Abnormal Sound Analysis Method

Abstract

This invention provides a noise analysis method that can determine abnormal noises caused by deterioration of the mounting rubber. [Solution] The abnormal noise analysis method involves detecting the frequency of abnormal noises generated from a vehicle, estimating the degree of deterioration of the mount rubber supporting the internal structure of the vehicle based on the vehicle's usage conditions, and determining that the mount rubber is the cause of the abnormal noise if the difference between the resonant frequency of the mount rubber corresponding to the degree of deterioration and the frequency of the abnormal noise is below a threshold.

Description

Technical Field

[0001] The present invention relates to a method for analyzing abnormal noises.

Background Art

[0002] Regarding a method for analyzing abnormal noises, for example, Patent Document 1 describes identifying a sound source that generates a sound as the rotation device such as an engine rotates.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, the causes of abnormal noises in a vehicle include not only a rotating device such as an engine but also deterioration of mount rubber that supports the engine or the like, which may also be a cause of abnormal noises.

[0005] Therefore, the present invention has been made in view of the above problems, and an object thereof is to provide a method for analyzing abnormal noises that can determine abnormal noises caused by deterioration of mount rubber.

Means for Solving the Problems

[0006] The method for analyzing abnormal noises of the present invention detects the frequency of an abnormal noise generated from a vehicle, estimates the degree of deterioration of mount rubber that supports a structure in the vehicle from the usage state of the vehicle, and when the difference between the resonance frequency of the mount rubber corresponding to the degree of deterioration and the frequency of the abnormal noise is not more than a threshold value, determines that the mount rubber is the cause of the abnormal noise.

Effects of the Invention

[0007] According to the present invention, it is possible to determine an abnormal noise caused by deterioration of mount rubber. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a diagram showing an example of a system for analyzing abnormal sounds. [Figure 2] Figure 2 is a flowchart showing an example of abnormal sound analysis processing. [Figure 3] Figure 3 shows an example of the characteristics of sound pressure change. [Modes for carrying out the invention]

[0009] (Configuration of the abnormal noise detection system) Figure 1 is a configuration diagram showing an example of an abnormal noise analysis system S. The abnormal noise analysis system S includes a terminal 1 such as a tablet or personal computer, and an abnormal noise analysis server 2. The abnormal noise analysis system S is installed, for example, in a service center for a vehicle V such as a hybrid vehicle or an electric vehicle, and analyzes abnormal noises generated from the vehicle V in response to user requests.

[0010] Vehicle V is equipped with, for example, an engine 3 as a drive source. A set of mounts 30 are attached to the engine 3, and elastic mount rubber 31 is provided between the mounts 30 and the vehicle body 32. The mount rubber 31 supports the engine 3, but if its elasticity decreases and it hardens due to aging or other deterioration, it may become a source of abnormal noise. Note that the engine 3 is an example of a structure supported by the mount rubber 31, but the structure is not limited to this and may be a motor, transaxle, etc.

[0011] Vehicle V is also equipped with a storage device 40 such as memory, and a communication module 41 that can access a communication network such as the Internet. The storage device 40 stores information about the vehicle's usage status, such as the mileage and area of ​​use, and information about the driving status, such as the rotational speed of the engine 3 (hereinafter referred to as vehicle information). The communication module 41 transmits the vehicle information stored in the storage device 40 to terminal 1 in response to a request from terminal 1.

[0012] Terminal 1 is an example of a computer and includes a CPU (Central Processing Unit) 10, memory 11 such as ROM (Read Only Memory) and RAM (Random Access Memory), and a microphone 12. The CPU 10 executes a series of processes in a predetermined sequence according to a program stored in memory 11.

[0013] The microphone 12 acquires sound generated from the vehicle V and outputs it to the CPU 10. As described later, the CPU 10 analyzes the sound to determine whether or not there is an abnormal noise caused by deterioration of the mount rubber 31.

[0014] The abnormal sound analysis server 2 stores the ambient temperature database (DB) 20 and the hardness-resonance frequency DB 21, which are used for abnormal sound analysis processing, in memory (not shown). During abnormal sound analysis, terminal 1 accesses the ambient temperature DB 20 and the hardness-resonance frequency DB 21 via the communication network.

[0015] The Ambient Temperature DB20 contains data on the ambient temperature of the powertrain, such as engine 3, for each vehicle V manufacturing number. The Hardness-Resonance Frequency DB21 contains data showing the correlation between the hardness Hs (HS) of the mount rubber 31 and the resonance frequency fo (Hz) for each vehicle V manufacturing number. The hardness Hs of the mount rubber 31 changes due to deterioration, and its resonance frequency fo also becomes a value corresponding to the hardness Hs. As an example, an approximately linear relationship holds between hardness Hs and resonance frequency fo. The Ambient Temperature DB20 and Hardness-Resonance Frequency DB21 are pre-generated based on evaluation results and simulation results for each individual vehicle V.

