JP2008167147A - Ultrasonic wave transmitter-receiver and ultrasonic wave flow meter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ultrasonic wave transmitter-receiver and an ultrasonic wave flow meter having little dispersion in characteristics and small characterization by reliability test. <P>SOLUTION: The ultrasonic wave transmitter-receiver is formed by infiltrating a joining member into a porous sound matching layer subjected to hydrophobing processing and joining the vibrating means and the sound matching layer to thereby bring the porous sound matching layer subjected to hydrophobing processing into contact with the joining member in a wider area, surely joining the sound matching layer and the joining member. Vibrations of the vibrating means are efficiently transmitted to the sound matching layer to provide an ultrasonic wave transmitter-receiver having little dispersion in characteristics and little deterioration in characteristics even by a reliability test. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an ultrasonic transducer for use in a flow rate measuring device that measures the flow rate of gas using ultrasonic waves and a distance measuring device that measures the distance to an object, and in particular, the acoustic impedance of a piezoelectric vibrator and The present invention relates to an acoustic matching layer that matches the acoustic impedance of a fluid to be measured, and further relates to an ultrasonic transducer and an ultrasonic flowmeter using the acoustic matching layer.

  In recent years, an ultrasonic flowmeter that measures the time during which an ultrasonic wave propagates through a flow rate measurement unit, measures the moving speed of a fluid, and measures the flow rate is being used for a gas meter or the like. In such an ultrasonic flowmeter, accuracy is required, and in order to improve the accuracy, in an ultrasonic transducer that transmits ultrasonic waves to a gas or receives ultrasonic waves that have propagated through the gas, The acoustic impedance of the configured acoustic matching layer is important.

  The acoustic impedance Z is defined by the sound velocity C and the density ρ in the substance as shown in Expression (4).

Z = ρ × C (4)
The acoustic impedance differs greatly between a piezoelectric vibrator as a vibration means and a gas as an ultrasonic radiation medium. For example, the acoustic impedance (Z0) of a piezoelectric ceramic such as PZT (lead zirconate titanate), which is a general piezoelectric vibrator, is about 30 × 10 ⁶ kg / m ² / s. Further, the acoustic impedance (Z3) of a gas that is a radiation medium, for example, air, is about 400 kg / m ² / s. On such boundary surfaces having different acoustic impedances, the propagation of the sound wave is reflected, and the intensity of the transmitted sound wave becomes weak. As a method for solving this problem, the acoustic impedances Z0 and Z3 of the piezoelectric vibrator as the vibration means and the gas as the ultrasonic radiation medium have an acoustic impedance having a relationship of the formula (5) between the two. In general, a method of increasing the intensity of sound wave transmission by reducing the reflection of sound by inserting a substance having the above is known.

Z = (Z0 × Z3) ^(1/2) (5)
The optimum value when the acoustic impedance satisfying this condition is matched is about 11 × 10 ⁴ kg / m ² / s. An acoustic matching layer that satisfies this acoustic impedance is required to be solid, low in density, and low in sound speed, and not to be destroyed even when an ultrasonic transducer is used.

Conventionally, in this type of ultrasonic transducer, a porous body having a void that can reduce the density of the acoustic matching layer may be used. This type of ultrasonic transmission / reception is often used in air or in gas, and depending on the usage, it may be used under high humidity conditions. In such a situation, the void portion of the acoustic matching layer made of a porous body may absorb moisture. The acoustic impedance of water is 1.41 × 10 ⁶ kg / m ² / s, which is larger than that of an acoustic matching layer made of a porous material. When the acoustic matching layer absorbs moisture, the density of the acoustic matching layer is apparently increased. , The speed of sound increases and the acoustic impedance increases. As a result, there is a problem that the intensity of sound waves transmitted into the air or gas is weakened. On the other hand, the acoustic matching layer has been hydrophobized so that the solid skeleton of the acoustic matching layer made of a porous material does not absorb moisture, and such a problem has been solved (see, for example, Patent Document 1).
JP 2002-262394 A

  However, in the conventional configuration, when the acoustic matching layer subjected to the hydrophobization treatment is joined with an adhesive, the adhesion between the acoustic matching layer and the adhesive is poor, and the variation in characteristics increases. Or a characteristic may deteriorate greatly by a reliability test.

  SUMMARY OF THE INVENTION The present invention solves the above-described conventional problems, and an object thereof is to provide an ultrasonic transmitter / receiver that has a small variation in characteristics and that has small characteristics even in a reliability test.

  In order to solve the above-described conventional problems, the ultrasonic transducer of the present invention is formed by infiltrating a bonding member into a porous acoustic matching layer subjected to a hydrophobization treatment and bonding the vibration means and the acoustic matching layer. This is an ultrasonic transducer.

  As a result, the hydrophobic acoustically treated porous acoustic matching layer and the joining member are in contact with each other in a larger area, reliably joined, and vibration of the vibration means is efficiently transmitted to the acoustic matching layer, and the characteristic variation is small. Even in the reliability test, an ultrasonic transducer with little deterioration in characteristics is obtained.

  The ultrasonic transducer according to the present invention can be an ultrasonic transducer with small variation in characteristics and small degradation of characteristics even in a reliability test.

  According to a first aspect of the present invention, there is provided an ultrasonic wave transmitter / receiver in which a bonding member is infiltrated into a hydrophobic porous acoustic matching layer and the vibration means and the acoustic matching layer are bonded to each other. Since it penetrates and solidifies in the complex voids of the quality acoustic matching layer, the acoustic matching layer and the vibration means are reliably joined, the vibration of the vibration means is efficiently transmitted to the acoustic matching layer, and the characteristic variation is small, reliability. It becomes an ultrasonic transducer with little deterioration of characteristics even by the test.

  According to a second aspect of the present invention, in the porous body formed of one structure, the other structure is formed in part or all of the voids of the porous body, and the other structure is smaller than the one structure. By forming a porous body having voids, one structure and the other structure are ultrasonic transducers in which a bonding member is infiltrated into a hydrophobized acoustic matching layer and the vibration means and the acoustic matching layer are bonded. Since the bonding member permeates and solidifies into one of the hydrophobic structures and the complex voids of the other structure, the acoustic matching layer and the vibration means are securely bonded, and the vibration of the vibration means is Therefore, the ultrasonic transducer is small in characteristic variation and small in characteristic deterioration even in reliability tests.

  According to a third aspect of the present invention, the vibration means is disposed on an inner surface of the sealed container, and the acoustic matching layer is disposed on an outer surface facing the piezoelectric vibrator through the sealed container. By using this ultrasonic transducer, since the vibrating means does not come into contact with the atmosphere, it can operate stably even under high temperature and high humidity, and can maintain stable characteristics over a long period of time.

  According to a fourth aspect of the present invention, there is provided the ultrasonic transducer according to claim 1 or 2, wherein the joining member is a member whose viscosity is temporarily lowered by heating and hardens. It can join easily by heating the joining member formed in this.

