CA1307555C - Piezoelectrically excitable resonance system - Google Patents
Piezoelectrically excitable resonance systemInfo
- Publication number
- CA1307555C CA1307555C CA000572482A CA572482A CA1307555C CA 1307555 C CA1307555 C CA 1307555C CA 000572482 A CA000572482 A CA 000572482A CA 572482 A CA572482 A CA 572482A CA 1307555 C CA1307555 C CA 1307555C
- Authority
- CA
- Canada
- Prior art keywords
- disc
- resonance system
- working plate
- shaped
- base plate
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
- 239000007788 liquid Substances 0.000 claims abstract description 27
- 238000002604 ultrasonography Methods 0.000 claims abstract description 21
- 239000002184 metal Substances 0.000 claims abstract description 18
- 229910052751 metal Inorganic materials 0.000 claims abstract description 18
- 230000007704 transition Effects 0.000 claims description 6
- 230000001154 acute effect Effects 0.000 claims 1
- 210000004072 lung Anatomy 0.000 abstract description 4
- 230000005284 excitation Effects 0.000 description 9
- 229910000831 Steel Inorganic materials 0.000 description 3
- 238000000889 atomisation Methods 0.000 description 3
- 229910052759 nickel Inorganic materials 0.000 description 3
- PXHVJJICTQNCMI-UHFFFAOYSA-N nickel Substances [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 3
- 239000010959 steel Substances 0.000 description 3
- 230000001914 calming effect Effects 0.000 description 2
- 230000008878 coupling Effects 0.000 description 2
- 238000010168 coupling process Methods 0.000 description 2
- 238000005859 coupling reaction Methods 0.000 description 2
- 239000000443 aerosol Substances 0.000 description 1
- 238000005452 bending Methods 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 230000000644 propagated effect Effects 0.000 description 1
- 239000007921 spray Substances 0.000 description 1
- 238000009827 uniform distribution Methods 0.000 description 1
- SYOKIDBDQMKNDQ-XWTIBIIYSA-N vildagliptin Chemical compound C1C(O)(C2)CC(C3)CC1CC32NCC(=O)N1CCC[C@H]1C#N SYOKIDBDQMKNDQ-XWTIBIIYSA-N 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
- B05B17/00—Apparatus for spraying or atomising liquids or other fluent materials, not covered by the preceding groups
- B05B17/04—Apparatus for spraying or atomising liquids or other fluent materials, not covered by the preceding groups operating with special methods
- B05B17/06—Apparatus for spraying or atomising liquids or other fluent materials, not covered by the preceding groups operating with special methods using ultrasonic or other kinds of vibrations
- B05B17/0607—Apparatus for spraying or atomising liquids or other fluent materials, not covered by the preceding groups operating with special methods using ultrasonic or other kinds of vibrations generated by electrical means, e.g. piezoelectric transducers
- B05B17/0623—Apparatus for spraying or atomising liquids or other fluent materials, not covered by the preceding groups operating with special methods using ultrasonic or other kinds of vibrations generated by electrical means, e.g. piezoelectric transducers coupled with a vibrating horn
-
- 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
- B06B3/04—Methods or apparatus specially adapted for transmitting mechanical vibrations of infrasonic, sonic, or ultrasonic frequency involving focusing or reflecting
Abstract
ABSTRACT OF THE DISCLOSURE
For generating liquid droplets which may pass into the lungs of a person, a resonance system is used which contains a rotation-symmetrical metal body with a disc-shaped base plate, a working plate, a neck connecting the working plate to the base plate as well as a piezoceramic vibrator. The vibrator is coupled to the plane base surface which extends perpendicularly to the symmetry axis of the metal body. The base plate is also provided with a parabolic reflector surface. The center of the working plate is in the vicinity of the reflector focal point, optionally mirrored with respect to the base area of the base plate, of the parabolic reflector surface. In this design, ultrasound waves excited by the vibrator are focused into the region of the working plate, thereby atomizing a liquid which is held by the working plate.
For generating liquid droplets which may pass into the lungs of a person, a resonance system is used which contains a rotation-symmetrical metal body with a disc-shaped base plate, a working plate, a neck connecting the working plate to the base plate as well as a piezoceramic vibrator. The vibrator is coupled to the plane base surface which extends perpendicularly to the symmetry axis of the metal body. The base plate is also provided with a parabolic reflector surface. The center of the working plate is in the vicinity of the reflector focal point, optionally mirrored with respect to the base area of the base plate, of the parabolic reflector surface. In this design, ultrasound waves excited by the vibrator are focused into the region of the working plate, thereby atomizing a liquid which is held by the working plate.
Description
~3~555 BACKGROUND OF THE INVENTION
a. Field of Invention This invention pertains to devices for generating resonance vibrations in the ultrasonic-frequency range, and more particularly to a piezoelectrically excitable resonance system, which can be used to diffuse, spray or atomize liquids.
b. Description of the Prior Art One device for atomizing liquid described in United States Patent No. 3,9~4,896 (DE-A1 2,032,433) consists of a metal body having rotational symmetry, and a piezoceramic vibrator coupled to a base area of the metal body. The metal body o~ this resonance system designed for bending excitation has three regions, namely, a disc shaped base plate, a vibrating plate designating the working plate, and a stem which connects the base plate and the working plate and which coincides ~ith the axis o~ symmetry of the metal body. The working plate sexves, ~or instance, for containing a liquid. Liquids atomized with such a resonance system have droplet diameters which, generally, are not small enough to penetrate all the way into the lungs o~ a person. Such a resonance system is there~ore not very suitable ~or atomizing liquids used for inhalation purposes.
