Method for modal testing of an automotive intake system

Abstract

This invention discloses a modal testing method for an automotive intake system, comprising: installing an electromagnetic excitation device in the intake duct to drive a movable part to generate pressure pulsations through a periodic electromagnetic field to apply simulated excitation; establishing a correspondence between the excitation frequency and the electromagnetic excitation signal based on the engine speed, generating a corresponding excitation signal to achieve multi-frequency range pulsation excitation; arranging vibration response sensors and pressure sensors at at least two structural locations in the intake system to collect vibration and pressure signals; processing the signals to extract frequency response information and identify modal parameters to obtain modal characteristics. This invention can accurately reproduce the gas pulsation characteristics under actual operating conditions, avoid the fluctuation errors of traditional aerodynamic excitation, simplify the testing process, and quickly adjust parameters by combining sensor feedback, thereby improving the accuracy and efficiency of modal analysis.

Description

Technical Field

[0001] This invention belongs to the field of automotive intake system noise and vibration testing technology. Specifically, this invention relates to a modal testing method for automotive intake systems. Background Technology

[0002] With the rapid development and technological advancements in the automotive industry, passengers have increasingly higher demands for the driving and riding experience. Noise is a significant factor affecting passenger comfort and speech intelligibility. For both traditional gasoline-powered and hybrid vehicles, the roaring sound of the intake system is one of the main sources of in-vehicle noise, caused by the acoustic modes of the intake system. Therefore, reducing intake system noise and studying its acoustic modal characteristics has become an important research topic for many automakers.

[0003] Currently, there are two main traditional testing methods for the modal characteristics of intake systems: one is the acoustic excitation test method, which uses sound waves such as volumetric sound sources for excitation, i.e., a loudspeaker is placed at the intake port to emit sound sources for excitation, and several microphones are placed between the intake pipe opening and the manifold to receive the sound pressure response; the other is the mechanical excitation test method, which uses mechanical excitation such as force hammers or vibrators, i.e., several vibration acceleration sensors are placed on the surface of the intake pipe, force hammers or vibrators are used for excitation, and the vibration response is obtained through vibration sensors.

[0004] These two testing methods are insufficient to accurately simulate the gas pulsation effect caused by the periodic opening and closing of the engine intake valves, and have the following shortcomings: (1) Mechanical excitation cannot reproduce the randomness and broadband characteristics of gas pulsation; (2) Acoustic excitation is susceptible to interference from environmental noise; (3) The test results deviate significantly from the actual working conditions.

[0005] This paper provides a modal testing method for automotive intake systems, specifically focusing on how to evaluate the dynamic characteristics of intake systems under near-realistic operating conditions. This provides accurate data support for the optimized design of intake systems and improves the accuracy of test results. Summary of the Invention

[0006] This invention aims to at least solve one of the technical problems existing in the prior art. To this end, this invention provides a modal testing method for an automotive intake system, with the purpose of evaluating the dynamic characteristics of the intake system under near-realistic operating conditions, providing accurate data support for the optimized design of the intake system, and improving the accuracy of test results.

[0007] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a modal testing method for an automotive intake system, comprising the following steps: S1: An electromagnetic excitation device is installed at the intake pipe position of the automobile intake system. The electromagnetic excitation device generates a periodically changing electromagnetic field to drive the movable parts that cooperate with the intake channel to form pressure pulsation, thereby applying simulated gas pulsation excitation to the intake system. S2: Based on the engine speed, establish the correspondence between the excitation frequency of the pressure pulsation and the electromagnetic excitation signal, and generate the electromagnetic excitation signal according to the correspondence to achieve pulsation excitation in different frequency ranges; S3: By arranging vibration response sensors and pressure sensors at at least two structural locations in the intake system, vibration signals and pressure signals of the intake system under the pulsating excitation are collected respectively. S4: Process the collected vibration and pressure signals to extract the frequency response information of the intake system, and perform modal parameter identification based on the frequency response information to obtain the modal characteristics of the intake system.

