An aircraft air conditioning system servicing and testing device

Abstract

This invention relates to a maintenance and testing device for an aircraft air conditioning system. An engine testing module emits sound waves, which are detected by a piping testing module. The collected signals are analyzed and processed in the main controller to obtain a diagnostic result regarding whether the air conditioning system is damaged. It can accurately determine the physical health status of the air conditioning system and accurately identify any physical damage, with high accuracy and a simple testing method. Simultaneously, it detects temperature parameters at the engine, piping, and cockpit to determine the air conditioning system's operational health index. By detecting the air composition in the cockpit during air conditioning operation, it can detect the cockpit safety index. It can effectively analyze the air conditioning's operating efficiency and the cockpit safety index, ensuring that aircraft that pass the inspection will not pose a danger during missions.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of aircraft detection, in particular to an aircraft air conditioning system maintenance detection device. BACKGROUND

[0002] The military aircraft air conditioner is different from the traditional household air conditioner. The aircraft flies at high altitude and basically does not need to be cooled. The air at high altitude is thin and the temperature is very low. When there is no air conditioner, the pilot generally wears heavy flight clothes to fly. The general aircraft air conditioner directly heats the heat of the engine to heat the air through the heat exchanger to guide the air into the cockpit to control the temperature of the cockpit. When cooling is needed, the air conditioner heating mode is directly turned off and the external air flow is directly cooled.

[0003] The safety of the aircraft air conditioner affects the flight safety. If the air conditioner fails during flight, on the one hand, it may cause unstable temperature change, affecting the health of the pilot, and on the other hand, it may cause the concentration of harmful gases to rise, and in an emergency, it may even cause the pilot to faint. On the other hand, during maintenance, the air conditioner is installed inside the fuselage, and the maintenance detection space is very narrow, so traditional equipment cannot be used for detection. SUMMARY

[0004] In order to solve the above problems, the present application provides an aircraft air conditioning system maintenance detection device, comprising a main controller, an engine detection module, a pipeline detection module and a cockpit detection module;

[0005] The engine detection module, the pipeline detection module and the cockpit detection module are connected to the main controller;

[0006] The aircraft air conditioner comprises an engine heat exchanger, a pipeline and a cockpit heat exchanger. The heat of the engine is transmitted to the gas in the pipeline by the engine heat exchanger, the gas in the pipeline transmits the heat to the cockpit heat exchanger, and the cockpit heat exchanger heats the cockpit, thereby realizing air conditioner heating;

[0007] The engine detection module emits sound waves, which are detected by the pipeline detection module. The collected signals are analyzed and processed in the main controller to obtain a diagnosis result of whether the air conditioner is damaged;

[0008] At the same time, the temperature parameters of the engine, the pipeline and the cockpit are detected respectively, so as to judge the working health index of the air conditioning system;

[0009] The air composition in the cockpit during the operation of the air conditioner is detected, so as to detect the safety index of the cockpit.

[0010] The engine detection module comprises an audio loading module, an engine temperature detector and an engine air pressure detector;

[0011] The pipeline detection module comprises a pipeline temperature meter, a pipeline flow meter and an audio collector;

[0012] The cockpit detection module comprises a cockpit temperature meter and a gas component detector;

[0013] The audio loading module comprises a sound wave transducer and a coupling head, the coupling head is used for coupling sound waves to the engine heat exchanger, the sound waves are transmitted along the pipeline and are collected by the audio collector; the audio collector sends the collected sound wave signals to the main controller;

[0014] The engine temperature detector is used for detecting the temperature of the engine, the pipeline temperature meter is used for detecting the temperature of the air in the pipeline, the cockpit temperature meter is used for detecting the temperature of the cockpit; the engine air pressure detector is used for detecting the pipeline air pressure at the engine, the pipeline flow meter is used for detecting the air flow rate in the pipeline, and the gas component detector is used for detecting the air gas component in the cockpit.

[0015] The engine temperature detector, the engine air pressure detector, the pipeline temperature meter, the pipeline flow meter and the cockpit temperature meter are sensors fixedly installed in the aircraft air conditioning system, have detection interfaces and are connected to the main controller after the detection interfaces are connected;

[0016] The audio loading module, the audio collector and the gas component detector are external sensors, are externally connected during detection and are removed after use.

