JP2961993B2 - Ultrasonic transducer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic transducer for transmitting and receiving in deep water.

[0002]

2. Description of the Related Art Among the conventional ultrasonic transducers, as shown in FIG. 4, a flex tensional transducer 30 disclosed in U.S. Pat. There is. The transducer 30 comprises an elliptical shell 31, an active column 32 laminated in the longitudinal direction of the elliptical shell 31, and an end piece 33 connecting both ends of the active column 32 and the inner wall of the elliptical shell 31. Have been. In the operation of the transducer 30, the longitudinal vibration of the active columnar body 32 is transmitted to the elliptical shell 31 via the end piece 33, and the elliptical shell 31 bends and vibrates, so that sound waves are radiated into water. Here, since the piezoelectric ceramic or the magnetostrictive material constituting the active column 32 is weak against tensile stress, a compressive force is applied to the vibrator in advance to cancel the tensile stress acting on the vibrator during excitation.

[0003]

[SUMMARY OF THE INVENTION However, as shown in FIG. 4, if the applied hydrostatic pressure F ₀ in the elliptical shell 31, acting tension F ₁₀ in the long axis direction of the elliptical shell 31 from the nature of the elliptical shape As a result, it acts as a tensile stress on the active column 32 through the end piece 33. Therefore,
In deep water, when the transducer is driven, mechanical destruction of the vibrator may occur if the sum of the hydrostatic pressure on the vibrator and the excitation tension exceeds the limit of the vibrator's tensile stress. there were.

The present invention has been made in view of the above problems, and has as its object to provide an ultrasonic transducer which does not apply a tensile stress to a vibrator even in deep water.

[0005]

In order to achieve the above object, the present invention relates to an ultrasonic transducer having an active columnar body disposed in an elliptical shell. Both open ends are accommodated so as to face the short-side wall of the elliptical shell, and a first side wall of the inner shell that does not hold the active columnar body is connected to the long-side wall of the elliptical shell. The second side wall for holding the columnar body is arranged in the axial direction of the elliptical shell. Further, in the present invention according to claim 2, the inner shell has a cylindrical shape having an octagonal cross section,
The active columnar body is made of a piezoelectric ceramic or a magnetostrictive vibrator.

[0006]

In the present invention according to the first aspect of the present invention, even if tension is applied in the longitudinal direction of the elliptical shell by hydrostatic pressure, a compressive force is applied to the active column by the inner shell. Further, the vibration amplitude is double amplified by the bending motion of the inner shell and the elliptical shell. Further, in the present invention according to the second aspect, the inner shell having an octagonal cross section acts on the active columnar body of the piezoelectric ceramic or the magnetostrictive vibrator by using the tension in the major axis direction of the elliptical shell as a compressive force. Let it.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. In FIG. 1, reference numeral 1 denotes an elliptical shell having an elliptical cylindrical shape, and upper and lower open ends are sealed by a watertight cover (not shown).

Reference numeral 2 denotes a cylindrical inner shell having an octagonal cross section, which is housed in an elliptical shell 1. The inner shell 2 has its open end directed toward the short-axis side wall 1a of the elliptical shell 1 and a first side wall 2a that does not hold an active columnar body 3 described later is connected to the long-axis side wall 1b of the elliptical shell 1.
And the second holding the active column 3
The side wall 2b is located in an axial direction perpendicular to the major axis direction of the elliptical shell 1. Also, on the upper surface of the inner shell 2,
Reference numeral 5 denotes a prestress bolt for applying a compressive force to the active columnar body 3 in advance, and reference numeral 6 denotes a through hole for use in positioning the inner shell 2 and attaching a watertight cover (not shown).

Reference numeral 3 denotes an active column formed by laminating a piezoelectric ceramic or a magnetostrictive vibrator, and the stacking direction of the column is aligned with the opening end direction which is the axial direction of the elliptical shell 1. It is located between them. Reference numeral 7 denotes an electrode of each piezoelectric ceramic or the like, 8 denotes a lead wire for supplying an AC electric signal to the active columnar body 3, and 9 denotes a spring electrode for conducting each piezoelectric ceramic or the like.

Next, the operation of this embodiment will be described.
First, when an AC electric signal is input to the active columnar body 3, longitudinal vibration is excited. The vibration amplitude generated from the active columnar body 3 is transmitted to the inner shell 2 contacting both ends, amplified by the bending motion of the inner shell 2, and further transmitted to the elliptical shell 1 via the end piece 4. And
Also in the elliptical shell 1, the vibration amplitude is amplified again by the bending motion, and a large amplitude is obtained.

Further, as shown in FIG. 2, when the hydrostatic pressure F ₀ acts on the elliptical shell 1 in deep water, the elliptical shell 1 extends in its long axis direction, and the first side wall 2a of the inner shell 2 is in contact with the elliptical shell 1. It acts as a tension F _{1 on} the contact surface with the end piece 4. This tension F ₁ is, as shown in FIG. 3, a compression force F ₂ for compressing the second side wall 2 b of the inner shell 2 up and down.
Acts on the active columnar body 3. Accordingly, even in deep water, the tension does not act on the active columnar body 3 due to the hydrostatic pressure, but acts as a compressive force.
Mechanical destruction is prevented.

In the above embodiment, the sectional shape of the inner shell 2 is octagonal. However, if the sectional shape is such that a tension is applied in one direction and a compressive force acts in a direction perpendicular to the direction, Other common shapes other than octagons, for example, ellipses, can be used.

[0013]

As described above, according to the first aspect of the present invention, the provision of the cylindrical inner shell between the elliptical shell and the active columnar body acts on the elliptical shell in the major axis direction by hydrostatic pressure. Since the tension is applied to the active column as a compressive force, the active column is not mechanically broken by the tensile stress even in deep water. In addition, since the inner shell and the elliptical shell have a double bending motion,
The vibration amplitude is significantly amplified. According to the second aspect of the present invention, the tension in the major axis direction of the elliptical shell effectively acts as a compressive force on the active columnar body such as a piezoelectric ceramic by the inner shell having an octagonal cross section.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an ultrasonic transducer according to the present embodiment.

FIG. 2 is a plan view illustrating the action of the above force.

FIG. 3 is a cross-sectional view for explaining the action of the same force.

FIG. 4 is a plan view showing the action and configuration of force in a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Oval shell 1a Short side wall 1b Long side wall 2 Inner shell 3 Active columnar body 4 End piece

Claims (2)

(57) [Claims] In an ultrasonic transducer having an active columnar body disposed in an elliptical shell, a cylindrical inner shell is disposed in the elliptical shell and both open ends thereof are directed to the short-axis side wall of the elliptical shell. And a first side wall that does not hold the active columnar body of the inner shell is connected to a longitudinal side wall of the elliptical shell, and a second side wall that holds the active columnar body is an axial center of the elliptical shell. An ultrasonic transmitter / receiver characterized by being arranged in a direction. 2. The ultrasonic transducer according to claim 1, wherein the inner shell has a cylindrical shape with an octagonal cross section, and the active columnar body is made of a piezoelectric ceramic or a magnetostrictive vibrator.