Acoustic acquisition device for vehicle rolling part in tunnel environment

Abstract

The invention belongs to the field of tunnel sound collection, and discloses a vehicle rolling part acoustic collection device in a tunnel environment, which comprises an acoustic cavity, a microphone assembly and a microphone signal transfer box, one side of the acoustic cavity is provided with an opening in a hollow mode, the hollow area forms a pickup cavity, and the pickup cavity is arranged in an oval mode with the opening plane as the reference; the microphone assembly comprises a fixing piece, a front cavity and a collection head and is arranged in a pickup cavity of the acoustic cavity; the collection head is provided with a plurality of collection holes, and the direction of the collection holes is towards the pickup cavity. And the microphone signal transfer box is electrically connected with the microphone assembly and is used for processing and filtering the microphone front acquisition signal. According to the method, signal preprocessing is carried out from hardware, the quality and requirements of signals can be guaranteed before algorithm processing, and the workload of later development is reduced.

Description

Technical Field

[0001] The present invention belongs to the field of tunnel sound acquisition, and specifically relates to an acoustic acquisition device for vehicle rolling components in a tunnel environment. Background Art

[0002] During the service process of urban rail transit vehicles, many problems are often encountered. In particular, the rotating components at the bottom of the vehicle often malfunction and cause abnormal sounds. The reason is the abnormal rolling body friction caused by internal damage. Currently, by installing an acoustic acquisition system beside the track, the fault sounds can be effectively acquired and discriminated. The existing technologies, especially the acquisition units, have the following problems: The acquisition box of the traditional separate (6) vehicle-side acoustic units does not have internal sound field regulation, such as focusing, noise reduction, etc. The known publicly patented acquisition units are only general box structures, and the built-in sound field has not been deeply studied, especially the regulation of the sound field by their structures; The traditional acquisition core components use microphones or microphones, and the installation method is mainly facing the sound source. Although this method can directly obtain the sound signal, it is easily affected by the environment for a long time. If the sound pickup surface is not protected by an external acquisition box, it is easily contaminated; The traditional acquisition system does not design the microphone and hardware to ensure the effectiveness of the acquired sound signal. It only relies on algorithm processing. This method is relatively single and cannot perform pre-processing on the sound signal from the front end of the acquisition device, which will increase the difficulty of post-processing. Summary of the Invention

[0003] In view of this, the present invention provides an acoustic acquisition device for vehicle rolling components in a tunnel environment to solve the above problems.

[0004] To solve the above technical problems, the present invention provides an acoustic acquisition device for vehicle rolling components in a tunnel environment, including: An acoustic cavity, a microphone assembly, and a microphone signal transfer box; The acoustic cavity is hollow with an opening on one side. The hollow area forms a sound pickup cavity, and the sound pickup cavity is elliptical with its opening plane as the reference; The microphone assembly includes a fixing member, a front cavity, and a collection head, which is arranged in the sound pickup cavity of the acoustic cavity; multiple collection holes are arranged on the collection head, and the orientation of the collection holes is towards the sound pickup cavity; The microphone signal transfer box is electrically connected to the microphone assembly and is used for processing and filtering the pre-acquired microphone signals.

[0005] As an optional method, it further includes a mounting bracket for carrying the acoustic cavity and the microphone signal transfer box.

[0006] As an alternative, the sound pickup cavity includes a first structural edge and a second structural edge, the first structural edge and the second structural edge are perpendicular to each other, and any one of the structural edges is symmetrically arranged in the normal direction of the acoustic cavity; wherein, the first structural edge and the second structural edge are arranged in an arc shape.

[0007] As an alternative, the first structural edge gradually inclines from the opening side of the sound pickup cavity towards the side away from the opening.

[0008] As an alternative, the starting point of the first structural edge is connected to the perpendicular line of the sound pickup cavity opening plane, and the ending point of the first structural edge is connected to the first edge of the sound pickup cavity opening plane.

[0009] As an alternative, the first structural edge gradually inclines towards the side away from the sound pickup cavity opening, and the slope of the inclination is constant.

[0010] As an alternative, the second structural edge gradually inclines from the opening side of the sound pickup cavity towards the side away from the opening.

[0011] As an alternative, the starting point of the second structural edge is connected to the perpendicular line of the sound pickup cavity opening plane, and the ending point of the second structural edge is connected to the second edge of the sound pickup cavity opening plane.

