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
  • B06B1/0611—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 in a pile
  • B06B1/0618—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 in a pile of piezo- and non-piezoelectric elements, e.g. 'Tonpilz'
• • G—PHYSICS
  • G10—MUSICAL INSTRUMENTS; ACOUSTICS
  • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
  • G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
  • G10K11/004—Mounting transducers, e.g. provided with mechanical moving or orienting device

Definitions

• Ultrasonic transducers method for fixing ultrasonic trans ⁇ ducers and high output power ultrasonic transducers
• ultrasonics to solve various technical problems has very rapidly increased during the last decades.
• applications are e.g. technologies for space research, aviation, communication, marine applications, applications in the auto ⁇ motive and other industries, laboratory and medical applications, gas lighters, nebulizers and alarm systems.
• the electromechanical transducers most commonly used in said connections are using piezoelectrical materials, which convert mechanical energy into electrical energy or vice versa.
• the material can in addition be polarized to change dimension merely horizontally, vertically or radially depending upon which the desired effect is. Piezoelec ⁇ trical properties exist naturally in certain crystalline materials and can be made to exist in certain other polycristal- line materials.
• the ceramic elements can either be glued directly onto the structure one wishes to transmit the ultrasound to, or be used for the manufacture of ultrasonic transducers, which in turn are applied onto this structure.
• ultrasonic transducers For the transmission of high power ultrasonic transducers are used where the ceramic part has been precompressed by way of exposing it to a permanent compression caused by that two metal parts with the ceramic between them are compressed by means of one or several bolts which have been tightened using a torque so large that the desired pressure onto the ceramic part occurs.
• This design is generally referred to as a "sandwich transducer".
• Figs. 1 and 2 are examples of sandwich transducers
• Fig. 3 is an example of a mounting of two ultrasonic transducers
• Fig. 4 is a partially broken longitudinal section through an ultrasonic transducer also showing the mounting thereof to a structure
• Fig. 5 is a cross-section through an alternative embodiment of an ultrasonic transducer
• Fig. 6 is a longitudinal section through a further em ⁇ bodiment of an ultrasonic transducer.
• Figs. 1 and 2 show examples of sandwich transducers in different projections.
• the ceramic rings 3 are placed between the top metal part 1 and the bottom metal part 2, which have been tightened by means of the bolt 6, which in this case has been applied through a hole drilled through the bottom metal part and into a drilled and tapped hole in the top metal part whereafter it has been tightened by means of an applied torque which has been calculated so that the desired pressure is applied onto the ceramic rings.
• Between the rings is a contact shim with a solder tag 4 used for the connection to live and a corresponding shim with solder tag 5 between the ceramic ring and the metal part used for the connection to neutral .
• these are glued onto the wall or bottom of e.g.
• Fig. 3 shows a mounting of two ultrasonic transducers built up by that the bottom metal part 2 is an aluminium plate common to both transducers which in turn is then glued onto the bottom or walls of the tank as per above.
• the bolts used for applying pressure onto the ceramic rings are brought through two holes from the bottom side of the common bottom plate and through the ceramic rings into the drilled and tapped holes in the top metal part and tightened with a calculated torque to arrive at the desired pressure onto the ceramic rings.
• the transducers gets to be very complicated. In order to have the entire transducer to resonate at the desired frequency, one has to consider the influence of the lengths of the first metal section, the other metal section and the ceramic section as well as of speeds of sound, the cross section areas and the densities of these sections.
• the transmission of the ultrasonic wave and dissipation of heat from the first metal section to the other metal section and further on into the liquid is only done by means of the bolt which clamps the two sections together and then only by means of the pressure from the bolt head and the other metal section, which further reduces the efficiency and contributes to raise the transducer temperature.
