Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B06—GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS IN GENERAL
  • B06B—METHODS OR APPARATUS FOR GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS OF INFRASONIC, SONIC, OR ULTRASONIC FREQUENCY, e.g. FOR PERFORMING MECHANICAL WORK IN GENERAL
  • B06B1/00—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency
  • B06B1/02—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy
  • B06B1/06—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with piezoelectric effect or with electrostriction
  • B06B1/0607—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with piezoelectric effect or with electrostriction using multiple elements
  • B06B1/0622—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with piezoelectric effect or with electrostriction using multiple elements on one surface
  • B06B1/0633—Cylindrical array

Definitions

• the present invention relates to acoustic transmission antennas which have the shape of a ring and which are removable. Such antennas are particularly useful for low frequency long range sonars.
• a screw-based device allows the corners to move towards the center of the ring, which tends to separate the segments from each other. The segments are thus pressed against the hoop ring and a preload of all the segments is obtained.
• a major advantage of this construction is to make the device entirely removable very easily, in order to be able, for example, to replace a defective part.
• the preload can be very easily adjusted by adjusting the screws until the desired characteristics, which are then continuously measured during this action, are obtained.
• Such an emission transducer can easily be produced with a diameter situated in a relatively large range of dimensions. It is however more difficult, for both mechanical and acoustic reasons, to manufacture a transducer of this type with a relatively large height.
• the invention provides a removable annular acoustic emission antenna, of the type comprising at least one prestressed ring formed by a set of piezoelectric segment grouped to form substantially identical sectors, with fixed end pieces.
• a shaping hoop making it possible to maintain all of the sectors, and means of allowing the clamping shims to slide towards the inside of the ring to pre-stress the segments on the hoop, characterized in that it comprises a set of substantially identical rings superimposed one above the other so that the shims is facing each other, two profiled rings of the same diameter as the prestressed rings and placed r respectively at the two ends of the stack, and a set of tie rods passing respectively through the groups of superimposed shims by means of longitudinal holes drilled in these shims to be fixed to the profiled crowns in order to press the rings against each other .
• it comprises two envelopes of elastic material covering respectively the external and internal faces of the cylinder formed by the stack of rings, and each comprising flanges anchoring in peripheral grooves formed in the faces of the crowns profiles located from the other side of the faces of these crowns coming to bear on the rings.
• it further comprises two flanges in the form of crowns fixed respectively on said surfaces of profiled crowns to hold said flanges in said peripheral grooves.
• it comprises insulating rings inserted between the superimposed rings.
• it further comprises rings of elastic material interposed between the profiled rings and the insulating rings located under these rings to acoustically decouple the rings from the holding structure thereof.
• the tie rods form screws, the heads of which come to bear on the external face of one of the profiled rings and the other ends of which are threaded and which are screwed into tapped blind holes, drilled on the inner face of the other profiled crown.
• the antenna power connector and the inflation tip of the latter are fixed on elastic supports which are themselves fixed on the external wall of the internal protective envelope of the antenna.
• the active elements of this ring are formed by a set of trapezoidal segments 1 01 of piezoelectric ceramic arranged against each other with alternating polarizations to constitute the sectors 1 02 of a circular ring.
• These sectors are assembled inside a hoop 108 which makes it possible to maintain them to obtain the shape of the circular ring intended to emit acoustic waves in radial symmetry.
• the corners 1 06 have their large base inside the ring and their small base on the side of the hoop.
• the shims 109 have their small base directed towards the inside of the ring and their large base towards the hoop.
• These shims 1 09 have on their small base tapped holes 1 1 0 into which are screwed screws 1 1 1 provided with washers 1 1 2.
• a number of rings such as that described above are placed one above the other to obtain a master cylinder whose emission characteristics, the power available without deterioration in particular, are those desired.
• three rings 201 to 203 were used.
• insulating layers 204 manufactured with a material having the necessary characteristics, for example a plastic material known under the registered trademark " DELRIN ".
• a thickness of approximately 1 mm of such a material makes it possible to obtain the desired characteristics.
