Failure analysis method for transverse acceleration sensor of motor train unit

Abstract

The application discloses a kind of transverse acceleration sensor failure analysis methods for motor train unit, which comprises: testing at room temperature and low temperature, screening to obtain room temperature failure sensor sample and low temperature failure but room temperature not failure sensor sample, disassembling before testing and testing in the process of low temperature failure but room temperature not failure sensor sample, when there is bubble after disassembly, after removing potting glue, low temperature failure but room temperature not failure sensor glue sample is tested again at room temperature, low temperature and low temperature to room temperature respectively;When low temperature failure but room temperature not failure sensor glue sample passes at room temperature, fails at low temperature, but passes after recovery room temperature, open seal processing room temperature failure sensor, when there is bubble, remove potting glue again, and test room temperature failure sensor glue sample, and the failure reason is analyzed.The method can quickly and efficiently find out the deep failure cause of sensor.

Description

Technical Field

[0001] This invention relates to the field of technology, and in particular to a failure analysis method for a lateral acceleration sensor used in high-speed trains. Background Technology

[0002] High-speed trains play a vital role in high-speed, safe, and large-volume transportation, placing high demands on their safety and system integration. Sensors, which transform measured parameters into electrical signals or other desired information outputs according to certain rules, are an indispensable and crucial part of the safety control system of the entire rail transit industry. Furthermore, the integration mechanism of high-speed train systematization and health management platforms, forming a high-speed train systematization product technology platform oriented towards prognostics and health management (PHM), also heavily relies on real-time sensor monitoring.

[0003] Currently, by installing lateral acceleration sensors on the bogies of high-speed trains, real-time monitoring of the trains is conducted to ensure that they operate in normal or optimal condition. However, when the lateral acceleration sensor malfunctions, the train needs to be slowed down or even stopped, significantly impacting operations and affecting future health management planning.

[0004] However, in the current analysis and testing of faulty lateral acceleration sensors, there is no efficient and rapid analytical process for testing faulty sensors. After a fault occurs, it is difficult to accurately find the deep-seated failure mechanism of the sensor, making it difficult for manufacturers to improve their production processes. As a result, high-speed trains frequently experience downtime due to lateral acceleration sensor failures. Summary of the Invention

[0005] Therefore, it is necessary to provide a failure analysis method for lateral acceleration sensors used in high-speed trains to address the technical problem of how to quickly and efficiently analyze and find the causes of lateral acceleration sensor failure.

[0006] A failure analysis method for a lateral acceleration sensor used in high-speed trains, comprising:

[0007] Acquire fault data at the fault site caused by the failure of the lateral acceleration sensor in the EMU.

[0008] Damage detection was performed on the appearance of all lateral acceleration sensors corresponding to the fault data to obtain sensors without external damage;

[0009] Functional tests were performed on each of the sensors without visible damage at room temperature and low temperature to screen out sensor samples that failed at room temperature and sensor samples that failed at low temperature but not at room temperature.

[0010] Functional tests were performed on the sensor sample that failed at low temperature but not at room temperature before disassembly and during disassembly. After disassembly, the presence of air bubbles in the potting compound was observed.

[0011] When there are air bubbles in the potting adhesive of the sensor sample that failed at low temperature but not at room temperature, the potting adhesive of the sensor sample that failed at low temperature but not at room temperature is removed to obtain a de-potted sample of the sensor that failed at low temperature but not at room temperature.

[0012] The adhesive-removed sample of the sensor that failed at low temperature but did not fail at room temperature was tested again at room temperature, low temperature, and low temperature to room temperature.

[0013] When the sensor sample that failed at low temperature but not at room temperature passes the functional test at room temperature, fails the functional test at low temperature but passes the functional test after returning to room temperature, the sensor sample that failed at room temperature is opened for observation.

[0014] When air bubbles are present in the potting compound of the room temperature failure sensor sample, the potting compound is removed to obtain a de-bonded sample of the room temperature failure sensor.

[0015] The degummed sample of the room temperature failure sensor was functionally tested again at room temperature.

[0016] When the de-adhesive sample of the room temperature failed the functional test at room temperature, it was inferred that the presence of air bubbles in the sensor potting adhesive was the cause of the lateral acceleration sensor failure.

[0017] In one embodiment, the step of performing damage detection on the appearance of all lateral acceleration sensors corresponding to the fault data to obtain sensors without external damage includes:

[0018] Clean all lateral acceleration sensors corresponding to the fault data;

[0019] Eliminate all lateral acceleration sensors whose plugs are missing waterproof putty;

[0020] Inspect the other external surfaces of each lateral accelerometer with waterproof putty on the plug;

[0021] When the other exterior surfaces of the lateral acceleration sensor are intact and without cracks, the internal components of the lateral acceleration sensor are treated with potting compound, eliminating the possibility of water ingress causing malfunction, resulting in a sensor without any external damage.

[0022] In one embodiment, the step of performing functional tests on each of the sensors without external damage at room temperature and low temperature, respectively, to screen out sensor samples that fail at room temperature and sensor samples that fail at low temperature but not at room temperature, includes:

[0023] Room temperature test procedure: At room temperature, perform room temperature function test, dynamic acceleration test and vertical vibration interference test on each of the sensors without visible damage, and simultaneously record the output voltage of each sensor without visible damage.

[0024] Low temperature test procedure: At low temperature, perform low temperature test on each of the sensors without visible damage, and simultaneously record the output voltage of each sensor without visible damage.

[0025] Low temperature to room temperature test: After removing each of the sensors without visible damage from the low temperature, let them stand for a preset time. After returning to room temperature, perform room temperature function test, dynamic acceleration test and vertical vibration interference test on each of the sensors without visible damage. Simultaneously record the output voltage of each sensor without visible damage.

[0026] Screening steps: Based on the output voltage, remove the sensors that failed during the room temperature test step, and remove the sensors that failed during the low temperature test step but became effective again during the low temperature to room temperature test step.

[0027] In one embodiment, the step of opening and observing the room temperature failure sensor sample includes:

[0028] The metal casing of the room temperature failure sensor sample was disassembled to expose the potting compound of the room temperature failure sensor sample;

[0029] The surface of the potting compound of the room temperature failure sensor sample is scanned and inspected using a surface groove scanning device to determine whether the surface of the potting compound of the room temperature failure sensor sample is flat and without grooves.

[0030] If so, then there are air bubbles on the surface of the potting compound of the room temperature failure sensor sample;

[0031] If not, X-ray CT scan is performed on the potting compound of the room temperature failure sensor sample to determine whether there are voids inside the potting compound of the room temperature failure sensor sample;

[0032] If so, then there are air bubbles inside the potting compound of the room temperature failure sensor sample.

[0033] In one embodiment, the step of performing functional testing again on the degummed sample of the room temperature failed sensor at room temperature includes:

[0034] At room temperature, the adhesive-removed sample of the room temperature failure sensor was subjected to room temperature function test, dynamic acceleration test and vertical vibration interference test, and the output voltage of each sensor was recorded simultaneously.

[0035] Determine whether the output voltage of the sensor is the same before and after removing the potting compound from the room temperature failed sensor sample;

[0036] If so, the degummed sample of the room temperature failure sensor passes the functional test at room temperature.