For improving the above-mentioned liquid atomizer/ it has been proposed to design the working plate as a concave mirror while the base plate is cone~shaped, and to connect it to the conical base plate via a neck having a special shape. Thereby, very small volumes of liquid (15 microliters or less~ can be . , . . ~ il ~
~75i~5 atomized by using thickness resonance excitation, without a mechanical droplet filter, with a small electric excitation power and without coupling through a liquid medium, - la -to ~orm droplets with a dlameter smaller than or equa:L to 40 micrometers. The vibration frequency o~ this resonance system is in the megahertz range. ~ 3 ~ 7 OBJECTIVES AND SUMMARY OF THE INVENTION
It is an object of the invention tn provide an improved resonance system which requires a small electric excitation power, and in which droplets can be generated which have diameters smaller than 15 micro~eters. Droplets of this size penetrate into lungs easier than droplets of larger diameters.
According to the invent;on a piezoceramic resonance system comprises a resonance vibrator attached to a base plate having a parabolic cover or re~lector surface opposite a base area, and a working plate which is disc or shell-shaped. The center of the working plate is located at the focal point or in the vicinity of the focal point of the parabolic cover or reflector surface. PARABOLIC REFLE~TOR SURFACE is understood to mean within the scope of the invention, a surface which reflects incident ultrasonic waves toward a focal point. Such a surface may be approximated by a spherical surface or a surface generated by a paraboloid of ring-shaped subsurfaces (i~e., a plurality of truncated cone surfaces with different cone aperkure angles).
Reflection toward the ~ocal polnt may be direct or via the base plate, as will become more obvious later.
In a resonance system designed in this manner, the ultrasonic waves generated by the plezoceramic vibrator in a direction transversal to a major axis of the vibrator are in- 1 jected into the metal body. They are reflected at the parabolic reflector surface o~ the base p~ate and are ~ocused through the neck into the region of the worklng plate. Since the ultrasonic waves strike the working plate at an angle of inclination7 part of these sound waves is reflected in the direction of the rim ~L3~7~S~ i of the working plate or proceeds as a surface wave in the direc-tion of the rim. Thereby, a uniform distribution of the liquid to be atomized on the working plate and a uniform atomization over the entire atomizing time are obtained. In addltion, the liquid surface is located in the vicinity of the optimum atomizing point during the entire atomizing operation. Consequently, devices can be produced with an excitation power smaller than or equal to 20 W, in which more than 50% of the atomized liquid comprises droplets of 15 micrometers or less. Typically, the most frequent droplets may have a diameter smaller than or equal to 5 micrometers which is excellent for inhalation purposes. Furthermore, a given reso-nance frequency may be obtained since manufacturing tolerances of the resonance system may easily be controlled.
In a further embodiment of the invention, the metal body of the resonance system can be designed so that the base surface of the base plate is a circular ring and the base plate includes a transition into a conical neck which passes through the opening of the circular ring and extends above the base plate. Thereby, a relatively compact design is obtained for the resonance system. In this latter case, the piezoceramic thlckness vibrator has likewise the form of a circular ring.
In this embodiment, the workin0 plate may be integrated directly in the neck, the neck being designed as a truncated cone with a dise or shell-shaped depression or cavity at the tapered end. In this embodiment, the focal point of the ultrasonic waves can be placed in the cavity of the cone apex and thereby directly in the liquid to be atomized.
The resonator may also be designed so that the conical neck is provided at the tapered end with an enlargement to form the disc-shaped working plate. This makes it possible to atomize a larger quantity of liquid.
A particularly advantageous embodiment of the metal Ii ;~
~3~555 body comprises a base plate which changes into the neck supportiny the disc-shaped working plate on the side of the parabolic cover surface in the vicinlty of the axis of symmetryq In this embodi-ment, the ultrasonic waves are reflected twice before they strike the working plate. Interference effects, beam offsets (see German !
periodical "Materialprufung", 1965, pages 281 et al.) and re-entrance of the ultrasonic waves into the piezoceramic vibrator associated with this double reflection lead to parallel beam displacements9 whereby the feeding or coupling of the ultrasound into the liquid to be atomized is improved. This can be further improved by a special design of the working plate. This design consists in that the side portion of the disc-shaped working plate forms a conical surface. The transition zone between the neck and the disc-shaped working plate and the inclination of the side part relative to the middle part of the disc-shaped working plate are chosen so that sound waves reflected at the disc-shaped working plate are directed into the side part and then back to the liquid-plate interface. These multiple re~lections improve the efficiency of the resonance system.
The dimensions of the resonance system depend on the velocity of sound in the metal body, which preFerab~y consists of chrome-nickel steel, and on the desired ~requency which should be in the most advantageous transmission range o~ thé piezoceramic thickness vibrator. Since the continuous atomiza'cion of a liquid is preferably accomplished with standing ultrasonic waves, the ultrasound travel distance in the metal body should be a multiple of half a wavelength. For example, the ultasound travel distance may be 6 to 28 times its hal~ wavelength.
In view o~ the design with double reflec'cion o~ the ultrasonic waves, the thickness o~ the base plate should be about twice the ultrasound wavelength 9 and the diameter o~ the disc-shaped working plate should be about three times this wavelength.
1 ~
~30~5S~ 20365-2832 The diameter of the base area of the disc-shaped base plate should be approximately ten -times the wavelenyth. The height of the neck, i.e. the distance between the apex of the parabolic cover surface and the center of the disc-shaped working plate, should advantageously correspond to one wavelength.
