HK1179685B - Method for detecting the performance of a crew oxygen system - Google Patents

Abstract

The present invention relates to a method and a system for detecting the performance of a crew oxygen system. The method comprising: obtaining an oxygen pressure of an oxygen cylinder of the crew oxygen system, an ambient air temperature and a cockpit temperature; generating crew oxygen messages from obtained oxygen cylinder of the crew oxygen system, the ambient air temperature and the cockpit temperature; receiving the crew oxygen messages, and determining an oxygen pressure of the oxygen cylinder under standard temperature; and determining performance of the crew oxygen system.

Description

Unit oxygen system performance detection method

Technical Field

The invention relates to a method and a system for detecting the running state of aircraft equipment, in particular to a method and a system for detecting the performance of a unit oxygen system.

Background

The flight altitude of modern aircraft is typically 7000-15000 meters. In such high altitudes, the oxygen content in the air is very low, usually with an oxygen partial pressure of only a few tens of kilopascals, and it is difficult to maintain normal breathing. Aircraft typically provide an oxygen supply by pressurizing air with an engine and then forcing it into the cabin. However, in special situations, such as decompression of the cabin or other needs, additional oxygen for breathing must be provided to the crew and passengers.

The aircraft is provided with two sets of independent oxygen systems, namely a unit oxygen system and a passenger oxygen system. The crew oxygen system uses high-pressure oxygen stored in an onboard oxygen cylinder, and is specially used for crew in a cockpit after decompression and dilution. The oxygen system of the passenger obtains oxygen through chemical reaction and supplies the oxygen to the passenger and the passenger cabin crew for use.

The crew oxygen system is very important for guaranteeing safe flight of the airplane. In the existing method for detecting the oxygen performance of the aircraft crew, the pressure of the onboard oxygen system is usually recorded manually, and when the pressure of the onboard oxygen system is lower than a certain threshold value, the oxygen cylinder is replaced. Or, the aircraft system is set to give an alarm when the pressure of the onboard oxygen system is lower than a certain threshold value, and the oxygen bottle is replaced. There are also airlines that change oxygen cylinders on a hard schedule.

However, either of the above methods increases the operating cost of the airline company. More importantly, if the airborne oxygen system has only small leakage, neither method can be found in time, and the fault cannot be eliminated in time. This results in the current troubleshooting and maintenance of crew oxygen systems being almost aftercare, so that the operational safety of the aircraft is not guaranteed. Moreover, troubleshooting due to leaks in the crew oxygen system is time consuming, which also directly results in delays and even stops of the aircraft.

Disclosure of Invention

In order to solve one or more technical problems in the prior art, according to an aspect of the present invention, a method for detecting performance of a unit oxygen system is provided, including: acquiring the oxygen pressure, the atmospheric temperature and the temperature of a cockpit of an oxygen bottle in the crew oxygen system; generating a unit oxygen message according to the acquired oxygen pressure of the oxygen cylinder, the atmospheric temperature and the temperature of the cockpit; receiving the oxygen message of the unit, and obtaining the pressure of oxygen in the oxygen cylinder at a standard temperature; and determining a performance of the crew oxygen system.

According to another aspect of the present invention, a method for generating a group oxygen packet is provided, including: acquiring the oxygen pressure, the atmospheric temperature and the temperature of a cockpit of an oxygen bottle in the crew oxygen system; and generating a unit oxygen message according to the acquired oxygen pressure of the oxygen cylinder, the atmospheric temperature and the temperature of the cockpit.

According to another aspect of the present invention, a performance detection system for a unit oxygen system is provided, which includes: a unit oxygen pressure data acquisition device; the crew oxygen message generating device generates a crew oxygen message according to the oxygen pressure of an oxygen cylinder in the crew oxygen system, the atmospheric temperature and the cockpit temperature which are acquired by the crew oxygen pressure data acquiring device, and the crew oxygen message is forwarded by the crew oxygen message transmitting device; and the crew oxygen pressure data processing device is used for receiving the crew oxygen message, obtaining the pressure of oxygen in the oxygen cylinder at the standard temperature and determining the performance of the crew oxygen system.

According to another aspect of the present invention, a performance detection system for a unit oxygen system is provided, which includes: a pressure sensor that measures an oxygen pressure of an oxygen cylinder in the crew oxygen system; the data management unit DMU or a part of the data management unit DMU of the aircraft comprehensive data system AIDS of the ACMS is used for acquiring the oxygen pressure, the atmospheric temperature and the cockpit temperature of an oxygen cylinder in the crew oxygen system and generating crew oxygen messages, and the crew oxygen messages are forwarded by an aircraft communication addressing and reporting system ACARS; and the server receives the crew oxygen message from the ACARS, obtains the pressure of oxygen in the oxygen cylinder at the standard temperature, and determines the performance of the crew oxygen system.

According to another aspect of the invention, a maintenance method for a crew oxygen system is provided, which includes acquiring oxygen pressure, atmospheric temperature and cockpit temperature of an oxygen cylinder in the crew oxygen system; generating a unit oxygen message according to the acquired oxygen pressure of the oxygen cylinder, the atmospheric temperature and the temperature of the cockpit; receiving the oxygen message of the unit, and obtaining the pressure of oxygen in the oxygen cylinder at a standard temperature; determining whether performance of the crew oxygen system is degraded; and scheduling maintenance of the crew oxygen system in response to degradation of performance of the crew oxygen system.

