JPH08210100A - Negative pressure wave generator - Google Patents

Abstract

PURPOSE: To provide a negative pressure wave generator that generates strong negative pressure waves. CONSTITUTION: A valve element 102 that opens and closes the gas outlet of a tank 1 accommodating high-pressure air is slowly opened and abruptly closed by means of a hydraulic drive 106 and a driving spring 107 to quickly vary the mass flow of ejected air to obtain strong negative pressure waves. Also, a porous guide 108 guiding the valve element 102 is provided to vary the open area of the valve according to the way a hole is opened, so as to adjust the intensity of the negative pressure waves, and a muffler 4 is also provided at the gas outlet of the tank 1 to deaden noise caused during the ejection of air.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a negative pressure wave generator applied to active noise reduction measures for tunnel micro-pressure waves.

[0002]

2. Description of the Related Art Conventionally, a negative pressure wave generator as shown in FIG. 4 has been used. This negative pressure wave generating device includes a vacuum container 1
By rapidly opening the valve plate 12 of No. 1, the ambient air is rapidly sucked into the vacuum container 11 to generate a negative pressure wave. Specifically, it is driven in the following procedure. First, the valve stem 103 is pushed in using the hydraulic drive device 106, and the valve plate 12 is closed. The inside of the vacuum container 11 is evacuated to a standby state. Next, the valve holding electromagnet 105 is energized to hold the valve plate 12 in the closed position via the valve holding plate 104, and the hydraulic drive device 106 is returned to its original position. When an open command signal is input, the valve holding electromagnet 105 is de-energized, the valve plate 12 is opened at once by the force due to the internal / external pressure difference applied to the drive spring 107 and the valve plate 12, and the ambient air inside the vacuum container 11 is opened. Rapidly inhales, resulting in a negative pressure wave.

[0003]

Generally, the magnitude ΔP of the pressure wave generated from the opening of a gas container such as air is proportional to the time change rate of the mass flow rate m of the ejected gas, and is given by the following equation 1. To be

[0004]

[Equation 1]

Therefore, when the vacuum container is rapidly opened, air is sucked in (m is negative), and in proportion to the increase rate of the suction flow rate,
A negative pressure wave will be obtained. Therefore, in order to obtain a strong negative pressure wave, it is necessary to increase the pressure difference between the inside and the outside and to increase the valve opening area to increase the rate of change of the opening area. In the case of a negative pressure wave generator using, the pressure difference between the inside and outside is limited to 1 atm, and a large vacuum container and a large valve plate are required to increase the valve opening area. Also becomes necessary, the cost becomes high and there is a limit naturally.

The present invention is intended to provide a negative pressure wave generator capable of solving the above problems.

[0007]

The negative pressure wave generator of the present invention takes the following means. (1) A container for storing high-pressure gas, an opening / closing means for opening / closing a gas outlet portion of the container, and a drive device for the opening / closing means that is rapidly closed when the opening / closing means is closed. (2) In the negative pressure wave generator of the above (1), the driving device of the opening / closing means is a device that slowly opens and closes when the opening and closing means is opened and rapidly opens and closes when the opening and closing means is closed. To do. (3) In the negative pressure generator of the above (2), the driving device of the opening / closing means is composed of a hydraulic device and a spring, and when the opening / closing means is opened, the opening / closing means is driven by hydraulic pressure and when the opening / closing means is closed. Is characterized in that the same means is driven by a spring force. (4) In the negative pressure generator of the above (2), the driving device for the opening / closing means includes a cam mechanism and a spring. When the opening / closing means is opened, the opening / closing means is driven by the cam mechanism and the opening / closing means is closed. In this case, the opening / closing means is driven by a spring force. (5) The negative pressure generating device according to the above (1) is characterized in that means for adjusting the opening area of the gas outlet of the container containing the high-pressure gas is provided. (6) In the negative pressure generator of the above (1), a silencer is provided at the gas outlet of the container that contains the high-pressure gas.

[0008]

According to the present invention, if the time rate of change of the mass flow rate m of the gas ejected in the above equation 1 is drastically reduced, the magnitude ΔP of the pressure wave takes a large negative value and a strong negative pressure wave is obtained. It was made paying attention that the mass flow rate m of the ejected gas can be increased without increasing the container size by increasing the storage pressure of the container containing the high-pressure gas.

In the above-mentioned means (1), the opening / closing means of the gas outlet of the container containing the high-pressure gas is rapidly closed by the driving device, so that the mass flow rate m of the gas ejected from the container is negative. It is possible to increase the rate of temporal change of the pressure wave, thereby making the magnitude ΔP of the pressure wave a large negative value and obtaining a strong negative pressure wave. For example,
In the present invention, when the pressure in the tank containing the gas is set to 10 atm, when the opening / closing means having the same opening area is driven at the same speed to open / close the gas outlet, the present invention uses the conventional vacuum container. It is possible to generate a negative pressure wave that is about 10 times stronger than that of a thing.

