EP3266019B1 - Sound transducer for sending and/or for receiving underwater acoustic signals, transducer device, sonar, and watercraft - Google Patents

Description

The invention relates to a sound transducer for transmitting and/or receiving acoustic underwater signals, which has an acoustic transducer element, at least one first spring element, a filling compound and a transducer carrier, the at least one first spring element being assigned to the acoustic transducer element. Furthermore, the invention relates to a converter device, a sonar and a watercraft.

According to the prior art, sound converters for transmitting and/or receiving acoustic underwater signals are designed to be rigid, in particular the acoustic converter element is permanently installed.

DE 10 2009 059902 B3 , DE 38 34 669 A1 , EP 2 200 017 A2 each disclose a sound transducer for transmitting and/or receiving acoustic underwater signals, which has an acoustic transducer element, at least a first spring element, a filling compound and a transducer carrier.

Such a sound transducer is often constructed according to the principle of the clay mushroom. For example, a piezoelectric ceramic is clamped between two rigid plates. The piezoelectric ceramic acts as a spring, which is "set" by an electrical voltage, for example. When the sound transducer is used as a transmitter, a voltage is applied to the piezoelectric ceramic, causing it to move mechanically. The ceramic expands and "vibrates". The vibration is transmitted to the mechanically coupled plates as masses. This will make the Pressure and thus the emitted acoustic signal amplified.

The clay mushroom forms a closed vibration structure made up of two masses (the plates in the example above), which are connected by an “elasticity” (piezoelectric ceramics in the example) as a spring. The masses are designed to be free of elasticity and the elasticity is ideally mass-free. The vibration amplitudes of the two masses fall in the direction of the line connecting the points of elasticity.

In a common embodiment of the clay mushroom as a sound transmitter into a surrounding medium, a stack of piezo rings is prestressed by a bolt between a solid tail and head mass. The tail and head masses lower the resonant frequency below that of the piezo stack. Biasing causes high intensity transmission and delivery. Here, the head mass usually has a lower mass than the tail mass. In addition, the head mass is widened on the side facing away from the piezo stack and has a foam at the widened end in order to achieve better coupling of the sound energy to the low impedance of the surrounding medium (air and/or water).

Due to the fixed arrangement with the bracing of the acoustic transducer element between two rigid masses, such a designed sound transducer is limited to low frequencies and high intensities.

It is therefore practically impossible to freely adjust such a sound transducer in terms of frequency, intensity and sensitivity.

Furthermore, there is the disadvantage that when a sound pressure wave hits it, with a particularly high sound pressure level, a clay mushroom transmits the pressure directly to the following material to a large extent due to its rigidity.

In underwater vehicles, a sonar usually has an acoustic absorber behind the acoustic converter element, which absorber has the task of “swallowing” the sound pressure on the rear side of the acoustic converter element and is therefore sensitive to pressure. Thus, when using a clay mushroom, there is a risk that the acoustic absorber will be destroyed due to the direct transmission with high sound intensity. This disrupts the communication, navigation and/or location on board the underwater vehicle.

As a result, both the sensitivity and the general functionality of sonars on board can be reduced.

The object of the invention is to improve the prior art.

The object is achieved by a sound transducer according to claim 1.

By designing the acoustic transducer element as a mass with an associated spring element, the acoustic effectiveness of the sound transducer is increased.

In addition, an open, elastic oscillating system is set by the acoustic transducer element as a mass, which is elastically connected to the transducer carrier via the first spring element.

Since the acoustic transducer element is designed as the first spring element and, contrary to the configuration as a clay mushroom, is designed without tension, it can oscillate freely and can therefore also be set specifically for higher frequencies and intensities.

The design of the acoustic transducer element in conjunction with the spring element and the transducer carrier can achieve the greatest possible acoustic sensitivity (receiver) and/or the greatest possible transmission factor (transmitter) in a desired frequency range, and set and optimize it in a targeted manner.

Due to the elastic design, an acoustic absorber, which usually follows the wave transducer in a sonar of a watercraft, also remains intact.

An essential idea of the invention is based on the fact that the acoustic transducer element is not designed to be rigidly braced, but rather that the acoustic transducer element is arranged on an elastic spring element and the transducer carrier, which in particular are mechanically capable of oscillating.