  According to a fifth aspect of the invention, in the ultrasonic transducer according to claim 2, the joining member is made of a member containing particles smaller than the voids of the other structure, whereby the viscosity of the joining member can be easily adjusted. The ultrasonic transducer can be formed and penetrated with a stable thickness, the vibration of the vibration means is reliably transmitted to the acoustic matching layer, the characteristic variation is small, and the characteristic deterioration is small even by a reliability test.

  According to a sixth aspect of the present invention, when one of the structures is made of a ceramic, the ultrasonic transducer according to claim 2, wherein the ceramic is an inorganic substance, so that the characteristic change is small and stable even in a wide temperature range. Since the acoustic matching layer can be made lightweight, the acoustic matching layer can be made low in acoustic impedance, and the intensity of the ultrasonic wave transmitted into the air or gas can be increased. .

  According to a seventh aspect of the present invention, the ultrasonic wave transmitter / receiver according to claim 2, wherein the other structural body is made of organic glass, and since it is an inorganic substance, its characteristic change is small even in a wide temperature range and stable ultrasonic waves are obtained. Since it can be a transducer, and the acoustic matching layer can be made lightweight, it becomes an acoustic matching layer with low acoustic impedance, and the intensity of the ultrasonic wave that penetrates into air or gas can be made stronger. Since it can be formed by the sol-gel method, a raw material that is liquid can be infiltrated into the void of one structure and can be made solid by reaction, so that the other structure can be easily formed in the void of one structure. be able to.

  According to an eighth aspect of the present invention, there is provided a ceramic, a step of introducing bubbles into a ceramic slurry having a hardly fired ceramic powder, a step of gelling the ceramic slurry, a step of drying the gelled ceramic slurry, and the gelation A high porosity can be realized by using the ultrasonic transducer according to claim 6 formed by the step of degreasing the ceramic slurry and the step of firing the gelled ceramic slurry. The matching layer can be reduced in weight, can be an acoustic matching layer with low acoustic impedance, and can increase the intensity of sound waves transmitted into air or gas.

  According to a ninth aspect of the invention, the organic glass contains a gel obtained by polymerizing and drying a compound represented by the formula (1) or a partially hydrolyzed polymer of the compound represented by the formula (1). 7 makes it possible to react in a shorter time than other organosilane compounds, and density adjustment is easy.

  According to a tenth aspect of the present invention, the organic glass is hydrolyzable in the presence of a wet gel obtained by polymerizing a compound represented by the formula (1) or a partially hydrolyzed polymer of the compound represented by the formula (1). The transmitter / receiver according to claim 7, wherein an organic silane compound in which an organic group and a non-hydrolyzable organic group are directly bonded to the same silicon is polymerized and dried, thereby combining strength and flexibility. Organic matching glass is obtained, and the acoustic matching member using this is effective in preventing its own damage because the silica dry gel follows the expansion and contraction even if the bonded member expands and contracts due to temperature changes in the usage environment. Therefore, the ultrasonic transducer can operate stably in a wide temperature range.

  In an eleventh aspect of the invention, the organosilane compound is obtained by polymerizing an organosilane compound in which the hydrolyzable organic group represented by the formulas (2) and (3) and the non-hydrolyzable organic group are directly bonded to the same silicon. An organic glass having both strength and flexibility can be obtained by using the ultrasonic wave transmitter / receiver according to claim 10, wherein the acoustic matching member is used to change the temperature of the usage environment. Even if the bonded member expands and contracts, the silica dry gel follows the expansion and contraction, so that it has the effect of preventing its own damage, and the ultrasonic transducer can operate stably in a wide temperature range. .

In a twelfth aspect of the invention, the organosilane compound is a linear polysiloxane diol represented by the formula (4). The ultrasonic transducer according to claim 10 has both strength and flexibility. The organic matching glass using this has an effect of preventing its own damage because the silica dry gel follows the expansion and contraction even when the bonded member expands and contracts due to the temperature change of the use environment. In addition, the ultrasonic transducer can operate stably over a wide temperature range.

  In a thirteenth aspect of the invention, the organosilane compound includes a copolymer of at least one of the formula (5), the formula (6), and the compound represented by the formula (7). By using an ultrasonic transducer, an organic glass with both strength and flexibility can be obtained, and the acoustic matching member using this is silica-dried even if the member to be joined expands or contracts due to temperature changes in the usage environment. Since the gel follows the expansion and contraction, it has an effect of preventing its own breakage, and the ultrasonic transducer can operate stably in a wide temperature range.

  A fourteenth aspect of the present invention is an ultrasonic flowmeter comprising the ultrasonic transducer according to any one of claims 1 to 13, wherein the flow rate measuring unit through which the fluid to be measured flows and the flow rate measuring unit include the A pair of the ultrasonic transducers arranged opposite to the upstream side and the downstream side of the flow of the fluid to be measured, an ultrasonic propagation time measuring circuit between the pair of ultrasonic transducers, and the propagation time Based on the above, it is possible to realize a highly reliable flow meter by using an ultrasonic flow meter including a calculation means for calculating the flow rate of the fluid to be measured.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, this invention is not limited by the form of this invention.

(Embodiment 1)
FIG. 1 is a sectional view of an ultrasonic transducer according to the first embodiment of the present invention.

  In FIG. 1, an ultrasonic transducer 1 is composed of an acoustic matching layer 2, a vibrating means 3 and a joining member 4.

  The porous acoustic matching layer 2 and the piezoelectric body that is the vibration means 3 including the opposing electrode 5 and electrode 6 have a structure joined by the joining means 4. The piezoelectric electrode 5 and the electrode 6 which are the vibration means 3 are electrically joined to the lead wire 7 and the lead wire 8, and the electrode and the lead wire are connected by, for example, welding or conductive paste.

  The acoustic matching layer 2 is a porous structure having a plurality of spaces and a skeleton for forming the spaces. The material is not particularly limited as long as it is a material having continuous voids such as ceramic porous body, porous organic glass, foamed polyimide, and foamed polyethylene, and low acoustic impedance can be realized because the density can be further reduced. Can do. The bonding member 4 is, for example, an epoxy resin as a main agent, fine particles such as silica and alumina added for viscosity adjustment, an adhesive added with a curing agent, or an organic material such as a sheet adhesive at room temperature. Is applicable. Further, it can be used as a joining member such as a conductive paste obtained by mixing inorganic conductive particles such as silver paste together with a thermosetting resin, or a brazing material such as silver brazing. In the manufacturing method of the ultrasonic transducer 1, first, the acoustic matching layer 2 is adjusted to a thickness of ¼ wavelength, and a bonding member is attached to at least one electrode surface of the piezoelectric body that is the acoustic matching layer 2 or the vibration means 3. 4 is applied and formed, one electrode 5 of the vibration means 3 and the acoustic matching layer 2 are bonded to each other, pressure-fixed with a jig or the like, and put together with the jig in an oven, and the bonding member 4 is cured and bonded. . For the bonding member 4, a material that was temporarily reduced in viscosity by heating and penetrated into the acoustic matching layer 2 and further cured by being heated was selected.

