JPS5846711B2 - Dopra sonar - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention utilizes the Doppler effect of underwater ultrasound to provide ground-to-water,
It also relates to a transmitter/receiver that has a vibrator such as a piezoelectric element that converts electricity to sound and sound to electricity, which is a component of an objective speedometer. It was designed to provide an actual device that can automatically correct the effects of sound speed caused by seawater temperature, salinity, fluid fluctuations, etc., and approximate the principle of automatic sound speed correction. In a transducer that measures velocity based on the Doppler effect that occurs between received sound waves, a plurality of inclined surfaces are used, the surface in contact with water has a planar shape, and the surface opposite to water contact is inclined in the same direction at the same angle. A sound wave transmitting material is provided, and a backing material is attached to each of the inclined surfaces of the sound wave transmitting material, and the directionality is such that the sound wave transmitting material can cover a wide range in both wing directions along a hyperbola considered to be on the sea floor, which is the basis of the Doppler spectrum. This relates to a transmitting/receiving device for Doppler sonar, etc., characterized in that it is equipped with a transducer unit in which a plurality of swept-whiff-shaped transducers are arranged so that the length in the traveling direction is longer than the width. It is.

To explain the conventional transmitting and receiving device with reference to FIG. 1, 1 is the bottom of the ship, 2 is a wave transmitting/receiving oscillator, 3 is a pickup for measuring water temperature,
4 is an air vent pipe, and since this conventional transmitting/receiving device has a recess a, air bubbles traveling along the bottom of the ship accumulate in the recess a and interfere with the ultrasonic waves, making it necessary to measure the water temperature in order to correct the speed of sound. It had the disadvantage of requiring salinity correction.

In order to eliminate the drawbacks caused by the recess a of this device,
It is also possible to install an acoustically transparent material 5 in the recess a as shown in Fig. 2 so that the plane for transmitting and receiving sound waves is flush with the bottom 1 of the ship, thereby preventing air pockets from forming and interfering with the ultrasonic waves. However, since sound speed correction is not automatically performed, a pickup for measuring water temperature is still required.

Furthermore, in order to avoid problems such as interference caused by air pockets, sound velocity correction, and salinity correction, some types of transducers are kept at an equal temperature by immersing the transducer in oil in a pocket that is flat when viewed from the outside. There was a drawback that an isothermal maintenance mechanism had to be provided.

Conventional transducer units were one-element type and did not constitute an array transducer, so they could not automatically correct the sound speed, and air pockets were generated, which had a large effect on air bubbles traveling through the bottom of the ship. It was difficult to obtain sufficient performance, and piezoelectric vibrators were shaped like disks, squares, or rectangles, but these have the property of widening the shape of the receiving spectrum, which causes detection errors. There was a problem.

The present invention eliminates such drawbacks. First, the principle of automatic sound speed correction will be explained with reference to FIG. ft toward the seabed 8, and if the frequencies of the received signals in the front and rear directions are frl and fr2, respectively, there is the following relationship.

Here C is the speed of sound in water. FIG. 4 is a cross-sectional view of a piezoelectric vibrator 9 that vibrates in the direction of the arrow, which is the thickness direction, and is the same as the single piezoelectric vibrator used conventionally. As shown in FIG. 5, by arranging the transducers io and 1i which transmit and receive waves at an angle θ in the front direction and the transducers 12 and 13 which transmit and receive waves at an angle θ in the rear direction, the following can be achieved.

Here α is a constant.

A feature of equation (2) is that the speed υ of the ship depends only on frtfr2 and nothing else.

Next, the principle will be explained with reference to FIG.

If the distance between the transducers is D, then when the wavelength of the underwater ultrasound in the θ direction is an integral multiple of D cos θ, the ultrasound in the θ direction strengthens each other, creating the following relationship.

Here, n is an integer and λ is the underwater ultrasound wavelength.

It is.

Here, n can be calculated as follows. The size of the vibrator is determined, θ is determined from the wave transmission and reception direction, and the underwater wavelength (average) λ is given.

Next, from equation (3), n(1, 2, 3,...
) can be found as a table.

From the size of the vibrator determined earlier, select n and D that match the actual arrangement.

To explain in more detail, when the sound speed C in water changes due to temperature, salinity, etc., the underwater ultrasonic wavelength changes, and the equation (
Although the angle θ that satisfies the condition of 3) changes, the constant α in equation (4) does not depend on the speed of sound C in water, so equation (4) does not change.
Therefore, the constant α remains unchanged.