[0008] The electromagnetic excitation device includes multiple electromagnetic coils arranged circumferentially along the intake pipe, and the multiple electromagnetic coils constitute an electromagnetic excitation array surrounding the intake pipe.

[0009] The electromagnetic excitation array is disposed in the throat region of the intake duct and is installed on the outside of the intake duct by a fixed structure so that the electromagnetic excitation acts on the intake channel position corresponding to the throat region.

[0010] The plurality of electromagnetic coils are each connected to an independent control channel to adjust the excitation phase and excitation amplitude of each electromagnetic coil.

[0011] The movable component is a magnetic piston disposed in the air intake channel. The magnetic piston reciprocates along the axial direction of the air intake channel under the action of an electromagnetic field to form the pressure pulsation.

[0012] The relationship between the excitation frequency and the engine speed is established by a lookup table or a function mapping method.

[0013] The frequency range of the pulsed excitation covers 20Hz to 200Hz, and scanning tests are performed by setting a frequency step mode.

[0014] The vibration response sensor is an acceleration sensor, which is arranged on the outer surface of the air filter and / or resonant cavity of the intake system.

[0015] The vibration response sensor is a non-contact sound pressure sensor.

[0016] The vibration and pressure signals are synchronously acquired through the same data acquisition system and time-aligned based on a unified time reference. The collected data is processed in the time domain and frequency domain to obtain the frequency response function; The modal parameter identification includes identifying modal frequencies based on a frequency domain decomposition method and reconstructing the corresponding mode shapes.

[0017] The modal testing method for automotive intake systems of the present invention has the following advantages: (1) High-precision simulation: Electromagnetic excitation can accurately reproduce the gas pulsation characteristics under actual working conditions, avoiding the fluctuation error of traditional pneumatic excitation.

[0018] (2) Simplified testing process: No complex pneumatic equipment is required; controllable excitation signals are generated directly through electromagnetic coils.

[0019] (3) Dynamic response optimization: Combine sensor feedback to quickly adjust excitation parameters and improve the accuracy and efficiency of modal analysis. Attached Figure Description

[0020] Figure 1 This is a diagram showing the connection of the data acquisition equipment; Figure 2 This is a schematic diagram showing the placement of the vibration response sensors; Figure 3 This is a schematic diagram of an electromagnetic coil structure; Figure 4 This is a flowchart of the modal testing method for the automotive intake system of the present invention; The markings in the above figures are as follows: 1. Intake system; 2. Electromagnetic excitation device; 3. Vibration response sensor; 4. Pressure sensor; 5. Power amplifier; 6. Data acquisition system; 7. Analysis system; 8. Resonant cavity; 9. Intake pipe; 10. Air filter; 11. Magnetic piston; 12. Electromagnetic coil; 13. Clamp. Detailed Implementation

[0021] To facilitate understanding of the present invention, a more comprehensive description of the present invention will be given below with reference to the accompanying drawings, which illustrate several embodiments of the present invention. However, the present invention can be implemented in different forms and is not limited to the embodiments described in the text. Rather, these embodiments are provided to make the disclosure of the present invention more thorough and complete.

[0022] It should be noted that when an element is referred to as being "fixed to" another element, it can be directly on the other element or there may be an intervening element. When an element is referred to as being "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," and similar expressions used in this document are for illustrative purposes only.