Drawings

Preferred embodiments of the present invention will now be described in further detail with reference to the accompanying drawings, in which:

FIG. 1 is a schematic diagram of a configuration of an aircraft crew oxygen system according to one embodiment of the present disclosure;

FIG. 2 is a schematic illustration of an aircraft crew oxygen system bypass configuration according to one embodiment of the present disclosure;

FIG. 3 is a schematic diagram of a circuit configuration of a pressure sensor according to one embodiment of the present invention;

FIG. 4 is a schematic diagram of a crew oxygen performance detection system according to one embodiment of the present invention;

FIG. 5 is a flow diagram of generating a crew oxygen message according to one embodiment of the present invention;

FIG. 6 is a schematic diagram of an example crew oxygen performance detection system according to one embodiment of the present disclosure;

FIG. 7 is a schematic representation of a crew oxygen system performance profile;

FIG. 8 is a flow diagram of a method of detecting crew oxygen system performance according to one embodiment of the present disclosure;

FIG. 9 is a graphical illustration of normalized pressure of oxygen for a crew oxygen system oxygen cylinder versus measurement time in accordance with an embodiment of the present invention;

FIG. 10 is a graphical illustration of normalized pressure of oxygen for a crew oxygen system oxygen cylinder versus measurement time in accordance with an embodiment of the present invention;

FIG. 11 is a schematic diagram of a 24 hour 3 day rolling average leak rate of the crew oxygen system versus measurement time according to the embodiment of FIG. 10; and

FIG. 12 is a flow chart of a method of servicing an aircraft crew oxygen system in accordance with an embodiment of the present invention.

Detailed Description

FIG. 1 is a schematic diagram of a configuration of an aircraft crew oxygen system according to one embodiment of the present invention. As shown in fig. 1, the crew oxygen system 100 includes an oxygen cylinder 101, a pressure reducing regulator 102, and an oxygen supply line 103. The oxygen cylinder 101 stores high-pressure oxygen therein. The oxygen cylinder 101 is connected to a pressure reducing regulator 102. The high pressure oxygen is converted to low pressure oxygen through a pressure reducing regulator 102. Low pressure oxygen is supplied to the driver mask 110, the co-driver mask 130, the observer mask 120 and the second observer mask 140 via the oxygen supply line 103. In the figure, the mask 110, the co-driver mask 130 and the second observer mask 140 also show a storage box for storing an oxygen mask (the oxygen mask is placed in the storage box); while the observer mask in the figure shows a separate observer mask 120 and observer mask storage box 121. The oxygen cylinder 101 is also connected to a frangible disc 105 by a release tube 104. When the pressure in the oxygen cylinder is too great, the frangible disks 105 break and oxygen will flow out of the cabin.

FIG. 2 is a schematic diagram of an aircraft crew oxygen system bypass configuration according to one embodiment of the present invention. As shown in fig. 2, the branch 200 of the overall crew oxygen system may be divided into a high pressure section and a low pressure section. After the high-pressure oxygen stored in the oxygen cylinder 101 passes through the splitter 210, one branch is connected with the release pipe and is connected to the outside of the cabin through a fragile disc to prevent overpressure. The other branch is connected to a reduced-pressure splitter 220. Unlike the pressure reducing regulator shown in fig. 1, the pressure reducing splitter 220 simultaneously reduces pressure and splits two functions. After the pressure reduction branch, the two branches are connected to an oxygen supply pipeline to respectively supply oxygen to oxygen masks of the crew members; the other branch is connected to a test port for testing.

According to an embodiment of the present invention, a pressure sensor, such as the pressure sensor 230, is installed on the pressure reducing regulator or the pressure reducing splitter to measure the oxygen pressure in the oxygen cylinder. According to an embodiment of the present invention, the pressure sensor 230 may also be mounted to one branch of the splitter 210 or one branch of the oxygen cylinder. In general, the pressure sensor 230 may be installed at any position of the hyperbaric section to measure the oxygen pressure in the oxygen cylinder.

Fig. 3 is a schematic diagram of a circuit configuration of a pressure sensor according to an embodiment of the present invention. As shown, pressure sensor 300 includes a housing 310 for protecting internal circuit structures. According to one embodiment of the present invention, the pressure sensor 300 is a piezoelectric crystal type sensor including a piezoelectric crystal 320 connected between a power source terminal Va and ground. Oxygen pressure acts on the piezoelectric crystal. The piezoelectric crystal converts the oxygen pressure into an electrical signal. The electrical signal representative of the oxygen pressure is transmitted to an aircraft data system. Different types of Aircraft may have different Aircraft data systems, such as the Aircraft Condition Monitoring System (ACMS) from the air passenger company or the Aircraft health Monitoring System (AHM) from the Boeing company.

FIG. 4 is a schematic diagram of a crew oxygen performance detection system according to one embodiment of the present invention. As shown in the figure, the crew oxygen performance detection system 400 includes a crew oxygen pressure data obtaining device 401, a crew oxygen message generating device 402, a crew oxygen message transmitting device 403, and a crew oxygen data processing device 404.

