A method for testing the flame retardancy of airborne electronic equipment for aviation

Abstract

The present invention relates to the technical field of aircraft component and system testing, and discloses a method for testing the flame retardancy of airborne electronic equipment for aviation. The electronic equipment to be tested is fixed on a test rack; the positions of the test rack and the wall of the integrated test box are adjusted so that the spatial installation position of the electronic equipment to be tested in the integrated test box is the same as the actual installation position; the main PCB board is removed, and a wire burner is installed at the installation position of the main PCB board, so that the flame propagation direction of the wire burner is the same as the actual flame propagation direction on the main PCB board; the electronic equipment to be tested is started; the air flow state in the cabin during the actual operation of the aircraft is simulated; after the electronic equipment to be tested operates normally, the wire burner is remotely ignited; the flame size of the wire burner is adjusted; the combustion condition of the wire burner, the combustion condition of the electronic equipment to be tested, and the flame propagation condition are monitored through a monitoring mechanism; the present invention can more accurately measure the actual flame retardancy performance of the entire electronic equipment.

Description

Technical Field

[0001] The present invention relates to the technical field of aircraft component and system testing, and particularly relates to a method for testing the flame retardancy of airborne electronic equipment for aviation. Background Art

[0002] The fireworthiness airworthiness verification of airborne electronic equipment is an essential link for installing the electronic equipment on an aircraft. Among them, in the current fireworthiness airworthiness verification of airborne electronic equipment, the most important part is the test of the fire prevention performance of the airborne electronic equipment itself.

[0003] Since there are many types of airborne electronic equipment, with great differences in shape, structure and function, it is difficult to have a unified flame retardancy test method suitable for all airborne electronic equipment. When installing airborne electronic equipment, only the fire prevention performance test of the airborne electronic equipment itself can be mainly carried out, and the limitation of the installation area can be assisted to achieve the purpose of airworthiness verification. For example, in the regulations of the Civil Aviation Administration of China (CAAC) on the fireworthiness airworthiness verification of airborne electronic equipment, the airborne electronic equipment must meet the corresponding fire prevention requirements, including that the housing, wires, cables, terminals, connectors, etc. of the equipment must all have fire prevention performance. In the regulations of the Federal Aviation Administration (FAA) of the United States on the fireworthiness airworthiness verification of airborne electronic equipment, it is required that the external housing, internal circuit board, cables and connectors, etc. of the airborne electronic equipment must all have fire prevention performance, be able to withstand a certain high temperature and flame invasion, and will not generate a fire source or cause a fire.

[0004] It is not difficult to find that, whether domestic or foreign, the current fire prevention performance test of airborne electronic equipment is mainly based on the fire prevention or flame retardancy of the various component materials that make up the electronic equipment, that is, through the test of the fire prevention or flame retardancy of the various component materials that make up the airborne electronic equipment, it is theoretically deduced that the electronic equipment assembled from these component materials also has the corresponding fire prevention or flame retardancy when installed on the aircraft.

[0005] The current test method of inferring the fire prevention and flame retardancy of the assembled electronic equipment through the test results of the fire prevention and flame retardancy of components and materials can theoretically obtain the test results representing the fire prevention or flame retardancy of the entire airborne electronic equipment, but there is always a certain gap between this test result and the actual fire prevention or flame retardancy performance of the electronic equipment installed on the aircraft, and there is a certain error range in the test result, which cannot reflect the actual fire prevention or flame retardancy performance of the airborne electronic equipment. Summary of the Invention

[0006] The present invention aims to provide a method for testing the flame retardancy of airborne electronic equipment for aviation, so as to solve the problem that the current test of the flame retardancy of airborne electronic equipment focuses on the test of the various components and materials that make up the electronic equipment, resulting in a certain error between the test result and the actual flame retardancy performance of the airborne electronic equipment.

[0007] To solve the above problems, the present invention adopts the following technical solutions:

[0008] A method for testing the flame retardancy of airborne electronic equipment for aviation uses a testing mechanism to simulate the operating environment of an aircraft cabin and provide a combustion environment for the electronic equipment to be tested, a monitoring mechanism to monitor the combustion changes of the electronic equipment, and an energy mechanism to provide the energy for the normal operation of the electronic equipment; wherein, the testing mechanism is an integrated testing box, including a housing, a test rack arranged in the housing for placing the electronic equipment to be tested, and a wire burner for providing a gradually changing combustion flame to the inside of the electronic equipment to be tested; a plurality of sealing holes are opened on the housing, and the sealing holes are used for the wire connection of the electronic equipment to be tested with the monitoring mechanism and the energy mechanism outside the integrated testing box; an observation window for observation is arranged on the housing; an inflation pipeline for inflating into the housing and an exhaust pipeline for exhausting air from the housing are arranged on the housing; a flowmeter is arranged in the inflation pipeline; the testing method includes the following steps:

[0009] Step 1, open the integrated testing box, and fix the electronic equipment to be tested on the test rack; adjust the positions of the test rack and the box wall of the integrated testing box so that the spatial installation position of the electronic equipment to be tested in the integrated testing box is the same as the actual installation position in the aircraft.

[0010] Step 2, open the housing of the electronic equipment to be tested, remove the main PCB board, and install a wire burner at the installation position of the main PCB board so that the flame spreading direction of the wire burner is the same as the actual flame spreading direction on the main PCB board.

