A method for analyzing the contribution of exhaust suspension vibration isolation elements to vehicle interior noise

Abstract

A method for analyzing the contribution of exhaust suspension vibration isolation elements to vehicle interior noise, the method comprising the following steps: based on the high-frequency usage scenarios of the test vehicle, selecting an idle condition and an acceleration condition as the test conditions of the test vehicle; after the body side suspension and the exhaust suspension of the test vehicle are connected in an elastic connection manner, starting to perform an idle condition test and an acceleration condition test on the test vehicle to obtain the peak values ​​of the main-order noise curves; after the body side suspension and the exhaust suspension of the test vehicle are connected in a rigid connection manner, starting to perform an idle condition test and an acceleration condition test on the test vehicle to obtain the peak values ​​of the main-order noise curves; comparing the peak values ​​of the main-order noise curves obtained in the above idle condition tests, comparing the peak values ​​of the main-order noise curves obtained in the above acceleration condition tests, and calculating the main-order noise contribution ratio of the idle condition test and the acceleration condition test.

Description

Technical Field

[0001] The present invention relates to the field of in-vehicle NVH technology, and in particular to a method for analyzing the contribution of an exhaust suspension vibration isolation element to in-vehicle noise. Background Art

[0002] With the development of the automotive industry, users have higher and higher requirements for the NVH performance of automobiles. According to JDPQWER statistics, user complaints about NVH account for about 1 / 4 of the total complaints. The driving noise in the car is a direct impact on the user's driving perception. In order to effectively improve the quietness in the car, NVH engineers isolate and verify various noise sources, accurately obtain the contribution of the excitation source and the transmission path, and formulate effective solutions for the factors with large contributions to improve the auditory perception of customers in the car.

[0003] The power system excitation is an important component of the noise inside the car, mainly including the engine excitation, intake system excitation, exhaust system excitation, etc., mainly the main order and harmonious order of the engine, and the frequency is concentrated within 500Hz. The exhaust system is affected by the vibration of the engine itself and the exhaust airflow excitation, and the exhaust pipe vibration is very obvious. This excitation is transmitted to the body floor through the exhaust suspension vibration isolation system, causing the vibration of the body floor and other body sheet metal to radiate noise, causing auditory perception by customers in the car. The analysis of the contribution of in-car noise usually adopts the isolation method, that is, isolating or removing the transmission of this part of the excitation to confirm the change of in-car noise. The isolation method can evaluate the contribution of the entire transmission path to the noise inside the car, but the isolation method cannot isolate the contribution of the vibration isolation system alone.

[0004] Prior art, patent document CN103362598B discloses "a method for separating noise sources outside an accelerating vehicle", measures the noise outside an accelerating vehicle under different working conditions, and obtains the first to fifth noise sound pressure levels; secondly, calculates the tire noise sound pressure level, the powertrain mechanical noise sound pressure level, the powertrain combustion noise sound pressure level, the exhaust muffler shell noise sound pressure level and the exhaust port noise sound pressure level; then calculates the tire noise energy contribution ratio, the powertrain mechanical noise energy contribution ratio, the powertrain combustion noise energy contribution ratio, the exhaust muffler shell noise energy contribution ratio and the exhaust port noise energy contribution ratio, thereby achieving the separation of the five noise sources outside the accelerating vehicle, accurately distinguishing the composition of the noise source, so as to accurately select the noise reduction means to be used and improve the noise reduction effect.

[0005] In summary, existing isolation methods cannot isolate the contribution of the vibration isolation system. Summary of the invention

[0006] The present invention solves the problem that the existing isolation method cannot isolate the contribution to the vibration isolation system separately.

[0007] The method for analyzing the contribution of an exhaust suspension vibration isolation element to vehicle interior noise according to the present invention comprises the following steps:

[0008] Step S1, based on the high-frequency usage scenarios of the vehicle to be tested, selecting an idle condition and an acceleration condition as the test conditions of the vehicle to be tested;

[0009] Step S2, after the body side suspension and the exhaust suspension of the test vehicle are connected by elastic connection, the idling condition test and the acceleration condition test of the test vehicle are started to obtain the peak value of the noise curve of the main order;

[0010] Step S3, after the vehicle body side suspension and the exhaust suspension of the test vehicle are connected in a rigid connection manner, an idling condition test and an acceleration condition test are started on the test vehicle to obtain the peak values ​​of the noise curves of the main orders;

[0011] Step S4, compare the peak values ​​of the main order noise curves obtained from the idle condition tests of step S2 and step S3, compare the peak values ​​of the main order noise curves obtained from the acceleration condition tests of step S2 and step S3, and calculate the main order noise contribution ratio of the idle condition test and the acceleration condition test.

