A method for analyzing exhaust system vibration

Abstract

The present invention provides a method for analyzing the vibration of an exhaust system, comprising the following steps: S01, constructing a modal analysis model of an engine exhaust system. S02, importing the modal analysis model into the analysis system. S03, defining the material properties of the modal analysis model in the analysis system, and adding constraint points for constraining the degrees of freedom to the part of the modal analysis model that is in a cantilever state and far away from the engine. S04, calculating the modal vibration frequency of the exhaust system, the modal vibration frequency f=K / M. Wherein K is the stiffness of the exhaust system, and M is the mass of the exhaust system. The method for analyzing the vibration of an exhaust system involved in the present invention can effectively increase the stiffness of the system while ensuring that the thermal deformation of the supercharger is not restricted. When the calculation result cannot meet the system vibration requirements, the position of the constraint point is adjusted to increase the stiffness of the system to achieve the purpose of increasing the modal vibration frequency to meet the actual production requirements.

Description

Technical Field

[0001] The invention relates to the technical field of engine exhaust system design, and in particular to a method for analyzing exhaust system vibration. Background Art

[0002] The project introduces a new type of fuel pump, aiming to find more opportunities in the market and make the engine more competitive in the market. For the fuel pump adapter, the exhaust manifold of the engine is currently equipped with exhaust parts such as superchargers, exhaust throttle valves (ETVs), and tail pipes. In order to avoid the supercharger from heating and deforming, most of the post-supercharger parts of the engines on the market are in a cantilever state. Therefore, in the actual working process, due to vibration, it is easy to cause the supercharger return pipe to crack, the tail pipe bolts to break, and other failures.

[0003] The engine exhaust system has relatively high requirements for modal frequencies. However, the current modal analysis method for the vibration of the structural system cannot provide a targeted improvement direction or a simplified improvement method to improve the vibration and noise performance of the engine body when the calculation results cannot meet the vibration requirements of the exhaust system. Summary of the invention

[0004] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a method for analyzing the vibration of the exhaust system, which can effectively increase the system stiffness without limiting the thermal deformation of the supercharger, so that the exhaust system can easily meet the vibration requirements. When the calculation results cannot meet the system vibration requirements, the position of the constraint point is adjusted to increase the system stiffness to achieve the purpose of increasing the modal vibration frequency to meet the actual production requirements, thereby effectively simplifying the analysis process and quickly solving the problem of improving the vibration and noise performance of the engine body.

[0005] In order to solve the above technical problems, the technical solution proposed by the present invention is:

[0006] A method for analyzing exhaust system vibrations, comprising the following steps: S01, constructing a modal analysis model of an engine exhaust system. S02, importing the modal analysis model into an analysis system. S03, defining the material properties of the modal analysis model in the analysis system, and adding constraint points for constraining degrees of freedom to the portion of the modal analysis model that is in a cantilever state and far away from the engine. S04, calculating the modal vibration frequency of the exhaust system, the modal vibration frequency f = K / M. Wherein K is the stiffness of the exhaust system, and M is the mass of the exhaust system.

[0007] According to the method for analyzing the vibration of the exhaust system of the present invention, by adding a constraint point on the tail pipe away from the engine body to constrain the part in the cantilever state to constrain the degree of freedom, the system stiffness can be effectively increased under the premise of ensuring that the thermal deformation of the supercharger is not restricted. Under the condition that the mass of the system itself remains unchanged, it is known that the modal vibration frequency can be effectively improved according to the modal frequency calculation formula, so that the exhaust system is easy to meet the vibration requirements. When the calculation result cannot meet the system vibration requirements, the position of the constraint point is adjusted to improve the system stiffness to achieve the purpose of increasing the modal vibration frequency to meet the actual production requirements, thereby effectively simplifying the analysis process and quickly solving the problem of improving the vibration and noise performance of the engine body, avoiding the failure of the supercharger return oil pipe cracking and the tail pipe bolt breaking, and ensuring that the product can be produced on time.

[0008] The above technical solution may be further improved as described below.

[0009] According to the method for analyzing exhaust system vibration of the present invention, in a preferred embodiment, the modal analysis model includes an exhaust manifold, a supercharger, a connecting pipe, an exhaust throttle valve and an exhaust tail pipe connected in sequence, and connecting bolts.

[0010] This modal analysis model can ensure the comprehensiveness and accuracy of the computational analysis.

[0011] Furthermore, in a preferred embodiment, the modal analysis model also includes a gasket.

[0012] This modal analysis model can further ensure the comprehensiveness and accuracy of the computational analysis.

[0013] Specifically, in a preferred embodiment, in step S03, the constraint point is located on the exhaust tail pipe.

[0014] Adding a constraint point on the tail pipe away from the engine body can further ensure that the thermal deformation of the supercharger is not restricted and can solve the problem that the cantilevered part is too long to meet the system vibration requirements, thereby further avoiding failure problems such as cracking of the supercharger return oil pipe and breakage of the tail pipe bolts.

[0015] Further, in a preferred embodiment, the restraint point is located on a connecting bolt on the exhaust tail pipe connected to the exhaust throttle valve.

