JP2006226681A - Ultrasonic vibrator, its manufacturing method and ultrasonic flowmeter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high-reliability ultrasonic flowmeter having an acoustic matching layer comprising a ceramic porous body and organic glass fixed by a ring-shaped formwork, concerning an ultrasonic vibrator. <P>SOLUTION: This ultrasonic vibrator 1 is constituted of a rectangular-parallelpiped piezoelectric body 3, and a constitution is formed so that the ceramic porous body 5 and dry gel 6 of the organic glass are surrounded by the ring-shaped formwork, to thereby improve long-term reliability. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an ultrasonic transducer used for an ultrasonic flowmeter for measuring the flow velocity and flow rate of a fluid such as gas or liquid.

  Conventionally, this type of ultrasonic transducer has a configuration as shown in FIG. 8 is a cross-sectional view of the ultrasonic transducer 101, and FIG. 9 is a cross-sectional view of the acoustic matching layer of the ultrasonic transducer.

In the figure, reference numeral 102 denotes a cap-like can case, which houses the piezoelectric body 103. Reference numeral 104 denotes an acoustic matching layer composed of two layers provided on the can case 102. 105 is a ceramic porous body, and 106 is a dry gel of porous organic glass. 107 is a pedestal welded to the can case 102, 108 is a conductive rubber electrically connecting the electrode terminal 109 and the piezoelectric body 103, and 110 is electrically insulating the electrode terminal 109 and the pedestal 107. Reference numeral 111 denotes an enclosing glass portion to be grounded, and reference numeral 111 denotes a ground terminal for electrically connecting the can case 102 and the base 107. Note that electrodes such as baked silver are formed on the upper and lower portions of the piezoelectric body 103 (see, for example, Patent Document 1).
JP 2004-45389 A

  In the conventional ultrasonic transducer 101 having such a configuration, the acoustic matching layer 104 composed of two layers is composed of two layers, a porous organic glass dry gel layer 105, or a part of the porous ceramic 106. Therefore, due to temperature changes such as evaporation drying or thermal cycle during production, due to distortion that seems to be due to differences in thermal expansion coefficient, cracks such as cracks in dry gel 105 of organic glass that is weak in strength, The surface layer was peeled off, and there was a problem in reliability, particularly in long-term reliability. In addition, there is a problem that a corner portion is lost during handling during manufacture.

  The present invention solves the above-mentioned conventional problems, and a ring-shaped formwork is formed around a first matching layer made of a ceramic porous body and a second matching layer made of an organic glass dry gel. An ultrasonic transducer was constructed.

  In order to solve the above-described conventional problems, an ultrasonic transducer of the present invention includes a piezoelectric body bonded in a cap-shaped can case, a first matching layer on a surface of the can case, A ring-shaped mold is provided around the two matching layers, the first matching layer, and the second matching layer, and the ring-shaped mold is applied with compressive stress to the first matching layer and the second matching layer. The configuration is as follows.

  With this configuration, it is possible to suppress the occurrence of distortion due to the difference in thermal expansion coefficient between the ceramic porous body constituting the first layer and the dried organic glass gel constituting the second layer, and excellent long-term reliability. An ultrasonic transducer can be provided. In addition, since the acoustic matching layer is protected by the ring-shaped formwork, it is possible to prevent a part of the acoustic matching layer from being lost due to handling during manufacturing.

  In the ultrasonic transducer of the present invention, the acoustic matching layer composed of two layers is protected by a ring-shaped formwork and compressive stress is applied. Long-term reliability can be ensured without causing peeling of the surface layer. In addition, since the acoustic matching layer is protected by the ring-shaped formwork, it is possible to prevent a part of the acoustic matching layer from being lost due to handling during manufacturing.