Due to the mechanical oscillating ability of the spring element and/or the transducer carrier, there is not only decoupling from the acoustic absorber, which is usually mounted behind the transducer carrier, but also feedback to the acoustic transducer element, so that part of the output variable of the incident sound pressure wave is applied directly or in a modified form to the acoustic Transducer element is returned. As a result, amplification occurs in particular.

Due to the design of the acoustic transducer element as a mass with the associated spring element, the oscillating system is not limited in its ability to oscillate and thus in its amplitude and/or frequency by rigidity and/or strain. As a result, the oscillating system can be set specifically according to the needs of the user.

In addition, the elastic properties of the oscillating system are used and bring about a reduction in sound pressure (damping), while in the case of acoustic sound pressure waves with a small amplitude, the elastic system, in particular the spring element and the transducer carrier, is essentially acoustically transparent.

The following terms are explained:

In particular, a "sound transducer" is a device for transmitting and/or receiving underwater acoustic signals, such as is used when using active and passive sonars. The sound converter receives underwater sound signals and converts them into an electrical signal for further processing (receiver) and/or converts an electrical signal into an acoustic signal, with the latter being transmitted (transmitter). For example, hydrophones are used under water as sound transducers in order to record underwater sound noises there. A hydrophone converts the water noise into an electrical quantity corresponding to the sound pressure. When used under water, a frequency range between approximately 10 Hz and 1 MHz is used in particular.

An "acoustic converter element" is in particular a component of a sound converter or a hydrophone which converts acoustic signals as sound pressure changes into electrical voltage or, conversely, converts electrical voltage into acoustic signals. In particular in the ultrasonic range under water, piezoelectric transducers are nowadays used as the acoustic transducer element. In addition to piezoelectric ceramics, piezo elements are also made Known plastic, in particular polyvinylidene fluoride (PVDF) is used in hydrophones.

A "spring element" is in particular a component and/or a material which yields under load (tension or pressure) and returns to its original shape after the load is relieved, i.e., ideally, behaves in an elastically restoring manner. In particular, the spring element has high elasticity and low mass.

“Elastic” in this sense means in particular that the spring element or another elastic material deforms when pressure is applied, so that it assumes a different shape than before the pressure was applied. This deformation is essentially reversible and after the applied force/compression stress has ended, the spring element or the other material resumes its original shape. Consequently, a sound pressure is converted into a mechanical deformation.

A "filling compound" is understood to mean, in particular, a compound for filling the space between the acoustic transducer element and the transducer carrier and the other components of the sound transducer. This can be a plastic mass and/or cork and/or another filling material. In particular, soft polyurethane or polyoxymethylene can be used as the plastic. Material with a hardness of 40shore A to 60shore A and/or a modulus of elasticity between 5MPa and 250MPa is understood here as "soft". The hardness is according to the mass of the system and the to select the operating frequency range. In particular, the filling compound has the task of gluing the components of a sound transducer together and thereby ensuring stability. In addition, the filling compound can in particular also have an elastic and sound-damping effect. In addition, the filling compound prevents seawater from penetrating the transducer and causing corrosive damage in particular.

A "transducer support" is in communication with the acoustic transducer element and at least partially encloses the acoustic transducer element. The transducer carrier is arranged behind and next to the acoustic transducer element in the sound pressure direction. The transducer carrier is designed in particular to be elastic.

A "mass" is understood in particular as the mass of an oscillating system, which is rigid and free of elasticity. The mass is in particular excited by a sound field to oscillate and generates an electrical useful sound signal and/or, as a transmitter, a sound field output.

In the present case, “sound pressure direction” is understood to mean the direction from which the sound pressure with the highest intensity from a sound source impinges on the sound transducer. In the case of a receiver, the direction of sound pressure is in particular identical to the main direction of reception. In the case of a transmitter, the sound pressure direction is in particular opposite to the main transmission direction.

An "oscillating system" is in particular the arrangement of the acoustic transducer element and other components of the sound transducer for acoustic-mechanical and/or mechanical-acoustic conversion. In particular, the spring-mass principle is used in the oscillating system.

The "sensitivity" of a sound transducer is in particular a measure of the electrical voltage generated in relation to the sound pressure at a specific frequency in a sound receiver or a measure of the applied voltage in relation to the sound pressure generated at a specific frequency in a sound transmitter. In particular, the sensitivity can also be specified as a transfer factor, in which the output voltage (as open-circuit voltage) is specified in relation to the incident sound pressure for a receiver.