[0037] In one embodiment, the step of performing pre-disassembly functional testing and during disassembly functional testing on the low-temperature-failed but room-temperature-not-failed sensor sample when the de-adhesive sample passes the functional test at room temperature, and observing whether there are air bubbles in the potting compound after disassembly, includes:

[0038] Before disassembly, the sensor samples that failed at low temperature but not at room temperature were subjected to room temperature function tests, dynamic acceleration tests, and vertical vibration interference tests, and the output voltage of each sensor was recorded simultaneously.

[0039] During the disassembly process, the sensor samples that failed at low temperature but not at room temperature were subjected to room temperature function tests, dynamic acceleration tests, and vertical vibration interference tests, and the output voltage of each sensor was recorded simultaneously.

[0040] After disassembly, the surface of the potting compound of the sensor sample that failed at low temperature but not at room temperature is scanned and inspected using a surface groove scanning device to determine whether the surface of the potting compound of the sensor sample that failed at low temperature but not at room temperature is flat and without grooves.

[0041] If so, then there are air bubbles on the surface of the potting compound of the sensor sample that failed at low temperature but not at room temperature;

[0042] If not, perform X-ray CT scan on the sensor sample that failed at low temperature but not at room temperature to determine whether there are voids inside the potting compound of the sensor sample that failed at low temperature but not at room temperature.

[0043] If so, then there are air bubbles inside the potting compound of the sensor sample that failed at low temperature but not at room temperature.

[0044] In one embodiment, after the step of inferring that air bubbles in the sensor potting compound are the cause of the lateral acceleration sensor failure when the de-adhesive sample of the sensor that failed at low temperature but not at room temperature passes the functional test at room temperature, fails the functional test at low temperature, but passes the functional test after returning to room temperature, the method further includes:

[0045] The adhesive-removed sample of the room temperature failed sensor was subjected to X-ray fluoroscopic examination to obtain the first X-ray fluoroscopic detection image.

[0046] Inspect and analyze the welding status of each component in the first X-ray imaging image;

[0047] When the desoldering sample of the room temperature failure sensor shows signs of detachment, the detached area is treated with adhesive.

[0048] The desoldering area after adhesive treatment was sliced ​​to obtain the first slice sample;

[0049] The texture of the first desoldering crack at the desoldering location in the first slice sample was observed using a microscope.

[0050] The failure mechanism of the lateral acceleration sensor was obtained by analyzing the texture of the first desoldering crack.

[0051] In one embodiment, the step further includes:

[0052] The adhesive-removed sample of the sensor that failed at low temperature but not at room temperature was subjected to X-ray fluoroscopic examination to obtain a second X-ray fluoroscopic detection image.

[0053] The welding condition of each component in the second X-ray imaging image was examined and analyzed.

[0054] When the desoldering sample of the sensor that failed at low temperature but not at room temperature shows signs of detachment, the detached area is treated with adhesive.

[0055] The desoldering area after adhesive treatment was sliced ​​to obtain a second slice sample.

[0056] The texture of the second weld breakage crack at the weld breakage location in the second slice sample was observed using a microscope.

[0057] By comparing and analyzing the textures of the first and second desoldering cracks, the consistency of the failure mechanism of the lateral acceleration sensor is verified.

[0058] The aforementioned high-speed train uses a failure analysis method for lateral acceleration sensors. Through visual damage inspection, sensors without visible damage are screened for subsequent testing. Functional tests are performed on these sensors at room temperature and low temperature. Sensors that do not fail at both room temperature and low temperature are discarded. Only sensors that fail at room temperature and those that fail at low temperature but not at room temperature are analyzed, thus eliminating irrelevant factors and improving analysis efficiency. Sensors that fail at low temperature but not at room temperature are disassembled, and the potting compound is removed in the presence of air bubbles. Functional tests are then performed at room temperature, low temperature, and a temperature-to-room-temperature transition. If a sensor that fails at low temperature but not at room temperature passes the functional test at room temperature, fails the low-temperature test, but passes the functional test after returning to room temperature, it indicates that... The presence of air bubbles in the potting compound may be a cause of sensor failure, but this is not certain and further verification is needed. Therefore, by opening and observing the room-temperature failed sensor sample, it was determined that air bubbles were present in the potting compound. After removing the potting compound, the sensor was tested again, and the test data before and after removing the potting compound were compared. It was inferred that the presence of air bubbles in the sensor potting compound was the cause of the lateral acceleration sensor failure. This failure was due to the presence of air bubbles in the potting compound, meaning that the potting compound did not completely surround all the components inside the sensor. Low temperatures altered the structure of the potting compound, resulting in different coefficients of thermal expansion. This caused the potting compound to exert forces on the unenclosed components. Over time, this caused the solder joints of the components inside the sensor to break, leading to poor contact and thus causing the sensor to fail at different temperatures. This failure analysis method efficiently and quickly tests faulty sensors. It can rapidly detect and analyze whether sensor failure is caused by air bubbles in the potting compound, enabling manufacturers to promptly identify problems and improve the potting process to enhance sensor quality. It also indirectly avoids frequent shutdowns of high-speed trains due to lateral acceleration sensor failures, thus improving the operational safety and efficiency of high-speed trains. Attached Figure Description

[0059] Figure 1 This is a flowchart illustrating the steps of a failure analysis method for a lateral acceleration sensor used in a high-speed train in one embodiment.

[0060] Figure 2 Here is a seasonal statistics chart of failure occurrences in one embodiment;

[0061] Figure 3 This is a schematic diagram of the appearance damage detection steps in one embodiment;

[0062] Figure 4 This is a schematic diagram comparing voltage signals in one embodiment;

[0063] Figure 5 This is an overview diagram of the output waveform of a dynamic acceleration test in one embodiment;

[0064] Figures 6 to 8 Here are some detailed diagrams of the output waveforms from a dynamic acceleration test in one embodiment;

[0065] Figure 9 and Figure 10 Here is a waveform diagram of the vertical vibration disturbance test output in one embodiment;

[0066] Figure 11 This is an output voltage waveform diagram of a sensor sample that failed at low temperature but not at room temperature, recorded during room temperature function testing before disassembly in one embodiment.

[0067] Figure 12 This is an example of an output voltage waveform recorded during a functional test of a sensor sample that failed at low temperature but not at room temperature during three temperature cycles before disassembly.

[0068] Figure 13 This is an example of an output voltage waveform recorded during a functional test of a sensor sample that failed at low temperature but not at room temperature during three temperature cycles after disassembly, as shown in one embodiment.

[0069] Figure 14 This is a waveform diagram of the output voltage of sensor sample 5 at low temperature in one embodiment;

[0070] Figure 15 and Figure 16 The circuit diagram and voltage waveform diagrams for the diode voltage to ground and the inductor voltage to ground of sensor sample 6 in one embodiment are shown respectively.

[0071] Figure 17 and Figure 18 The images shown are X-ray images of sensor sample 9 and new sensor components, respectively, from one embodiment. Detailed Implementation

[0072] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below. In the description of the present invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention.

[0073] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0074] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0075] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0076] It should be noted that when an element is referred to as being "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. When an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible implementation.

[0077] Please see Figure 1 This invention provides a failure analysis method for a lateral acceleration sensor used in high-speed trains, which includes:

[0078] Step S101: Obtain fault data at the fault site indicating that the EMU malfunction is caused by the failure of the lateral acceleration sensor.

