Acoustic window

Abstract

To provide an acoustic window advantageous for improving durability.SOLUTION: An acoustic window 10A comprises: a mounting part 12 that is attached to an underwater structure-side mounting part 4 provided around an opening of a sonar chamber 6 that is provided in an underwater structure 2 and houses a sonar device; and a shielding part 14 that has acoustic transparency, is provided inside the mounting part 12, and formed in a rectangular plate shape to close the opening. The mounting part 12 comprises a frame-shaped mounting body part 16 that is attached to the underwater structure-side mounting part 4, and a frame-shaped mounting projection part 18 that protrudes toward the opening from a location along the entire inner circumferential length of the mounting body part 16. The shielding part 14 is provided inside the mounting projection part 18. An inner surface of the mounting projection part 18 located on the sonar chamber 6 side is formed as an inclined surface 20 that is inclined in a direction that the thickness of the mounting projection part 18 decreases gradually toward the shielding part 14.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to an acoustic window. [Background technology]

[0002] Sonar devices installed on underwater structures such as ships have traditionally been used to search for obstacles ahead, such as whales or driftwood, to ensure safe navigation. Also, sonar devices are installed on the bottom of fishing boats and oceanographic research vessels to detect schools of fish and perform various measurements on the seabed. The sonar device is installed in a sonar room provided in the underwater structure, and the opening of the sonar room is blocked with an acoustic window that allows sound waves to pass through, while the sonar room is filled with a liquid such as water or oil, so that the sonar device can efficiently send and receive sound waves. Patent Document 1 discloses an acoustic window that includes a frame-shaped mounting portion that is attached to a mounting portion on the underwater structure side around the opening, and a plate-shaped shielding portion that is acoustically transparent and is located inside the mounting portion to block the opening, and the plate-shaped shielding portion has a rubber core layer with fiber-reinforced resin skin layers on both sides. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-90075 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the above-described conventional technology, there are portions where the cross-sectional shape of the joint between the frame-shaped mounting portion and the plate-shaped shielding portion changes suddenly. Therefore, when a load is applied to the shielding part from underwater, stress is concentrated at the point where the cross-sectional shape of the joint changes suddenly, so there is room for improvement in ensuring the durability of the joint between the frame-shaped mounting part and the plate-shaped shielding part. The present invention has been devised in view of the above circumstances, and an object of the present invention is to provide an acoustic window that is advantageous in terms of improving durability. [Means for solving the problem]

[0005] In order to achieve the above-mentioned object, one embodiment of the present invention is an acoustic window comprising: a frame-shaped mounting portion attached to an underwater structure-side mounting portion around the opening of a sonar chamber provided in an underwater structure; and a plate-shaped shielding portion that is acoustically transparent and is provided inside the mounting portion and blocks the opening, wherein the mounting portion comprises a frame-shaped mounting main body portion attached to the underwater structure-side mounting portion, and a frame-shaped mounting protrusion portion that protrudes toward the opening from a location along the entire length of the inner periphery of the mounting main body portion, the shielding portion is provided inside the mounting protrusion, and the inner surface of the mounting protrusion located on the sonar chamber side is formed with an inclined surface that slopes in a direction gradually thinner as it approaches the shielding portion, and the mounting portion is characterized by including a frame-shaped metal member provided across the mounting main body portion and the mounting protrusion portion, and a fiber-reinforced resin covering portion that covers the metal member. In addition, one embodiment of the present invention is characterized in that a frame-shaped acoustic member made of an elastic material is arranged in place of the metal member provided on the mounting protrusion along the entire length of the inner periphery of the metal member. In one embodiment of the present invention, the hardness of the acoustic member is JIS K 6253 Type A 72 degrees or more and 82 degrees or less. In one embodiment of the present invention, the shielding portion includes an outer fiber-reinforced resin layer located on the underwater side, an inner fiber-reinforced resin layer located on the sonar chamber side, at least one intermediate fiber-reinforced resin layer provided between the outer fiber-reinforced resin layer and the inner fiber-reinforced resin layer, and a plurality of elastic material layers provided between the outer fiber-reinforced resin layer, the inner fiber-reinforced resin layer, and the intermediate fiber-reinforced resin layer; and the covering portion includes an outer covering portion located on the underwater side, an inner covering portion that forms the portion of the attachment main body located on the sonar chamber side, and an inclined covering portion that is continuous with the inner covering portion and forms the inclined surface, and the outer fiber-reinforced resin layer is provided integrally with the outer covering portion, and the inner fiber-reinforced resin layer and the intermediate fiber-reinforced resin layer are provided integrally with the inclined covering portion. [Effects of the Invention]

