Method and device for detecting vehicle exhaust system

Abstract

The present invention discloses a method and device for testing a vehicle exhaust system. The exhaust system includes a muffler and a bellows, with the muffler connected to the bellows. The method comprises: obtaining a dynamic stiffness curve formed during the vibration of the bellows, which reflects the axial dynamic stiffness corresponding to different vibration frequencies; and determining whether the resonance durability performance of the bellows is qualified based on the dynamic stiffness curve and multiple axial dynamic stiffness values ​​within the dynamic stiffness curve. By analyzing the resonance durability performance of the bellows, the method avoids axial resonance cracking of the muffler caused by axial transmission of engine excitation through the bellows, thereby ensuring that the exhaust system meets vibration requirements.

Description

Technical Field

[0001] The present invention relates to the field of vehicle technology, and in particular to a detection method and device for a vehicle exhaust system. Background Art

[0002] Exhaust noise and vibration directly impact the comfort of drivers and passengers. The exhaust system controls exhaust noise through acoustic components like mufflers and vibrations transmitted from the engine through flexible bellows. For the cold end of passenger vehicle exhaust, non-load-bearing flexible bellows can significantly reduce axial (X-direction) excitation transmitted from the engine. Exhaust durability analysis typically only considers vertical (Y / Z-direction) excitation from the road surface. Therefore, durability issues at the cold end of the exhaust system are mostly cracking caused by vertical excitation, with cracking due to axial excitation rarely occurring. However, in actual use, using existing exhaust system structure development methods, vehicle exhaust systems still fail to meet standards. Summary of the Invention

[0003] The embodiment of the present application provides a method and device for detecting a vehicle exhaust system. The method analyzes the resonance durability performance of the bellows to avoid the axial resonance cracking of the muffler caused by the axial transmission of engine excitation through the bellows, so that the exhaust system meets the vibration requirements.

[0004] In a first aspect, the present invention provides the following technical solutions through an embodiment of the present invention:

[0005] A method for detecting a vehicle exhaust system, the exhaust system comprising a muffler and a bellows, the muffler being connected to the bellows. The method comprises: obtaining a dynamic stiffness curve formed by the bellows during vibration, the dynamic stiffness curve reflecting axial dynamic stiffness corresponding to different vibration frequencies; and judging whether the resonance durability performance of the bellows is qualified based on the dynamic stiffness curve and multiple axial dynamic stiffnesses in the dynamic stiffness curve.

[0006] Preferably, if the resonance durability performance of the bellows is qualified, the modal vibration shape of the exhaust system at a preset vibration frequency is obtained; and it is determined whether the modal vibration shape has an axial drift mode, wherein the axial drift mode means that part of the modal vibration shape is in a stationary state and the other part is in an axial frequency vibration state.

[0007] Preferably, if the resonance durability performance of the bellows is unqualified, the user is prompted to update the components of the bellows.

[0008] Preferably, if the modal vibration mode exists in the modal vibration shape, the user is prompted to update the component in the exhaust system that has the axial vibration mode.

[0009] Preferably, after prompting the user to update the components with axial vibration modes in the exhaust system, the method further includes: collecting the peak frequency of the bellows and the vibration frequency of the axial vibration mode; comparing the frequency difference between the peak frequency and the vibration frequency; if the frequency difference is less than a preset frequency threshold, prompting the user to re-update the bellows components and re-update the components with axial vibration modes in the exhaust system.

[0010] Preferably, if the modal vibration mode does not exist in the axial movement mode, the road spectrum data of the muffler is collected, and the road spectrum data includes the axial strain of the muffler; based on the axial strain, the damage of the muffler is determined; based on the damage, it is determined whether the muffler has a durability risk.

[0011] Preferably, judging whether the resonance durability performance of the bellows is qualified based on the dynamic stiffness curve and the multiple axial dynamic stiffnesses in the dynamic stiffness curve includes: judging whether the resonance durability performance of the bellows is qualified by determining whether there is a peak in the dynamic stiffness curve, and comparing whether the maximum dynamic stiffness among the multiple axial dynamic stiffnesses is less than a preset dynamic stiffness threshold.

