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JPH08175490

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This translation is machine-generated. It cannot be guaranteed that it is intelligible, accurate,
complete, reliable or fit for specific purposes. Critical decisions, such as commercially relevant or
financial decisions, should not be based on machine-translation output.
DESCRIPTION JPH08175490
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an
underwater vehicle traveling in water, and reduces the propagation of vibrations generated
inside the underwater vehicle to the wave receiver, such as an engine unit for propulsion. Related
to the underwater vehicle.
[0002]
2. Description of the Related Art An underwater vehicle traveling in water generally comprises a
wave receiver for receiving and converting an acoustic wave propagating in water into an electric
signal. The wave receiver is used as a receiver of a sonar for detecting an obstacle present in the
traveling direction of the underwater vehicle and investigating the shape of the seabed.
[0003]
FIG. 4 shows the appearance of a conventionally used underwater vehicle. The underwater
vehicle 101 includes a bullet-like main body. A propulsion engine 102 is disposed on the rear
end side of the main body. Underwater can be navigated by rotating the screw 103 by the engine
102 for propulsion. A wave receiver 104 is embedded in the outer peripheral portion of the main
body to receive sound waves.
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1
[0004]
FIG. 5 shows a cross-sectional structure of a substantially central portion of the underwater
vehicle shown in FIG. Since the wave receiving portion 104 present at substantially the center of
the underwater vehicle is cylindrical, the cross-sectional structure shown in FIG. 5 is vertically
symmetrical. For this reason, in order to simplify the illustration, each part is given a code only
for the upper side of the figure.
[0005]
The substantially central portion of the underwater vehicle has a cylindrical shape and is made of
a metal material such as aluminum alloy of a predetermined thickness. The cylindrical portion
has a short diameter over a predetermined length in the longitudinal direction of the underwater
vehicle at a substantially central portion thereof, and forms a short diameter portion 112. The
recessed portion of the short diameter portion 112 is filled with the mold resin 113, and the
wave receiving element 114 is embedded in this. Further, on the outer periphery of the
cylindrical metal portion of the short diameter portion 112, a sound insulating material 115 is
disposed at a position facing the wave receiving element 114. The sound insulation member 115
functions to reduce the propagation of the vibration from the engine 102 shown in FIG. 1 to the
wave receiving element 114. In addition, the sound insulating material 115 also has an effect as
a backing material that reflects the sound wave to be received to improve the sensitivity of the
wave receiving element.
[0006]
The mechanical impedance of the mold resin 113 of the underwater vehicle is such that there is
no large difference from that of the main body 111 in order to withstand the water pressure.
Therefore, the vibration from the engine 102 is transmitted through the mold resin 113 and
propagated to the wave receiving element 114, and even if the sound insulating material 115 is
provided, the effect of reducing the vibration is relatively small. The vibration from the main unit
111 causes noise to the sound wave to be received, and degrades the signal-to-noise ratio at the
output of the wave receiving element 114. Therefore, various proposals have been made to
reduce the propagation of vibration from the engine 102 to the wave receiving element 114.
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[0007]
In Japanese Utility Model Application Laid-Open Nos. 3-40194 and 60-109065, there is an
underwater running body in which a vibration blocking material is interposed between a main
body provided with a vibration source such as an engine part and a wave receiver. It is disclosed.
Further, Japanese Utility Model Application Laid-Open No. 63-7886 discloses an underwater
vehicle in which propagation of vibration is suppressed by surrounding and fixing a wave
receiving portion with a polymer foam material. In addition, a wave receiving part may be
provided inside the head of the main body, and in Japanese Utility Model Laid-Open Publication
No. 62-44287, a damping material is provided inside the head housing the wave receiving part.
An underwater vehicle is disclosed.
[0008]
JP-A-64-16980 discloses an underwater vehicle in which a pressure-resistant shell of the head is
formed of a high damping material such as FRP (fiber reinforced plastic). By forming a pressureresistant shell with a high impedance material, the propagation of vibration to the wave receiver
housed inside is reduced. Further, in this underwater vehicle, the acoustic rubber layer
supporting the wave receiving element is covered up to the outer peripheral surface of the
pressure-resistant shell so that the boundary between the pressure-resistant shell and the
acoustic rubber is far from the wave receiving element. By securing a sufficient distance between
the boundary and the wave receiving element, the propagation of noise due to turbulence
generated at the boundary during navigation to the wave receiving element is reduced.