  According to a first aspect of the present invention, there is provided a piezoelectric body in which an ultrasonic vibrator is bonded in a cap-shaped can case, a first matching layer provided on the surface of the can case, and a second matching layer. A ring-shaped mold is provided around the layer, the first matching layer, and the second matching layer. With this configuration, the acoustic matching layer is protected by the ring-shaped formwork, compressive stress is applied to the first matching layer and the second matching layer, and the dry gel of organic glass that is weak in strength is cracked. Long-term reliability can be ensured without causing cracks or peeling of the surface layer. In addition, since the acoustic matching layer is protected by the ring-shaped formwork, a part of the acoustic matching layer is not lost due to handling during manufacturing.

In the second invention, in particular, the first matching layer of the first invention is composed of a ceramic porous body. A material having characteristics as a first matching layer having a density of 0.7 to 1.0 [g / cm ³ ] and a speed of sound of 1500 to 2500 [m / s] can be easily obtained by constituting the ceramic porous body. Can do. Also, the strength can be made relatively large, and the second matching layer, which is weak in strength, can be formed while being protected together with the ring-shaped mold.

According to the third aspect of the invention, an ultrasonic vibrator having a high sensitivity can be formed by configuring the second matching layer of the first aspect of the invention with an organic glass dry gel. Since it is protected by the first matching layer and the ring-shaped formwork, the second matching layer having a low strength with a density of 0.25 to 0.35 [g / cm ³ ] and a sound velocity of 200 to 400 [m / s]. And an ultrasonic transducer with high sensitivity can be realized.

  In the fourth invention, the ring form of the first invention is made of resin. As a result, the adhesion with the first matching layer can be improved, the familiarity with the second matching layer can be improved, and the inside can be easily and firmly formed inside. Moreover, unnecessary vibrations generated in the acoustic matching layer can be suppressed, and a high-performance ultrasonic transducer can be realized.

  In the fifth aspect of the invention, the resin of the fourth aspect of the invention is composed of a resin such as PET, polyethylene, vinyl chloride, acrylic, belite, epoxy or the like. With this configuration, it is possible to increase acoustic loss, particularly suppress reverberation that diffuses outside the acoustic matching layer, and realize a high-performance ultrasonic transducer.

  In the sixth aspect of the invention, in particular, the side surface of the mold and the side surface of the can case of the ultrasonic transducer of the first aspect are covered with the second resin. With this configuration, unnecessary vibrations generated in the acoustic matching layer and unnecessary vibrations generated in the can case can be suppressed, and a high-performance ultrasonic transducer can be realized.

  In the seventh invention, in particular, the second resin of the sixth invention is composed of an elastomer resin such as silicon, fluorosilicone, polyimide, fluorine, nitrile rubber, and butyl rubber. With this configuration, the effect of suppressing unnecessary vibration can be increased, and a high-performance ultrasonic transducer can be realized.

  In the eighth invention, in particular, the first matching layer and the second matching layer of the ultrasonic transducer according to the first to seventh inventions are subjected to a hydrophobic treatment. As a result, it is possible to realize a high-performance ultrasonic transducer with excellent long-term reliability.

  A ninth invention provides a pair of the ultrasonic transducers of the first to eighth inventions, transmits ultrasonic waves from one of the ultrasonic transducers, receives by the other ultrasonic transducer, and transmits ultrasonic waves. By providing a time measurement unit that measures the propagation time of the ultrasonic wave from the point to the reception point and a flow rate calculation unit that calculates the flow rate from the propagation time of the ultrasonic wave, an accurate ultrasonic flow meter can be realized.

  The tenth invention is a manufacturing method related to the ultrasonic vibrators of the first to eighth inventions in particular, the step of preparing a dry gel of organic glass, a porous ceramic is prepared and stored in a ring-shaped formwork A step of filling the inside of the porous ceramic and the ring-shaped mold with the organic glass dry gel, a step of hydrophobizing the organic glass dry gel, and a step of forming the second resin on the side surface of the can case Thus, a method for manufacturing an ultrasonic transducer is provided. Thereby, a high-performance ultrasonic transducer with high yield and high reliability can be manufactured.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
FIG. 1 shows a cross-sectional view of an ultrasonic transducer in the first embodiment of the present invention.