In a further embodiment of the sound transducer, a mechanically directly coupled impedance mass is arranged behind the acoustic transducer element in the sound pressure direction, with the first spring element and then the transducer carrier being arranged behind the impedance mass in the sound pressure direction.

Due to the direct mechanical coupling of an impedance mass to the acoustic transducer element, the oscillating system can be adjusted in a targeted manner.

In particular, an increase in sound pressure and thus amplification can be achieved through this direct mechanical coupling.

By introducing the impedance mass locally, the acoustic sensitivity of the acoustic transducer element (as receiver) and/or the radiated sound energy (as transmitter) can be increased by increasing the sound pressure.

Also, by arranging the first spring element and the subsequent transducer carrier behind the impedance mass, an impedance jump and thus soundproofing, in particular in front of the downstream acoustic absorber, can be achieved.

The acoustic effectiveness of the arrangement can thus be increased by additionally attaching an elastically mounted impedance mass. The effectiveness of the oscillating system can be optimized for the selected frequency range by selecting and arranging the impedance mass and/or the spring element and/or the spring stiffness.

An “impedance mass” is understood to mean, in particular, a mass made of a specifically heavy material compared to the surrounding material, in particular the surrounding acoustic transducer element, the filling compound and/or the spring element, as a result of which a jump in the acoustic impedance occurs. In particular, the impinging sound (pressure) is reflected and/or delayed by the impedance mass, so that an increase in sound pressure occurs on the side of the impinging sound (pressure).

On the other hand, due to the jump in impedance in particular, there is a transition to a specifically lighter material the impedance mass takes place a sound pressure damping. For example, brass with a density of approx. 8.41 g/cm ³ to 8.86 g/cm ³ can be used as an impedance mass for a greater increase in sound pressure, or aluminum with a density of approx. 2.7 g/cm ³ for a lower increase in sound pressure.

An impedance mass can be used in the sound pressure direction in front of and/or behind the acoustic transducer element.

In order to further adjust the oscillating system and to further improve the sound damping and the vibration-related decoupling, a second mass is arranged in front of and/or behind the acoustic transducer element in the sound pressure direction, with a second spring element being arranged between the second mass and the acoustic transducer element.

The acoustic effectiveness of the arrangement is further increased by the additional attachment of a second elastically mounted mass.

In addition, the effectiveness of the system for the selected frequency range can be further optimized by selecting and arranging the second mass for the acoustic transducer element as the first mass. The choice of the masses as well as the spring stiffness results from the desired frequency range.

The introduction of a second mass in front of the acoustic transducer element is particularly useful for compensating against high hydrostatic pressure and high sound pressure advantageous.

This arrangement is therefore advantageous in the case of a sonic shock pressure wave, since the sonic shock pressure wave first strikes the upstream second mass with high intensity. Shock absorption of the sound pressure occurs due to the elastically arranged second mass in front of it.

This arrangement has the advantage that two states of resonance (two-mass oscillator) of the acoustic transducer element can be used in order to increase the acoustic effectiveness on the one hand and at the same time to reduce direct shock pressure stress on the acoustic transducer element.

This "multi-mass oscillator" can be tailored to the respective application and the required frequency range by selecting material parameters such as mass (specific density, dimensions, acoustic impedance properties) and selecting the spring stiffness of the spring elements.

Both with upstream and downstream connection of a second mass, the elasticity of the overall system is increased by the introduction of a second spring element, so that the soundproofing and the vibration-related decoupling are improved.

The properties of the "second mass" largely correspond to those of the mass described above.

The "second spring element" corresponds in its structure and in its properties in particular to the first spring element described above.

In a further embodiment of the sound converter, the impedance mass and/or the second mass are greater than the first mass of the acoustic converter element.

As a result, on the one hand, there is a stronger jump in impedance between the acoustic transducer element and the impedance mass and also between the impedance mass and the spring element and between the second mass and the spring element.

Consequently, on the other hand, the incident sound pressure is increased by reflection and/or delay due to the greater mass.

The sound pressure can thus be increased on the front side by the larger mass, while sound pressure damping occurs behind the impedance mass and/or the second mass in the direction of sound pressure due to the jump in impedance.

In addition, this ensures that the larger amount of vibration energy is in the smaller mass of the acoustic transducer element, but at the same time an increase in sound pressure and/or sound damping is achieved by the impedance mass and/or the second mass.