[0006] According to one embodiment of the present invention, the inner surface of the mounting protrusion located on the sonar room side is formed with an inclined surface that gradually slopes in the direction of making the thickness of the mounting protrusion thinner as it approaches the shielding portion. This is advantageous in preventing stress from concentrating at the boundary between the inclined surface of the inner surface of the mounting protrusion and the inner surface of the shielding portion when a load is applied to the shielding portion from underwater, and is advantageous in improving the durability of the acoustic window. In addition, the mounting portion is composed of a frame-shaped metal member that spans the mounting main body and the mounting protrusion, and a fiber-reinforced resin covering that covers the metal member, which is advantageous for increasing the strength of the mounting portion and improving the durability of the acoustic window. Furthermore, if a frame-shaped acoustic member made of an elastic material is disposed along the entire length of the inner periphery of the metal member provided on the mounting protrusion, the stress generated at the boundary between the inclined surface of the inner surface of the mounting protrusion and the inner surface of the shielding portion is dispersed by the frame-shaped acoustic member made of an elastic material, which is advantageous in improving the durability of the acoustic window. The acoustic member also helps to suppress reflection and interference of sound waves emitted from the sonar device, which is advantageous in improving the detection performance of the sonar device. Furthermore, the acoustic member also absorbs and damps vibrations generated in the underwater structure, which is advantageous in improving the detection performance of the sonar device. In addition, setting the hardness of the acoustic member 34 to JIS K 6253 Type A 72 degrees or more and 82 degrees or less is advantageous in terms of improving the durability of the acoustic window 10A, ensuring that the acoustic member 34 absorbs some of the sound waves emitted from the sonar device, and ensuring that the vibrations of the underwater structure 2 are absorbed and damped. Furthermore, if the shielding portion is configured to include an outer fiber-reinforced resin layer, an inner fiber-reinforced resin layer, at least one intermediate fiber-reinforced resin layer provided between the outer fiber-reinforced resin layer and the inner fiber-reinforced resin layer, and an elastic material layer provided between the outer fiber-reinforced resin layer, the inner fiber-reinforced resin layer, and the intermediate fiber-reinforced resin layer, this is advantageous in improving the durability of the acoustic window by ensuring the strength of the shielding portion while ensuring the acoustic properties of the shielding portion. Furthermore, if the covering portion comprises an outer covering portion, an inner covering portion, and an inclined covering portion that is continuous with the inner covering portion and forms an inclined surface, and the outer fiber-reinforced resin layer is formed integrally with the outer covering portion, and the inner fiber-reinforced resin layer and the intermediate fiber-reinforced resin layer are formed integrally with the inclined covering portion, this is advantageous in improving the attachment strength of the shielding portion to the attachment portion, thereby improving the durability of the acoustic window. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a perspective view of an acoustic window according to a first embodiment, as seen from outside a sonar room. FIG. [Figure 2] FIG. 2 is a perspective view of the acoustic window according to the first embodiment, as seen from the sonar room side. [Figure 3]FIG. 2 is a cross-sectional view taken along line XX in FIG. [Figure 4] FIG. 2 is a cross-sectional view taken along line YY in FIG. [Figure 5] 10 is a cross-sectional view of an acoustic window according to a second embodiment, corresponding to FIG. 3. [Figure 6] 5 is a cross-sectional view of an acoustic window according to a second embodiment, corresponding to FIG. 4. DETAILED DESCRIPTION OF THE INVENTION

[0008] (First embodiment) First, an acoustic window according to a first embodiment will be described with reference to FIGS. As shown in Figures 3 and 4, the acoustic window 10A comprises an attachment portion 12 attached to the attachment portion 4 on the underwater structure around the opening of the sonar chamber 6, which is provided in the underwater structure 2 and houses a sonar device (not shown), and a rectangular plate-shaped shielding portion 14 that is acoustically transparent and is provided inside the attachment portion 12 to block the opening. The sonar device emits sound waves to an underwater object through the acoustic window 10A (shielding portion 14) shown in Figures 1 and 2, and detects the positional relationship between the underwater structure 2 and the object by receiving the reflected waves. The acoustic window 10A has a horizontally long rectangular shape having a width and a length that is greater than the width. The opening of the sonar room 6 has a horizontally long rectangular shape, and multiple acoustic windows 10A are attached to the opening, arranged in a straight line with their longitudinal direction aligned with the longitudinal direction of the opening, so that the opening is blocked by the multiple acoustic windows 10A.