According to a broad aspect of the invention there is provided a piezoelectrically excitable resonance system or atomizing a liquid, comprising: a metal body with rotational symmetry and capable of vibrating, said body including a disc-shaped base plate having a reflector surface with a focal point, a working plate disposed at least in the vicinity of said focal point for holding said liquid, and a neck connecting the working plate to the base plate; and a piezoceramic vibrator which is coupled to a plane base surface of the base plate perpendicular to the axis of symmetry, said piezoceramic vibrator operating as a thickness resonance vibrator.
BRIEF DESCRIPTIOW OF THE FIGURES
Figure 1 shows a resonance system according to theinvention wi-th a si.ngle reflection, and with a working plate being integral with the neck;
Figure 2 shows a resonance system according to the invention with a single reflection, and with a working plate being formed at the neck as a disc-like member; and Figure 3 shows an embodiment according to the inven-tion in which the ultrasound waves are reflected twice before they strike a disc-shaped working plate adjacent -to -the neck~
".
~., jl ~3~ 0365 2832 DETAILED DESCR TION OF TH:E DRAWING
Figure 1 shows a vibrating or resonance system wh.ich consists of a metal body 1 with rota-tional symmetry, preferably made out of chrome-nickel steel, and a piezoceramic vibrator 7.
The axis of symmetry is designated 10~ The vibrator 7 generates ultrasonic waves in a direction transversal to its major axis, upon excitation in response to an AC signal (-thickness excitation).
Geometrically, the one-piece metal body 1 may be considered as an annular member which is penetrated by a cone with a paraboloidal bottom surface, the annular par-t and the cone having the same axis 10 of symmetry and the same outside diameter~ Thus, this metal body 1 has a disc-shaped base plate 2 with a planar base surface 3 extending perpendicularly to the axis 10 of rotation and a parabolic reflector surface 4 opposite thereto~ The body 1 further includes a conically tapered neck 5 which pene-- 5a -,,, ,~. .
trates the annular base sur Face ~ and reaches beyond lts plarle.
The neck 5 is designed at the acutely tapered end with a dlsc or shell-shaped depression 6. The depression 6 forms the working ' plate o~ the resDnance system and is designed ~or receivlng a li-i quid to be atomized. The center of the depression 6 is located at the focal point Fl of surface 4 or in the proximity the~eof. The piezoceramic ultrasownd transducer or vibrator 7 of annular confi-guration is attached or coupled to the planar base surface 3 which is arranged vertically with respect to the symmetry axis 10. The transducer 7 is positioned symmetrically with respect to axis 10.
During operation it works in the so-called thickness resonance excitation mode, as is conventional in ultrasound techniques.
An ultrasound wave US generated by the piezoceramic vlbrator 7 upon electrical excitation is propagated into body 2, is reflected at the parabolic re~lector surface 4 and is thereby focused in the direction toward the shell-shaped depression 6. In the focal point Fl, i.e. basically in the entire region of depression 6, wave US leads to an atomization o~ the liquid, thereby generating a multiplicity o~ droplets having a very small diameter, such as 15 or 5 micrometers or even less.
In the embodiment o~ Fig 2, the resonance system is similar to the embodiment of Fig. 1, i.e. it comprLses a one-piece metal bocly 11 of rotakional symmetry ~ith respect to an axis 2û. The body 11 consists of a disc-shaped base plate 12 with a planar annular base surface 13, a parabolic reflector sur~ace 14 at the opposite side thereof, and a conically tapered neck 15.
Again the neck 15 extends beyond the surface 13. The working plate is provided here by a disc-shaped enlargement or member 16 which is ~ormed at the acutely tapered end of the neck 15, as shown, at or near the focal point F2 of surface 14 The disc-shaped part 16 has a planar middle portion I6' and a conical side portion or side wall 16~'.
I .",. ,~
1 3 075 S ~ !
The ~esonance system is exclted by eneryizing a pie~oceram:Lc rirly body 17 which is coupled or cemented to the body 11 (prefe:rably of chrome-nickel steel) at surFace 14, e.g. by bondiny. Again body 17 works in the ultrasound thickness mode. An ultrasound ~ave US excited by the piezoceramic vibrator 17 is reflected at the parabolic reflector surface 14 and is focused into focal point F2, i.e. into the vicinity of the center of the disc-shaped workîng plate 16. As a consequence, the liquid on working plate li 16 is atomized to ~orm an aerosol.
; In the embodiment shown in Fig. 3, a lower surface 23 ; of a disc-shaped base plate 22 of a metal body 21 is designed as ¦
a plane circular area. The opposite side is designed as a para- ¦
' bolic reflector surface 24. The base plate 22 becomes a neck 25 and a subsequently disc-shaped enlargement serviny as working ¦ plate 26 above the parabolic reflector sur~ace 24 in the vicinity o~ the symmetry axis 30. This working plate 26 has a planar cen-tral portion 28 and a conical side or wall portion 29. The whole resonance system is symmetrical with respect to symmetry axis 30.
A piezoceramic vibrator 27 is o~ circular or cylindrical shape and is cemented and coupled to the plane base surface 23 as shown An ultrasound wave USl excited by the thickness vibrator 27 is refl~cted at the parabolic reflector surface 24 as well as at khe boundary surface 23 between the thickness vlbrator 27 and the base plate 22. It is focused toward the center o~ the disc-shaped working plate 26. In this embodiment, the ~ocal point F3 of the ultrasonic waves is therefore reflected by the interface 23 to a point behind the parabolic surface 24. In other words: In this embodiment focal point F3 of ultrasound wave USl and location of atomization are located at the same side of plane surFace 2~.
As the ultrasound waves are re~lected at the boundary surface between the thickness v~brator 27 and the base plate 22, interFerence phenomena and Deam dislocations occur which lead to Il ' ~;?