Vibrator 10, 11°12.
13 at a distance that satisfies Equation (3) and connects them in parallel. If this is used for Doppler sonar transmission and reception, changes in underwater sound speed can be avoided. It is possible to configure independent transmitting and receiving devices.

This is the principle of automatic sound speed correction.

In principle, it is sufficient to have two oscillators in one direction as shown in Fig. 5, but it is also possible to have three oscillators in one group as shown in Fig. 7A, or as shown in Fig. 7. A plurality of oscillators may be arranged in a group of four oscillators as shown in B.

The Doppler sonar transmitter/receiver, which does not depend on the underwater sound speed, is constructed by arranging the transducers to satisfy equation (3) and electrically connecting them in parallel.
Examples of the arrangement of the vibrators are shown in FIG. 5, FIG. 7A, and FIG. 7B.

By utilizing the above-mentioned principle, it can be applied in exactly the same way to a speedometer for a vehicle using aerial ultrasonic waves, or a speed detection device for a railway vehicle, an automobile, etc. that is installed on the ground.

In this case, C is only the propagation speed of sound in the air, and the rest is exactly the same as in the case of a ship.

The above principle is a theoretical principle when the oscillation source is a point and the spectrum is a line, but in practice it is not valid in principle when the oscillation source has no directivity like a point. do not have.

For this reason, it is often considered to make the vibrator in a planar shape in order to give the oscillation spectrum directivity, but even if the vibrator is made in a planar shape, there is a problem that an error occurs due to the broadening of the spectrum width, which deviates from the above-mentioned principle.

The present invention provides a specific configuration for solving such problems, which will be explained in detail below.

FIG. 8 shows the structure of the transmitter/receiver housing that supports the transducer unit according to the present invention. Reference numeral 15 denotes a housing integrally made of cast metal or resin. The bottom reinforcing ring 14 is attached by welding, and the housing 15 is fixed with stud bolts 22 and nuts with waterproof asbestos 16 interposed on the top surface of the bottom reinforcing ring 14.

Vibrator unit mounting holes 25, 25 are formed in the lower surface of the housing 15 for mounting a vibrator unit shown in FIGS. 9 and 10, which will be described later.

Reference numeral 23 denotes an electric wire hole through which the cable of the transducer unit is passed. The cable passed through the electric wire hole 23 is connected to the terminal block 18 through the electric wire penetration metal fitting 17, and from the terminal block 18, another electric wire is connected to the electric wire penetration metal fitting. Go outside through 19.

The space in which the terminal block 18 is installed is covered with a top cover 20 with waterproof asbestos 16 in between, and is tightly tightened with through bolts and nuts 21.

An upper lid hanging fitting 24 for holding the upper lid 20 by hand is attached to the upper surface of the upper lid 20.

Next, the transducer unit in the transmitter/receiver of the present invention is installed in the transducer unit mounting hole 25 as shown in FIG.
Figure 0 will be explained.

A sound wave transmitting material 28 is provided which has a plurality of inclined surfaces whose water contact side (surface in contact with seawater) is a flat surface and whose anti-water contact side (surface on the ship's side) is inclined in the same direction at the same angle. 2
The oscillators 26 and 27 each have a surface shape on each of the inclined surfaces of 8 and are formed so as to reduce the width of the Doppler shift spectrum.
will be established.

A back material 29.30 such as cork or balsa wood is attached to the back surface of the vibrator 26.27.
30 together with the coating material 31 and 32 of the sound wave transmitting material 28
The lead wire 62 is led out.

The inclination angle and distance of the vibrators 26 and 27 are determined according to equation (3).

A small housing 34 made of cast iron or resin for these
and glue the flange surfaces together.

The cable 64 passes through the wire through fitting 35 and passes through the housing 3.
4, the boundary between the lead wire 62 and the cable 64 is designed to prevent leakage of the pressure-resistant fluid 33 due to incompressible fluid such as oil.
Adhesive hardening 63 is applied.

The pressure-resistant liquid 33 is filled from the inlet of the plug 36 to seal it.

In order to pass the cable 64 through the housing 34, it is convenient to provide a groove at one location as shown in FIG.

The housing 34 of the vibrator unit thus made is placed in the eighth
It is inserted from below into the vibrator unit mounting hole 25 of the housing 15 shown in the figure, and is attached by screwing the holding bolt 38 into the surrounding mounting hole together with the holding ring 37 (see FIG. 9).

Flat transducer unit mounting marks 50, 51, 52, and 53 are attached to the housing 15 in order to properly fit the transducer unit, and transmitter/receiver mounting marks 54.5 are provided to ensure that the housing 15 is correctly mounted on the bottom 1.
5 is also attached to the housing 15.