  In FIG. 1, an ultrasonic transducer 1 includes a piezoelectric body 3 bonded to an inside of a cap-shaped can case 2 with an epoxy resin and an acoustic matching layer 4 bonded to the outside of the can case 2. It consists of and. The acoustic matching layer 4 has a two-layer configuration including a ceramic porous body portion 5 constituting the first matching layer and an organic glass dry gel portion 6 constituting the second matching layer portion.

  The outer diameter of the ceramic porous body 5 portion was 12 [mm], and the plate thickness was 1.5 [mm]. The portion 6 of the organic glass dry gel had an outer diameter of 12 [mm] and a thickness of 0.5 [mm]. Reference numeral 7 denotes a ring-shaped form, which is provided so as to surround the outer peripheral portion of the acoustic matching layer 4 composed of the ceramic porous body portion 5 and the organic glass dry gel portion 6 in a ring shape.

  The piezoelectric body 3 has a prismatic shape of about 7.4 [mm] square, and electrodes made of baked silver or the like are formed on the upper and lower surfaces (not shown). The pedestal portion 8 is welded to the can case 2 at the peripheral portion to seal the piezoelectric body 3. The conductive rubber 9 electrically connects the lower surface electrode of the piezoelectric body 3 and the terminal 10. The terminal 10 is fixed to the base 8 with an insulating material 11 such as a hermetic seal.

  The other terminal 12 is directly fixed to the base 8 and connected to the upper surface electrode of the piezoelectric body 3 through the can case 2. In this configuration, the ring-shaped formwork is designed to apply residual stress to the acoustic matching layer 4 in the compression direction. That is, tightening stress from the surroundings is always applied to the ceramic porous body portion 5 and the organic gel dry gel portion 6.

  With this configuration, even when the thermal cycle test was performed, no cracks or peeling were observed on the surface of the second matching layer. For this reason, there was no great sensitivity drop.

  FIG. 2 shows the result of the thermal cycle test. In the figure, the horizontal axis represents the number of cycles in the thermal cycle test, and the vertical axis represents the relative sensitivity of the ultrasonic transducer with 1.0 at the start. The thermal cycle test was a method of alternately holding the gas phase between +80 [° C.] and −40 [° C.] for 30 minutes. The white circles in the figure indicate the results (N = 10 average) of the ultrasonic transducers according to the present invention, and the black squares indicate the results of the conventional ultrasonic transducer (N = 10 averages).

  In the ultrasonic transducer according to the present invention, the sensitivity decrease was 5% or less even after 2000 thermal cycles, and there was no one that showed a sensitivity decrease of 10% or more, which was a practical problem. Many conventional ultrasonic transducers deteriorate after 1500 times. At 2000 times, a sensitivity drop of 10% or more, which is a practical problem, occurred. Although several cracks were found on the surface of the ultrasonic transducer according to the present invention, the sensitivity was not lowered. In addition, there was no pit-like peeling on the surface. In conventional ultrasonic transducers, many cracks were observed, and many pit-like peelings on the surface were observed, and the sensitivity was observed to decrease.

  In addition, since the organic glass dry gel portion 6 and the ceramic porous body portion 5 are protected by the ring-shaped formwork, the ridge line portions on the upper surface and the lower surface of the acoustic matching layer during manufacture or operation The work efficiency has been greatly improved. In addition, the thickness of the acoustic matching layer such as sensitivity characteristics can be adjusted efficiently.

The first matching layer is set to a density of 0.7 to 1.0 [g / cm ³ ] and a sound speed of 1500 to 2500 [m / s] from the characteristics such as transmission / reception sensitivity and reception waveform of the ultrasonic transducer. It is required to do. These characteristics can be easily achieved by using a ceramic porous body.

The second matching layer is also set to a density of 0.25 to 0.35 [g / cm ³ ] and a sound speed of 200 to 400 [m / s] from the characteristics such as transmission / reception sensitivity and reception waveform of the ultrasonic transducer. It is required to do. These properties can be easily achieved by using a dry gel of organic glass.

