the air compressor system is ensured.

Description

Technical Field

[0001] The invention relates to the field of air compressor frequency converters, and in particular to a high-reliability air compressor temperature and pressure detection method. Background Art

[0002] Air compressor is a commonly used equipment. To ensure the normal operation of the air compressor, its operating data must be monitored, including pressure, temperature, flow, voltage, etc. These parameters have a direct impact on the operating status and performance of the air compressor. The air compressor pressure refers to the pressure in the compressed air. Reasonable pressure can ensure the normal operation of the air compressor system and save energy. The exhaust temperature of the air compressor is one of the important indicators for evaluating its operating status. Exhaust temperature within the range not only helps to maintain the performance of the air compressor, but also prevents potential equipment failures. Excessive exhaust temperature may cause lubricating oil deterioration, increased equipment wear, and even cause safety accidents such as fire. Therefore, timely and accurate detection of exhaust pressure and exhaust temperature is of great significance to ensure the safe operation of the air compressor.

[0003] At present, the detection of exhaust pressure and exhaust temperature of air compressors is usually achieved through pressure sensors and temperature sensors. In the actual working environment of air compressors, due to various complex situations such as long-term operation of air compressors and high-temperature working environment, it is very likely that its temperature sensor or pressure sensor will be damaged, and temperature and pressure affect each other. When one of them fails, it is very likely to cause the air compressor system to fail and cannot operate normally, resulting in huge economic and energy losses. Summary of the invention

[0004] To solve the above problems, the present invention proposes a high-reliability air compressor temperature and pressure detection method. When it is detected that the temperature sensor or pressure sensor fails, the air compressor exhaust temperature is calculated by establishing a dynamic model of the air side and the coolant side, and then the exhaust pressure is reversed according to the exhaust temperature, thereby realizing automatic adjustment of the system and ensuring the efficient operation of the air compressor system.

[0005] The present invention provides a high-reliability air compressor temperature and pressure detection method, comprising the following steps:

[0006] Step S1, determining the first-stage air intake pressure of the air compressor , Final exhaust pressure , total compression ratio , first stage inlet temperature ; The total compression ratio The calculation formula is: , in, is the overall compression ratio, is the final exhaust pressure, is the first stage intake pressure.

[0007] Step S2, calculating the theoretical compression ratio of each stage of the multi-stage air compressor based on the minimum compression power consumption theory , n=1,2,3,4,…, n is a natural number starting from 1, where the theoretical compression ratio of each level is The calculation formula is: , in, is the theoretical compression ratio at each level, and n is a natural number starting from 1.

[0008] In the actual design process, in order to improve the volumetric efficiency of the air compressor, the actual compression ratio of the first stage is Compared with the first-stage theoretical compression ratio Small, so the first-stage theoretical compression ratio Correction is performed to obtain the actual compression ratio of the first stage Similarly, the actual compression ratio of each level can be obtained .

[0009] Step S3, based on the actual compression ratio of the first level , Multi-stage air compressor first stage inlet pressure Calculate the first stage exhaust pressure , according to the first-stage intake air temperature Calculate the primary exhaust temperature .

[0010] Among them, the first-stage exhaust pressure The calculation formula is: , in, is the first-stage exhaust pressure, is the actual compression ratio of the first stage; First stage exhaust temperature The calculation formula is: , in, is the first-stage exhaust temperature, is the first stage inlet temperature, and q is the temperature adiabatic index.

[0011] Step S4, at time k, establish temperature detection dynamic models for the air side and the coolant side, respectively. For the air side: , in, is the constant pressure specific heat of the gas, is the mass of gas flowing into the cooler at time k, is the gas temperature when it flows into the cooler at time k, is the gas temperature when it flows out of the cooler at time k, is the heat transfer on both sides of the cooler at time k, is the specific heat at constant volume of the gas, is the mass of gas in the cooler at time k, is the gas temperature in the cooler at time k, d is the differential operator, and t is the time.

[0012] Coolant side: , , , in, is the specific heat capacity of the coolant, is the mass of coolant flowing into the cooler at time k, is the coolant temperature when it flows into the cooler at time k, is the coolant temperature when it flows out of the cooler at time k, is the mass of coolant in the cooler at time k, is the temperature of the coolant in the cooler at time k, is the heat transfer coefficient, is the heat exchange area, It is the difference between the gas temperature when it flows out of the cooler at time k and the coolant temperature when it flows out of the cooler at time k.