[0009]
Furthermore, in Japanese Patent Laid-Open No. 2-304385, there is provided an underwater
vehicle in which a tuned absorber having the same resonant frequency as the receiver is
provided around the receiver so that the propagating vibration is absorbed thereby. Is disclosed.
Japanese Patent Application Laid-Open No. 57-168595 discloses an underwater vehicle in which
a wave receiving element is disposed in a closed space filled with a liquid such as oil. The
enclosed space is formed by the acoustic rubber to which the wave receiving element is attached
and the shell of the main body and the back plate, and the liquid filled therein suppresses the
propagation of vibration to the wave receiving element.
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[0010]
In these conventional underwater vehicles, the vibration transmission to the wave receiving
element is reduced by providing the vibration blocking material and the vibration proof rubber.
However, the effect of the vibration reduction by the vibration blocking material or the vibrationproof rubber is limited to a specific vibration mode or a specific frequency range, and the
vibration reduction effect can not be obtained over a wide frequency band. Therefore, when it is
desired to receive a sound wave propagating from water in a wide frequency range, there is a
problem that a frequency band in which the signal-to-noise ratio is deteriorated is generated in
the band due to the vibration of an engine or the like.
[0011]
Even when a tuned absorber is provided or when a pressure-resistant shell is formed of a high
impedance material such as FRP, the propagation of vibration is reduced over a wide band as in
the case of a vibration-shielding material or a vibration-proof rubber. The same problem occurs.
Moreover, in order to obtain the effect of vibration reduction, the vibration blocking material and
the vibration proof rubber have low mechanical impedance, and the hardness is not so high. For
this reason, if the water depth becomes large, it will be crushed and deformed by the depth
pressure. For example, when the sound insulation member 115 shown in FIG. 5 is formed of a
rubber with a closed cell, there is a problem that the usable depth of the underwater vehicle is
limited to several tens of meters.
[0012]
When the wave receiving element is disposed in a closed space filled with a liquid such as oil as
in JP-A-57-168595, the mechanical impedance between the main body portion formed of an
aluminum alloy or the like and the liquid The ratio is large, and vibration can be reduced over a
wide band. However, since water pressure is applied only from one side of the enclosed space, it
is difficult to maintain the enclosed space under high water pressure, and there is a problem that
the usable depth of the underwater vehicle can not be increased.
[0013]
Therefore, a first object of the present invention is to provide an underwater vehicle that can
reduce the propagation of vibration from an engine to a wave receiver over a wide frequency
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band.
[0014]
A second object of the present invention is to increase the usable depth of the underwater
vehicle.
[0015]
According to the first aspect of the present invention, a main body having a substantially
cylindrical shape as a whole and having a substantially central portion shorter than a portion
adjacent in the axial direction over a predetermined distance. A wave receiving portion which is a
cylindrical member disposed so as to cover the short diameter portion of the main body portion
and having an inner circumferential surface slightly larger than the outer circumferential surface,
and in which a wave receiving element for receiving vibration is embedded; The underwater
vehicle is equipped with a magnet disposed at a position facing the short diameter portion of the
main body portion and the wave receiving portion so as to keep a gap between them by the
repulsive force of each other.
[0016]
That is, according to the first aspect of the present invention, the propagation of vibration from
the main body to the wave receiving portion is reduced by maintaining a gap between the wave
receiving portion and the main body portion by the repulsive force of the magnet.
Also, in water, the gap formed by the repulsive force of the magnet is filled with water.
Since the mechanical impedance ratio between the water and the main body is large, the
propagation of vibration can be reduced in a wide frequency band.
In addition, since the receiving portion receives the same water pressure from the inside and the
outside by filling the gap with water, it is difficult for deformation or destruction due to water
pressure to occur.
[0017]
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In the invention according to claim 2, the wave receiving portion has a cylindrical shape, and the
outer peripheral portion of the main body portion adjacent to both ends of the wave receiving
portion has a circular shape having substantially the same diameter as the outer peripheral
portion of the wave receiving portion. The outer periphery of the diameter portion is slightly
shorter than the inner peripheral portion of the wave receiving portion.