  Next, a ring-shaped formwork will be described. This type of ring-shaped form is required to be flexible and retain residual stress that shrinks. Moreover, when forming organic glass, the thing which swells and shrinks a little after drying is good. These characteristics can be easily achieved by using a resin such as PET, polyethylene, vinyl chloride, acrylic, belite, and epoxy. That is, it was experimentally confirmed that these resin materials are slightly swollen by the organic solvent when forming the organic glass.

  Moreover, when organic glass was dried, it also confirmed experimentally that shrinkage stress remained. Accordingly, when a ring-shaped formwork is also formed using these resins, it is possible to ensure adhesion with the ceramic porous body constituting the acoustic matching layer, and after forming an organic glass and drying, the ceramic porous body and The shrinkage stress is applied to the organic glass dry gel. For this reason, a highly reliable ultrasonic transducer can be realized.

  FIG. 3 is a cross-sectional view of the ultrasonic flowmeter in the present embodiment. In the figure, a pair of ultrasonic transducers 1, 1 are installed on the upstream side and downstream side of the flow path 202 through which the fluid flows so as to face each other with the fluid flow interposed therebetween, and the pair of ultrasonic transducers 1, The flow rate of the fluid was measured from the propagation time of the ultrasonic wave propagating between the two, and the flow rate was calculated from this flow rate value to obtain the ultrasonic flow meter 201.

  In addition, the single arrow 203 (solid line) in a figure shows the direction through which a fluid flows, and the double arrow 204 (broken line) has shown the direction through which an ultrasonic wave propagates. Note that the direction in which the fluid flows and the direction in which the ultrasonic waves propagate intersect at an angle θ.

  Reference numeral 205 denotes a transmission unit that generates a burst signal for driving the transmission-side ultrasonic transducer 1, and 206 denotes a switching unit that switches the signal from the transmission unit 205 to the upstream ultrasonic transducer 1 or the downstream ultrasonic transducer 1. It is.

  The switching unit 206 switches the transmission signal and also performs an operation of switching the reception signal from the upstream ultrasonic transducer 1 or the downstream ultrasonic transducer 1 to the receiving unit 207 configured with an amplifier or the like. Reference numeral 208 denotes a time measurement unit that measures the propagation time of the ultrasonic wave using the signal from the transmission unit 205 and the signal from the reception unit 207, and reference numeral 209 denotes a flow rate calculation unit that calculates the flow rate of the fluid from the propagation time of the ultrasonic wave.

  The ultrasonic flowmeter 201 propagates ultrasonic waves from the ultrasonic transducer 1 on the upstream side to the ultrasonic transducer 1 on the downstream side, and determines the ultrasonic propagation time Tud and the ultrasonic transducer 1 on the downstream side. The ultrasonic wave is propagated from the ultrasonic wave to the ultrasonic transducer 1 on the upstream side, the ultrasonic wave propagation time Tdu is measured alternately, the time difference is calculated using the measured ultrasonic wave propagation times Tud, Tdu, and the flow velocity and flow rate are calculated. To do.

  In this configuration, for example, ultrasonic waves are transmitted from the upstream ultrasonic transducer 1 and received by the downstream ultrasonic transducer 1. The zero cross point that comes next to the point where the received wave crosses the reference level is the reception time point, and the time from the start point of the transmission wave to this zero cross point is the ultrasonic wave propagation time Tud. Similarly, the switching unit 206 is operated to measure the ultrasonic propagation time Tdu from the downstream ultrasonic transducer 1 to the upstream ultrasonic transducer 1. Using the ultrasonic propagation times Tud and Tdu thus obtained, the flow rate of the fluid was calculated by the flow rate calculation unit 209 as follows.