In the means of the above (2), the above (1)
In addition to the action of the means described above, by slowly opening the opening / closing means for the opening of the container containing the high pressure gas, a large positive pressure wave is prevented from being generated when the opening is opened.

In the above means (3) and (4),
In the means (2), the drive mechanism of the opening / closing means is composed of a hydraulic device and a spring or a cam mechanism and a spring, and when opening / closing the opening of the container, the opening / closing means is slowly opened and abruptly closed. Can be reliably performed.

In the means of the above (5), the above (1)
In addition to the function of the means described above, the opening area of the gas outlet of the container that contains the high-pressure gas is adjusted, and the temporal change rate of the mass flow rate m of the jetted gas is adjusted to obtain a negative pressure wave of arbitrary strength. be able to.

In the means of the above (6), the above (1)
In addition to the function of the means, the audible sound generated when the gas is ejected can be silenced.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to FIGS. In the present embodiment, as shown in FIG. 1, a blow valve 2 that is suddenly closed by a valve drive device 3 is connected to the outlet portion of a high-pressure air tank 1 having a large capacity, and the blow valve 2 and the valve drive device are connected. The blower mechanism 5 is constituted by 3. When the blow valve 2 is opened by the valve drive device 3, the air in the high-pressure air tank 1 is blown through the blow valve 2 through the muffling device 4 that muffles high-frequency jet noise, and the valve drive device When the blowoff valve 2 is suddenly closed at 3, a negative pressure wave proportional to the rate of decrease of the mass flow rate m of air is obtained as shown in Formula 1.

FIG. 2 shows an air blowing mechanism 5 composed of the air blowing valve 2 and the valve driving device 3. Reference numeral 120 denotes a casing connected to the high-pressure air tank 1. The muffler 4 is attached to the side wall of the casing 120, and the muffler 4 includes a porous metal diffuser 111 filled in a through hole 120a in the side wall of the casing 120. I have it.

A hydraulic drive unit 106 constituting the valve drive unit 3 is attached to the side of the casing 120 opposite to the silencer 4, and a rod 106a thereof penetrates the casing 120 and extends into the casing 120, and its tip end. A hollow portion 106b is formed in the portion. A valve body 102 is provided at the tip of the silencer 4 side, and a valve holding plate 104 is provided at an intermediate portion.
The valve rod 103 having the hollow portion 10 has the hollow portion 10 of the rod 106a.
A portion of the tip of the valve rod 103 on the hydraulic drive device 106 side penetrating through 6b is slidably accommodated in the hollow portion 106b.
The hollow portion 1 is provided at the end of the valve rod 103 on the hydraulic device 106 side.
Flange 10 capable of contacting the inner wall of the silencer 4 of 06b
3a is provided.

The valve body 102 is guided by a perforated guide 108 provided in a casing 120 so that the casing 1
20 is movable in the axial direction of the valve rod 103,
The through hole 10 on the side wall of the casing 120 on the silencer 4 side
A valve seat 109 of the valve body 102 is provided around the 2a. In addition, the partition wall 12 between the valve body 102 and the casing 120
A drive spring 107 that biases the valve element 102 toward the valve seat 109 is interposed between 0a.

An intermediate portion of the valve rod 103 slides on a valve holding electromagnet 105 fixed to the casing 120, which is arranged on the hydraulic drive device 106 side of the valve holding plate 104 so as to face the valve holding plate 104. It is possible to penetrate. Further, in the casing 120, the valve body 102 has the valve seat 109.
A fixed shock absorber 110 is provided which contacts the valve retainer plate 104 when seated at.

In FIG. 2, white arrows indicate the flow of air, and solid arrows indicate the movement of the valve element at the time of abrupt closing as described below. Further, the hydraulic drive device 106 and the drive spring 10
The valve drive device 3 shown in FIG. 1 is constituted by 7 and the valve holding electromagnet 105.

In this embodiment having the above structure, the valve body 102 is slowly opened by the hydraulic drive device 106 via the valve rod 103, and the valve holding plate 104 approaches the valve holding electromagnet 105. 105 is energized, and the valve holding electromagnet 105 holds the valve body 102 in the open position shown by the solid line in FIG. Next, the hydraulic drive device 1
When 06 is returned to the original position, the valve holding electromagnet 105 is de-energized at the same timing, and the valve spring 102 is rapidly moved to the right by the force of the drive spring 107 as indicated by the solid arrow in FIG. Moving. The valve holding plate 104 is the shock absorber 110.
The valve body 102 stops when it hits, and then the valve body 102 is seated on the valve seat 109 by the pressure of the high-pressure air tank 1 to rapidly close the valve.