[0079] Specifically, there are various causes of high-speed train malfunctions. Among them, the failure of sensors, which convert measured parameters into electrical signals or other similar information outputs according to certain rules, will also lead to malfunctions in the high-speed train. Data from the fault scene showing malfunctions solely caused by the failure of the lateral acceleration sensor is collected as raw data. Since the failure analysis method of this invention mainly targets the lateral acceleration sensor, which is installed in a high-speed train, it is necessary to combine the data obtained from the high-speed train fault scene and eliminate irrelevant data.

[0080] In one embodiment, the distribution pattern of the fault data across the four seasons is statistically analyzed. If the probability of a fault occurring in winter is greater than in other seasons, it is preliminarily inferred that the lateral acceleration sensor fault is seasonally related. Further, if the probability of a fault occurring in winter is greater than the sum of the probabilities of all other seasons, it is preliminarily inferred that the lateral acceleration sensor fault is seasonally related. Winter refers to December, January, and February. In this embodiment, due to seasonal changes, the main impact on the lateral acceleration sensor is temperature variation. The purpose of this embodiment is to adjust the main focus of the analysis to the impact of temperature changes on the lateral acceleration sensor, while also considering relevant factors of the high-speed train operating environment in the experiments and analyses.

[0081] Specifically, regarding the test case, feedback from Company A indicated a total of 31 68C5 faults (BCU fault codes: 1734 / 1735_1 / 2 bit sensor signal out of range) occurring on CRH380B and CRH380CL EMU trains from January 2018 to January 2020. After review, 7 of the 31 faults were confirmed on-site to be not caused by sensors. Of the remaining 24 faults, 19 occurred during winter (December, January, and February). The statistics are shown in the table below. Figure 2 As shown. To investigate the root cause of the malfunctions, some sensors that reported faults in the current vehicles were returned to the laboratory for testing and analysis. Statistical analysis of the fault data revealed a strong seasonal correlation in the distribution of faults across the four seasons. Therefore, the investigation primarily focused on performing functional tests on the returned sensors at low temperatures, and combined this with relevant experiments and analyses based on the possible operating environments of the current vehicles.

[0082] Step S102: Perform damage detection on the appearance of all lateral acceleration sensors corresponding to the fault data to obtain sensors without external damage.

[0083] Specifically, all lateral acceleration sensors corresponding to the fault data are those in the high-speed train caused by sensor failure. Since the lateral acceleration sensors are installed on the bogies of the high-speed train, they are inevitably subject to collisions under external forces. Generally, a collision will highly likely damage the external appearance of the lateral acceleration sensor, causing internal damage as well. To reduce interference from irrelevant factors in the failure analysis method of this invention, it is necessary to perform external damage inspection on the collected lateral acceleration sensor samples, discarding samples with external damage to ensure more accurate experimental analysis data.

[0084] like Figure 3 As shown, in one embodiment, step S102: the step of performing damage detection on the appearance of all lateral acceleration sensors corresponding to the fault data to obtain sensors without appearance damage includes:

[0085] Step T101: Clean all lateral acceleration sensors corresponding to the fault data.

[0086] Step T102: Remove all lateral acceleration sensors whose plugs are missing waterproof putty.

[0087] Step T103: Inspect the other exterior surfaces of each lateral accelerometer with waterproof putty on the plug.

[0088] Step T104: When the other exterior surfaces of the lateral acceleration sensor are intact and uncracked, the possibility of water ingress causing failure is eliminated because the interior of the lateral acceleration sensor is treated with potting compound, resulting in a sensor without any external damage.

[0089] In step T101, specifically, firstly, all lateral acceleration sensors are clamped and fixed using a mesh grille; then, a high-pressure spray gun is used to fully cover the mesh grille and all lateral acceleration sensors with clean water to remove dust and adhering soil from all lateral acceleration sensors; secondly, a high-pressure spray gun is used to fully cover the mesh grille and all lateral acceleration sensors with cleaning agent to remove oil stains from all lateral acceleration sensors; thirdly, the positions of all lateral acceleration sensors and the mesh grille are adjusted to expose the areas originally covered by the mesh grille; then, a high-pressure spray gun is used to fully cover the mesh grille and all lateral acceleration sensors in the second... The process involves two steps: First, a thorough cleaning with clean water is performed to remove dust and soil from the areas of the lateral accelerometers that were previously covered by the mesh. Next, a high-pressure spray gun is used to completely cover the mesh and all lateral accelerometers with cleaning agent to remove any remaining oil stains. This is followed by a second thorough cleaning with clean water to remove any remaining cleaning agent residue. Finally, warm air (at room temperature) is blown onto the mesh and all lateral accelerometers, gradually loosening the mesh until no moisture remains on the surface of any of the lateral accelerometers. This completes the cleaning process for all lateral accelerometers corresponding to the fault data.

[0090] Using the above cleaning method, special cleaning agents are used to remove oil stains. For example, for the yellow grease that often adheres to sensors, thinner or gasoline can be used for cleaning. This can thoroughly and quickly clean the stains on the sensor surface, exposing the sensor's appearance as much as possible, which facilitates efficient inspection of the appearance for subsequent steps.

[0091] In step T102, specifically, the waterproof sealant on the plug of the lateral acceleration sensor is a crucial waterproof component that prevents external moisture from entering the sensor during use. If this component is missing, water is highly likely to enter the sensor, leading to a short circuit and directly indicating the cause of sensor failure. Therefore, to further analyze other possible causes of sensor failure, sensors missing waterproof sealant need to be discarded, and only sensors with intact sealant should be retained for subsequent testing and analysis to ensure the reliability of the experiment.

[0092] In step T103, specifically, the appearance of other surfaces of each lateral accelerometer with waterproof putty on the plug can be inspected by comparing and analyzing the appearance of sensors of the same model. In one embodiment, the appearance of the sensor to be inspected is scanned to obtain appearance comparison data. This comparison data is compared with the appearance data of sensors of the same model. When the difference between the two is within a reasonable threshold, it can be determined that the corresponding sensor has no appearance damage; otherwise, the corresponding sensor has appearance damage. The scanner can be an object appearance contour scanner or an appearance surface scanner. Furthermore, to accurately determine the appearance damage, a second scan comparison can be performed to increase the reliability of the appearance data comparison results.

[0093] In step T104, specifically, the interior of the lateral acceleration sensor is potted with glue, and the components inside the sensor are covered by the glue. The outer surface of the glue is then wrapped with a metal box, forming a secondary waterproof protection for the internal components of the sensor. Therefore, when the other exterior surfaces of the lateral acceleration sensor are intact and uncracked, the possibility of water ingress causing failure is eliminated. At this time, a sensor without external damage can be obtained.

[0094] Understandably, using the aforementioned method of detecting external damage allows for accurate determination of whether a sensor sample's failure is due to an internal short circuit caused by a waterproofing issue. If the sensor's failure is indeed due to a waterproofing problem, that sample can be excluded, facilitating a more in-depth analysis of the sensor's failure cause. Simultaneously, inspection of the sensor plug and other external surfaces revealed no signs of water ingress. Furthermore, the internal housing of the sensor contains sealing adhesive, which preliminarily rules out the possibility of water ingress, reducing the need for waterproofing performance testing and improving the efficiency of failure analysis.

[0095] Step S103: Perform functional tests on each of the sensors without visible damage at room temperature and low temperature respectively, and screen out the sensor samples that fail at room temperature and sensor samples that fail at low temperature but do not fail at room temperature.

