WO2015198386A1 - Ultrasonic flowmeter and method for manufacturing same - Google Patents

Ultrasonic flowmeter and method for manufacturing same Download PDF

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Publication number
WO2015198386A1
WO2015198386A1 PCT/JP2014/066628 JP2014066628W WO2015198386A1 WO 2015198386 A1 WO2015198386 A1 WO 2015198386A1 JP 2014066628 W JP2014066628 W JP 2014066628W WO 2015198386 A1 WO2015198386 A1 WO 2015198386A1
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WO
WIPO (PCT)
Prior art keywords
ultrasonic
thin film
bottom member
tube wall
metal thin
Prior art date
Application number
PCT/JP2014/066628
Other languages
French (fr)
Japanese (ja)
Inventor
宮本年昭
村井勇気
Original Assignee
本多電子株式会社
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Filing date
Publication date
Application filed by 本多電子株式会社 filed Critical 本多電子株式会社
Priority to JP2016528778A priority Critical patent/JP6326610B2/en
Priority to PCT/JP2014/066628 priority patent/WO2015198386A1/en
Publication of WO2015198386A1 publication Critical patent/WO2015198386A1/en

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
    • G01F1/66—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by measuring frequency, phase shift or propagation time of electromagnetic or other waves, e.g. using ultrasonic flowmeters