[0017] The gas component detector comprises a gas sensor, a voltage detector and a data processor;

[0018] The gas sensor comprises a gas sensitive film, the gas sensitive film adsorbs a gas with a specific component and thus affects the resistance of the gas sensor; the voltage detector detects the partial pressure of the gas sensor and thus judges the concentration of the specific gas component;

[0019] The data processor processes the voltage change data of the voltage detector and thus judges the component and concentration of the gas.

[0020] The gas sensor comprises, from top to bottom, a gas sensitive film layer, an insulating film layer, a piezoelectric film layer and a resistance film layer, and an electrode is arranged outside the resistance film layer; each set of the gas sensitive film layer, the insulating film layer, the piezoelectric film layer, the resistance film layer and the electrode forms a sensor unit; a plurality of sensor units form the gas sensor; the voltage detector detects the voltage change of each sensor unit and sends the voltage change to the data processor;

[0021] The principle of detection is that the gas sensitive film absorbs gas to produce expansion, and the expansion will squeeze the piezoelectric film layer to produce a piezoelectric electromotive force, and further squeeze the resistance film layer to deform the resistance film layer, and the length change of the deformed resistance film layer further causes the resistance change; The resistance film layer is connected in series with a resistance with constant resistance, and when the resistance of the resistance film layer changes, the voltage division of the resistance film layer will increase;

[0022] At the same time, the piezoelectric voltage generated by the piezoelectric film layer acts on the resistance film layer, so that the resistance film layer is subjected to the voltage action of the piezoelectric film layer at the same time;

[0023] The piezoelectric film layer and the resistance film layer are only connected at the electrode, and other positions are insulated;

[0024] At the same time, the maximum voltage U1 generated by the piezoelectric film and the voltage division U2 of the resistance film layer in the non-deformation state satisfy the relationship 0.5×U2≤U1≤U2; And the voltage generated by the piezoelectric film and the voltage division direction of the resistance film layer are the same, that is, they can be added;

[0025] Through the piezoelectric film, when the pressure of deformation is received, the increase change of voltage is more obvious, and the sensitivity is higher.

[0026] The gas sensitive film layer can adsorb gas with specific components, and the gas with specific components includes CO, CO2, SO2 and O2. Each sensor unit corresponds to a gas sensitive film that adsorbs one kind of gas, and multiple gas sensitive films realize simultaneous detection of multiple gases.

[0027] The data processor obtains the voltage U of each sensor unit detected by the voltage detector as a function of time, and differentiates the voltage function with respect to time to obtain the rate of change D of the voltage with respect to time;

[0028] The data processor processes to obtain the time t0 when the absolute value of the voltage change rate D in every 10s time period is maximum, and determines the voltage change rate D corresponding to the time t0 t0 And the voltage U t0 ;

[0029] Solve the gas concentration A x =k1·D t0 +k2·U t0 ;

[0030] Where x represents CO, CO2, SO2 and O2;

[0031] Solve the driver's cabin safety index I2=k3·A O2 -k4·(A CO / A CO2 )-k5·A SO2 ;

[0032] wherein k1 to k5 are coefficients, the unit of k1 is mol / (L·V), the unit of k2 is (mol·s) / (L·V), k4 has no unit, the units of k3 and k5 are L / mol, the unit of A is mol / L, U t0 the unit of D t0 is V, the unit of A O2 , the unit of A CO , the unit of A CO2 , the unit of A SO2 respectively represent the concentration of the corresponding gas;

[0033] It is judged whether I2 is within a threshold range, and if I2 exceeds the threshold range, it indicates that the gas concentration in the cab is abnormal when the air conditioner is working, and there is a leakage of harmful gas in the combustion chamber or insufficient oxygen / carbon dioxide concentration.

[0034] The sound wave transducer of the audio loading module outputs a composite frequency sound wave, the frequency range of the sound wave covers 100 Hz to 10 MHz, the sound wave is transmitted along the pipeline, and the audio spectrum collected by the audio collector is sent to the main controller;

[0035] The main controller performs a difference between the output spectrum of the audio loading module and the collected spectrum collected by the audio collector, so as to obtain a difference spectrum F;

[0036] The difference spectrum reflects the change of the spectrum of the sound wave after passing through the air conditioner heat exchanger and the pipeline;

[0037] The main controller inputs the difference spectrum into a diagnosis model, so as to realize damage diagnosis of the pipeline heat exchanger and the like;