[0096] Specifically, there is a set of testing standards for whether a lateral acceleration sensor is faulty, mainly judged by the sensor's output voltage and sensitivity. The most direct way to determine if the sensor is damaged or malfunctioning is by directly measuring the output voltage. Nine test samples were investigated, as mentioned in step S101: one unused new sensor and eight sensors reported as faulty in existing vehicles. Fault verification tests were conducted on samples 1-8 at Company A. Root cause investigations were carried out on samples that reproduced the fault at Company A, which were then sent to Company B. Simultaneously, Company A conducted a root cause investigation on sample 9, which was also an unused new sensor.

[0097] According to the on-site fault investigation report provided by Company A, the on-site faults and in-warehouse inspection results of samples 2-8 (a total of 7 samples) were reviewed. Of the 7 on-site vehicle faults: 4 were resolved within 30 minutes after the 1734 / 1735 fault was reported. In-warehouse inspection: In 3 cases, the sensor voltage signal was outside the 1734 / 1735 fault setting condition range; in another case, the first measurement showed a sensor voltage signal of 0.24V, within the 1734 / 1735 fault setting condition range, and the signal returned to normal at 4.96V on the second measurement. 2 cases did not resolve after the 1734 / 1735 fault was reported. In-warehouse inspection: In these two cases, the sensor voltage signals were 0.13V and 2.49V respectively, within the 1734 / 1735 fault setting condition range. In the remaining fault, the 1734 / 1735 fault was reported 3 times in one day. In-warehouse inspection: Sensor voltage signal is 4.98V, which is outside the fault setting condition range of 1734 / 1735. See Table 1 below:

[0098]

[0099] Table 1

[0100] Based on the above data analysis and on-site investigation results, relevant tests were conducted on 8 samples. Before the tests began, each sample underwent a visual inspection. Seven samples returned from the field were found to be somewhat dirty, with waterproof sealant on the plugs, but no other abnormalities were found. The tests were conducted and recorded according to the test outline, following the sequence of room temperature functional testing, low temperature testing, dynamic acceleration testing, and vertical vibration interference testing. Before the tests, the sensor plugs and other external surfaces of the sensor were inspected; no signs of water ingress were found, and the internal housing of the sensor contained sealant. The possibility of water ingress was preliminarily ruled out, therefore a waterproof performance test was not conducted.

[0101] In one embodiment, step S103: the step of performing functional tests on each of the sensors without external damage at room temperature and low temperature respectively, and screening out sensor samples that fail at room temperature and sensor samples that fail at low temperature but not at room temperature, includes:

[0102] Room temperature test procedure: At room temperature, perform room temperature function test, dynamic acceleration test and vertical vibration interference test on each of the sensors without visible damage, and simultaneously record the output voltage of each sensor without visible damage.

[0103] Low temperature test procedure: At low temperature, perform low temperature test on each of the sensors without visible damage, and simultaneously record the output voltage of each sensor without visible damage.

[0104] Low temperature to room temperature test: After removing each of the sensors without visible damage from the low temperature, let them stand for a preset time. After returning to room temperature, perform room temperature function test, dynamic acceleration test and vertical vibration interference test on each of the sensors without visible damage. Simultaneously record the output voltage of each sensor without visible damage.

[0105] Screening steps: Based on the output voltage, remove the sensors that failed during the room temperature test step, and remove the sensors that failed during the low temperature test step but became effective again during the low temperature to room temperature test step.

[0106] The test parameters, conditions, and evaluation methods for the room temperature test are shown in Table 2 below:

[0107]

[0108] Table 2

[0109] Functional tests at room temperature were conducted on both the ESRA test bench and a manual test bench. Sample #8 failed the test. Specific test values ​​are shown in Table 3.

[0110]

[0111] Table 3

[0112] In the low-temperature test and the low-temperature to room temperature test, the low-temperature test was conducted in a temperature chamber. Since sample 8 failed the room temperature functional test, no further tests were performed. The test parameters, conditions, and evaluation methods are shown in Table 4 below.

[0113]

[0114] Reference standard: DIN EN 60068-2-1AB:2008

[0115] Table 4

[0116] The low-temperature test was conducted in a temperature chamber. Since sample 8 failed the functional test at room temperature, no further testing was performed. The low-temperature test was conducted at -40℃, with functional tests performed at 25℃ before and after the initial test. Specific test values ​​are shown in Table 5.

[0117]

[0118] Table 5

[0119] like Figure 4As shown, by comparing the voltage signals of samples 5 and 6 at -40℃ and 25℃, all 7 samples passed the test at 25℃ before the low-temperature test; samples 5 and 6 failed the test at -40℃ during the low-temperature test; and samples 5 and 6 recovered at 25℃ after the low-temperature test, and all 7 samples passed the test.

[0120] The dynamic acceleration tests in the above embodiments are conducted on a vibration test bench, which is a simulator or simulation platform that simulates the operation of a high-speed train. It typically consists of a motor and a mounting platform. The motor's rotation simulates the operation of a high-speed train, while the mounting platform simulates the bogie. This structure can be obtained from existing technologies and will not be described in detail here. The test setup for the dynamic acceleration test is shown in Table 6.

[0121]

[0122] Table 6

[0123] In the dynamic acceleration test, the experiment was conducted at peak accelerations of ±1g, ±1.5g, and ±2g. All sensor signal outputs were normal, without interruption or abnormal fluctuations. Comparison confirmed that there was no significant difference between the new (sample 1) and old (samples 2-7) sensor signals, and the output voltages of all sensors at peak values ​​were within tolerance ranges. The test passed. The test output waveforms are shown below. Figure 5 , Figure 6 , Figure 7 as well as Figure 8 ,in, Figure 5 Overview of Acceleration (5Hz~30Hz) at ±1g acceleration (5Hz~30Hz) Figure 6 Detailed Figure for ±1g Acceleration (10Hz) Figure 7 Detailed Figure (10Hz) at ±1.5g acceleration. Figure 8 The image shows a detailed view (10Hz) at ±2g acceleration. It should be noted that due to differences in sensor accuracy and sensitivity, there are some differences between the test sample and the 500g reference sensor.

[0124] The vertical vibration interference tests in the above embodiments are conducted on a vibration test bench, which is a simulator simulating the operation of a high-speed train. Alternatively, it can be called a simulation platform, generally consisting of a motor and a mounting platform. The motor's rotation simulates the operation of a high-speed train, while the mounting platform simulates the bogie. This structure can be obtained from existing technologies and will not be described in detail here. The test setup for the vertical vibration interference test is shown in Table 7.

[0125]

[0126] Table 7

[0127] In the vertical vibration interference test, the test fixture was rotated 90° on the vibration test bench, and the 500G reference sensor was adjusted to the working direction. Inspection confirmed that the signal output of the test sample was normal in the non-working direction, and all tested sensors output 0g. There were no interruptions or abnormal fluctuations in the output signal, and no other abnormalities were found during the test. The test output waveform is shown below. Figure 9 and Figure 10 ,in, Figure 9 For an overview, Figure 10 These are detailed images.

[0128] After testing, 4 out of the 7 lateral acceleration sensors that reported faults 1734 / 1735 in the field passed the test, while 3 failed. Among the failed samples, sensor #8 failed at room temperature, while sensors #5 and #6 failed at low temperature. The results of the test process are summarized in Table 8.

[0129]

[0130] Table 8

[0131] Therefore, through the above embodiments, the sensor samples that failed at room temperature and the sensor samples that failed at low temperature but not at room temperature were screened out, which are the 4 samples that passed the test. These 4 samples that passed the test will continue to undergo subsequent failure cause analysis tests.

