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
  • B06B3/00—Methods or apparatus specially adapted for transmitting mechanical vibrations of infrasonic, sonic, or ultrasonic frequency

Definitions

• the invention relates to a device for coupling ultrasound into a liquid or pasty medium and with the other generic features mentioned in the preamble of claim 1.
• a device for coupling ultrasound into a liquid or pasty medium and with the other generic features mentioned in the preamble of claim 1.
• Such a device is known from US Pat. No. 4,016,436.
• a waveguide is provided on one side of a tubular cavity resonator, which can be excited to resonant longitudinal vibrations by means of a piezoelectric transducer, which in turn converts electrical AC voltage output signals of an AC voltage generator into longitudinal mechanical vibrations.
• the cavity resonator is acoustically coupled to this transducer in a mechanically fixed manner in a flange-shaped area thereof.
• n denotes an integer
• c denotes the speed of sound in a steel-shaped resonator and for the mechanical resonance frequency of the waveguide acoustically coupled to the transducer and used to introduce ultrasound into the resonator.
• the speed of sound c is here by the relationship
• a cleaning device in which the material to be cleaned, e.g. a textile web that can be exposed to an ultrasound field is known to use a so-called broad horn for coupling ultrasound into a liquid bath through which the textile web is transported, which is used by means of an ultrasound transmitter both in the longitudinal direction - the excitation direction - and also in the transverse direction perpendicular thereto, in which the expansion of the width horn corresponds at least approximately to the width of the textile web to be cleaned, can be resonantly excited to vibrations.
• This broad horn is a flat rod-shaped, solid radiating body
• the cavity resonator is designed in such a way that the resonance condition is fulfilled for both longitudinal and transverse natural vibrations of its jacket.
• the vibration-active element is designed as a three-dimensional cavity resonator in which the propagation velocities vx and vr and thus also the wavelengths ⁇ x and ⁇ r of the vibrations, which are linked to deflections in the direction of the longitudinal axis (x-direction) and radially thereto are necessarily different.
• a "weak" coupling of the tubular cavity resonator and the waveguide is provided, weak coupling meaning that there is a significant phase shift between the resonant vibrations of the cavity resonator, on the one hand, and the resonant - longitudinal - vibrations of the waveguide .
• a weak coupling can be realized, for example, in that the waveguide is vibration-coupled to the cavity resonator with the cavity resonator via a resilient spring element, which can have the shape of a plate spring.
• the waveguide has a variety of longitudinal ones Must have carried out vibrations before the cavity resonator comes into resonance, that is to say vibrates at maximum amplitude, its length L_ is in accordance with the relationship
• FIG. 1 shows an embodiment of a device according to the invention for strong coupling between the cavity resonator and transducer, in a schematically simplified longitudinal sectional view
• FIG. 2 shows an embodiment of a device with a weak coupling between the cavity resonator and the transducer
• FIG. 4 shows an exemplary embodiment with excitation of the cavity resonator by means of two transducers excited in opposite phases.
• a device is denoted overall by 10, by means of its ultrasound into a fluid medium 11 which is thin or pasty or fluid-like, can be in powder form, for example.
• the device 10 comprises a transducer, designated overall by 20, which converts electrical energy offered in the form of an alternating voltage into (ultra) sound power and offers this sound power in the form of forced longitudinal vibrations of a cylindrical-block-shaped transducer block 21, a total of 24 referred to elongated cylindrical-tubular cavity resonator and a waveguide 23, which in turn is acoustically coupled to the transducer and is in the form of a circular cylindrical block, via which the longitudinal vibrations generated by the transducer in the jacket 36 of the cavity resonator 24 can be coupled.
• a transducer designated overall by 20
• the transducer 20, the waveguide 23 and the cavity resonator 24 are arranged in this order along a common central longitudinal axis 26 coaxially with respect to this and are mechanically fixed to one another.
• a central threaded bolt 22 is provided, which is in meshing engagement with threads 25 and 25 'of the waveguide 23 or the transducer block 21 arranged opposite one another, so that they rotate by mutual rotation the central longitudinal axis with their opposing ring end faces 17 and 18 can be pressed firmly against one another.
• the cavity resonator 24 can be firmly connected to the waveguide 23 by twisting about the central longitudinal axis 26 with respect to the latter, with the cavity resonator 24 also being connected an annular end face 29, which runs radially between the threaded jacket 32 and the inner lateral surface 41 of the resonator jacket 36, axially supports the end face 38 of the threaded section 28 of the waveguide 23 facing the cavity resonator 24.
• the radial width rb of the ring end face 29 of the cavity resonator jacket 36 also being included which is axially supported on the end face 38 of the waveguide 23 on the resonator side, at least and corresponds approximately to 0.7 times the value of the thickness 6 of the resonator jacket, which is determined by the relationship