  The operation and action of the ultrasonic transducer 1 configured as described above will be described below. First, by applying a pulse voltage having a frequency of about 200 to 600 KHz to the lead wire 7 and the lead wire 8 from the outside, the piezoelectric body as the vibration means 3 vibrates in the direction perpendicular to the electrode surface and resonates with the vibration. The acoustic matching layer 2 adjusted to the thickness (1/4 wavelength) vibrates, and the vibration is efficiently transmitted from the acoustic matching layer 2 into the air or gas.

  As described above, in the present embodiment, the bonding member 4 penetrates into the voids of the hydrophobized acoustic matching layer 2, so that the vibration means 3 and the acoustic matching layer 2 are reliably connected and efficiently. Therefore, it is an ultrasonic wave transmitter / receiver in which the characteristic variation is small and the characteristic deterioration is small even by the reliability test.

(Embodiment 2)
FIG. 2 shows a cross-sectional view of the ultrasonic transducer 10 in the second embodiment of the present invention, and FIG. 3 shows an enlarged cross-sectional view of the acoustic matching layer 10 in the second embodiment of the present invention. It is.

  2 and 3, the ultrasonic transducer 10 includes an acoustic matching layer 11, a vibration unit 12, and a joining member 14.

  The porous acoustic matching layer 11 and the piezoelectric body that is the vibration means 12 including the electrode 15 and the electrode 16 facing each other have a structure joined by the joining means 14. The piezoelectric electrode 15 and the electrode 16 which are the vibration means 12 are electrically joined to the lead wire 17 and the lead wire 18, and the electrode and the lead wire are connected by, for example, welding or conductive paste.

  The acoustic matching layer 11 is a porous body formed by one structure 19 having a plurality of spaces and a skeleton for forming the space, and the other structure having a void smaller than the one structure 19 in the void. This is a composite porous body formed on the body 20. For example, the material of the one structure 19 is preferably a ceramic material, and is not particularly limited as long as it is a material having continuous voids. Since the density can be reduced by using such a porous body, a low acoustic impedance can be realized. For example, porous organic glass is used for the other structure 20. Hereinafter, the manufacturing method of one structure 19 and the other structure is shown below.

  The manufacturing method of one structure 19 is preferably formed as follows. FIG. 4 shows a manufacturing process of one structure in the second embodiment of the present invention.

  One structure 19 is composed of at least oxide-based or non-oxide-based ceramics, clay mineral, or the like. Examples of oxide ceramics include alumina, mullite, and zirconia. Non-oxide ceramics include silicon carbide, silicon nitride, nitrided aluminum, boron nitride, and graphite. Can be mentioned. One structure 19 is preferably composed of a hardly fired ceramic, more preferably composed of a glass ceramic that is an oxide material selected from aluminum titanate, cordurite, and a lithia-alumina-silica compound. The If one of the structures 19 is made of glass ceramics, the coefficient of thermal expansion is small, so that when used as an acoustic matching member of the ultrasonic transmitter / receiver of the holder, sound waves can be transmitted / received stably over a wide temperature range. This is preferable.

  The manufacturing of one structure 19 includes a step of pulverizing these hardly sinterable ceramics, a step of adding an additive to the ceramic powder to form a slurry, and introducing bubbles, a step of casting the slurry into a mold, It consists of the process of baking. This will be described in detail below.

(Hard-sintering ceramic grinding process)
Ceramics can be pulverized by mixing, pulverizing, or the like using a ball mill or pot mill. The average particle size of the ceramic powder is not particularly limited, but is preferably 10 μm or less. This is because the use of ceramics having an average particle diameter in this range improves the powder dispersibility in the slurry and also improves the sinterability.

(Ceramic powder slurrying process)
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 an appropriate dispersant. As the dispersant, a polycarboxylic acid-based dispersant (anionic dispersant) can be used. Specifically, ammonium polycarboxylate or sodium polycarboxylate can be used. Preferably, a dispersant having a large change in slurry viscosity with the addition amount of the dispersant is used. The amount of the dispersant used is preferably 5% by weight or less, more preferably 1% by weight or less, based on the weight of the ceramic powder.

  The ceramic slurry is defoamed before introducing the ceramic slurry bubbles, and the bubbles are introduced while stirring the slurry. When air bubbles are introduced into the ceramic slurry, a gelling agent or a polymerizable material composed of a monomer and a polymerization initiator is added in order to form a desired shape. When a gelling agent is used, the slurry is gelled by temperature control or pH control. Examples of the gelling agent include gelatin, agarose, agar, sodium alginate and the like.

  When a polymerizable material is used, a monomer of the polymerizable material is used. Specific examples include monomers having one or more vinyl groups or allyl groups. 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 preparing water as a solvent in the slurry, preferably, at least one monofunctional (meth) acrylic amide and at least one bifunctional (meth) acrylic amide Are used in combination. When the slurry is prepared with an organic solvent, preferably, at least two types of bifunctional (meth) acrylic acid are used in combination.

  When a monofunctional monomer or a bifunctional monomer is used, ammonium persulfate, potassium persulfide, or the like is preferable. Moreover, when using the functional monomer which has a 2 or more functional group, Preferably, an organic peroxide, a hydrogen peroxide compound, an azo, or a diazo compound is used. Specifically, it is benzoyl peroxide.

  The introduced gas is preferably held in the slurry as bubbles by a surfactant or the like. The surfactant is preferably added to the ceramic slurry before introducing the bubbles by stirring or the like in the bubble introducing step. Examples of the surfactant include an anionic surfactant such as an alkylbenzene sulfonic acid, and a cationic surfactant such as a higher alkyl amino acid. Specifically, n-dodecylbenzenesulfonic acid, polyoxyethylene sorbitan monolaurate, polyoxyethylene monooleate, polyoxyethylene nonylphenyl ether, polyoxyethylene lauryl ether, and alkali metal salts thereof such as sodium and potassium are used. Can be mentioned. Further, triethanolamine lauryl ether and the like and halogenated salts thereof, sulfate, acetate, hydrochloride and the like can be mentioned. Moreover, diethyl hexyl succinic acid and its alkali metal salt etc. can be mentioned.

(Bubble introduction process)
Bubbles are introduced into the slurry prepared as described above. In the bubble introduction step, when a polymerizable material is used as the gelling material, 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 a gelation process can be adjusted with gelation temperature or its addition amount. Usually, when a polymerization catalyst is added, gelation (polymerization) starts rapidly 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. Examples of the polymerization catalyst include N, N, N ′, N′-tetramethylethylenediamine and the like.