[0132] Step S104: Perform functional tests on the sensor sample that failed at low temperature but not at room temperature before disassembly and during disassembly. After disassembly, observe whether there are air bubbles in the potting compound.

[0133] Specifically, this step requires functional testing before disassembly and during disassembly. This is because the sample is a sensor that failed at low temperatures but not at room temperature, while the disassembly process is conducted at room temperature, meaning the sample is in a "normal" state at room temperature. Although the correctness of the disassembly method could be verified by disassembling two new sensor samples using the same method, to make the experiment more rigorous and the data more accurate, real-time observation of the sensor sample's output voltage before and during disassembly greatly improves the reliability of the experiment.

[0134] In one embodiment, step S104: performing functional tests on the sensor sample that failed at low temperature but not at room temperature before disassembly and during disassembly, and observing whether there are air bubbles in the potting compound after disassembly, includes:

[0135] Before disassembly, the sensor samples that failed at low temperature but not at room temperature were subjected to room temperature function tests, dynamic acceleration tests, and vertical vibration interference tests, and the output voltage of each sensor was recorded simultaneously.

[0136] During the disassembly process, the sensor samples that failed at low temperature but not at room temperature were subjected to room temperature function tests, dynamic acceleration tests, and vertical vibration interference tests, and the output voltage of each sensor was recorded simultaneously.

[0137] After disassembly, the surface of the potting compound of the sensor sample that failed at low temperature but not at room temperature is scanned and inspected using a surface groove scanning device to determine whether the surface of the potting compound of the sensor sample that failed at low temperature but not at room temperature is flat and without grooves.

[0138] If so, then there are air bubbles on the surface of the potting compound of the sensor sample that failed at low temperature but not at room temperature;

[0139] If not, perform X-ray CT scan on the sensor sample that failed at low temperature but not at room temperature to determine whether there are voids inside the potting compound of the sensor sample that failed at low temperature but not at room temperature.

[0140] If so, then there are air bubbles inside the potting compound of the sensor sample that failed at low temperature but not at room temperature.

[0141] Thus, by disassembling the metal casing of a sensor sample that failed at low temperatures but not at room temperature, the potting compound of the sensor sample that failed at low temperatures but not at room temperature is exposed. This allows a surface groove scanning device to quickly scan and inspect the surface of the potting compound of the sensor sample that failed at low temperatures but not at room temperature. By comparing the data with the surface of a sensor with normal potting compound and no air bubbles, the surface groove scanning device can determine whether the surface of the potting compound of the sensor sample that failed at low temperatures but not at room temperature is smooth and without grooves. It is understandable that when the conclusion drawn from the comparison is that the surface of the potting compound of the sensor sample that failed at low temperatures but not at room temperature is smooth and without grooves, it only indicates that the potting compound is smooth on the outside, not that there are no grooves inside the potting compound. In this case, it is necessary to use X-ray CT for 3D stereoscopic scanning to further confirm the presence of air bubbles inside the potting compound. Thus, since surface groove scanning equipment has a fast scanning speed, while X-ray CT scanning is relatively time-consuming, and due to the effects of air pressure and the different densities of the medium, air bubbles inside the potting compound have a high probability of moving to the surface of the potting compound during the pouring process. After cooling, the potting compound often forms a space between itself and the metal shell, resulting in grooves on the surface of the potting compound after the metal shell of the sensor is removed. Therefore, by first performing surface scanning with surface groove scanning equipment, in most failure analysis cases, sensor samples that have low-temperature failures but have not failed at room temperature due to the presence of air bubbles can be quickly screened out.

[0142] Step S105: When there are air bubbles in the potting adhesive of the sensor sample that failed at low temperature but not at room temperature, remove the potting adhesive from the sensor sample that failed at low temperature but not at room temperature to obtain a de-adhesive sample of the sensor that failed at low temperature but not at room temperature.

[0143] Specifically, when air bubbles are present in the potting compound of a sensor sample that fails at low temperatures but not at room temperature, based on the characteristics of thermal expansion and contraction and temperature stress, it can be preliminarily inferred that the presence of air bubbles in the potting compound may cause uneven stress changes within the potting compound during long-term use due to temperature variations. This could lead to open circuits in some components under temperature stress, ultimately causing the entire sensor to fail. Therefore, to verify this, it is necessary to remove the potting compound adhering to and surrounding the components before conducting subsequent tests.

[0144] Step S106: Perform functional tests again on the de-adhesive sample of the sensor that failed at low temperature but did not fail at room temperature at room temperature, low temperature, and low temperature to room temperature.

[0145] Specifically, for sensor samples that fail at low temperatures but not at room temperature, after removing the internal potting compound, functional testing is required to verify the impact of air bubbles in the potting compound on sensor failure. By comparing the data before and after removing the potting compound, it can be determined whether the presence of air bubbles in the potting compound affects sensor failure.

[0146] Step S107: When the sensor sample that failed at low temperature but not at room temperature passes the functional test at room temperature, fails the functional test at low temperature but passes the functional test after returning to room temperature, the sensor sample that failed at room temperature is opened for observation.

[0147] Specifically, the "opening and observation" process refers to disassembling the metal casing of the sensor to observe the encapsulation inside. During the sensor manufacturing process, liquid potting compound is poured into the metal casing, or a mold is used to pour the potting compound. After the liquid potting compound cools, it encapsulates the sensor element as a whole. In this embodiment, the "opening and observation" process involves removing the metal casing of the sensor to observe the encapsulation of the element by the potting compound.

[0148] In one embodiment, the step of opening and observing the room temperature failure sensor sample includes:

[0149] The metal casing of the room temperature failure sensor sample was disassembled to expose the potting compound of the room temperature failure sensor sample;

[0150] The surface of the potting compound of the room temperature failure sensor sample is scanned and inspected using a surface groove scanning device to determine whether the surface of the potting compound of the room temperature failure sensor sample is flat and without grooves.

[0151] If so, then there are air bubbles on the surface of the potting compound of the room temperature failure sensor sample;

[0152] If not, X-ray CT scan is performed on the potting compound of the room temperature failure sensor sample to determine whether there are voids inside the potting compound of the room temperature failure sensor sample;

[0153] If so, then there are air bubbles inside the potting compound of the room temperature failure sensor sample;

[0154] If not, then there are no air bubbles inside the potting compound of the room temperature failure sensor sample, and the potting compound has strong encapsulation with the component. In this case, it can be ruled out that the presence of air bubbles in the potting compound caused the component to be subjected to external force, resulting in pin breakage and failure.

[0155] Thus, by disassembling the metal casing of the room temperature failure sensor sample, the potting compound is exposed, allowing a surface groove scanning device to quickly scan and inspect the surface of the potting compound. By comparing the data with the surface of a sensor with properly poured potting compound and no air bubbles, the device can determine whether the surface of the potting compound in the room temperature failure sensor sample is smooth and free of grooves. It is understandable that if the conclusion is that the surface of the potting compound in the room temperature failure sensor sample is smooth and free of grooves, this only indicates that the potting compound is smooth on the outside, not that there are no grooves inside. In this case, X-ray CT 3D scanning is needed to further confirm the presence of air bubbles inside the potting compound. Thus, since surface groove scanning equipment has a fast scanning speed, while X-ray CT scanning is relatively time-consuming, and due to the effects of air pressure and the different densities of the medium, air bubbles inside the potting compound have a high probability of moving to the surface of the potting compound during the pouring process. After cooling, the potting compound often forms a space between itself and the metal shell, resulting in grooves on the surface of the potting compound after the metal shell of the sensor is removed. Therefore, using surface groove scanning equipment to perform surface scanning can quickly screen out room temperature failure sensor samples containing air bubbles in most failure analysis cases.