[0038] The engine temperature detector detects the temperature T1 of the engine, the pipeline temperature gauge is used to detect the air temperature T2 in the pipeline, and the cab temperature gauge is used to detect the temperature T3 of the cab; the engine air pressure detector is used to detect the pipeline air pressure P1 at the engine, and the pipeline flow meter is used to detect the air flow rate S1 in the pipeline;

[0039] Solving an air conditioner system working health index I1=k6·(T1-T2)+k7·(T2-T3)+k8·(P1 / S1);

[0040] k6 to k8 are coefficients, the units of k6 and k7 are 1 / °C, and the unit of k8 is s / (L·Pa);

[0041] It is judged whether I1 is within a threshold range, and if I1 exceeds the threshold range, it indicates that the air conditioner system is not healthy, and there is a blockage or a leakage.

[0042] The diagnosis model is constructed in the following manner:

[0043] Firstly, the heat exchanger and pipeline fault samples are collected, the heat exchanger and pipeline that have appeared faults are detected by sound wave emission and reception, and the corresponding standard differential spectrum is obtained;

[0044] After the differential spectrum of the samples of different faults and different positions is collected, the standard differential spectrum set is obtained; the principal component analysis method is used to analyze the relationship between each frequency and the fault type in the differential spectrum; the fault type is divided into M types, N characteristic frequencies are obtained for each fault, and MxN characteristic frequencies are obtained correspondingly;

[0045] The intensity Y of the MxN characteristic frequencies of the differential spectrum in the sample is calculated

[0046] The residual life G=r1Y1+r2Y2+…+r i Y i +…+r M×N Y M×N is constructed

[0047] Wherein r i is a coefficient, Y i is the intensity of the characteristic frequency; 1≤i≤MxN;

[0048] The value of the residual life G is valued by experience; after the value is valued, the measurement results of all samples are integrated to obtain an equation group, and all coefficients r i are solved by solving the equation group.

[0049] When actually measuring, the Y of each characteristic frequency of the actually measured differential spectrum is input into the calculation formula of the residual life G to obtain the residual life of the air conditioning system i .

[0050] The numerical range of the residual life G of the M types of faults is determined by experience, so that according to the measured result G which falls into which numerical range of the fault type, it can be determined which fault it belongs to.

[0051] The beneficial effects of the present application are:

[0052] The engine detection module of the present application emits sound waves, which are detected by the pipeline detection module, and the collected signals are analyzed and processed in the main controller to obtain the diagnosis result of whether the air conditioner is damaged; the physical health state of the air conditioning system can be accurately judged, and whether there is physical damage can be accurately judged, with high accuracy and simple detection method.

[0053] At the same time, the temperature parameters of the engine, the pipeline and the cab are detected respectively, so as to judge the working health index of the air conditioning system; by detecting the air composition in the cab when the air conditioner is working, the safety index of the cab is detected. The working efficiency of the air conditioner when working and the safety index of the cockpit can be well analyzed, so that the aircraft that passes the detection will not produce danger when performing tasks.

[0054] The engine temperature detector, the engine air pressure detector, the pipeline temperature meter, the pipeline flow meter and the cabin temperature meter are fixedly installed sensors of the aircraft air conditioning system, have a detection interface, and are connected with the main controller after connecting the detection interface; the audio loading module, the audio collector and the gas component detector are external sensors, which are externally connected during detection and are removed after use. The fixedly installed sensors can also be detected during flight of the aircraft, ensuring flight safety; only a small number of sensors need to be externally connected during detection, and the sensors can save detection resources during detection. BRIEF DESCRIPTION OF DRAWINGS

[0055] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor.

[0056] Figure Fig. 1 It is a schematic diagram of the overall architecture of the present application.

[0057] Figure Fig. 2 It is a schematic diagram of the architecture of the gas component detector of the present application.

[0058] Figure Fig. 3 It is a schematic diagram of the structure of the sensor unit of the present application. DETAILED DESCRIPTION

[0059] Embodiment 1:

[0060] Referring to Figs. 1-3 , the present application provides an aircraft air conditioning system maintenance and detection device, comprising a main controller, an engine detection module, a pipeline detection module and a cabin detection module;

[0061] The engine detection module, the pipeline detection module and the cabin detection module are all connected to the main controller.