[0013] After the dynamic models of the air side and the coolant side are established, n sets of real-time data including mass and gas temperature when entering and leaving the cooler are collected, where n is a natural number starting from 1. , and , Finally, by solving the differential equations, accurate models of the gas side and the coolant side can be trained to calculate the temperature of the gas and coolant at any time.

[0014] Step S5, judging the fault status of the temperature sensor and the pressure sensor. If the temperature sensor fails, proceed to step S6; if the pressure sensor fails, proceed to step S7.

[0015] Step S6, when the temperature sensor fails, the trained air-side dynamic model and coolant-side dynamic model are used to estimate the exhaust temperature after each stage of compression and the temperature of the gas and coolant at any time during the cooling process starting from time k+2. The specific process is as follows: The first stage exhaust temperature can be calculated from the first stage inlet temperature and gas type : , In the cooling stage, the gas temperature and the coolant temperature in the cooler at any time and at any level can be calculated according to the air side dynamic model and the coolant side dynamic model in step S4.

[0016] Step S7, when the pressure sensor fails, the pressure of the compressed gas is inferred from the temperature of each level of exhaust gas after compression detected by the temperature detector starting from time k+2.

[0017] The specific process is as follows: According to the exhaust temperature calculation formula of each stage of compression part: , The calculation formula for exhaust pressure at each stage of compression is: , in, is the n-stage exhaust temperature, is the n-stage intake temperature, is the actual compression ratio of level n, q is the temperature adiabatic index, is the n-stage exhaust pressure, is the n-th stage intake pressure, where n is a natural number starting from 1.

[0018] According to the first-stage intake air temperature The temperature detector detects the primary exhaust temperature , reverse the actual compression ratio of the first stage , by the first exhaust pressure in S3 The calculation formula is used to obtain the first-stage exhaust pressure. The second-stage compression and subsequent compression levels are analogous. According to the detected exhaust temperature of each level, the actual compression ratio of each level is inferred. The intake pressure of each stage is equal to the exhaust pressure of the previous stage. The exhaust pressure of each stage can be calculated based on the exhaust pressure calculation formula of the compression part.

[0019] Furthermore, the actual compression ratio of the first stage The calculation formula is: , in, is the actual compression ratio of the first stage, It is the first-level theoretical compression ratio.

[0020] According to the total compression ratio of the multi-stage air compressor According to the isobaric ratio theory, the actual compression ratios of other levels are also corrected accordingly. The calculation formula is: , in, is the actual compression ratio of level n, is the total compression ratio, and n is a natural number starting from 1.

[0021] Furthermore, the temperature sensor fault state judgment conditions are as follows: Set temperature threshold a Set the dead zone interval based on temperature threshold a Where φ is the temperature threshold tolerance range; record the air temperature detected by the temperature sensor at time k And the air temperature detected at time k+1 Calculate the gas temperature at time k and time k+1 according to the air side dynamic model established in step S4 , .

[0022] When the temperature sensor records the gas temperature at time k and the gas temperature at time k+1 Calculate the temperature at time k and time k+1 with the air side dynamic model , When the following conditions are met, the temperature sensor is diagnosed as faulty; , and , And from time k At time k+1 Mutation occurs; in, is the temperature calculated by the air side dynamic model and the coolant side dynamic model at time k, is the air temperature recorded by the temperature sensor at time k, a is the temperature threshold, φ is the temperature threshold tolerance range, is the temperature calculated by the air side dynamic model and the coolant side dynamic model at time k+1, is the air temperature recorded by the temperature sensor at time k+1, is the empty set symbol, is the intersection symbol, For square brackets.

[0023] Furthermore, the pressure sensor fault state judgment conditions are as follows: Set the pressure threshold b, and set the dead zone interval based on the pressure threshold b ,in is the pressure threshold tolerance range; records the exhaust pressures of each level detected by the pressure sensor at time k And the exhaust pressure of each level detected at time k+1 .

