JP5672801B2 - Underwater sound insulation - Google Patents

Description

  The present invention relates to an underwater sound insulation device.

There is an underwater sound insulation device for insulating sound waves propagating in water.
The underwater sound insulation device is installed, for example, as a baffle behind a sonar provided in a hull, and is used for the purpose of insulating unnecessary sound waves propagating from the rear toward the sonar in water.
As this type of underwater sound insulation device, a device in which hollow spheres covered with a viscoelastic material are integrated, air is enclosed between the hollow spheres, and the periphery thereof is sealed with mold rubber has been proposed (Patent Document 1). reference).
In addition, a plurality of cavities are arranged inside the rubber layer, a flexible container is connected to each cavity through an air passage, and an air pressure equal to the external pressure applied to the flexible container is supplied to each cavity. (See Patent Document 2).

Japanese Patent Publication No. 7-101353 Japanese Patent Publication No. 5-13519

However, in the former underwater sound insulation device, when the external pressure increases, the mold rubber is compressed and deformed, and if the hollow spheres are rigidly joined to each other via the viscoelastic material, there is a disadvantage that the sound insulation effect is lowered.
In the latter underwater sound insulation device, since a plurality of cavities are arranged inside the rubber layer, there is a limit to increasing the ratio of the volume of the whole cavity to the entire underwater sound insulation device, so that the sound insulation effect is reduced. It cannot be said that it is sufficient to reduce the size of the underwater sound insulation device while ensuring it.
The present invention has been made in view of such circumstances, and an object of the present invention is to provide an underwater sound insulation device that can secure sound insulation performance regardless of the magnitude of external pressure and is advantageous for downsizing. is there.

In order to achieve the above object, the present invention provides a plurality of air bags that are made of a viscoelastic material and are inflated by being filled with air, and the plurality of air bags that are adjacent to each other by inflating the air bags. A supporting member that supports the air bags arranged side by side on a flat surface or along a curved surface so that the peripheral surfaces of the matching air bags closely contact each other, an air passage communicating with each air bag, and each air via the air passage And air pressure adjusting means for adjusting the internal pressure, which is the pressure of the air filled in each air bag, and each air bag has a dome-shaped wall with an upper end projecting upward The lower end is supported by the support member and includes a cylindrical bag body that forms the peripheral surface. The adjustment of the internal pressure by the air pressure adjusting means is performed by adjusting the water pressure applied to the air bag. External pressure and inside the air bag When the air pressure is an internal pressure, the external pressure, the internal pressure, and the differential pressure are set within a target differential pressure range, and the target differential pressure range is the peripheral surface of the adjacent air bag by expanding the air bag. It is the underwater sound insulation device characterized by being in the range of the differential pressure sufficient to maintain a state in which the two are in close contact with each other without a gap .

Since the internal pressure can be adjusted according to the increase or decrease of the external pressure to maintain the state where the peripheral surfaces of the air bags are in close contact with each other without any gap, it is advantageous in ensuring sound insulation regardless of the magnitude of the external pressure.
In addition, since the plurality of air bags are supported by the support member, it is advantageous in reducing the size while ensuring sound insulation by securing the thickness of the air layer formed by each air bag.

It is a perspective view which shows the structure of the sound insulation apparatus 10 for underwater. 3 is a cross-sectional view of the air bag 12 and the support member 14. FIG. 3 is a perspective view of a support member 14. FIG. 3 is a block diagram showing a configuration of a control system of the underwater sound insulation device 10. FIG. It is an operation | movement flowchart of the sound insulation apparatus 10 for underwater. It is a figure which shows the experimental result of the sound transmission loss TL in the sound insulation apparatus 10 for underwater.

Next, embodiments of the present invention will be described with reference to the drawings.
As shown in FIGS. 1 and 2, the underwater sound insulation device 10 includes a sound insulation unit 15, an air passage 16, and air pressure adjusting means 18, and is mounted on an underwater structure such as a hull. .

The sound insulation unit 15 includes a plurality of air bags 12 and a support member 14.
The air bag 12 is made of a viscoelastic material and expands by being filled with air.
As the viscoelastic material, various conventionally known materials such as soft rubber having flexibility and synthetic resin having flexibility can be used.
In the present embodiment, the air bag 12 includes a bag body 12A, an opening 12B, and a convex portion 12C.
The bag main body 12A has a cylindrical shape whose upper end is closed by a dome-shaped wall portion having a convex shape upward, and the bag main body 12A has a height H larger than the outer diameter.
The opening 12B is formed at the lower end of the bag body 12A.
The convex portion 12C is formed to bulge out from the inner periphery of the opening 12B to the inside in the radial direction.