[0062] The aircraft air conditioner comprises an engine heat exchanger, a pipeline and a cabin heat exchanger; the heat of the engine is transferred to the gas in the pipeline by the engine heat exchanger, the gas in the pipeline transfers the heat to the cabin heat exchanger, and the cabin heat exchanger heats the cabin, thereby realizing air conditioning heating;

[0063] The engine detection module emits sound waves, which are detected by the pipeline detection module, and the collected signals are analyzed and processed in the main controller to obtain a diagnosis result of whether the air conditioner is damaged;

[0064] At the same time, the temperature parameters of the engine, the pipeline and the cabin are detected respectively, so as to judge the working health index of the air conditioning system.

[0065] By detecting the air composition in the cab when the air conditioner is working, the cab safety index is detected.

[0066] The engine detection module comprises an audio loading module, an engine temperature detector, and an engine air pressure detector.

[0067] The pipeline detection module comprises a pipeline temperature meter, a pipeline flow meter, and an audio collector.

[0068] The cab detection module comprises a cab temperature meter and a gas composition detector.

[0069] The audio loading module comprises a sound wave transducer and a coupling head, the coupling head is used for coupling and loading sound waves to the engine heat exchanger, the sound waves are transmitted along the pipeline and are collected by the audio collector; the audio collector sends the collected sound wave signals to the main controller.

[0070] The engine temperature detector is used for detecting the temperature of the engine, the pipeline temperature meter is used for detecting the temperature of the air in the pipeline, and the cab temperature meter is used for detecting the temperature of the cab; the engine air pressure detector is used for detecting the pipeline air pressure at the engine, the pipeline flow meter is used for detecting the air flow rate in the pipeline, and the gas composition detector is used for detecting the air gas composition in the cab.

[0071] The engine temperature detector, the engine air pressure detector, the pipeline temperature meter, the pipeline flow meter, and the cab temperature meter are sensors fixedly installed in the aircraft air conditioning system, have detection interfaces, and are connected with the main controller after the detection interfaces are connected.

[0072] The audio loading module, the audio collector, and the gas composition detector are external sensors, are externally connected during detection, and are removed after use.

[0073] Embodiment 2

[0074] The gas composition detector comprises a gas sensor, a voltage detector, and a data processor.

[0075] The gas sensor comprises a gas sensitive film, the gas sensitive film adsorbs a gas with a specific component to affect the resistance of the gas sensor; the voltage detector detects the partial pressure of the gas sensor to determine the concentration of the specific gas component.

[0076] The data processor processes the voltage change data of the voltage detector to determine the composition and concentration of the gas.

[0077] The gas sensor comprises, from top to bottom, a gas sensitive film layer, an insulating film layer, a piezoelectric film layer, and a resistive film layer, and an electrode is arranged outside the resistive film layer; each group of the gas sensitive film layer, the insulating film layer, the piezoelectric film layer, the resistive film layer, and the electrode forms a sensor unit; a plurality of sensor units form the gas sensor; a voltage detector detects voltage changes of each sensor unit and sends the voltage changes to a data processor;

[0078] As shown in Fig. 3 , from top to bottom, there are a gas sensitive film layer, an insulating film layer, a piezoelectric film layer, and a resistive film layer, and two electrodes are arranged outside the resistive film layer; the piezoelectric film layer and the resistive film layer are conductive only at the electrodes and are insulated at other positions. Insulating layers are further arranged outside the two ends of the electrodes.

[0079] The detection principle is that the gas sensitive film absorbs gas to produce expansion, the expansion will squeeze the piezoelectric film layer to generate a piezoelectric electromotive force, further squeeze the resistive film layer to deform the resistive film layer, and the length change of the deformed resistive film layer further causes resistance change; the resistive film layer is connected in series with a resistor with a constant resistance, and when the resistance of the resistive film layer changes, the voltage division of the resistive film layer will increase.

[0080] Meanwhile, the piezoelectric voltage generated by the piezoelectric film layer acts on the resistive film layer, so that the resistive film layer is simultaneously subjected to the voltage action of the piezoelectric film layer.

[0081] The relationship between the maximum voltage U1 generated by the piezoelectric film and the voltage division U2 of the resistive film layer in the non-deformed state is 0.5×U2≤U1≤U2; and the voltage generated by the piezoelectric film and the voltage division of the resistive film layer are in the same direction, i.e., can be added.

[0082] The piezoelectric film makes the voltage increase more obvious when the pressure of deformation is received, and the sensitivity is higher.

[0083] The gas sensitive film layer can adsorb gas with specific components, and the gas with specific components includes CO, CO2, SO2, and O2; each sensor unit corresponds to a gas sensitive film that adsorbs one kind of gas, and multiple gas sensitive films realize simultaneous detection of multiple gases.