[0012] As an alternative, the second structural edge gradually inclines towards the side away from the sound pickup cavity opening, and the slope of the inclination is constant.

[0013] As an alternative, the starting points of the first structural edge and the second structural edge are connected to the perpendicular line of the sound pickup cavity opening plane, the ending point of the first structural edge is connected to the first edge of the sound pickup cavity opening plane, and the ending point of the second structural edge is connected to the second edge of the sound pickup cavity opening plane; wherein, the first edge and the second edge are perpendicular to each other.

[0014] The beneficial effects of the present invention are as follows: The present invention performs pre-processing of signals from the hardware itself, can ensure the quality and requirements of signals before algorithm processing, and reduce the workload of later development. Description of the Drawings

[0015] Figure 1 It is a schematic layout diagram of the acoustic acquisition device provided by an embodiment of the present invention; Figure 2 It is a partially enlarged schematic diagram of the acoustic acquisition device provided by an embodiment of the present invention; Figure 3 It is a schematic diagram of the acoustic cavity structure provided by an embodiment of the present invention; Figure 4 It is a mapping frequency diagram of the aperture adjustment of the microphone capsule provided by an embodiment of the present invention; Figure 5 This is the simulated sound field energy distribution diagram provided by the embodiment of the present invention.

[0016] Reference numerals and their corresponding relationships: 1 - acoustic cavity, 11 - first structural edge, 12 - second structural edge, 2 - microphone assembly, 21 - fixing member, 22 - front cavity, 23 - acquisition head, 24 - acquisition hole, 3 - microphone signal transfer box, 4 - mounting bracket, 51 - first edge, 52 - second edge. Specific implementation manners

[0017] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below in conjunction with specific implementation manners.

[0018] Please refer to Figures 1 - 3 , this embodiment provides an acoustic acquisition device for vehicle rolling components in a tunnel environment, including: an acoustic cavity 1, a microphone assembly 2 and a microphone signal transfer box 3; the acoustic cavity 1 is hollowly arranged with one side open, and the hollow area forms a sound pickup cavity, and the sound pickup cavity is elliptically arranged with its opening plane as a reference; the microphone assembly 2 includes a fixing member 21, a front cavity 22 and an acquisition head 23, and it is arranged in the sound pickup cavity of the acoustic cavity 1; a plurality of acquisition holes 24 are arranged on the acquisition head 23, and the orientation of the acquisition holes 24 is towards the sound pickup cavity; the microphone signal transfer box 3 is electrically connected to the microphone assembly 2 and is used for processing and filtering the pre-acquired microphone signals. And a mounting bracket 4, and the mounting bracket 4 is used to carry the acoustic cavity 1 and the microphone signal transfer box 3.

[0019] In this embodiment, the mounting bracket 4 is mainly responsible for carrying the body structure of the acoustic cavity 1. Due to the requirements of lightweight design and installation conditions, a leveling structure is added to the bottom of the bracket to ensure the installation requirements of the box body and the ground. In an implementable scenario, it can adapt to the range between a wheel diameter of 770 mm and 860 mm and has the installation condition of the ballast surface with a distance of 30 - 100 mm from the bottom of the rail. In such a scenario, the acoustic cavity 1 in this embodiment adopts an internal elliptical surface structure design. Through simulation analysis and adjustment, it is ensured that it has a certain sound field focusing function, can regulate the sound field, and at the same time ensure the long-term normal operation of the sound pickup device. In addition, the pre-processing algorithm can effectively adapt to the reverberant working environment inside the tunnel and further improve the sound pickup effect. Optionally, its bottom adopts a four-screw leveling design to ensure a flat installation. The bracket structure is simple, ensuring the basic load-bearing requirements and being hollow, reducing the total weight and realizing miniaturization. The lateral opening sound pickup range of the acoustic cavity 1 body is 2 - 2.4 m, and the longitudinal opening sound pickup range can cover the bearing.