[0156] Step S108: When there are air bubbles in the potting adhesive of the room temperature failure sensor sample, remove the potting adhesive from the room temperature failure sensor sample to obtain a de-adhesive sample of the room temperature failure sensor.

[0157] Specifically, when air bubbles are present in the potting compound of a sensor sample that failed at room temperature, based on the characteristics of thermal expansion and contraction and temperature stress, it can be preliminarily inferred that the presence of air bubbles in the potting compound may cause uneven stress changes within the potting compound during long-term use due to temperature variations. This could lead to open circuits in some components under temperature stress, ultimately causing the entire sensor to fail. Therefore, to verify this, it is necessary to remove the potting compound adhering to and surrounding the components before conducting subsequent tests.

[0158] Since the potting compound is applied to the sensor element by pouring, removing the potting compound may damage the element. Therefore, to verify the feasibility of the disassembly method, in one embodiment, when air bubbles are present in the potting compound of the room-temperature failed sensor sample, the same method is used to disassemble the potting compound of two new sensor samples. The two sensors after removing the potting compound are then powered on and tested. When both new sensors function normally at 25°C (room temperature), the same disassembly method is used to remove the potting compound from the room-temperature failed sensor sample, resulting in a room-temperature failed sensor sample without the potting compound. This avoids the accuracy of the test data being affected by incorrect disassembly methods. This disassembly verification method can also be used to disassemble sensor samples that fail at low temperatures but not at room temperature; the steps and principles are the same and will not be repeated here.

[0159] Step S109: Perform a functional test again on the degummed sample of the room temperature failure sensor at room temperature.

[0160] Specifically, after removing the internal potting compound from the room temperature failure sensor sample, functional testing is required to verify the impact of the potting compound containing air bubbles on the sensor failure. By comparing the data before and after removing the potting compound, it can be determined whether the presence of air bubbles in the potting compound affects the sensor failure.

[0161] In one embodiment, step S109: the step of performing functional testing again on the degummed sample of the room temperature failure sensor at room temperature includes:

[0162] At room temperature, the adhesive-removed sample of the room temperature failure sensor was subjected to room temperature function test, dynamic acceleration test and vertical vibration interference test, and the output voltage of each sensor was recorded simultaneously.

[0163] Determine whether the output voltage of the sensor is the same before and after removing the potting compound from the room temperature failed sensor sample;

[0164] If so, the degummed sample of the room temperature failure sensor passes the functional test at room temperature.

[0165] Thus, by comparing the output voltage data before and after removing the potting compound, we can preliminarily determine the cause of sensor failure due to the presence of air bubbles in the potting compound. In other words, the sensor sample that failed at room temperature passed the functional test at room temperature after removing the potting compound. This means that the sensor that originally failed at room temperature under the potting compound containing air bubbles recovered its normal output voltage after removing the potting compound, and all functional tests were normal. It can be inferred that the potting compound containing air bubbles damaged the sensor components.

[0166] Step S110: When the debonded sample of the room temperature failed the functional test at room temperature, it is inferred that the presence of air bubbles in the sensor potting adhesive is the cause of the lateral acceleration sensor failure.

[0167] Specifically, after steps S101 to S109, for sensor samples that failed at low temperatures but not at room temperature, the functional test passed at room temperature, but failed at low temperatures. However, after returning to room temperature, the functional test still failed. However, for sensor samples that failed at room temperature, the sensor that originally failed under the potting compound containing air bubbles recovered its normal output voltage and all functional tests were normal after the potting compound was removed. It can be inferred that the potting compound containing air bubbles damaged the sensor components. In other words, the presence of air bubbles in the sensor potting compound is the cause of the failure of the lateral acceleration sensor.

[0168] The aforementioned high-speed train uses a failure analysis method for lateral acceleration sensors. Through visual damage inspection, sensors without visible damage are screened for subsequent testing. Functional tests are performed on these sensors at room temperature and low temperature. Sensors that do not fail at both room temperature and low temperature are discarded. Only sensors that fail at room temperature and those that fail at low temperature but not at room temperature are analyzed, thus eliminating irrelevant factors and improving analysis efficiency. Sensors that fail at low temperature but not at room temperature are disassembled, and the potting compound is removed in the presence of air bubbles. Functional tests are then performed at room temperature, low temperature, and a temperature-to-room-temperature transition. If a sensor that fails at low temperature but not at room temperature passes the functional test at room temperature, fails the low-temperature test, but passes the functional test after returning to room temperature, it indicates that... The presence of air bubbles in the potting compound may be a cause of sensor failure, but this is not certain and further verification is needed. Therefore, by opening and observing the room-temperature failed sensor sample, it was determined that air bubbles were present in the potting compound. After removing the potting compound, the sensor was tested again, and the test data before and after removing the potting compound were compared. It was inferred that the presence of air bubbles in the sensor potting compound was the cause of the lateral acceleration sensor failure. This failure was due to the presence of air bubbles in the potting compound, meaning that the potting compound did not completely surround all the components inside the sensor. Low temperatures altered the structure of the potting compound, resulting in different coefficients of thermal expansion. This caused the potting compound to exert forces on the unenclosed components. Over time, this caused the solder joints of the components inside the sensor to break, leading to poor contact and thus causing the sensor to fail at different temperatures. This failure analysis method efficiently and quickly tests faulty sensors. It can rapidly detect and analyze whether sensor failure is caused by air bubbles in the potting compound, enabling manufacturers to promptly identify problems and improve the potting process to enhance sensor quality. It also indirectly avoids frequent shutdowns of high-speed trains due to lateral acceleration sensor failures, thus improving the operational safety and efficiency of high-speed trains.

[0169] In one embodiment, after step S110, that is, after the step of inferring that the presence of air bubbles in the sensor potting compound is the cause of the lateral acceleration sensor failure when the room temperature failure sensor debonded sample passes the functional test at room temperature, the method further includes:

[0170] The adhesive-removed sample of the room temperature failed sensor was subjected to X-ray fluoroscopic examination to obtain the first X-ray fluoroscopic detection image.

[0171] Inspect and analyze the welding status of each component in the first X-ray imaging image;

[0172] When the desoldering sample of the room temperature failure sensor shows signs of detachment, the detached area is treated with adhesive.

[0173] The desoldering area after adhesive treatment was sliced ​​to obtain the first slice sample;

[0174] The texture of the first desoldering crack at the desoldering location in the first slice sample was observed using a microscope.

[0175] The failure mechanism of the lateral acceleration sensor was obtained by analyzing the texture of the first desoldering crack.

[0176] In one embodiment, the step further includes:

[0177] The adhesive-removed sample of the sensor that failed at low temperature but not at room temperature was subjected to X-ray fluoroscopic examination to obtain a second X-ray fluoroscopic detection image.

[0178] The welding condition of each component in the second X-ray imaging image was examined and analyzed.

[0179] When the desoldering sample of the sensor that failed at low temperature but not at room temperature shows signs of detachment, the detached area is treated with adhesive.

[0180] The desoldering area after adhesive treatment was sliced ​​to obtain a second slice sample.

[0181] The texture of the second weld breakage crack at the weld breakage location in the second slice sample was observed using a microscope.