The propagation time of ultrasonic waves from the ultrasonic transducer 1 on the upstream side to the ultrasonic transducer 1 on the downstream side is Tud, and the propagation of ultrasonic waves from the ultrasonic transducer 1 on the downstream side to the ultrasonic transducer 1 on the upstream side is If the time is Tdu, the propagation velocity of ultrasonic waves in the fluid is Vs, and the fluid flow velocity is Vf,
Tud = Ld / [Vs + Vf · cos (θ)],
Tdu = Ld / [Vs−Vf · cos (θ)]
It becomes. Ld represents the distance between the ultrasonic transducers 1 and 1.

From these,
Vs + Vf · cos (θ) = Ld / Tud,
Vs−Vf · cos (θ) = Ld / Tdu
And subtracting both sides,
2 * Vf · cos (θ) = (Ld / Tud) − (Ld / Tdu)
= Ld * [(1 / Tud)-(1 / Tdu)]
It becomes.

Therefore,
Vf = {Ld / [2 · cos (θ)]} * [(1 / Tud) − (1 / Tdu)]
Thus, the fluid flow velocity Vf can be obtained. Further, the flow rate Qm is obtained by multiplying the cross-sectional area Sr of the flow path 202. That is, Qm = Sr * Vf is the measured flow rate value.

  As described above, according to the present embodiment, the ultrasonic propagation time is measured using the ultrasonic reception waveform from the upstream to the downstream or from the downstream to the upstream, so that a highly accurate ultrasonic flowmeter 201 is realized. it can.

(Embodiment 2)
FIG. 4 is a cross-sectional view of the ultrasonic transducer 13 according to the second embodiment of the present invention.

  Reference numeral 14 denotes a cylindrical resin layer, which is configured to cover the periphery of the acoustic matching layer 16 having the ring-shaped mold 15 and the periphery of the can case 17. It has been found that this configuration suppresses unnecessary vibration that occurs when the ultrasonic transducer is driven. As this type of material, an elastomer resin such as silicon, fluorosilicone, polyimide, fluorine, nitrile rubber, butyl rubber, that is, a material having high flexibility is suitable.

  FIG. 4 shows the impedance characteristics of the ultrasonic transducer. FIG. 5A shows the resistance component of the impedance characteristic, the horizontal axis shows the frequency, the region of about 100 to 900 [kHz], and the vertical axis shows the logarithm of the resistance value. FIG. 5B shows the phase component of the impedance characteristic, the horizontal axis shows the frequency, the region of about 100 to 900 [kHz], the vertical axis shows the phase, and about −90 to +90 [deg]. Indicates the area. Reference numerals 18 and 19 denote two resonance points, and 20 denotes an anti-resonance point. A circle 21 in FIG. 5B indicates the disturbance of the impedance characteristic due to unnecessary vibration.

  FIG. 6 shows an enlarged view of the circle 21. FIG. 6A shows the impedance characteristics when there is no ring-shaped mold and a cylindrical resin layer, and FIG. 6B shows the case where a ring-shaped mold is mounted and there is no cylindrical resin layer. FIG. 6C shows the impedance characteristics when a ring-shaped formwork and a cylindrical resin layer are mounted. The dotted circle 22a in FIG. 6 (a) The dotted circle 23a in FIG. 6 (b) In the order of the dotted circle 24 in FIG. 6 (c), the smoothness of the impedance curve increases greatly. I understand.

  That is, when the ultrasonic vibrator has a lot of unnecessary vibration and is strongly present, the impedance curve shows a steep change and becomes a non-smooth curve as shown in FIG. As unnecessary vibration is suppressed, the impedance curve becomes smoother. By configuring the ring-shaped formwork with resin such as PET, polyethylene, vinyl chloride, acrylic, belite, epoxy, etc., which has poor acoustic characteristics, the unnecessary vibration generated when the ultrasonic vibrator is driven is slightly suppressed. It can be seen that In addition, when an ultrasonic vibrator is driven by forming a cylindrical resin layer using elastomeric resin such as silicon, fluorosilicone, polyimide, fluorine, nitrile rubber, butyl rubber, etc. It turns out that the unnecessary vibration which generate | occur | produces is suppressed significantly.

