close

Вход

Забыли?

вход по аккаунту

?

DESCRIPTION JP2008263419

код для вставкиСкачать
Patent Translate
Powered by EPO and Google
Notice
This translation is machine-generated. It cannot be guaranteed that it is intelligible, accurate,
complete, reliable or fit for specific purposes. Critical decisions, such as commercially relevant or
financial decisions, should not be based on machine-translation output.
DESCRIPTION JP2008263419
The present invention relates to a high-performance ultrasonic transducer which is not affected
by moisture absorption by subjecting a porous ceramic body that is susceptible to moisture
absorption to a high sensitivity, and an ultrasonic flowmeter using the same. Intended to be
provided. An acoustic matching body 10 is formed of a ceramic porous body provided with a
resin film 13 having water repellency by vapor deposition treatment so as to have a
predetermined thickness on the surface forming the skeleton of the ceramic porous body. Due to
the nature of the surface of the ceramic porous body susceptible to moisture absorption covered
with the resin film 13 and not exposed, the moisture absorption of the acoustic matching body is
suppressed even if it is left under temperature change or high temperature and high humidity,
and good output sensitivity can be maintained. It becomes. In addition, since the surface of the
hard and brittle ceramic porous body is covered with a flexible resin film to cover the brittleness,
there is no concern that a part of the ceramic porous body may be chipped or dusted. [Selected
figure] Figure 2
Acoustic matching body, ultrasonic transducer, and ultrasonic flow meter
[0001]
The present invention provides an acoustic matching body, an ultrasonic transducer using the
same, and an ultrasonic transducer for transmitting ultrasonic waves into a fluid (particularly
gas) or receiving ultrasonic waves propagating through the fluid. The present invention relates to
an ultrasonic flowmeter using a wave device.
[0002]
14-04-2019
1
Conventionally, in this type of ultrasonic transducer, as shown in, for example, FIG. 8, an acoustic
matching body 50 including a piezoelectric body and being incorporated in an ultrasonic
transducer for transmitting or receiving ultrasonic waves is provided. A porous body 53 made of
a framework material 82 having voids 51, a low porosity layer 54 having a porosity lower than
that of the porous body in at least a part of the surface to be measured, or the surface of the
porous body or The binder diffusion layer is formed in at least a part of the inside (for example,
see Patent Document 1).
JP 2003-111195 A
[0003]
However, in the above-mentioned conventional configuration, due to the nature of the porous
body, it is easy to absorb moisture, condensation occurs when it changes temperature during
transportation, etc., or when it is left under high temperature and high humidity. An ultrasonic
transducer provided with this acoustic matching body reduces the propagation efficiency of
ultrasonic waves emitted to, for example, gas by causing reflection and diffusion, and changing
the sound velocity and density of the acoustic matching body. When the ultrasonic flow velocity
flowmeter is mounted, the measurement accuracy of the flow velocity and flow rate is lowered. In
addition, the porous body used as the acoustic matching body weakens in strength when the
density is reduced in order to transmit and receive ultrasonic waves more efficiently, so that the
porous body may be chipped during transportation, dust generation, and other devices. There
was a concern that would have an adverse effect.
[0004]
The present invention solves the above-mentioned conventional problems, and by forming a film
having water repellency on a skeleton formed of a porous body that easily absorbs moisture, it is
a highly sensitive and high-performance acoustic wave that is not affected by moisture
absorption. An object of the present invention is to provide a matching body, an ultrasonic
transducer or an ultrasonic flowmeter using the same.
[0005]
In order to solve the above problems, an ultrasonic transducer according to the present invention
is an acoustic matching body that includes a piezoelectric body and is incorporated in an
ultrasonic transducer that transmits or receives ultrasonic waves, and is formed of a porous
14-04-2019
2
body. An acoustic matching body in which a water-repellent film is formed on a skeleton is used.
[0006]
According to the above configuration, since the acoustic matching body has a water repellent
film formed on the porous skeleton, the porous skeleton that is easily hygroscopic in nature is
not exposed, and it is left under temperature change or high temperature and high humidity.
Even if it does, the moisture absorption of the acoustic matching body is suppressed, and a good
output can be maintained.
Further, since the porous body has a thin and fragile skeleton, forming a water-repellent resin
film having flexibility on the surface of the skeleton reduces the chipping and dusting properties
of the porous body.
[0007]
The acoustic matching body, the ultrasonic transducer, and the ultrasonic velocity flow meter
according to the present invention suppress the moisture absorption of the acoustic matching
body due to the temperature change or the high temperature and high humidity leaving the
output of the ultrasonic transducer. Can be easily maintained, and the porous body can be
protected. When this is used for a flow rate flow meter, measurement accuracy can be improved.
[0008]
According to a first aspect of the present invention, there is provided an acoustic matching body
including a piezoelectric body and incorporated in an ultrasonic transducer for transmitting or
receiving an ultrasonic wave, wherein a water repellent film is formed on a skeleton formed of a
porous body. By forming an acoustic matching body, the acoustic matching body has a water
repellent film formed on the skeleton of the porous body, so that the porous skeleton, which is
likely to absorb moisture by nature, is not exposed, and temperature changes or high
temperature and high humidity Even if left under, the moisture absorption of the acoustic
matching body is suppressed, and a good output can be maintained.