When the valve element 102 is located at the position shown by the solid line in FIG. 2, the air in the high-pressure air tank 1 is jetted into the silencer 4 through the porous metal diffuser 111 as shown by the white arrow. are doing. Then, as mentioned above,
When the valve body 102 moves rapidly and is seated on the valve seat 109 to close the valve, the ejection of air into the silencer 4 is rapidly stopped. Therefore, the negative time change rate of the mass flow rate m of air in this case is very large, and a strong negative pressure wave can be obtained in the silencer 4 and the space connected thereto as described in detail in the action column.

The porous guide 108 is the valve body 102.
Not only to guide the movement of the
The degree of change in the opening area of the valve can be appropriately adjusted, and the strength of the negative pressure wave can be adjusted. Furthermore,
The porous metal diffuser 111 can prevent strong turbulence accompanied by a shock wave generated behind the valve throat portion, and thereby can reduce the high frequency audible generated sound due to the jet flow to around 30 dB.

The second embodiment of the present invention will be described with reference to FIG. In this embodiment, the hydraulic drive unit 106, the valve holding electromagnet 105, and the valve holding plate 104 of the first embodiment are omitted, and the valve rod 103 passes through the valve seat 109 and penetrates the porous metal diffuser 111 to muffle noise. A drive cam 113, which extends into the device 4 and is driven by hydraulic pressure or the like, is arranged at the tip of the valve rod 103 so that it can be engaged / disengaged. Further, a valve stop plate 112 is attached to a portion of the valve rod 103 on the right side (the silencer 4 side) in FIG. 3 from the porous metal diffuser 111, and when the valve rod 103 moves to the right side in FIG. The impact absorbing device 110 that comes into contact with is installed inside the silencer 4.

In this embodiment, the drive cam 113 compresses the drive spring 107 to a position where the valve is fully opened, and the valve rod 103 is opened.
Move and slowly open the valve. Drive cam 11
When 3 is disengaged from the tip of the valve rod 103, the valve rod 103 is rapidly moved to the right in FIG. 3 by the spring force of the drive spring 107, and the valve stop plate 112 of the valve rod 103 is moved to the impact absorbing device 110.
Then, the valve body 102 is seated on the valve seat 109 by the air pressure of the high-pressure air tank 1, and the valve is rapidly closed.

Therefore, this embodiment can also achieve the same operation and effect as the first embodiment.

In the first and second embodiments, the high-pressure air tank 1 is provided with one blowing mechanism having the above-mentioned structure. However, the high-pressure air tank is provided with a plurality of blowing mechanisms. It is also possible to finely adjust the waveform of the negative pressure wave generated by adjusting the sudden closing timing of the valve of the blower mechanism.

[0027]

As described above, the present invention can surely generate a strong negative pressure wave by including the structure described in each claim, and at the same time, the negative pressure wave can be generated. It is possible to adjust the strength of the gas, and to mute the generated sound of the ejected gas.

[Brief description of drawings]

1 shows a negative pressure wave generator according to a first embodiment of the present invention, FIG. 1 (a) is a front view thereof, and FIG. 1 (b) is a side view thereof.

FIG. 2 is a sectional view of an essential part of the embodiment.

FIG. 3 is a sectional view of a main part of a second embodiment of the present invention.

FIG. 4 is a cross-sectional view of a conventional negative pressure wave generator.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 high-pressure air tank 2 blow-off valve 3 valve drive device 4 silencer 5 blow-off mechanism 102 valve body 103 valve rod 104 valve holding plate 105 valve holding electromagnet 106 hydraulic drive device 107 drive spring 108 porous guide 109 valve seat 110 shock absorber 111 porous metal diffuser 112 valve stop plate 113 drive cam 120 casing

Claims (6)

[Claims] 1. A container comprising a high-pressure gas, an opening / closing means for opening / closing a gas outlet of the container, and a drive device for the opening / closing means which is rapidly closed when the opening / closing means is closed. Negative pressure wave generator. 2. The negative pressure wave according to claim 1, wherein the drive device for the opening / closing means is a device for slowly opening / closing the opening / closing means and rapidly opening / closing the opening / closing means. Generator. 3. A drive device for the opening / closing means comprises a hydraulic device and a spring. When the opening / closing means is opened, the opening / closing means is hydraulically driven, and when the opening / closing means is closed, the means is driven by a spring force. The negative pressure wave generator according to claim 2. 4. The drive device for the opening / closing means comprises a cam mechanism and a spring. When the opening / closing means is opened, the opening / closing means is driven by the cam mechanism, and when the opening / closing means is closed, the opening / closing means is driven by a spring force. The negative pressure wave generator according to claim 2. 5. The negative pressure wave generator according to claim 1, further comprising means for adjusting an opening area of a gas outlet portion of a container that stores high-pressure gas. 6. The negative pressure wave generator according to claim 1, wherein a silencer is provided at the gas outlet of the container containing the high-pressure gas.