[0011] Step 3, open a notch on one of the device walls of the electronic equipment to be tested for the wire burner to pass through, form a replacement wall, and close the electronic equipment to be tested; start the electronic equipment to be tested; close the integrated testing box, inflate and exhaust air into the integrated testing box, and adjust the air flow state in the integrated testing box through the inflation pipeline and the exhaust pipeline to simulate the air flow state in the cabin during the actual operation of the aircraft.

[0012] Step 4, remotely ignite the wire burner after the electronic equipment to be tested operates normally.

[0013] Step 5, adjust the flame size and flame change of the wire burner according to the preset combustion strategy within the first specified time period; monitor the combustion condition of the wire burner, the combustion condition of the electronic equipment to be tested, the flame spreading condition, and the internal and external temperature values of the electronic equipment to be tested through the monitoring mechanism.

[0014] Step 6, adjust the relative position of the electronic equipment to be tested on the test rack in the integrated testing box to simulate the change of the air pressure environment received by the airborne electronic equipment under the condition of aircraft operation.

[0015] Step 7, within the second specified time period, observe and monitor the combustion situation inside and outside the electronic device under test and the flame spread situation through the observation window, and at the same time monitor the operating state of the electronic device under test through the monitoring mechanism;

[0016] Step 8, draw a temperature graph and a flame spread graph according to the monitoring situation.

[0017] Furthermore, the main PCB board refers to the PCB board with the most electronic components in the electronic device under test, or the PCB board with the most high-power components in the electronic device under test.

[0018] If there is only one PCB board in the entire electronic device under test, then this board is the main PCB board. If there are multiple PCB boards and their power dissipation is the same, then the PCB board with the most electronic components is most likely to catch fire due to component failure or other reasons. Therefore, the PCB board with the most electronic components is designated as the main PCB board; if the number of components on each PCB board is equal, then the PCB board with the most high-power components generates the most heat and is most likely to catch fire due to heat accumulation. Therefore, the PCB board with the most high-power components is designated as the main PCB board. With this setting in this solution, it is possible to simulate and restore the real fire cause as much as possible, test the most unfavorable situation, and thus make the test results more real and accurate.

[0019] In this solution, the installation position of the wire burner is set on the main PCB board where the fire source is likely to be generated. Without affecting their respective operations, it simulates and restores the fire source position and fire source state as realistically as possible, making the test results more accurate and real.

[0020] Furthermore, there are multiple radiation heat plates for simulating the heat dissipation of other electronic devices in the integrated test chamber. Between Step 4 and Step 5, start the radiation heat plates to make the radiation heat plates reach the specified temperature.

[0021] Furthermore, in Step 1, model bodies are also installed on both sides of the installation position of the electronic device under test on the test rack. The model bodies are the same in equipment volume and outer surface material as the equipment near the actual installation position of the electronic device under test on the aircraft; the spatial position relationship between the electronic device under test and the model bodies is the same as the actual spatial position relationship between the electronic device under test and the adjacent equipment on the aircraft; the radiation heat plates are installed on the model bodies.

[0022] By setting up the model body, the spatial environment of the electronic device to be tested when it is actually installed on an aircraft is simulated and restored. At the same time, by setting up the radiation heat plate, the heat dissipation of adjacent electronic devices is simulated, providing a more realistic combustion environment for the test. Installing both the model body and the electronic device to be tested on the test stand not only facilitates installation, but also enables quick replacement by changing the test stand when dealing with different models of electronic devices to be tested and model bodies. It is convenient to operate and has a wide range of applications. In addition, by adjusting the relative positions of the test stand and the integrated test box, the actual spatial positions of the electronic device to be tested, the surrounding adjacent devices, and the cabin during abnormal situations during the operation of the aircraft can be simulated, providing more realistic test scenarios for the test and making the test results more reliable.

[0023] Further, in step three, when closing the housing of the electronic device to be tested, a sealing ring is put on the connecting pipe to block the gap, ensuring that the sealing effect of the replacement wall and the device wall on the electronic device to be tested is the same.

[0024] The diameter of the connecting pipe of the wire burner is 9 - 13 mm. In this solution, 11 mm is preferably selected, and the corresponding gap is a quarter - circular or semi - circular gap with a radius of 8 - 13 mm. Since the housing of the electronic device to be tested is generally composed of 6 device walls, and these device walls are easy to install, mostly rectangular structures except for a small number of special - shaped structures. Whether it is a rectangular structure or a small number of special - shaped structures, for the convenience of installation, there is at least one right - angled contour or a straight - edge contour. For the convenience of processing and sealing, generally a quarter - circular gap is opened on this right - angled contour or a semi - circular gap is opened on the straight - edge contour. Due to the flexibility of the connecting pipe itself, the minimum radius of the gap can be 8 mm, and due to the sealing effect of the sealing ring, the maximum radius of the gap can be 13 mm. Effectively ensuring that without affecting the methane supply and combustion of the wire burner, the sealing effect of the replacement wall on the electronic device to be tested is the same as that of the original device wall, enabling a more realistic and accurate simulation of the flame - retardant situation of the entire electronic device to be tested after an actual fire, and making the test results more accurate.