The crew oxygen pressure data acquiring device 401 is configured to acquire oxygen pressure data in an oxygen cylinder in the crew oxygen system. The aircraft crew oxygen system and the pressure sensor thereof of the embodiment shown in fig. 1-3 may be applied to the crew oxygen pressure data obtaining device 401 in the present embodiment to obtain the required crew oxygen pressure data. The crew oxygen pressure data acquiring device 401 may also acquire oxygen pressure data in an oxygen cylinder in the crew oxygen system in other manners. Due to the importance of crew oxygen for flight safety, almost every aircraft will automatically acquire crew oxygen pressure data. That is, each of the existing aircrafts is equipped with its own crew oxygen pressure data acquisition device. However, according to an embodiment of the present invention, the crew oxygen pressure data acquisition device 401 of the present invention may be any one of such crew oxygen pressure data acquisition devices.

As aircraft systems become more complex, aircraft data systems have evolved significantly. Such as the ACMS system of airbus and the AHM system of boeing corporation. In addition, a Centralized Fault Display System (CFDS) has been developed. One feature of these systems is that they can be based on real-time monitored data. And when a certain trigger condition is met, automatically generating a message containing specific data. The crew oxygen message generating device 402 in this embodiment may be these systems or part of these systems.

Taking the ACMS System of airbus as an example, the AHM System of boeing corporation can be compared, and the ACMS System includes flight Integrated Data System (AIDS). And a Data Management Unit (DMU) is the core of the AIDS system. The DMU has two very important functions:

-collecting, processing and recording a number of parameters on board the aircraft, including data from black boxes. These parameters are stored in the DMU's internal memory or in an external Recorder, such as the AIDS Digital Recorder (DAR);

-generating a system message, which is triggered when the state or system parameters of the aircraft meet the triggering conditions of the message. These messages are stored in the non-volatile memory of the DMU.

According to an embodiment of the present invention, the crew oxygen message generating device 402 is a DMU or a part of a DMU. The crew oxygen message generating device 402 obtains the oxygen pressure data in the crew oxygen system from the crew oxygen pressure data obtaining device 401.

Since the oxygen pressure of the oxygen cylinder in the crew oxygen system is temperature dependent, the oxygen pressure must be obtained simultaneously with the temperature of the oxygen in the oxygen cylinder. However, a temperature sensor is not generally installed in the oxygen system. Therefore, it is necessary to calculate the temperature of the oxygen in the oxygen cylinder from other temperatures that can be measured. According to one embodiment of the invention, a temperature sensor measuring the oxygen temperature may be added to the oxygen system of the unit.

In view of the location of the oxygen cylinder in the crew oxygen system, according to one embodiment of the present invention, the following formula may be used to derive the temperature of the oxygen in the oxygen cylinder:

wherein Tat represents the atmospheric temperature or the outside temperature, Tc represents the cabin temperature, k₁And k₂Is a tuning parameter and satisfies k₁+k₂And (2). According to one embodiment of the present invention, k₁>k₂. That is, the oxygen temperature T and the atmospheric temperature Tat are correlated with the cabin temperature Tc, and the influence of the atmospheric temperature is greater. Of course, other averaging equations may be used to calculate the oxygen temperature.

According to one embodiment of the present invention, k₁=k₂. That is, equation (1) can be rewritten as:

where k is an adjustment parameter. According to one example of the invention, k is a number that is relatively close to the value 1. k. k is a radical of₁And k₂Can be obtained by actual measurement or by statistical analysis.

According to one embodiment of the present invention, k =1 may be taken. Equation (2) can be rewritten as:

although the oxygen temperature thus derived may not be as accurate as equations (1) and (2), it is sufficient for the embodiments of the present invention to detect crew oxygen system performance.

As described above, many flight parameters may be automatically obtained by an aircraft data system, such as ACMS from the air passenger company or AHM from the Boeing company. These parameters include the atmospheric or outboard temperature Tat and the cabin temperature Tc. And under the condition that the triggering condition is met, when the oxygen pressure data of the oxygen cylinder in the crew oxygen system is obtained, the atmospheric temperature or the outside temperature Tat and the cockpit temperature Tc at the moment are obtained at the same time, and a crew oxygen message is generated.

The crew oxygen message is transmitted to the crew oxygen data processing device 404 through the crew oxygen message transmitting device in real time or at a specific time. According to one embodiment of the present invention, the crew oxygen message transmitting device includes an aircraft portion 403 and a ground portion 410, which enable aircraft-to-ground communication. An example of a crew oxygen messaging device is the Aircraft Communication Addressing and Reporting System (ACARS). ACARS is a digital data link system for transmitting messages (i.e., short messages) between an aircraft and a ground station via radio or satellite, and provides services for large-traffic data communication between the air and ground of an airline company, thereby realizing the exchange of various information.

The ACARS system consists of an avionics computer called ACARS Management Unit (MU) and a Control Display Unit (CDU). The MU is used to transmit and receive VHF radio digital messages from the ground. On the ground, the ACARS system consists of a network of ground stations 410 with radio transceiver mechanisms, which can receive or transmit messages (data chain messages). These ground stations are typically owned by various service providers that distribute received messages to servers of different airlines on the network.

