JP2754725B2 - Tuned transducer - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an electroacoustic transducer for use in water, and more particularly to an electroacoustic transducer used at a resonance frequency, and externally adjusting the resonance frequency and the sharpness of resonance, that is, the selectivity. The present invention relates to a tunable transducer.

(Prior art) Conventionally, a mechanical resonance type transducer using a respiratory vibration mode of a cylindrical vibrator as this kind of transducer, or water or seawater as an external medium flows into the cylindrical vibrator, There is a water column resonance type transducer that utilizes the resonance of a water column separated by a cylindrical vibrator.

As shown in FIG. 4 (a), the mechanical resonance type transducer is formed by alternately stacking a cylindrical vibrator, 31a to 31c with a cushioning material, 32a to 32d,
Both ends are supported by lids, 33a and 33b and a shaft 34, and the entire interior of the cylindrical vibrator is covered with a sheath as an air chamber.

As shown in FIG. 4 (b), the cylindrical vibrator is provided with electrodes 38a, 38b on the inner and outer peripheral surfaces of a cylindrical piezoelectric material 37, and a resonance frequency (r ') in the respiratory vibration mode between these electrodes, When the sound velocity of the material is c and the average diameter is 2, r '
When an electric signal having a frequency calculated as = c / 2π is added, a highly efficient sound output can be obtained by mechanical resonance of the cylindrical vibrator.

As shown in FIG. 5 (a), the water column resonance type transducer has a structure in which the inner and outer peripheral surfaces and the end surface of a cylindrical vibrator 41 are covered with a sheath 42, and an external medium flows into the cylindrical vibrator. Such a transducer has a mechanical resonance frequency (r ')
In addition to the above, it has an acoustic resonance frequency (r ″) due to a water column inside the cylindrical vibrator. The water column resonance frequency (r ″) indicates the sound velocity of the medium inside the cylindrical vibrator as Co, the diameter of the inner peripheral surface as 2a _i ,
When the axial length of the inner peripheral surface is 1 and the correction coefficient based on the length-diameter ratio is α, it is calculated by r ″ = Co / 2 (l + 2αa _i ). Highly efficient sound output can be obtained.

[Problems to be solved by the invention]

However, in conventional mechanical resonance type transducers, the resonance frequency is determined by the sound speed and dimensions of the piezoelectric material of the cylindrical resonator, and the water column resonance type transducer is designed and assembled once because the resonance frequency is determined by the dimensions of the cylindrical resonator. In addition, the resonance frequency of the transmitter / receiver cannot be adjusted later, and the efficient frequency band is fixed near the resonance point.

Furthermore, in the water column resonance type transducer, the medium inside the cylindrical vibrator is low-viscosity, low-loss water or seawater, and the acoustic radiation resistance is lower than the mechanical resonance frequency in the respiratory vibration mode of the cylindrical vibrator. As shown in FIG. 5 (b), the selectivity of resonance (r ″) becomes remarkably high, and the resonance frequency becomes unstable due to a change in the sound speed of the medium due to a change in water temperature or water depth. There are drawbacks.

[Means for solving the problem]

The transducer of the present invention has a plurality of cylindrical vibrators, a support member for arranging these vibrators coaxially, an interval adjusting mechanism for adjusting the arrangement interval of these vibrators, A rubber tube that is disposed on the inner surface and contains a high-viscosity liquid inside, and a liquid amount adjustment mechanism that adjusts the amount of the high-viscosity liquid in the rubber tube, and adjusts the interval and liquid amount from outside the transducer. Has the function of adjusting the resonance frequency and the selectivity.

That is, the resonance frequency changes the interval between the plurality of cylindrical vibrators and changes the coupling of the liquid column resonance system between the cylindrical vibrators, so that the total number of cylindrical vibrators can be calculated from the liquid column resonance frequency of one cylindrical vibrator. Is adjusted up to the liquid column resonance frequency when close contact is made. Further, the selectivity is adjusted by adjusting the amount of the high-viscosity liquid in the rubber tube disposed on the inner surface of the cylindrical vibrator.

〔Example〕

Next, the present invention will be described with reference to the drawings. First
1A and 1B are a partial sectional perspective view and a longitudinal sectional view, respectively, of an embodiment of the present invention. Cylindrical vibrators 1a to 1c are supporting plates 2a to 2d
And the support plates 2a to 2d are supported by screws by support rods 3a to 3d. Vibrator 1c is supported
c, 2d and support rods 3c, 3d are attached at the approximate center of the span where the distance can be adjusted, and vibrators 1a and 1b are attached to both ends of vibrator 1c with support plates 2a, 2b and support rods 3a, 3b, respectively. ing.
The support rods 3a and 3b have right-hand screws cut upward from the center and left-hand screws cut downward.They fit into the tap screw holes of the support plates 2a and 2b, and are connected to the gears 4a and 4b at the upper end. , Gear 4
It has a structure that can be rotated from outside by the shaft 5a via c.