[0025] Further, the wire burner includes a connecting pipe that is used to communicate with the methane storage gas cylinder through an electronic mass flow controller, and a hollow combustion strip that is connected to the connecting pipe; the combustion strip is in a strip - shaped structure, and a plurality of combustion ports for the flame to emerge are opened on one side of the combustion strip; a remote igniter and an automatic ignition mechanism are provided at the end of the combustion strip; in step four, after the electronic device to be tested operates normally, first methane is introduced into the combustion strip through the connecting pipe, and then the wire burner is ignited by the remote igniter or the automatic ignition mechanism, so that the flame gradually emerges from each combustion port; the internal temperature of the electronic device to be tested is calculated based on the amount of methane flowing out through the combustion ports.

[0026] Further, the monitoring mechanism includes a temperature sensor, a blue LED light, and a high-temperature camera disposed inside the integrated test chamber. The light of the blue LED light covers the entire electronic device under test. During the first specified time period and the second specified time period, the remaining light sources are turned off, and the side of the electronic device under test with openings is observed and monitored through the high-temperature camera only under the illumination of the blue LED light. Different-angle monitoring images are obtained by moving the height of the high-temperature camera and the distance from the opening position of the electronic device under test. Meanwhile, the external temperature of the electronic device under test is monitored through the temperature sensor.

[0027] Further, there are multiple high-temperature cameras, which are respectively installed on the inner wall and the internal moving mechanism of the integrated test chamber to capture the deformation, flame, and smoke spread conditions on each side of the electronic device under test.

[0028] Further, the combustion strategy is as follows: The electronic devices under test are divided into those with fans and those without fans according to whether there is a fan installed inside the electronic device under test. The rate of increase in the flame temperature of those with fans is lower than that of those without fans. Among them, the process of the flame temperature increase for those with fans is:

[0029] Ensure that the flow rate of methane gas generating the flame is 1 L / min.

[0030] The maximum methane flow rate Q peak = (0.071 × h 1.26 - 0.03) × 1.8,

[0031] where Q peak is in standard liters per minute; h is the vertical dimension of the main PCB board in centimeters.

[0032] t decay = 185 × (Q peak -1) / Q peak + 85,

[0033] where t decay is the time when the methane flow rate changes back to 1 standard liter per minute in seconds. peak The automatic ignition sequence is as follows:

[0034] From 0 to 15 seconds, the flow rate is maintained at 1 standard liter per minute.

[0035] From 15 to 85 seconds, the flow rate increases from 1 standard liter per minute to Q

[0036] peak peak ;

[0037] From 85 seconds to t decay peak peakReduce to 1 standard liter per minute;

[0038] At t decay From t to 270 seconds, the flow rate is maintained at 1 standard liter per minute;

[0039] The ignition ends.

[0040] Furthermore, the wire burner is placed at the lowest position of the main PCB board installation location, with a horizontal distance within 9 mm from the adjacent PCB board or the combustible load. The position of the combustion port forms a 45-degree angle with the combustible load, and the distance between adjacent combustion ports is within 5 mm. The coverage area of all combustion ports on one combustion strip accounts for more than 75% of the side area of the combustion strip.

[0041] The combustible load refers to, except for the PCB board, including but not limited to electronic components, installation frames, cables, and other combustible items.

[0042] The principle and advantages of the present invention are as follows:

[0043] Because the simple flammability of materials cannot fully simulate the actual fire risk of airborne electronic equipment, the structure of airborne electronic equipment has a great influence on the combustion result, and during the actual operation process, the heat generation of these equipment, the failure of internal components, the fan designed for heat dissipation will accelerate the oxygen supply during combustion, the pressure of the installation environment, and the heat dissipation of other adjacent equipment and other situations will all affect the actual combustion situation. However, the existing material flame retardant test methods cannot simulate these situations and have serious deficiencies. The present invention effectively solves these problems through ingenious step settings and test scenario construction.

[0044] The present invention belongs to the technical field of aircraft component and system testing. It provides a brand-new test idea for the current inability to conduct flame retardant tests on airborne electronic equipment on an aircraft during power-on operation. It can conduct various extreme tests on the premise of restoring the real flight situation, provides more capabilities for the research and development of airborne electronic equipment, and helps to promote the further development of the aviation equipment industry.

[0045] The present invention maintains the air flow pressure during the test through the inflation channel and the exhaust channel. The radiant heat plate simulates the heat dissipation of other equipment in the real environment, making the integrated test box truly simulate the local space environment of the aircraft cabin; through the setting of the test rack, the spatial position of the electronic equipment to be tested during the test is consistent with the installation position on the actual aircraft, providing a more real combustion environment for the test. And through the setting of the wire burner, replacing the main PCB board to simulate the ignition source, and also making the combustion flame change situation generated by the wire burner more approaching the real flame change situation through the combustion strategy, providing a more real ignition source state for the test and making the test result more accurate and real.

[0046] In addition, this method is convenient to operate, intuitive to observe and monitor, simple to operate as a whole, and the test results are accurate. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 It is a schematic connection diagram of the integrated test box, the monitoring mechanism and the energy mechanism in the first embodiment of the present invention.

[0048] Figure 2 For Figure 1 It is a schematic structural diagram of the integrated test box after removing the observation window.