(Slurry molding process)
The cell-containing ceramic slurry thus prepared is poured into a mold or the like to be gelled, thereby forming a gel-like porous molded body. The foamed ceramic slurry is poured into a cylindrical mold and solidified by polymerization reaction or gelation reaction. When the slurry is solidified, the air bubbles present in the slurry are also stored in the gel. As a result, the solidified body becomes porous, and a gel-like porous molded body is obtained. This is demolded, dried, degreased and fired. Drying is performed so as to evaporate 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 components (gelling agent or polymer) constituting the skeleton of the gel-like porous molded body. Usually, it is 20 ° C or higher, preferably 25 ° C or higher and 80 ° C or lower, more preferably 25 ° C or higher and 40 ° C or lower.

(Baking process)
Next, in order to remove organic components from the dried product, heating is performed at a higher 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, N-methylenebisacrylamide as a material for gelation, degreasing is performed at 700 ° C. for 2 days.

  After degreasing, a firing process is performed. The conditions for firing are set in consideration of the type of ceramic material used. By such a process, one structure 19 of the present invention can be obtained.

  The manufacturing method of the other structure 20 is preferably formed as follows. FIG. 5 shows a manufacturing process of the other structure according to the second embodiment of the present invention.

The other structure 20 is formed of organic glass and is formed by a sol-gel method.
The material of the organic glass contained in the acoustic matching layer 11 is not particularly limited. The method for producing organic glass will be described in detail. FIG. 5 shows a manufacturing process of another structure according to the second embodiment of the present invention. As shown in the figure, it is formed by four steps. This will be described in detail below.

(Step 1: First gelation step)
In this embodiment, first, a first wet gel is formed by a so-called sol-gel method. In that case, a 1st catalyst (gelation catalyst) is added to a 1st gel raw material, and gelatinization is advanced.

  As the gel material used in the manufacturing method of the present embodiment, a general material used in the sol-gel method is used. For example, there are oxide fine particles such as silicon, aluminum, zirconium and titanium, and corresponding alkoxides. Among these, a compound containing silicon as a metal is preferable from the viewpoint of availability. In the case of the metal alkoxide, as already described, silicon is preferable from the viewpoint of easy reaction control. For example, tetraalkoxysilanes such as tetramethoxysilane and tetraethoxysilane, and silicon alkoxides such as trialkoxysilane and dialkoxysilane are used.

(Example)
Examples of the silicon compound in which the hydrolyzable organic group and the non-hydrolyzable organic group are directly bonded to the same silicon for realizing the present invention are as follows.

  Organosiloxane comprising a hydrolyzed polymer of a compound represented by formula (1) or formula (2) and having a molecular weight of 200 or more. A linear polysiloxane diol in which the silicon compound is represented by the formula (3).

The R ^1, is not particularly limited, for example, is used which the alkyl group of 1 to 4 carbon atoms as a main raw material.

The R ^2, is not particularly limited, and examples thereof include monovalent hydrocarbon groups of the substituted or unsubstituted 1-8 carbon atoms. Specifically, alkyl groups such as methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group and octyl group; cycloalkyl groups such as cyclopentyl group and cyclohexyl group; 2-phenylethyl group, Aralkyl groups such as 3-phenylpropyl group; aryl groups such as phenyl group and tolyl group; alkenyl groups such as vinyl group and allyl group; chloromethyl group, γ-chloropropyl group, 3,3,3-trifluoropropyl A halogen-substituted hydrocarbon group such as a group; substituted hydrocarbon groups such as γ-methacryloxypropyl group, γ-glycidoxypropyl group, 3,4-epoxycyclohexylethyl group, γ-mercaptopropyl group, etc. Can do. Among these, an alkyl group having 1 to 4 carbon atoms and a phenyl group are preferable from the viewpoint that synthesis is easy, availability, and hardness does not decrease excessively.

  Accordingly, the organotrialkoxysilane of formula (1) includes methyltrimethoxysilane, methyltriethoxysilane, methyltriisopropoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, 3,3,3-trifluoropropyltrimethyl. A methoxysilane etc. can be illustrated.

  Examples of the diorganodialkoxysilane of formula (2) include dimethyldimethoxysilane, dimethyldiethoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane, and methylphenyldimethoxysilane.

  These silicon compounds may contain a compound represented by the formula (4, 5, 6).

R ⁴ in the formula (4) is a substituted or unsubstituted hydrocarbon group having 1 to 9 carbon atoms.

R ⁵ in the formula (5) is at least one selected from the group consisting of an epoxy group, a glycidyl group, and a hydrocarbon group containing at least one of them (for example, γ-glycidoxypropyl group, etc.). At least one of the groups.

R ⁶ in formula (6) is a hydrocarbon group containing an alkoxysilyl group and / or a halogenated silyl group, such as a trimethoxysilylpropyl group, a dimethoxymethylsilylpropyl group, a monomethoxydimethylsilylpropyl group, a triethoxysilylpropyl group. Group, diethoxymethylsilylpropyl group, ethoxydimethylsilylpropyl group, trichlorosilylpropyl group, dichloromethylsilylpropyl group, chlorodimethylsilylpropyl group, chlorodimethoxysilylpropyl group, dichloromethoxysilylpropyl group, etc. One type.

  Moreover, the silicon compound according to the present invention may contain a silicon compound represented by the formula (7). Examples of the tetraalkoxysilane represented by the formula (7) include tetramethoxysilane and tetraethoxysilane.

(effect)
Any of the compounds or polymers or copolymers represented by the formulas (1) to (6) is a component that softens the dried gel and makes it difficult to cause cracking or peeling. By polymerizing the compound represented by the formula (1,2) so as to have a molecular weight of 200 or more, the effect of softening the gel obtained is increased. For example, even when a compound represented by the formula (1,2) is used, if a monomer having a low molecular weight is used, the dried gel cannot be softened and a sufficient effect cannot be obtained. . The compound represented by the formula (3) also has a great softening effect, and particularly when used simultaneously with the tetraalkoxysilane represented by the formula (7), it is easy to copolymerize (crosslink) with this, so that the reaction rate is low. Easy to control. The compounds represented by the formulas (4, 5, 6) also have a great effect on softening the gel. Although it may be represented by a relatively simple chemical formula as represented by the formula (4), in particular, when a compound represented by the formula (5) is used, the adhesion to the bonded layer is improved, and When the compound represented by the formula (6) is used, when used together with the tetraalkoxysilane represented by the formula (7), it is easy to copolymerize (crosslink) with this, so that a greater softening effect can be obtained. It is done.

(concentration)
The concentration contained in the dry gel of the compound or polymer or copolymer represented by the formulas (1) to (6) is not particularly specified, but is preferably 0.01% to 100. If the concentration of this component is too low, cracking and peeling of the dried gel cannot be prevented. On the other hand, if it is too high, the strength decreases and shrinkage occurs when the wet gel is dried. For these reasons, the concentration of this compound is more preferably 0.1 to 10%.