[0020] Please refer to again Figures 2 - 3 , this embodiment is implemented as follows: The sound pickup cavity includes a first structural edge 11 and a second structural edge 12. The first structural edge 11 and the second structural edge 12 are perpendicular to each other, and any one of the structural edges is symmetrically arranged in the normal direction of the acoustic cavity 1. Among them, the first structural edge 11 and the second structural edge 12 are arc-shaped. The first structural edge 11 gradually inclines from the opening side of the sound pickup cavity towards the side far from the opening. The starting point of the first structural edge 11 is connected to the perpendicular line of the sound pickup cavity opening plane, and the end point of the first structural edge 11 is connected to the first edge 51 of the sound pickup cavity opening plane. The first structural edge 11 gradually inclines towards the side far from the sound pickup cavity opening, and the inclination slope is constant. The second structural edge 12 gradually inclines from the opening side of the sound pickup cavity towards the side far from the opening. The starting point of the second structural edge 12 is connected to the perpendicular line of the sound pickup cavity opening plane, and the end point of the second structural edge 12 is connected to the second edge 52 of the sound pickup cavity opening plane. The second structural edge 12 gradually inclines towards the side far from the sound pickup cavity opening, and the inclination slope is constant. Among them, the first edge 51 and the second edge 52 of the opening plane are respectively connected to the first structural edge 11 and the second structural edge 12, and the first edge 51 and the second edge 52 are perpendicular to each other.

[0021] Through the design of the above structure, the acoustic cavity 1 of this embodiment adopts "double arc surface" acoustic reflection, and the sound pickup range of the track direction is controlled by the arc surfaces on both transverse sides, and the longitudinal elliptical arc surface realizes the focusing effect of the sound source signal. This embodiment conducts simulation modeling on it. The process mainly sets the frequencies to 0.5 kHz, 2 kHz, 8 kHz, 12.5 kHz, and 16 kHz respectively, and extracts the sound pressure curves at the microphone sound pickup position and the sound pressure distribution map at the focusing moment under two working conditions of the presence and absence of the acoustic cavity 1. At the same time, the peak-to-peak values of the sound pressure under various working conditions are extracted, and the amplification factor is calculated. It can be estimated that the use of the acoustic cavity 1 can significantly amplify the energy of the sound source signal, and the higher the frequency of the sound source, the better the amplification effect. The specific can be referred to the following table:

[0022] It can be seen that the design effect of the acoustic cavity in this embodiment can significantly increase the amplification effect of the signal. The amplification factor is between 3.8 and 6.1, and it adapts to the high-frequency characteristics of the rolling body in tunnel detection, that is, the amplification factor increases with the increase of frequency.

[0023] In addition, this embodiment designs two parameters, namely the front cavity volume of the microphone capsule and the capsule aperture, and simulates an optimal design with a band-pass effect. The design method is as follows: (1)Adjust the aperture of the microphone diaphragm (0.45 mm, 0.5 mm, 0.6 mm) and study and analyze the "frequency - sound pressure curve". The conclusion is that as the aperture increases and the inner cavity diameter remains unchanged, the peak value of the resonant frequency of the cavity moves towards the high - frequency direction, and the amplitude decreases. However, the resonant frequency of the mapped model is basically locked in the range of about 10 kHz, as Figure 4 shown.

[0024] (2)Adjust the front - cavity aperture of the microphone diaphragm (5 mm, 5.2 mm, 5.4 mm) and study and analyze the "frequency - sound pressure curve". The conclusion is that as the front - cavity diameter (volume) increases and the aperture remains unchanged, the peak value of the resonant frequency of the cavity remains stable at about 10 kHz, and only the amplitude of the peak value slightly increases with the increase of the aperture.

[0025] (3)Adjust the front - cavity depth of the microphone diaphragm (0.76 mm, 0.96 mm, 1.16 mm, 1.36 mm, 1.56 mm) and study and analyze the "frequency - sound pressure curve". The conclusion is that as the cavity depth increases, the peak value of the frequency response gradually moves towards the low - frequency direction. That is, the curve shows that for a front - cavity depth of 0.76 mm, the high - frequency response > 10 kHz. When the depth increases, the peak gradually moves towards the low - frequency direction.

[0026] At the same time, it is determined that the microphone is arranged in a way that it faces away from the sound source and towards the inside of the acoustic cavity. After simulating the changes in the acoustic field inside the cavity, it can be found that the first maximum reflection can be obtained at the arc - surface focusing position, and then the energy gradually decreases. Therefore, placing the microphone inward can collect the first maximum peak. As Figure 5 shown.