[0049] Figure 3 It is a schematic installation structure diagram of the burner in the first embodiment of the present invention.

[0050] Figure 4 It is a schematic structural diagram of the burner in the first embodiment of the present invention.

[0051] Figure 5 It is a flowchart of the first embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0052] The following is a further detailed description through specific embodiments:

[0053] The reference numerals in the accompanying drawings of the specification include: integrated test box 1, observation window 11, inflation pipeline 12, air extraction pipeline 13, connecting pipe 141, combustion strip 142, combustion port 143, adjacent PCB boards 144, remote igniter 145, test rack 15, simulation body 151, monitoring mechanism 2, blue LED lamp 21, high-temperature camera 22, energy mechanism 3, electronic device to be tested 4, replacement wall 41, notch 42.

[0054] First Embodiment

[0055] The embodiment is basically as shown in the attached Figure 1 figures: The flame retardancy test method for airborne electronic devices in this embodiment, the flame retardancy test includes combustion characteristics and combustion spread characteristics tests. The test mechanism is used to simulate the operating environment of the aircraft cabin and provide a combustion environment for the electronic device to be tested 4. The monitoring mechanism 2 is used to monitor the combustion change of the electronic device, and the energy mechanism 3 is used to provide energy for the normal operation of the electronic device. As Figure 2As shown in the figure, the test mechanism is an integrated test chamber 1, which includes a housing, a test rack 15 arranged inside the housing for placing the electronic device 4 to be tested, and a wire burner for providing a gradually changing combustion flame inside the electronic device 4 to be tested; a plurality of sealing holes are opened on the housing, and the sealing holes are used for the wire connection between the electronic device 4 to be tested and the monitoring mechanism 2 and the energy mechanism 3 outside the integrated test chamber 1; an observation window 11 for observation is arranged on the housing; an inflation pipeline 12 for inflating into the housing and an air extraction pipeline 13 for extracting air from the housing are arranged on the housing; a flow meter is arranged inside the inflation pipeline 12.

[0056] In this embodiment, the integrated test chamber 1 is a hexahedron structure, including a top plate, a bottom plate, a left side plate, a right side plate, a front plate and a rear plate, and an observation window 11 respectively connected to the top plate, the left side plate, the right side plate and the front plate. Except that the observation window 11 is made of transparent tempered glass, the other six panels are all steel plates. The observation window 11 is arranged obliquely, and the bottom end of the observation window 11 intersects with the top end of the front plate, which is convenient for opening and closing the observation window 11 and for observing the combustion situation inside the integrated test chamber 1 through the observation window 11.

[0057] As Figure 2 shown in the figure, model bodies are also installed on both sides of the installation position of the electronic device 4 to be tested on the test rack 15. The model bodies are the same in equipment volume and external surface material as the equipment near the actual installation position of the electronic device 4 to be tested on the aircraft; the spatial position relationship between the electronic device 4 to be tested and the model bodies is the same as the actual spatial position relationship between the electronic device 4 to be tested and the adjacent equipment on the aircraft. That is, through the setting of the model bodies, the spatial environment around the electronic device to be tested is consistent with the surrounding spatial environment of the electronic device to be tested on the aircraft. A radiation heat plate is installed on the surface of the model body close to the electronic device to be tested, which is used to simulate the heat dissipation situation of adjacent electronic devices, so that the test space where the electronic device to be tested is located truly restores the actual working space, breaking away from the simple study of the flame retardant performance of the material plate itself or the device itself, and starting from the actual working environment, studying the flame retardant performance of the device in a specific environment.

[0058] Through the model bodies, the spatial environment when the electronic device 4 to be tested is actually installed on the aircraft is simulated and restored, providing a more realistic combustion environment for the test. And installing both the model bodies and the electronic device 4 to be tested on the test rack 15 is not only convenient for installation, but also can be quickly replaced by replacing the test rack 15 when dealing with different models of the electronic device 4 to be tested and the model bodies, with convenient operation and wide application range; in addition, by adjusting the relative positions of the test rack 15 and the integrated test chamber 1, the actual spatial positions of the electronic device 4 to be tested and the surrounding adjacent devices and the cabin during the operation of the aircraft when abnormal situations occur can be simulated, providing more realistic test scenarios for the test and making the test results more true and reliable.

[0059] The monitoring mechanism in this embodiment includes a temperature sensor, a blue LED light, and a high-temperature camera 22 disposed in the integrated test box 1. It also includes an intelligent processing device that performs image recognition on the images captured by the high-temperature camera 22. The intelligent processing device in this embodiment is a server computer connected to a display screen. It further includes a spectrum analyzer and a digital oscilloscope for connecting to the output end of the electronic device under test 4, and a signal generator for connecting to the input end of the electronic device under test 4. For the electronic device under test that requires signal input, the signal generator simulates the input signal of the electronic device under test 4 during aircraft operation and sends the corresponding signal to the electronic device under test 4. For the electronic device under test 4 that does not require input signal, the signal generator is not connected.

[0060] The light of the blue LED light covers the entire electronic device under test 4. During the first specified time period and the second specified time period, the rest of the light sources are turned off, and observations and monitoring are carried out only under the illumination of the blue LED light. Mainly monitor the side of the electronic device under test with openings, and obtain monitoring images at different angular positions by moving the height of the high-temperature camera and the distance from the opening position of the electronic device under test. At the same time, monitor the external temperature of the electronic device under test through the temperature sensor.