[0012] Further, in one embodiment of the present invention, the main orders include 2nd order, 4th order, 6th order, 8th order and 10th order.

[0013] Further, in one embodiment of the present invention, the process of starting the idle condition test on the vehicle to be tested is as follows:

[0014] The vehicle to be tested is placed in an anechoic chamber environment. The vehicle to be tested is fully preheated before the test. During the test, the cooling fan and electrical load equipment are ensured to be in the off state. The noise signals of the front and rear rows of the vehicle to be tested are collected when the engine is in the hot state.

[0015] Further, in one embodiment of the present invention, the step of starting to perform an acceleration condition test on the vehicle to be tested is specifically as follows:

[0016] The test vehicle was fully preheated before the test. During the test, the vehicle was driven at the lowest stable engine speed in 3rd gear, and then accelerated to the rated speed at full throttle to collect the noise signals from the front and rear rows of the vehicle.

[0017] Further, in one embodiment of the present invention, the vehicle to be tested is fully preheated before the test by:

[0018] The engine coolant temperature reaches 85±5℃ or the vehicle to be tested travels more than 15km.

[0019] Furthermore, in one embodiment of the present invention, the idle condition test and the acceleration condition test are both repeated at least three times.

[0020] Further, in one embodiment of the present invention, in step S3, the rigid connection method is:

[0021] The hook is made of iron wire, and the connection size of the hook in the Z direction is the same as the elastic connection method.

[0022] Furthermore, in an embodiment of the present invention, in the step S4, the noise contribution ratio is calculated using sound energy.

[0023] Further, in one embodiment of the present invention, in the step S4, the formula for the main order noise contribution ratio of the idle condition test is:

[0024] In the formula, A i is the peak value of the main order noise curve obtained by the elastic connection idle condition test, X2 is the peak value of the main order noise curve obtained by the elastic connection idle condition test, α i is the main order noise contribution ratio.

[0025] Further, in one embodiment of the present invention, in the step S4, the formula for the main order noise contribution ratio of the acceleration condition test is:

[0026] In the formula, B j is the peak value of the main order noise curve obtained from the idling condition test of the elastic connection method, Y j is the peak value of the main order noise curve obtained from the idling condition test of the elastic connection method, β j is the main order noise contribution ratio.

[0027] The present invention solves the problem that the existing isolation method cannot isolate the contribution of the vibration isolation system. Specific beneficial effects include:

[0028] The present invention provides a method for analyzing the contribution of exhaust suspension vibration isolation elements to in-vehicle noise. According to the high-frequency use scenarios of users, a new vibration isolation system contribution analysis method is provided by using a rigid connection between the exhaust suspension and the vehicle body floor instead of an elastic connection. Idle speed and acceleration are selected as verification conditions for the analysis of the contribution of exhaust suspension vibration isolation performance. Two verification states are designed: ① The exhaust suspension and the vehicle body floor are connected by elastic rubber hanging ears (mass production state); ② The exhaust suspension and the vehicle body floor are rigidly connected. By comparing the changes in in-vehicle noise under the two states, the proportion of energy absorbed by the exhaust vibration isolation system can be calculated using the principle of sound energy superposition, that is, the contribution of the exhaust suspension vibration isolation system under each working condition is obtained. The verification results provide a basis for optimizing the structure and stiffness of the exhaust rubber hanging ears, and at the same time have guiding significance for the forward development and design of the exhaust suspension vibration isolation system. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0030] Figure 1 It is a flow chart of a method for analyzing the contribution of exhaust suspension vibration isolation elements to vehicle interior noise according to a specific implementation method.

[0031] Figure 2 It is a structural diagram of the exhaust rubber hanging ear described in a specific implementation method.

[0032] Figure 3 It is a diagram of the exhaust suspension connection structure described in a specific implementation method. DETAILED DESCRIPTION

[0033] The following will clearly and completely describe various embodiments of the present invention in conjunction with the accompanying drawings. The embodiments described with reference to the accompanying drawings are exemplary and intended to be used to explain the present invention, but should not be understood as limiting the present invention.