  As the gelation catalyst, a general organic acid, inorganic acid, organic base, or inorganic base is used. Examples of organic acids include acetic acid and citric acid, inorganic acids such as sulfuric acid, hydrochloric acid, and nitric acid, organic bases such as piperidine, and inorganic bases such as ammonia. In addition, use of an imine type such as piperidine is more preferable from the viewpoint of reducing capillary force because of the effect of increasing the pore diameter. Solvents include lower alcohols such as methanol, ethanol, propanol, butanol, ethylene glycol and diethylene glycol, mono- or diethers of ethylene glycol and diethylene glycol, lower ketones such as acetone, lower ethers such as tetrahydrofuran and 1,3-dioxolane. A water-soluble organic solvent is used. Moreover, when a gel is formed by hydrolysis and condensation polymerization of the first gel raw material, water necessary for hydrolysis is also added (step 2: restructuring step).

  Subsequent to the first gelation step, a reconstruction step is performed.

  In addition, when a wet gel is formed at the time of a 1st gelatinization process, it arrange | positions so that a 1st wet gel may touch a reconstruction raw material solution, and a reconstruction process is performed.

  In the reconstruction process, a new solid skeleton (second solid skeleton) is formed while decomposing a part of the solid skeleton of the first wet gel formed in the first gelation process. Specifically, first, a restructuring raw material solution is prepared by adding and mixing a restructuring raw material for the restructuring step, a restructuring catalyst and water, and, if necessary, a solvent. The first wet gel obtained in (1) is immersed.

  Addition of the restructuring catalyst promotes polymerization and accelerates the growth of a new solid skeleton. Moreover, the addition of water and a restructuring catalyst acts to break down the fine pore structure of the first wet gel by advancing decomposition (dissolution) of the fine particles constituting the solid skeleton of the first wet gel by hydrolysis. Furthermore, this hydrolysis is also accelerated by the restructuring catalyst described above. As described above, since the speed of breaking the old solid skeleton (first solid skeleton) and the speed of forming the new solid skeleton (second solid skeleton) are both very high, the solid with a significant change in pore structure. The skeleton can be reconstructed.

As the reconstruction catalyst used in the reconstruction process, those in the group of gelation catalysts used in the first gelation process can be used, and in particular, the same as the gelation catalyst in the first gelation process. Need not be.

  Further, as the reconstructed gel raw material used in the restructuring step, the gel raw material used in the first gelation step is used, and the relationship between the first gel raw material and the reconstructed gel raw material is not particularly limited. For example, when tetraethoxysilane, which is an alkoxysilane, is used as the gel material in the first gelation step, tetraethoxysilane can be used as the reconstructed gel material in the reconstruction step, If a solvent to be dissolved is selected, other metal alkoxides and aqueous silicic acid solutions can also be used.

  The solvent used in this step is not particularly limited as long as the reconstructed gel raw material and the reconstructed catalyst are dissolved as described above.

(Example)
Examples of the silicon compound in which the hydrolyzable organic group and the non-hydrolyzable organic group are directly bonded to the same silicon for realizing the present invention are as follows.

  Organosiloxane comprising a hydrolyzed polymer of a compound represented by formula (1) or formula (2) and having a molecular weight of 200 or more. A linear polysiloxane diol in which the silicon compound is represented by the formula (3).

The R ^1, is not particularly limited, for example, is used which the alkyl group of 1 to 4 carbon atoms as a main raw material.

The R ^2, is not particularly limited, and examples thereof include monovalent hydrocarbon groups of the substituted or unsubstituted 1-8 carbon atoms. Specifically, alkyl groups such as methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group and octyl group; cycloalkyl groups such as cyclopentyl group and cyclohexyl group; 2-phenylethyl group, Aralkyl groups such as 3-phenylpropyl group; aryl groups such as phenyl group and tolyl group; alkenyl groups such as vinyl group and allyl group; chloromethyl group, γ-chloropropyl group, 3,3,3-trifluoropropyl A halogen-substituted hydrocarbon group such as a group; substituted hydrocarbon groups such as γ-methacryloxypropyl group, γ-glycidoxypropyl group, 3,4-epoxycyclohexylethyl group, γ-mercaptopropyl group, etc. Can do. Among these, an alkyl group having 1 to 4 carbon atoms and a phenyl group are preferable from the viewpoint that synthesis is easy, availability, and hardness does not decrease excessively.

  Accordingly, the organotrialkoxysilane of formula (1) includes methyltrimethoxysilane, methyltriethoxysilane, methyltriisopropoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, 3,3,3-trifluoropropyltrimethyl. A methoxysilane etc. can be illustrated.

  Examples of the diorganodialkoxysilane of formula (2) include dimethyldimethoxysilane, dimethyldiethoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane, and methylphenyldimethoxysilane.

  These silicon compounds may contain a compound represented by the formula (4, 5, 6).

R ⁴ in the formula (4) is a substituted or unsubstituted hydrocarbon group having 1 to 9 carbon atoms.

R ⁵ in the formula (5) is at least one selected from the group consisting of an epoxy group, a glycidyl group, and a hydrocarbon group containing at least one of them (for example, γ-glycidoxypropyl group, etc.). At least one of the groups.

R ⁶ in formula (6) is a hydrocarbon group containing an alkoxysilyl group and / or a halogenated silyl group, such as a trimethoxysilylpropyl group, a dimethoxymethylsilylpropyl group, a monomethoxydimethylsilylpropyl group, a triethoxysilylpropyl group. Group, diethoxymethylsilylpropyl group, ethoxydimethylsilylpropyl group, trichlorosilylpropyl group, dichloromethylsilylpropyl group, chlorodimethylsilylpropyl group, chlorodimethoxysilylpropyl group, dichloromethoxysilylpropyl group, etc. One type.

  Moreover, the silicon compound according to the present invention may contain a silicon compound represented by the formula (7). Examples of the tetraalkoxysilane represented by the formula (7) include tetramethoxysilane and tetraethoxysilane.

(effect)
Any of the compounds or polymers or copolymers represented by the formulas (1) to (6) is a component that softens the dried gel and makes it difficult to cause cracking or peeling. By polymerizing the compound represented by the formula (1,2) so as to have a molecular weight of 200 or more, the effect of softening the gel obtained is increased. For example, even when a compound represented by the formula (1,2) is used, if a monomer having a low molecular weight is used, the dried gel cannot be softened and a sufficient effect cannot be obtained. . The compound represented by the formula (3) also has a great softening effect, and particularly when used simultaneously with the tetraalkoxysilane represented by the formula (7), it is easy to copolymerize (crosslink) with this, so that the reaction rate is low. Easy to control. The compounds represented by the formulas (4, 5, 6) also have a great effect on softening the gel. Although it may be represented by a relatively simple chemical formula as represented by the formula (4), in particular, when a compound represented by the formula (5) is used, the adhesion to the bonded layer is improved, and When the compound represented by the formula (6) is used, when used together with the tetraalkoxysilane represented by the formula (7), it is easy to copolymerize (crosslink) with this, so that a greater softening effect can be obtained. It is done.

