JP3103765B2 - High-speed running body local noise measurement device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-speed running body local noise measuring device for measuring noise (wheel rolling noise, etc.) generated from a high-speed running body such as a railway vehicle, an automobile, an aircraft, a ship, and the like. About. In particular, the present invention relates to a high-speed running body local noise measurement device capable of reducing the sound (wind noise) generated by the influence of the airflow hitting the measurement device (microphone) itself and measuring the noise to be measured in a more pure form.

[0002]

2. Description of the Related Art In a high-speed railway (such as a Shinkansen), it is one of the important issues to reduce noise generated when the vehicle runs at high speed. As a source of vehicle noise,
There are aerodynamic noises caused by the body turning off the airflow and rolling noises caused by the wheels traveling on the rail while traveling.

[0003]

Problems to be solved when measuring rolling noise are the following three points. The rolling noise is measured by mounting a measuring microphone near the wheel. However, wind noise is generated due to the airflow hitting the microphone, and the noise is generated by the rolling noise of the measurement target. Since the microphone is directly subjected to the vibration generated when the wheel travels on the rail, the microphone may be affected by noise due to the vibration or the microphone may be damaged. Microphones may be damaged by wind pressure or collision objects. When driving at 250 km / h or more,
The wind pressure on the microphone is considerable. In addition, pebbles may be hoisted by an air current accompanying the passage of the vehicle body, and the pebbles may collide with a microphone.

The present invention relates to a device for measuring noise generated from a local portion of a high-speed running body such as a railroad vehicle, wherein the wind noise generated by the influence of the airflow hitting the measuring device itself is reduced as much as possible. It is an object of the present invention to provide a high-speed running body local noise measurement device capable of measuring noise in a more pure form.

[0005]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, a high-speed running vehicle local noise measuring apparatus according to the present invention is mounted outside a high-speed running vehicle, and a noise (wheel rolling) generated from a local portion of the high-speed running body is measured. A microphone, a porous cushioning material surrounding the microphone, and a microphone holder for holding the microphone and the cushioning material inside the microphone, and having a nose before and after the traveling direction of the traveling body. And a microphone holder having a cone and having a slit hole on the side surface extending in the traveling direction.

[0006] By the action of the nose cone of the microphone holder, the wind noise generated by the airflow hitting the measuring device itself is greatly reduced, and the noise in the measurement sound is reduced. If the microphone holder is made of stainless steel or the like, the microphone will not be damaged even if small stones hit it.
In the porous cushioning material existing between the microphone holder and the microphone, a high-speed airflow enters through the slit, and turbulence (turbulence of the airflow) occurs inside the porous cushioning material, and the turbulence hits the diaphragm of the microphone. , To prevent generation of wind noise. It is also for reducing the effect of acceleration applied to the microphone holder. When attaching the microphone holder to the axle box of the axle of the Shinkansen, acceleration of up to 50 G may be applied. Here, “porous” means having external communication holes (open cells).

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a detailed description will be given of a wheel rolling noise measuring device of a high-speed railway with reference to the drawings. First, an outline of a portion to which the high-speed traveling body local noise measurement device (rolling sound measurement device) of the present embodiment is attached will be described. FIG. 5 is a diagram showing a state in which the rolling noise measuring device according to one embodiment of the present invention is mounted near wheels of a Shinkansen vehicle. (A) is a side view, (B) is a front view,
(C) is an enlarged side view of a main part.

In FIG. 5, a rolling noise measuring device 1 is attached to a side of a wheel 103 of a vehicle 101. Specifically, the rolling noise measuring device 1 is attached to the lower surface of the axle box 107 in which the bearing of the wheel 103 is accommodated. Since the rolling noise is generated from the contact portion between the wheel 103 and the rail 105, the rolling noise measuring device 1 is positioned closer to this portion. Note that reference numeral 109 denotes a bogie frame,
111 is a shaft spring, and 113 is a shaft box support device.

Next, details of the rolling noise measuring device of this embodiment will be described. FIG. 1 is a partial cross-sectional side view showing a structure of a rolling noise measuring device according to one embodiment of the present invention. FIG. 2 shows FIG.
FIG. 4 is a front sectional view of a microphone holder main body (type 1) of the rolling sound measuring device of FIG. FIG. 3 is a front sectional view showing the microphone holder main body of the rolling noise measuring device of FIG. 1, and is a diagram showing Type 2 which is thinner and has a larger slit width than that of FIG. 2.