[0034] The method for analyzing the contribution of exhaust suspension vibration isolation elements to vehicle interior noise described in this embodiment includes the following steps:

[0035] Step S1, based on the high-frequency usage scenarios of the vehicle to be tested, selecting an idle condition and an acceleration condition as the test conditions of the vehicle to be tested;

[0036] Step S2, after the body side suspension and the exhaust suspension of the test vehicle are connected by elastic connection, the idling condition test and the acceleration condition test of the test vehicle are started to obtain the peak value of the noise curve of the main order;

[0037] Step S3, after the vehicle body side suspension and the exhaust suspension of the test vehicle are connected in a rigid connection manner, an idling condition test and an acceleration condition test are started on the test vehicle to obtain the peak values ​​of the noise curves of the main orders;

[0038] Step S4, compare the peak values ​​of the main order noise curves obtained from the idle condition tests of step S2 and step S3, compare the peak values ​​of the main order noise curves obtained from the acceleration condition tests of step S2 and step S3, and calculate the main order noise contribution ratio of the idle condition test and the acceleration condition test.

[0039] In this implementation manner, the main orders include 2nd order, 4th order, 6th order, 8th order and 10th order.

[0040] In this embodiment, the idling condition test of the vehicle to be tested is started as follows:

[0041] The vehicle to be tested is placed in an anechoic chamber environment. The vehicle to be tested is fully preheated before the test. During the test, the cooling fan and electrical load equipment are ensured to be in the off state. The noise signals of the front and rear rows of the vehicle to be tested are collected when the engine is in the hot state.

[0042] In this embodiment, the acceleration condition test of the vehicle to be tested is started as follows:

[0043] The test vehicle was fully preheated before the test. During the test, the vehicle was driven at the lowest stable engine speed in 3rd gear, and then accelerated to the rated speed at full throttle to collect the noise signals from the front and rear rows of the vehicle.

[0044] In this embodiment, the method of fully preheating the vehicle to be tested before the test is as follows:

[0045] The engine coolant temperature reaches 85±5℃ or the vehicle to be tested travels more than 15km.

[0046] In this embodiment, the idle condition test and the acceleration condition test are both repeated at least 3 times.

[0047] In this embodiment, in step S3, the rigid connection method is:

[0048] The hook is made of iron wire, and the connection size of the hook in the Z direction is the same as the elastic connection method.

[0049] In this implementation manner, in the step S4, the noise contribution ratio is calculated using sound energy.

[0050] In this implementation manner, in the step S4, the formula for the main order noise contribution ratio of the idle condition test is:

[0051] In the formula, A i is the peak value of the main order noise curve obtained by the elastic connection idle condition test, X2 is the peak value of the main order noise curve obtained by the elastic connection idle condition test, α i is the main order noise contribution ratio.

[0052] In this embodiment, in step S4, the formula for the main order noise contribution ratio of the acceleration condition test is:

[0053] In the formula, B j is the peak value of the main order noise curve obtained from the idling condition test of the elastic connection method, Y j is the peak value of the main order noise curve obtained from the idling condition test of the elastic connection method, β j is the main order noise contribution ratio.

[0054] This embodiment is based on the method for analyzing the contribution of the exhaust suspension vibration isolation element to the vehicle interior noise according to the present invention, combined with Figure 1 This embodiment can be better understood, and a practical embodiment is provided in combination with specific objects:

[0055] By comparing the rigid connection mode between the exhaust system and the vehicle body floor with the elastic connection mode (in mass production), the change of the noise energy inside the vehicle is verified, and the contribution of the structure-transmitted noise of a certain exhaust suspension vibration isolation system is obtained. There are four steps in total:

[0056] Step 1: Select test conditions based on user scenarios

[0057] Based on the high-frequency usage scenarios of users, fixed and dynamic driving scenarios are selected as verification conditions. In the idle condition, due to the low background noise (no wind noise and road noise excitation), the main-order low-frequency noise in the car is very easy to cause the user's auditory perception, so the idle P gear is selected as the fixed typical scenario; in the acceleration condition, the powertrain excitation is large, and the 3rd gear full throttle acceleration can cover the full engine speed range, so the 3rd gear full throttle acceleration is selected as the dynamic typical scenario.

[0058] Step 2: Initial state in-vehicle noise test analysis

[0059] The exhaust suspension of the test vehicle is installed and matched according to the design state (elastic vibration isolation element), and the in-vehicle noise signal is tested under the selected test conditions. Since the exhaust system is mainly excited by the 2nd, 4th, 6th, 8th and 10th order of the engine, the focus is on analyzing the noise contribution of the main orders.