[0012] Preferably, determining whether there is a peak in the dynamic stiffness curve includes: obtaining multiple dynamic stiffnesses within a frequency range of a preset length in the dynamic stiffness curve; judging whether the difference between the minimum dynamic stiffness and the maximum dynamic stiffness among the multiple dynamic stiffnesses is greater than a dynamic stiffness difference threshold; if so, determining that there is a peak in the dynamic stiffness curve.

[0013] Preferably, the preset length is between 20 Hz and 30 Hz, and the dynamic stiffness difference threshold is between 40 N / mm and 50 N / mm.

[0014] In a second aspect, the present invention provides the following technical solution through an embodiment of the present invention:

[0015] A detection device for a vehicle exhaust system, characterized by comprising:

[0016] An acquisition module is used to acquire a dynamic stiffness curve formed by the bellows during vibration, wherein the dynamic stiffness curve reflects the axial dynamic stiffness corresponding to different vibration frequencies;

[0017] The qualification judgment module is used to judge whether the resonance durability performance of the bellows is qualified based on the dynamic stiffness curve and multiple axial dynamic stiffnesses in the dynamic stiffness curve.

[0018] In a third aspect, the present invention provides the following technical solution through an embodiment of the present invention:

[0019] An electronic device comprises: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the program, the steps of any one of the methods described in the first aspect are implemented.

[0020] In a fourth aspect, the present invention provides the following technical solution through an embodiment of the present invention:

[0021] A computer-readable storage medium stores a computer program, which, when executed by a processor, implements the steps of the method described in any one of the first aspects above.

[0022] One or more technical solutions provided in the embodiments of this application have at least the following technical effects or advantages:

[0023] The embodiment of the present invention provides a detection method for a vehicle exhaust system, wherein the exhaust system includes a muffler and a bellows, and the muffler is connected to the bellows. The method includes: obtaining a dynamic stiffness curve formed by the bellows during vibration, wherein the dynamic stiffness curve reflects the axial dynamic stiffness corresponding to different vibration frequencies; and judging whether the resonance durability performance of the bellows is qualified based on the dynamic stiffness curve and the multiple axial dynamic stiffnesses in the dynamic stiffness curve. The present application takes into account the axial dynamic stiffness generated by the bellows during vibration, and optimizes the resonance durability performance of the bellows according to the dynamic stiffness curve generated by the bellows, so that the dynamic stiffness curve of the bellows meets the requirements, thereby fundamentally avoiding the problem of engine excitation being transmitted axially through the bellows, thereby causing axial resonance cracking of the muffler. The optimization method is simple and effective, and does not add too much extra workload compared to the normal exhaust system structure development process. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following is a brief introduction to the drawings required for use in the description of the embodiments. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0025] Figure 1 A flow chart of a vehicle exhaust system detection method provided by an embodiment of the present invention;

[0026] Figure 2 A schematic diagram of a bellows optimized front dynamic stiffness curve provided by an embodiment of the present invention;

[0027] Figure 3 A schematic diagram of the 3D structure of the exhaust system provided in an embodiment of the present invention;

[0028] Figure 4 A schematic diagram of the system modal vibration shape of the muffler end cover before optimization provided by an embodiment of the present invention;

[0029] Figure 5 A schematic diagram of the system modal vibration shape of the optimized muffler end cover provided in an embodiment of the present invention;

[0030] Figure 6 A schematic structural diagram of a vehicle exhaust system detection device provided by an embodiment of the present invention;

[0031] Figure 7 A schematic structural diagram of an electronic device provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0032] The inventors discovered that conventional methods for developing exhaust system structures primarily consider durability when selecting bellows, with stiffness requirements for vibration reduction being a secondary consideration. Peak stiffness and frequency are also ignored. Exhaust system constrained modes focus solely on avoiding the engine's idle ignition frequency. Road spectra are collected only from the YZ (vertical) torsional strain of road excitation. However, analysis revealed that the bellows do not fully isolate engine excitation. In reality, the bellows not only bend and torsion in the vertical direction, but also experience axial vibration (i.e., vibration from the front to the rear of the vehicle), further contributing to axial resonance cracking in the muffler.

[0033] In view of this, an embodiment of the present application provides a detection method and device for a vehicle exhaust system. The method analyzes the resonance durability performance of the bellows to avoid the axial resonance cracking of the muffler caused by the axial transmission of engine excitation through the bellows, so that the exhaust system meets the vibration requirements.