• the transducer must be designed in such a way that it consists of only one single metal housing with encapsulated piezoelectrical elements so that one gets only one resonating unit and thus avoids the necessity to fit the dimensions of each single resonating element to be in common resonans with all the others at the same time and without any phase displacement of the frequency between the different elements.
• the efficiency for generating and transmitting of ultrasonic energy must be as high as possible and offer more ultrasonic transmission effect per contact surfae than does the present transducer technology.
• the method of mounting the transducer must be based upon direct metal to metal contact electrically as well as accous- tically and offer possibilities to a service based upon modular exchange of transducers.
• Transducers and method of mounting them must be adapted to one another in such a way that the distribution of ultrasonic energy into the liquid is as large as possible and so that no harmful concentrations of ultrasonic energy, so called “hot spots” will occur but that the ultrasonic energy will function in the same way and with the same concentration in the entire volume of the liquid.
• the transducer and the method of mounting the same must be individually designed in a way that they together function as one single unit in order to meet the above mentioned specifications.
• the transducer must have metal to metal contact between the different transducer elements and for external mounting they are fixed together with metal to metal contact into a fixing ring which in turn has been welded onto the surface which constitutes the base of the transducer installation.
• Fig. 4 shows an example of a cross section side-view of such a structure.
• the transducer consists of a core 1 located inside a bottom vessel 2 with two circular piezoelectric ceramic discs 3 with a contact shim with a solder tag 4 between them for cable connection to the generator live connector via the milled and drilled hole 5 through the core.
• the bottom vessel 2 is threaded in the bottom part in order to allow for screwing same into the threaded mounting ring 6 when fixing the transducer during the mounting.
• the bottom vessel 2 is also threaded at the top end to allow for screwing same into a threaded connector part 7 to allow for connecting several transducers together and for securing protected cable connections of the entire transducer assembly.
• a hole 5 has been drilled through the transducer core from the location of the solder tag of the contacts shim to the top center of the transducer core to allow for cable connection to the generator and thereafter one arranges total electrical insulation between the cable core and the transducer metal parts.
• the drilled hole is filled with epoxy or a similar type of sealing material in such a way that a complete sealing is achieved.
• the dimensions of the core 1 outside and the bottom vessel 2 inside diameters are selected such to each other that they can be regarded as one single metal part after one has been fixing them together by shrinking, welding or by another suitable fixing method.
• the cable is brought through the drilled hole 5 in the core 1 with insulated cable connection and cable, the core 1 is chilled by exposing it to e.g. liquid nitrogene.
• the core 1 is then positioned inside the bottom vessel 2 in a hydraulic press, where the two parts are pressed together with a pressure so high, that the desired precompression of the ceramic will occur. This can be controlled by means of a load cell mounted in the hydraulic press. As a safety precausion, the electrical voltage emitted by the piezoelectric ceramics 3 when exposed to a pressure is measured.
• the ceramic discs 3 do not meet specifications and the manufacture of this transducer is abandoned.
• the core 1 and the bottom vessel 2 have been shrunk together, they will be fixed together maintaining the same pressure by means of welding, pins, screws or the like, so that the desired pressure against the ceramic discs 3 will be maintained after that the transducer has been removed from the hydraulic press.
• the drilled hole 5 is filled from the bottom of the hole with a suitable sealing material e.g. epoxy. Since the transducer parts have been fixed together under a predetermined pressure, constant and repeatable transducer properties per tranducer type is secured.
• the mounting ring 6 When mounting the transducer, the mounting ring 6 is first welded onto the plate wall through which one desires to transmit the ultrasound into the liquid. Into the bottom of the cup formed that way, one applies an adhesive with a high content of a metal, e.g. colloidal silver. This is done to secure a very good metal to metal contact between the transducer and the plate despite the uneven surface of a product such as a welded stainless steel container. After that, the transducer is screwed into the mounting ring using a torque which secures that this contact is achieved and the connector part screwed onto the top part of the bottom vessel, the transducer cable will be connected to the high tension cable.