The rolling noise measuring device 1 is mounted on the axle box 5 of the vehicle with the mounting plate 3 via the vibration isolating rubber 37.
The microphone holder 10 of the rolling noise measuring device 1 has a pipe-shaped holder body 13 and nose cones 11 and 19 connected before and after it. Incidentally, the holder body 13 of this example has an outer diameter of 60 mm and a length of 144 mm, and is made of stainless steel.

A slit hole 1 is formed in the wall of the holder body 13.
5 are opened so as to extend in the front-rear direction. The sound to be measured mainly enters the holder through the slit hole. An example of the circumferential distribution of the slit holes 15 is shown in FIGS. Fig. 2 (Type 1) has a thick main body wall (5 mm)
And the slit hole width is narrow (3 mm). FIG. 3 (type 2) is a thin (3 mm) and wide (7 mm) type. The position of the slit hole 15 can be variously changed according to the position and properties of the sound to be measured. Round processing 17 is applied to the outer corners of the microphone holder wall at the front and rear ends of the slit hole 15. This is because the turbulence of the air flow is reduced in this portion, and the wind noise is further reduced.

The nose cones 11 and 19 are for rectifying the airflow hitting the rolling noise measuring device 1, and have a conical shape in this embodiment. These nose cones 11,
Reference numeral 19 denotes a machined stainless steel product, which is screwed to the holder body 13 and is filled with an open cell polyurethane foam 24 as a porous cushioning material.

The microphone holder body 13 is filled with an open cell polyurethane foam 24 which is a porous cushioning material. A microphone 20 is embedded in the center of the urethane foam 24. A cable 25 extends from the tail end of the microphone connector 21, and the cable 25 is led to an extension cord 29 via a connector 27. The microphone 20 has a built-in microphone cartridge 22 and a preamplifier. The diaphragm 23 is provided in the microphone cartridge 22.
Are arranged upright. This is axle box 5
This is to make it difficult to pick up noise due to vertical vibration of the camera.

A support plate 31 and bolts 33 are mounted on the upper part of the microphone holder body 13. The support plate 31 has rounded edges on its front and rear edges to reduce turbulence in the front and rear airflows and to prevent the generation of wind noise.
3 is connected by welding. A total of two bolts 33 are provided before and after, and integrate the support plate 31 and the mounting plate 3. The head of the bolt 33 sinks into a hole on the upper surface of the mounting plate 3. The mounting plate 3 and the anti-vibration rubber 37 to be fitted thereto are attached to the axle axle box 5 with bolts 39 via a ring-shaped anti-vibration rubber 45 and a ring-shaped PVC plastic 47. This prevents direct transmission to the mounting plate A and below.

FIG. 4 is a partial sectional side view showing the internal structure of a rolling noise measuring device according to another embodiment of the present invention. The feature of this rolling noise measuring device is that the tip 43 of the microphone 41 faces downward. The microphone tip 43 faces the center of the slit hole 15 in the direction in which the rolling sound of the measurement object comes. By doing so, the actual state of the rolling noise can be grasped more accurately.
At this time, the posture of the diaphragm 23 in the microphone cartridge 22 may be horizontal as shown in FIG. 4A, or may be vertical as shown in FIG. It may be attached to the mouth of the cartridge 22. However, regarding the point that it is difficult to pick up the vertical vibration of the vehicle body, the form (b) is better.

Next, the results of a wind tunnel experiment performed using the rolling noise measuring device of FIG. 1 (there is no rounded slit hole) will be described. The rolling sound measuring device (both types) of the embodiment of FIG. 1 and a naked microphone are placed in a wind tunnel capable of producing a flow velocity equivalent to 300 km / h, and the microphone is exposed to the wind, and the sound pressure level of each microphone is applied. (Mainly aerodynamic sound pressure) was measured.

FIG. 6 is a graph showing the power spectrum of the measured sound pressure level in a wind tunnel experiment (equivalent to 150 km / h) of the rolling sound measuring device of this embodiment. The top line (open circle) is a line indicating the power spectrum of the naked microphone as the comparative example. The second line (black circle) from the top is a line indicating the power spectrum of the type 1 of this embodiment. The third line (open square) from the top is a line indicating the power spectrum of the type 2 of the present embodiment. The bottom line (black square)
It is a line which shows the power spectrum of background noise.