[0084] The data processor obtains a function of voltage U of each sensor unit detected by the voltage detector with respect to time, and derives the function of voltage with respect to time to obtain a rate of change D of voltage with respect to time.

[0085] The data processor processes to obtain a time t0 at which the absolute value of the rate of change D of voltage is maximum in every 10s time period, and determines the rate of change D of voltage and the voltage U corresponding to the time t0 t0 . t0 ;

[0086] Solving gas concentration A x = k1·D t0 + k2·U t0 ;

[0087] Wherein x represents CO, CO2, SO2, O2;

[0088] Solving cab safety index I2 = k3·A O2 - k4·(A CO / A CO2 - k5·A SO2 ;

[0089] Wherein k1 to k5 are coefficients, the unit of k1 is mol / (L·V), the unit of k2 is (mol·s) / (L·V), k4 has no unit, the units of k3 and k5 are L / mol, the unit of A is mol / L, the unit of U t0 is V, the unit of D t0 is V / s; A O2 , A CO , A CO2 , A SO2 respectively represent the concentration of the corresponding gas;

[0090] Judging whether I2 is within the threshold range, if I2 exceeds the threshold range, it indicates that the gas concentration in the cab is abnormal when the air conditioner is working, and there is a leakage of harmful gas from the combustion chamber or the concentration of oxygen / carbon dioxide is insufficient.

[0091] Embodiment 3:

[0092] The sound wave transducer of the audio loading module outputs a composite frequency sound wave, the frequency range of the sound wave covers 100Hz to 10MHz, the sound wave is transmitted along the pipeline, and the audio spectrum collected by the audio collector is sent to the main controller;

[0093] The output spectrum of the audio loading module and the collected spectrum collected by the audio collector are subtracted in the main controller, so as to obtain a difference spectrum F;

[0094] The difference spectrum reflects the change of the spectrum of the sound wave after passing through the air conditioner heat exchanger and the pipeline;

[0095] The main controller inputs the difference spectrum into the diagnosis model, so as to realize damage diagnosis of the pipeline heat exchanger and other positions;

[0096] The engine temperature detector detects the temperature T1 of the engine, the pipeline thermometer is used to detect the air temperature T2 in the pipeline, and the cab thermometer is used to detect the temperature T3 of the cab; the engine air pressure detector is used to detect the pipeline air pressure P1 at the engine, and the pipeline flowmeter is used to detect the air flow rate S1 in the pipeline;

[0097] Solve for the health index of the air conditioning system: I1 = k6·(T1-T2) + k7·(T2-T3) + k8·(P1 / S1);

[0098] k6 to k8 are coefficients, with k6 and k7 in units of 1 / ℃ and k8 in units of s / (L·Pa);

[0099] Determine if I1 is within the threshold range. If I1 exceeds the threshold range, it indicates that the air conditioning system is not functioning properly and there is a blockage or leak.

[0100] Example 4:

[0101] The diagnostic model is constructed as follows:

[0102] First, samples of heat exchanger and pipeline failures are collected. Then, the heat exchangers and pipelines that have failed are subjected to acoustic wave transmission and reception tests to obtain the corresponding standard difference spectrum.

[0103] After collecting the differential spectra of samples from different locations with different faults, a standard differential spectrum set is obtained. Principal component analysis is used to analyze the relationship between each frequency in the differential spectrum and the fault type. The fault types are divided into M types, and N characteristic frequencies are obtained for each fault, resulting in M×N characteristic frequencies.

[0104] The intensity Y of the M×N characteristic frequencies of the differential spectrum in the sample

[0105] Construct the remaining lifetime G = r1·Y1 + r2·Y2 + ... + r i ·Y i +……+r M×N ·Y M×N ;

[0106] Where r i Y is a coefficient. i The intensity of the characteristic frequency; 1≤i≤M×N;

[0107] The remaining lifetime G value is assigned empirically; after assignment, the measurement results of all samples are combined to obtain a system of equations, and all coefficients r are solved by solving the system of equations. i ;

[0108] In actual measurement, the Y-axis of each characteristic frequency of the measured differential spectrum will be used. i The remaining lifespan of the air conditioning system was obtained by inputting the formula for calculating the remaining lifespan G.