• a metal e.g. colloidal silver
• one has four transducer connections per connector pipe one can have a submersible unit which emits ultrasonic energy in all four directions, which can be a great advantage e.g. in an installation into a tank with large diameter and height.
• Submersible transducers will preferably be manufactured out of acid-proof materials, whereas transducers for external mounting generally will be manufactured out of dural, since this material transfers heat away from the transducer much better than does acid-proof materials.
• Transducers for external mounting in corrosive environment will of course also be manufactured out of acid-proof materials.
• Fig. 5 Another solution to the transducer design is shown in Fig. 5, where one as the piezoelectric element has used a piezoelectric ceramic pipe 1 coated in- and outside with silver. This pipe has been precompressed by positioning it between an inside pipe 2 and an outside pipe 3, where the diameters 4 and 5 have been dimensioned in such a way that one by cooling the inner pipe 3 and heating the outer pipe 2 arrives at a desired precompression onto the ceramic pipe 1, after that the temperatures of the elements have arrived at ambient or operation temperature. In such a way one can, by mounting several ceramic segments between long inner and outer pipes before the shrink compression is done, build together long transducer units where one can arrive at very high output power per transducer unit.
• Fig. 6 shows a length section of such a structure where a number of ceramic rings 1 with radial polarization have been positioned between an outer pipe 2 and an inner pipe 3.
• Each transducer end wall 4 which preferably is manufactured out of stainless steel, can be manufactured to make sure that the end connections are completely water and gas tight by means of welding, O-ring seals or the like. This manufacturing method thus allows for the manufacture of completely gas and water tight transducers very well suited as submersible ultrasonic units. Only two electrical connection points with connectors 6 and 7 are used on the inner pipe 3 and the outer pipe 2 and the emission will be radially outwards for submersible units. If the polarity is shifted, the ultrasonic power will be transmitted radially inwards to be used for e.g.
• the open area 8 inside the inner pipe will have to be used for the circulation of a cooling medium since the energy added to the inner pipe via the ceramic pipe will cause a temperature increase of pipe and ceramic and will have to be transferred away since it should otherwise increase the temperature of these parts to an unaccep ⁇ table level .
• the transducer unit Since the transducer unit is manufactured in the form of a cylindrical bar, the ultrasonic energy for submersible units will be emitted radially outwards, which means that the ultrasonic energy will be evenly distributed within the surrounding liquid. Point 6 of the transducer specification where this need has been identified has therefore been met in an ideal way. It offers possibilities to work with very high output power. If one uses ceramic rings with an outside diameter of 76 mm and with a wall thickness of 6,35 mm, a submersible unit could emit 10 kW and maybe up to 20 kW per meter transducer unit. For transducer units with transmission radially inwards, one reaches very high ultrasonic effect into the liquid pumped through the pipe even at very high rate of flow.
• transducer structure is not limited to com ⁇ pletely round profiles but can of course be used for all shapes of profiles, elliptical, quadrangular, hexagonal etc. where the ceramic part has a hole inside it so that by shrinking can achieve a precompression of the ceramic, so that it can be used for high power output installations.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Physics & Mathematics (AREA)
• Acoustics & Sound (AREA)
• Multimedia (AREA)
• Transducers For Ultrasonic Waves (AREA)

Applications Claiming Priority (5)

Publications (1)

Family

ID=26662340

Family Applications (1)

Country Status (6)

Cited By (1)

Families Citing this family (7)

Family Cites Families (10)

• 1996
  • 1996-07-05 JP JP9505077A patent/JPH11508750A/ja active Pending
  • 1996-07-05 WO PCT/SE1996/000888 patent/WO1997002720A1/en not_active Ceased
  • 1996-07-05 CA CA 2226276 patent/CA2226276A1/en not_active Abandoned
  • 1996-07-05 EP EP96923150A patent/EP0890292A1/de not_active Withdrawn
  • 1996-07-05 AU AU63741/96A patent/AU6374196A/en not_active Abandoned
  • 1996-07-05 CN CN 96196497 patent/CN1194087A/zh active Pending

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events