[0016] The terminal 1 executes abnormal noise analysis processing by the CPU 10. The terminal 1 detects the frequency of the abnormal noise contained in the sound acquired by the microphone 12, and estimates the current hardness Hs as the degree of deterioration of the mount rubber 31 from the usage state of the vehicle V. Based on the hardness-resonance frequency DB 21, when the difference between the resonance frequency fo corresponding to the current hardness Hs and the frequency of the abnormal noise is less than or equal to the threshold value, the terminal 1 determines that the mount rubber 31 is the cause of the abnormal noise. The details of the abnormal noise analysis processing will be described below.

[0017] (Abnormal Noise Analysis Processing) FIG. 2 is a flowchart showing an example of the abnormal noise analysis processing. The abnormal noise analysis processing is an example of an abnormal noise analysis method and includes the following processing of steps St1 to St14.

[0018] First, the CPU 10 acquires the sound data of the vehicle V by the microphone 12 and acquires the vehicle information from the storage device 40 (St1). Next, the CPU 10 determines whether the abnormal noise is a vehicle system abnormal noise caused by the tire rotation of the vehicle V or auxiliary equipment such as an air conditioner based on a predetermined operating condition of the vehicle information at the time of the abnormal noise occurrence (St2). As this determination means, for example, the technique described in Japanese Patent Application Laid-Open No. 2023-86329 can be cited, but it is not limited thereto. If the abnormal noise to be analyzed is a vehicle system abnormal noise (Yes in St2), this processing ends.

[0019] Also, when the abnormal noise is not a vehicle system abnormal noise (No in St2), the CPU 10 extracts the frequency components of the sound by performing a fast Fourier transform on the sound data, and calculates the change characteristics of the sound pressure with respect to the frequency and the rotational speed of the engine 3 etc. of the vehicle information (St3).

[0020] FIG. 3 is a diagram showing an example of the change characteristics of the sound pressure. The horizontal axis indicates the frequency of the sound (Hz), and the vertical axis indicates the rotational speed (rpm) of the engine 3 etc. The density of the line indicates the magnitude of the sound pressure, and the darker the part, the greater the sound pressure.

[0021] For example, as indicated by reference sign Pa, when the portion with high sound pressure depends on the order of a specific rotational speed (Yes in St4), the CPU 10 determines that there is a cause of abnormal noise in the power train main body of the vehicle V (St14). Further, for example, as indicated by reference sign Pb, when the portion with high sound pressure does not depend on the order of a specific rotational speed (No in St4) and depends on a specific frequency fi (Yes in St5), the CPU 10 determines that there is a cause of abnormal noise in the power train main body or the mount rubber 31 of the vehicle V (St6). Thus, the CPU 10 detects the frequency of the abnormal noise from the change characteristics of the sound pressure.

[0022] Next, the CPU 10 determines, based on the input of the user of the vehicle V, whether the abnormal noise to be analyzed is an abnormal noise due to aging or an abnormal noise since the vehicle V was purchased (St7). In the case of an abnormal noise since the purchase (No in St7), the CPU 10 determines that there is a cause such as the user's personal perception of sound and ends this process.

[0023] Also, in the case of an abnormal noise due to aging (Yes in St7), the CPU 10 receives the input of the manufacturing number of the vehicle V from the user (St8). Next, the CPU 10 accesses the ambient temperature database (DB) 20 and the hardness-resonance frequency DB 21 of the vehicle V corresponding to the manufacturing number (St9).

[0024] Next, the CPU 10 estimates the current hardness of the mount rubber 31 (St10). For example, the CPU 10 estimates the hardness according to the law that the deterioration rate of the mount rubber 31 doubles with a temperature increase of 10°C, based on the mileage, the usage area, and the ambient temperature among the vehicle information. Note that the average value of the outside air temperature may be used instead of the usage area.

[0025] Next, the CPU 10 calculates the resonant frequency fo of the mount rubber 31 based on the hardness-resonant frequency DB21, according to the current hardness of the mount rubber 31 (St11). Next, the CPU 10 calculates the difference between the resonant frequency fo and the frequency fi of the abnormal noise (=|fo-fi|) (St12). If the difference ≤ K is true (Yes in St12), the deterioration of the mount rubber 31 is determined to be the cause of the abnormal noise (St13). If the difference > K is true (No in St12), the powertrain body of the vehicle V is determined to be the cause of the abnormal noise (St14). Here, K is a threshold value, and as an example, it may be set to 10% of the resonant frequency fo.

[0026] Furthermore, in the sound pressure change characteristics, if the high-sound-pressure portion depends on a specific frequency fi (No. in St5), the CPU 10 determines that the source of the abnormal noise is in the powertrain body of the vehicle V (St14). The abnormal noise analysis process is performed in this manner. This process makes it possible to determine if the abnormal noise is caused by the deterioration of the mount rubber 31. [Explanation of symbols]

[0027] 1 terminal, 10 CPUs, V vehicle, S abnormal noise analysis system

Claims

[Claim 1] The frequency of abnormal noises emanating from the vehicle is detected. The degree of deterioration of the mounting rubber that supports the structure inside the vehicle is estimated from the usage conditions of the vehicle. If the difference between the resonant frequency of the mount rubber corresponding to the degree of deterioration and the frequency of the abnormal noise is less than or equal to a threshold, the mount rubber is determined to be the cause of the abnormal noise. Methods for analyzing abnormal sounds.

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