[0009] As shown in Figures 3 and 4, the mounting portion 12 comprises a frame-shaped mounting main body 16 with a rectangular cross section that is attached to the mounting portion 4 on the underwater structure side, and a frame-shaped mounting protrusion 18 with a trapezoidal cross section that protrudes toward the opening from a location along the entire length of the inner periphery of the mounting main body 16, and the shielding portion 14 is provided inside the mounting protrusion 18.

[0010] The inner surface of the mounting protrusion 18 located on the sonar chamber 6 side is formed with an inclined surface 20 that gradually slopes in the direction of making the thickness of the mounting protrusion 18 thinner as it approaches the shielding portion 14, and the outer surface of the mounting protrusion 18 located on the underwater side is located on the same plane as the outer surface of the mounting main body portion 16.

[0011] The mounting portion 12 is configured to include a frame-shaped metal member 22 that spans the mounting main body 16 and the mounting protrusion 18, and a fiber-reinforced resin covering portion 24 that covers the metal member 22. The covering portion 24 comprises an outer covering portion 24A located on the underwater side, an inner covering portion 24B that forms the part of the mounting main body portion 16 located on the sonar room 6 side, an inclined covering portion 24C that is continuous with the inner covering portion 24B and forms an inclined surface 20, and an outer peripheral covering portion 24D that covers the outer periphery of the mounting main body portion 16.

[0012] The shielding portion 14 is provided inside the mounting projection 18 . The shielding portion 14 is composed of an outer fiber-reinforced resin layer 26 located on the underwater side and having an outer surface continuous with the outer surface of the underwater structure 2, an inner fiber-reinforced resin layer 28 located on the sonar room 6 side, at least one intermediate fiber-reinforced resin layer 30 provided between the outer fiber-reinforced resin layer 26 and the inner fiber-reinforced resin layer 28, and a plurality of elastic material layers 32 provided between the outer fiber-reinforced resin layer 26, the inner fiber-reinforced resin layer 28, and the intermediate fiber-reinforced resin layer 30. In this embodiment, one intermediate fiber reinforced resin layer 30 is provided. In addition, the multiple elastic material layers 32 are composed of two layers: a first elastic material layer 32A provided between the outer fiber-reinforced resin layer 26 and the intermediate fiber-reinforced resin layer 30, and a second elastic material layer 32B provided between the inner fiber-reinforced resin layer 28 and the intermediate fiber-reinforced resin layer 30. The outer fiber reinforced resin layer 26 is provided integrally with the outer covering portion 24A, and the inner fiber reinforced resin layer 28 and the middle fiber reinforced resin layer 30 are provided integrally with the gradient covering portion 24C. As the material for forming each of the fiber-reinforced resin layers 26, 28, 30, a fiber-reinforced resin material having a higher strength than the material for forming the elastic material layer 32 can be used, that is, various conventionally known fiber-reinforced resin materials using fibers such as glass fiber, carbon fiber, and aramid fiber as a reinforcing material and a thermosetting resin as a matrix material. The elastic material layer 32 can be made of various conventionally known elastic materials such as viscoelastic materials such as rubber and polyurethane.

[0013] Next, the attachment of the acoustic window 10A to the underwater structure 2 will be described. A plurality of acoustic windows 10A sufficient to close the opening of the sonar room 6 are prepared in advance. The acoustic window 10A has an outer fiber-reinforced resin layer 26 positioned on the underwater side and an inner fiber-reinforced resin layer 28 positioned on the sonar chamber 6 side, and the longitudinal direction of the acoustic window 10A is aligned with the longitudinal direction of the opening of the sonar chamber 6, so that the opening is blocked by the acoustic window 10A. Then, as shown in FIG. 1, the mounting body 16 constituting the upper and lower two sides of the mounting part 12 is attached to the underwater structure side mounting parts 4 at the top and bottom of the opening via fastening members such as bolts B. In addition, the portions of the mounting body 16 located at both ends of the longitudinal direction of the opening of the sonar room 6 are attached to the underwater structure side mounting part 4 via fairing plates (not shown) and fastening members such as bolts. Furthermore, adjacent portions of the mounting body 16 in the longitudinal direction of the opening of the sonar chamber 6 are integrally attached to a fairing plate (not shown) via fastening members such as bolts.