(Embodiment 3)
Below, the manufacturing method of the ultrasonic transducer | vibrator based on this invention is demonstrated.

  First, the ceramic porous body of the 1st matching layer which comprises this kind of acoustic matching layer is demonstrated. It is important that the characteristics required for the ceramic porous body are large porosity, uniform pore distribution, and communication holes. In order to form such a ceramic porous body, a sol casting method in which a ceramic slurry containing a large amount of air bubbles is solidified and fired is suitable. The process of the sol casting method will be briefly described. First, a ceramic powder raw material and a gelling material containing a crosslinking agent, a catalyst, a surfactant and the like are sufficiently mixed. At this time, water or an organic solvent may be used as the mixing medium. In this way, a ceramic library is formed. At this time, a dispersant, a lubricant, a thickener, a paste, or the like may be added.

  Next, a foaming agent is added to the ceramic slurry, stirred and mixed, and a predetermined amount of foam is introduced into the slurry. If the ceramic slurry is sufficiently deaerated before introducing bubbles, the amount of bubbles introduced is stabilized. The ceramic slurry into which bubbles have been introduced in this manner is placed in a mold so as to have the shape shown in FIG. The ceramic porous body is fired at a predetermined temperature and time in order to remove the mold after drying and burn off organic substances such as surfactants to form communication holes. At this time, when an oxide-based material such as alumina, mullite, or zirconia is used as the ceramic powder material, this kind of ceramic porous body can be formed by a sol-casting method relatively easily.

  In addition, this kind of ceramic porous body can be formed by a sol-casting method relatively easily using non-oxide ceramic materials such as silicon carbide, silicon nitride, aluminum nitride, boron nitride, and graphite. Can be formed.

Next, the second matching layer will be described. Also for the second matching layer, the density is set to 0.25 to 0.35 [g / cm ³ ] and the sound speed is set to 200 to 400 [m / s] from the characteristics such as transmission / reception sensitivity and reception waveform of the ultrasonic transducer. Is required. These properties can be easily achieved by using a dry gel of organic glass.

  Below, the dry gel of the organic glass which comprises this kind of acoustic matching layer is demonstrated.

  The organic glass dry gel as the acoustic matching layer is required to have a low sound speed and a low density. An organic synthesis method is suitable for forming such a dry gel of organic glass. First, a raw material glass material such as ethoxysilane or methoxysilane is dispersed in an alcohol solvent such as methyl or ethyl in a sufficiently active state using a catalyst. This solution is added with a catalyst such as aqueous ammonia to be used as a raw material for organic glass, impregnated in a sufficiently degassed ceramic porous body, and aged to obtain a wet gel of organic glass containing a large amount of solvent. This is shown in FIG. 25 is a ceramic porous body, 26 is a ring-shaped mold, 27 is a jig on a Teflon (registered trademark) perforated disk to which gel is not fixed, and 28 is a base made of Teflon (registered trademark). , 29 is an upper lid made of Teflon (registered trademark). As explained above, in this state, it is sufficiently degassed, an organic glass raw material is injected, and after waiting for gelation, a wet gel is obtained.

  This wet gel is formed inside the ceramic porous body and in the space surrounded by the ring-shaped mold shown by 30 in FIG. In this way, the wet gel is continuously formed in and on the ceramic porous body. The organic glass formed continuously in this manner is firmly adhered to the ceramic porous body and the ring-shaped mold, and can function as a highly reliable acoustic matching layer. The solvent inside the wet gel is dried to obtain a dried organic glass. In this way, an organic glass having a low sound speed and low density is formed.

  In order to further improve the reliability, the acoustic matching layer including the first matching layer, the second matching layer, and the ring-shaped mold is subjected to a hydrophobic treatment. The hydrophobic treatment is performed using a silane coupling agent. As a result, it is possible to realize an ultrasonic transducer having stable characteristics without suppressing infiltration into moisture under high humidity conditions and without causing condensation inside.