In order to convert an acoustic signal into an electrical signal and/or to convert an electrical signal into an acoustic signal, the acoustic Transducer element on a piezo ceramic and / or a piezo composite ceramic.

A “piezo-ceramic” and/or a “piezo-composite ceramic” is understood to mean, in particular, a full ceramic or a composite material as the transducer element. While a piezoceramic is an all-ceramic, a piezocomposite ceramic consists of a composite material which has, in particular, piezoelectric, ceramic filaments and a filling compound.

Both ceramics act as piezo transducers and generate an electrical voltage when mechanical pressure is applied or perform a mechanical movement when electrical voltage is applied.

The ceramic filaments in the piezocomposite ceramic are in particular thin and/or thread-like structures. In particular, these can take the form of rods, cylinders, tubes and/or plates.

When impacting and/or imposing a sound pressure, the ceramic filaments are elastically deformed, with a change in the electrical polarization taking place and thus an electrical voltage being generated on the ceramic solid. Thus, the sound transducer is designed here as a sound receiver.

The piezoceramic and/or piezocomposite ceramic are usually designed with two conductive layers, through which a voltage is applied or discharged. The density of piezoceramics is around 7.7g/cm ³ , while the Density of piezo composite ceramic is lower and depends on the proportion of ceramic filaments and the filling compound.

In a further embodiment of the sound transducer, the first spring element and/or the second spring element has/have an elastomer and/or the transducer carrier has/have a fiber composite material.

This choice of material allows an elastic arrangement of the acoustic transducer element and/or the impedance mass and/or the second mass.

As a result, the oscillating system and the acoustic properties, in particular the sensitivity of the sound transducer, can be optimally adjusted for a specific frequency range.

This can also further improve the vibration properties of the system, the damping properties and the acoustic decoupling.

An "elastomer" is in particular a dimensionally stable but elastically deformable plastic. Elastomers can deform elastically under tensile and compressive loads, but then return to their original shape. In particular, rubber and/or polyurethane can be used as the elastomer. In addition to sound-damping properties, an elastomer can also have insulating properties.

A “fiber composite material” is in particular a multi-phase and/or mixed material usually consisting of two main components, one component being a matrix and the other being reinforcing fibers.

A "fiber" is in particular a structure that is thin and flexible in relation to its length and consists of a fibrous material. Here the ratio of length to diameter is at least 3:1 or preferably at least 10:1. In particular, fibers have a length to diameter ratio of 1000:1. Due to the length-diameter ratio, the fibers give the material the necessary reversible flexibility. In particular, glass fibers and/or carbon fibers can be used as fibers. As a plastic matrix thermosetting plastic such. As polyester resin and / or epoxy resin and / or thermoplastics such. B. polyamide used.

It is particularly advantageous that the required material properties and thus the elastic behavior of the transducer carrier can be adjusted by the choice and number of the fiber material as well as the matrix material.

In addition, the corrosion behavior of fiber-reinforced plastic in seawater is advantageous.

In a further aspect, the object is achieved by a converter device with a sound converter as described above.

As a result, several sound transducers can be arranged in parallel and/or in series and tuned to different frequency ranges. The converter device can thus be designed according to the needs of the user; in particular, the converter device can have different sound converters for transmitting and/or receiving.

In particular, several sound converters with different sensitivities and different frequency ranges can also transmit and/or receive in the converter device.

In a further aspect, the object is achieved by a sonar for transmitting and/or receiving acoustic underwater signals, the sonar having a sound converter or a plurality of sound converters as described above or a converter device or a plurality of converter devices as described above.

"Sonar" is a system for locating objects in space and under water by means of received sound pulses. This can be an active sonar, which itself emits a signal, or a passive sonar, which only receives emitted sound pulses. It can also be a bi- or multi-static sonar, which can transmit and receive on different platforms at the same time.

This transducer and / or transducer device are particularly advantageous for a sonar, since a location of unknown objects with high sensitivity and at different frequencies.

In addition, soundproofing is necessary, particularly in the case of sonic shock pressure waves, such as those that occur, for example, in the case of a nearby explosion. This ensures that the sonar's acoustic absorber remains intact.

In an additional aspect of the invention, the object is achieved by a watercraft, in particular a submarine, which has a sonar as described above.

For a submarine in particular, it is necessary for the sonar to be located, navigated and communicated with high sensitivities and different, wide frequency ranges. This is particularly advantageous since a submarine needs to detect and identify unknown sound sources underwater and identify potential hazards.