[0014] Next, the effects of the acoustic window 10A of this embodiment will be described. In this embodiment, the inner surface of the mounting protrusion 18 located on the sonar room 6 side is formed with an inclined surface 20 that gradually slopes in the direction of making the thickness of the mounting protrusion 18 thinner as it approaches the shielding portion 14.Therefore, at the boundary between the inclined surface 20 of the inner surface of the mounting protrusion 18 located on the sonar room 6 side and the inner surface of the shielding portion 14, the cross-sectional shape of the acoustic window 10A does not change abruptly as in the prior art, but rather the cross-sectional shape of the acoustic window 10A changes gradually. Therefore, when a load from underwater is applied to the shielding portion 14, this is advantageous in suppressing stress concentration at the boundary between the inclined surface 20 on the inner surface of the mounting protrusion 18 and the inner surface of the shielding portion 14, and is advantageous in improving the durability of the acoustic window 10A. In addition, by providing an inclined surface 20 on the inner surface of the mounting protrusion 18 located on the sonar chamber 6 side, the space occupied by the mounting protrusion 18 within the sonar chamber 6 can be reduced, which is advantageous in terms of ensuring the volume of the sonar chamber 6. In addition, the mounting portion 12 is composed of a frame-shaped metal member 22 that spans the mounting main body 16 and the mounting protrusion 18, and a fiber-reinforced resin covering portion 24 that covers the metal member 22, which is advantageous in increasing the strength of the mounting portion 12 and improving the durability of the acoustic window 10A.

[0015] Furthermore, in this embodiment, the shielding portion 14 is composed of an outer fiber-reinforced resin layer 26 located on the underwater side, an inner fiber-reinforced resin layer 28 located on the sonar room 6 side, one intermediate fiber-reinforced resin layer 30 provided between the outer fiber-reinforced resin layer 26 and the inner fiber-reinforced resin layer 28, and first and second elastic material layers 32A, 32B provided between the outer fiber-reinforced resin layer 26, the inner fiber-reinforced resin layer 28, and the intermediate fiber-reinforced resin layer 30. This is advantageous in improving the durability of the acoustic window 10A by ensuring the strength of the shielding portion 14 while maintaining the acoustic characteristics of the shielding portion 14. In addition, the covering portion 24 comprises an outer covering portion 24A that constitutes the portion of the mounting body portion 16 located on the underwater side, an inner covering portion 24B that constitutes the portion of the mounting body portion 16 located on the sonar room 6 side, and a sloped covering portion 24C that is continuous with the inner covering portion 24B and forms a sloped surface 20, and the outer fiber-reinforced resin layer 26 is formed integrally with the outer covering portion 24A, and the inner fiber-reinforced resin layer 28 and the intermediate fiber-reinforced resin layer 30 are formed integrally with the sloped covering portion 24C, thereby improving the attachment strength of the shielding portion 14 to the mounting portion 12 and thereby improving the durability of the acoustic window 10A.

[0016] (Second embodiment) Next, an acoustic window 10B according to a second embodiment will be described with reference to FIGS. In the following embodiments, parts and members similar to those in the first embodiment are denoted by the same reference numerals, and the description thereof will be omitted, and the description will focus on the differences. The second embodiment is a modified example of the first embodiment, and differs from the first embodiment in that a frame-shaped acoustic member 34 made of an elastic material is arranged in place of the metal member 22 provided on the mounting protrusion 18 along the entire length of the inner periphery of the metal member 22. As the elastic material, a conventionally known viscoelastic material such as rubber or polyurethane, or a fiber reinforced resin material similar to that of the outer fiber reinforced resin layer 26, the inner fiber reinforced resin layer 28, and the middle fiber reinforced resin layer 30 can be used.

[0017] According to the second embodiment, a frame-shaped acoustic member 34 made of an elastic material is arranged in place of the metal member 22 provided on the mounting protrusion 18 along the entire length of the inner periphery of the metal member 22. This is advantageous in that when a load from underwater is applied to the shielding portion 14, the stress generated at the boundary between the inclined surface 20 on the inner surface of the mounting protrusion 18 and the inner surface of the shielding portion 14 can be dispersed by the frame-shaped acoustic member 34 made of an elastic material. At the same time, using the metal member 22 for the mounting protrusion 18 excluding the acoustic member 34 is advantageous in ensuring the strength of the mounting portion 12, which is more advantageous in improving the durability of the acoustic window 10B.

[0018] Furthermore, when the sonar device housed in the sonar chamber 6 emits sound waves through the shielding portion 14 toward an underwater object, if part of the sound waves is reflected or interfered with by the mounting protrusion 18 made of the metal member 22, there is a concern that the reflected or interfered sound waves will be received by the sonar device as noise, which will reduce the detection performance of the sonar device. In particular, as the performance of sonar devices improves and the frequency band of sound waves used becomes higher, the degree to which sound waves are reflected and interfered with by metal materials increases, and there is a significant tendency for detection performance to decrease due to noise caused by the reflection and interference of sound waves. In the second embodiment, a portion of the sound waves emitted from the sonar device is absorbed by the acoustic member 34 arranged along the entire length of the inner periphery of the metal member 22 provided on the mounting protrusion 18, which is advantageous in suppressing the reflection and interference of sound waves and in improving the detection performance of the sonar device.