On one hand, the ACARS can enable a flying airplane to automatically provide real-time data information such as flying dynamic and engine parameters to an airline ground workstation without intervention of crew members, and can also transmit other various information to the ground, so that an airline operation control center obtains real-time and uninterrupted large amount of flight data and related information of the airplane on an application system of the airline operation control center, the dynamic of the airplane of the airline company is mastered in time, the real-time monitoring of the airplane is realized, and the requirements of management of various related departments such as aviation service, operation and airplane service are met; on the other hand, the ground can provide various services such as meteorological information, airway conditions, air emergency fault troubleshooting measures and the like for the airplane flying in the air, and the flight safety guarantee capability and the service level for passengers are improved. Under the conditions that the common VHF ground-air communication channel is increasingly saturated, the information transmission quantity is small, and the speed is low, the bidirectional data communication system can remarkably improve and enhance the ground-air communication guarantee capability.

According to an embodiment of the present invention, the crew oxygen message transmission device may also be a communication device or system based on an Aviation Telecommunication Network (ATN).

According to one embodiment of the invention, the crew oxygen messaging device may be a solid state storage device. The crew oxygen messages are stored in the solid-state storage device. The transmission of the crew oxygen messages can also be realized by transmitting the solid-state storage device.

The crew oxygen data processing device 404 receives the crew oxygen message from the crew oxygen message transmitting device 403. Crew oxygen data processing device 404 may be a server of an airline according to one embodiment of the present invention. According to one embodiment of the invention, the server receives crew oxygen messages from an aircraft via ACARS or ATN.

The crew oxygen data processing device 404 performs message decoding by a device such as an ACARS message decoder to obtain data, and stores the data in the data server.

In order to improve the accuracy of the method for detecting the performance of the crew oxygen system, the oxygen pressure, the atmospheric temperature and the cockpit temperature of the oxygen cylinder of the crew oxygen system need to be obtained as accurately as possible, so that a more accurate crew oxygen message is generated.

Fig. 5 is a flowchart of a method for generating a crew oxygen message according to an embodiment of the present invention. In the generate crew oxygen message method 500 shown in fig. 5, the aircraft takes off at step 510. During or after the aircraft takes off, oxygen pressure data for the oxygen cylinders in the crew oxygen system 1 minute before taking off is obtained 521. At step 522, the atmospheric temperature and cabin temperature are acquired 1 minute before takeoff. Although described separately in steps 521 and 522, they may be performed simultaneously as one step, or step 522 may be performed prior to step 521. The following acquisition procedure is the same.

The operating data of the aircraft, including the oxygen pressure data of the oxygen cylinders in the crew oxygen system, the atmospheric temperature and the cockpit temperature, can be measured in real time and stored in the data cache. When the takeoff is set to be triggered by the trigger condition, the related data of 1 minute before the takeoff can be acquired from the data cache. According to an embodiment of the invention, other trigger conditions, such as a timer, can be adopted to directly acquire oxygen pressure data, atmospheric temperature and cockpit temperature of an oxygen bottle in the crew oxygen system 1 minute before takeoff in real time.

According to one embodiment of the invention, at steps 521 and 522, after acquiring data 1 minute before takeoff, crew oxygen pressure data, atmospheric temperature, and cabin temperature are acquired 30 seconds apart, and then crew oxygen pressure data, atmospheric temperature, and cabin temperature are acquired 30 seconds apart. That is, 1 minute before takeoff, 30 seconds before takeoff, and 3 sets of crew oxygen pressure data, atmospheric temperature, and cabin temperature at takeoff were acquired. And taking the average value or the median value of the 3-time acquisition as data for generating the oxygen message of the unit. The acquired data of the oxygen message of the unit is more accurate.

According to one embodiment of the invention, the oxygen message of the unit can be generated directly according to the oxygen pressure data obtained before (or during) takeoff, the atmospheric temperature and the temperature of the cockpit. After step 522, the process proceeds directly to step 560 to generate a crew oxygen message.

The unit oxygen pressure and temperature data obtained before takeoff (or during takeoff) and the data obtained after landing can be combined together to generate a unit oxygen message. Or generating an incomplete message after acquiring the oxygen pressure and temperature data of the unit before takeoff, and storing the incomplete message in a memory; and after the oxygen pressure and temperature data of the unit after taking off are obtained, the message is completely supplemented.

As shown in the embodiment of fig. 10, the oxygen pressure data, the atmospheric temperature, and the cabin temperature obtained before (or at) takeoff, or incomplete messages including these data, are stored in the memory of the flight data system in step 530. At step 540, the aircraft lands. At step 551, oxygen pressure data of an oxygen cylinder in the crew oxygen system 1 hour after the descent is obtained, and at step 552, the atmospheric temperature and the cockpit temperature 1 hour after the descent are obtained. The time after the drop is the trigger condition for steps 551 and 552 to trigger the acquisition of the data. In step 560, the data obtained before takeoff (or during takeoff) and the data obtained after landing are merged together to generate a complete unit oxygen message.