• the rings are placed on top of each other in such a way that the active segments 1 02 are superimposed in continuity with one another, which means that the corners 1 06 and the shims 1 09 are themselves superimposed with respect to the other.
• longitudinal holes 205 were made in the shims 109, one per shim, which connect the upper face and the lower face of these shims, as shown in FIG. 3.
• the tapped holes 1 1 0 are d 'A depth shallow enough not to lead into hole 205, so as not to risk disturbing the assembly described below.
• each of the superimposed shims are then in the extension of one another, which makes it possible to pass through tie rods 206 which make it possible to secure the rings with each other.
• two rings 207 and 208 are used, the faces of which are in contact with the emitter rings 201 to 203 are planar and the faces situated on the other side are machined in the form of a profile with grooves whose function will be described later.
• the lower profile 208 is pierced with holes which are opposite the holes 205 of the ring 203, in order to allow the tie rods to pass therein.
• tie rods 206 are threaded and are screwed into tapped blind holes 209 drilled in the profile 207 directly above the rods 206.
• This construction method is the simplest, but other variants could be used such as for example a hole opening on the upper face of the section 207 and a nut which is screwed onto the screw 206, or threaded rods at both ends passing through the two sections 207 and 208 and each provided with their ends with nuts intended for secure the assembly.
• the sections 207 and 208 therefore have a flat lower face allowing to rest on the rubber crowns and an upper face having external peripheral grooves 21 3 and internal 21 4.
• the external and internal faces of this assembly are covered with two layers of rubber respectively 21 5 and 21 6 which form envelopes intended to ensure the tightness of the stack with respect to external agents, in particular sea water in which the device must be immersed.
• These envelopes have at their ends rims 21 7 and 21 8, obtained for example by machining or by molding, which come to be embedded respectively in the grooves 21 3 and 214.
• profiles with several successive grooves could be used adapted to an adequate molding of the edges of the envelopes, so as to increase the length of the joint between these edges and these grooves to obtain a better seal.
• Sealing is itself obtained by pressing the flanges in the grooves using two upper and lower fixing flanges 21 9 and 220 in the form of crowns which are assembled on the profiles by screws 221.
• these flanges have a median shoulder 222 which comes to rest against a mediating circular projection 223 formed on the top of the profiles and concentric with the groove 21 3, so as to be able to center each flange on the profile without difficulty. corresponding, by fitting it like a cover.
• the crowns can be machined to eliminate the internal excess thickness 230, corresponding to the offset in height of the groove 314 relative to the groove 21 5, in order to minimize the inactive weight of the assembly as much as possible.
• a multi-wire connector 224 is used, which is placed in a connector 225 produced in the same material, for example rubber, that the inner casing 21 6.
• This nozzle is fixed to the outer face of this inner casing so as to protrude into the interior space of the transducer.
• the fixing is effected by any known means for connecting pieces of material of this nature, for example by vulcanization.
• a valve 226, allowing the filling of the interior space of the transducer with an appropriate fluid, oil for example, is fixed by means of a nozzle 227 on the interior envelope 21 6.
• three rings have been assembled, each comprising 1 4 segments and whose internal and external diameters are substantially 450 and 600 mm.
• the active mass / total mass ratio of this device is greater than 75%, which is a particularly remarkable value.
• the antenna thus obtained is, as can be seen, entirely removable and reassemblable, which makes it possible to easily and quickly replace a segment which would prove to be defective.
• the holding structure of a towed fish for example, one or the other is used, or the two flanges 21 9 and 220.
• the layers of rubber 21 1 then make it possible to decouple acoustically the antenna of this structure.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Transducers For Ultrasonic Waves (AREA)
• Measurement Of Velocity Or Position Using Acoustic Or Ultrasonic Waves (AREA)
• Apparatuses For Generation Of Mechanical Vibrations (AREA)

Applications Claiming Priority (3)

Publications (2)

Family

ID=9523862

Family Applications (1)

Country Status (7)

Families Citing this family (5)

Family Cites Families (17)

• 1998
  • 1998-03-10 FR FR9802912A patent/FR2776161B1/fr not_active Expired - Lifetime
• 1999
  • 1999-03-09 DE DE69917235T patent/DE69917235T2/de not_active Expired - Lifetime
  • 1999-03-09 EP EP99907670A patent/EP1062055B1/de not_active Expired - Lifetime
  • 1999-03-09 US US09/623,851 patent/US6345014B1/en not_active Expired - Lifetime
  • 1999-03-09 AU AU27323/99A patent/AU747667B2/en not_active Expired
  • 1999-03-09 JP JP2000535464A patent/JP4031198B2/ja not_active Expired - Fee Related
  • 1999-03-09 WO PCT/FR1999/000523 patent/WO1999046059A1/fr not_active Ceased

Non-Patent Citations (1)

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