RU2167496C1 - Hydroacoustic multi-unit antenna and piezoelectric rod transducer for said antenna - Google Patents

Abstract

FIELD: underwater acoustics, applicable in designing and development of hydroacoustic equipment, for sounding of sea bottom and exploration of ocean shelf. SUBSTANCE: antenna has a body filled with electroinsulating liquid, with piezoelectric rod transducers mechanically linked with a common cover plate placed in the body, a shield positioned on the rear side of the antenna. The piezoelectric rod transducers are provided with two passive cup-shaped cover plates. The clearance between the wall edges of the front and rear cup-shaped cover plates facing each front and rear cup-shaped cover plates facing each other makes up a quarter of the wavelength in the electroinsulating liquid at the antenna resonance frequency. Flexible collars of polymeric material are put on the external lateral surfaces of the cup-shaped cover plates as in interference fit. The piezoelectric rod transducer for the antenna has a piezoelectric reinforced member with front and rear cover plates. The rear cover plate is also cut-shaped, the front cover plate is made in the form of a cup. The edges of both cover plates face each other, narrow through slots are made in the cover plate walls over their entire length, they are positioned in circumference of the cross-section of the cover plates, with an irregular interval, and filled with polymeric material with a force fit. Flexible collars of polymeric material are put on lateral surfaces of the cup-shaped cover plates as in interference fit. EFFECT: no distortions caused by undesirable resonances of the oscillatory system, reduced antenna dimensions. 2 cl, 2 dwg

Description

 The invention relates to the field of hydroacoustics and can be used in the design and development of hydroacoustic equipment for sensing the seabed and studying the ocean shelf.

 When developing hydroacoustic equipment, an important place is occupied by the issue of minimizing the dimensions of the created devices while ensuring the high quality of their performance, which should not depend on the influence of external pressure from the environment. For this purpose, the device case is usually filled with an insulating liquid, which is why it is necessary to take into account the effect of filling the device with liquid on its performance [1].

 Currently, compact hydroacoustic antenna designs are known with general sealing of the piezoelectric transducers included in them, installed inside the housing on a common patch on the front of the antenna [2]. Such antennas are used mainly in the range of ultrasonic vibrations. Closest to the technical nature of the claimed invention is the antenna design described in [1] -cm. p. 99, fig. 6.2, a.

 The hydroacoustic multi-element antenna prototype contains a housing filled with an insulating fluid, piezoelectric rod transducers mechanically mounted inside the housing on a common patch on the front of the antenna, and a metal screen on its back located inside the housing. The advantages of the prototype antenna include the simplicity and compactness of the design with high efficiency.

 Its disadvantage is that such a design can be used only at high frequencies, and when you switch to the low sound frequency range, the dimensions and weight of the device increase very quickly.

 The prototype antenna compares favorably with the corresponding analogue [2] in that its design already provides for filling the body cavity with an insulating liquid, which is a sign of closer correspondence to its real structures of the created equipment. At the same time, it also has a drawback that degrades the frequency characteristics of devices and limits the possibility of their use in broadband devices: individual sections of the internal cavity of the prototype antenna filled with liquid — in particular, the liquid channels between adjacent transducers — antenna elements can be excited at their own resonant frequencies, which can lead to distortion of the frequency characteristics of the antenna.

 Also known are the designs of rod transducers in which front and rear passive pads are used to reduce the longitudinal size [1,3]. The closest in technical essence to the proposed one is the design of the piezoelectric rod transducer described in [1] - see page 98, Fig. 6.1 a.

 The prototype piezoelectric rod transducer contains a piezoelectric element clamped by a metal reinforcing pin between two passive plates, of which one - the back - has a glass-like shape, with the edges of the glass wall facing the front radiating plate. The advantages of this converter are that its design is compact and efficient in terms of the achieved antenna parameters.

 The disadvantage of the prototype converter design is the possibility of exciting the glass-shaped wall of the plate at its own resonant frequency of oscillations - the so-called bell effect, which usually leads to distortion of the frequency response of the converter. In addition, the possibility of reducing the longitudinal size of the transducer is not fully utilized in this design.

 The objective of the invention is to provide a multi-element sonar antenna with reduced dimensions in the direction normal to the surface of the aperture, and with a frequency response that does not have distortion caused by undesirable resonances of the oscillatory system.

 To solve this problem, a multi-element hydroacoustic antenna containing a housing filled with an insulating liquid with piezoelectric rod transducers placed in it mechanically connected to a common patch and a screen located on the back of the antenna have introduced new features, namely, rod transducers are equipped with two passive cup-shaped overlays, and the gap between the edges of the walls of the front and back cup-shaped overlays facing each other zovatelya is a quarter wavelength in the insulating liquid at the resonant frequency of the antenna, and the outer side surface of the cup-linings are coated with a polymeric material.

 The piezoelectric rod transducer for a multi-element antenna contains a piezoelectric reinforced element, while the back plate has a glass-like shape and mechanical contact with the piezoelectric element on the bottom surface of its inner cavity.

 New in the inventive converter is that the front overlay of the converter is also made in the form of a glass and the edges of the walls of both glass-shaped plates are facing each other, while along the entire height of the walls of the glass-shaped plates there are narrow longitudinal through slots located around the circumference of the cross section of the walls of the plates with uneven step and filled with a tight fit with polymeric material, and on the outer side surfaces of the glass-shaped plates with an interference fit, elastic cuffs made of polymer material Methods and material.