[0060] Idle P gear test analysis: The vehicle is placed in an anechoic chamber environment. Before the test, the vehicle is fully preheated to make the engine coolant temperature reach the temperature of the vehicle during normal driving (85±5)℃ or driving for more than 15km; during the test, ensure that the cooling fan and electrical load equipment (low beam, fog lamp, rearview mirror heating, etc.) are turned off, and collect the front and rear row noise signals in the hot engine state. Analyze the noise signal spectrum in the car to obtain the engine 2nd, 4th, 6th, 8th, and 10th order noise peaks A2, A4, A6, A8, A 10 .

[0061] Acceleration condition test analysis: The road test is conducted using 3rd gear full throttle acceleration. The test environment meets the test standard requirements. The vehicle must be preheated before the test so that the engine coolant temperature reaches the temperature of the vehicle during normal driving (85±5)°C or it has been driven for more than 15km. During the test, the engine is driven at the lowest stable speed in 3rd gear, and then it is accelerated to the rated speed at full throttle. The noise signals from the front and rear rows in the vehicle are collected during this process. The same condition is repeated at least 3 times. The curves of the changes in the 2nd, 4th, 6th, 8th, and 10th order noise of the engine in the vehicle with the engine speed under this condition are processed and analyzed. The acceleration condition mainly analyzes the peak values ​​caused by resonance in certain speed ranges, and obtains the peak values ​​of the noise curves of each order, B2, B4, B6, B8, B9, B10, B11, B12, B13, B14, B15, B16, B17, B18, B19, B20, B21, B22, B23, B24, B25, B26, B27, B28, B29, B30, B31, B32, B33, B34, B35, B36, B37, B38, B39, B40, B41, B42, B43, B44, B45 10 .

[0062] Step 3: Design and test analysis of the exhaust suspension rigid connection scheme

[0063] In order to reduce the transmission of exhaust pipe vibration energy to the vehicle body floor, the exhaust side suspension is usually elastically connected to the vehicle body side suspension through a rubber lug, which plays a vibration isolation role. In order to obtain the contribution of the exhaust structure transfer path, the structural path isolation method is usually used, that is, the exhaust lug is removed and the connection between the exhaust system and the vehicle body floor is disconnected. However, after removing a certain suspension, the stress state of other suspensions will change, and it is impossible to accurately obtain the contribution of a certain suspension vibration isolation system.

[0064] like Figure 2-3 As shown, in order to accurately obtain the contribution of a certain suspension vibration isolation system, a hook made of iron wire (a rigid structure with the same size as the rubber ear can also be trial-made) is used instead of the rubber ear to rigidly connect the body side suspension A and the exhaust suspension B, and the connection size of the hook in the Z direction is the same as the rubber ear. This can ensure that after a certain suspension is replaced with an iron hook, the stress state of other suspensions remains unchanged. In this way, the vibration of the exhaust system is transmitted to the body floor through the rigid connection structure without being attenuated by the vibration isolation system.

[0065] For the test vehicle with the exhaust suspension rigidly connected, the idle P gear and 3rd gear full throttle acceleration tests were carried out. The test operation process was the same as the second step. The 2nd, 4th, 6th, 8th and 10th order interior noise peak values ​​X2, X4, X6, X8, X10 The peak values ​​of the 2nd, 4th, 6th, 8th and 10th order noise curves Y2, Y4, Y6, Y8, Y 10 .

[0066] Step 4: Analysis and application of exhaust suspension vibration isolation component contribution

[0067] By comparing the changes in the peak noise level inside the vehicle under the initial state of the exhaust suspension (elastic connection) and the state of the exhaust suspension rigidly connected, the noise contribution analysis is calculated using sound energy. According to the principle of sound energy superposition, the difference in sound energy between the two is the noise energy isolated by the vibration isolation element, which is the contribution of the vibration isolation element.

[0068] Idle condition contribution analysis: Sound energy is calculated based on the relationship between sound pressure level and sound energy According to the sound energy superposition method, the engine second-order noise contribution ratio can be calculated The same method is used to calculate the 4th, 6th, 8th, and 10th order noise contribution ratios, respectively.

[0069] Analysis of the contribution of acceleration conditions: Based on the results of the two exhaust suspension states of 3rd gear full throttle acceleration, the change in the peak value of the curve is mainly analyzed. The same calculation method is used to obtain the 2nd order noise contribution ratio, 4th order noise contribution ratio, 6th order noise contribution ratio, 8th order noise contribution ratio, and 10th order noise contribution ratio of the exhaust suspension vibration isolation element under acceleration conditions, respectively.