[0034] The overall idea of ​​the technical solution of the embodiment of this application is as follows:

[0035] A method for detecting a vehicle exhaust system, the exhaust system comprising a muffler and a bellows, the muffler being connected to the bellows. The method comprises: obtaining a dynamic stiffness curve formed by the bellows during vibration, the dynamic stiffness curve reflecting axial dynamic stiffness corresponding to different vibration frequencies; and judging whether resonance durability performance of the bellows is qualified based on the dynamic stiffness curve and multiple axial dynamic stiffnesses in the dynamic stiffness curve.

[0036] In order to better understand the above technical solution, the above technical solution will be described in detail below with reference to the accompanying drawings and specific implementation methods.

[0037] In a first aspect, an embodiment of the present invention provides a method for detecting a vehicle exhaust system, wherein the exhaust system includes a muffler and a bellows, wherein the muffler is connected to the bellows. Specifically, Figure 1 As shown, the method includes the following steps S101 to S102.

[0038] Step S101, obtaining a dynamic stiffness curve formed by the bellows during vibration, wherein the dynamic stiffness curve reflects the axial dynamic stiffness corresponding to different vibration frequencies;

[0039] Step S102 : judging whether the resonance durability performance of the bellows is qualified based on the dynamic stiffness curve and the multiple axial dynamic stiffnesses.

[0040] In a specific implementation, a method for obtaining a dynamic stiffness curve formed by a bellows during vibration may include calculating the axial dynamic stiffness of the exhaust system using a modal frequency response analysis method to obtain a dynamic stiffness curve, wherein the dynamic stiffness curve includes the relationship between frequency and axial dynamic stiffness. Alternatively, a fatigue testing machine may be used to obtain the axial dynamic stiffness corresponding to different vibration frequencies to obtain a dynamic stiffness curve. Axial dynamic stiffness refers to the bellows' ability to resist deformation along the axial centerline.

[0041] Based on the dynamic stiffness curve and multiple axial dynamic stiffnesses in the dynamic stiffness curve, judging whether the resonance durability performance of the bellows is qualified can specifically include: judging whether the resonance durability performance of the bellows is qualified by determining whether there is a peak in the dynamic stiffness curve, and comparing whether the maximum dynamic stiffness among multiple axial dynamic stiffnesses is less than a preset dynamic stiffness threshold.

[0042] Specifically, if the maximum dynamic stiffness is greater than a preset dynamic stiffness threshold and / or the dynamic stiffness curve exhibits a peak, the bellows' resonance durability performance is deemed unqualified. If the maximum dynamic stiffness within the axial dynamic stiffness is less than a preset dynamic stiffness threshold and the dynamic stiffness curve exhibits no peak, the bellows' resonance durability performance is deemed qualified. It should be noted that the presence of a peak in the dynamic stiffness curve indicates that the bellows is easily excited and exhibits high dynamic stiffness. Therefore, preventing the bellows from being excited by the engine can effectively prevent axial resonance in the bellows, which can lead to resonance cracking in the muffler.

[0043] In a specific embodiment, determining whether the maximum dynamic stiffness among multiple axial dynamic stiffnesses is less than a preset dynamic stiffness threshold includes: when the vibration frequency of the exhaust system is within a preset vibration frequency range, determining whether the maximum dynamic stiffness among multiple axial dynamic stiffnesses is less than the preset dynamic stiffness threshold.

[0044] Among them, the preset vibration frequency range is set according to the engine speed (idle speed and maximum speed). Therefore, it can be concluded that the preset vibration frequency range can be 20 HZ-200 HZ. Of course, in other embodiments, the preset vibration frequency range can also be: 0 HZ-200 HZ, etc.

[0045] For example, the preset dynamic stiffness threshold can be 100 N / mm. Only when the dynamic stiffness is below 100 N / mm, it is said that the dynamic stiffness of the bellows is qualified. Of course, the preset dynamic stiffness threshold can also be other values, such as 90 N / mm, 95 N / mm, etc., which is not limited in this application.

[0046] As an optional embodiment, determining whether there is a peak in the dynamic stiffness curve may include: obtaining multiple dynamic stiffnesses within a frequency interval of a preset length in the dynamic stiffness curve; determining whether the difference between the minimum dynamic stiffness and the maximum dynamic stiffness among the multiple dynamic stiffnesses is greater than a dynamic stiffness difference threshold; if so, determining that there is a peak in the dynamic stiffness curve.