• Cavity resonator 24 are designated.
• the diameter of the waveguide also has that of the outer diameter
• the transducer 20 comprises an electromechanical chip voltage / vibration transducer a piezoelectric column designated overall by 27, which can be excited by actuation with an alternating voltage to "thick" vibrations running in the direction of the central longitudinal axis 26, that is to say longitudinal changes in length, which is transmitted via the transducer block 21 and fixedly with it connected waveguides 23 can be transferred to the jacket 36 of the cavity resonator 24.
• the piezoelectric column 27 is realized by a plurality of piezoceramic ring washers 33, which are firmly clamped between a stable clamping ring 37 and the transducer block 21 by means of a central tensioning screw 34 and are synchronized in phase with the AC output voltage Ur of an AC voltage generator 35 in parallel Thickness vibrations can be excited.
• the AC output voltage of the AC voltage generator can be adjusted to the resonance frequency of the longitudinal natural vibrations of the waveguide 23, so that the latter can be excited to such vibrations in a resonant manner.
• the medium 11 to be subjected to the ultrasound treatment is received by a cylindrical-pot-shaped reactor vessel, designated overall by 12, which is closed on its underside by an annular disk-shaped base plate 13 which A central, circular opening 14 has on the outside edge area 14 ′, as shown in FIG. 1, lower edge area 14 'of which the device 10 can be fastened by means of a radial flange 30 of the waveguide 23, as schematically illustrated by screw-nut connections.
• light which are provided in an axially symmetrical grouping with respect to the central longitudinal axis 26 of the device 10.
• the radial flange 30 of the waveguide 23, viewed in the longitudinal direction thereof, is arranged in the middle between the end face 38 on the resonator side and the ring face 17 on the transducer side 17 of the waveguide 23, so that the central plane 40 of the flange running at right angles to the central longitudinal axis 26 of the device 10 30 in the case of resonant vibration excitation of the waveguide 23, a node plane of its longitudinal vibrations is presented again.
• the cavity resonator 24 is also excited to longitudinal vibrations, which are also accompanied by transverse vibrations, ie radially directed to the central longitudinal axis 26, due to the transverse contracton of the resonator jacket 36 associated therewith , by means of which ultrasound energy can be "radiated” via the outer and inner cylinder jacket surfaces 39 and 41 in the radial direction into the medium to be subjected to the ultrasound treatment.
• the propagation velocities vx and vr of the jacket vibrations in the longitudinal and transverse directions and thus also their wavelengths ⁇ x and ⁇ r differ in a characteristic manner, ie depending on the geometry of the resonator 24 and the type of resonator material.
• the waveguide 23 is operated in its mechanical resonance frequency fr, at which half the wavelength of the longitudinal vibrations that can be excited in the waveguide is equal to the mean one in axial direction Direction measured distance a of its end faces 17 and 38.
• the alternating voltage generator 35 can be tuned to such an extent that the resonant excitation of the waveguide 23 is ensured.
• the cavity resonator 24 is also tuned to the resonance frequency f of the waveguide 23 and is also designed in such a way that the resonance condition for both the longitudinal and the transverse Vibration modes of its jacket 36 is satisfied.
• the one from the coupling plane 42 in which the resonator-side end face 38 of the waveguide 23 is supported on the one annular end end face 29 of the cavity resonator 24, as shown in FIG. 1, and is firmly pressed against it, up to upper free end face 44 of the cavity resonator 24 measured length L of the same according to the relationship
• ⁇ V is selected.
• y Poisson's transverse contraction coefficient
• E denotes the elasticity coefficient (Young's modulus) of the material of the cavity resonator 24 and f the density thereof.
• the cavity resonator 24 is further designed such that, in addition to the relationship (2), the relationship also
• FIG. 3a in which the arrows 46 and radially directed outward Inward arrows 47 illustrate the deflections of the resonator jacket 36 with respect to its central longitudinal axis 26, which the resonator jacket 36 experiences - outside of a node plane - while maintaining its circular cross-section.
• the cavity resonator 24 can also be excited resonantly to natural vibrations of lower axial symmetry, for example to natural vibrations of its jacket 36, which have a 3-fold symmetry with respect to the central longitudinal axis 26 , in such a way that, viewed in the circumferential direction of the jacket 36, 60 'subregions 48, 49 and 51 of the resonator jacket 36 arranged equidistantly from one another experience outward deflections, while the complementary 60s arranged between two of these subareas Sub-areas 52, 53 and 54 of the resonator jacket 36 experience radially inward deflections, as illustrated by the corresponding directional arrows 56 and 57.
• FIG. 2 To explain a further exemplary embodiment of a device which can be used analogously to the device 10 according to FIG. 1 and is designated overall by 10 ', reference is now made to FIG. 2, in which, for the sake of simplicity, the device 10' only by its transducer 20, the waveguide 23 'and the cavity resonator 24' acoustically coupled therewith and the assembly and coupling elements provided for their acoustic coupling are shown.