(concentration)
The concentration contained in the dry gel of the compound or polymer or copolymer represented by the formulas (1) to (6) is not particularly specified, but is preferably 0.01% to 100. If the concentration of this component is too low, cracking and peeling of the dried gel cannot be prevented. On the other hand, if it is too high, the strength decreases and shrinkage occurs when the wet gel is dried. For these reasons, the concentration of this compound is more preferably 0.1 to 10%.

(Process 3: Hydrophobization process)
Following the reconstruction process, a hydrophobization process is performed. In this step, a hydrophobic group is introduced by reacting a hydrophobizing agent dissolved in a solvent with the surface of the wet gel obtained up to the restructuring step. In the case of chlorosilane or the like, which will be described later, the hydrophobizing agent reacts with water and decreases the reactivity with the wet gel surface. Therefore, the hydrophobizing agent can be washed with a water-soluble solvent before hydrophobization or with water. It is preferable to remove water by distilling off using a boiling solvent.

  The hydrophobizing agent used in the present invention is preferably a silylating agent from the viewpoint of high reactivity, and examples thereof include silazane compounds, chlorosilane compounds, alkylsilanol compounds and alkylalkoxysilane compounds.

In the case of a silazane compound, a chlorosilane compound, or an alkylalkoxysilane compound, these silylating agents react with silanol groups on the gel surface after being directly or hydrolyzed to the corresponding alkylsilanol. Further, when alkylsilanol is used as a silylating agent, it reacts with the silanol group on the surface as it is.

  Among these, chlorosilane compounds and silazane compounds are particularly preferred because of their high reactivity during hydrophobization and availability, and because they are easily available and do not generate gases such as hydrogen chloride and ammonia during hydrophobization. Alkyl alkoxysilanes are particularly preferably used.

  Specifically, chlorosilane compounds such as trimethylchlorosilane, methyltrichlorosilane and dimethyldichlorosilane, silazane compounds such as hexamethyldisilazane, methoxytrimethylsilane, ethoxytrimethylsilane, dimethoxydimethylsilane, dimethoxydiethylsilane and diethoxydimethylsilane There are silylating agents represented by silanol compounds such as alkylalkoxysilane compounds, trimethylsilanol and triethylsilanol. If these are used, hydrophobization can be promoted by introducing an alkylsilyl group such as a trimethylsilyl group into the wet gel surface.

  Further, if a fluorinated silylating agent is used as the hydrophobizing agent, the hydrophobicity becomes strong and is very effective.

  In addition, as hydrophobizing agents, alcohols such as ethanol, propanol, butanol, hexanol, heptanol, octanol, ethylene glycol and glycerol, carboxylic acids such as formic acid, acetic acid, propionic acid and succinic acid can also be used. . These are hydrophobized by reacting with the hydroxyl groups on the gel surface to form ethers or esters, but the reaction is relatively slow and requires high-temperature conditions (step 4: drying step).

  Following the hydrophobization step, a drying step is performed. In this step, a dry gel is obtained by removing the solvent from the wet gel obtained up to the hydrophobization step.

  There are three drying methods for removing the solvent from the wet gel: (1) heat drying method (2) supercritical drying method (3) freeze drying method. The heating and drying method is the most common and simple drying method, in which the wet gel containing the solvent is heated to vaporize and remove the solvent in the liquid state. Most preferred. In addition, "heat drying" here includes natural drying in which the above-described degree of heating is extremely low and left to dry without heating. When drying, if the gel density is low, the gel may temporarily shrink and crack due to capillary forces proportional to the surface tension of the solvent in the gel. For this reason, the solvent for drying is preferably a hydrocarbon-based solvent having a low surface tension at the boiling point, and particularly inexpensive hexane, pentane or a mixture thereof is preferable. On the other hand, from the viewpoint of safety, drying from alcohols such as isopropanol, ethanol, butanol, and water or a mixed solvent of water and an organic solvent is preferable. In this embodiment, since the wet gel is entirely held by one structure 19, cracking and shrinkage are suppressed by drying from many solvents such as alcohols and water.

  In the supercritical drying method, since the solvent is removed from the supercritical state without passing through the liquid state, there is no generation of capillary force that occurs only when the gas-liquid interface is formed. As the supercritical fluid used for drying, there are supercritical states such as water, alcohol, carbon dioxide, etc., but carbon dioxide that can be obtained at the lowest temperature and is harmless is preferably used.

  Specifically, by first introducing liquefied carbon dioxide into the pressure vessel, the solvent in the wet gel in the pressure vessel is replaced with liquefied carbon dioxide. Next, the pressure and temperature are raised to a critical point or higher to achieve a supercritical state, and carbon dioxide is gradually released while maintaining the temperature to complete drying.

  The lyophilization method is a drying method in which after the solvent in the wet gel is frozen, the solvent is removed by sublimation. Since it does not go through a liquid state, a gas-liquid interface does not occur in the gel, and capillary force does not work, so that shrinkage of the gel during drying can be suppressed.

  The solvent used in the freeze-drying method is preferably a solvent having a high vapor pressure at the freezing point, and examples thereof include tertiary butanol, glycerin, cyclohexane, cyclohexanol, para-xylene, benzene, and phenol. Among these, tertiary butanol and cyclohexane are particularly preferable because of high vapor pressure at the melting point.

  At the time of lyophilization, it is effective to replace the solvent in the wet gel with a solvent having a high vapor pressure at the above-mentioned freezing point. In addition, it is more preferable to use a solvent having a high vapor pressure at the freezing point as the solvent used for the gelation because the solvent replacement can be omitted and efficient production becomes possible.

  Drying may be performed after the hydrophobizing step or may be performed before the hydrophobizing step. In the case of hydrophobizing after the drying step, hydrophobic groups are introduced on the surface of the dried gel by exposing the dried gel to the vapor of the hydrophobizing agent, not in the solution. Therefore, there is an effect that the amount of solvent to be used is reduced.

  As the hydrophobizing agent used at this time, the above-mentioned hydrophobizing agents can be used, but chlorosilane compounds such as trimethylchlorosilane and dimethyldichlorosilane are most preferable because of their high reactivity. When using a hydrophobizing agent other than the chlorosilane compound, it is also effective to use a catalyst that can be introduced in a gaseous state, such as ammonia or hydrogen chloride.

  Further, when hydrophobizing in the gas phase, the temperature during hydrophobizing can be increased without being limited by the boiling point of the solvent or hydrophobizing agent. Therefore, hydrophobization in the gas phase is effective for speeding up the reaction. Moreover, if the wet gel is a thin film or powder, the penetration of the hydrophobizing agent vapor is easy, and the thin film is more preferable because the effect of reducing the amount of solvent is great.