In addition, since the porous body has a thin and fragile skeleton, the chipping and dusting
properties of the porous body can be reduced by forming a water-repellent resin film having
14-04-2019
3
flexibility on the surface of the skeleton.
[0009]
In the second aspect of the present invention, the porous body can be formed to be lightweight
and inexpensive at a low cost by using the acoustic matching body according to claim 1 in which
the porous body is a ceramic porous body.
[0010]
In the third invention, the film having water repellency can be uniformly formed on the porous
skeleton by using the acoustic matching body according to claim 1 formed by vapor deposition.
[0011]
In the fourth aspect of the invention, the water-repellent film is formed by vapor deposition using
the acoustic matching body according to claim 3, wherein the material is vaporized in the
monomer state and becomes a polymer when the porous body is attached. Since a resin material
that is vaporized in the medium vacuum atmosphere is a monomer and becomes a polymer when
attached to the ceramic porous body, the resin material in the vaporized state is a small particle
of monomer and enters into a narrow gap and adheres. When it is formed, it becomes a strong
polymer and forms a film, so that the pore diameter of the ceramic porous body can penetrate
into pores of 1 μm or less and can be formed to a predetermined thickness up to the inside of
the porous body.
In addition, precise control of thickness is possible, and by using a thin film without pinholes, the
acoustic characteristics of the ultrasonic transducer are affected as little as possible and stable
characteristics are possible. .
[0012]
The fifth invention is provided with an acoustic film on the outer wall surface of the acoustic
matching body top portion, and the acoustic film is formed by transferring to a porous body after
printing on another base material. The porosity of the vicinity of the surface opposite to the fluid
to be measured is lower than the porosity of the vicinity of the surface of the acoustic matching
body formed of the ceramic porous body, and is closer to a flat surface. The vibration of the
acoustic matching body vibrated by the vibrator vibrates the fluid to be measured (transmission),
and conversely, the vibration of the fluid to be measured is vibrated (reception) efficiently.
14-04-2019
4
become able to.
[0013]
In the sixth invention, by using the acoustic matching body according to claim 5, wherein the
other base material is a mold release film, the porous body can be more easily released without
applying stress, and the acoustic film is a porous body. A smooth acoustic film can be formed
without falling off in the void portion formed in the above, and the vibration of the acoustic
matching body vibrated by the vibrator vibrates the fluid to be measured (transmission), and
conversely, the fluid to be measured Vibration of the acoustic matching body can be made to
efficiently vibrate (reception).
[0014]
In the seventh invention, the porous body is to gelate in a mold a foam containing ceramic slurry
having at least one ceramic powder to obtain a gel-like porous molded body, and dry or degrease
the gel-like porous molded body The method for producing an acoustic matching body according
to claim 2 formed by a method including baking the gel-like porous molded body, the radical
polymerization of the monomers in the slurry results in the inside of the mold A polymer
network is formed to form a gel wet molded body, so that the flow process and solidification
process of the slurry are completely separated, and the particles are fixed in place, causing
nonuniformity and defects in the ceramic porous body. It is difficult to do, and it is possible to
obtain about 10 times or more strength against general pressure molding and cast molding, and
it becomes a uniform structure, and the density variation is also small. , Can respond with
complex shapes, it can also be increased light and strength.
Therefore, chipping of the ceramic porous body at the time of assembly and the like, and dusting
ability can be reduced, so that there is less concern for adversely affecting other devices.
Further, since a void can be formed also in the skeleton formed by the porous body, the
propagation efficiency of the vibration with the fluid to be measured can be improved by
reducing the density of the ceramic porous body.
[0015]
In the eighth invention, the porous body is a gel-like porous molded body obtained by gelation of
a ceramic slurry containing at least one ceramic powder and a void forming member in a mold.
14-04-2019
5
The method for producing an acoustic matching body according to claim 2, formed by a method
comprising drying or degreasing the gel and calcining the gel-like porous molded body, the
volume of the void is controlled by the void-forming member. As a result, the density of the
ceramic porous body can be stabilized.
[0016]
In a ninth aspect of the present invention, the water repellent membrane is formed by slicing a
porous body into a skeleton of a ceramic porous body formed in a rod shape by the
manufacturing method according to claim 7 and slicing into a predetermined shape. 9. By using
the acoustic matching body according to any one of items 1 to 8, the acoustic matching body is
repellent by vapor deposition so as to have a predetermined thickness on the surface forming the
skeleton of the ceramic porous body formed in a rod shape. After applying an aqueous resin film,
it is sliced into a predetermined shape, so that the strength of the ceramic porous body is greatly
increased by performing vapor deposition treatment in a relatively strong rod state, and the
predetermined shape is obtained. Can be used to prevent damage during slicing and assembly,
and can also reduce chipping and dusting of part of the acoustic matching body formed of the
ceramic porous body in the finished product state. , At the time of assembly, etc. Handling is
likely to be.