[0109] By empirically determining the numerical range of the remaining life G for M types of faults, we can then determine which type of fault it is based on which numerical range G falls into according to the measured results.

[0110] The above description of the embodiments has been provided for the purpose of illustration and description. It is not intended to be exhaustive or to limit the disclosure to the precise forms disclosed. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but are interchangeable with other embodiments in accordance with the disclosure, to the extent not doing so would render this disclosure unsupportable or unenforceable. In many aspects, the same element or feature can be changed or modified without departing from this disclosure. Such alterations are intended to be included within the scope of this disclosure, and all such modifications are intended to be within the scope of the disclosure.

[0111] The example embodiments are provided so that this disclosure will be thorough, and will fully convey the scope to those who are skilled in the art. Numerous specific details are set forth such as examples of specific parts, devices, and methods, to provide a thorough understanding of the embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details need not be employed, that example embodiments can be practiced in many different

[0112] Herein, professional terms are used only for the purpose of describing particular example embodiments, and are not intended to be limiting. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms "comprises" and "comprising" are inclusive and therefore specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. The method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order in which they are described. It is also to be understood that additional or alternative steps can be employed.

Claims

1. An aircraft air conditioning system maintenance detection device, comprising a main controller, an engine detection module, a pipeline detection module and a cockpit detection module; characterized in that: the engine detection module, the pipeline detection module and the cockpit detection module are all connected to the main controller; the aircraft air conditioner comprises an engine heat exchanger, a pipeline and a cockpit heat exchanger; the heat of the engine is transferred to the gas in the pipeline by the engine heat exchanger, the gas in the pipeline transfers the heat to the cockpit heat exchanger, and the cockpit heat exchanger heats the cockpit, thereby realizing air conditioning heating; the engine detection module emits sound waves, which are detected by the pipeline detection module, and the collected signals are analyzed and processed in the main controller to obtain a diagnosis result of whether the air conditioner is damaged; at the same time, the temperature parameters of the engine, the pipeline and the cockpit are detected respectively to judge the working health index of the air conditioning system; by detecting the composition of the cockpit air when the air conditioner is working, the safety index of the cockpit is detected; the engine detection module comprises an audio loading module, an engine temperature detector and an engine air pressure detector; the pipeline detection module comprises a pipeline thermometer, a pipeline flowmeter and an audio collector; the cockpit detection module comprises a cockpit thermometer and a gas composition detector; the audio loading module comprises a sound wave transducer and a coupling head, the coupling head is used to couple and load sound waves to the engine heat exchanger, and the sound waves are transmitted along the pipeline and collected by the audio collector; the audio collector sends the collected sound wave signals to the main controller; the engine temperature detector is used to detect the temperature of the engine, the pipeline thermometer is used to detect the temperature of the air in the pipeline, and the cockpit thermometer is used to detect the temperature of the cockpit; the engine air pressure detector is used to detect the pipeline air pressure at the engine, the pipeline flowmeter is used to detect the air flow rate in the pipeline, and the gas composition detector is used to detect the air composition in the cockpit.

2. The aircraft air conditioning system maintenance detection device according to claim 1, characterized in that: the engine temperature detector, the engine air pressure detector, the pipeline thermometer, the pipeline flowmeter and the cockpit thermometer are sensors fixedly installed on the aircraft air conditioning system, have detection interfaces, and are connected to the main controller after connecting the detection interfaces; the audio loading module, the audio collector and the gas composition detector are external sensors, which are externally connected during detection and are removed after use.

3. The aircraft air conditioning system maintenance detection device according to claim 1, characterized in that: the gas composition detector comprises a gas sensor, a voltage detector and a data processor; the gas sensor comprises a gas sensitive film, which adsorbs a gas of a specific component to affect the resistance of the gas sensor; the voltage detector detects the partial pressure of the gas sensor to determine the concentration of the specific gas component; the data processor processes the voltage change data of the voltage detector to determine the composition and concentration of the gas.

4. The aircraft air conditioning system maintenance detection device according to claim 3, characterized in that: The gas sensor comprises, from top to bottom, a gas sensitive film layer, an insulating film layer, a piezoelectric film layer, and a resistive film layer, and an electrode is arranged outside the resistive film layer; each group of the gas sensitive film layer, the insulating film layer, the piezoelectric film layer, the resistive film layer, and the electrode forms a sensor unit; a plurality of sensor units form the gas sensor; a voltage detector detects voltage changes of each sensor unit and sends the voltage changes to a data processor; The gas sensitive film layer can adsorb a gas with a specific component, and the gas with the specific component includes CO, CO2, SO2, and O2; each sensor unit corresponds to a gas sensitive film that adsorbs one kind of gas, and a plurality of gas sensitive films realize simultaneous detection of multiple gases.

