KR830001121B1 - Directional transducer - Google Patents

Abstract

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Description

Directional transducer

1 is an axial longitudinal view of a directional converter according to the invention.

2 is a cross-sectional view of the converter of FIG.

The present invention relates to a directional transducer, in particular wherein first and second bending disc transducer members are mounted at respective axial ends of the cylindrical housing, the transducer members being an electrical signal resulting from acoustic signals axially incident on the transducer. And a transducer electrically connected together to reinforce the electrical signals resulting from acoustic signals incident in a direction perpendicular to the axis of the cylindrical housing.

According to the prior art, this type of transducer has a bending disc transducer member with each end mounted directly on the housing. The center of the bending disc is mechanically bound to an inertial body retained in the housing, and when the acoustic wave incident in the axial direction collides, the housing vibrates against the inertial body causing bending of the disc transducers, thereby generating an electrical output signal. Let's do it.

It is an object of the present invention to provide a directional transducer of the type which is more robust in structure, has a higher impact resistance, can be easily assembled, and is preferably prestressed in a predetermined amount after assembly of the transducer.

According to the invention, the first and second deflection converting members each comprising a circumferential plate-shaped member are fixed at circumferentially opposite inertia ends generally perpendicular to the axis. A force transmission device, such as a coupling bolt, connects the central portion of each of the planar members with the housing that surrounds the inertial-bending transducer assembly along the axis of the inertial body. A device for connecting transducer elements to an electrical signal detection device is provided. In a preferred embodiment, the housing is made of plastic and is cylindrically shaped to have a cylindrical inner space.

The inertial body is provided with a circular cavity at each axial end, which is closed by disc transducer members whose outer edges are fixed to the axial ends of the inertial body. Disc transducer members are thin double plate assemblies of metal spring materials and piezoelectric materials. The axial inner surfaces of each of the flexure discs in the cavity include a disc formed of a joining material. The axial outer surfaces of the bending disc transducer members are connected to adjacent axial ends of the cylindrical housing by force transfer rods. A conductive member is provided to connect the transducer members facing each other in series and to connect the members to the electrical signal detection device.

A high viscosity fluid will be provided in the housing, and a device for mitigating vibration of the bending disc will also be provided, thereby improving the broadband response of the transducer.

In a preferred embodiment, the force transfer rods are arranged to stretch the bending disc in the outer axial direction, thereby providing a compressive force to the piezoelectric member as well as providing an external electrical connection.

The transducer has a major advantage which is structurally more convenient than this type of conventional transducer. In the prior art, it was necessary to connect the centers of the bending disc members to the inertia and then to assemble the inertia in a housing that was sealed around the bending disc. In contrast, in the present invention, the assembly is facilitated by pre-assembly of all members bound to the inertia and post-assembly in the housing and by binding the bending discs to the housing by the central rods in the final state. Static field adjustments to these rods are performed after assembly.

This type of assembly provides not only mechanical convenience, but also the conductors can be easily preassembled to the transducer element when the transducer elements are assembled to the inertia, and then through the housing when the inner assembly is assembled into the outer plastic housing. Because it can be withdrawn, it is more convenient from an electrical point of view.

1 and 2 show a direction changer 10 according to the invention. The converter 10 comprises an external housing 12 made of a plastic material such as polycarbonate having the tradename EXAN or MACROLON. In the plastic housing 12 there is provided an inertial body 14 which is slightly smaller than the size of the inner cavity in the housing 12. The housing 12 and the inertia 14 have a cylindrical shape and have an axis of symmetry 15. Inertial body 14 is typically made of a material having a relatively high mass compared to housing 12 and is preferably made of tungsten silicide, lead, or brass. Inertial body 14 is located in the center of the housing and bound to housing 12. At each of the axial ends of the inertial body 1.4, cylindrical plastic rings 16 and 18 are provided. Each of the rings is wrapped by flexural discs 20,22, preferably made of brass having a thickness of 1/4 mm, so that the entire assembly 16, 18, 20, 22 is attached to inertia 14.

Bending discs 20, 22 are mounted on each ring 16, 18, the circumference of which is supported by an inertial body 14. Also the centers of each of the discs are bound to the housing 12. Thus, in contrast to the conventional arrangement of the transducer of this type, the perimeter of the bending disc transducer members is bound to the inertial body, not the housing, and the center to the housing, not the inertial body. This special arrangement allows for a more convenient assembly to be described and also enables prestressing of the transducer elements.