[0017]
The tenth invention comprises an acoustic matching body and a piezoelectric body, and the
acoustic matching body is an ultrasonic transducer having the acoustic matching body according
to any one of claims 1 to 9. The effects of the first to ninth inventions are obtained, and
ultrasonic transmission and reception capable of suppressing moisture absorption of the acoustic
matching body even when left under temperature change or high temperature and high
humidity, and maintaining good output. It can be a waver.
[0018]
According to an eleventh aspect of the present invention, there is provided an open-ended
cylindrical case, a piezoelectric body fixed to the open-ended cylindrical case top portion inner
wall surface, an acoustic matching body fixed to the open-ended cylindrical case top portion
outer wall surface, and the open-ended cylinder And a conductive terminal plate welded and
fixed to the support case, and the acoustic matching body is an ultrasonic transducer having the
acoustic matching body according to any one of claims 1 to 9, Even if the piezoelectric body does
not deteriorate due to the external environment, and the above-mentioned effects of the first to
ninth inventions are obtained, the acoustic matching body can be obtained even if it is left under
temperature change or high temperature and high humidity. It is possible to provide an
ultrasonic transducer capable of suppressing moisture absorption and maintaining a good
14-04-2019
6
output.
[0019]
The ultrasonic wave transmitting and receiving apparatus according to claim 10 or 11, wherein
the water repellent film is formed in a state in which the acoustic matching body is disposed in
close contact with at least the top outer wall surface of the case by close contact means. By
forming the waver, the acoustic matching body is integrated with the outer side of the top
portion of the case by the close-contact means and is more firmly joined, and peeling of the
acoustic matching body can be prevented.
[0020]
The thirteenth aspect of the present invention is the ultrasonic transducer according to claim 10
or 11, wherein the water repellent film is formed in a state in which at least the terminal plate
and the case are joined to each other. Thus, it is possible to protect the electric corrosion of the
metal which is likely to occur at the water accumulation portion which can be caused by the step
difference, etc., and to prevent the occurrence of rust and the like.
[0021]
A fourteenth aspect of the invention relates to a flow path through which a fluid to be measured
flows, a pair of ultrasonic transducers according to any one of claims 10 to 13, and ultrasonic
propagation time between the ultrasonic transducers. According to the ultrasonic flow velocity
flowmeter including the timing device, the effects and advantages of any one of the tenth to
thirteenth inventions described above can be obtained, and the reliability against temperature
change or high temperature and high humidity is improved. It is possible to provide an ultrasonic
flow velocity flowmeter aiming to improve the measurement accuracy with high reliability.
[0022]
Hereinafter, embodiments of the present invention will be described with reference to the
drawings.
The present invention is not limited by the present embodiment.
[0023]
14-04-2019
7
First Embodiment An example of an ultrasonic transducer configured using the acoustic
matching body of the present invention is shown in FIG.
In FIG. 1, the acoustic matching body is bonded to the piezoelectric body 3 with an adhesive
which is a bonded body 4 to form the ultrasonic transducer 1.
The piezoelectric body 3 is provided with opposing electrodes 5 and 6.
The electrodes are formed by heating and baking a conductive paste such as silver or gold.
The electrodes 5 and 6 and the electrode leads 7 and 8 are electrically joined by solder or silver
solder.
Hereinafter, the acoustic matching body will be described, and further, the porous body forming
the acoustic matching body will be described.
[0024]
FIG. 2 shows an enlarged sectional view of an essential part of the acoustic matching body
formed of the porous body according to the first embodiment of the present invention.
In FIG. 2, the acoustic matching body 10 measures the flow rate of the porous skeleton 11, the
void 12 formed by the skeleton, the water-repellent film 13 formed on the surface of the porous
skeleton 11, and the flow velocity. And an acoustic film 14 formed on the surface in contact with
the fluid to be measured.
[0025]
The porous body is preferably a ceramic porous body.
14-04-2019
8
In addition, it is preferable that the acoustic matching body 10 be configured to form the
acoustic film 14 on the ceramic porous body and the sound wave emitting surface.
[0026]
For example, the ceramic porous body includes ceramic particles constituting a ceramic matrix,
the ceramic matrix defines a plurality of voids 12, in the ceramic matrix, voids between ceramic
particles are formed, and the density is reduced. Can.
Further, due to the presence of the void portion and the void between the ceramic particles, the
skeleton of the ceramic matrix does not extend linearly, and provides a tortuous path to
ultrasonic waves. This reduces the propagation velocity of the ultrasound. Therefore, the porous
body 10 has the characteristics of low density and low sound velocity, and the ultrasonic
transducer using this as the acoustic matching layer has the propagation characteristics of
ultrasonic waves significantly improved.