[0182] By comparing and analyzing the textures of the first and second desoldering cracks, the consistency of the failure mechanism of the lateral acceleration sensor is verified.

[0183] Thus, by using X-ray imaging and crack texture analysis, the correctness of the analysis process for the causes of sensor failure in the above embodiments can be further verified. At the same time, the failure time of the sensor, i.e. the service life of the sensor, can also be inferred based on the morphology of the crack texture and the fault statistics.

[0184] Following the guidance of the above embodiments, in this specific embodiment, we continue with the practical operation of failure cause analysis testing on the four samples that passed the initial test, and detail the failure cause investigation process. An overview of the investigation steps and items is shown in Table 9:

[0185]

[0186] Table 9

[0187] Functional tests were conducted on samples 5 and 6 at room temperature before disassembly. Before opening the sensors, both sensors were placed in a temperature chamber set to a range of 80°C to -40°C. The test process was recorded as follows: Figure 11 As shown in the figure, the area marked by the wireframe on the left represents the signal changes when the sensor is disconnected to measure current and resistance. The output signal changes as the temperature drops from 80℃ to -40℃. When sample 5 is disconnected and then connected, the output voltage first rises and then falls.

[0188] Specific test data are shown in Table 10:

[0189]

[0190] Table 10

[0191] After one day of rest, a second test was conducted, for a total of three temperature cycles. At high temperatures, both sensors functioned normally; at low temperatures, neither sensor output a signal. The current value for sample 5 was 11.05 mA, and the current value for sample 6 was 7.66 mA. Figure 12 As shown.

[0192] Samples 5 and 6 were disassembled and measured. After measurement, the sensors were opened and the metal protective shell and its surface adhesive were removed. Upon inspection after opening the shell, air bubbles were found in the adhesive on the back of the two sensor circuit boards.

[0193] After disassembly, the sensor was placed back into the temperature chamber for testing and analysis, such as... Figure 13 As shown. However, due to the sensor's special structure, opening the cover for disassembly may have some impact on the sensor, and some components may be damaged during the disassembly process.

[0194] The main findings during the testing process are as follows:

[0195] 1. After removing the outer casing, measurements revealed that the input resistance values ​​of both sensors were at their maximum values.

[0196] 2. After removing the inner metal shell, the current value of sample 5 was as high as before the lid was opened; the resistance value of sample 6 became extremely high, but the current value was normal.

[0197] 3. Sample 5 works normally at room temperature and high temperature, but the signal output is 0V at low temperature.

[0198] 4. Sample 6 can work up to the second cycle during the test, but it often fails at low temperatures.

[0199] The final measurement results are shown in Table 11:

[0200]

[0201] Table 11

[0202] To further analyze the cause of the failure, the adhesive near the sensor components was removed, and air bubbles were clearly visible on the back of both sensor boards. Based on the test results above, the adhesive was selectively removed from the corresponding test points of both sensors for further testing. The tests were conducted in a temperature chamber set to 80℃ to -40℃.

[0203] like Figure 14 As shown, sample 5 exhibits an output voltage that fluctuates between 5V (normal) and 2.5V (fault) at low temperatures. Based on the test results, it is inferred that the failure of sensor sample 5 is due to an open circuit in a resistor at low temperatures. Furthermore, the sensor output is abnormal (no signal and extremely high impedance). The air bubbles in the adhesive on the sensor circuit board are likely the root cause of the component failure.

[0204] like Figure 15 and Figure 16 As shown, Figure 15 The voltage of diode 202 to ground in sensor sample 6 is shown. Figure 15 The portion circled in the middle) and the voltage of inductor D200 to ground ( Figure 15 (Part 2 in the middle circle) During testing of sensor sample 6, it was found that the signal at the front end of inductor L200 functioned normally at both high and low temperatures, with a front-end resistance of 7.2 KOhm. Comparing this to the previously measured maximum resistance of the sensor confirmed that the inductor's front-end resistance was normal. Further testing revealed that the signal in the sample 6 circuit was normally cut off at the front end of inductor 200, therefore, it was deduced that the sensor failure was caused by an open circuit in inductor 200. The air bubbles in the adhesive on the sensor circuit board were likely the root cause of the component failure.

[0205] Sample 8 underwent an open-cover inspection. The sensor was opened and the internal metal protective shell was removed. Upon opening, an air bubble was found in the adhesive on the back of the sensor circuit board; some capacitors and resistors lacked potting compound coverage; and some resistors had incomplete potting compound coverage. The sensor was retested at room temperature, and the test results are shown in Table 12.

[0206]

[0207] Table 12

[0208] As shown in Table 12 above, the sensor returned to normal function at room temperature after the cover was opened and the internal metal casing removed. Based on the disassembly and inspection results, it was deduced that the root cause of the fault was related to air bubbles in the adhesive on the sensor board. Through circuit analysis, it was speculated that the fault was caused by an open circuit in some resistors.

[0209] Sample 9 was disassembled and its malfunction analyzed. Before opening sensor sample 9, it was placed in a temperature chamber for testing, with the temperature range set from 25℃ to -40℃. The sample functioned normally at 25℃, but the output signal changed twice when the temperature dropped to 0℃ and -40℃. The sensor function returned to normal when the temperature was raised back to 25℃. Specific values ​​are shown in Table 13.

[0210]

[0211] Table 13

[0212] The sensor was opened and the internal metal protective shell was removed. Upon inspection after opening the shell, an air bubble was found in the adhesive on the back of the sensor's circuit board. To verify the feasibility of the disassembly method, two new sensor samples were disassembled using the same method. After disassembly, both new sensors functioned normally when tested at 25°C. The test data is shown in Table 14, confirming that the current disassembly method is suitable for this type of sensor.

[0213]

[0214] Table 14

[0215] After opening sample 9, the sensor was placed in a temperature chamber for testing. The temperature range of the chamber was set to 85℃ to -40℃. After disassembly, the sensor consistently output a 5V signal under different temperatures and acceleration conditions. Specific measurement values ​​are shown in Table 15.

[0216]

[0217] Table 15

[0218] To confirm the cause of the failure in sample 9, an X-ray inspection was performed. The inspection revealed cracks in the solder joints of multiple resistors. For easier understanding, the solder joints of sample 9 and a new component are compared; see example below. Figure 17 and Figure 18 ,in, Figure 17 This is an X-ray image of sample 9. Figure 18 This is an X-ray image of the new part. Figure 17 X-ray examination revealed that the solder joints of the resistor were cracked, and Figure 18No solder joint cracks were found. Circuit analysis revealed that the disconnection or poor connection of the above resistors would lead to the test results mentioned above. Therefore, it can be inferred that the failure of sample 9 was caused by cracked solder joints of the resistors. The air bubbles in the adhesive on the sensor circuit board are likely the root cause of component failure: due to abnormalities in the potting process, air bubbles appeared, and under the influence of thermal stress, the solder joints of some components were affected and failed, causing open circuits.