~3~7~
20365~2832 first portion of the respective ultrasound wave penetrates the liquid applied to the working sur~ace 26; a second portion proceeds as a surface wave in -the direction toward the rim 31 of the disc; a third part is reflected at the boundary surface. A
portion of the reflected third component is reflected by the bottom wall 29 of working plate 26 to the rim 31, as shown in dashed lines. A circular ring-shaped notch 33, preferably on the underside of the disc wall, in the vicinity of the disc rim 31 shields the disc rim 31 against the ultrasound wave, -thereby calming down the liquid located on the working plate 26 in the vicinity of the rim.
Instead of using a rim 33, the outer portion of wal' 29 may have a thickness different from the inner portion thereof.
Another possibility for calming down the liquid without using a rim 33 resides in a structure wherein the rim 33 is disposed in an obtuse angle with respect to the underside o:E wall 29.
For a working plate 26 holding ahout 15 microliters of a liquid for atomizing, it has been found that the plate diameter should be about three times the wavelength of the u:Ltrasouncl wave US in the body 21, the neck 25 and the central portion 28 should have a diameter of about one wavelength, and the neck 25 should have a height of about one wavelength; the base plate 22 should have a thickness of twice the wavelength, and the diameter of the base area 23 should be about t~n times the wavelength. The thick~
ness of the piezoceramic vibrator 27 should preferably correspond to approximately one-half the wavelength of the excited ultrasound wave in the thickness vibrator 27. The droplets generated by such a system may easily pass into the lungs of a person or patient.
5~
20365~-2832 While the forms of the ultrasound resonance system described herein constitute preferred embodiments of the invention, it is to be understood that the invention is not limited to these precise forms of assembly, and that a variety of changes may be made therein without departing from the scope of the invention.
- 8a -
a. Field of Invention This invention pertains to devices for generating resonance vibrations in the ultrasonic-frequency range, and more particularly to a piezoelectrically excitable resonance system, which can be used to diffuse, spray or atomize liquids.
b. Description of the Prior Art One device for atomizing liquid described in United States Patent No. 3,9~4,896 (DE-A1 2,032,433) consists of a metal body having rotational symmetry, and a piezoceramic vibrator coupled to a base area of the metal body. The metal body o~ this resonance system designed for bending excitation has three regions, namely, a disc shaped base plate, a vibrating plate designating the working plate, and a stem which connects the base plate and the working plate and which coincides ~ith the axis o~ symmetry of the metal body. The working plate sexves, ~or instance, for containing a liquid. Liquids atomized with such a resonance system have droplet diameters which, generally, are not small enough to penetrate all the way into the lungs o~ a person. Such a resonance system is there~ore not very suitable ~or atomizing liquids used for inhalation purposes.
For improving the above-mentioned liquid atomizer/ it has been proposed to design the working plate as a concave mirror while the base plate is cone~shaped, and to connect it to the conical base plate via a neck having a special shape. Thereby, very small volumes of liquid (15 microliters or less~ can be . , . . ~ il ~
~75i~5 atomized by using thickness resonance excitation, without a mechanical droplet filter, with a small electric excitation power and without coupling through a liquid medium, - la -to ~orm droplets with a dlameter smaller than or equa:L to 40 micrometers. The vibration frequency o~ this resonance system is in the megahertz range. ~ 3 ~ 7 OBJECTIVES AND SUMMARY OF THE INVENTION
It is an object of the invention tn provide an improved resonance system which requires a small electric excitation power, and in which droplets can be generated which have diameters smaller than 15 micro~eters. Droplets of this size penetrate into lungs easier than droplets of larger diameters.
According to the invent;on a piezoceramic resonance system comprises a resonance vibrator attached to a base plate having a parabolic cover or re~lector surface opposite a base area, and a working plate which is disc or shell-shaped. The center of the working plate is located at the focal point or in the vicinity of the focal point of the parabolic cover or reflector surface. PARABOLIC REFLE~TOR SURFACE is understood to mean within the scope of the invention, a surface which reflects incident ultrasonic waves toward a focal point. Such a surface may be approximated by a spherical surface or a surface generated by a paraboloid of ring-shaped subsurfaces (i~e., a plurality of truncated cone surfaces with different cone aperkure angles).
Reflection toward the ~ocal polnt may be direct or via the base plate, as will become more obvious later.
In a resonance system designed in this manner, the ultrasonic waves generated by the plezoceramic vibrator in a direction transversal to a major axis of the vibrator are in- 1 jected into the metal body. They are reflected at the parabolic reflector surface o~ the base p~ate and are ~ocused through the neck into the region of the worklng plate. Since the ultrasonic waves strike the working plate at an angle of inclination7 part of these sound waves is reflected in the direction of the rim ~L3~7~S~ i of the working plate or proceeds as a surface wave in the direc-tion of the rim. Thereby, a uniform distribution of the liquid to be atomized on the working plate and a uniform atomization over the entire atomizing time are obtained. In addltion, the liquid surface is located in the vicinity of the optimum atomizing point during the entire atomizing operation. Consequently, devices can be produced with an excitation power smaller than or equal to 20 W, in which more than 50% of the atomized liquid comprises droplets of 15 micrometers or less. Typically, the most frequent droplets may have a diameter smaller than or equal to 5 micrometers which is excellent for inhalation purposes. Furthermore, a given reso-nance frequency may be obtained since manufacturing tolerances of the resonance system may easily be controlled.
In a further embodiment of the invention, the metal body of the resonance system can be designed so that the base surface of the base plate is a circular ring and the base plate includes a transition into a conical neck which passes through the opening of the circular ring and extends above the base plate. Thereby, a relatively compact design is obtained for the resonance system. In this latter case, the piezoceramic thlckness vibrator has likewise the form of a circular ring.