[0047] Specifically, when the vibration frequency of the exhaust system is within a preset vibration frequency range, multiple dynamic stiffnesses within a frequency interval of a preset length in the dynamic stiffness curve are obtained, and it is determined whether the difference between the minimum dynamic stiffness and the maximum dynamic stiffness among the multiple dynamic stiffnesses is greater than a dynamic stiffness difference threshold.

[0048] Among them, the frequency interval of the preset length can be determined according to actual needs, for example: it can be a frequency interval with a length of 20HZ to 30Hz. Taking 20HZ as an example here, the frequency interval with a length of 20HZ can be: 0 to 20HZ, 1 HZ to 21HZ, 20HZ to 40HZ, etc.; the dynamic stiffness difference threshold can also be determined according to actual conditions, for example: between 40N / mm and 50N / mm.

[0049] Specifically, determining whether the maximum dynamic stiffness among multiple axial dynamic stiffnesses is less than a preset dynamic stiffness threshold, and determining whether there is a peak in the dynamic stiffness curve may include: determining whether the maximum axial dynamic stiffness among multiple axial dynamic stiffnesses is less than 100 N / mm when the vibration frequency of the exhaust system is between 20 Hz and 200 Hz, and determining whether the difference between the minimum dynamic stiffness and the maximum dynamic stiffness among multiple dynamic stiffnesses within the frequency range of 20 Hz in the dynamic stiffness curve is greater than 40 N / mm when the vibration frequency is between 20 Hz and 200 Hz.

[0050] If it is determined that when the vibration frequency is between 20 Hz and 200 Hz, the maximum axial dynamic stiffness among the axial dynamic stiffnesses is greater than or equal to 100 N / mm, and / or it is determined that when the vibration frequency is between 20 Hz and 200 Hz, the difference between the minimum dynamic stiffness and the maximum dynamic stiffness among the multiple dynamic stiffnesses within the frequency range of 20 Hz in the dynamic stiffness curve is greater than 40 N / mm, then it is determined that the resonance durability performance of the bellows is unqualified.

[0051] Of course, as another optional embodiment, determining whether there is a peak in the dynamic stiffness curve in the present application may further include: determining whether the difference between the maximum dynamic stiffness and the minimum dynamic stiffness on the dynamic stiffness curve is greater than a dynamic stiffness difference threshold.

[0052] If the resonance durability performance of the bellows is determined to be unqualified, the user is prompted to update the bellows components until the resonance durability performance of the bellows is determined to be qualified. Specifically, the component update method may include redesigning the bellows material, bellows structure (including corrugation shape and number of corrugation layers), geometric dimensional parameters, i.e., performance parameters, etc. This application does not limit the specific method for optimizing the bellows.

[0053] This application has conducted corresponding tests and judgments on the bellows at the physical stage, such as Figure 2 The following diagram shows the dynamic stiffness curves of the bellows before and after the aforementioned component upgrade. The figure shows that before the upgrade (optimization), the maximum axial dynamic stiffness of the bellows was 150 N / mm, and the dynamic stiffness curve had a peak at 83 Hz. Therefore, the bellows' resonance durability did not meet the requirements. After the optimized design, the maximum axial dynamic stiffness of the bellows was less than or equal to 70 Hz, and the dynamic stiffness curve had no obvious peak.

[0054] Therefore, this application analyzes the axial dynamic stiffness and dynamic stiffness curve of the bellows to determine whether there is an axial transmission problem in the bellows, and effectively avoids the occurrence of axial resonance cracking of the muffler caused by the axial transmission of the bellows by changing the axial transmission problem of the bellows caused by the engine excitation.

[0055] Furthermore, if the analysis shows that the resonance durability performance of the bellows is qualified, the exhaust system structure can be simulated and confirmed to analyze the modal vibration shape of the exhaust system, thereby optimizing the exhaust system and further eliminating the axial resonance cracking problem of the muffler.

[0056] Specifically, the method may also include: step S201, if the resonance durability performance of the bellows is qualified, then obtaining the modal vibration shape of the exhaust system at a preset vibration frequency; step S202, judging whether the modal vibration shape has an axial drift mode, wherein the axial drift mode refers to a part of the modal vibration shape being in a stationary state and the other part being in an axial frequency vibration state.