[0219] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0220] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A failure analysis method for a lateral acceleration sensor used in high-speed trains, characterized in that, Includes the following steps: Acquire fault data at the fault site caused by the failure of the lateral acceleration sensor in the EMU. Damage detection was performed on the appearance of all lateral acceleration sensors corresponding to the fault data to obtain sensors without external damage; Functional tests were performed on each of the sensors without visible damage at room temperature and low temperature to screen out sensor samples that failed at room temperature and sensor samples that failed at low temperature but not at room temperature. Functional tests were performed on the sensor sample that failed at low temperature but not at room temperature before disassembly and during disassembly. After disassembly, the presence of air bubbles in the potting compound was observed. When air bubbles are present in the potting adhesive of the sensor sample that failed at low temperature but not at room temperature, the potting adhesive of the sensor sample that failed at low temperature but not at room temperature is removed to obtain a de-potted sample of the sensor that failed at low temperature but not at room temperature. The adhesive-removed sample of the sensor that failed at low temperature but did not fail at room temperature was tested again at room temperature, low temperature, and low temperature to room temperature. When the sensor sample that failed at low temperature but not at room temperature passes the functional test at room temperature, fails the functional test at low temperature but passes the functional test after returning to room temperature, the sensor sample that failed at room temperature is opened for observation. When air bubbles are present in the potting compound of the room temperature failure sensor sample, the potting compound is removed to obtain a de-bonded sample of the room temperature failure sensor. The degummed sample of the room temperature failure sensor was functionally tested again at room temperature. When the de-adhesive sample of the room temperature failed the functional test at room temperature, it was inferred that the presence of air bubbles in the sensor potting adhesive was the cause of the lateral acceleration sensor failure.

2. The failure analysis method for lateral acceleration sensors used in high-speed trains according to claim 1, characterized in that, The step of performing damage detection on the appearance of all lateral acceleration sensors corresponding to the fault data to obtain sensors without external damage includes: Clean all lateral acceleration sensors corresponding to the fault data; Eliminate all lateral acceleration sensors whose plugs are missing waterproof putty; Inspect the other exterior surfaces of each lateral accelerometer with waterproof putty on the plug; When the other exterior surfaces of the lateral acceleration sensor are intact and without cracks, the internal components of the lateral acceleration sensor are treated with potting compound to eliminate the possibility of water ingress causing malfunction, resulting in a sensor without any external damage.

3. The failure analysis method for lateral acceleration sensors used in high-speed trains according to claim 1, characterized in that, The step of performing functional tests on each of the sensors without external damage at room temperature and low temperature, respectively, to screen out sensor samples that fail at room temperature and sensor samples that fail at low temperature but not at room temperature, includes: Room temperature test procedure: At room temperature, perform room temperature function test, dynamic acceleration test and vertical vibration interference test on each of the sensors without visible damage, and simultaneously record the output voltage of each sensor without visible damage. Low temperature test procedure: At low temperature, perform low temperature test on each of the sensors without visible damage, and simultaneously record the output voltage of each sensor without visible damage. Low temperature to room temperature test: After removing each of the sensors without visible damage from the low temperature, let them stand for a preset time. After returning to room temperature, perform room temperature function test, dynamic acceleration test and vertical vibration interference test on each of the sensors without visible damage. Simultaneously record the output voltage of each sensor without visible damage. Screening steps: Based on the output voltage, remove the sensors that failed during the room temperature test step, and remove the sensors that failed during the low temperature test step but became effective again during the low temperature to room temperature test step.

4. The failure analysis method for lateral acceleration sensors used in high-speed trains according to claim 3, characterized in that, The step of opening and observing the room temperature failed sensor sample includes: The metal casing of the room temperature failure sensor sample was disassembled to expose the potting compound of the room temperature failure sensor sample; The surface of the potting compound of the room temperature failure sensor sample is scanned and inspected using a surface groove scanning device to determine whether the surface of the potting compound of the room temperature failure sensor sample is flat and without grooves. If so, then there are air bubbles on the surface of the potting compound of the room temperature failure sensor sample; If not, X-ray CT scan is performed on the potting compound of the room temperature failure sensor sample to determine whether there are voids inside the potting compound of the room temperature failure sensor sample. If so, then there are air bubbles inside the potting compound of the room temperature failure sensor sample.

5. The failure analysis method for lateral acceleration sensors used in high-speed trains according to claim 1, characterized in that, The step of performing functional testing again on the degummed sample of the room temperature failed sensor at room temperature includes: At room temperature, the adhesive-removed sample of the room temperature failure sensor was subjected to room temperature function test, dynamic acceleration test and vertical vibration interference test, and the output voltage of each sensor was recorded simultaneously. Determine whether the output voltage of the sensor is the same before and after removing the potting compound from the room temperature failed sensor sample; If so, the degummed sample of the room temperature failure sensor passes the functional test at room temperature.

6. The failure analysis method for lateral acceleration sensors used in high-speed trains according to claim 1, characterized in that, The steps for performing functional tests on the sensor sample that failed at low temperatures but not at room temperature before disassembly, functional tests during disassembly, and observing whether there are air bubbles in the potting compound after disassembly include: Before disassembly, the sensor samples that failed at low temperature but not at room temperature were subjected to room temperature function tests, dynamic acceleration tests, and vertical vibration interference tests, and the output voltage of each sensor was recorded simultaneously. During the disassembly process, the sensor samples that failed at low temperature but not at room temperature were subjected to room temperature function tests, dynamic acceleration tests, and vertical vibration interference tests, and the output voltage of each sensor was recorded simultaneously. After disassembly, the surface of the potting compound of the sensor sample that failed at low temperature but not at room temperature is scanned and inspected using a surface groove scanning device to determine whether the surface of the potting compound of the sensor sample that failed at low temperature but not at room temperature is flat and without grooves. If so, then there are air bubbles on the surface of the potting compound of the sensor sample that failed at low temperature but not at room temperature; If not, X-ray CT scan is performed on the sensor sample that failed at low temperature but not at room temperature to determine whether there are voids inside the potting compound of the sensor sample that failed at low temperature but not at room temperature. If so, then there are air bubbles inside the potting compound of the sensor sample that failed at low temperature but not at room temperature.

7. The failure analysis method for lateral acceleration sensors used in high-speed trains according to claim 1, characterized in that, After the step of inferring that the presence of air bubbles in the sensor potting compound is the cause of the lateral acceleration sensor failure when the debonded sample of the room temperature-failed sensor passes the functional test at room temperature, the method further includes: The adhesive-removed sample of the room temperature failed sensor was subjected to X-ray fluoroscopic examination to obtain the first X-ray fluoroscopic detection image. Inspect and analyze the welding status of each component in the first X-ray imaging image; When the desoldering sample of the room temperature failure sensor shows signs of detachment, the detached area is treated with adhesive. The desoldering area after adhesive treatment was sliced ​​to obtain the first slice sample; The texture of the first desoldering crack at the desoldering location in the first slice sample was observed using a microscope. The failure mechanism of the lateral acceleration sensor was obtained by analyzing the texture of the first desoldering crack.

8. The failure analysis method for lateral acceleration sensors used in high-speed trains according to claim 7, characterized in that, It also includes the following steps: The adhesive-removed sample of the sensor that failed at low temperature but not at room temperature was subjected to X-ray fluoroscopic examination to obtain a second X-ray fluoroscopic detection image. The welding condition of each component in the second X-ray imaging image was examined and analyzed. When the desoldering sample of the sensor that failed at low temperature but not at room temperature shows signs of detachment, the detached area is treated with adhesive. The desoldering area after adhesive treatment was sliced ​​to obtain a second slice sample. The texture of the second weld breakage crack at the weld breakage location in the second slice sample was observed using a microscope. By comparing and analyzing the textures of the first and second desoldering cracks, the consistency of the failure mechanism of the lateral acceleration sensor is verified.

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