[0024] When the pressure sensor records the pressure at time k And the pressure at k+1 and pressure threshold b, pressure threshold tolerance range The pressure sensor is diagnosed as faulty when the following conditions are met: , and , And from time k At time k+1 Mutation occurs; in, is the pressure recorded by the pressure sensor at time k, is the pressure recorded by the pressure sensor at time k+1, b is the pressure threshold, is the pressure threshold tolerance range.

[0025] The technical effects of the present invention are: 1. The established dynamic model for temperature calculation on the air side and coolant side is accurate, realizing redundant fault-tolerant control of temperature and pressure; 2. The system can automatically adjust to ensure efficient operation of the air compressor system. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 A flowchart of the algorithm steps provided by the present invention; Figure 2 A temperature detection and judgment flow chart provided by the present invention; Figure 3 This is a pressure detection and judgment flow chart provided by the present invention. DETAILED DESCRIPTION

[0027] The following is only a preferred embodiment of the present invention. The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments, so that those skilled in the art can understand the present invention. It should be pointed out that for those of ordinary skill in the art, as long as various changes are within the spirit and scope of the present invention defined and determined by the attached claims without departing from the principle of the present invention, all inventions and creations using the concept of the present invention are protected.

[0028] Figure 1 The method step flow chart provided by the present invention is as follows: Figure 1 As shown, a high-reliability air compressor temperature and pressure detection method includes the following steps: Step S1, determining the first-stage air intake pressure of the air compressor , Final exhaust pressure , total compression ratio , first stage inlet temperature ; The total compression ratio The calculation formula is: , in, is the overall compression ratio, is the final exhaust pressure, is the first stage intake pressure.

[0029] Step S2, calculating the theoretical compression ratio of each stage of the multi-stage air compressor based on the minimum compression power consumption theory , n=1,2,3,4,…, n is a natural number starting from 1, where the theoretical compression ratio of each level is The calculation formula is: , in, is the theoretical compression ratio at each level, and n is a natural number starting from 1.

[0030] In the actual design process, in order to improve the volumetric efficiency of the air compressor, the actual compression ratio of the first stage is Compared with the first-stage theoretical compression ratio Small, so the first-stage theoretical compression ratio Correction is performed to obtain the actual compression ratio of the first stage Similarly, the actual compression ratio of each level can be obtained .

[0031] Among them, the actual compression ratio of the first stage The calculation formula is: , in, is the actual compression ratio of the first stage, It is the first-level theoretical compression ratio.

[0032] According to the total compression ratio of the multi-stage air compressor According to the isobaric ratio theory, the actual compression ratios of other levels are also corrected accordingly. The calculation formula is: , in, is the actual compression ratio of level n, is the total compression ratio, and n is a natural number starting from 1.

[0033] Step S3, based on the actual compression ratio of the first level , Multi-stage air compressor first stage inlet pressure Calculate the first stage exhaust pressure , according to the first-stage intake air temperature Calculate the primary exhaust temperature .

[0034] Among them, the first-stage exhaust pressure The calculation formula is: , in, is the first-stage exhaust pressure, is the actual compression ratio of the first stage; First stage exhaust temperature The calculation formula is: , in, is the first-stage exhaust temperature, is the first stage inlet temperature, and q is the temperature adiabatic index.

[0035] Step S4, at time k, establish temperature detection dynamic models for the air side and the coolant side, respectively. For the air side: , in, is the constant pressure specific heat of the gas, is the mass of gas flowing into the cooler at time k, is the gas temperature when it flows into the cooler at time k, is the gas temperature when it flows out of the cooler at time k, is the heat transfer on both sides of the cooler at time k, is the specific heat at constant volume of the gas, is the mass of gas in the cooler at time k, is the gas temperature in the cooler at time k, d is the differential operator, and t is the time.

[0036] Coolant side: , , , in, is the specific heat capacity of the coolant, is the mass of coolant flowing into the cooler at time k, is the coolant temperature when it flows into the cooler at time k, is the coolant temperature when it flows out of the cooler at time k, is the mass of coolant in the cooler at time k, is the temperature of the coolant in the cooler at time k, is the heat transfer coefficient, is the heat exchange area, It is the difference between the gas temperature when it flows out of the cooler at time k and the coolant temperature when it flows out of the cooler at time k.