[0057] It should be noted that the axial frequency in this application refers to the frequency of the exhaust system from the front to the rear of the vehicle.

[0058] In a specific embodiment, a modal analysis model of the exhaust system is first established. This modal analysis model is then imported into a pre-set analysis system to obtain the modal vibration shapes of the exhaust system at a pre-set vibration frequency. Specifically, the modal analysis model of the exhaust system can be constructed using Pro / Engineer software (e.g., a finite element model), and the analysis and assembly model can be constructed using 3D modeling software. The pre-set analysis system can include ANSYS Workbench software.

[0059] In a specific embodiment, the material properties of the finite element model and the constraint points of the finite element model can be set to obtain the constrained modes of the exhaust system. Based on the preset analysis system, the modal vibration shapes of the exhaust system constrained modes within the preset vibration frequency range are analyzed to determine whether the modal vibration shapes of the exhaust system within this frequency range contain axial drift modes. If the modal vibration shapes do not contain axial drift modes, the exhaust system is determined to be qualified, that is, it has passed the design phase of the axial resonance prevention durability plan; if the modal vibration shapes contain axial drift modes, the exhaust system is determined to be unqualified, and the user is prompted to update the components in the exhaust system that contain axial drift modes. For example, the preset vibration frequency range is from 20 Hz to 200 Hz.

[0060] In this application, the dynamic characteristics of the axial vibration mode in the modal vibration shape are: the exhaust system starts from a certain local place, and the movement is divided into two parts, one part is stationary, and the other part moves axially from the local area as a whole. The vibration position is at the rear end cover of the front muffler (visible Figure 3 Ellipse range S). Figure 4 、 6 As shown in the figure, it is the simulation diagram before and after the exhaust system optimization. Figure 4 and Figure 5 It can be seen from point a in the figure that before the exhaust system is optimized, the muffler has obvious axial movement when the vibration frequency is between 89HZ and 112HZ. After the exhaust system is optimized, the axial movement of the muffler is eliminated when the vibration frequency is between 50HZ and 110HZ.

[0061] If it is determined that the exhaust system has an axial shift mode, the user is prompted to update the components in the exhaust system that have the axial shift mode until the exhaust system has no axial shift mode. Specifically, the component update process may include: optimizing the end cap of the muffler.

[0062] As an optional embodiment, the shape of the muffler end cover can be optimized to make the exhaust system free of axial drift modes. For example, the original planar structure of the end cover can be changed to an end cone structure.

[0063] Specifically, when the muffler end cap is changed from a flat structure to an end cone, the structure of the muffler is strengthened, which helps eliminate the oscillation mode. Of course, as other optional embodiments, the exhaust system structure can also be strengthened and optimized by changing the flat structure to a spherical structure, or by adding counterweights to the exhaust system.

[0064] Of course, as another optional embodiment, the exhaust system may be made free of axial movement modes by optimizing other components of the muffler, which is not limited in this application.

[0065] This application conducted corresponding tests and judgments on the modal vibration shapes of the exhaust system at the physical stage, such as Figure 6 The figure shows the system modal vibration mode before the optimization of the muffler end cover. It can be seen from the figure that before the optimization of the exhaust system, the exhaust system has a vibration mode at 83.7HZ in the modal test under the actual vehicle assembly. Therefore, the exhaust system does not meet the axial resonance durability requirements. Figure 7 The figure shows the schematic diagram of the system modal vibration shape after the optimization of the muffler end cover. After optimizing the end cover structure of the front muffler, the modified exhaust system has no axial vibration mode.

[0066] In a specific embodiment, if the above process cannot make the resonance durability performance of the bellows and the axial vibration mode of the exhaust system qualified due to other design boundary restrictions, that is, after updating the components of the resonance durability performance of the bellows and updating the components with axial vibration modes in the exhaust system, the axial resonance cracking problem of the muffler is not eliminated, then further testing can be performed after completing steps S101~102 and steps S201~202.