[0027]
Here, the “void” refers to a portion recognized as a void when a ceramic matrix composed of a
plurality of ceramic particles is macroscopically observed (for example, with a microscope with a
magnification of about 20). The “inter-ceramic particle space” means a minute space formed
between particles constituting the ceramic matrix and specifically, small pores having a diameter
of 10 μm or less. Alternatively, the “void” may be a void formed by foaming the ceramic
slurry according to the method described later, and the “void between ceramic particles” may
be a void formed in the ceramic regardless of the presence or absence of foaming. It can be said
that
[0028]
In the acoustic matching body 10, in the porous body, it is preferable that the void portion has a
dimension such that the center value of the pore size distribution is in the range of 10 μm to
500 μm. When the first porous body has a void of such a size, the vibration generated by the
14-04-2019
9
piezoelectric body can be uniformly transmitted to the fluid to be measured.
[0029]
The ceramic matrix preferably comprises hard-to-sinter ceramics but may not contain hard-tosinter ceramics. The non-sinterable ceramic preferably accounts for 80 vol% of the ceramic
matrix, more preferably 90 vol%, and still more preferably 100 vol%.
[0030]
FIG. 3 shows a manufacturing process flow of the ceramic porous body used for the acoustic
matching body 10. The process comprises the steps of: grinding a non-sinterable ceramic; adding
an additive to the ceramic powder to form a slurry; introducing a bubble; introducing the slurry
into a mold; forming the slurry; and firing. Details will be described below.
[0031]
(Sintering-resistant ceramic pulverizing step) Pulverization of ceramic can be obtained by mixing,
pulverizing or the like with a ball mill, pot mill or the like. The average particle size of the
ceramic powder is not particularly limited, but is preferably 10 μm or less. When the ceramic
having an average particle diameter in this range is used, the powder dispersibility in the slurry
is improved, and the sinterability is also improved.
[0032]
(Slurrying Step of Ceramic Powder) In the ceramic slurry, water, an organic solvent, a mixed
solvent thereof, or the like can be used as a medium for suspending the ceramic powder.
Preferably water is used. In order to uniformly contain the ceramic powder in the ceramic slurry,
it is preferable to use a suitable dispersant. As a dispersing agent, a polycarboxylic acid-based
dispersing agent (anionic dispersing agent) can be used, and specifically, ammonium
polycarboxylate and sodium polycarboxylate can be used. Preferably, a dispersant having a large
change in slurry viscosity with the added amount of dispersant is used. The amount of the
dispersant used is preferably 5% by weight or less, more preferably 1% by weight or less, based
14-04-2019
10
on the weight of the ceramic powder.
[0033]
The ceramic slurry is removed before introducing the ceramic slurry bubbles, and the bubbles
are introduced while stirring the slurry. When bubbles are introduced into the ceramic slurry, a
gelling agent, and a polymerizable material comprising a monomer and a polymerization initiator
are added in order to form the desired shape. When a gelling agent is used, the slurry is gelled by
temperature control, pH control, and the like. Examples of the gelling agent include gelatin,
agarose, agar, sodium alginate and the like.
[0034]
When a polymerizable material is used, a monomer of the polymerizable material is used.
Specifically, monomers provided with one or more vinyl groups, allyl groups and the like can be
mentioned. When the slurry is composed of water or an aqueous solvent, it is preferable to use a
monofunctional or bifunctional polymerizable monomer. Moreover, when a slurry is comprised
with an organic solvent, it is preferable that it is a bifunctional polymerizable monomer. In
particular, when water is prepared as a solvent in the slurry, preferably at least one
monofunctional (meth) acrylamide and at least one difunctional (meth) acrylamide are used. Use
in combination. When the slurry is prepared with an organic solvent, preferably, at least two
difunctional (meth) acrylic acids are used in combination.
[0035]
When a monofunctional monomer or a bifunctional monomer is used, ammonium persulfate,
potassium persulfide and the like are preferable. Moreover, when using the functional group
monomer which has a 2 or more functional group, Preferably, an organic peroxide, a hydrogenperoxide compound, an azo or a diazo compound is used. Specifically, it is benzoyl peroxide.
[0036]
The introduced gas is preferably retained in the slurry as bubbles by a surfactant or the like. The
14-04-2019
11
surfactant is preferably added to the ceramic slurry prior to the introduction of air bubbles by
stirring or the like in the air bubble introduction step. Examples of the surfactant include anionic
surfactants such as alkyl benzene sulfonic acid and cationic surfactants such as higher alkyl
amino acids. Specifically, n-dodecylbenzene sulfonic acid, polyoxyethylene sorbitan monolaurate,
polyoxyethylene monooleate, polyoxyethylene nonylphenyl ether, polyoxyethylene lauryl ether,
and alkali metal salts such as sodium and potassium thereof It can be mentioned. In addition,
triethanolamine lauryl ether and the like and their halogenated salts, sulfates, acetates,
hydrochlorides and the like can be mentioned. Moreover, diethylhexyl succinic acid and its alkali
metal salt etc. can be mentioned.