In FIG. 9, reference numeral 49 indicates an 01J groove into which an O-ring is fitted in order to maintain watertightness, and watertightness within the housing 15 is achieved by the O-ring fitted into the 0-ring groove 49, the wire penetration fittings 17 and 19, and the waterproof asbestos 16. I keep it.

The transmitting/receiving device assembled in this way does not have the air vent pipe 4 (see Fig. 1) like the conventional one, and the storage space for the terminal block 18 is integrated into the housing 15 along with the mounting hole 25 for incorporating the flat transducer unit. This makes it possible to reduce the number of system configuration units, and by welding the bottom reinforcing ring 14 instead of welding the main pipe as in the past, all that is left to do is assembly, making the transducer replacement work easier than before. It has the following features.

In addition, the transducer unit has directional characteristics for transmitting and receiving ultrasonic waves in diagonal directions from a flat surface, enables automatic sound velocity correction, prevents the transducer from peeling off the adhesive, is compact, easy to handle, and can withstand high pressure. be.

Next, the shape of the vibrator will be explained.

Figures 11 and 12 show the shape of a transducer that allows the received Doppler shift spectrum width to be small, that is, the amplitude to be large relative to the spectrum width.
By arranging multiple oscillators, the hyperbola 4 considered on the sea floor, which is the basis of the Doppler shift spectrum in Figure 14, is arranged.
Swept wing that has a wide directional area 48 in the direction of both wings along the 4.45
It is shaped like an airplane wing.

FIG. 11 is a perspective view of the vibrator 39 attached to the sound wave transmitting material 40, and FIG. 12 is a plan view of the arrangement of the vibrator 39, and 41 and 42 are outlines of the vibrator.

If the oscillator were not shaped like the one shown in Figures 11 and 12, but instead a oscillator was cut into multiple pieces and had a circular shape as a whole, it would be possible to create a circular oscillator on the ocean floor. The directional ellipse 47 (Fig. 13) is a hyperbola 44.4 considered to be on the sea floor, which is the basis of the Doppler shift spectrum.
5 in the width direction is small, and therefore, as is clear from the curve 43 showing the relationship between frequency and amplitude in FIG. 13, its height is low relative to the width of the spectrum, resulting in This results in a problem in that the Doppler shift spectrum width becomes wide and digital counting errors in the Doppler shift frequency are likely to occur.

In contrast, by arranging the suede vibrators shown in FIG. 11 as shown in FIGS. 7A and B and FIG.
As shown in Figure 4, a directional area 48 that covers a wide area in both wing directions between hyperbolas 44 and 45 that can be considered on the ocean floor.
It can be done.

That is, compared to the case where the vibrator is divided into a plurality of pieces and has a circular shape as a whole as shown in the comparative example, the 11th
By arranging a plurality of swept wing-shaped vibrators 39 in the traveling direction of the ship as shown in FIGS. 7A and B and FIG. It is formed to be longer than the diameter and shorter than the diameter in the width direction.

Then, as is clear from FIGS. 13 and 14, the directional area assumed on the seabed is shorter in the direction of travel than the directional ellipse 47 expected on the seafloor due to the circular vibrator. , resulting in a long directional region 48 in the width direction.

Therefore, as shown by curve 43', the height can be increased relative to the spectral width, resulting in a narrower Doppler shift spectral width, which reduces the digital count error of the Doppler shift frequency and allows the automatic sound velocity correction to be performed. You can get closer to the principle.

As is clear from the above, if the directional area has the same width as f1 (width in the direction of the center line 46 in Fig. 13.14) or the directional area has the same area, the circular oscillator shown in Fig. 13 In some cases, a swept wing-shaped vibrator as shown in FIG. 11.12 can significantly narrow the Doppler shift spectrum width.

Note that the number of vibrators is not limited to two vibrators arranged in an array as shown in FIG. 12, but may be any number as long as it is two or more.

Figures 15 and 16 focus only on the vibrator, and are drawn to conceptually understand the arrangement and size seen from above. In Figure 15, two vibrators 56 and 57 are arranged. FIG. 16 shows an arrangement in which four vibrators 58, 59 and 60, 61 are arranged.

In order for the sound wave transmitting material 28 shown in FIG. 9 to withstand high pressure and to prevent the center from being dented by the pressure, the inner lower surface of the housing 34 and the center upper surface of the sound wave transmitting material 28 are provided with reflection and absorption of sound waves as shown in FIG. 17. It is preferable to bond the material 65 and the pillar 66.