Even when organic glass was formed on a ceramic porous body without a ring-shaped mold, the adhesive strength was weak, so that it often occurred during use as an acoustic matching layer. In addition, corners such as the upper and lower surfaces may be damaged during handling.
In this way, a ring-shaped mold is provided on the outer peripheral portion of the ceramic porous body, and an organic glass is continuously formed from the inside of the ceramic porous body to obtain a highly reliable acoustic matching layer. In order to do so, it is essential.

  It should be noted that this kind of organic glass can be obtained in the same manner as described above even when titanium oxide, zirconia, alumina, or the like other than the above-described silicon oxide type is used.

  As described above, the ultrasonic transducer according to the present invention has a configuration in which the first matching layer and the second matching layer made of the dried organic glass gel and the ceramic porous body are surrounded by the ring-shaped mold. Therefore, it is possible to realize an ultrasonic vibrator that has high ultrasonic sensitivity and is less susceptible to cracking or peeling even in a thermal cycle and has excellent long-term reliability. Moreover, it can be manufactured with good yield without being damaged during handling.

  Therefore, the ultrasonic transducer of the present invention can be applied to uses such as an ultrasonic flow meter.

Sectional drawing of the ultrasonic transducer | vibrator in Embodiment 1 of this invention The characteristic view which shows the result of the thermal cycle test in Embodiment 1 of this invention Block diagram of the embodiment Sectional drawing of the ultrasonic transducer | vibrator in Embodiment 2 of this invention Impedance characteristic diagram according to Embodiment 2 of the present invention Enlarged view of impedance characteristics in the second embodiment of the present invention Layout at the time of manufacture in Embodiment 3 of the present invention Cross-sectional view of a conventional ultrasonic transducer Sectional view of a conventional acoustic matching layer

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Ultrasonic vibrator 2 Can case 3 Piezoelectric body 4 Acoustic matching layer 5 Ceramic porous body 6 Dry gel of organic glass 7 Ring-shaped formwork

Claims (10)

A piezoelectric body bonded in a cap-shaped can case, a first matching layer and a second matching layer provided on the surface of the can case, the first matching layer, and the second matching layer. An ultrasonic transducer having a ring-shaped form around the matching layer. The ultrasonic transducer according to claim 1, wherein the first matching layer is a ceramic porous body. The ultrasonic transducer according to claim 1, wherein the second matching layer is an organic glass dry gel. The ultrasonic transducer according to claim 1, wherein the ring-shaped formwork is made of resin. The ultrasonic transducer according to claim 4, wherein the ultrasonic transducer is made of a resin such as PET, polyethylene, vinyl chloride, acrylic, belite, epoxy, or the like. 2. The ultrasonic transducer according to claim 1, wherein the side surface of the mold and the side surface of the can case are coated with a second resin. The ultrasonic vibrator according to claim 6, wherein the second resin is made of an elastomer resin such as silicon, fluorosilicone, polyimide, fluorine, nitrile rubber, or butyl rubber. The ultrasonic transducer according to claim 1, wherein the first matching layer and the second matching layer are hydrophobized. A pair of the ultrasonic transducers according to claim 1 is provided, ultrasonic waves are transmitted from one of the ultrasonic transducers, received by the other ultrasonic transducer, and from the transmission of ultrasonic waves to the reception point. An ultrasonic flowmeter comprising: a time measuring unit that measures a propagation time of a sound wave; and a flow rate calculation unit that calculates a flow rate from the propagation time of the ultrasonic wave. It is a manufacturing method of the ultrasonic transducer | vibrator in any one of Claims 1-8, Comprising: The process of preparing the dry gel single-piece | unit of organic glass, the process of preparing a porous ceramic, and accommodating in a ring-shaped formwork Filling the inside of the porous ceramic and the ring-shaped mold with the organic glass dry gel, hydrophobizing the organic glass dry gel, and forming the second resin on the side surface of the can case. A method for manufacturing an ultrasonic transducer, comprising:

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