 The use of glass-shaped pads can significantly reduce the height of the transducers, therefore, the height of the antenna - its size in the direction perpendicular to the surface of the aperture. In this case, the gap between the edges of the walls of the plates equal to a quarter of the wavelength in the insulating liquid at the operating frequency ensures the absence of direct acoustic coupling between the plates and prevents the occurrence of spurious resonances in the volume of the insulating liquid filling the cavity of the antenna body, while coating the outer side surfaces of the plates with polymer material prevents the propagation of sound waves in the space between the transducers, as in channels with acoustically soft walls kami, which also prevents the appearance of additional resonances in the frequency response of the antenna. Thus, the proposed design measures make it possible to improve the frequency characteristics of the antenna and reduce its dimensions.

 The presence of slits in the walls of the glass-shaped plates made with an uneven pitch around the circumference of the wall cross-section allows almost completely to avoid the occurrence of undesirable intrinsic resonances of the walls of the plates. At the same time, the tight filling of the slots with polymeric material and the tight-fitting polymer cuffs attenuate these spurious oscillations that occur when there are slits, but with a lower amplitude. Thus, the proposed design makes it possible to eliminate unwanted resonances of the oscillatory systems of the transducer and antenna, as well as reduce their geometric dimensions.

 The invention is illustrated in FIG. 1, which shows the proposed design of a multi-element antenna, and FIG. 2, which shows the construction of a piezoelectric rod transducer for this antenna.

 A multi-element antenna (Fig. 1) contains a housing 1 filled with an insulating liquid, the front part of which 2, which is separated from the external environment by a matching device 3, is a common overlay for a group of piezoelectric rod transducers 4 with glass-shaped overlays 5, on the side surfaces of which are fitted with an interference fit of the cuff 6 from polymeric material; a screen 7 is mounted on the back surface of the housing 1.

 The piezoelectric rod transducer (figure 2) contains a piezoelectric element 8 and a reinforcing pin 9, tightening the glass-shaped lining 5 with a polymer coating on their side surface in the form of an elastic cuff 6, worn on them with an interference fit. Figure 2 also shows a cross-section of a piezoelectric rod transducer (view in AA), which shows the section of the walls of the glass-shaped plates - slots 10, filled with a tight fit with polymeric material - in this example, rubber, which in combination with rubber cuffs 6, worn with an interference fit on the lateral surfaces of the plates, it provides effective suppression of unwanted resonance phenomena in the oscillatory systems of the transducer and antenna.

 The operation of the claimed device is a hydroacoustic multi-element antenna with piezoelectric rod transducers is as follows. On the piezoelectric elements of the transducers, mounted on a common plate, the electrical voltage of the signal, which is necessary to excite mechanical vibrations that emit sound waves from the radiating surface of the antenna into the environment, is supplied through the electrical leads. When the antenna is in the reception mode, a signal is recorded at its electrical terminals that appears during forced mechanical vibrations due to the action of sound waves incident on the surface of the antenna’s common lining.

 Both during operation of the antenna in the radiation mode and in the reception mode, the insulating liquid also participates in the oscillation process due to the fact that it is in acoustic contact with different parts of the oscillating system, and thanks to the proposed structural measures that weaken this connection, it is possible to almost completely suppress the unwanted resonance phenomena in the volume of liquid in the body cavity and eliminate their influence on the frequency response of the antenna. At the same time, during mechanical longitudinal vibrations of the piezoelectric rod transducers that are part of the antenna, unwanted spurious resonances can also occur in the working frequency band of the antenna due to the influence of transverse vibrations of the walls of the glass-shaped plates, which can be reduced as a result of the technical solutions proposed in this application or generally excluded.

Literature
1. Underwater electro-acoustic transducers. (Calculation and design): Reference book / V.V. Bogorodsky, L.A. Zubarev, E.A. Korepin, V.I. Yakushev. - L., Shipbuilding, 1983.- 248 p.

 2. Pat. Japanese application 5-11710. Underwater Broadband Transceiver. IPC H 04 R 1/44, 17/00, G 01 H 3U / 0. Publ. 02.16.93.

 3. Pat. U.S. 3.974.474. Underwater electro-acoustic transducer with overlay developed inward. Publ. 08/10/76.

Claims (2)

 1. A hydroacoustic multi-element antenna, comprising a housing filled with electrical insulating fluid and placed on it with piezoelectric rod transducers mechanically connected to a common patch, and a screen located on the back of the antenna, characterized in that the piezoelectric rod transducers are equipped with two passive glass-shaped pads and a gap between facing each other the edges of the walls of the front and back cup-shaped plates is a quarter of the wavelength in oizolyatsionnoy fluid at the resonant frequency of the antenna, and the outer side surface of cup-worn linings with interference elastic cuff of a polymeric material.  2. A piezoelectric rod transducer for a multi-element sonar antenna containing a piezoelectric reinforced element with front and back plates, the back plate having a glass-like shape, characterized in that the front plate is also made in the form of a glass and the edges of the walls of both glass-shaped plates are facing each other, when this in the walls of the glass-shaped plates over their entire height made narrow through-slots located around the circumference of the cross section of the walls of the plates with unequal polar step and filled with press fit polymeric material, and on the side surfaces cup-worn linings with interference elastic cuffs polymeric mater.

Images