As shown in FIG. 6, the power spectrum level of the rolling sound measuring device (microphone holder storage type) of this embodiment is significantly lower than that of the comparative example (naked microphone). This effect is greater when the flow velocity is faster (not shown). This is considered to be because wind noise due to the airflow hitting the rolling noise measuring device has been greatly reduced due to the rectifying effect of the nose cone. This experiment was performed up to a wind speed of 300 km / h. However, at a wind speed of 200 km / h or more, it was not possible to measure with a naked microphone due to wind noise of airflow.

In the power spectrum curve of this embodiment shown in FIG. 6, there are some points where the sound pressure level is specifically high. This is considered to be due to the turbulence of the air flow at the edge of the slit hole. Therefore, it is considered that such a point having high wind noise is eliminated by adding a radius (the above-mentioned reference numeral 17 in FIG. 1) to the same portion.

[0020]

As is apparent from the above description, in the local noise measuring apparatus for a high-speed running body according to the present invention, the wind noise generated by the airflow hitting the measuring apparatus itself is greatly reduced by the action of the nose cone of the microphone holder. , Noise in the measurement sound is reduced. Therefore, it is possible to provide a high-speed traveling body local noise measuring device suitable for measuring the noise to be measured in a more pure form.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional side view showing a structure of a rolling noise measuring device according to one embodiment of the present invention.

FIG. 2 is a front sectional view of a microphone holder main body (type 1) of the rolling noise measuring device of FIG. 1;

FIG. 3 is a front sectional view showing a microphone holder main body of the rolling noise measuring device of FIG. 1, and is a diagram showing Type 2 which is thinner and has a larger slit width than that of FIG.

FIG. 4 is a partially sectional side view showing an internal structure of a rolling noise measuring device according to another embodiment of the present invention.

FIG. 5 is a diagram showing a state in which the rolling noise measuring device according to one embodiment of the present invention is mounted near wheels of a Shinkansen vehicle.
(A) is a side view, (B) is a front view, and (C) is an enlarged side view of a main part.

FIG. 6 shows a wind tunnel experiment (1 speed per hour) of the rolling noise measuring device of the present embodiment.
10 is a graph showing a power spectrum of a measured sound pressure level at 50 km / h).

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Rolling noise measuring device 3 Mounting plate 5 Shaft box 10 Microphone holder 11 Nose cone 13 Holder body 15 Slit hole 17 R 19 Nose cone 20 Microphone 21 Microphone connector 22 Microphone cartridge 23 Vibration plate 24 Urethane foam 25 Cable 27 Connector 29 Extension cord 31 Support Plate 33 Bolt 37 Anti-Vibration Rubber 39 Bolt 45 Ring Anti-Vibration Rubber 47 Ring PVC Plastic 51 Sound Introduction Tube 101 Vehicle 103 Wheel 105 Rail 107 Axle Box 109 Undercarriage Frame 111 Axle Spring 113 Axle Box Support Device

Continued on the front page (72) Inventor Jun Matsuo 2-8-8 Hikarimachi, Kokubunji-shi, Tokyo Inside the Railway Technical Research Institute (72) Inventor Masayuki Iketomi 3--20, Higashimoto-cho, Kokubunji-shi, Tokyo 41 Rion Stock In-company (58) Field surveyed (Int.Cl. ⁷ , DB name) G01H 3/00

Claims (3)

(57) [Claims] 1. A device mounted outside of a high-speed running body for measuring noise (wheel rolling noise, etc.) emitted from a local portion of the running body; a microphone; and a porous cushioning material surrounding the microphone And a microphone holder for holding a microphone and a cushioning material therein, the microphone holder having a nose cone before and after the traveling direction of the traveling body, and having a slit hole extending in the traveling direction on a side surface. A high-speed running body local noise measuring device characterized by the above-mentioned. 2. The high-speed running body local noise measuring device according to claim 1, wherein a radius is formed at an outer corner of a microphone holder wall at front and rear ends of the slit hole. 3. The local noise measuring apparatus according to claim 1, wherein a tip of the microphone is directed to a source of the local noise in the microphone holder.