[0016] The bolt constraint position of the exhaust tail pipe connected to the exhaust throttle valve belongs to the area where the system deformation is relatively large. Choosing the position with relatively large deformation is a favorable choice for the bolt constraint position. The optimization and selection of the bolt constraint position can fully constrain the system's degrees of freedom, thereby increasing the system's modal vibration frequency.

[0017] Specifically, in a preferred embodiment, the exhaust tail pipe is fixedly connected to the engine block.

[0018] This fixed connection method is beneficial to increasing the stiffness of the entire modal analysis system.

[0019] Furthermore, in a preferred embodiment, the exhaust tail pipe is connected to the engine block via a bracket.

[0020] This fixed connection method is beneficial to further increase the stiffness of the entire modal analysis system.

[0021] Specifically, in a preferred embodiment, in step S03, the constraint points are used to constrain the degrees of freedom in six directions of the portion of the modal analysis model that is in a cantilever state and away from the engine.

[0022] By performing all-round freedom constraints on the above-mentioned cantilevered part, a more comprehensive analysis and evaluation of the vibration modal analysis of the entire exhaust system can be performed, thereby obtaining a more comprehensive analysis structure to facilitate guidance of subsequent operations.

[0023] Specifically, in a preferred embodiment, in step S01 , the modal analysis model is constructed using Pro / Engineer software.

[0024] Conventional 3D modeling software is used to analyze and model the assembly model, which is convenient for conventional technical developers to operate and improves modeling efficiency.

[0025] Specifically, in a preferred embodiment, the analysis system includes ANSYS Workbench software.

[0026] The ANSYS Workbench simulation platform can be used to analyze and simulate the structural statics and structural dynamics of complex mechanical systems, thereby ensuring the accuracy of the analysis results.

[0027] Compared with the prior art, the present invention has the advantages of effectively increasing the system stiffness while ensuring that the thermal deformation of the supercharger is not restricted, so that the exhaust system can easily meet the vibration requirements. When the calculation results cannot meet the system vibration requirements, the position of the constraint point is adjusted to increase the system stiffness to achieve the purpose of increasing the modal vibration frequency to meet the actual production requirements, thereby effectively simplifying the analysis process and quickly solving the problem of improving the vibration and noise performance of the engine body. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The present invention will be described in more detail below based on embodiments and with reference to the accompanying drawings, wherein:

[0029] Figure 1The split structure of the engine exhaust system according to the embodiment of the present invention is schematically shown;

[0030] Figure 2 The modal analysis model of the engine exhaust system of the embodiment of the present invention is schematically shown;

[0031] Figure 3 The specific positions of adding constraint points in an embodiment of the present invention are schematically shown;

[0032] Figure 4 Schematically showing the vibration modal analysis calculation results of the engine exhaust system of an embodiment of the present invention;

[0033] Figure 5 The flowchart of the method for analyzing exhaust system vibration according to an embodiment of the present invention is schematically shown.

[0034] In the drawings, the same reference numerals are used for the same components. The drawings are not drawn to scale. DETAILED DESCRIPTION

[0035] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, but the protection scope of the present invention is not limited thereby.

[0036] Figure 1 The split structure of the engine exhaust system according to the embodiment of the present invention is schematically shown. Figure 2 The modal analysis model of the engine exhaust system according to the embodiment of the present invention is schematically shown. Figure 3 The specific positions of adding constraint points in the embodiment of the present invention are schematically shown. Figure 4 The vibration modal analysis calculation results of the engine exhaust system according to the embodiment of the present invention are schematically shown. Figure 5 The flowchart of the method for analyzing exhaust system vibration according to an embodiment of the present invention is schematically shown.

[0037] like Figure 5 As shown, the method for analyzing the vibration of the exhaust system of the embodiment of the present invention comprises the following steps: S01, constructing a modal analysis model of the engine exhaust system. S02, importing the modal analysis model into the analysis system. S03, defining the material properties of the modal analysis model in the analysis system, and adding constraint points for constraining the degrees of freedom to the part of the modal analysis model that is in a cantilever state and far away from the engine. S04, calculating the modal vibration frequency of the exhaust system, the modal vibration frequency f=K / M. Wherein, K is the stiffness of the exhaust system, and M is the mass of the exhaust system.

[0038] like Figure 4As shown, according to the method for analyzing the vibration of the exhaust system according to the embodiment of the present invention, by adding a constraint point on the tail pipe away from the engine body to constrain the part in the cantilever state to constrain the degree of freedom, the system stiffness can be effectively increased under the premise of ensuring that the thermal deformation of the supercharger is not restricted. Under the condition that the mass of the system itself remains unchanged, it is known that the modal vibration frequency can be effectively improved according to the modal frequency calculation formula, so that the exhaust system is easy to meet the vibration requirements. When the calculation result cannot meet the system vibration requirements, the position of the constraint point is adjusted to improve the system stiffness to achieve the purpose of increasing the modal vibration frequency to meet the actual production requirements, thereby effectively simplifying the analysis process and quickly solving the problem of improving the vibration and noise performance of the engine body, avoiding failures such as cracking of the supercharger return oil pipe and breaking of the tail pipe bolts, and ensuring that the product can be produced on time.