Each bending disc 20,22 is provided with a disc transducer member 24, 26 mounted on an axial inner surface. The transducer parts 24 and 26 are made of piezoceramic and are provided with conductor coatings on the axial and outer surfaces.

Therefore, these discs act as transducers and convert the mechanical stresses caused by the vibrations of the flexure discs 20,22 into electrical signals.

Ceramic discs 24 and 26 were mounted on brass bending discs 20 and 22 using conductive epoxy. The discs 24, 26 have a thickness roughly the same as the brass discs, but have a slightly smaller diameter to fit within the cavities 28,30 formed by closing the rings 16, 18 by the discs 20,22. Although the cavities 28 and 30 contain air only, the space 32 between the inertia 14 and the housing 12 is filled with a high viscosity fluid having a viscosity of 3000 centistokes through the filling hole 54, followed by plug 52 The filling hole 54 is sealed by this.

Highly viscous fluids tend to mitigate the vibration of inertial body 14 relative to housing 12. The space between each of the flexure disks 20, 22 and the adjacent inner surfaces of the housing 12 can be adjusted to adjust the damping of the vibration of the transducer. The high viscosity of the fluid promotes this relaxation. The unit may be completely filled or partially filled to be occupied by bubbles 33 in the remaining space.

By adjusting the size of the bubble, the relaxation can be adjusted to maintain the same relaxation even when the gap size changes due to manufacturing tolerances. Such a conventional transducer design allows this vibration dampening to coordinate wideband transducer operation and suppress undesirable vibration resonances of the flexural disc structure.

According to the invention, the bending discs 20,22 are bound to the housing 12 along the transducer shaft 15 by engaging studs 34,36.

Studs 34 and 36 are firmly bound to flexure disks 20 and 22, for example by welding or brazing, and helixed to nuts 38 and 40 to provide an adjustable bond. Thus, by adjusting the studs 34 and 36, bending prestressing outward of the discs 20 and 22 can be provided to cause initial pressure stress on the ceramic discs 24 and 26.

Compression prestressing of ceramic discs 24 and 26 is required to adjust the zero representation of the transducer characteristic curve. It is also desirable to prestress the ceramic in the compression direction so that the ceramic is not subjected to severe impact. The ceramic transducer members 24, 26 are electrically connected so that the acoustic disturbances occurring in the transducer in the axial direction face each other in order to cause the generation of the reinforcement voltage from the two transducer members 24, 26.

In the illustrated embodiment, the conductors 42, 44 are connected to the inner surfaces of the discs 26 and 24, respectively, and are connected to each other via inertia 14, while the outer surfaces of the discs 24 and 26 are connected to the terminals 46,48 via studs 34,36. Is connected to.

Nuts 38 and 40 and studs 34 and 36 are sealed by a suitable sealant 50.

Preferably, the ceramic discs 24, 26 are made of piezoelectric material such as lead zirconate titanate.

Suitable materials designated G1512 are obtained from Gulton Industries.

The actual transducer as shown in FIGS. 1 and 2 is almost equal to 2 1/2 cm in length with the total diameter slightly over 1/2 cm.

The flexural brass discs 20,22 and the ceramic discs 24,26 have a diameter chosen to be accommodated in the housing 12 and have a thickness of about 0.25 mm, as shown. Housing 12 is typically made by casting plastic and may be made of several parts that are joined together at assembly using a suitable epoxy. Since the reversible theorem is applied to the transducer, the effectively mentioned "hydrophone" will be used as a transmitter of acoustic waves having the same directional characteristics as in the reception mode.

When acting as a transmitter, compression prestressing of the ceramic discs 24, 26 allows the drive signal to be higher than the unstressed discs. Various modifications may be made within the scope of the invention.

Claims (1)

A directional transducer having at least one flexural disc transducer member mechanically interconnected to an inertial body and a housing, the directional transducer comprising a flexural disc 20, 22 of thin metal and a flexural transducer member 24, 26 of piezoelectric ceramic. The transducer members 20, 22, 24 and 26 are bounded in the axial direction of the inertia 14 which is bound to the periphery of the inertia 14 and the center of the housing 12 and is perpendicular to the axis 15 of the housing. Force transmission devices 34,36 having a suitable shape arrangement, which are installed around the ends and are prestressed such that the metal discs 20, 22 are axially stretched so that the ceramic discs 24, 26 are positioned in a compressed state. ) Is installed in the housing (12) along the shaft (15) to mutually bind the centers of the planar transducer members (20, 22, 24, 26).

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