In this embodiment, the workin0 plate may be integrated directly in the neck, the neck being designed as a truncated cone with a dise or shell-shaped depression or cavity at the tapered end. In this embodiment, the focal point of the ultrasonic waves can be placed in the cavity of the cone apex and thereby directly in the liquid to be atomized.
The resonator may also be designed so that the conical neck is provided at the tapered end with an enlargement to form the disc-shaped working plate. This makes it possible to atomize a larger quantity of liquid.
A particularly advantageous embodiment of the metal Ii ;~
~3~555 body comprises a base plate which changes into the neck supportiny the disc-shaped working plate on the side of the parabolic cover surface in the vicinlty of the axis of symmetryq In this embodi-ment, the ultrasonic waves are reflected twice before they strike the working plate. Interference effects, beam offsets (see German !
periodical "Materialprufung", 1965, pages 281 et al.) and re-entrance of the ultrasonic waves into the piezoceramic vibrator associated with this double reflection lead to parallel beam displacements9 whereby the feeding or coupling of the ultrasound into the liquid to be atomized is improved. This can be further improved by a special design of the working plate. This design consists in that the side portion of the disc-shaped working plate forms a conical surface. The transition zone between the neck and the disc-shaped working plate and the inclination of the side part relative to the middle part of the disc-shaped working plate are chosen so that sound waves reflected at the disc-shaped working plate are directed into the side part and then back to the liquid-plate interface. These multiple re~lections improve the efficiency of the resonance system.
The dimensions of the resonance system depend on the velocity of sound in the metal body, which preFerab~y consists of chrome-nickel steel, and on the desired ~requency which should be in the most advantageous transmission range o~ thé piezoceramic thickness vibrator. Since the continuous atomiza'cion of a liquid is preferably accomplished with standing ultrasonic waves, the ultrasound travel distance in the metal body should be a multiple of half a wavelength. For example, the ultasound travel distance may be 6 to 28 times its hal~ wavelength.
In view o~ the design with double reflec'cion o~ the ultrasonic waves, the thickness o~ the base plate should be about twice the ultrasound wavelength 9 and the diameter o~ the disc-shaped working plate should be about three times this wavelength.
1 ~
~30~5S~ 20365-2832 The diameter of the base area of the disc-shaped base plate should be approximately ten -times the wavelenyth. The height of the neck, i.e. the distance between the apex of the parabolic cover surface and the center of the disc-shaped working plate, should advantageously correspond to one wavelength.
According to a broad aspect of the invention there is provided a piezoelectrically excitable resonance system or atomizing a liquid, comprising: a metal body with rotational symmetry and capable of vibrating, said body including a disc-shaped base plate having a reflector surface with a focal point, a working plate disposed at least in the vicinity of said focal point for holding said liquid, and a neck connecting the working plate to the base plate; and a piezoceramic vibrator which is coupled to a plane base surface of the base plate perpendicular to the axis of symmetry, said piezoceramic vibrator operating as a thickness resonance vibrator.
BRIEF DESCRIPTIOW OF THE FIGURES
Figure 1 shows a resonance system according to theinvention wi-th a si.ngle reflection, and with a working plate being integral with the neck;
Figure 2 shows a resonance system according to the invention with a single reflection, and with a working plate being formed at the neck as a disc-like member; and Figure 3 shows an embodiment according to the inven-tion in which the ultrasound waves are reflected twice before they strike a disc-shaped working plate adjacent -to -the neck~
".
~., jl ~3~ 0365 2832 DETAILED DESCR TION OF TH:E DRAWING
Figure 1 shows a vibrating or resonance system wh.ich consists of a metal body 1 with rota-tional symmetry, preferably made out of chrome-nickel steel, and a piezoceramic vibrator 7.
The axis of symmetry is designated 10~ The vibrator 7 generates ultrasonic waves in a direction transversal to its major axis, upon excitation in response to an AC signal (-thickness excitation).
Geometrically, the one-piece metal body 1 may be considered as an annular member which is penetrated by a cone with a paraboloidal bottom surface, the annular par-t and the cone having the same axis 10 of symmetry and the same outside diameter~ Thus, this metal body 1 has a disc-shaped base plate 2 with a planar base surface 3 extending perpendicularly to the axis 10 of rotation and a parabolic reflector surface 4 opposite thereto~ The body 1 further includes a conically tapered neck 5 which pene-- 5a -,,, ,~. .
trates the annular base sur Face ~ and reaches beyond lts plarle.
The neck 5 is designed at the acutely tapered end with a dlsc or shell-shaped depression 6. The depression 6 forms the working ' plate o~ the resDnance system and is designed ~or receivlng a li-i quid to be atomized. The center of the depression 6 is located at the focal point Fl of surface 4 or in the proximity the~eof. The piezoceramic ultrasownd transducer or vibrator 7 of annular confi-guration is attached or coupled to the planar base surface 3 which is arranged vertically with respect to the symmetry axis 10. The transducer 7 is positioned symmetrically with respect to axis 10.
During operation it works in the so-called thickness resonance excitation mode, as is conventional in ultrasound techniques.
An ultrasound wave US generated by the piezoceramic vlbrator 7 upon electrical excitation is propagated into body 2, is reflected at the parabolic re~lector surface 4 and is thereby focused in the direction toward the shell-shaped depression 6. In the focal point Fl, i.e. basically in the entire region of depression 6, wave US leads to an atomization o~ the liquid, thereby generating a multiplicity o~ droplets having a very small diameter, such as 15 or 5 micrometers or even less.
In the embodiment o~ Fig 2, the resonance system is similar to the embodiment of Fig. 1, i.e. it comprLses a one-piece metal bocly 11 of rotakional symmetry ~ith respect to an axis 2û. The body 11 consists of a disc-shaped base plate 12 with a planar annular base surface 13, a parabolic reflector sur~ace 14 at the opposite side thereof, and a conically tapered neck 15.