[0027] In addition, the signal transfer box in this embodiment is designed to adopt a single - channel independent acquisition and processing method to avoid mutual interference and influence between channels. This part of the design requires independent acquisition of multi - channel signals, synchronous triggering, and ensuring a certain pre - filtering effect. The difference from other systems is that there is no physical isolation between channels, and using a single - channel and single - pre - processing method can further avoid interference. The main design points of signal transfer are to supply power to the microphone, amplify the signal, convert it into a differential signal, and transmit it.

[0028] Through the above design, this embodiment performs pre - processing of signals from the hardware itself, which can ensure the quality and requirements of signals before algorithm processing and reduce the workload of later development. The first use of autonomous simulation and structural optimization of the microphone diaphragm can control the sound source signal to a specific frequency band, achieve localization, and reduce hardware costs.

[0029] The above are only the preferred embodiments of the present invention. It should be noted that the above preferred embodiments should not be construed as limiting the present invention, and the protection scope of the present invention should be subject to the scope defined by the claims. For those of ordinary skill in the art, several improvements and modifications can be made without departing from the spirit and scope of the present invention, and these improvements and modifications should also be regarded as within the protection scope of the present invention.

Claims

1. An acoustic collection device for rolling parts of a vehicle in a tunnel environment, characterized in that: include: Acoustic cavity, microphone assembly and microphone signal transfer box; The acoustic cavity is hollow with one side open, the hollow area forms a sound pickup cavity, and the sound pickup cavity is elliptical with its opening plane as a reference; The microphone assembly includes a fixing part, a front cavity and a collection head, which is arranged in the sound pickup cavity of the acoustic cavity; a plurality of collection holes are arranged on the collection head, and the direction of the collection holes is toward the direction of the sound pickup cavity; The microphone signal transfer box is electrically connected to the microphone assembly and is used for processing and filtering the microphone preamplifier signal.

2. The acoustic collection device for rolling parts of a vehicle in a tunnel environment according to claim 1, characterized in that: It also includes a mounting bracket, which is used to support the acoustic cavity and the microphone signal transfer box.

3. The acoustic collection device for rolling components of a vehicle in a tunnel environment according to claim 1, characterized in that: The sound pickup cavity includes a first structural edge and a second structural edge, the first structural edge and the second structural edge are perpendicular to each other, and any of the structural edges are symmetrically arranged in the normal direction of the acoustic cavity; wherein the first structural edge and the second structural edge are arranged in an arc shape.

4. The acoustic collection device for rolling components of a vehicle in a tunnel environment according to claim 3, characterized in that: The first structural edge is gradually inclined along the opening side of the sound pickup cavity toward a direction away from the opening side.

5. The acoustic collection device for rolling parts of a vehicle in a tunnel environment according to claim 4, characterized in that: The starting point of the first structural edge is connected to a vertical line of the opening plane of the sound pickup cavity, and the ending point of the first structural edge is connected to a first edge of the opening plane of the sound pickup cavity.

6. The acoustic collection device for rolling parts of a vehicle in a tunnel environment according to claim 4, characterized in that: The first structural edge is gradually inclined toward the side away from the opening of the sound pickup cavity, and the inclination slope is constant.

7. The acoustic collection device for rolling components of a vehicle in a tunnel environment according to claim 3, characterized in that: The second structural edge is gradually inclined along the opening side of the sound pickup cavity toward a direction away from the opening side.

8. The acoustic collection device for rolling components of a vehicle in a tunnel environment according to claim 7, characterized in that: The starting point of the second structural edge is connected to a vertical line of the opening plane of the sound pickup cavity, and the ending point of the second structural edge is connected to a second edge of the opening plane of the sound pickup cavity.

9. The acoustic collection device for rolling parts of a vehicle in a tunnel environment according to claim 8, characterized in that: The second structural edge is gradually inclined toward the side away from the opening of the sound pickup cavity, and the inclination slope is constant.

10. The acoustic collection device for rolling parts of a vehicle in a tunnel environment according to claim 3, characterized in that: The starting points of the first structural edge and the second structural edge are connected to the vertical line of the pickup cavity opening plane, the end point of the first structural edge is connected to the first edge of the pickup cavity opening plane, and the end point of the second structural edge is connected to the second edge of the pickup cavity opening plane; wherein the first edge and the second edge are perpendicular to each other.

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