[0037]
(Air Bubble Introduction Step) Air bubbles are introduced into the slurry produced as described
above. In the case of using a polymerizable material as the gelling material in this bubble
introducing step, it is preferable to add a polymerization initiator or a polymerization initiator
and a polymerization catalyst together with the polymerizable material. If a polymerization
catalyst is added, the time of the gelation step can be adjusted by the gelation temperature and
the addition amount thereof. Usually, when a polymerization catalyst is added, gelation
(polymerization) is rapidly started at around room temperature. Therefore, the use and type of
the polymerization catalyst are selected in consideration of the bubble introduction method, the
bubble introduction amount, and the like. As a polymerization catalyst, N, N, N ', N'- tetramethyl
ethylene diamine etc. can be mentioned, for example.
[0038]
(Slurry Forming Step) The cell-containing ceramic slurry thus prepared is injected into a forming
die or the like and gelated to form a gel-like porous formed body. The slurry is poured into a
cylindrical mold containing a bubble-containing ceramic slurry and subjected to a polymerization
reaction or a gelation reaction to solidify. When the slurry solidifies, the bubbles present in the
slurry are also stored in the gel-like body. As a result, the solidified body becomes porous, and a
gel-like porous molded body is obtained. It is demolded, dried, degreased and fired. Drying is
carried out to evaporate the water and solvent contained in the gel-like porous molded body. The
drying conditions (temperature, humidity, time, etc.) are appropriately adjusted according to the
type of solvent used for slurry preparation and the component (gelling agent or polymer)
constituting the skeleton of the gel porous molded body. Usually, the temperature is 20 ° C. or
more, preferably 25 ° C. or more and 80 ° C. or less, and more preferably 25 ° C. or more and
40 ° C. or less.
14-04-2019
12
[0039]
(Firing Step) Next, in order to remove the organic component from the dried product, the heating
is further performed at a high temperature. The temperature and time for degreasing are
adjusted according to the amount and type of organic component used. For example, in the case
of a gel-like porous molded body prepared from a slurry using methacrylamide and N, Nmethylenebisacrylamide as a material for gelation, degreasing is performed at 700 ° C. for 2
days.
[0040]
After degreasing, a firing step is performed. The conditions for firing are set in consideration of
the type of ceramic material used and the like. By these steps, the ceramic porous body 11 of the
present invention can be obtained.
[0041]
The ceramic porous body 11 is a porous body, and a plurality of voids exist. The voids are
preferably dispersed in the ceramic porous body 11. The voids may exist independently, may be
present continuously with other voids, and may be in communication with the outside. In the
acoustic matching body 10, it is preferable that the holes be continuously present.
[0042]
The porous ceramic body 11 as a whole has a porosity of 60% to 90% (here, the total porosity
including open pores and closed pores). It is preferable to have More preferably, it is 80% or
more and 90% or less. The total porosity is determined by the following formula (1).
[0043]
14-04-2019
13
Total porosity (%) = (1-bulk density / true density) x 100 (1) However, bulk density = weight of
sample / bulk volume of sample. True density, for example, an arbitrary amount of extremely
micronized sample is charged into a pycnometer, water is injected until a predetermined volume
is reached, and boiling is performed to eliminate voids, and from the relationship between weight
and volume, It can be asked. When the efficiency is 60% or less, the density 11 of the acoustic
matching body 1 becomes large, and when the pore diameter exceeds 90%, the mechanical
strength significantly decreases. The open porosity is more preferably 65% or more and 85% or
less. The above materials and manufacturing conditions are optimized, and the density of the
ceramic porous body 11 of the acoustic matching body 1 in the embodiment of the present
invention is adjusted by adjusting it at 200 kg / m <3> or more and less than 400 kg / m <3>. A
ceramic porous body 11 of low strength and high strength could be realized.
[0044]
Alternatively, for the porous ceramic body, a pore forming material is mixed with a material (for
example, alumina) forming the ceramic matrix, and the pore forming material is mixed with the
material forming the ceramic matrix and pressurized in a state of further firing treatment It may
be manufactured by the method of going, combining the said materials, and removing a pore
formation material. The pore-forming material is formed of a material that melts upon firing, or a
material that dissolves in a specific solvent, and is, for example, an acrylic sphere (melts upon
firing) or an iron sphere (dissolves in sulfuric acid). The material forming the ceramic matrix may
consist of the main material forming the framework and the auxiliary material which is different
in size from the main material and which hardens the main material. The auxiliary material is, for
example, glass.
[0045]
Here, since the acoustic matching body 10 has a structure in which a water-repellent film is
formed by vapor deposition so as to have a predetermined thickness on the surface forming the
skeleton of the ceramic porous body, a ceramic porous body that is easily hygroscopic in nature
The surface of the acoustic matching material is covered with the resin film and is not exposed,
and the moisture absorption of the acoustic matching member is suppressed even if it is left
under temperature change or high temperature and high humidity, and good output sensitivity
can be maintained. In addition, since the surface of the hard and brittle ceramic porous body is
covered with a flexible resin film to cover the brittleness, there is no concern that a part of the
ceramic porous body may be chipped or dusted.