Again the neck 15 extends beyond the surface 13. The working plate is provided here by a disc-shaped enlargement or member 16 which is ~ormed at the acutely tapered end of the neck 15, as shown, at or near the focal point F2 of surface 14 The disc-shaped part 16 has a planar middle portion I6' and a conical side portion or side wall 16~'.
I .",. ,~
1 3 075 S ~ !
The ~esonance system is exclted by eneryizing a pie~oceram:Lc rirly body 17 which is coupled or cemented to the body 11 (prefe:rably of chrome-nickel steel) at surFace 14, e.g. by bondiny. Again body 17 works in the ultrasound thickness mode. An ultrasound ~ave US excited by the piezoceramic vibrator 17 is reflected at the parabolic reflector surface 14 and is focused into focal point F2, i.e. into the vicinity of the center of the disc-shaped workîng plate 16. As a consequence, the liquid on working plate li 16 is atomized to ~orm an aerosol.
; In the embodiment shown in Fig. 3, a lower surface 23 ; of a disc-shaped base plate 22 of a metal body 21 is designed as ¦
a plane circular area. The opposite side is designed as a para- ¦
' bolic reflector surface 24. The base plate 22 becomes a neck 25 and a subsequently disc-shaped enlargement serviny as working ¦ plate 26 above the parabolic reflector sur~ace 24 in the vicinity o~ the symmetry axis 30. This working plate 26 has a planar cen-tral portion 28 and a conical side or wall portion 29. The whole resonance system is symmetrical with respect to symmetry axis 30.
A piezoceramic vibrator 27 is o~ circular or cylindrical shape and is cemented and coupled to the plane base surface 23 as shown An ultrasound wave USl excited by the thickness vibrator 27 is refl~cted at the parabolic reflector surface 24 as well as at khe boundary surface 23 between the thickness vlbrator 27 and the base plate 22. It is focused toward the center o~ the disc-shaped working plate 26. In this embodiment, the ~ocal point F3 of the ultrasonic waves is therefore reflected by the interface 23 to a point behind the parabolic surface 24. In other words: In this embodiment focal point F3 of ultrasound wave USl and location of atomization are located at the same side of plane surFace 2~.
As the ultrasound waves are re~lected at the boundary surface between the thickness v~brator 27 and the base plate 22, interFerence phenomena and Deam dislocations occur which lead to Il ' ~;?
~3~7~
20365~2832 first portion of the respective ultrasound wave penetrates the liquid applied to the working sur~ace 26; a second portion proceeds as a surface wave in -the direction toward the rim 31 of the disc; a third part is reflected at the boundary surface. A
portion of the reflected third component is reflected by the bottom wall 29 of working plate 26 to the rim 31, as shown in dashed lines. A circular ring-shaped notch 33, preferably on the underside of the disc wall, in the vicinity of the disc rim 31 shields the disc rim 31 against the ultrasound wave, -thereby calming down the liquid located on the working plate 26 in the vicinity of the rim.
Instead of using a rim 33, the outer portion of wal' 29 may have a thickness different from the inner portion thereof.
Another possibility for calming down the liquid without using a rim 33 resides in a structure wherein the rim 33 is disposed in an obtuse angle with respect to the underside o:E wall 29.
For a working plate 26 holding ahout 15 microliters of a liquid for atomizing, it has been found that the plate diameter should be about three times the wavelength of the u:Ltrasouncl wave US in the body 21, the neck 25 and the central portion 28 should have a diameter of about one wavelength, and the neck 25 should have a height of about one wavelength; the base plate 22 should have a thickness of twice the wavelength, and the diameter of the base area 23 should be about t~n times the wavelength. The thick~
ness of the piezoceramic vibrator 27 should preferably correspond to approximately one-half the wavelength of the excited ultrasound wave in the thickness vibrator 27. The droplets generated by such a system may easily pass into the lungs of a person or patient.
5~
20365~-2832 While the forms of the ultrasound resonance system described herein constitute preferred embodiments of the invention, it is to be understood that the invention is not limited to these precise forms of assembly, and that a variety of changes may be made therein without departing from the scope of the invention.
- 8a -
Claims (12)
1. A piezoelectrically excitable resonance system for atomizing a liquid, comprising:
a metal body with rotational symmetry and capable of vibrating, said body including a disc-shaped base plate having a reflector surface with a focal point, a working plate disposed at least in the vicinity of said focal point for holding said liquid, and a neck connecting the working plate to the base plate; and a piezoceramic vibrator which is coupled to a plane base surface of the base plate perpendicular to the axis of symmetry, said piezoceramic vibrator operating as a thickness resonance vibrator.
a metal body with rotational symmetry and capable of vibrating, said body including a disc-shaped base plate having a reflector surface with a focal point, a working plate disposed at least in the vicinity of said focal point for holding said liquid, and a neck connecting the working plate to the base plate; and a piezoceramic vibrator which is coupled to a plane base surface of the base plate perpendicular to the axis of symmetry, said piezoceramic vibrator operating as a thickness resonance vibrator.
2. The resonance system according to claim 1, wherein said base plate has a base surface shaped as a circular ring and makes a transition into a conical neck which passes through the opening of the circular ring beyond the base surface.
3. The resonance system according to claim 2, wherein said neck is formed as a truncated cone tapered at an acute angle and having a disc-shaped depression.
4. The resonance system according to claim 2, wherein the conical neck makes a transition to an enlarged disc-shaped working plate.