[0023] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly associated with those skilled in the art to which this invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments and is not intended to limit the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0024] like Figures 1 to 3 As shown, this embodiment of the invention provides a modal testing method for an automotive intake system, comprising the following steps: S1: An electromagnetic excitation device 2 is installed at the intake pipe 9 of the automobile intake system. The electromagnetic excitation device 2 generates a periodically changing electromagnetic field to drive the movable parts that cooperate with the intake channel to form pressure pulsation, thereby applying simulated gas pulsation excitation to the intake system. S2: Based on the engine speed, establish the correspondence between the excitation frequency of pressure pulsation and the electromagnetic excitation signal, and generate the electromagnetic excitation signal according to the correspondence to achieve pulsation excitation in different frequency ranges; S3: Vibration response sensor 3 and pressure sensor 4 are arranged at at least two structural locations in the intake system to collect vibration signals and pressure signals of the intake system under pulsating excitation, respectively. S4: Process the collected vibration and pressure signals, extract the frequency response information of the intake system, and perform modal parameter identification based on the frequency response information to obtain the modal characteristics of the intake system.

[0025] Specifically, this invention relates to the field of automotive intake system noise and vibration testing technology, and more specifically to a method for modal testing of an automotive intake system using electromagnetic excitation to simulate gas pulsation excitation. This method is particularly suitable for evaluating the dynamic characteristics of the intake system under near-realistic operating conditions, providing accurate data support for the optimized design of the intake system, and both approximating the real dynamic characteristics of the intake system and reducing the influence of the environment on the test results.

[0026] In this embodiment of the invention, a modal testing method for simulating gas pulsation excitation in an automotive intake system includes the following key technologies: First, the design of an electromagnetic excitation device 2, which uses an array of ring-shaped electromagnetic coils 12 to generate an axial pulsating magnetic field through alternating current, driving a magnetic piston 11 to produce controllable pressure fluctuations; second, pulsation parameter matching, establishing a mapping relationship between the pulsation frequency and the electromagnetic excitation signal based on engine speed to achieve a 20-200Hz wideband excitation; third, the connection of a data acquisition system 6, which integrates a DSP controller and establishes an electrical connection with a power amplifier 5 through its internal circuitry, outputting the original excitation signal to the power amplifier 5; simultaneously, the DSP controller establishes a timing synchronization control relationship with the sensor acquisition link through the signal interface of the data acquisition system 6. The data acquisition system 6 is also electrically connected to an analysis system 7, using the power amplifier 5 to adjust the operating current of the electromagnetic coils 12, controlling the pulsation amplitude, and simulating the gas pulsation intensity under different operating conditions.

[0027] like Figure 3 As shown, in this embodiment of the invention, the electromagnetic excitation device 2 includes a plurality of electromagnetic coils 12 arranged circumferentially along the intake pipe 9, and the plurality of electromagnetic coils 12 constitute an electromagnetic excitation array surrounding the intake pipe 9.

[0028] In this embodiment of the invention, an electromagnetic excitation array is disposed in the throat region of the intake pipe 9 and is installed on the outside of the intake pipe 9 by a fixed structure, so that the electromagnetic excitation acts on the intake channel position corresponding to the throat region. The electromagnetic excitation device 2 consists of multiple annular electromagnetic coils 12 arranged in a certain manner and installed at the throat position of the intake pipe 9. These coils are usually closely arranged to form an array structure surrounding the pipe. The throat position of the intake pipe 9 refers to the pipe section with the smallest cross-sectional area, such as the throttle valve installation position. The gas flow velocity is the highest at this position, and the transmission and response characteristics of gas pressure fluctuations are the most significant. Therefore, in the modal testing of the intake system, choosing to place the excitation device here can more efficiently simulate the intake gas pulsation under real working conditions.

[0029] In this embodiment of the invention, the ring array should contain a sufficient number of electromagnetic coils 12, such as 8-12 electromagnetic coils 12, to form a continuous excitation field.