[0061] There are multiple high-temperature cameras 22 in this embodiment, which are respectively installed on the integrated test box 1 and the internal moving mechanism. The multiple high-temperature cameras 22 installed on the integrated test box 1 are used to capture the deformation, flame, and smoke spread conditions of each side of the electronic device under test 4. The internal moving mechanism is a heat-resistant robotic arm.

[0062] In this embodiment, except for the electronic devices installed in the integrated test box 1, the rest of the devices of the monitoring mechanism 2 are installed in a monitoring box, which facilitates overall installation and maintenance, centralized temperature control, and enables the devices in the monitoring box to be maintained at an ideal working temperature and humidity through conventional means such as fans or cold circulation.

[0063] The energy mechanism 3 in this embodiment uses a generator or a storage power source to form a separate energy mechanism 3 to supply power to the electronic device under test 4, avoiding the influence of surge current generated by the combustion of the electronic device under test 4 or other faults. Compared with directly using mains power supply in general tests, this solution supplies power to the electronic device under test 4 separately, avoiding the influence on the mains network. The energy mechanism 3 in this embodiment has an energy shell for preventing explosion, minimizing the losses caused by the test.

[0064] As Figure 5 shown, when using the above devices to conduct the flame retardancy test on airborne electronic devices for aviation, the test method includes the following steps:

[0065] Step 1: Open the integrated test box 1, and fix the electronic device 4 to be tested on the test rack 15; adjust the positions of the test rack 15 and the wall of the integrated test box 1 so that the spatial installation position of the electronic device 4 to be tested in the integrated test box 1 is the same as the actual installation position on the aircraft.

[0066] Step 2: Open the housing of the electronic device 4 to be tested, remove the main PCB board, and install a wire burner at the installation position of the main PCB board so that the flame spreading direction of the wire burner is the same as the actual flame spreading direction on the main PCB board.

[0067] Step 3: Replace one device wall of the electronic device 4 to be tested with the replacement wall 41 to enclose the electronic device 4 to be tested; start the electronic device 4 to be tested, and for those with power supply and fans, start the fans according to the actual working conditions; close the integrated test box 1, inflate and deflate the integrated test box 1, and adjust the airflow state in the integrated test box 1 through the inflation pipeline 12 and the exhaust pipeline 13 to simulate the airflow state in the cabin during the actual operation of the aircraft.

[0068] Step 4: After the electronic device 4 to be tested operates normally, remotely ignite the wire burner.

[0069] Step 5: Within the first specified time period, adjust the flame size and flame variation of the wire burner according to the preset combustion strategy; monitor the combustion situation of the wire burner, the combustion situation of the electronic device 4 to be tested, the flame spreading situation, and the internal and external temperature changes through the monitoring mechanism. In this article, the flame size only refers to the flame length and energy, and the flame variation refers to the dynamic change situation in the time dimension. When adjusting the wire burner, not only the flame size at a certain time point is adjusted, but also the dynamic change situation of the flame during the entire combustion time period is adjusted. Generally, the flame variation is from small to large and then from large to small gradually, used to simulate the process from the fire getting smaller and then larger to natural extinction after the fire breaks out.

[0070] Step 6: Adjust the relative position of the electronic device 4 to be tested on the test rack 15 in the integrated test box 1 to simulate the change in the air pressure environment received by the airborne electronic device under the condition of aircraft operation.

[0071] Step 7: Within the second specified time period, observe and monitor the combustion situation inside and outside the electronic device 4 to be tested and the flame spreading situation through the observation window 11 and the monitoring mechanism 2, and at the same time monitor the operating state of the electronic device 4 to be tested through the monitoring mechanism 2.

[0072] Step 8: Draw a temperature graph and a flame spreading graph based on the monitoring situation.

[0073] As Figure 3As shown, when installing the line burner, the line burner is brought as close to the main PCB as possible. In step 2, the main PCB is removed, and the line burner is installed on the installation position of the main PCB, which means that the plane where the installed line burner is located is parallel to the plane where the main PCB is located. This solution places the installation position of the line burner as close as possible to the main PCB, which is prone to fire sources, and simulates and restores the fire source position and fire source state as realistically as possible without affecting their respective operations, so that the test results are more accurate and true.

[0074] The main PCB board in this embodiment refers to the PCB board with the most electronic devices in the electronic device 4 under test, or the PCB board with the most high-power devices in the electronic device 4 under test.

[0075] If there is only one PCB board in the entire electronic device 4 to be tested, then this board is the main PCB board. If there are multiple PCB boards and the power and heat dissipation are the same, then the PCB board with the most electronic components is most likely to catch fire due to component failure or other reasons, so the PCB board with the most electronic components is set as the main PCB board; if the number of components on each PCB board is similar, then the PCB board with the most high-power components generates the most heat and is most likely to catch fire due to heat accumulation, so the PCB board with the most high-power components is set as the main PCB board. This scheme is set up in this way, which can simulate and restore the real cause of the fire as much as possible, thereby making the test results more real and accurate.