5. The resonance system according to claim 1, wherein the disc-shaped base plate makes a transition to the neck supporting the disc-shaped working plate on the side of the parabolic surface in the vicinity of the axis of symmetry.
6. The resonance system according to claim 5, wherein the disc-shaped working plate has a conical side park and the transition region between the neck and the disc-shaped working plate as well as the inclination of the side part relative to the central part of the disc-shaped working plate are arranged and constructed for repeated reflections.
7. The resonance system according to claim 6, wherein the side part is provided with a circular notch in the vicinity of the rim of the disc.
8. The resonance system according to claim 5, wherein the thickness of the disc-shaped base plate is about twice the wavelength of the ultrasound in the base plate.
9. The resonance according to claim 5 7 wehrein the diameter of the disc-shaped working plate is about three times the ultrasound wavelength.
10. The resonance system according to claim 5, wherein the diameter of the base area of the base plate is approximately ten times the ultrasound wavelength.
11. The resonance system according to claim 5, wherein the diameter of the neck is approximately equal to one ultrasound wavelength.
12. The resonance system according to claim 5, wherein the height of the neck corresponds approximately to one wavelength of the ultrasound.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19873724629 DE3724629A1 (en) | 1987-07-22 | 1987-07-22 | PIEZOELECTRICALLY REQUIRED RESONANCE SYSTEM |
| DEP3724629.1 | 1987-07-22 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1307555C true CA1307555C (en) | 1992-09-15 |
Family
ID=6332325
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000572482A Expired - Fee Related CA1307555C (en) | 1987-07-22 | 1988-07-20 | Piezoelectrically excitable resonance system |
Country Status (6)
| Country | Link |
|---|---|
| US (1) | US4888516A (en) |
| EP (1) | EP0300319B1 (en) |
| JP (1) | JP2543493B2 (en) |
| AT (1) | ATE129651T1 (en) |
| CA (1) | CA1307555C (en) |
| DE (2) | DE3724629A1 (en) |
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| US5152456A (en) * | 1989-12-12 | 1992-10-06 | Bespak, Plc | Dispensing apparatus having a perforate outlet member and a vibrating device |
| US5938117A (en) | 1991-04-24 | 1999-08-17 | Aerogen, Inc. | Methods and apparatus for dispensing liquids as an atomized spray |
| US6629646B1 (en) | 1991-04-24 | 2003-10-07 | Aerogen, Inc. | Droplet ejector with oscillating tapered aperture |
| US5449502A (en) * | 1992-12-30 | 1995-09-12 | Sanden Corp. | Sterilizing apparatus utilizing ultrasonic vibration |
| JPH0824739A (en) * | 1994-06-29 | 1996-01-30 | Siemens Ag | Ultrasonic wave spray |
| CA2215331C (en) * | 1995-03-14 | 2002-01-22 | Siemens Aktiengesellschaft | Ultrasonic atomizer device with removable precision dosating unit |
| US5970974A (en) * | 1995-03-14 | 1999-10-26 | Siemens Aktiengesellschaft | Dosating unit for an ultrasonic atomizer device |
| US5758637A (en) | 1995-08-31 | 1998-06-02 | Aerogen, Inc. | Liquid dispensing apparatus and methods |
| US6014970A (en) * | 1998-06-11 | 2000-01-18 | Aerogen, Inc. | Methods and apparatus for storing chemical compounds in a portable inhaler |
| US6205999B1 (en) | 1995-04-05 | 2001-03-27 | Aerogen, Inc. | Methods and apparatus for storing chemical compounds in a portable inhaler |
| US6085740A (en) | 1996-02-21 | 2000-07-11 | Aerogen, Inc. | Liquid dispensing apparatus and methods |
| US6782886B2 (en) | 1995-04-05 | 2004-08-31 | Aerogen, Inc. | Metering pumps for an aerosolizer |
| DE19533370C2 (en) * | 1995-09-09 | 1999-10-28 | Wilk Bernd Ulrich | Process and plant for the biological mineralization of sludge in standing and flowing waters |
| AU750458B2 (en) | 1998-03-03 | 2002-07-18 | Sensotech Ltd. | Ultrasonic transducer |
| DE19924098A1 (en) * | 1999-05-26 | 2000-12-07 | Boehringer Ingelheim Pharma | Stainless steel canister for propellant-powered MDIs |
| US6739333B1 (en) * | 1999-05-26 | 2004-05-25 | Boehringer Ingelheim Pharma Kg | Stainless steel canister for propellant-driven metering aerosols |
| US6235177B1 (en) | 1999-09-09 | 2001-05-22 | Aerogen, Inc. | Method for the construction of an aperture plate for dispensing liquid droplets |
| US7100600B2 (en) | 2001-03-20 | 2006-09-05 | Aerogen, Inc. | Fluid filled ampoules and methods for their use in aerosolizers |
| US7971588B2 (en) | 2000-05-05 | 2011-07-05 | Novartis Ag | Methods and systems for operating an aerosol generator |
| US6948491B2 (en) | 2001-03-20 | 2005-09-27 | Aerogen, Inc. | Convertible fluid feed system with comformable reservoir and methods |
| US8336545B2 (en) | 2000-05-05 | 2012-12-25 | Novartis Pharma Ag | Methods and systems for operating an aerosol generator |