[0030] like Figure 3As shown, in this embodiment of the invention, the fixing structure includes a clamp 13, which fixes the electromagnetic coil 12 at the throat position of the intake pipe 9. The clamp 13 can be manufactured according to the shape and size of the pipe to ensure a tight fit. The clamp 13 can be adjusted in tightness to adapt to pipes of different sizes or to be disassembled and installed as needed. Multiple electromagnetic coils 12 are connected to independent control channels to adjust the excitation phase and amplitude of each electromagnetic coil 12. Each electromagnetic coil 12 in the ring electromagnetic coil 12 array is electrically connected to an independent control channel, allowing independent control of the excitation phase and amplitude of the corresponding electromagnetic coil 12. Specifically, each electromagnetic coil 12 can dynamically adjust its output pulsation parameters in real time according to test requirements, thereby adapting to different operating conditions of the intake system, ensuring effective coverage of the excitation signal on the intake pipe 9, and ensuring that the excitation effect matches the gas pulsation characteristics under real operating conditions. Figure 1 As shown, each electromagnetic coil 12 is electrically connected to the power amplifier 5, and the power amplifier 5 is further electrically connected to the data acquisition system 6. Through the above connection, the data acquisition system 6 can output a control signal to the power amplifier 5, which then adjusts the drive current of each electromagnetic coil 12 according to the control signal, thereby controlling the excitation parameters of each electromagnetic coil 12 and ensuring the stability and controllability of the excitation signal.

[0031] like Figure 3 As shown, in this embodiment of the invention, the movable component is a magnetic piston 11 disposed within the intake channel. The magnetic piston 11 reciprocates axially along the intake channel under the influence of an electromagnetic field, thereby generating pressure pulsations. The intake channel is a gas flow channel formed inside the intake pipe 9. In step S2 above, a drive signal is output to each electromagnetic coil 12 via a DSP controller, causing each electromagnetic coil 12 to collaboratively generate an axially pulsating magnetic field. Under the influence of the axially pulsating magnetic field, the magnetic piston 11 within the intake channel performs periodic axial reciprocating motion, thereby generating periodic pressure fluctuations within the intake channel, thus reproducing the gas pulsation effect generated during the opening and closing of the engine intake valve.

[0032] In step S2 above, a stepped adjustment mechanism for the pulse frequency is set, with a frequency step value that can be set to 10Hz, and the test range of the excitation frequency covering 20Hz~200Hz. This stepped frequency adjustment method enables excitation testing of the intake system under all operating conditions, ensuring the integrity of the test data. The stepped adjustment mechanism for the pulse frequency is preset and executed by the DSP controller integrated into the data acquisition system 6. The specific settings and operation process are as follows: I. The preset configuration of the step-by-step adjustment parameters is as follows: In the DSP controller's control program, a set of adjustment parameters for the pulse frequency is pre-configured: 1. Excitation frequency range: The starting value of the excitation frequency is set to 20Hz and the ending value is 200Hz. This range corresponds to the intake gas pulsation frequency range under engine idling to high-speed operation conditions, which can cover the dynamic response scenarios of the intake system under all operating conditions. 2. Frequency step value: Set the frequency step value to 10Hz, and generate a complete frequency adjustment sequence based on this step value (e.g., set 19 discrete frequency points: 20Hz, 30Hz, 40Hz, ..., 200Hz). 3. Steady-state duration at a single frequency point: Preset the duration of steady-state excitation at each frequency point (e.g., 5s) to ensure that the intake system generates stable vibration and pressure response under the excitation at that frequency.

[0033] II. The execution process of step-by-step adjustment is as follows: The DSP controller automatically performs stepped frequency adjustment according to a preset parameter set: 1. Frequency sequence traversal: The DSP controller calls the excitation signal generation module sequentially according to the frequency adjustment sequence described above to generate the original excitation signal corresponding to the target frequency; 2. Excitation signal transmission: The original excitation signal corresponding to each target frequency is transmitted to the power amplifier 5. After power amplification, it drives the electromagnetic coil 12, causing the electromagnetic coil 12 to generate pressure pulsation at the corresponding frequency. 3. Single-frequency point test: At each target frequency, the DSP controller controls the electromagnetic coil 12 to maintain steady-state excitation at that frequency, and synchronously triggers the data acquisition system 6, so that the vibration response sensor 3 and the pressure sensor 4 can collect the response data during the steady-state excitation period. 4. Cyclic Switching: After completing the test at the current frequency point, the DSP controller automatically switches to the next step frequency and repeats the above process of excitation generation, signal amplification, and data acquisition until all frequency points in the range of 20Hz to 200Hz are traversed.