[0076] like Figure 3 As shown, in step three, the replacement wall 41 is formed by cutting a notch on one of the device walls that originally constitutes the shell of the electronic device 4 to be tested. In this embodiment, a notch 42 for the line burner connecting pipe 141 to pass through is opened on the edge of the replacement wall 41; when the shell of the electronic device 4 to be tested is closed, a sealing ring is put on the connecting pipe 141 to block the notch 42, so as to keep the replacement wall 41 and the device wall consistent in sealing effect on the electronic device 4 to be tested.

[0077] In this embodiment, the diameter of the line burner connecting pipe 141 is 9-13 mm, and 11 mm is preferably selected in this solution. The corresponding notch 42 is a quarter circle or a semi-circular notch 42 with a radius of 8-13 mm. Since the housing of the electronic device 4 to be tested is generally composed of 6 device walls, and these device walls are convenient for installation. Except for a small number of special-shaped structures, most are rectangular structures. Whether it is a rectangular structure or a small number of special-shaped structures, there is at least one right-angle contour or a straight-edge contour for convenient installation. For the convenience of processing and sealing, generally a quarter-circle notch 42 is opened on this right-angle contour or a semi-circular notch 42 is opened on the straight-edge contour. Because of the flexibility of the connecting pipe 141 itself, the minimum radius of the notch 42 can be taken as 8 mm. Because of the sealing effect of the sealing ring, the maximum radius of the notch 42 can be taken as 13 mm. On the premise of effectively ensuring that the methane supply and combustion of the line burner are not affected, the sealing effect of the replacement wall 41 on the electronic device 4 to be tested is the same as that of the original device wall, so that the flame retardant situation of the entire electronic device 4 to be tested after actual ignition can be simulated more truly and accurately, and the test results are more real and accurate.

[0078] In this embodiment, the first specified time and the second specified time are set according to actual needs.

[0079] As Figure 3 and Figure 4 As shown, the line burner includes a connecting pipe 141 used to communicate with a methane storage cylinder through an electronic mass flow controller, and a hollow combustion strip 142 connected to the connecting pipe 141; the combustion strip 142 is in a strip structure, and a plurality of combustion ports 143 for flames to emerge are opened on the top surface of the combustion strip 142; a remote igniter 145 is provided at the end of the combustion strip 142; in step four, after the electronic device 4 to be tested operates normally, first introduce methane into the combustion strip 142 through the connecting pipe 141, and then ignite the line burner through the remote igniter 145 to make the flames gradually emerge from each combustion port 143.

[0080] The combustion strategy in this embodiment is that the electronic device 4 to be tested is divided into a fan-equipped type and a non-fan type according to whether there is a fan installed inside the electronic device 4 to be tested. For the fan-equipped type, the flame temperature rise rate is lower than that of the non-fan type. In this embodiment, the average flame temperature rise rate of the fan-equipped type is half of the flame temperature rise rate of the non-fan type in the corresponding time period.

[0081] In this embodiment, the process of the flame temperature rise of the fan-equipped type is as follows:

[0082] Ensure that the methane gas flow rate for generating the flame is 1 L / min,

[0083] The maximum methane flow rate Q peak = (0.071 × h 1.26- 0.03) × 1.8,

[0084] wherein, Q peak is in the unit of standard liters per minute; h is the vertical dimension of the main PCB board, in the unit of centimeters;

[0085] t decay = 185 × (Q peak - 1) / Q peak + 85,

[0086] wherein, t decay = Q peak is the time when the methane flow rate returns to 1 standard liter per minute after that, in the unit of seconds;

[0087] The automatic ignition sequence is as follows:

[0088] From 0 to 15 seconds, the flow rate is maintained at 1 standard liter per minute;

[0089] From 15 to 85 seconds, the flow rate increases from 1 standard liter per minute to Q peak ;

[0090] From 85 seconds to t decay , the flow rate decreases from Q peak to 1 standard liter per minute;

[0091] From t decay to 270 seconds, the flow rate is maintained at 1 standard liter per minute;

[0092] The ignition ends.

[0093] In this embodiment, the air flow pressure during the test is maintained through the air inlet channel and the air extraction channel, so that the integrated test chamber 1 truly simulates the aircraft cabin environment; through the setting of the test rack 15, the spatial position of the electronic device 4 to be tested during the test is the same as that in the actual aircraft installation, providing a more realistic combustion environment for the test. And through the setting of the wire burner, replacing the main PCB board to simulate the fire source position, and still making the combustion flame gradient generated by the wire burner closer to the real flame change situation through the combustion strategy, all provide a more realistic fire source state for the test, making the test results more accurate and real.

[0094] In addition, this method is easy to operate, intuitive to observe and monitor, and the overall operation is simple, accurate.

[0095] Embodiment 2

[0096] In this embodiment, the linear burner is placed at the lowest position of the main PCB board installation location, with a horizontal distance within 9 mm from the adjacent PCB board 144 or the combustible load. The position of the combustion port forms a 45-degree angle with the combustible load, and the distance between adjacent combustion ports is within 5 mm. The covered area of all the combustion ports on one combustion strip accounts for more than 75% of the area of this side of the combustion strip. By defining the relationship between the covered area of the combustion ports on the combustion strip and the flow channel of the combustion strip, the combustible gas flow space within the combustion strip and the influence of the corresponding combustion ports are defined, and the maximum flame length and flame energy that the combustion strip can simulate as a fire source can be defined. The combustion strip in this embodiment can balance the volume and the range of the fire source that can be simulated, that is, while making the volume of the combustion strip as small as possible, the flame size and flame gradient that the combustion strip can simulate can cover all the discovered fire sources on the aircraft, making the simulation more realistic.