The support member 14 has a plurality of air bags 12 on a flat surface or a curved surface so that the peripheral surfaces of the air bags 12 adjacent to each other (the peripheral surface of the bag body 12A) are in close contact with each other as the air bags 12 expand. It supports side by side along the top.
In the present embodiment, as shown in FIGS. 2 and 3, the support member 14 includes a base 14A, a mounting portion 14B, a groove portion 14C, a concave portion 14D, and a base-side air passage 14E. ing.

The base 14 </ b> A has a rectangular plate shape whose upper surface is a flat surface, and is formed of a member having sufficient rigidity to hold the plurality of air bags 12.
As such a member, a rubber material harder than the air bag 12, a synthetic resin material, or a metal plate can be employed.
A plurality of attachment portions 14B are provided on the upper surface of the base 14A so as to be arranged in a lattice pattern, and each attachment portion 14B is formed to protrude in a cylindrical shape from the upper surface of the base 14A.
The groove portion 14C is provided in an annular shape at a location near the base 14A of the attachment portion 14B.
The concave portion 14D is formed in a concave shape toward the upper side inside the attachment portion 14B.
The base-side air passage 14E communicates the concave portions 14D of the adjacent mounting portions 14B.
Further, the end of the base side air passage 14E communicates with the air pressure adjusting means 18 via an external side air passage 20 provided outside the base 14A.

The air bag 12 is supported by the support member 14 by inserting the attachment portion 14B into the opening 12B of the air bag 12 and fitting the convex portion 12C into the groove portion 14C.
Moreover, in FIG. 2, the code | symbol 13 is a clamp which consists of a coil spring wound by ring shape. By attaching the clamp 13 to the outer periphery of the convex portion 12C, the convex portion 12C is pressed against the groove portion 14C, thereby causing the convex portion 12C and the groove portion 14C to be hermetically adhered, and the convex portion 12C falling off from the groove portion 14C. Prevention of this is made.
Each air bag 12 is supported by the support member 14 so that the inside of each air bag 12 communicates with each other via the concave portion 14D and the base-side air passage 14E, and thus the air bags 12 are filled. The internal pressure Pi, which is the air pressure, is the same in each air bag 12.

  The air passage 16 communicates with each air bag 12, and in the present embodiment, the air passage 16 includes a base-side air passage 14E and an external-side air passage 20.

The air pressure adjusting means 18 fills each air bag 12 with air through the air passage 16 and adjusts the internal pressure Pi of each air bag 12.
As shown in FIG. 4, the air pressure adjusting means 18 includes an external pressure sensor 22, an internal pressure sensor 24, a pump drive circuit 26, a pump device 28, an inflow electromagnetic valve 30, an outflow electromagnetic valve 32, and a control unit. 34.
Of the air pressure adjusting means 18, the external pressure sensor 22 and the internal pressure sensor 24 are disposed in the water outside the hull together with the sound insulation unit 15, and the remaining pump drive circuit 26, pump device 28, inflow electromagnetic valve 30, and outflow electromagnetic valve. The valve 32 and the control unit 34 are mounted in a space inside the hull.

The external pressure sensor 22 detects an external pressure Po, which is a water pressure applied to the air bladder 12 in water, and supplies a detection signal to the control unit 34. The external pressure sensor 22 is attached to an appropriate location where the support member 14 is exposed in water, for example.
The internal pressure sensor 24 detects the internal pressure Pi of the air bladder 12 and supplies a detection signal to the control unit 34. For example, the internal pressure sensor 24 is attached to the concave portion 14D of the support member 14.