[0067] In a specific embodiment, after prompting the user to update components in the exhaust system that exhibit axial oscillation modes, the method may further include: step S301, collecting the peak frequency of the bellows and the oscillation frequency of the axial oscillation mode; comparing the frequency difference between the peak frequency and the oscillation frequency; and step S302, if the frequency difference is less than a preset frequency threshold, prompting the user to re-optimize the resonance durability performance of the bellows and re-update the components in the exhaust system that exhibit axial oscillation modes. The oscillation frequency represents the vibration frequency corresponding to the presence of the axial oscillation mode in the simulation graph.

[0068] Specifically, the peak frequency of the bellows is obtained by obtaining the dynamic stiffness curve of the bellows, and the frequency of the axial vibration mode of the exhaust system is obtained by obtaining the simulation test; the difference between the peak frequency of the bellows and the axial vibration frequency is compared to see whether it is less than the preset frequency threshold. If so, the muffler resonance durability risk in the current exhaust system is relatively high. At this time, it is necessary to re-optimize the bellows and the exhaust system components to achieve re-optimization of the dynamic stiffness of the bellows and the constraint mode of the exhaust system until the frequency difference is greater than or equal to the preset frequency threshold; if the comparison shows that the frequency difference is greater than the preset frequency threshold, the muffler resonance durability design in the current exhaust system is qualified.

[0069] The preset frequency threshold may be set according to actual needs. For example, in this embodiment, the preset frequency threshold may be 15 Hz.

[0070] In a specific embodiment, after comparing whether the frequency difference between the peak frequency of the bellows and the vibration frequency is less than a preset frequency threshold, the present application may also include: conducting actual vehicle verification on the bellows and the exhaust system, conducting dynamic stiffness testing on the actual bellows, and performing constrained modal testing on the exhaust system. After analysis and judgment according to the above steps S101~102, steps S201~202 and steps S301~302, it is concluded that the simulation results are slightly different from the actual test results.

[0071] Furthermore, during the vehicle verification phase, this application can also conduct a durability risk assessment on the muffler to verify whether the muffler's durability risk design is qualified. In a specific embodiment, if it is determined that the modal vibration mode does not have an axial drift mode, the method can also include: collecting road spectrum data of the muffler, the road spectrum data including the axial strain of the muffler; determining damage to the muffler based on the axial strain; and determining whether the muffler has a durability risk based on the damage.

[0072] Specifically, a strain gauge is arranged on the end face of the muffler in the present application. The setting direction of the strain gauge is perpendicular to the vertical direction (YZ) of the muffler and is used to collect the axial (X) strain of the muffler.

[0073] Specifically, by adding axial strain data to the exhaust system's road spectrum data collection, the collected road spectrum data is converted into stress, and the muffler damage is statistically calculated using the rain flow method. The damage is then used to determine whether the muffler has a durability risk. Alternatively, a durability safety factor is calculated by combining the bench limit destructive force and the road spectrum equivalent force under the same damage, and the muffler's durability risk is then assessed using the safety factor. The bench limit destructive force here can be 1 million times the bench limit destructive force, and both the bench limit destructive force and the road spectrum equivalent force under the same damage can be obtained through testing.

[0074] Determining whether a muffler presents a durability risk based on damage involves determining whether the damage falls within a pre-set damage safety range. If not, the muffler end face is considered to be at risk. For example, if the damage is less than 10%, or if the safety factor is greater than 1.5, the muffler is considered to have a qualified durability risk.

[0075] It should be noted that, in order to ensure the accuracy of the road spectrum data collection during actual road spectrum collection, the influence of temperature can also be taken into account, so the strain gauge here can be a high-temperature strain gauge.

[0076] After collecting real-vehicle road records, this application conducted a durability safety factor analysis. After on-vehicle verification testing, it was concluded that the safety factor for a flat end cap was 0.69, the safety factor for an optimized bellows was 1.02, and the safety factor for an optimized muffler end cap was 6.7. The combined safety factor of the two optimization schemes was greater than 6.7. After comprehensively considering the feasibility and cost of the schemes, the optimized end cap was ultimately chosen.

[0077] During the actual vehicle durability test, the original scheme and the optimized end cover scheme were compared, and it was found that the original scheme had cracking, while the optimized scheme had no problems, which was consistent with the conclusion of the durability analysis.