A rubber tube 9 is provided inside the cylindrical vibrator over a span whose distance can be adjusted.
20 (for example, high-viscosity silicone oil), and one end of the rubber tube 9 is connected to a pipe 13 and a flange 13 through an oil hole.
The oil chamber 22 is connected. With the high viscosity liquid in the oil chamber, the piston 15 moves up and down in the oil chamber by the rotation of the shaft 5b, thereby increasing or decreasing the amount of liquid in the rubber tube and changing the outer diameter of the rubber tube. Cylindrical oscillators 1a-1c, support plates 2a-2
d, support rods 3a to 3d, gears 4a to 4c and rubber tube 9
a, covered with flange 13 and sheath 21
To prevent attenuation of sound waves directly radiated from the outer peripheral surfaces of the cylindrical vibrators 1a to 1c.

When the shaft 5a is rotated to maximize the interval between the cylindrical vibrators, the arrangement relationship becomes as shown in FIG. 2 (a). At this time, the liquid column resonance frequency inside the cylindrical vibrator is almost equal to the liquid inside the individual cylindrical vibrator. It is equal to the column resonance frequency (r ₁ ) and its value is r ₁
Co / 2 (l ₁ + 2αa _i ), and the bandwidth (Δ ₁ ) as a parameter of the selectivity is as shown by the curve (a) in FIG.

If only the interval between the cylindrical vibrators is minimized, the arrangement relationship becomes as shown in FIG. 2 (b), and the liquid column resonance frequency at this time is the liquid column resonance frequency (r ₃ ) of the inside of the cylindrical vibrator for approximately three liquid columns.
And its value is r ₃ Co / 2 (l ₃ + 2αa _i ), and the bandwidth (Δ ₃ ) becomes narrow as shown by the curve (b) in FIG. The reason why the bandwidth (Δ ₃ ) is narrowed as shown by the curve (b) is that the acoustic radiation resistance is lowered due to the decrease in the resonance frequency, and the interference between the radial mode and the axial mode of the liquid column resonance is reduced. This is because the loss of the resonance system has decreased.

Here, the shaft 5b is rotated, and the oil chamber is
When the high viscosity liquid 19 of 22 is sent out to the rubber tube 9, the second
As a result, the high viscosity liquid inside the cylindrical vibrator increases and the loss of the liquid column resonance system increases. As a result, the bandwidth (Δ ₃ ′) is changed to the curve (c) in FIG. It becomes wide like.

Although the present embodiment has described the case where three cylindrical vibrators are used,
By devising the interval adjusting mechanism, the number can be increased.

Further, in the present embodiment, the case where the transducers having the same dimensions are used has been described, but the dimensions may be different as long as a liquid column resonance system can be formed.

Further, the shaft for adjusting the interval and the liquid amount is drawn out to both end surfaces of the transducer, and the structure is described in which the shaft is manually rotated.
It is also possible to attach torque motors to both ends and control them remotely on board.

〔The invention's effect〕

As described above, the present invention adjusts the resonance frequency and the selectivity by including the cylindrical vibrator, the gap adjusting mechanism of the vibrator array, and the liquid amount adjusting mechanism of the high-viscosity liquid inside the cylindrical vibrator. There is an effect that a so-called tuning type efficient transducer can be realized.

[Brief description of the drawings]

1A and 1B are views showing an embodiment of the present invention, in which FIG. 1A is a partial sectional perspective view, and FIG. 1B is a longitudinal sectional view. FIG. 2 is an arrangement state diagram at the time of adjustment in the embodiment of the present invention. FIG. 3 is a diagram showing a characteristic curve at the time of adjustment in the embodiment of the present invention. FIG. 4 shows a conventional mechanical resonance type transducer.
Is a longitudinal sectional view, (b) is a perspective view of a vibrator, and (c) is a characteristic curve diagram. FIG. 5 is a view showing a conventional water column resonance type transducer, in which (a) is a longitudinal sectional view and (b) is a characteristic curve. 1a, 1b, 1c, 31a, 31b, 31c, 41 ... Cylindrical vibrator, 2a, 2b, 2c, 2d
…… Support plate, 3a, 3b, 3c, 3d …… Support rod, 4a, 4b, 4c …… Gear, 5a, 5b, 34 …… Shaft, 6a, 6b …… Rechainer, 7
a, 7b O-ring, 8a, 8b, 33a, 33b Lid, 9 Rubber tube, 11a, 11b, 11c Band, 12 Pipe, 1
3 …… Flange, 14 …… Oil hole, 15 …… Piston, 17 ……
Filling material, 18,36,43 …… Cable, 19 …… High viscosity liquid,
20 …… Low viscosity liquid, 21,35,42 …… Sheath, 32a, 32b, 32c,
32d …… a cushioning material.

Claims (1)

(57) [Claims] 1. A plurality of cylindrical vibrators, a support member for arranging these vibrators coaxially, a spacing adjusting mechanism for adjusting the spacing between the vibrators, and an inner surface of these vibrators. A tunable transducer comprising a rubber tube arranged and filled with a high-viscosity liquid therein, and a liquid amount adjusting mechanism for adjusting the amount of the high-viscosity liquid in the rubber tube.