[0018]
That is, according to the second aspect of the present invention, the wave receiving portion has a
cylindrical shape, and the outer peripheral portion of the main body portion adjacent to both
ends of the wave receiving portion has substantially the same diameter as the outer peripheral
portion of the wave receiving portion. There is.
As a result, the difference in level between the wave receiving portion and the outer peripheral
portion of the main body portion is reduced, and turbulence generated during navigation is
reduced, and it is difficult for the wave receiving portion to receive vibrations resulting
therefrom.
[0019]
In addition, since a gap is formed between the inner peripheral portion of the wave receiving
portion and the outer peripheral portion of the short diameter portion of the main body due to
repulsion of the magnet, the propagation of vibration from the main body to the wave receiving
portion is reduced. . Furthermore, since the wave receiving portion has a cylindrical shape, its
strength is strong against water pressure, and the usable depth can be increased.
[0020]
In the invention according to claim 3, a propulsion engine is disposed in the main body, and the
wave receiving element is an element for detecting a sound wave propagating in water.
[0021]
That is, in the invention according to the third aspect, the vibration of the propulsion engine
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disposed in the main body is difficult to propagate to the wave receiving element for detecting
the sound wave propagating in the water by the gap formed by the repulsive force of the magnet.
.
Therefore, the signal to noise ratio of the signal output from the wave receiving element can be
improved.
[0022]
In the invention according to the fourth aspect, the annular members for airtightness are
respectively sandwiched between the both end portions of the wave receiving portion and the
main body portion opposed thereto.
[0023]
That is, according to the fourth aspect of the present invention, water is prevented from entering
the water into the gap formed by the repulsive force of the magnet by holding the air-tight
annular member.
The mechanical impedance between the air filled in the air-tight gap and the body portion is
larger than that with the water, so vibration propagation can be reduced more effectively in a
wide frequency band.
[0024]
In the invention according to claim 5, the annular member uses an O-ring as an elastic member
having a large mechanical impedance ratio.
[0025]
That is, in the invention according to the fifth aspect, since the annular member for air tightness
uses the O-ring as an elastic member having a large mechanical impedance ratio, the propagation
of the vibration from the main body to the wave receiver is small. It can be suppressed.
[0026]
The present invention will be described in detail by way of the following examples.
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[0027]
FIG. 1 shows a cross section of a wave receiving portion of an underwater vehicle according to an
embodiment of the present invention and the periphery thereof, which substantially corresponds
to FIG.
Since the wave receiving part 15 which exists in the approximate center part of the underwater
vehicle has a cylindrical shape, the sectional structure shown in FIG. 5 is vertically symmetrical.
For this reason, in order to simplify the illustration, each part is given a code only for the upper
side of the figure.
Also, the overall shape of the underwater vehicle is similar to that of the conventional one shown
in FIG.
[0028]
The main body has a structure in which a main body rear portion 11 accommodating an engine
(see FIG. 4) and a main body head 12 at the tip end side are detachably joined, and the joint
surface is watertightly coupled by an O-ring 13 and a bolt 14 It has become so. The main body
head 12 is formed of a metal material such as an aluminum alloy having a predetermined
thickness, and the main body rear portion 11 side has a shorter diameter than its periphery over
a predetermined length.
[0029]
Further, the rear portion 11 of the body is also formed of a metal material such as an aluminum
alloy having a predetermined thickness. Therefore, when the rear body portion 11 and the main
body head 12 are connected by the bolt 14, the concave short diameter portion 15 is formed in a
cross-sectional shape in the substantially central portion of the underwater vehicle.
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[0030]
A cylindrical wave receiving portion 16 is disposed in the short diameter portion 15 so as to
cover the short diameter portion 15. The inner diameter of the wave receiver 16 is slightly larger
than the outer diameter of the short diameter portion 15. Further, the outer diameter of the wave
receiving portion 16 is equal to the diameter of the outer peripheral portion of the rear portion
11 adjacent to the short diameter portion of the short diameter portion 15. The wave receiver 16
is fitted into the above-mentioned short diameter portion before connecting the rear portion 11
and the head portion 12 with the O-ring 13 and the bolt 14.