[0097] The combustible load refers to, except for the PCB board, including but not limited to electronic components, mounting frames, cables, and other combustible items.

[0098] Due to the diversity of the electronic devices to be tested, the categories and shapes of their main PCB boards vary greatly. Therefore, it is very difficult to adapt to and replace all the main PCB boards only from the shape and structure of the linear burner itself. Therefore, the present invention does not simulate and restore the main PCB board from the shape, but from the flame combustion situation. At the same time, the present invention overcomes the general fire source simulation method that simply relies on controlling the flow rate of the combustion gas to control the flame combustion situation, but fully considers the space around the fire source, the distance between the fire source and the adjacent PCB board and the nearest combustible load, and at the same time considers the flame spread direction, reducing the test error caused by the inaccurate restoration of the fire source.

[0099] This embodiment can more conveniently simulate and restore the fire occurrence situation inside the device to be tested, making the test more accurate.

[0100] Embodiment Three

[0101] This embodiment fully considers the influence of the change in the air pressure environment during the operation of the aircraft, and dynamically adjusts the pressure inside the integrated test chamber through the inflation pipe and the exhaust pipe. It overcomes the technical prejudice that the airborne equipment currently works in a constant pressure environment, and can simulate the air pressure fluctuation situation in the cabin when the aircraft rapidly ascends or descends when encountering strong air currents. Compared with the generally considered situation that the air pressure regulation system of the aircraft will try its best to maintain the stability of the cabin air pressure, that is, set at the atmospheric pressure equivalent to an altitude of 8000 feet (about 2438 meters), in addition to simulating the normal fluctuation of the atmospheric pressure at an altitude of 8000 feet (the control range of the air pressure regulation system), this embodiment increases the air pressure fluctuation range to more than 2.5 times the normal fluctuation of the atmospheric pressure for hierarchical testing.

[0102] In this embodiment, the influence of the earth's gravity on the operation of the electronic devices in the cabin can be fully considered under normal environments and various extreme environments, making the test results more real and accurate.

[0103] The above are only embodiments of the present invention. Specific technical solutions and / or common knowledge such as characteristics well known in the art are not described in detail herein. It should be noted that for those skilled in the art, without departing from the technical solution of the present invention, several deformations and improvements can still be made, which should also be regarded as the protection scope of the present invention, and these will not affect the implementation effect of the present invention and the practicability of the patent. The protection scope required by this application should be based on the content of its claims, and the specific implementation manners and the like recorded in the specification can be used to interpret the content of the claims.

Claims

1. A method for testing the flame retardancy of airborne electronic equipment for aviation, characterized in that, Rather than theoretically deriving the flame retardancy of airborne electronic equipment through testing the flame retardancy of the materials of each component that makes up the airborne electronic equipment; the flame retardancy testing method uses a testing mechanism to simulate the operating environment of an aircraft cabin and provide a combustion environment for the electronic equipment to be tested, uses a monitoring mechanism to monitor the combustion changes of the electronic equipment, and uses an energy mechanism to provide the energy for the normal operation of the electronic equipment; wherein, the testing mechanism is an integrated testing box, including a housing, a test rack arranged in the housing for placing the electronic equipment to be tested, and a wire burner for providing a gradually changing combustion flame into the interior of the electronic equipment to be tested; a plurality of sealing holes are opened on the housing, and the sealing holes are used for the wire connection between the electronic equipment to be tested and the monitoring mechanism and the energy mechanism outside the integrated testing box; an observation window for observation is arranged on the housing; an inflation pipeline for inflating into the housing and an air extraction pipeline for extracting air from the housing are arranged on the housing; a flowmeter is arranged in the inflation pipeline; the testing method includes the following steps: Step 1, open the integrated testing box, and fix the electronic equipment to be tested on the test rack; adjust the positions of the test rack and the box wall of the integrated testing box so that the spatial installation position of the electronic equipment to be tested in the integrated testing box is the same as the actual aircraft installation position; Step 2, open the housing of the electronic equipment to be tested, remove the main PCB board, install a wire burner at the installation position of the main PCB board, and make the flame spreading direction of the wire burner the same as the actual flame spreading direction on the main PCB board; through the setting of the wire burner, replace the main PCB board to simulate the ignition source; Step 3, open a notch on one of the equipment walls of the electronic equipment to be tested for the wire burner to pass through, form a replacement wall, and close the electronic equipment to be tested; start the electronic equipment to be tested; close the integrated testing box, inflate and extract air into the integrated testing box, and adjust the air flow state in the integrated testing box through the inflation pipeline and the air extraction pipeline to simulate the air flow state in the cabin during the actual aircraft operation; Step 4, after the electronic equipment to be tested operates normally, remotely ignite the wire burner; Step 5, adjust the flame size of the wire burner according to a preset combustion strategy within the first specified time period; monitor the combustion situation of the wire burner, the combustion situation of the electronic equipment to be tested, the flame spreading situation, and the internal and external temperature values of the electronic equipment to be tested through the monitoring mechanism; Step 6, adjust the relative position of the electronic equipment to be tested on the test rack in the integrated testing box to simulate the change in the air pressure environment received by the airborne electronic equipment under the condition of aircraft operation; Step 7, observe and monitor the combustion situation inside and outside the electronic equipment to be tested and the flame spreading situation through the observation window within the second specified time period, and at the same time monitor the operating state of the electronic equipment to be tested through the monitoring mechanism; Step 8, draw a temperature diagram and a flame spreading diagram according to the monitoring situation; The combustion strategy is to divide the electronic equipment to be tested into fan-equipped types and non-fan-equipped types according to whether there is a fan installed inside the electronic equipment to be tested, and the flame temperature increase rate of the fan-equipped type is lower than that of the non-fan-equipped type; among them, the process of the flame temperature increase of the fan-equipped type is: Ensure that the methane gas flow rate for generating flame is 1 L / min. Maximum methane flow rate Q peak = (0.071 × h 1.26 - 0.03) × 1.8, Among them, Q peak is in the unit of standard liters per minute; h is the vertical dimension of the main PCB board, in the unit of centimeter; t decay = 185 × (Q peak -1) / Q peak + 85, where t decay = Q peak is the time for the post-methane flow rate to return to 1 standard liter per minute, in seconds; The automatic ignition sequence is as follows: From 0 to 15 seconds, the flow rate is maintained at 1 standard liter per minute. Between 15 and 85 seconds, the flow rate is increased from 1 standard liter per minute to Q peak ; Between 85 seconds and t decay , the flow rate decreases from Q peak to 1 standard liter per minute; At t decay to 270 seconds, the flow rate is maintained at 1 standard liter per minute; The ignition is completed.