[0037] After the dynamic models of the air side and the coolant side are established, n sets of real-time data including mass and gas temperature when entering and leaving the cooler are collected, where n is a natural number starting from 1. , and , Finally, by solving the differential equations, accurate models of the gas side and the coolant side can be trained to calculate the temperature of the gas and coolant at any time.

[0038] Step S5, judging the fault status of the temperature sensor and the pressure sensor. If the temperature sensor fails, proceed to step S6; if the pressure sensor fails, proceed to step S7. Figure 2 The temperature detection and judgment flow chart provided by the present invention is as follows: Figure 2 As shown in the figure, the temperature sensor fault status judgment conditions are as follows: Set temperature threshold a Set the dead zone interval based on temperature threshold a , where φ is the temperature threshold tolerance range; record the air temperature detected by the temperature sensor at time k And the air temperature detected at time k+1 Calculate the gas temperature at time k and time k+1 according to the air side dynamic model established in step S4 , ; When the temperature sensor records the gas temperature at time k and the gas temperature at time k+1 Calculate the temperature at time k and time k+1 with the air side dynamic model , When the following conditions are met, the temperature sensor is diagnosed as faulty; , and , And from time k At time k+1 Mutation occurs; in, is the temperature calculated by the air side dynamic model and the coolant side dynamic model at time k, is the air temperature recorded by the temperature sensor at time k, a is the temperature threshold, φ is the temperature threshold tolerance range, is the temperature calculated by the air side dynamic model and the coolant side dynamic model at time k+1, is the air temperature recorded by the temperature sensor at time k+1, is the empty set symbol, is the intersection symbol, For square brackets.

[0039] Figure 3 The pressure detection and judgment flow chart provided by the present invention is as follows: Figure 3 As shown in the figure, the pressure sensor fault status judgment conditions are as follows: Set the pressure threshold b, and set the dead zone interval based on the pressure threshold b ,in is the pressure threshold tolerance range; records the exhaust pressures of each level detected by the pressure sensor at time k And the exhaust pressure of each level detected at time k+1 ; When the pressure sensor records the pressure at time k And the pressure at k+1 and pressure threshold b, pressure threshold tolerance range The pressure sensor is diagnosed as faulty when the following conditions are met: , and , And from time k At time k+1 Mutation occurs; in, is the pressure recorded by the pressure sensor at time k, is the pressure recorded by the pressure sensor at time k+1, b is the pressure threshold, is the pressure threshold tolerance range.

[0040] Step S6, when the temperature sensor fails, the trained air-side dynamic model and coolant-side dynamic model are used to estimate the exhaust temperature after each stage of compression and the temperature of the gas and coolant at any time during the cooling process starting from time k+2. The specific process is as follows: The first stage exhaust temperature can be calculated from the first stage inlet temperature and gas type : , In the cooling stage, the gas temperature and the coolant temperature in the cooler at any time and at any level can be calculated according to the air side dynamic model and the coolant side dynamic model in step S4.

[0041] Step S7, when the pressure sensor fails, the pressure of the compressed gas is inferred from the temperature of each level of exhaust gas after compression detected by the temperature detector starting from time k+2.

[0042] The specific process is as follows: According to the exhaust temperature calculation formula of each stage of compression part: , The calculation formula of exhaust pressure at each stage of compression part is: , in, is the n-stage exhaust temperature, is the n-stage intake temperature, is the actual compression ratio of level n, q is the temperature adiabatic index, is the n-stage exhaust pressure, is the n-th stage intake pressure, where n is a natural number starting from 1.

[0043] According to the first-stage intake air temperature The temperature detector detects the primary exhaust temperature , reverse the actual compression ratio of the first stage , by the first exhaust pressure in S3 The calculation formula is used to obtain the first-stage exhaust pressure. The second-stage compression and subsequent compression levels are analogous. According to the detected exhaust temperature of each level, the actual compression ratio of each level is inferred. The intake pressure of each stage is equal to the exhaust pressure of the previous stage. The exhaust pressure of each stage can be calculated based on the exhaust pressure calculation formula of the compression part.

[0044] According to the design requirements of engineering practice, the performance indicators of the two-stage air compressor are formulated, and the above method is practiced with simulated data. The specific contents are as follows: The intake pressure is 0.1MPa and the exhaust pressure is 2MPa.