Definitions

  • the present invention relates to an ultrasonic flowmeter that measures the flow rate of a fluid using ultrasonic waves, and a method for manufacturing the ultrasonic flowmeter.
  • an ultrasonic flowmeter is used to manage the flow rate of a chemical solution (fluid) such as hydrofluoric acid or sulfuric acid.
  • a chemical solution such as hydrofluoric acid or sulfuric acid.
  • the ultrasonic flowmeter it has piping which flows the chemical
  • the flow rate of industrial fluid is obtained.
  • a fluororesin excellent in chemical resistance is used as a pipe for flowing a chemical solution.
  • a chemical solution at a high temperature (100 ° C. to 200 ° C.) is used to increase the efficiency of the polishing process.
  • a special chemical solution such as hydrofluoric acid or sulfuric acid is used at a high temperature
  • the gasified chemical solution permeates the fluororesin in the pipe and permeates the ultrasonic transducer side. The penetration of the chemical solution corrodes the electrode and the like, thereby shortening the life of the ultrasonic flowmeter.
  • a resin holder is formed into a bottomed cylinder using tetrafluoroethylene / perfluoroalkoxyethylene (PFA) which is a fluororesin, and an ultrasonic wave is formed at the bottom of the resin holder.
  • PFA perfluoroalkoxyethylene
  • a vibrator is arranged.
  • a non-gas-permeable metal thin film is formed on the surface (inner surface or outer surface) of the resin holder, and the metal thin film prevents liquid vaporized gas from penetrating into the inside through the bottom of the resin holder. It comes to stop.
  • a fluororesin (PFA) having excellent chemical resistance is used as a resin holder forming material. Has the property of being difficult to adhere. For this reason, it is difficult to form a metal thin film having sufficient adhesion strength on the surface of the resin holder.
  • PFA fluororesin
  • the present invention has been made in view of the above problems, and an object of the present invention is to provide an ultrasonic flowmeter that can reliably prevent corrosion of electrodes and wiring of an ultrasonic transducer and improve product life. There is. Another object is to provide an ultrasonic flowmeter manufacturing method capable of efficiently and reliably manufacturing an ultrasonic flowmeter having a long product life.
  • the invention according to claim 1 is characterized in that a resin-made flowmeter body having a tube forming a flow path through which a fluid flows, and an upstream position and a downstream position in the flow path, respectively.
  • a pair of ultrasonic transducers that are positioned opposite to each other across a tube wall and that transmit and receive ultrasonic waves through the tube wall, and a bottomed cylindrical member made of a rigid body, the ultrasonic vibration
  • a pair of transducer holders mounted on the outside of the tube wall in a state in which each of the children is housed, and based on a difference in propagation time of ultrasonic waves transmitted and received between the pair of ultrasonic transducers,
  • An ultrasonic flow meter for measuring the flow rate of the transducer holder, wherein the transducer holder has a side surface, an inner bottom surface to which the ultrasonic transducer is fixed, and an outer bottom surface located on the opposite side of the inner bottom surface.
  • the non-gas permeable metal thin film is formed so as to cover at least a region extending from the outer bottom surface of the bottom member through the side surface of the bottom member to the joint portion of the bottom member and the cylindrical member.
  • the pair of transducer holders each accommodating the ultrasonic transducer are mounted on the outside of the tube wall.
  • the pair of ultrasonic transducers housed in each transducer holder is in a positional relationship in which the ultrasonic transducers are opposed to each other across the tube wall at the upstream position and the downstream position in the flow path.
  • the velocity of the fluid can be obtained based on the difference in propagation time, and the flow rate of the fluid can be measured based on the velocity of the fluid.
  • a fluid that causes corrosion for example, a chemical solution such as sulfuric acid or hydrofluoric acid
  • a resin having excellent chemical resistance for example, Even if the flowmeter body is formed using a fluororesin
  • the liquid vaporized gas may permeate the tube wall (resin portion) of the flow path when the concentration or temperature of the fluid increases.
  • a metal thin film is formed on the outer surface of the vibrator holder so as to cover at least a region extending from the outer bottom surface of the bottom member through the side surface of the bottom member to the joint portion between the bottom member and the cylindrical member. .
  • the metal thin film blocks gas penetration into the vibrator holder.
  • the metal thin film is formed not on the resin flowmeter main body side but on the surface of a rigid vibrator holder (bottom member and cylindrical member).
  • the outer surface of the vibrator holder is unlikely to undergo thermal expansion like the resin surface, so it is ensured that the metal thin film is in close contact with the outer face of the vibrator holder. Retained. As a result, even when the ultrasonic flowmeter is used for a long period of time, corrosion of the ultrasonic vibrator or the like can be avoided by the metal thin film. Further, in the vibrator holder, the ultrasonic vibrator is fixed to the inner bottom surface of the bottom member, and the outer bottom surface of the bottom member is pressed against the tube wall side by the cylindrical member joined to the outer edge portion of the inner bottom surface. .
  • this bottom member is interposed between the ultrasonic transducer and the tube wall and functions as an acoustic matching layer, the ultrasonic wave output from the ultrasonic transducer can be efficiently propagated to the fluid through the tube wall. And the fluid flow rate can be measured accurately.
  • the gist of the invention described in claim 2 is that, in claim 1, the metal thin film is formed on the entire outer surface of the vibrator holder.
  • the metal thin film is formed on the entire outer surface of the vibrator holder, thereby reliably preventing corrosion of the electrodes and wiring of the ultrasonic vibrator in the vibrator holder. can do.
  • the metal thin film can function as a shield layer, and electrical noise can be prevented from being superimposed on the output signal of the ultrasonic transducer.
  • the gist of the invention described in claim 3 is that, in claim 1, the metal thin film is formed on the entire outer surface and the entire inner surface of the vibrator holder.
  • the metal thin film is formed twice on the entire outer surface and the entire inner surface of the vibrator holder, the electrodes and wiring of the ultrasonic vibrator in the vibrator holder, etc. Corrosion can be prevented more reliably. Further, in this case, since the ultrasonic vibrator, the wiring and the like are protected by the double shield structure, the shielding effect against electric noise can be enhanced.
  • the gist of the invention of claim 4 is that, in any one of claims 1 to 3, the metal thin film is made of gold or platinum.
  • a fluid that causes corrosion for example, a chemical solution such as hydrofluoric acid or sulfuric acid
  • a chemical solution such as hydrofluoric acid or sulfuric acid
  • the bottom member is a ceramic having an acoustic impedance smaller than that of the ultrasonic transducer and larger than that of the tube wall. The gist.