14-04-2019
14
[0046]
Furthermore, even if a crack occurs in the ceramic porous body for some reason, if it is a small
gap, water is repelled by the water-repellent resin film, so it does not invade and the reliability is
further improved. This water-repellent film is formed by vapor deposition, and a resin material is
used so that the vaporized state becomes a monomer and becomes a polymer when attached to
the ceramic porous body in a medium vacuum atmosphere, so the vaporized resin material is a
monomer and particles Since it forms a strong polymer and forms a film when it adheres to a
small, narrow gap, it forms a pore with a pore diameter of 1 μm or less of the ceramic porous
body and forms a skeleton on the surface, It can be formed to have a predetermined thickness. In
addition, since the deposition process is performed in a medium vacuum atmosphere, the
thickness can be precisely controlled, and by applying a thin film without pinholes, the acoustic
characteristics of the ultrasonic transducer can be affected as much as possible. Therefore, film
variation due to the deposition process can be reduced.
[0047]
And, in a state where the acoustic matching body is disposed in close contact with the outside of
the case with the covering portion by the adhesion means, the vapor deposition process is
performed so as to obtain a predetermined thickness. A membrane is formed, and the acoustic
matching body is integrated with the outer side of the top portion of the case by means of a close
contact means, and is more firmly joined, and peeling of the acoustic matching body can be
prevented. And, at least in a state where the terminal board and the case are joined, the
deposition process is performed so as to obtain a predetermined thickness, so that a thin film
without pinholes is formed in the thin film by the evaporation process at the junction part of the
terminal board and the case. It is possible to protect the electric corrosion of the metal which is
likely to occur in the water pooling portion where the terminal plate and the case are formed as a
step in the joint portion, and to prevent the occurrence of rust and the like.
[0048]
In the acoustic matching body 10, a film-like acoustic film is formed on the surface opposite to
the contact surface on the outer side of the top of the case, so that the porosity near the surface
facing the fluid to be measured is a ceramic porous body. The vibration of the acoustic matching
body vibrated by the vibrator causes the fluid to be measured to vibrate (transmit), and vice
versa, because it is lower than the porosity near the surface of the formed acoustic matching
body and closer to a plane. It is possible to efficiently perform (receive) the acoustic matching
14-04-2019
15
body to be vibrated by the vibration of the fluid to be measured.
[0049]
In addition, since the acoustic film is formed by printing a resin material based on a
thermoplastic resin such as epoxy resin on a release film, and then transferring it to the surface
of the ceramic porous body, the ceramic has irregularities and is easy to suck in Since a
predetermined amount of resin material can be applied to the surface of the porous body, and
the thickness of the acoustic film can be made to a predetermined thickness, the acoustic
performance due to the change of the film thickness of the acoustic film can be stabilized.
[0050]
As described above, in the present embodiment, it is an acoustic matching body that includes a
piezoelectric body and is incorporated in an ultrasonic transducer that transmits or receives an
ultrasonic wave, and is water repellent to the skeleton formed of a porous body. An acoustic
matching body formed with a film having
[0051]
According to the above configuration, since the acoustic matching body has a water repellent
film formed on the porous skeleton, the porous skeleton that is easily hygroscopic in nature is
not exposed, and it is left under temperature change or high temperature and high humidity.
Even if it does, the moisture absorption of the acoustic matching body is suppressed, and a good
output can be maintained.
Further, since the porous body has a thin and fragile skeleton, forming a water-repellent resin
film having flexibility on the surface of the skeleton reduces the chipping and dusting properties
of the porous body.
[0052]
(Embodiment 2) The ultrasonic transducer 20 shown in FIG. 4 has a cylindrical case 21 with a
top, and is provided with a piezoelectric member 23 disposed in close contact with the inner wall
surface of the upper portion of the case by a bonding means 22. The acoustic matching body 26
formed of the ceramic porous body 25 disposed in close contact with the outer surface of the
hollowed portion of the case by the joining means 24 is adhered and fixed, and a film-like
acoustic film is formed on the opposite side. 27 is formed.
14-04-2019
16
[0053]
The hollow cylindrical case 21 and the terminal plate 28 are electrically joined by welding.
The terminal plate 28 includes electrode terminals 29 and 30, and these electrode terminals are
electrically insulated by the insulating member 31.
The electrode terminal 30, the conductive means 32, and the electrode 33 provided on the
piezoelectric body 23 are electrically joined, and the electrode terminal 29, the cylindrical case
21 having a cylindrical shape, and the electrode 34 provided on the piezoelectric body 23 are It
is joined electrically.
An electric signal is transmitted to the electrode provided on the piezoelectric body 23 through
the electrode terminals 29 and 30, and the piezoelectric body 23 converts the electric signal into
vibration, and the generated vibration is efficiently transmitted to the fluid to be measured. In
order to do so, the acoustic matching body 26 is provided.
[0054]
FIG. 5 shows a manufacturing process flow of the ultrasonic transducer 20 according to the
second embodiment of the present invention.