  Moreover, it is also possible to perform a reconstruction process and a hydrophobization process simultaneously. In this case, since the two steps are simultaneously performed, an effect that a porous body made of a dry gel can be obtained in a short time is obtained.

  Specifically, in the restructuring step and the hydrophobizing step, the wet gel obtained in the first gelation step is immersed in a treatment liquid in which the restructuring gel raw material solution used in the restructuring step and the hydrophobizing agent are mixed. It will be implemented. By doing so, gel reconstruction and hydrophobization proceed simultaneously. As the restructuring material and the hydrophobizing agent at the time of hydrophobization, the same ones as described above can be used. For example, after the first gelation is performed from an aqueous silicic acid solution obtained by electrodialysis from water glass, the obtained wet gel is converted into a gel raw material alkoxysilane and a hydrophobizing agent by using a water-soluble solvent. In a solution in which a silazane compound or the like is dissolved, restructuring and hydrophobization are performed simultaneously.

The joining member 14 is, for example, an adhesive obtained by adding fine particles such as silica and alumina added for viscosity adjustment to the epoxy resin as the main agent, a curing agent, or an organic material such as a sheet-like sheet adhesive at room temperature. Is applicable. Further, it can be used as the bonding member 14 such as a conductive paste obtained by mixing inorganic conductive particles such as silver paste together with a thermosetting resin, or a brazing material such as silver brazing. In the manufacturing method of the ultrasonic transducer 10, first, the acoustic matching layer 11 is adjusted to a thickness of ¼ wavelength, and a bonding member is attached to at least one electrode surface of the piezoelectric body that is the acoustic matching layer 11 or the vibration means 12. The electrode 15 of the vibration means 12 and the acoustic matching layer 11 are bonded together, pressure-fixed with a jig or the like, and put together with the jig in an oven, and the bonding member 14 is cured and bonded. For the bonding member 14, a material that was temporarily reduced in viscosity by heating and penetrated the acoustic matching layer 2 and further cured by heating was selected.

  The operation and action of the ultrasonic transducer 10 configured as described above will be described below. First, by applying a pulse voltage having a frequency of about 200 to 600 KHz to the lead wire 17 and the lead wire 18 from the outside, the piezoelectric body as the vibration means 3 vibrates in the direction perpendicular to the electrode surface and resonates with the vibration. The acoustic matching layer 2 adjusted to the thickness (1/4 wavelength) vibrates, and the vibration is efficiently transmitted from the acoustic matching layer 2 into the air or gas.

  As described above, in the present embodiment, the bonding member 14 penetrates into the voids of the acoustic matching layer 11 that has been hydrophobized, so that the vibration means 12 and the acoustic matching layer 11 are reliably connected, and the efficiency is improved. Therefore, it is an ultrasonic wave transmitter / receiver in which the characteristic variation is small and the characteristic deterioration is small even by the reliability test.

  The ultrasonic transducer formed as described above becomes an acoustic matching layer with low acoustic impedance, which can achieve high sensitivity and stabilization of characteristics, and acoustic matching through reliability tests assuming temperature changes in the usage environment. Even if the layer is deformed, the acoustic matching layer is a relatively soft dry gel, so it does not break and can operate stably over a wide temperature range, so it can be used for a long time and is easy to handle It was possible to provide a simple ultrasonic transducer 1.

(Embodiment 3)
FIG. 10 shows a cross-sectional view of an ultrasonic transducer 35 in the third embodiment of the present invention, and FIG. 11 is a process cross-sectional view showing a method for manufacturing the ultrasonic transducer 35.

  Hereinafter, the manufacturing process of the ultrasonic transducer 35 will be described. Step (a) is a step of forming the acoustic matching layer 37 and is omitted because it is similar to the second embodiment. Step (b) is a piezoelectric body that is the vibration means 36, and is an adhesive that is a bonding member 40 between the surface of the electrode 38 on which the baked silver is formed and the outer wall surface of the ceiling-shaped cylindrical metal case that is the sealed container 42. Is a step of printing. Printing is not limited as long as the adhesive can be printed to a predetermined thickness such as screen printing, gravure printing, and transfer. The celestial cylindrical case is a metal case, and may be anything such as iron, brass, copper, aluminum, alloys thereof, or metals obtained by plating the surfaces of these metals.

  The piezoelectric body, which is the vibration means 3 printed with the adhesive, which is the bonding member 40, is the vibration means 3, and the acoustic matching layer 37 is the vibration wall 3 on the inner wall surface of the ceiling-shaped cylindrical metal case, which is the sealed container 42. Affixed so as to face the piezoelectric body. In such a state, the adhesive is cured while applying pressure. The adhesive is not particularly limited, such as an epoxy resin, a phenol resin, or a cyanoacrylate resin.

  In the step (c), the terminal plate 45 in which the conductive means 44 is inserted is joined to the opening of the dome-shaped cylindrical metal case by welding. The terminal plate 45 includes an electrode terminal 46 and an electrode terminal 47, and is electrically insulated by a terminal plate insulating portion 48. The conductive means 44 is composed of an elastic body such as silicon rubber, butadiene rubber, or elastomer, and a conductive body. The conductive means 44 electrically connects the electrode 39 and the electrode terminal 47, and is a ceiling tube that is the electrode 38 and the sealed container 42. The case and the electrode terminal 46 are electrically connected.

An inert gas is injected into the sealed space 43 formed by the tented cylindrical metal case, which is the sealed container 42, and the terminal plate 45 when welding the tented cylindrical metal case, which is the sealed container 42, and the terminal plate 45. An ultrasonic transceiver 35 was manufactured. The inert gas is not limited as long as it is a gas that does not react with the silver electrode, such as helium gas and nitrogen gas. Piezoelectric body, which is the vibration means 36 provided with silver electrodes, is isolated from the external environment by inserting an inert gas into the celestial cylindrical case at the time of welding, and the electrical connection is stabilized over a long period of time, ensuring long-term reliability. Is done.

  The ultrasonic transducer configured as described above becomes an acoustic matching layer with a low acoustic impedance, can achieve high sensitivity and stabilization of characteristics, and the acoustic matching layer can be obtained through reliability tests assuming temperature changes in the usage environment. Even if it is deformed, the acoustic matching layer is a relatively soft dry gel, so it does not break and can operate stably in a wide temperature range, so it can be used for a long time and is super easy to handle. It has become possible to provide a sonic transducer 35.

(Embodiment 4)
FIG. 12 shows a cross-sectional view of an ultrasonic flow velocity / flow meter according to the fourth embodiment of the present invention.

  In FIG. 12, an ultrasonic transducer 51 and an ultrasonic transducer 52 are arranged diagonally in a flow rate measurement unit 50 in which a fluid flows, which is configured by a flow path 49. L1 shows the transmission path of the ultrasonic wave propagating from the ultrasonic transducer 51 arranged on the upstream side, and L2 shows the ultrasonic transmission path of the ultrasonic transducer 52 arranged on the downstream side. ing.