According to one embodiment of the invention, after acquiring the oxygen pressure data, the atmospheric temperature and the cabin temperature 1 hour after the descent, the oxygen pressure data, the atmospheric temperature and the cabin temperature 1 hour after the descent and 30 seconds apart are acquired, and then the oxygen pressure data, the atmospheric temperature and the cabin temperature 1 hour after the descent and 60 seconds apart are acquired. That is, 3 sets of oxygen pressure data, atmospheric temperature, and cabin temperature at 1 hour, zero 30 seconds at 1 hour, and zero 60 seconds at 1 hour after the descent were acquired. And taking the average value or the median of the 3 acquired data as data for generating the oxygen message of the unit. For steps 551 and 552, the crew oxygen pressure data and temperature data may be obtained at other times, while ensuring that the temperature of the aircraft is consistent with the ambient temperature, while eliminating the effects of flight.

According to one embodiment of the invention, if the aircraft takes off again less than 1 hour after landing, the oxygen pressure data, the atmospheric temperature and the cockpit temperature before (or at) taking off again are acquired instead of the data acquired 1 hour after landing. Of course, this also includes the manner in which the median or average is taken over a number of measurements.

FIG. 6 is a schematic diagram of an example crew oxygen performance detection system, according to an embodiment of the present invention. As shown in fig. 6, crew oxygen performance detection system 600 includes a DMU on an aircraft. The DMU acquires the oxygen pressure data of the unit before takeoff (during takeoff) and after landing, the atmospheric temperature and the temperature of the cockpit, and generates an oxygen message of the unit. The DMU sends the crew oxygen message to the ACARS onboard management unit MU. The MU directly sends the oxygen message of the unit to a service provider of the ACARS ground station through the very high frequency radio communication; or, the communication satellite transmits the crew oxygen message to the service provider of the ground station through the communication with the communication satellite. And the ground service provider forwards the received crew oxygen message to a server of a corresponding airline company. And the unit oxygen data contained in the unit oxygen message is processed on the server. The user can check the oxygen condition of the unit by logging in the server, so that the performance of the oxygen system of the unit is detected.

The system for detecting the oxygen performance of the aircraft crew realizes automatic detection of the oxygen performance of the aircraft crew on the aircraft, thereby avoiding the cost of manual recording and avoiding the problem caused by error recording or missing recording possibly occurring in manual recording.

FIG. 7 is a schematic representation of a crew oxygen system performance profile. All oxygen systems have a small amount of leakage, so that at a given temperature, a pressure differential of Δ P occurs at different times. And the air leakage rate can be P_LAnd = Δ P/t. When air leakage rate P_LWhen the stability is achieved, the performance of the oxygen system of the unit is in a stable period; when air leakage rate P_LWhen the temperature is gradually increased, the performance of the oxygen system of the unit enters a decay period; when air leakage rate P_LGreater than a threshold value P_LgIn time, the performance of the crew oxygen system enters a failure period, and a failure may occur. The influence is beneficial to flight safety, and the non-planned maintenance is easy to generate, so that the flight delay and the flight stop are caused. There is no means in the prior art to detect whether a crew oxygen system enters a decay period. Such detection may be accomplished according to one embodiment of the present invention.

The decay period detection has the following advantages: first, the probability of failure is still very low when the oxygen system of the unit is in the decay period. If the airplane is selected to be overhauled at the moment, the flight safety can be guaranteed. Second, when it is detected that the crew oxygen system is in the decay phase, the airline can schedule maintenance of the aircraft in a timely manner, thereby avoiding unscheduled maintenance and reducing delays in the aircraft. And avoids the waste of maintenance cost caused by replacing the oxygen cylinder according to hard time limit or performing maintenance. Of course, embodiments of the present invention may also be applicable to the detection of a period of failure.

FIG. 8 is a flow chart of a method of detecting crew oxygen system performance according to one embodiment of the present invention. In a method 800 of detecting performance of a crew oxygen system as shown in fig. 8, oxygen pressure data, atmospheric temperature, and cabin temperature of oxygen cylinders in the crew oxygen system are obtained at step 810. In step 820, a crew oxygen message is generated according to the acquired oxygen pressure data of the oxygen cylinder in the crew oxygen system, the atmospheric temperature and the cockpit temperature. In step 830, the generated crew oxygen message is transmitted to a server for processing the crew oxygen message. In step 840, the server converts the oxygen pressure of the oxygen cylinders in the crew oxygen system to a standard state pressure at a standard temperature based on the atmospheric temperature and the cockpit temperature. The standard temperature may be 20 ℃. Of course, other temperatures may be used.

After the oxygen temperature is obtained, the measured pressures of the oxygen of the unit at different temperatures can be converted into standard state pressures at standard temperatures for comparison and calculation of the leakage rate. The standard state pressure can be calculated by the following formula:

wherein P is_sIs the pressure of the standard state, T_sIs the standard temperature, P is the measured oxygen pressure, and T is the temperature of the oxygen at the time of measurement. The standard temperature may be 20 ℃. Of course, other temperatures may be used.