[0031]
Permanent magnets 18 and 19 of the same polarity (for example, the S pole) are embedded in
the short diameter portion 15 of the rear portion 11 of the main body and the portions of the
wave receiving portion 16 facing each other. A gap 17 of a predetermined distance is provided
between the wave receiving portion 16 and the short diameter portion 15 by the repulsive force
of the permanent magnets 18 and 19 so that the wave receiving portion 16 and the body
portions 11 and 12 do not contact with each other. It has become.
[0032]
The wave receiving portion 16 is provided with a cylindrical support portion 21 having flanged
shapes at both ends. Urethane resin 22 is filled between the two flanges of the support portion
21 so as to match the height of the flanges. A wave receiving element 23 is embedded in the
urethane resin 22. The lead wire 24 of the wave receiving element 23 is led to a circuit portion
(not shown) of the rear portion 11 of the main body through the watertight connector 25. The
support portion 21 and the main body portions 11 and 12 are each formed of an aluminum
alloy.
[0033]
The sound waves coming from the water vibrate the wave receiving element 23 through the
urethane resin 22. The wave receiving element 23 is formed of a ceramic piezoelectric element,
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and outputs an electric signal according to the vibration when it receives vibration. Other than
this, a piezo element or a piezoelectric rubber can be used as the wave receiving element 23.
[0034]
FIG. 2 is a cutaway of the wave receiver of the underwater vehicle shown in FIG. 1 in the
direction perpendicular to the central axis. Permanent magnets 18 are disposed on the main
body 12 at predetermined intervals in the circumferential direction. Permanent magnets 19 of
the same polarity are disposed on the inner peripheral surface of the support portion 21 at
positions facing the magnets 18, and a gap 17 is formed by the repulsive force between them.
The wave receiving element 23 is disposed inside the urethane resin 22. The underwater vehicle
receives sound waves coming from an angle within a predetermined range, and the wave
receiving element 23 is provided only in the portion corresponding to the range.
[0035]
When the underwater vehicle having the above configuration is disposed in water, the water fills
the gap 17 shown in FIG. Water in the gap 17 becomes a mechanical impedance barrier.
Therefore, the propagation of the vibration generated by the engine 102 to the wave receiver 16
can be significantly reduced. Further, the mechanical impedance ratio between water and the
aluminum alloy constituting the main body head 12 or the main body rear portion 11 is large,
and the propagation of vibration can be reduced over a wide frequency band. As a result, it is
possible to widen the good frequency band of the signal to noise ratio.
[0036]
In addition, when the water fills the gap 17, the wave receiver 16 receives the same water
pressure from the inner peripheral side and the outer peripheral side. For this reason, even if the
water pressure is high, the effect is cancelled, and the repulsive force of the permanent magnets
18 and 19 holds the gap 17. As a result, the underwater vehicle can be used up to high depth
pressure, and navigation to deeper places is possible.
[0037]
Modified example
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[0038]
FIG. 3 shows a cross section of the wave receiving portion of the underwater vehicle according to
a modification of the present invention.
The same parts as those in FIG. 1 are denoted by the same reference numerals, and the
description thereof will be appropriately omitted. In the underwater vehicle of this modification,
an O (O) ring 31 is disposed at a position where the support portion 21 of the wave receiver 16
and the main body portions 11 and 12 of the underwater vehicle face each other. The O-ring 31
is formed of a rubber-based material, and the space between the main body portion and the wave
receiving portion is sealed to prevent water from entering the gap 17.
[0039]
Therefore, when the underwater vehicle of this modification is placed in water, the gap 17 is
filled with the air layer. Further, since the mechanical impedance of the O-ring 31 is substantially
equal to that of water, vibration is less likely to propagate from the main body to the wave
receiver 16 via the O-ring 31. The permanent magnet 18 is provided on the outer peripheral
portion of the main body portion in the short diameter portion 15 and on the inner peripheral
portion of the support portion 21 so that the gap 17 is formed by the repulsive force thereof. It is
similar.
[0040]
In this modification, the mechanical impedance ratio between the air present in the gap 17 and
the aluminum alloy constituting the main portions 11, 12 is larger than that with water.