[0055]
FIG. 5 (a) adjusts the porous body 26 to a predetermined thickness and shape, and FIG. 5 (b)
applies a thermosetting adhesive used as the bonding means 22 to the piezoelectric body 23 and
forms a hollow cylinder The bonding means 24 is similarly applied and formed in the case 21.
In FIG. 6C, the piezoelectric body 23, the cylindrical case 21 having a hollow and the ceramic
porous body 25 are attached to each other, and the acoustic film 27 formed on the top portion of
the ceramic porous body 25 is screen-printed, metal mask printed, gravure The release sheet 35
is printed by a printing method such as printing, and is attached to the top of the ceramic porous
14-04-2019
17
body 25.
[0056]
The basic material used for the acoustic film 27 is, for example, thermosetting resin, epoxy resin,
phenol resin, polyester resin, melamine resin, and in some cases, these resins may be filled with
silica, ceramic powder, etc. Some particles such as are added. These particles reduce dripping
during printing and time-dependent changes in printing thickness. In this state, in the state
where the pressure of about 1 to 10 kg / cm <2> is applied to the piezoelectric body 23, the
hollow cylindrical case 21, and the porous ceramic body 25, the bonding means 22. In order to
cure the thermosetting adhesive used as and 24, heating is performed.
[0057]
FIG. 5 (d) illustrates the semi-finished product 36 thermally cured and joined by the abovedescribed steps, and the terminal having the cylindrical case 21 and the conductive means 32
inserted in the semi-finished product 36. The plate 28 is in a state of being electrically connected
by welding. At the time of this welding, argon gas which is inert gas, nitrogen gas, helium gas,
etc. is enclosed in the closed space 37, deterioration of the electrodes 33 and 34 of the
piezoelectric body 23, the joint portion between the piezoelectric body 23 and the hollow
cylindrical case Plays a role in reducing the deterioration of the
[0058]
The hollow cylindrical metal case 33 may be made of a material having conductivity, such as
iron, brass, copper, aluminum, stainless steel, an alloy thereof, or a metal obtained by plating the
surface of these metals.
[0059]
The thermosetting adhesive used as the bonding means is not particularly limited as long as it is
a thermosetting resin such as an epoxy resin, a phenol resin, a polyester resin, or a melamine
resin.
14-04-2019
18
In some cases, even if it is a thermoplastic resin, it can be used as an adhesive if the glass point
transfer is 70 ° C. or less, which is the high temperature use temperature.
[0060]
The method of manufacturing the ceramic porous body 25 is the same as that of the first
embodiment, and thus the description thereof is omitted. The method of forming the water
repellent film 13 formed on the skeleton 11 of the ceramic porous body 25 is the same as that of
the first embodiment, but in the second embodiment, as shown in FIG. The effect obtained differs
depending on which process is used to form 13. For example, as shown in (d) of FIG. 5, the
acoustic matching body is formed in the state of a semi-finished product 36 disposed in close
contact with the top outer wall surface of the hollow cylindrical case by close contact means. In
the state where the acoustic matching body is integrated with the outer side of the top of the
case by the adhesion means, the acoustic matching body is joined more firmly, and peeling of the
acoustic matching body can be prevented.
[0061]
Further, when the water repellent film 13 is formed at least in the state of the ultrasonic
transducer 20 in which the terminal board and the case are joined, not only the hygroscopicity
and dusting property of the porous body are improved, but also the terminal board Can protect
the metal's electric corrosion which is likely to occur in the water pool where the case and the
case are at the level difference of the joint, etc. Also, even if the terminal plate is plated to an
inexpensive metal such as iron for corrosion protection. Since the water repellent film 13 is also
formed on the portion of the terminal plate 28 which contacts the external environment, the
occurrence of rust and the like can be prevented.
[0062]
Alternatively, as shown in FIG. 6, the ceramic porous body shown in the first embodiment is
formed in a rod-like shape by the same manufacturing method, and a process flow is shown
when a water repellent film 13 is formed thereon. .
(A) of FIG. 6 shows a state in which the ceramic porous body is formed into a cylindrical rod
shape, and (b) of FIG. 6 shows that the rod-shaped ceramic porous body is water repellent
directly by vapor deposition treatment. The state which formed the film is shown.
14-04-2019
19
[0063]
Thereafter, in (c) of FIG. 6, the ceramic porous body is processed into a predetermined shape, and
an ultrasonic transducer can be obtained in the same manner as the manufacturing method
shown in FIG. As described above, by forming a rod-shaped ceramic porous body and a waterrepellent film, the acoustic matching body is vapor-deposited so as to have a predetermined
thickness on the surface of the rod-shaped ceramic porous body. After the resin film having
water repellency is applied, it is sliced into a predetermined shape, so that the strength of the
ceramic porous body is greatly increased by performing the vapor deposition treatment in a rod
state having a relatively strong strength. By slicing into shapes and using them, damage during
slicing and assembly can be prevented, and in the finished product state, part of the acoustic
matching body formed of the ceramic porous body is prevented from chipping and dusting It
becomes easy and can handle it at the time of an assembly etc.