Let V be the flow velocity of the fluid flowing in the tube, C (not shown) the velocity of the ultrasonic wave in the fluid, and θ be the angle between the direction of flow of the fluid and the propagation direction of the ultrasonic pulse. When the ultrasonic transmitter / receiver 51 is used as an ultrasonic transmitter / receiver and the ultrasonic transmitter / receiver 52 is used as an ultrasonic receiver, an ultrasonic pulse emitted from the ultrasonic transmitter / receiver 51 is converted into the ultrasonic transmitter / receiver 52. The propagation time t1 to reach
t1 = L / (C + V cos θ) (1)
Indicated by

Next, the propagation time t2 at which the ultrasonic pulse from the ultrasonic transducer 52 reaches the ultrasonic transducer 51 is:
t2 = L / (C−Vcos θ) (2)
Indicated by
And if the sound velocity C of the fluid is eliminated from the equations (1) and (2),
V = (L / 2 cos θ) · ((1 / t1) − (1 / t2)) (3)
The following equation is obtained.

  If L and θ are known, the flow velocity V can be obtained by measuring t1 and t2 in the measurement circuit 53. If necessary, the flow rate Q can be obtained by multiplying the flow velocity V by the cross-sectional area S of the flow rate measuring unit 50 and the correction coefficient K. The calculating means 53 calculates Q = KSV.

  By using the ultrasonic transducer of the present invention, it is possible to stabilize the characteristics of the ultrasonic transducer and to operate stably even in the temperature change of the usage environment. A sonic flow velocity / flow meter can be realized.

Sectional drawing of the ultrasonic transducer in Embodiment 1 of this invention Sectional drawing of the ultrasonic transducer 10 in Embodiment 2 of this invention Sectional enlarged view of the acoustic matching layer in Embodiment 2 of the present invention Manufacturing process diagram of one structure in Embodiment 2 of the present invention Manufacturing process diagram of the other structure according to Embodiment 2 of the present invention Molecular arrangement conceptual diagram of organosilane compound in Embodiment 2 of the present invention Molecular arrangement conceptual diagram of organosilane compound in Embodiment 2 of the present invention Conceptual diagram of organosilane compound in silica dry gel production process in Embodiment 2 of the present invention Conceptual diagram of organosilane compound in silica dry gel production process in Embodiment 2 of the present invention Sectional drawing of the ultrasonic transducer in Embodiment 3 of this invention Cross-sectional view of the manufacturing process of the ultrasonic transducer according to the third embodiment of the present invention Sectional drawing of the flow velocity and flowmeter in Embodiment 4 of this invention Cross-sectional view of a conventional ultrasonic transducer

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Ultrasonic transducer 2 Acoustic matching layer 3 Vibrating means 4 Joining member 19 One structure 20 The other structure 37 Acoustic matching layer 35 Ultrasonic transducer 46 Vibrating means 42 Sealed container 50 Flow rate measurement part 51, 52 Sonic transducer 53 Measuring circuit 54 Calculation means

Claims (14)

An ultrasonic transducer in which a bonding member is infiltrated into a hydrophobic porous acoustic matching layer and a vibrating means and an acoustic matching layer are bonded. In the porous body formed of one structure, the other structure is formed in part or all of the voids of the porous body, and the other structure is a porous body having a void smaller than that of the one structure. One structure and the other structure are ultrasonic transducers in which a bonding member is infiltrated into a hydrophobized acoustic matching layer and the vibration means and the acoustic matching layer are bonded. The ultrasonic transducer according to claim 1 or 2, wherein the vibration means is disposed on the inner surface of the sealed container, and the acoustic matching layer is disposed on the outer surface facing the piezoelectric vibrator through the sealed container. The ultrasonic transducer according to claim 1, wherein the joining member is a member that is temporarily reduced in viscosity by heating and hardens. The ultrasonic transducer according to claim 2, wherein the joining member is made of a member containing particles smaller than the voids of the other structure. The ultrasonic transducer according to claim 2, wherein one of the structures is made of ceramic. The ultrasonic transducer according to claim 2, wherein the other structure is made of organic glass. The ceramic introduces bubbles into the ceramic slurry having the hardly fired ceramic powder, the step of gelling the ceramic slurry, the step of drying the gelled ceramic slurry, and the degreasing of the gelled ceramic slurry. The ultrasonic transducer according to claim 6, formed by a step and a step of firing the gelled ceramic slurry. 8. The ultrasonic wave according to claim 7, wherein the organic glass contains a gel obtained by polymerizing and drying a compound represented by the formula (1) or a partially hydrolyzed polymer of the compound represented by the formula (1). Transmitter / receiver.
Formula (1) Si (OR ¹ ) ₄ The organic glass is composed of a hydrolyzable organic group and a non-hydrolyzed group in the presence of a wet gel obtained by polymerizing a compound represented by the formula (1) or a partially hydrolyzed polymer of the compound represented by the formula (1). The transducer according to claim 7, wherein an organosilane compound in which a decomposable organic group is directly bonded to the same silicon is polymerized and dried. The organosilane compound is obtained by polymerizing and drying an organosilane compound in which a hydrolyzable organic group represented by the formulas (2) and (3) and a non-hydrolyzable organic group are directly bonded to the same silicon. The ultrasonic transducer according to claim 10.
Formula (2) R ² Si (OR ¹ ) ₃
Formula (3) (R ² ) ₂ Si (OR ¹ ) ₂ The ultrasonic transducer according to claim 10, wherein the organosilane compound is a linear polysiloxane diol represented by the formula (4).
Formula (4) HO ((R ² ) ₂ SiO) _n H The ultrasonic transducer according to claim 10, wherein the organosilane compound includes a copolymer of at least one of formula (5) and formula (6) and a compound represented by formula (7).
Equation ^{_{(5) CH 2 = CR 3}} (COOR 4)
Here, R ³ represents a hydrogen atom and / or a methyl group.
R ⁴ is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 9 carbon atoms.
Equation ^{_{(6) CH 2 = CR 3}} (COOR 5)
Here, R ⁵ is at least one group selected from the group consisting of an epoxy group, a glycidyl group, and a hydrocarbon group containing at least one of them.
Equation ^{_{(7) CH 2 = CR 3}} (COOR 6)
Here, R ⁶ is a hydrocarbon group containing an alkoxysilyl group and / or a halogenated silyl group. An ultrasonic flowmeter comprising the ultrasonic transducer according to any one of claims 1 to 13, wherein a flow rate measurement unit through which a fluid to be measured flows and the flow rate measurement unit include the flow rate measurement unit. A pair of the ultrasonic transducers disposed opposite to the upstream side and the downstream side of the flow, an ultrasonic propagation time measuring circuit between the pair of ultrasonic transducers, and the target based on the propagation time An ultrasonic flowmeter comprising a calculation means for calculating a flow rate of a measurement fluid.