Therefore, the propagation of vibration can be reduced more effectively by holding the air layer.
[0041]
Further, in this modification, since the gap 17 is filled with air, the water pressure acts only from
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the outer peripheral side of the wave receiving portion 16. However, since the support portion
21 is made of an aluminum alloy having a predetermined thickness, the water receiving portion
16 is not deformed by water pressure. Furthermore, since the shape of the wave receiving
portion 16 is a cylindrical shape capable of obtaining high strength against water pressure, the
navigable depth of the underwater vehicle can be increased.
[0042]
Further, a uniform water pressure is applied to the cylindrical wave receiving portion 16 from all
directions of the outer peripheral surface thereof. Such an even water pressure cancels any
biasing force, and the wave receiver 16 is disposed concentrically with the main body 11, 12.
Therefore, the repulsive force of the permanent magnet 18 only needs to have a size sufficient to
form the gap 17 against gravity regardless of the water pressure.
[0043]
Furthermore, in the modification, the mechanical impedance of the air in the hermetically sealed
gap 17 is largely different from those of the support portion 21 of the aluminum alloy and the
urethane resin 22, so the effect of reflecting the sound wave at the boundary is large. For this
reason, the air in the gap 17 has an effect as a backing material, and also plays a role of
improving the reception sensitivity of the wave receiver.
[0044]
In addition, by providing a rubber shock absorbing material thinner than the gap 17 on the
opposing surfaces of the wave receiving portion 16 and the main body, the gap 17 may be
crushed by sudden acceleration at the start or stop, or the support portion It is possible to
prevent contact destruction between the body 21 and the body parts 11 and 12. Also, if the gap
17 is filled in advance with oil such as castor oil and sealed with a rubber band or the like to
finish the boundary between the wave receiver and the main body more smoothly, the
occurrence of turbulent flow at the boundary is prevented It is possible to reduce the noise
caused by the turbulence generated during navigation.
[0045]
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Although the permanent magnet is used for the underwater vehicle in the embodiment and the
modification, it is also possible to configure this by an electromagnet or a combination of a
permanent magnet and an electromagnet. Moreover, it is natural that the overall arrangement
structure of the underwater vehicle, such as the position of the engine, can be appropriately
changed.
[0046]
As described above, according to the first aspect of the present invention, a gap is formed
between the wave receiving portion and the body portion by the repulsive force of the magnet, so
that the vibration of the body portion is received by the wave receiving portion. Propagation can
be reduced over a wide frequency band. In addition, since the water receiving portion receives
the same water pressure from the inside and the outside when water enters the gap in water, it is
difficult for deformation and breakage to occur, and the usable depth can be increased.
[0047]
Further, according to the invention of claim 2, the wave receiving portion is cylindrical, and the
diameter of the outer peripheral portion of the main body portion adjacent to the both ends is
almost equal to the outer peripheral portion of the wave receiving portion. There is less
turbulence inside and less noise due to turbulence received at the receiver. In addition, since a
gap is formed between the inner peripheral portion of the wave receiving portion and the outer
peripheral portion of the short diameter portion of the main body due to repulsion of the magnet,
the propagation of vibration from the main body to the wave receiving portion is reduced.
Furthermore, since the wave receiver has a cylindrical shape, its strength against water pressure
is high, and the usable depth can be increased.
[0048]
Further, according to the third aspect of the present invention, it is difficult for the vibration of
the propulsion engine disposed in the main body to propagate to the wave receiving element for
detecting the sound wave propagating in the water by the gap formed by the repulsive force of
the magnet. ing. Therefore, deterioration of the signal-to-noise ratio due to engine vibration can
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be reduced.
[0049]
Further, according to the invention of claim 4, since the gap formed by the repulsive force of the
magnet is hermetically sealed by the annular member, the air layer is held in the gap even in
water, and the propagation of vibration is reduced more effectively in a wide frequency band. can
do.
[0050]
Furthermore, according to the invention of claim 5, since the annular member for air tightness
uses the O-ring as an elastic member having a large mechanical impedance ratio, the propagation
of the vibration from the main body to the wave receiver is possible. Can be reduced.
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