| US6543443B1 (en) | 2000-07-12 | 2003-04-08 | Aerogen, Inc. | Methods and devices for nebulizing fluids |
| US6546927B2 (en) | 2001-03-13 | 2003-04-15 | Aerogen, Inc. | Methods and apparatus for controlling piezoelectric vibration |
| US6550472B2 (en) | 2001-03-16 | 2003-04-22 | Aerogen, Inc. | Devices and methods for nebulizing fluids using flow directors |
| US6732944B2 (en) | 2001-05-02 | 2004-05-11 | Aerogen, Inc. | Base isolated nebulizing device and methods |
| US6554201B2 (en) | 2001-05-02 | 2003-04-29 | Aerogen, Inc. | Insert molded aerosol generator and methods |
| US7677467B2 (en) | 2002-01-07 | 2010-03-16 | Novartis Pharma Ag | Methods and devices for aerosolizing medicament |
| MXPA04006629A (en) | 2002-01-07 | 2004-11-10 | Aerogen Inc | Devices and methods for nebulizing fluids for inhalation. |
| ES2603067T3 (en) | 2002-01-15 | 2017-02-23 | Novartis Ag | Methods and systems for operating an aerosol generator |
| ES2572770T3 (en) | 2002-05-20 | 2016-06-02 | Novartis Ag | Apparatus for providing spray for medical treatment and methods |
| US8616195B2 (en) | 2003-07-18 | 2013-12-31 | Novartis Ag | Nebuliser for the production of aerosolized medication |
| US7946291B2 (en) | 2004-04-20 | 2011-05-24 | Novartis Ag | Ventilation systems and methods employing aerosol generators |
| BRPI0611198B1 (en) * | 2005-05-25 | 2018-02-06 | Aerogen, Inc. | VIBRATION SYSTEMS AND METHODS |
| DE102006033372B4 (en) * | 2006-02-17 | 2010-04-29 | Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. | Ultrasonic actuator for cleaning objects |
| FR2898468B1 (en) * | 2006-03-15 | 2008-06-06 | Lvmh Rech | PIEZOELECTRIC ELEMENT SPRAY DEVICE AND USE THEREOF IN COSMETOLOGY AND PERFUMERY. |
| JP2008006644A (en) * | 2006-06-28 | 2008-01-17 | Fujifilm Corp | Mist discharge head, and image forming apparatus and liquid discharge apparatus with the head |
| WO2009155245A1 (en) | 2008-06-17 | 2009-12-23 | Davicon Corporation | Liquid dispensing apparatus using a passive liquid metering method |
| RU2577582C1 (en) * | 2014-10-20 | 2016-03-20 | Федеральное государственное бюджетное учреждение науки Институт механики Уральского отделения Российской академии наук | Plate-type fluid sprayer |
| CN111841205A (en) * | 2020-06-24 | 2020-10-30 | 重庆工程职业技术学院 | Centrifugal jet atomization and ultrasonic atomization combined method with water-saving characteristic |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE883358C (en) * | 1942-03-22 | 1953-07-16 | Siemens Ag | Device for the treatment of substances, in particular liquids, by means of ultrasonic vibrations |
| DE1425897A1 (en) * | 1964-10-20 | 1969-02-06 | Lierke Dipl Phys Ernst Guenter | Device for atomizing liquids with ultrasound |
| FR1545920A (en) * | 1967-10-06 | 1968-11-15 | Siderurgie Fse Inst Rech | Ultrasonic sounding device |
| US3904896A (en) * | 1970-06-30 | 1975-09-09 | Siemens Ag | Piezoelectric oscillator system |
| SU434623A1 (en) * | 1972-09-07 | 1974-06-30 | М. В. Королев , О. Г. Галкин | ULTRASONIC PIEZOELECTRIC CONVERTER |
| US3904894A (en) * | 1974-07-24 | 1975-09-09 | Gen Motors Corp | Circuit for producing an output signal during the period between the pulses of repeating time displaced pulse pairs |
| DE2557958B2 (en) * | 1975-12-22 | 1981-01-29 | Bosch-Siemens Hausgeraete Gmbh, 7000 Stuttgart | Piezoelectric ultrasonic liquid atomizer |
| US4384231A (en) * | 1979-05-11 | 1983-05-17 | Hitachi, Ltd. | Piezoelectric acoustic transducer with spherical lens |
| DE3112339A1 (en) * | 1980-04-12 | 1982-02-25 | Battelle-Institut E.V., 6000 Frankfurt | Device for atomising liquids |
| US4474326A (en) * | 1981-11-24 | 1984-10-02 | Tdk Electronics Co., Ltd. | Ultrasonic atomizing device |
| DE3616713A1 (en) * | 1986-05-20 | 1987-11-26 | Siemens Ag | ULTRASONIC MHZ SWINGERS, IN PARTICULAR FOR LIQUID SPRAYING |
-
1987
- 1987-07-22 DE DE19873724629 patent/DE3724629A1/en not_active Withdrawn
-
1988
- 1988-07-11 AT AT88111066T patent/ATE129651T1/en not_active IP Right Cessation
- 1988-07-11 EP EP88111066A patent/EP0300319B1/en not_active Expired - Lifetime
- 1988-07-11 DE DE3854634T patent/DE3854634D1/en not_active Expired - Fee Related
- 1988-07-20 JP JP63182760A patent/JP2543493B2/en not_active Expired - Fee Related
- 1988-07-20 CA CA000572482A patent/CA1307555C/en not_active Expired - Fee Related
- 1988-07-21 US US07/222,266 patent/US4888516A/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| EP0300319A3 (en) | 1990-05-09 |
| JPS6451162A (en) | 1989-02-27 |
| JP2543493B2 (en) | 1996-10-16 |
| EP0300319A2 (en) | 1989-01-25 |
| DE3724629A1 (en) | 1989-02-02 |
| EP0300319B1 (en) | 1995-11-02 |
| ATE129651T1 (en) | 1995-11-15 |
| US4888516A (en) | 1989-12-19 |
| DE3854634D1 (en) | 1995-12-07 |
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| Date | Code | Title | Description |
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| MKLA | Lapsed |