[0039] Specifically, in this embodiment, the modal analysis model is constructed using Pro / Engineer software in step S01. Conventional 3D modeling software is used to model the analysis assembly model, which is convenient for conventional technical developers to operate and improves modeling efficiency. Specifically, in this embodiment, the analysis system includes ANSYS Workbench software. The ANSYS Workbench simulation platform can be used to analyze and simulate the structural statics and structural dynamics of complex mechanical systems, thereby ensuring the accuracy of the analysis results.

[0040] like Figure 1 and Figure 2 As shown, specifically, in this embodiment, the modal analysis model includes an exhaust manifold 1, a supercharger 2, a connecting pipe 3, an exhaust throttle valve 4 and an exhaust tail pipe 5 connected in sequence, as well as a connecting bolt 6 and a gasket 7. This modal analysis model can ensure the comprehensiveness and accuracy of the calculation and analysis.

[0041] Specifically, in this embodiment, in step S03, the constraint point is located on the exhaust tail pipe. Adding a constraint point on the tail pipe away from the engine body can further ensure that the thermal deformation of the supercharger is not restricted and can solve the problem that the cantilevered portion is too long and cannot meet the system vibration requirements, thereby further avoiding the failure problems such as cracking of the supercharger return oil pipe and breaking of the tail pipe bolts. Further, in this embodiment, if Figure 3 As shown in the figure, the constraint point is located on the connecting bolts on the exhaust tail pipe that are connected to the exhaust throttle valve. The connecting bolt constraint position on the exhaust tail pipe that is connected to the exhaust throttle valve belongs to the area where the system deformation is relatively large. Choosing a position with relatively large deformation is a favorable choice for the bolt constraint position. The optimization and selection of the bolt constraint position can fully constrain the system's degrees of freedom, thereby increasing the system's modal vibration frequency.

[0042] Specifically, in this embodiment, in step S03, the constraint points are used to constrain the degrees of freedom in six directions of the part in the cantilever state and away from the engine on the modal analysis model. By constraining the degrees of freedom of the part in the cantilever state in all directions, a more comprehensive analysis and evaluation of the vibration modal analysis of the entire exhaust system can be performed, thereby obtaining a more comprehensive analysis structure, which is convenient for guiding subsequent operations.

[0043] Preferably, in this embodiment, the exhaust tail pipe 5 is fixedly connected to the engine cylinder block. This fixed connection method is conducive to increasing the stiffness of the entire modal analysis system. Further, in this embodiment, the exhaust tail pipe 5 is connected to the engine cylinder block through a bracket. This fixed connection method is conducive to further increasing the stiffness of the entire modal analysis system.

[0044] According to the above embodiments, it can be seen that the method for analyzing the vibration of the exhaust system according to the present invention can effectively increase the system stiffness while ensuring that the thermal deformation of the supercharger is not restricted, so that the exhaust system can easily meet the vibration requirements. When the calculation results cannot meet the system vibration requirements, the position of the constraint point is adjusted to increase the system stiffness to achieve the purpose of increasing the modal vibration frequency to meet the actual production requirements, thereby effectively simplifying the analysis process and quickly solving the problem of improving the vibration and noise performance of the engine body.

[0045] Although the present invention has been described with reference to preferred embodiments, various modifications may be made thereto and parts thereof may be replaced by equivalents without departing from the scope of the present invention. In particular, the various technical features mentioned in the various embodiments may be combined in any manner as long as there are no structural conflicts. The present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A method for analyzing exhaust system vibration, characterized in that: The steps include: S01. constructing a modal analysis model of an engine exhaust system, wherein the modal analysis model includes an exhaust manifold, a supercharger, a connecting pipe, an exhaust throttle valve and an exhaust tail pipe connected in sequence, and connecting bolts, and the modal analysis model also includes a gasket; S02, importing the modal analysis model into the analysis system; S03, defining material properties of the modal analysis model in the analysis system, and adding a constraint point for constraining the degree of freedom to a portion of the modal analysis model that is in a cantilever state and far away from the engine, wherein the constraint point is located on a connecting bolt on the exhaust tail pipe that is connected to the exhaust throttle valve; S04. Calculate the modal vibration frequency of the exhaust system, where the modal vibration frequency f=K / M; K is the stiffness of the exhaust system, and M is the mass of the exhaust system.

2. The method for analyzing exhaust system vibration according to claim 1, characterized in that: The exhaust tail pipe is fixedly connected to the engine cylinder block.

3. The method for analyzing exhaust system vibration according to claim 2, characterized in that: The exhaust tail pipe is connected to the engine cylinder block through a bracket.

4. The method for analyzing exhaust system vibration according to claim 1, characterized in that: In step S03, the constraint points are used to constrain the degrees of freedom in six directions of the part of the modal analysis model that is in a cantilever state and far away from the engine.

5. The method for analyzing exhaust system vibration according to claim 1, characterized in that: In step S01, Pro / Engineer software is used to construct a modal analysis model.

6. The method for analyzing exhaust system vibration according to claim 1, characterized in that: The analysis system includes ANSYS Workbench software.

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