Furthermore, it is also advantageous here that the acoustic absorber of the sonar is not destroyed by a sound shock pressure wave, since otherwise the above-mentioned functions no longer exist and the submarine is endangered.

Figur 1

eine stark schematische Schnittdarstellung eines Schallsenders mit einer nachfolgenden Gummischicht und einem Wandlerträger sowie das zugehörige Masse-Feder-Schema,

Figur 2

eine stark schematische Schnittdarstellung eines Hydrophons mit einer piezoelektrischen Keramik, einem Messing-Block und einer Gummischicht sowie das zugehörige Masse-Feder-Schema,

Figur 3

einen schematischen, halbseitigen Schnitt durch ein aktives Bugsonar mit einer beispielhaft gezeigten Piezokomposit-Keramik, einem nachgeschalteten Messing-Block und zwei Gummischichten sowie das dazugehörige Masse-Feder-Schema und

Figur 4

ein schematischen, halbseitigen Schnitt durch ein aktives Bugsonar mit beispielhaft gezeigter Piezokomposit-Keramik mit einem vorgelagerten Messing-Block und zwei Gummischichten sowie das zugehörige Masse-Feder-Schema.

The invention is explained in more detail below using exemplary embodiments. Show it:

figure 1

a highly schematic sectional view of a sound transmitter with a following rubber layer and a converter carrier as well as the associated mass-spring scheme,

figure 2

a highly schematic sectional representation of a hydrophone with a piezoelectric ceramic, a brass block and a rubber layer as well as the associated mass-spring scheme,

figure 3

a schematic, half-page section through an active bow sonar with a piezo composite ceramic shown as an example, a downstream brass block and two rubber layers as well as the associated mass-spring scheme and

figure 4

a schematic, half-page section through an active bow sonar with piezocomposite ceramic shown as an example with a brass block in front and two rubber layers as well as the associated mass-spring scheme.

A sound transmitter 101 has a piezoelectric ceramic 105 which has a front copper layer 106 and a rear copper layer 107 . A rubber layer 108 follows behind the piezoelectric ceramic 105 in the sound pressure direction 102 and sits directly on a GRP carrier 103 . A PU mass 111 is arranged to the side of the piezoelectric ceramic 105 and the rubber layer 108 and connects the piezoelectric ceramic 105 and the rubber layer 108 to the GRP carrier 103 . In A PU high-frequency absorber 104 is arranged behind the GRP carrier 103 in the sound pressure direction 102 .

The piezoelectric ceramic 105 corresponds to a first mass 120. The first mass 120 is directly connected to the rubber layer 108, the rubber layer 108 corresponding to a spring 123. FIG. On the side facing away from the sound pressure direction 102, the spring 123 is connected to the GRP carrier 103 as an elastic mount 125. The thin front copper layer 106 and rear copper layer 107 are assigned to the first mass 120 in this case.

The sound transmitter 101 emits an acoustic signal counter to the sound pressure direction 102 . For this purpose, a voltage is applied between the front copper layer 106 and the rear copper layer 107, as a result of which the piezoelectric ceramic 105 expands and moves mechanically. The movement pressure is released into the surrounding water as sound pressure. Here, a frequency of 150kHz is used, which is broadcast with a high level of transmittance.

This is possible because the piezoelectric ceramic 105 is designed as a mass 120 and is arranged elastically by the rubber layer 108 following in the sound pressure direction 102 and the GRP carrier 103 . The sound transducer thus represents a simply elastically coupled system.

In an alternative exemplary embodiment, a hydrophone 201 has a piezoelectric ceramic 205 as a receiver, which initially has a front copper layer 206 and a rear copper layer in the sound pressure direction 202 207 has. Then follows in the sound pressure direction 202 a brass block 209 and a rubber layer 208, which sits directly on the GRP carrier 203. On the side, the piezoelectric ceramic 205, the brass block 209 and the rubber layer 208 are connected to the GRP carrier 203 via the PU mass 211. The PU high-frequency absorber 204 is arranged behind the GRP carrier 203 in the sound pressure direction 202 .

In this case, the piezoelectric ceramic 205 corresponds to the first mass 220 which is mechanically connected directly to an impedance mass 221 . The impedance ground 221 is carried out through the brass block 209. The rubber layer 208 corresponds to a spring 223 which connects the impedance mass 221 to an elastic mount 225, with the elastic mount 225 being designed as a GRP support 203.