As shown in FIG. 8, in step 850, multiple sets of normalized pressure data of the unit oxygen system at different times are obtained in the manner of step 810 and 840. After a plurality of sets of standard state pressures of oxygen in oxygen bottles in the crew oxygen system at different times at standard temperatures are obtained, the performance of the crew oxygen system can be determined by processing and evaluating the data.

At step 860, the sets of normalized pressure data at different times are analyzed to determine if the crew oxygen system performance is degraded. Alternatively, in step 870, multiple sets of standard state pressure data at different times are compared as one sample to another sample of another set of standard state pressure data for the same type of aircraft to determine if the crew oxygen system performance is degraded.

According to one embodiment of the invention, the segment leakage rate is used to determine if the performance of the crew oxygen system is deteriorating. The section leakage rate of the oxygen system of the unit can be calculated by adopting the following formula:

wherein, t₁Time of flight, t₂Time of flight descent, P_s1Is the unit oxygen standard state pressure P when the airplane takes off_s2The oxygen standard state pressure of the aircraft after landing is obtained. Therefore, the oxygen standard state pressure change delta P of the unit can be changed according to the oxygen standard state pressure before taking off and after landing_sTo determine the performance of the crew oxygen system. For example, if Δ P_s=P_s1-P_s2Above 100PSI, the performance of the onboard oxygen system deteriorates.

The performance of the crew oxygen system can also be determined according to the flight leakage rate. For example, if the leg leakage rateAbove 48 PSI/day, the performance of the onboard oxygen system deteriorates.

And according to the calculated section leakage rate, estimating the pressure reading of the oxygen system of the unit at a certain temperature. The situation that the oxygen cylinder is not changed in an planned way before flying due to large temperature change of the airplane and the refrigerator after flying in winter can be greatly reduced.

According to one embodiment of the invention, the oxygen pressure P is normalized by the oxygen pressure of the crew oxygen system_sAnd the installation time t of the oxygen cylinder of the oxygen system of the unit_oThe performance of the crew oxygen system is determined by detecting the slope of the fitted curve.

P_sAnd t_oThe relationship conforms to the following formula:

P_s=β1+β2*t_o+μ （6）

wherein, P_sIs the pressure of the standard state, t_oIs the installation time of the oxygen cylinder of the oxygen system of the unit, beta 1 is an intercept term which is related to the flight time; beta 2 is obliqueA rate term, which reflects the gas tightness of the oxygen system; and μ is a random interference term that reflects P_sAnd t_oThe uncertainty in between.

t_oThe mean value of (d) can be expressed as follows:

where n represents the number of sampled data points involved in the calculation.

P_sThe mean value of (d) can be expressed as follows:

where n represents the number of sampled data points involved in the calculation.

According to equations (6) to (8), β 2 can be calculated using the following equation

Beta 2 is a negative value. A smaller value of β 2 indicates a poorer tightness of the crew oxygen system. The performance of the crew oxygen system can be derived by detecting the change in β 2, i.e., the slope term. By comparing the slope term β 2 between different aircraft, the performance of the crew oxygen systems of these aircraft can also be understood.

When the slope detection method is adopted to detect the performance of the oxygen system of the unit, events such as oxygen bottle replacement or oxygenation are preferably not carried out in the time represented by the data points participating in calculation.

According to one embodiment of the invention, the condition that the performance of the crew oxygen system is poor is determined by a method of Independent Sample T Test (Independent Sample Test) of the leakage rate.

Because the time interval of the flight period is short, the possible change of the system pressure is small, the system pressure is easily influenced by the fitting precision of the external temperature and the detection precision of the pressure sensor, and the standard state pressure fluctuation obtained by calculation is large sometimes. In order to reduce the influence of the accuracy of the outside temperature and the accuracy of the pressure sensor, according to one embodiment of the invention, the air section leakage rate is not adopted, and two points with the interval of more than 24 hours are adopted for pressure comparison, namely the leakage rate P with the interval of 24 hours is adopted_L24. Of course, other time intervals, such as time intervals greater than 12 or 36 hours, may also be used. At the same time, in order to eliminate the data dead pixel shadow caused by the sampling problemSound, to P_L24A3 day rolling average may be used, meaning that all P's within 3 days are calculated_L24Average value of (a). The 3 days are only given as examples, but other days, such as 2-4 days, may of course also be used. Depending on the situation of the data.

According to one embodiment of the invention, the 24-hour 3-day rolling average leakage rate P reflecting the performance characteristics of the crew oxygen system is calculated by using the following formula_L-avg24，：

Where n represents the number of data points in 3 days.

According to one embodiment of the present invention, if it is desired to determine whether a change in the oxygen performance of a crew member occurs over a certain period of time, the data over the set of time periods may be taken as a set of samples; at the same time, another set of data for the same type of aircraft is taken as a set of samples. Two are combinedP of group data samples_L-avg24And comparing, and determining whether the two groups of data have significant changes according to statistical probability so as to judge the time period and the degree of the performance deterioration of the oxygen system of the unit.