[0078] Therefore, the detection method of the vehicle exhaust system provided in the present application specifically includes: analyzing and determining the dynamic stiffness curve of the bellows, and optimizing the resonance durability performance of the bellows; performing constrained modal analysis on the exhaust system to determine whether there is an axial drift mode in the exhaust system; then comparing and determining the frequency difference between the peak frequency of the bellows and the drift frequency of the axial drift mode of the exhaust system to determine whether the bellows and the exhaust system should be re-optimized; confirming the difference between the dynamic stiffness, modal vibration shape and frequency difference verified by the actual object and the dynamic stiffness, modal vibration shape and frequency difference obtained by the simulation test; collecting road spectrum data (including axial strain) of the exhaust system, and performing durability risk analysis based on the collected road spectrum data.

[0079] In summary, the embodiment of the present invention can effectively improve the problem of axial resonance cracking of the muffler caused by engine excitation by adding a method for preventing the problem of axial resonance cracking of the muffler, so that the exhaust system meets the vibration requirements. The method is simple and does not increase too much additional workload compared to the normal exhaust system structure development process.

[0080] In the second aspect, based on the same inventive concept, this embodiment provides a detection device for a vehicle exhaust system, such as Figure 6 As shown, including:

[0081] An acquisition module 401 is used to acquire a dynamic stiffness curve formed by the bellows during vibration, where the dynamic stiffness curve reflects the axial dynamic stiffness corresponding to different vibration frequencies;

[0082] The qualification judgment module 402 is used to judge whether the resonance durability performance of the bellows is qualified based on the dynamic stiffness curve and multiple axial dynamic stiffnesses in the dynamic stiffness curve.

[0083] As an optional embodiment, if the resonance durability performance of the bellows is qualified, the device further includes:

[0084] a modal vibration shape acquisition module, configured to acquire the modal vibration shape of the exhaust system at a preset vibration frequency;

[0085] The axial vibration mode judgment module is used to judge whether the modal vibration mode has an axial vibration mode, wherein the axial vibration mode refers to that part of the modal vibration mode is in a static state and the other part is in an axial vibration state.

[0086] As an optional embodiment, if the resonance durability performance of the bellows is unqualified, the user is prompted to update the components of the bellows.

[0087] As an optional embodiment, if the modal vibration mode exists in the modal vibration mode, the user is prompted to update the components in the exhaust system that have the axial vibration mode.

[0088] As an optional embodiment, the device further includes:

[0089] Frequency acquisition module, used to collect the peak frequency of the bellows and the vibration frequency of the axial vibration mode;

[0090] A comparison module for comparing the frequency difference between the peak frequency and the oscillation frequency;

[0091] The third updating module is used to prompt the user to re-update the components of the bellows and re-update the components in the exhaust system that have axial movement modes if the frequency difference is less than a preset frequency threshold.

[0092] As an optional embodiment, if the modal vibration mode does not have an axial movement mode, the device further includes:

[0093] A road spectrum data acquisition module is used to collect the road spectrum data of the muffler, and the road spectrum data includes the axial strain of the muffler;

[0094] A damage determination module is used to determine the damage of the muffler based on the axial strain;

[0095] The durability risk judgment module is used to determine whether the muffler has a durability risk based on damage.

[0096] As an optional embodiment, the qualification judgment module 502 is specifically used to judge whether the resonance durability performance of the bellows is qualified by determining whether there is a peak in the dynamic stiffness curve and comparing whether the maximum dynamic stiffness among the multiple axial dynamic stiffnesses is less than a preset dynamic stiffness threshold.

[0097] As an optional embodiment, determining whether there is a peak in the dynamic stiffness curve includes: obtaining multiple dynamic stiffnesses in the dynamic stiffness curve within a frequency range of a preset length; judging whether the difference between the minimum dynamic stiffness and the maximum dynamic stiffness among the multiple dynamic stiffnesses is greater than a dynamic stiffness difference threshold; if so, determining that there is a peak in the dynamic stiffness curve.

[0098] As an optional embodiment, the preset length is between 20 Hz and 30 Hz, and the dynamic stiffness difference threshold is between 40 N / mm and 50 N / mm.

[0099] The above modules can be implemented by software codes, in which case the above modules can be stored in the memory of the control device. The above modules can also be implemented by hardware such as integrated circuit chips.

[0100] An embodiment of the present invention provides a detection device for a vehicle exhaust system, the implementation principle and technical effects of which are the same as those of the aforementioned method embodiment. For the sake of brief description, for matters not mentioned in the device embodiment, reference may be made to the corresponding contents in the aforementioned method embodiment.