Due to the mass ratios of the piezoelectric ceramic 205 and the GRP carrier 203, a brass block 209 is connected to the piezoelectric ceramic 205 as an additional and impedance mass and these are arranged elastically on the GRP carrier 203, which is also elastic.

The frequency range in particular is defined by the masses and the spring stiffness.

Since the brass block 209 has a higher specific mass than the piezoelectric ceramic 205, an acoustic impedance jump occurs. The brass block 209 reflects and delays the incident sound pressure, so that on the side of the incident sound pressure, a sound pressure increase occurs.

On the other hand, the impedance jump at the transition from the brass block 209 to the specifically lighter material of the rubber layer 208 results in sound pressure damping, so that the PU high-frequency absorber downstream of the GRP support 203 in the sound pressure direction 202 remains intact even when a sound shock pressure wave strikes.

In an alternative exemplary embodiment, an active bow sonar 301 has a multiplicity of piezocomposite ceramics 305, a sound transducer segment being described here by way of example.

In the sound pressure direction 302, there is first a copper grid 306 as a conductive layer, a piezo-composite ceramic 305, a rubber layer 308, a brass block 309 connected downstream and a rubber layer 310. A PU mass 311 is arranged on the side, which connects this sound transducer segment to the next, not segment shown, connects.

The rubber layer 310 connects this arrangement to the oscillating support 303, which is designed in the shape of a semicircle (only half of the semicircle is shown here) and can oscillate both in the sound pressure direction 302 and transversely to the sound pressure direction 302. The rubber layer 308 has both the task of damping and isolation, while the rubber layer 310 is used for damping and acoustic decoupling.

The piezo composite ceramic 305 corresponds to a first mass 320. The rubber layer 308 corresponds to a second spring 324 and the brass block 309 to a second mass 321. The first mass 320 is connected to the second mass 321 via the second spring 324. The second mass 321 is in turn connected to an elastic mount 325 via a first spring 323 , which is embodied through the rubber layer 310 , the latter being embodied by the oscillating support 303 .

In this alternative, the brass block 309 is arranged as an additional second mass 321 decoupled by the rubber layers 308 and the rubber layer 310 behind the piezoelectric ceramic 305 in the sound pressure direction 302 .

In this case, this system is again arranged in an elastically mounted manner on the oscillating support 303 . As a result, two states of resonance (two-mass oscillator) of the piezoelectric ceramic 305 are used in order, on the one hand, to increase the acoustic effectiveness and, at the same time, to reduce the sound shock wave stress.

In the sound pressure direction 302, a sound shock pressure wave occurs as a result of an explosion 50 m in front of the active bow sonar 301. Due to the double, elastic arrangement of the piezocomposite ceramic 305 via the rubber layers 308 and 310 and due to the impedance jump from the brass block 309 to the rubber layer 310, sound damping occurs. As a result, and due to the further elastic design of the vibrating beam 303, the Acoustic shock pressure stress is reduced and the pressure which is passed on by the vibrating beam 303 is reduced to the extent that a downstream acoustic absorber (not shown) remains intact.

In an alternative exemplary embodiment, an active bow sonar 401 has a plurality of piezocomposite ceramics, with only one piezocomposite ceramic 405 being considered as an example.

In the sound pressure direction 402, a sound pressure first hits a brass block 409, followed by a rubber layer 408, the piezo composite ceramic 405 and a subsequent rubber layer 410.

The rubber layer 410 connects this transducer arrangement to the oscillating support 403, which oscillates in the sound pressure direction 402 and transversely to the sound pressure direction when stressed.

The brass block 409 as the second mass 421 is connected to the piezocomposite ceramic 405 as the first mass 420 via the rubber layer 408 as the second spring 424 .

The piezocomposite ceramic 405 as the first mass 420 is in turn connected via the rubber layer 410 as the first spring 423 to the oscillating support 403 as the elastic mount 425 .

Due to the frequency range and the mass of the piezo composite ceramic 405 is in this Alternatively, the brass block 409 is elastically mounted as an additional mass in front of the piezo composite ceramic 405.

The piezocomposite ceramic 405 is in turn arranged elastically on the oscillating support 403 on the rear side. As a result, there is also a multi-mass oscillator in this alternative, which is matched to the application and the required frequency range by the selection of the material parameters of the first and second masses 420 and 421 and the spring stiffness of the rubber layers 408 and 410 .