According to one embodiment of the present invention, first, P is calculated for 2 sets of data_L-avg24And calculate P_L-avg24The variance. Assume S1²Is a first group P_L-avg24Variance of (including n items of data), S2²Is a second group P_L-avg24(containing m data) variance. Due to S1²/S2²The F value should be determined by finding the F distribution table by difference, subject to the F (n-1, m-1) distribution. And whether the two groups of data have obvious difference can be judged according to the F value. Two sets of data can be considered to be significantly different if the probability of the two sets of data belonging to the same distribution is examined to be less than 2.5%.

Other independent sample T-test methods may also be used to determine if there is a significant difference between the two sets of data. If this difference is significant, it indicates that there is a significant change in the performance of the crew oxygen system. If the performance of the oxygen system of the unit is obviously changed, which group of data represents the performance deterioration of the oxygen system of the unit can be easily judged according to the average value of the permeability.

The independent template test method for average leakage rate can use data of the same airplane in different time periods, and can also use data of the same type of airplane in different time periods. Therefore, this method is flexible. Moreover, the checking mode is not limited by whether the oxygen bottle is replaced or not and oxygenation is carried out, and the method can be used for comparing whether the performance of the unit oxygen system is obviously changed or not before and after the oxygen bottle is replaced and oxygenation is carried out.

The following examples are provided to illustrate how the method of the present invention can be used to detect whether a significant change in the performance of a crew oxygen system has occurred.

Fig. 9 is a graph illustrating the normalized pressure of oxygen in the oxygen cylinder of the crew oxygen system versus the measurement time, according to an embodiment of the present invention. In fig. 9, the broken lines represent the standard state pressures of the actual sampling conversion, and the straight lines represent the lines regressing from the standard state pressures of oxygen and the measurement time, respectively. The formula (9) of the slope detection method is adopted for detection, and the leakage rate of the oxygen system of the unit is too large, the slope is-0.024929, and the slope is much smaller than the normal slope which is lower than-0.015. This reflects the degradation of the crew oxygen system and the decay period has been entered.

Fig. 10 is a graph illustrating the normalized pressure of oxygen in the oxygen cylinder of the crew oxygen system versus the measurement time, according to one embodiment of the present invention. The figure shows a process for replacing a crew oxygen system oxygen cylinder at a time. The dots in FIG. 10 represent the normalized pressure for the actual sample transition. FIG. 11 is a graph illustrating the 24 hour 3 day rolling average leak rate of the crew oxygen system versus the time of measurement according to the embodiment of FIG. 10. Two sets of data before and after replacing the oxygen cylinder are used as two samples, and an independent sample T test method is adopted to test whether the two samples are the same. The calculation shows that the probability of the two sets of data being identical before and after the replacement of the oxygen cylinder is zero. The performance of the oxygen system of the unit is poor, and the average leakage rate is 2 times of the original average leakage rate. The performance of the crew oxygen system has entered the decay period.

As can be seen from the embodiments of fig. 9 to fig. 11, the method for detecting the performance of the crew oxygen system according to the present invention may obtain whether the performance of the crew oxygen system is deteriorated or not by processing and analyzing the crew oxygen system oxygen pressure data and temperature data obtained in the crew oxygen message, and by calculating a slope or performing an independent sample T test, and the like, and enter a performance decay period or a failure period of the crew oxygen system.

FIG. 12 is a flow chart of a method of servicing an aircraft crew oxygen system in accordance with an embodiment of the present invention. In a method 1200 of aircraft crew oxygen system maintenance as shown in fig. 12, oxygen pressure data, atmospheric temperature, and cockpit temperature of oxygen cylinders in the crew oxygen system are obtained at step 1210. At step 1220, a crew oxygen message is generated based on the acquired oxygen pressure data of the oxygen cylinders in the crew oxygen system, the atmospheric temperature, and the cockpit temperature. In step 1230, the generated crew oxygen message is transmitted to the server. In step 1240, the server processes the crew oxygen messages to obtain the standard state pressure of the oxygen cylinders in the crew oxygen system at the oxygen standard temperature. In step 1250, it is determined whether the crew oxygen system performance is degraded based on the sets of standard pressure data at different times. In step 1260, if the performance of the crew oxygen system is poor, a suitable time is scheduled for maintenance of the crew oxygen system.

The invention does not need manual recording, and saves human resources. In addition, the pressure and the oxygen leakage rate in the oxygen standard state are obtained through the oxygen message, so that the performance of the airborne oxygen system is judged, the performance of the airborne oxygen system can be repaired before the performance of the airborne oxygen system enters the failure period, failure diagnosis is accelerated, and troubleshooting time is shortened, so that the service time of the airborne oxygen system is prolonged, the operation cost of an airline company is reduced, the personal safety problem of passengers on an airplane caused by sudden large-scale leakage of the airborne oxygen system can be prevented, and the operation safety of the airplane is improved. The method can predict the remaining service time of the airborne oxygen system through the leakage rate, thereby greatly prolonging the service time and reducing the maintenance cost of the airplane.

The above embodiments are provided only for illustrating the present invention and not for limiting the present invention, and those skilled in the art can make various changes and modifications without departing from the scope of the present invention, and therefore, all equivalent technical solutions should fall within the scope of the present invention.