• the device 10 'according to FIG. 2 differs from the device 10 according to FIG.
• the cavity resonator 24' is connected to the waveguide 23 'in the sense of a "weak" acoustic coupling which causes that the cavity resonator 24 'and the cylindrical-rod-shaped block 58 of the waveguide 23' can perform longitudinal relative movements with respect to one another, this weak coupling resulting in the result that, in the case of resonance, the longitudinal movements of the cavity resonator 24 'with respect to the longi Ududinal vibrations of the waveguide 23 'have a significant phase shift.
• the - acoustic weak coupling of the tubular cavity resonator 24 'and the rod-shaped block 58 of the waveguide 23' is achieved by supporting a radially tapering support flange 60 on an inner support surface 59 of the cavity resonator 24 'which is conically complementary in an outer radial area, which mediated between jacket sections 36 'and 36''of different thicknesses 0 and 0 1, the outer diameter Do of both sections 36' and 36 '' being the same.
• the section 36 ′′ of the smaller thickness o viewed in the direction of the central longitudinal axis 26 of the device 10 ′, has an axial extent that corresponds to 1/8 of the wavelength * ⁇ , which in the case of resonant vibration excitation of the cavity resonator 24 ′ corresponds to the wavelength ⁇ of the longitudinal vibration excitation in the cavity 24 '.
• the radial outer edge 60 'of the support flange 60 which is designed in the form of a wedge or a wedge, as shown in the longitudinal section in FIG.
• a tubular spacer 61 which is enclosed by the thin-walled section 36 ′′ of the cavity resonator jacket 36 ′ and coaxially and at a slight radial distance from it, engages by means of a union nut 62 which is connected to an external thread 63 of the thin-walled section 36 '' of the thickness o 1 of the resonator jacket 36 'is in meshing engagement and to a predetermined The value of the axial force with which the waveguide 23 'is axially supported via its support flange 60 on the conical support surface 59 of the cavity resonator 24' is pressed against the annular disk-shaped flange region 60 ''.
• the latter acquires the property of a spring, similar to that of a plate spring, which provides the axially flexible connection - coupling - of the cavity resonator 24 'with the tab-shaped block 58 of the waveguide 23' ⁇ telt.
• a higher Q factor which is generally defined by the ratio of the emitted acoustic power to the electrical excitation power required for this.
• the cavity resonator 24 'of the device 10' is to oscillate in the axially fully symmetrical waveform (FIG. 3a) in the case of resonance, it is designed such that its length Lw in addition to the condition (3) also the condition
• the device 10 ′′ shown as a further exemplary embodiment in FIG. 4, to which reference is now made, in a highly simplified, schematic form, is the device 10 ′ according to FIG. 2, both in a constructive manner and also in FIG From a functional point of view, it is largely analogous and differs from this only in that an acoustically weak transducer and waveguide 23 'of the type described with reference to FIG. 2 are provided at each end of its tubular cavity resonator 24'' is to achieve higher amplitudes of the transverse vibrations of the cavity resonator 24 ′′.
• the piezoceramic columns or magnetostrictive transducers of these transducers 20 'and waveguides 23' - not specifically shown - are controlled by means of the alternating voltage generator 35 'in such a way that they are excited to oscillations in opposite phases.
• the condition that the cavity resonator 24 'fulfills both the resonance condition for longitudinal resonant vibrations and for transverse resonant vibrations can be achieved in the device 10' 'according to FIG. 4 in that the length Lw' of the cavity resonator
• n is an integer> _ 2.
• the cavity resonator 24 ′′ of the device 10 ′′ according to FIG. 4 is to be operated with the fully symmetrical radiation characteristic according to FIG. 3a, the cavity resonator sonator 24 '' designed such that in addition to the relation (4) also the relation
• the cavity resonator 24 ′′ is designed such that its length Lw ′ in addition to the condition (4) also the condition
• the devices 10, 10 'and 10' 'explained with reference to FIGS. 1, 2' and 4 '' can be used for cleaning workpieces, for stimulating chemical reactions, for mixing several liquid or pasty components of foods, for emulsification. and the like are used.
• a modification (not shown) of the exemplary embodiments according to FIGS. 1 and 2 can also consist in that the resonator 24 or the resonator 24 'is terminated at its end, e.g. through a plate that is firmly attached to the resonator tube.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Apparatuses For Generation Of Mechanical Vibrations (AREA)
• Surgical Instruments (AREA)
• Inks, Pencil-Leads, Or Crayons (AREA)

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• 1995
  • 1995-10-20 DE DE19539195A patent/DE19539195A1/de not_active Withdrawn
• 1996
  • 1996-10-17 DE DE59602406T patent/DE59602406D1/de not_active Expired - Fee Related
  • 1996-10-17 AT AT96934714T patent/ATE181857T1/de not_active IP Right Cessation
  • 1996-10-17 EP EP96934714A patent/EP0857088B1/fr not_active Expired - Lifetime
  • 1996-10-17 US US09/051,876 patent/US5994818A/en not_active Expired - Fee Related
  • 1996-10-17 WO PCT/EP1996/004502 patent/WO1997015404A1/fr active IP Right Grant

Non-Patent Citations (1)

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