[0101] In a third aspect, based on the same inventive concept, this embodiment provides an electronic device 500, such as Figure 7 As shown, it includes: a memory 501, a processor 502 and a computer program 503 stored in the memory and executable on the processor. When the processor 501 executes the program, the steps of the vehicle exhaust system detection method described in the first aspect are implemented.

[0102] Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0103] Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if such changes and modifications fall within the scope of the claims and their equivalents, the present invention is intended to include such changes and modifications.

Claims

1. A method for detecting a vehicle exhaust system, characterized in that: The exhaust system includes a muffler and a bellows, wherein the muffler is connected to the bellows, and the method includes: Obtaining a dynamic stiffness curve formed by the bellows during vibration, wherein the dynamic stiffness curve reflects the axial dynamic stiffness corresponding to different vibration frequencies; Based on the dynamic stiffness curve and multiple axial dynamic stiffnesses in the dynamic stiffness curve, judging whether the resonance durability performance of the bellows is qualified; If the resonance durability performance of the bellows is qualified, obtaining the modal vibration shape of the exhaust system at a preset vibration frequency; Determine whether the modal vibration mode has an axial shifting mode, wherein the axial shifting mode means that a part of the modal vibration mode is in a stationary state and the other part is in an axial frequency shifting state.

2. The detection method according to claim 1, wherein If the resonance durability performance of the bellows is unqualified, the user is prompted to replace the components of the bellows.

3. The detection method according to claim 1, wherein If the modal vibration mode exists in the axial vibration mode, the user is prompted to update the component in the exhaust system that has the axial vibration mode.

4. The detection method according to claim 3, wherein After prompting the user to update the component in the exhaust system that has the axial movement mode, the method further includes: Collecting the peak frequency of the bellows and the vibration frequency of the axial vibration mode; comparing a frequency difference between the peak frequency and the oscillation frequency; If the frequency difference is less than a preset frequency threshold, the user is prompted to re-update the components of the bellows and re-update the components in the exhaust system that have axial movement modes.

5. The detection method according to claim 1, wherein If the modal vibration mode does not have an axial movement mode, collecting the road spectrum data of the muffler, the road spectrum data including the axial strain of the muffler; determining damage to the muffler based on the axial strain; Based on the damage, it is determined whether the muffler has a durability risk.

6. The detection method according to claim 1, wherein The determining whether the resonance durability performance of the bellows is qualified based on the dynamic stiffness curve and the multiple axial dynamic stiffnesses in the dynamic stiffness curve includes: Whether the resonance durability performance of the bellows is qualified is determined by determining whether there is a peak in the dynamic stiffness curve and comparing whether the maximum dynamic stiffness among the multiple axial dynamic stiffnesses is less than a preset dynamic stiffness threshold.

7. The detection method according to claim 6, wherein Determining whether the dynamic stiffness curve has a peak includes: Acquiring a plurality of dynamic stiffnesses within a frequency interval of a preset length in the dynamic stiffness curve; It is determined whether a difference between a minimum dynamic stiffness and a maximum dynamic stiffness among the multiple dynamic stiffnesses is greater than a dynamic stiffness difference threshold; if so, it is determined that a peak exists in the dynamic stiffness curve.

8. The detection method according to claim 7, wherein The preset length is between 20 Hz and 30 Hz, and the dynamic stiffness difference threshold is between 40 N / mm and 50 N / mm.

9. A detection device for a vehicle exhaust system, characterized in that: include: An acquisition module is used to acquire a dynamic stiffness curve formed by the bellows during vibration, wherein the dynamic stiffness curve reflects the axial dynamic stiffness corresponding to different vibration frequencies; a qualification judgment module, configured to judge whether the resonance durability performance of the bellows is qualified based on the dynamic stiffness curve and a plurality of axial dynamic stiffnesses in the dynamic stiffness curve; a modal vibration shape acquisition module, configured to acquire the modal vibration shape of the exhaust system at a preset vibration frequency; The axial vibration mode judgment module is used to judge whether the modal vibration mode has an axial vibration mode, wherein the axial vibration mode refers to that part of the modal vibration mode is in a static state and the other part is in an axial vibration state.

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