[0064]
As described above, in the present embodiment, it is an acoustic matching body that includes a
piezoelectric body and is incorporated in an ultrasonic transducer that transmits or receives an
ultrasonic wave, and is water repellent to the skeleton formed of a porous body. An acoustic
matching body formed with a film having
[0065]
According to the above configuration, since the acoustic matching body has a water repellent
film formed on the porous skeleton, the porous skeleton that is easily hygroscopic in nature is
not exposed, and it is left under temperature change or high temperature and high humidity.
Even if it does, the moisture absorption of the acoustic matching body is suppressed, and a good
output can be maintained.
[0066]
Further, since the porous body has a thin and fragile skeleton, forming a water-repellent resin
film having flexibility on the surface of the skeleton reduces the chipping and dusting properties
of the porous body.
[0067]
Third Embodiment FIG. 7 is a cross-sectional view of an ultrasonic flow velocity / flow meter
14-04-2019
20
according to a third embodiment of the present invention.
[0068]
In FIG. 7, as shown in the ultrasonic transducers 41 and 42, the ultrasonic transducer 1 or 20
according to any of the first and second embodiments is shown in the flow rate measuring unit
40 in which the fluid flows. It has a configuration in which the pair is arranged diagonally.
L1 indicates the propagation path of the ultrasonic wave propagating from the ultrasonic
transducer 41 disposed on the upstream side, and L2 indicates the ultrasonic transducer
transmitted / received on the downstream side. The propagation path of the ultrasonic wave of
the vessel 42 is shown.
[0069]
Let V be the flow velocity of the fluid flowing through the tube, C be the velocity of the ultrasonic
waves in the fluid (not shown), and θ be the angle between the fluid flow direction and the
ultrasonic pulse propagation direction.
When the ultrasonic transducer 41 was used as an ultrasonic transducer, and the ultrasonic
transducer 42 was used as an ultrasonic transducer, the ultrasonic transducer 41 came out of the
ultrasonic transducer 41 The propagation time t1 for the ultrasonic pulse to reach the ultrasonic
transducer 42 is indicated by the following equation: t1 = L / (C + V cos θ) (2)
[0070]
Next, the propagation time t2 for the ultrasonic pulse emitted from the ultrasonic transducer 42
to reach the ultrasonic transducer 41 is t2 = L / (C−V cos θ) (3) It is indicated by).
Then, if the sound velocity C of the fluid is eliminated from the equations (2) and (3), the
equation V = L / 2 cos θ (1 / t1-1 / t2) (4) is obtained.
14-04-2019
21
[0071]
If L and θ are known, the flow velocity V can be obtained by measuring t1 and t2 with the timer
43.
If necessary, the flow rate Q can be obtained by multiplying the cross-sectional area S of the flow
rate measuring unit 40 and the correction coefficient K by the flow velocity V. The calculating
means 44 calculates the above Q = KSV. As described above, in the present embodiment, the
ultrasonic transducer provided with the acoustic matching body in which the water repellent film
13 is formed on the porous skeleton 11 and the ultrasonic wave propagation time between the
ultrasonic transducers are measured. By using an ultrasonic flow velocity flow meter including a
timing device, it is possible to provide an ultrasonic flow velocity flow meter that improves
reliability with high reliability against temperature changes or high temperature and high
humidity.
[0072]
The configuration of each of the other parts may be any configuration as long as the object of the
present invention is achieved.
[0073]
As described above, the ultrasonic transducer according to the present invention or the
ultrasonic velocity flowmeter using the same is deposited to a predetermined thickness on a
conventional acoustic matching body formed of a fragile and fragile porous body. By applying a
resin film having water repellency by treatment, mechanical strength is improved, and
condensation of the acoustic matching member due to temperature change or under high
temperature and high humidity is suppressed, and a decrease in output sensitivity due to
condensation is suppressed. It can be applied to applications such as automobile back sonar
exposed to the open air.
[0074]
Sectional view of the ultrasonic transducer according to the first embodiment of the present
invention. An enlarged sectional view of an essential part of the acoustic matching body formed
of the porous body according to the first embodiment of the present invention. Ceramic porous
material according to the second embodiment of the present invention. Production flow diagram
of the acoustic matching body formed of a body Cross-sectional view of the ultrasonic transducer
14-04-2019
22
in the second embodiment of the present invention Manufacturing process flow chart of the
ultrasonic transducer in the second embodiment of the present invention Implementation of the
present invention Process flow diagram of the ceramic porous body used for the acoustic
matching body in mode 2 Principle explanatory view of the ultrasonic flow velocity flowmeter
according to the third embodiment of the present invention A partial cross section of an acoustic
matching member to be incorporated into a conventional ultrasonic transducer Enlarged view
Explanation of sign
[0075]
Reference Signs List 1 ultrasonic transducer 3 piezoelectric body 10 acoustic matching body 13
water repellent film 14 acoustic film
14-04-2019
23
Документ
Категория
Без категории
Просмотров
0
Размер файла
39 Кб
Теги
description, jp2008263419
1/--страниц
Пожаловаться на содержимое документа