[0034] In step S3 above, data acquisition is performed synchronously. At the same time as the electromagnetic excitation is started, the data acquisition actions of the vibration response sensor 3 and the pressure sensor 4 are triggered simultaneously, so that the acquisition sequence of the two types of sensors is strictly aligned to avoid phase deviation of the acquired data, thereby ensuring the time correlation between structural vibration data and pressure fluctuation data.

[0035] like Figure 3 As shown in this embodiment of the invention, the correspondence between the excitation frequency and the engine speed is established through a lookup table or a function mapping method. The frequency range of the pulsating excitation covers 20Hz to 200Hz, and scanning tests are performed by setting a frequency stepping method.

[0036] Beforehand, engine bench tests are conducted to collect the actual gas pulsation frequency of the target vehicle's engine in the intake manifold 9 at different engine speeds. The corresponding data sets of engine speed values ​​and actual intake pulsation frequency values ​​are organized into a pre-stored mapping table, which is then written into the storage unit of the DSP controller. For example, for a four-stroke single-cylinder engine, bench tests show that when the engine speed is 2000 rpm, the actual gas pulsation frequency in the intake manifold 9 is 33.3 Hz. The corresponding entry for 2000 rpm → 33.3 Hz is then recorded in the mapping table. Similarly, speed-frequency data under idling, high-speed, and other operating conditions can be acquired and stored to form a mapping table covering all operating conditions.

[0037] The DSP controller calls a pre-stored mapping table to generate a square wave excitation signal of the corresponding frequency based on the input engine speed. This square wave signal is transmitted to the power amplifier 5, which amplifies the signal and then outputs a matching drive current to the electromagnetic coil 12. By adjusting the output current amplitude of the power amplifier 5, the intensity of the pulsating magnetic field generated by the electromagnetic coil 12 can be controlled, thereby regulating the reciprocating motion amplitude of the magnetic piston 11, ultimately simulating the intensity of gas pulsation in the intake pipe 9 under different operating conditions.

[0038] like Figure 1 As shown, in this embodiment of the invention, a vibration response sensor 3 and a pressure sensor 4 are arranged at key locations in the intake system. The vibration response sensor 3 is arranged on the surface of the air filter 10 and the resonant cavity 8, with a sampling frequency of not less than 500Hz to capture high-frequency vibration signals; at the same time, the pressure sensor 4 is installed on the surface of the intake pipe 9 to synchronously monitor the pulsating pressure changes.

[0039] In this embodiment of the invention, the vibration response sensor 3 is an acceleration sensor, which is arranged on the outer surface of the air filter 10 and the resonant cavity 8 of the intake system. By placing the acceleration sensor at the above-mentioned key structural locations, the vibration response signal of the intake system under pulsating excitation can be accurately collected, providing reliable data support for subsequent modal parameter identification.

[0040] In another embodiment of the present invention, the vibration response sensor 3 may also be a non-contact sound pressure sensor. When a non-contact sound pressure sensor is used, the vibration signal of the intake system can be collected in a non-contact manner, and the vibration response characteristics can be indirectly obtained. This setting can adapt to some test scenarios where it is inconvenient to deploy contact sensors, thereby improving the applicability of this test method.

[0041] In embodiments of the present invention, such as Figure 1As shown, the vibration response sensor 3 and the pressure sensor 4 are electrically connected to the data acquisition system 6. The vibration signal and the pressure signal are synchronously acquired through the same data acquisition system 6 and time-aligned based on a unified time reference. The acquired data is processed in the time domain and frequency domain to obtain the frequency response function. Modal parameter identification includes identifying the modal frequencies based on the frequency domain decomposition method and reconstructing the corresponding mode shapes.