[0070] For the speed range where the noise peak is significantly improved, the suspension vibration isolation optimization path needs to be considered when optimizing the problem, especially when the exhaust suspension elastic element is forward designed, the suspension vibration isolation rate requirement needs to be increased to ensure sufficient vibration isolation capability to attenuate the transmission of exhaust vibration to the vehicle body floor.

[0071] The above is a detailed introduction to the method for analyzing the contribution of an exhaust suspension vibration isolation element to the interior noise of a vehicle proposed in the present invention. Specific examples are used in this article to illustrate the principle and implementation method of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation method and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A method for analyzing the contribution of exhaust suspension vibration isolation elements to vehicle interior noise, characterized in that: The following steps are involved: Step S1, based on the high-frequency usage scenarios of the vehicle to be tested, selecting an idle condition and an acceleration condition as the test conditions of the vehicle to be tested; Step S2, after the body side suspension and the exhaust suspension of the test vehicle are connected by elastic connection, the idling condition test and the acceleration condition test of the test vehicle are started to obtain the peak value of the noise curve of the main order; Step S3, after the vehicle body side suspension and the exhaust suspension of the test vehicle are connected in a rigid connection manner, an idling condition test and an acceleration condition test are started on the test vehicle to obtain the peak values ​​of the noise curves of the main orders; Step S4, comparing the peak values ​​of the main order noise curves obtained in the idle condition test of step S2 and step S3, comparing the peak values ​​of the main order noise curves obtained in the acceleration condition test of step S2 and step S3, and calculating the main order noise contribution ratio of the idle condition test and the acceleration condition test; In the step S4, the formula for the main order noise contribution ratio of the idle condition test is: In the formula, A i is the peak value of the main order noise curve obtained from the idling condition test of the elastic connection mode, X i is the main order interior noise peak of the engine at idle P gear with rigid connection, α i is the main order noise contribution ratio; In the step S4, the formula for the main order noise contribution ratio of the acceleration condition test is: In the formula, B j is the peak value of the main order noise curve obtained from the accelerated working condition test of the elastic connection method, Y j is the peak value of the main order noise curve of the engine under the third gear full throttle acceleration condition with rigid connection, β j is the main order noise contribution ratio.

2. The method for analyzing the contribution of exhaust suspension vibration isolation elements to vehicle interior noise according to claim 1, characterized in that: The main orders include 2nd, 4th, 6th, 8th and 10th orders.

3. The method for analyzing the contribution of exhaust suspension vibration isolation elements to vehicle interior noise according to claim 1, characterized in that: The above-mentioned starting of the idle speed test of the vehicle to be tested is specifically as follows: The vehicle to be tested is placed in an anechoic chamber environment. The vehicle to be tested is fully preheated before the test. During the test, the cooling fan and electrical load equipment are ensured to be in the off state. The noise signals of the front and rear rows of the vehicle to be tested are collected when the engine is in the hot state.

4. The method for analyzing the contribution of exhaust suspension vibration isolation elements to vehicle interior noise according to claim 1, characterized in that: The acceleration condition test of the vehicle to be tested is started as follows: The test vehicle was fully preheated before the test. During the test, the vehicle was driven at the lowest stable engine speed in 3rd gear, and then accelerated to the rated speed at full throttle to collect the noise signals from the front and rear rows of the vehicle.

5. A method for analyzing the contribution of exhaust suspension vibration isolation elements to vehicle interior noise according to claim 3 or 4, characterized in that: The method of fully preheating the vehicle to be tested before the test is as follows: The engine coolant temperature reaches 85±5℃ or the vehicle to be tested travels more than 15km.

6. The method for analyzing the contribution of exhaust suspension vibration isolation elements to vehicle interior noise according to claim 1, characterized in that: The idle condition test and the acceleration condition test are repeated at least 3 times.

7. The method for analyzing the contribution of exhaust suspension vibration isolation elements to vehicle interior noise according to claim 1, characterized in that: In the step S3, the rigid connection method is: The hook is made of iron wire, and the connection size of the hook in the Z direction is the same as the elastic connection method.

8. The method for analyzing the contribution of exhaust suspension vibration isolation elements to vehicle interior noise according to claim 1, characterized in that: In the step S4, the noise contribution ratio is calculated using sound energy.

Images