[0045] According to step S1 to step S3, it can be known that , , , , .

[0046] The intake air temperature is the actual atmospheric temperature during the test. .

[0047] The air side parameters and coolant side parameters at time k are shown in Table 1 and Table 2: Table 1 Air side parameters at time k

[0048] Table 2 Coolant side parameters at time k

[0049] Fitting the heat transfer coefficient .

[0050] The temperature calculation formula of gas and coolant at any time is obtained by calculating the differential equation: , Air side dynamic equation: , Coolant side dynamic equation: , Will Substituting the air side dynamic equation and the coolant side dynamic equation into the two equations in parallel, we can get two differential equations: , , Finally, the Runge-Kutta method is used to program a numerical solution to determine the temperature of the gas and coolant at any time.

[0051] By detecting the temperature of the temperature sensor and the pressure sensor, it is determined whether the sensor is faulty at a certain moment. If the temperature sensor fails, the temperature at any moment can be solved by adding the model. If the pressure sensor fails, the gas pressure after compression can be inferred based on the exhaust temperature after each stage of compression detected by the temperature detector.

[0052] Although the specific implementation of the invention is described in detail in conjunction with the drawings, it should not be understood as limiting the scope of protection of this patent. Within the scope described in the claims, various modifications and variations that can be made by those skilled in the art without creative work still fall within the scope of protection of this patent.

Claims

1. A highly reliable air compressor temperature and pressure detection method, characterized in that: The following steps are involved: Step S1, determining the first-stage air intake pressure of the air compressor , Final exhaust pressure , total compression ratio , first stage inlet temperature ; Among them, the total compression ratio The calculation formula is: ， in, is the overall compression ratio, is the final exhaust pressure, is the first stage intake pressure; Step S2, calculating the theoretical compression ratio of each stage of the multi-stage air compressor based on the minimum compression power consumption theory , n=1,2,3,4,…, n is a natural number starting from 1, where the theoretical compression ratio of each level is The calculation formula is: ， in, is the theoretical compression ratio at each level, and n is a natural number starting from 1; In the actual design process, in order to improve the volumetric efficiency of the air compressor, the actual compression ratio of the first stage is Compared with the first-stage theoretical compression ratio Small, so the first-stage theoretical compression ratio Correction is performed to obtain the actual compression ratio of the first stage Similarly, the actual compression ratio of each level can be obtained ; Step S3, based on the actual compression ratio of the first level , Multi-stage air compressor first stage inlet pressure Calculate the first stage exhaust pressure , according to the first-stage intake air temperature Calculate the primary exhaust temperature ; Among them, the first-stage exhaust pressure The calculation formula is: ， in, is the first-stage exhaust pressure, is the actual compression ratio of the first stage; First stage exhaust temperature The calculation formula is: ， in, is the first-stage exhaust temperature, is the first-stage inlet temperature, q is the temperature adiabatic index; Step S4, at time k, establish temperature detection dynamic models for the air side and the coolant side, respectively. For the air side: ， in, is the constant pressure specific heat of the gas, is the mass of gas flowing into the cooler at time k, is the gas temperature when it flows into the cooler at time k, is the gas temperature when it flows out of the cooler at time k, is the heat transfer on both sides of the cooler at time k, is the specific heat at constant volume of the gas, is the mass of gas in the cooler at time k, is the gas temperature in the cooler at time k, d is the differential operator, and t is the time; Coolant side: ， ， ， in, is the specific heat capacity of the coolant, is the mass of coolant flowing into the cooler at time k, is the coolant temperature when it flows into the cooler at time k, is the coolant temperature when it flows out of the cooler at time k, is the mass of coolant in the cooler at time k, is the temperature of the coolant in the cooler at time k, is the heat transfer coefficient, is the heat exchange area, is the difference between the gas temperature when it flows out of the cooler at time k and the coolant temperature when it flows out of the cooler at time k; After the dynamic models of the air side and the coolant side are established, n sets of real-time data including mass and gas temperature when entering and leaving the cooler are collected, where n is a natural number starting from 1. , and , After that, by solving the differential equations, the accurate models of the gas side and the coolant side can be trained to calculate the temperature of the gas and coolant at any time; Step S5, judging the fault status of the temperature sensor and the pressure sensor. If the temperature sensor fails, the process goes to step S6; if the pressure sensor fails, the process goes to step S7; Step S6, when the temperature sensor fails, the trained air-side dynamic model and coolant-side dynamic model are used to estimate the exhaust temperature after each stage of compression and the temperature of the gas and coolant at any time during the cooling process starting from time k+2. The specific process is as follows: The first stage exhaust temperature can be calculated from the first stage inlet temperature and gas type : ， In the cooling stage, the air side dynamic model and the coolant side dynamic model described in step S4 can calculate the gas temperature and the coolant temperature in the cooler at any time and any level; Step S7, when the pressure sensor fails, the pressure of the compressed gas is inferred from the exhaust temperatures of each level after compression detected by the temperature detector starting from time k+2. The specific process is as follows: According to the exhaust temperature calculation formula of each stage of compression part: ， The calculation formula for exhaust pressure at each stage of compression is: ， in, is the n-stage exhaust temperature, is the n-stage intake temperature, is the actual compression ratio of level n, q is the temperature adiabatic index, is the n-stage exhaust pressure, is the n-stage intake pressure, where n is a natural number starting from 1; According to the first-stage intake air temperature The temperature detector detects the primary exhaust temperature , reverse the actual compression ratio of the first stage , the first-stage exhaust pressure in S3 The calculation formula is used to obtain the first-stage exhaust pressure. The second-stage compression and subsequent compression levels are analogous. According to the detected exhaust temperature of each level, the actual compression ratio of each level is inferred. The intake pressure of each stage is equal to the exhaust pressure of the previous stage. The exhaust pressure of each stage can be calculated based on the exhaust pressure calculation formula of the compression part.