The sound wave reflection/absorption material 65 is made of cork, balsa wood, etc.
The pillar 66 blocks the propagation of sound waves from the housing 34.
This prevents noise from being directly transmitted to the

The pillar 66 is preferably molded from metal, resin, or the like.

FIG. 18 shows a state in which a sound wave reflection/absorption material 65 is attached to the inner surface of the housing 34 to prevent noise from propagating from the housing 34 to the vibrator 26, 27 (see FIG. 9) via the pressure-resistant liquid 33. FIG.

FIG. 19 shows that the vibrator 27 in FIG. 9 is coated with a coating material together with the backing material 30 so that the vibrator 27 in FIG. 18 is a cross-sectional view showing a state covered with a noise barrier. When making a vibrator that can withstand noise, it is especially important to use it in conjunction with the soundproof wall shown in FIG. 18.

In FIG. 20, the sound wave transmitting material 28 and the housing 34 are firmly adhered to each other so that the pressure-resistant liquid 33 (see FIG. 9) does not come out from inside. The housing 34 is firmly attached and bonded, and the retaining ring 37 is attached with a bolt passed through the mounting hole 38.
At the same time, the sound wave transmitting material 28 and the housing 34 are tightly integrated.

As described above, in the present invention, the anti-oscillator mounting surface (water-contacting surface) of the sound-transmitting material has a planar shape, which prevents air pockets from forming, and therefore eliminates the need for air vent piping when installing the transmitter/receiver. This makes ant control easier than before, and by effectively arranging the transducers, it is possible to create constants between velocity and Doppler shift frequency that are independent of sound velocity, such as water temperature and salinity, so a heating and isothermal holding machine is installed. The sound speed can be automatically corrected even if the ship is not equipped, and the installation work such as welding the bottom reinforcement ring is easy, and since the terminal block is integrated with the transducer, the number of system configuration units can be reduced and the system can be improved. It can be easily made, withstands high pressure underwater, and prevents the bonded vibrator from peeling off.
Furthermore, by forming the transducer so that the width of the received Doppler shift spectrum can be narrowed, it is possible to reduce errors when the oscillation source is made into a planar shape to provide directivity, and to approach the principle of automatic sound velocity correction. It has excellent effects.

[Brief explanation of the drawing]

Figure 1 is a longitudinal cross-sectional view of a conventional Doppler sonar transducer, Figure 2 is a cross-sectional view of the acoustically transparent material attached to the conventional Doppler sonar transducer, and Figure 3 is a diagram explaining the principle of automatic sound velocity correction. Figure 4 is a cross-sectional view of a piezoelectric vibrator, Figure 5 is an explanatory diagram of the arrangement of vibrators, Figure 6 is an explanatory diagram of the principle of an arrayed vibrator, and Figure 7A is an explanatory diagram of an arrayed vibrator with three vibrators. , FIG. 7B is an explanatory diagram of an arrayed transducer made up of four transducers, FIG. 8 is a vertical cross-sectional view of an embodiment of the transmitter/receiver housing according to the present invention, and FIG. 9 is an illustration of an array of transducers according to the present invention. A longitudinal cross-sectional view of the embodiment,
Fig. 10 is a plan view of Fig. 9, Fig. 11 is a perspective view showing the shape of the transducer, Fig. 12 is a plan view of the array transducer, and Fig. 13 is the received wave spectrum by the transducer with a circular surface. Explanatory diagram,
Fig. 14 is an explanatory diagram of the reception spectrum by the array transducer in Fig. 12, Fig. 15 and Fig. 16 are arrangement diagrams of the transducer,
Figure 7 is a sectional view of the pillar, Figure 18 is a sectional view of the soundproof wall, Figure 19 is a sectional view of the main part of a vibrator unit designed to prevent noise, and Figure 20 is a sectional view of the main part of the vibrator mounting part. It is. 10.11, 12, 13, 26, 27, 39°56.5
7, 58, 59, 60, 61... vibrator, D.
...Distance of the vibrator, θ...Angle.

Claims (1)

[Claims] 1. In a transducer that measures velocity based on the Doppler effect that occurs between transmitted and received sound waves, there are multiple transducers whose water-contacting surfaces have a planar shape and whose anti-water-contacting surfaces are inclined at the same angle in the same direction. A sound wave transmitting material having an inclined surface of Transmission/reception in Doppler sonar, etc., characterized by having a transducer unit in which a plurality of swept-whiff-shaped transducers are arranged so that the length in the traveling direction is longer than the width so as to have a directional area that can be covered. Device.