The pump drive circuit 26 drives the pump device 28 by supplying a drive signal to the pump device 28 based on the control of the control unit 34.
The pump device 28 is driven by a drive signal supplied from the pump drive circuit 26, compresses air, and supplies the compressed air to the inflow electromagnetic valve 30 via the supply air passage 36.
The inflow solenoid valve 30 includes an intake port 30A communicating with the supply air passage 36 and an exhaust port 30B communicating with the external air passage 20, and opens and closes based on a control signal from the control unit 34. It is.
In other words, the inflow electromagnetic valve 30 is provided between the pump device 28 and the air passage 16 and opens and closes between the pump device 28 and the air passage 16.
The outflow solenoid valve 32 includes an intake port 32A communicating with the supply air passage 36, and an exhaust port 32B opened to a space filled with air inside the hull, and is based on a control signal from the control unit 34. Open and close.
In other words, the outflow electromagnetic valve 32 is provided between the air passage 16 and an external space other than underwater, and opens and closes between the air passage 16 and the external space.

  The control unit 34 is constituted by a microcomputer in which, for example, a CPU, a ROM that stores a control program, a RAM that provides a working area, an interface unit that interfaces with peripheral circuits, and the like are connected by a bus. The CPU functions by executing a control program. Here, the peripheral circuits correspond to the external pressure sensor 22, the internal pressure sensor 24, the pump drive circuit 26, the inflow electromagnetic valve 30, and the outflow electromagnetic valve 32.

In the present embodiment, the control unit 34 calculates the value of the differential pressure ΔP = Po−Pi between the external pressure Po obtained from the external pressure sensor 22 and the internal pressure Pi obtained from the internal pressure sensor 24, and this differential pressure ΔP is determined in advance. The pump device 28, the inflow electromagnetic valve 30, and the outflow electromagnetic valve 32 are controlled so as to be within the set target pressure range.
The target pressure range is a range of the differential pressure ΔP that is sufficient to maintain a state in which the peripheral surfaces of the adjacent air bags 12 are in close contact with each other as the air bags 12 expand.
When the differential pressure ΔP is within the target pressure range, an air layer extending along a plane by the air in each air bag 12 in water in order to maintain a state in which the peripheral surfaces of the air bags 12 are in close contact with each other without a gap. As a result, sound waves propagating in water are effectively sound-insulated by this air layer, and sound insulation is ensured.
If the differential pressure ΔP falls below the target pressure range, the air bag 12 is insufficiently expanded and a gap is formed between the peripheral surfaces of the adjacent air bags 12, which is disadvantageous in ensuring sound insulation.
When the differential pressure ΔP exceeds the target pressure range, the inflation of the air bladder 12 becomes excessive, and an excessive force is applied to the air bladder 12, resulting in deterioration of the air bladder 12 and disadvantageous in ensuring durability.

Next, the operation of the underwater sound insulation device 10 will be described with reference to the flowchart of FIG.
It is assumed that the sound insulation unit 15 is previously installed in the water outside the hull, and the portion of the air pressure adjusting means 18 excluding the external pressure sensor 22 and the internal pressure sensor 24 is mounted in the space inside the hull.
In this case, the sound insulation unit 15 is arranged so that the air layer formed by the air filled in each air bag 12 extends in a direction perpendicular to or intersecting with the direction in which the sound wave to be sound-insulated arrives.
In the present embodiment, since the support member 14 (base 14A) has a rectangular plate shape, the sound insulation unit 15 extends so that the base 14A extends in a direction perpendicular to or intersecting with the direction in which the sound wave to be sound insulation arrives. May be arranged.
Note that the sound insulation property does not change whether the sound wave to be sound-insulated is directed to the direction in which the sound wave to be sound-insulated or the opposite direction, and therefore the air bag 12 is directed to any direction.

First, the control unit 34 detects the external pressure Po based on the detection signal from the external pressure sensor 22, and detects the internal pressure Pi based on the detection signal from the internal pressure sensor 24 (step S10).
The controller 34 determines whether or not the differential pressure ΔP = Po−Pi is within the target pressure range (step S12).
If the differential pressure ΔP is within the target pressure range (Yes in step S12), the control unit 34 closes both the inflow electromagnetic valve 30 and the outflow electromagnetic valve 32 and stops the operation of the pump device 28. (Step S14), the process returns to Step S10.

If the differential pressure ΔP is not within the target pressure range (No at Step S12), the control unit 34 determines whether or not the differential pressure ΔP is below the target pressure range (Step S16).
If the differential pressure ΔP falls below the target pressure range (Yes in step S16), the control unit 34 opens the inflow electromagnetic valve 30, closes the outflow electromagnetic valve 32, and operates the pump device 28 ( Step S18). As a result, the air compressed by the pump device 28 is supplied to each air bag 12 via the supply air passage 36, the inflow electromagnetic valve 30, and the air passage 16, and each air bag 12 expands according to the internal pressure. Go. Steps S10, S12, S16, and S18 are repeated until step S12 becomes affirmative.
As a result, as shown in FIG. 2, the peripheral surfaces of the adjacent air bags 12 are brought into close contact with each other without a gap so that the sound insulation is exhibited and the state is maintained.