2. A high-reliability air compressor temperature and pressure detection method according to claim 1, characterized in that: In step S2, the first-level actual compression ratio The calculation formula is: ， in, is the actual compression ratio of the first stage, is the first-level theoretical compression ratio; According to the total compression ratio of the multi-stage air compressor According to the isobaric ratio theory, the actual compression ratios of other levels are also corrected accordingly. The calculation formula is: ， in, is the actual compression ratio of level n, is the total compression ratio, and n is a natural number starting from 1.

3. A high-reliability air compressor temperature and pressure detection method according to claim 1, characterized in that: In step S5, the temperature sensor fault state judgment condition is as follows: Set temperature threshold a Set the dead zone interval based on temperature threshold a Where φ is the temperature threshold tolerance range; record the air temperature detected by the temperature sensor at time k And the air temperature detected at time k+1 Calculate the gas temperature at time k and time k+1 according to the air side dynamic model established in step S4 , ; When the temperature sensor records the gas temperature at time k and the gas temperature at time k+1 Calculate the temperature at time k and time k+1 with the air side dynamic model , When the following conditions are met, the temperature sensor is diagnosed as faulty; ， and , And from time k At time k+1 Mutation occurs; in, is the temperature calculated by the air side dynamic model and the coolant side dynamic model at time k, is the air temperature recorded by the temperature sensor at time k, a is the temperature threshold, φ is the temperature threshold tolerance range, is the temperature calculated by the air side dynamic model and the coolant side dynamic model at time k+1, is the air temperature recorded by the temperature sensor at time k+1, is the empty set symbol, is the intersection symbol, For square brackets.

4. A high-reliability air compressor temperature and pressure detection method according to claim 1, characterized in that: In step S5, the pressure sensor fault state judgment condition is as follows: Set the pressure threshold b, and set the dead zone interval based on the pressure threshold b ,in is the pressure threshold tolerance range; records the exhaust pressures of each level detected by the pressure sensor at time k And the exhaust pressure of each level detected at time k+1 ; When the pressure sensor records the pressure at time k And the pressure at k+1 and pressure threshold b, pressure threshold tolerance range The pressure sensor is diagnosed as faulty when the following conditions are met: ， and , And from time k At time k+1 Mutation occurs; in, is the pressure recorded by the pressure sensor at time k, is the pressure recorded by the pressure sensor at time k+1, b is the pressure threshold, is the pressure threshold tolerance range.

Images