[0042] In step S4 above, after data acquisition is completed, the analysis system 7 performs time-domain and frequency-domain transformation on the acquired vibration and pressure data to extract the frequency response function. The frequency domain decomposition (FDD) algorithm is used to identify resonance peaks and modal frequencies, and the inherent characteristics of the system are determined through pole estimation and mode shape reconstruction.

[0043] The present invention has been described above by way of example with reference to the accompanying drawings. Obviously, the specific implementation of the present invention is not limited to the above-described manner. Any non-substantial improvements made using the inventive concept and technical solution of the present invention, or the direct application of the inventive concept and technical solution of the present invention to other occasions without modification, are all within the protection scope of the present invention.

Claims

1. A modal testing method for an automotive intake system, characterized in that, Including the following steps: S1: An electromagnetic excitation device is installed at the intake pipe position of the automobile intake system. The electromagnetic excitation device generates a periodically changing electromagnetic field to drive the movable parts that cooperate with the intake channel to form pressure pulsation, thereby applying simulated gas pulsation excitation to the intake system. S2: Based on the engine speed, establish the correspondence between the excitation frequency of the pressure pulsation and the electromagnetic excitation signal, and generate the electromagnetic excitation signal according to the correspondence to achieve pulsation excitation in different frequency ranges; S3: By arranging vibration response sensors and pressure sensors at at least two structural locations in the intake system, vibration signals and pressure signals of the intake system under the pulsating excitation are collected respectively. S4: Process the collected vibration and pressure signals to extract the frequency response information of the intake system, and perform modal parameter identification based on the frequency response information to obtain the modal characteristics of the intake system.

2. The modal testing method for an automotive intake system according to claim 1, characterized in that, The electromagnetic excitation device includes multiple electromagnetic coils arranged circumferentially along the intake pipe, and the multiple electromagnetic coils constitute an electromagnetic excitation array surrounding the intake pipe.

3. The modal testing method for an automotive intake system according to claim 2, characterized in that, The electromagnetic excitation array is disposed in the throat region of the intake duct and is installed on the outside of the intake duct by a fixed structure so that the electromagnetic excitation acts on the intake channel position corresponding to the throat region.

4. The modal testing method for an automotive intake system according to claim 2, characterized in that, The plurality of electromagnetic coils are each connected to an independent control channel to adjust the excitation phase and excitation amplitude of each electromagnetic coil.

5. The modal testing method for an automotive intake system according to any one of claims 1 to 4, characterized in that, The movable component is a magnetic piston disposed in the air intake channel. The magnetic piston reciprocates along the axial direction of the air intake channel under the action of an electromagnetic field to form the pressure pulsation.

6. The modal testing method for an automotive intake system according to any one of claims 1 to 4, characterized in that, The relationship between the excitation frequency and the engine speed is established by a lookup table or a function mapping method.

7. The modal testing method for an automotive intake system according to any one of claims 1 to 4, characterized in that, The frequency range of the pulsed excitation covers 20Hz to 200Hz, and scanning tests are performed by setting a frequency step mode.

8. The modal testing method for an automotive intake system according to any one of claims 1 to 4, characterized in that, The vibration response sensor is an acceleration sensor, which is arranged on the outer surface of the air filter and / or resonant cavity of the intake system.

9. The modal testing method for an automotive intake system according to any one of claims 1 to 4, characterized in that, The vibration response sensor is a non-contact sound pressure sensor.

10. The modal testing method for an automotive intake system according to any one of claims 1 to 4, characterized in that, The vibration and pressure signals are synchronously acquired through the same data acquisition system and time-aligned based on a unified time reference. The collected data is processed in the time domain and frequency domain to obtain the frequency response function; The modal parameter identification includes identifying modal frequencies based on a frequency domain decomposition method and reconstructing the corresponding mode shapes.

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