If the differential pressure ΔP does not fall below the target pressure range (No in step S16), that is, if the differential pressure ΔP exceeds the target pressure range, the control unit 34 closes the inflow electromagnetic valve 30 and uses the outflow The electromagnetic valve 32 is opened and the pump device 28 is stopped (step S20). Thereby, the air in each air bag 12 flows out into the space in the ship body through the air passage 16 and the outflow electromagnetic valve 32, and the internal pressure of each air bag 12 decreases. Then, steps S10, S12, S16, and S20 are repeated until step S12 becomes affirmative.
As a result, as shown in FIG. 2, the peripheral surfaces of the adjacent air bags 12 are brought into close contact with each other without a gap so that the sound insulation is exhibited and the state is maintained.

  When the peripheral surfaces of the adjacent air bags 12 are in close contact with each other without any gap, the sound waves that propagate in the water are reflected by the air layer formed by the air filled in each air bag 12, and the sound waves that propagate in the water. Is attenuated by the action of the viscoelastic material constituting the air bag 12. Thereby, the sound wave propagating in the water is sound-insulated by the sound insulation unit 15.

As described above, according to the underwater sound insulation device 10 of the present embodiment, the air bags 12 are filled with air and the air bags 12 are inflated so that the peripheral surfaces of the adjacent air bags 12 have no gaps. The inner pressure Pi of each air bag 12 is adjusted by arranging and supporting on a flat surface or along a curved surface so as to be in close contact with each other.
Therefore, since the inner pressure Pi can be adjusted according to the increase / decrease of the outer pressure Po to maintain the state in which the peripheral surfaces of the air bladder 12 are in close contact with each other without any gap, it is possible to ensure sound insulation regardless of the magnitude of the outer pressure Po. It will be advantageous.
Moreover, the support member is formed in a desired two-dimensional shape or a three-dimensional shape, and the air layers formed by the air bags 12 are supported by the peripheral surfaces of the adjacent air bags 12 without any gaps. Therefore, it can be easily and reliably formed two-dimensionally or three-dimensionally according to the shape of the above, which is advantageous in ensuring sound insulation appropriately according to the direction of arrival of sound waves.
Moreover, since it was set as the structure which supports the some air bag 12 with the support member 14, the ratio of the whole volume of the air in each air bag 12 to the whole volume of each air bag 12 and the support member 14 is made high. Can do. Therefore, securing the thickness of the air layer formed by each air bag 12 is advantageous in reducing the size of the underwater sound insulation device 10 while ensuring sound insulation.
Furthermore, since the plurality of air bags 12 are supported by the support member 14, no complicated processing is required, the number of parts is small, and the assembly work is easy, which is advantageous in reducing the manufacturing cost. Become.

When the sound insulation unit 15 is installed in water having a very large depth, the external pressure Po becomes extremely high, so that it may be difficult to send compressed air into the air bag 12 depending on the capability of the pump device 28. is there.
In that case, before putting the sound insulation unit 15 into the water, the compressed air is sent into the air bag 12 in advance and the internal pressure Po of the air bag 12 is adjusted to a magnitude corresponding to the predicted external pressure Po, In this state, the sound insulation unit 15 may be installed in water.
In this case, the pump device 28 only needs to have a capability of sending compressed air sufficient to adjust the differential pressure ΔP, which is advantageous in reducing the cost of the pump device 28.

Further, when the sound insulation unit 15 is installed in water having a relatively small depth, the internal pressure Po of the air bag 12 is predicted by sending compressed air into the air bag 12 before putting the sound insulation unit 15 into the water, as described above. It is good to adjust to the magnitude | size corresponding to the external pressure Po performed.
In this case, since the external pressure Po is relatively small, there is a high possibility that the differential pressure ΔP is within the target differential pressure range without performing the adjustment operation of the differential pressure ΔP by the control unit 34. This is advantageous for the suppression.
In the present embodiment, the case where the air pressure adjusting means 18 automatically adjusts the internal pressure Pi of each air bag 12 by the control unit 34 has been described. However, the internal pressure Pi of each air bag 12 is manually adjusted as follows. You may adjust.
In this case, an operation unit including a manually operable switch that gives an operation command to the control unit 34 is provided. Based on the operation of the operation unit, the control unit 34 performs the pump drive circuit 26, the pump device 28, the inflow electromagnetic valve 30, The internal pressure Pi of each air bag 12 may be adjusted by controlling the operation of the outflow electromagnetic valve 32.