Claims (10)

1. The method for detecting the performance of the oxygen on board the aircraft is characterized by comprising the following steps:

acquiring the running state of an airborne oxygen system of the aircraft flying once through a trigger and forming an ACARS oxygen message;

transmitting the ACARS oxygen message to a ground workstation through an air-ground data chain system;

the ground workstation decodes the ACARS oxygen message through an ACARS message decoder to obtain data, obtains a pressure value Ps of the airborne oxygen system in a standard state through operation, and stores the pressure value Ps into a data server;

and judging the performance of the airborne oxygen according to the pressure value Ps of the airborne oxygen system in the standard state.

2. The method for detecting the performance of oxygen on board an aircraft of claim 1, wherein: the running state of the onboard oxygen system comprises the running state of the onboard oxygen system when the engine is started; the method also comprises the operation state of the onboard oxygen system when the aircraft engine stops 3600s or the operation state of the onboard oxygen system when the engine is restarted when the aircraft engine stops for less than 3600 s.

3. The method for detecting the performance of oxygen on board an aircraft of claim 2, wherein: the method for collecting the running state of the airborne oxygen when the aircraft engine is started is to collect the running state of the airborne oxygen 60 seconds before the aircraft engine is started, wherein the collection is carried out once every 30 seconds and 3 times.

4. The method for detecting the performance of oxygen on board an aircraft of claim 3, wherein: the method for acquiring the running state of the airborne oxygen when the aircraft engine stops 3600s is to acquire the running state of the aircraft engine when the aircraft engine stops 3600s after the aircraft lands, wherein the acquisition is carried out once every 30s and 3 times.

5. The method for detecting the performance of oxygen on board an aircraft of claim 4, wherein: the data obtained by decoding by the ACARS message decoder comprises outdoor temperature, passenger cabin temperature and oxygen pressure which are obtained by acquiring for three times 60 seconds before the start of the aircraft engine and 3600 seconds after the aircraft lands.

6. The method for detecting the performance of the oxygen on board the aircraft as claimed in claim 5, wherein the method for detecting the pressure value Ps of the on-board oxygen system under the standard state comprises the following steps:

obtaining a corrected temperature T through a formula (Ti + To)/2, wherein Ti is a median of outdoor temperatures obtained by three times of acquisition, and To is a median of passenger cabin temperatures obtained by three times of acquisition;

obtaining a pressure value Ps of the airborne oxygen system in a standard state by a formula PV/T (pressure/volume), wherein P is pressure, V is volume, T is corrected temperature, n is mole number, and the volume V is kept unchanged, and obtaining a formula Ps (PTs/T), wherein Ts is standard temperature.

7. The method for detecting the performance of oxygen on board an aircraft of claim 6, wherein: the method for judging the performance of the onboard oxygen according to the pressure value Ps of the onboard oxygen system in the standard state is characterized in that the pressure value Ps1 in the oxygen standard state when the aircraft engine is started is compared with the pressure value Ps2 in the oxygen standard state when the aircraft engine is stopped 3600s to obtain the pressure difference delta Ps1-Ps2, and then the performance of the onboard oxygen is judged according to the pressure difference delta Ps; or comparing the pressure value Ps1 in the oxygen standard state when the aircraft engine is started with the pressure value Ps2 in the oxygen standard state when the aircraft engine is restarted when the aircraft engine is stopped for less than 3600s to obtain the pressure difference deltaPs 1-Ps2, and judging the onboard oxygen performance according to the pressure difference deltaPs.

8. The method of claim 7, wherein: the method for judging the performance of the airborne oxygen according to the pressure difference deltaPs is characterized in that when the pressure difference (Ps1-Ps2) > 100PSI, the performance of the airborne oxygen is abnormal; on the contrary, the airborne oxygen performance is normal.

9. The method for detecting the performance of oxygen on board an aircraft of claim 6, wherein: the method for judging the performance of the onboard oxygen by the pressure value Ps of the onboard oxygen system in the standard state is characterized in that the pressure value Ps1 in the oxygen standard state when the aircraft engine is started is compared with the pressure value Ps2 in the oxygen standard state when the aircraft engine is stopped 3600s to obtain a pressure difference delta Ps1-Ps2, and then an oxygen leakage rate is obtained by a formula (Ps1-Ps2)/(t2-t1), wherein t1 is the time when the aircraft engine is started, t2 is the time when the aircraft engine is stopped 3600s, and the performance of the onboard oxygen is judged according to the oxygen leakage rate; or comparing a pressure value Ps1 in an oxygen standard state when the aircraft engine is started with a pressure value Ps2 in the oxygen standard state when the aircraft engine is stopped for less than 3600s and restarting the engine to obtain a pressure difference delta Ps1-Ps2, and obtaining an oxygen leakage rate through a formula (Ps1-Ps2)/(t2-t1), wherein t1 is the time when the aircraft engine is started, t2 is the time when the aircraft engine is stopped for less than 3600s and carrying out judgment on the on-board oxygen performance according to the oxygen leakage rate.

10. The method of claim 9 for detecting the performance of oxygen onboard an aircraft, wherein: the method for judging the performance of the onboard oxygen according to the oxygen leakage rate is characterized in that when the oxygen leakage rate is more than 48 PSI/day, the performance of the onboard oxygen is abnormal; on the contrary, the airborne oxygen performance is normal.