[0019] Furthermore, if vibrations generated in the underwater structure 2 are transmitted to the shielding portion 14, the vibrations will cause the shielding portion 14 to resonate, generating sound waves that will be received by the sonar device as noise, which could reduce the detection performance of the sonar device. In this embodiment, vibrations generated in the underwater structure 2 are absorbed and mitigated by the acoustic member 34 arranged along the entire length of the inner periphery of the metal member 22 provided on the mounting protrusion 18, which is advantageous in suppressing sound waves generated by resonance of the shielding portion 14 and in improving the detection performance of the sonar device.

[0020] The hardness of the acoustic member 34 is preferably JIS K 6253 Type A 72 degrees or more and 82 degrees or less. Setting the hardness of the acoustic member 34 to be JIS K 6253 Type A 72 degrees or more and 82 degrees or less is advantageous in terms of improving the durability of the acoustic window 10A, ensuring that the acoustic member 34 absorbs some of the sound waves emitted from the sonar device, and ensuring that the vibrations of the underwater structure 2 are absorbed and damped. If the hardness of the acoustic member 34 is less than JIS K 6253 Type A 72 degrees, the required vulcanization reaction is unlikely to occur during manufacturing, the effect of ensuring the strength of the acoustic member 34 is reduced, and the effect of improving the durability of the acoustic window 10A is reduced. If the hardness of the acoustic member 34 exceeds JIS K 6253 Type A 82 degrees, the effect of the acoustic member 34 absorbing part of the sound waves emitted from the sonar device and the effect of absorbing and damping the vibrations of the underwater structure 2 will be reduced. [Explanation of symbols]

[0021] 2 Underwater structure 4. Underwater structure side mounting part 6. Sonar Room 10A, 10B Acoustic windows 12 Mounting part 14 Shielding part 16 Mounting body 18 Mounting protrusion 20 Slope 22 Metal parts 24 Covering part 24A Outer covering part 24B Inner coating 24C Slanted covering section 24D outer sheathing 26 Outer fiber reinforced resin layer 28 Inner fiber reinforced resin layer 30 Intermediate fiber reinforced resin layer 32 Elastic material layer 32A First Elastic Material Layer 32B Second elastic material layer 34 Acoustic components

Claims

1. An acoustic window comprising: a frame-shaped mounting portion attached to a mounting portion on an underwater structure side around an opening of a sonar chamber provided in the underwater structure; and a plate-shaped shielding portion having acoustic transparency and provided inside the mounting portion to close the opening, the mounting portion includes a frame-shaped mounting main body portion attached to the underwater structure side mounting portion, and a frame-shaped mounting protrusion portion protruding toward the opening from a location along the entire length of an inner periphery of the mounting main body portion, and the shielding portion is provided inside the mounting protrusion portion, an inner surface of the mounting protrusion located on the sonar chamber side is formed as an inclined surface that is inclined in a direction in which the thickness of the mounting protrusion becomes gradually thinner as it approaches the shielding portion, The mounting portion is configured to include a frame-shaped metal member provided across the mounting main body portion and the mounting protrusion portion, and a fiber-reinforced resin covering portion that covers the metal member. An acoustic window characterized by:

2. a frame-shaped acoustic member made of an elastic material is disposed in place of the metal member on the mounting protrusion along the entire length of the inner periphery of the metal member; 2. The acoustic window according to claim 1.

3. The hardness of the acoustic member is JIS K 6253 Type A 72 degrees or more and 82 degrees or less.

3. The acoustic window according to claim 2.

4. the shielding portion includes an outer fiber-reinforced resin layer located on the underwater side, an inner fiber-reinforced resin layer located on the sonar chamber side, at least one intermediate fiber-reinforced resin layer provided between the outer fiber-reinforced resin layer and the inner fiber-reinforced resin layer, and a plurality of elastic material layers provided between the outer fiber-reinforced resin layer, the inner fiber-reinforced resin layer, and the intermediate fiber-reinforced resin layer, the covering portion includes an outer covering portion located underwater, an inner covering portion that forms a portion of the attachment main body that is located on the sonar chamber side, and an inclined covering portion that is continuous with the inner covering portion and forms the inclined surface, the outer fiber-reinforced resin layer is integrally formed with the outer covering portion, The inner fiber reinforced resin layer and the intermediate fiber reinforced resin layer are integrally formed with the gradient covering portion.

2. The acoustic window according to claim 1.

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