Next, an experimental result of sound transmission loss in the underwater sound insulation device 10 will be described.
FIG. 6 shows experimental results, in which the horizontal axis represents the frequency f (kHz) of sound propagating in water, and the vertical axis represents the sound transmission loss TL (dB).
The sound transmission loss TL is a numerical value indicating the sound insulation performance of the member, and is indicated by a ratio between the magnitude of the sound incident on the member and the sound transmitted through the member. The larger the numerical value, the better the sound insulation performance. It shows that there is.
The experiment was conducted with the height H of the bag body 12A set to 20 mm, 40 mm, and 80 mm.
As apparent from FIG. 6, the difference in the sound transmission loss TL depending on the height H is not significant in the range of 10 kHz to 20 kHz, but the sound transmission loss is increased as the height H is increased in the range of 20 kHz to 100 kHz. It was found that a large TL can be secured and the sound insulation is excellent.
This is presumably because the thickness of the air layer formed by the plurality of air bags 12 increases in proportion to the height H of the bag body 12A.

  DESCRIPTION OF SYMBOLS 10 ... Sound insulation device for underwater, 12 ... Air bag, 14 ... Support member, 16 ... Air passage, 18 ... Air pressure adjusting means, 22 ... External pressure sensor, 24 ... Internal pressure sensor, 28 ... Pump device , 34... Control unit, Pi... Internal pressure, Po... External pressure, .DELTA.P.

Claims (3)

A plurality of air bags made of a viscoelastic material and inflated by being filled with air;
A support member for supporting the plurality of air bags side by side on a plane or along a curved surface so that the peripheral surfaces of the adjacent air bags are in close contact with each other by inflating the air bags;
An air passage communicating with each air bag;
Air pressure adjusting means for filling each air bag with air through the air passage and adjusting an internal pressure which is a pressure of air filled in each air bag ;
Each of the air bags is configured to include a bag body having a cylindrical shape whose upper end is closed by a dome-shaped wall portion having a convex shape upward, and whose lower end is supported by the support member and forms the peripheral surface,
The adjustment of the internal pressure by the air pressure adjusting means is such that when the water pressure applied to the air bag is an external pressure and the air pressure in the air bag is an internal pressure, the external pressure, the internal pressure, and the differential pressure are within a target differential pressure range. Made
The target differential pressure range is a range of the differential pressure sufficient to maintain a state in which the peripheral surfaces of adjacent air bags are in close contact with each other as the air bags expand.
A sound insulation device for underwater. The air pressure adjusting means is
An external pressure sensor for detecting the water pressure applied to the air bag as an external pressure;
An internal pressure sensor for detecting an air pressure in the air bag as an internal pressure;
A pump device for supplying compressed air to the air passage;
A controller that calculates a differential pressure between the external pressure and the internal pressure, and that controls an operation of the pump device based on the differential pressure;
Control of the operation of the pump unit by the control unit, the pressure difference Ru made to be within the target differential pressure range,
The underwater sound insulation device according to claim 1. The air pressure adjusting means is
An external pressure sensor for detecting the water pressure applied to the air bag as an external pressure;
An internal pressure sensor for detecting an air pressure in the air bag as an internal pressure;
A pump device for supplying compressed air to the air passage;
An inflow solenoid valve that is provided between the pump device and the air passage and opens and closes between the pump device and the air passage;
An outflow solenoid valve that is provided between the air passage and an external space other than underwater, and opens and closes between the air passage and the external space;
And calculating a differential pressure between the external pressure and the internal pressure, and including a controller that controls the operation of the pump device and the inflow solenoid valve and the outflow solenoid valve based on the differential pressure,
Control of the operation of the pump unit by the control unit, the pressure difference Ru made to be within the target differential pressure range,
The underwater sound insulation device according to claim 1.

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