5. The aircraft air conditioning system maintenance detection device according to claim 4, wherein: The data processor obtains a function of voltage U of each sensor unit detected by the voltage detector with respect to time, and derives the function of voltage with respect to time to obtain a rate of change D of voltage with respect to time; The data processor processes the time t0 at which the absolute value of the voltage rate of change D in each 10s time period is maximum, and determines the voltage rate of change D corresponding to the time t0 t0 and the voltage U t0 ; Solving for gas concentration A x = k1 · D t0 + k2 · U t0 ; wherein x represents CO, CO2, SO2, and O2; Solving the cab safety index I2 = k3-A O2 -k4-(A CO / A CO2 )-k5-A SO2 ; wherein k1 to k5 are coefficients, k1 has units of (mol s) / (L V), k2 has units of mol / (L V), k4 has no units, k3 and k5 have units of L / mol, A has units of mol / L, U t0 has units of V, D t0 has units of V / s; A O2 , A CO , A CO2 , A SO2 respectively represent the concentration of the corresponding gas; It is determined whether I2 is within a threshold range, and if I2 exceeds the threshold range, it indicates that the gas concentration in the cab is abnormal when the air conditioner is working, and there is a leakage of harmful gas from the combustion chamber or an insufficient concentration of oxygen or carbon dioxide.

6. The aircraft air conditioning system maintenance detection device according to claim 1, wherein: The acoustic transducer of the audio loading module outputs a composite frequency sound wave, the frequency range of the sound wave covers 100 Hz to 10 MHz, the sound wave is transmitted along the pipeline, and the audio spectrum collected by the audio collector is sent to the main controller; The main controller performs a difference between the output spectrum of the audio loading module and the collected spectrum collected by the audio collector to obtain a difference spectrum F; The difference spectrum reflects the change in the spectrum of the sound wave after passing through the air conditioner heat exchanger and the pipeline; The main controller inputs the difference spectrum into a diagnosis model to realize damage diagnosis of the pipeline and the heat exchanger; The engine temperature detector detects the temperature T1 of the engine, the pipeline temperature gauge is used to detect the air temperature T2 in the pipeline, and the cab temperature gauge is used to detect the temperature T3 of the cab; the engine air pressure detector is used to detect the pipeline air pressure P1 at the engine, and the pipeline flow meter is used to detect the air flow rate S1 in the pipeline; Solving the air conditioning system working health index I1=k6·(T1-T2)+ k7·( T2-T3)+ k8·(P1 / S1); k6 to k8 are coefficients, k6 and k7 have a unit of 1 / ℃, and k8 has a unit of L / (s·Pa); It is determined whether I1 is within a threshold range, and if I1 exceeds the threshold range, it indicates that the air conditioning system is not working healthily, and there is a blockage or a leakage.

7. The aircraft air conditioning system maintenance detection device according to claim 6, wherein: The diagnosis model is constructed in the following manner: First, samples of heat exchanger and pipeline failures are collected, and the heat exchanger and pipeline that have already failed are detected by sound wave transmission and reception to obtain corresponding standard difference spectra; Collecting the differential spectrum of samples in different faults and different positions as a standard differential spectrum set; using principal component analysis to analyze the relationship between each frequency and fault type in the differential spectrum; the fault type is divided into M types, and N characteristic frequencies are obtained for each fault, corresponding to MxN characteristic frequencies; The intensity Y of the MxN characteristic frequencies of the differential spectrum in the sample Constructing the remaining life G = r1 · Y1 + r2 · Y2 +... + r i ·Y i +... + r M×N ·Y M×N ; where r i is a coefficient, Y i is the intensity of the characteristic frequency; 1≤i≤M×N; The magnitude of the residual life G value is assigned by experience; after the assignment, the determination results of all samples are integrated to obtain an equation group, and all coefficients r are solved by solving the equation group i ; The actual measurement will be measured by the Y i The calculation formula of the input remaining life G obtains the remaining life of the air conditioning system; The numerical range of the residual life G of the M fault types is determined by experience, so according to the measured result G which falls into which numerical range of fault type, it can be determined which fault it belongs to.

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