The upstream connection of the second mass 421 is advantageous for the following application, in which an explosion occurs in the immediate vicinity of the active bow sonar 401 at a small distance of 20 m and a very strong sound shock pressure wave first hits the brass block 409 as the second mass 421. Due to the jump in impedance from the brass block 409 to the elastic rubber layer 408, sound pressure damping takes place before the sound pressure continues to impinge on the piezocomposite ceramic 405 following in the sound pressure direction 402. This avoids excessive stress on the piezocomposite ceramic 405 when the sound shock pressure wave hits the active bow sonar 401 .

The subsequent elastic arrangement of the piezocomposite ceramic 405 on the rear side via the rubber layer 410 and the elastic vibrating support 403 also prevents the downstream acoustic absorber (not shown) from being destroyed.

Reference List

101

sound transmitter

102

sound pressure direction

103

GRP carrier

104

PU high frequency absorber

105

Piezoelectric Ceramics

106

front copper layer

107

back copper layer

108

rubber layer

111

PU mass

120

mass 1

123

Feather

125

elastic mount

201

hydrophone (receiver)

202

sound pressure direction

203

GRP carrier

204

PU high frequency absorber

205

Piezoelectric Ceramics

206

front copper layer

207

back copper layer

208

rubber layer

209

brass block

211

PU mass

220

mass 1

221

impedance ground

223

Feather

225

elastic mount

301

active bow sonar

302

sound pressure direction

303

swing beam

305

Piezo composite ceramic

306

copper grid

308

rubber layer

309

brass block

310

rubber layer

311

PU mass

320

first mass

321

second mass

323

first spring

324

second spring

325

elastic mount

401

active bow sonar

402

sound pressure direction

403

swing beam

405

Piezo composite ceramic

408

rubber layer

409

brass block

410

rubber layer

411

PU mass

420

first mass

421

second mass

423

first spring

424

second spring

425

elastic mount

Claims (9)

1. Sound transducer (101, 201) for sending and/or receiving acoustic underwater signals, which comprises an acoustic transducer element (105, 205, 305, 405), at least one first spring element (123, 223, 323, 423), a filling compound (111, 211, 311, 411) and a transducer support (103, 203, 303, 403), the at least one first spring element being associated with the acoustic transducer element, wherein the acoustic transducer element is in the form of a first mass (120, 220, 320, 420) of an oscillating system, and in a sound pressure direction (102, 202, 302, 402) downstream of the acoustic transducer element the first spring element and then the transducer support are arranged , with the result that the oscillating system is set and therefore an acoustic sensitivity of the sound transducer is improved, characterized in that the transducer support at least partly surrounds the acoustic transducer element and wherein the transducer support is arranged downstream of and next to the acoustic transducer element in the sound pressure direction, and wherein a space between the acoustic transducer element and the transducer support and also further components of the sound transducer is filled by the filling compound.
2. Sound transducer according to Claim 1, characterized in that a mechanically directly coupled impedance mass (209, 221) is arranged downstream of the acoustic transducer element in the sound pressure direction, wherein the first spring element and then the transducer support are arranged downstream of the impedance mass in the sound pressure direction.
3. Sound transducer according to one of the preceding claims, characterized in that a second mass (309, 321, 409, 421) is arranged upstream and/or downstream of the acoustic transducer element in the sound pressure direction, wherein a second spring element (308, 324, 408, 424) is arranged between the second mass and the acoustic transducer element.
4. Sound transducer according to one of Claims 2 and 3, characterized in that the impedance mass and/or the second mass is larger than the first mass of the acoustic transducer element.
5. Sound transducer according to one of the preceding claims, characterized in that the acoustic transducer element comprises a piezo-ceramic (105, 205) and/or a piezo-composite ceramic (305, 405).
6. Sound transducer according to one of the preceding claims, characterized in that the first spring element and/or the second spring element comprises or comprise an elastomer and/or the transducer support comprises a fibre composite material.
7. Transducer apparatus having a sound transducer according to one of preceding Claims 1 to 6.
8. Sonar (301, 401) for sending and/or receiving acoustic underwater signals, characterized in that the sonar comprises a sound transducer or multiple sound transducers according to one of Claims 1 to 6 or a transducer apparatus or multiple transducer apparatuses according to Claim 7.
9. Watercraft, in particular a submarine, comprising a sonar according to Claim 8.

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