2. The flame retardancy test method for airborne electronic equipment used in aviation according to claim 1, characterized in that, The main PCB board refers to the PCB board with the most electronic components or the PCB board with the most high-power components in the electronic device to be tested.

3. The flame retardancy test method for airborne electronic equipment used in aviation according to claim 1, characterized in that, There are multiple radiant heat plates for simulating the heat dissipation of other electronic devices in the integrated test box. Between Step 4 and Step 5, start the radiant heat plates to make them reach the specified temperature.

4. The flame retardancy test method for airborne electronic equipment used in aviation according to claim 3, wherein In Step 1, model bodies are also installed on both sides of the installation position of the electronic device to be tested on the test rack. The model bodies are the same in equipment volume and external material as the devices near the actual installation position of the electronic device to be tested on the aircraft. The spatial position relationship between the electronic device to be tested and the model bodies is the same as the actual spatial position relationship between the electronic device to be tested and the adjacent devices on the aircraft. The radiant heat plates are installed on the model bodies.

5. The method for testing the flame retardancy of airborne electronic equipment for aviation according to claim 1, characterized in that, In Step 3, when closing the housing of the electronic device to be tested, use a sealing ring to sleeve the connecting pipe to block the gap, and keep the sealing effect of the replacement wall and the device wall on the electronic device to be tested consistent.

6. The method for testing the flame retardancy of airborne electronic equipment for aviation according to claim 5, characterized in that, The wire burner includes a connecting pipe that is used to communicate with the methane storage gas cylinder through an electronic mass flow controller, and a hollow combustion strip that is communicated with the connecting pipe. The combustion strip is in a strip structure, and a plurality of combustion ports for the flame to emerge are opened on one side surface of the combustion strip. A remote igniter and an automatic ignition mechanism are provided at the end of the combustion strip. In Step 4, after the electronic device to be tested operates normally, first introduce methane into the combustion strip through the connecting pipe, and then ignite the wire burner through the remote igniter or the automatic ignition mechanism, so that the flame gradually emerges from each combustion port. The internal temperature of the electronic device to be tested is calculated by the amount of methane flowing out through the combustion ports.

7. The method for testing the flame retardancy of airborne electronic equipment for aviation according to claim 1, characterized in that, The monitoring mechanism includes a temperature sensor, a blue LED light, and a high-temperature camera arranged in the integrated test box. The light of the blue LED light covers the entire electronic device to be tested. In the first specified time period and the second specified time period, turn off the other light sources, and observe and monitor the side of the electronic device to be tested with an opening only under the illumination of the blue LED light, and obtain monitoring images at different angular positions by moving the height of the high-temperature camera and the distance from the opening position of the electronic device to be tested. At the same time, monitor the external temperature of the electronic device to be tested through the temperature sensor.

8. The flame retardancy test method for airborne electronic equipment used in aviation according to claim 7, characterized in that, There are multiple high-temperature cameras, which are respectively installed on the inner wall and the internal moving mechanism of the integrated test box to photograph the deformation, flame, and smoke spread conditions of each side of the electronic device to be tested.

9. The flame retardancy test method for airborne electronic equipment used in aviation according to claim 6, characterized in that The wire burner is placed at the lowest position of the main PCB board installation position, with a horizontal distance within 9 mm from the adjacent PCB board or the combustible load. The position of the combustion port forms a 45-degree angle with the combustible load, the distance between adjacent combustion ports is within 5 mm, and the coverage area of all combustion ports on one combustion strip accounts for more than 75% of the area of this side of the combustion strip.

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