  • the difference in acoustic impedance at the interface between each member can be reduced by interposing the bottom member between the ultrasonic transducer and the tube wall. For this reason, an ultrasonic wave can be efficiently and reliably propagated to the liquid flowing through the flow path.
  • a sixth aspect of the present invention is the flowmeter of the flowmeter main body according to any one of the first to fifth aspects, wherein the flowmeter body has a straight pipe portion extending straight and both ends of the straight pipe portion are The gist is that the pipe is bent at a right angle, and the pair of ultrasonic transducers is provided at each of the upstream and downstream ends of the straight pipe portion.
  • ultrasonic waves are transmitted and received through the fluid flowing through the straight pipe portion, and in the forward and reverse directions with respect to the liquid flow.
  • the propagation time when the ultrasonic wave propagates is measured.
  • the flow rate of the liquid can be obtained from the difference between the propagation times, and the flow rate of the liquid can be measured by converting the flow rate into a flow rate.
  • the gist of the invention according to claim 7 is that, in any one of claims 1 to 6, the surface of the bottom member has a surface roughness value larger than that of the outer surface of the tube wall.
  • a metal thin film having high adhesion strength (peel strength) and difficult to peel can be reliably formed on the surface (side surface and outer bottom surface) of the bottom member.
  • the gist of the invention according to claim 8 is that, in any one of claims 1 to 7, the bottom member has a thickness of ⁇ / 4 corresponding to the wavelength ⁇ of the ultrasonic wave.
  • the bottom member can function as an acoustic matching layer, and ultrasonic waves can be efficiently propagated to the liquid through the tube wall.
  • the gist of a ninth aspect of the present invention is that, in any one of the first to eighth aspects, the metal thin film is formed to be thinner than 1 / of the wavelength ⁇ of the ultrasonic wave. .
  • the ultrasonic wave is not reflected on the surface of the metal thin film, and the propagation of the ultrasonic wave is not affected. Furthermore, the material cost of the metal thin film can be kept low.
  • a tenth aspect of the present invention is the rubber sheet according to any one of the first to ninth aspects, wherein the outer bottom surface on which the metal thin film is formed in the vibrator holder has a heat resistance and a chemical resistance.
  • the gist is to be in close contact with the tube wall through the buffer member.
  • the outer bottom surface of the bottom member is brought into close contact with the tube wall via the sheet-like buffer member, the ultrasonic wave can be reliably propagated.
  • the grease cannot maintain its shape when used at a high temperature for a long time. May decrease.
  • the sheet-like buffer member having heat resistance and chemical resistance is used, the outer bottom surface of the bottom member is not affected by deterioration of the buffer member even when used for a long period of time. Can be securely adhered to each other.
  • the invention described in claim 11 is a method of manufacturing the ultrasonic flowmeter according to any one of claims 1 to 10, wherein the cylindrical member and the bottom member are joined using an adhesive.
  • the gist of the manufacturing method of the ultrasonic flowmeter is as follows.
  • the thin film forming step is performed after the tubular member and the bottom member are joined to form the bottomed tubular vibrator holder.
  • the metal thin film can be reliably formed so as to block the joint portion between the tubular member and the bottom member.
  • liquid vaporized gas can be prevented from entering the vibrator holder by the metal thin film, and corrosion of electrodes and wiring of the ultrasonic vibrator housed in the vibrator holder can be avoided. Therefore, according to the present invention, an ultrasonic flowmeter having a long product life can be manufactured efficiently and reliably.
  • An ultrasonic flow meter 10 shown in FIG. 1 is provided in the middle of a chemical solution supply line of a CMP (Chemical Mechanical Polishing) device, and measures the flow rate of the chemical solution W1 (fluid) supplied to the CMP device.
  • the chemical liquid W1 supplied to the CMP apparatus is hydrofluoric acid or sulfuric acid
  • the liquid temperature of the chemical liquid W1 is a temperature of 100 ° C. or higher and 200 ° C. or lower.
  • the ultrasonic flowmeter 10 has a resin-made flowmeter body 13 having a pipe 12 forming a flow path 11 through which a chemical solution W1 flows, and a pipe wall 14 at an upstream position and a downstream position in the flow path 11. And a pair of ultrasonic transducers 16 in a positional relationship facing each other.
  • the flow path 11 of the flow meter body 13 is a liquid pressure-feeding pipe connected to the chemical liquid circulation line, and is formed in a U shape along the flow direction. That is, the flow channel of the flowmeter body 13 has a straight pipe portion 18 extending straight and both ends of the straight pipe portion 18 are bent at right angles in the same direction (upper side in FIG. 1). It is.
  • a pair of ultrasonic transducers 16 are provided at the upstream and downstream ends of the straight pipe portion 18 of the flow path 11.
  • the flow meter body 13 is formed using a fluororesin (specifically, PFA) having excellent heat resistance and chemical resistance, and the length of the straight pipe portion 18 is about 10 cm.
  • PFA fluororesin
  • the cross-sectional shape of the flow path 11 formed in the pipe 12 of the flow meter main body 13 is circular, and the aperture is about 6 mm.
  • the ultrasonic flowmeter 10 of the present embodiment is a bottomed cylindrical member made of a rigid body, and the flowmeter main body 13 in a state in which the ultrasonic transducer 16 is housed. And a pair of vibrator holders 20 to be mounted on. More specifically, the vibrator holder 20 of the present embodiment is formed into a bottomed cylindrical shape by a cylindrical tube member 21 and a disk-shaped bottom member 22 (see FIG. 5). Further, in the flow meter main body 13, receiving recesses 23 are formed on the outer sides of the tube walls 14 positioned at both ends of the straight pipe portion 18.
  • the bottom member 22 of the vibrator holder 20 is directed to the straight pipe portion 18 (tube wall 14) side, and the bottom member 22 is passed through the buffer member 24 to the tube wall 14 of the flow path 11.
  • the vibrator holder 20 is housed in a state where the vibrator holder 20 is in contact therewith.
  • the buffer member 24 is a rubber sheet-like member formed using a material having excellent heat resistance and chemical resistance (such as silicone rubber or fluoro rubber).
  • the buffer member 24 has a thickness that does not affect the propagation of ultrasonic waves (for example, a thickness of about 200 ⁇ m), and is formed thinner than the bottom member 22.
  • grease for example, silicone grease
  • the cylindrical member 21 constituting the vibrator holder 20 is made of a copper pipe functioning as a shield member, and has an outer diameter of about 12.5 mm and a length of about 15 mm. Further, the inner diameter of the cylindrical member 21 is slightly larger than the diameter of the ultrasonic transducer 16. In a state where the ultrasonic transducer 16 is accommodated inside the cylindrical member 21, a gap is formed between the inner surface of the cylindrical member 21 and the side surface of the ultrasonic transducer 16.
  • the bottom member 22 constituting the vibrator holder 20 is a silica-based ceramics containing silica (SiO 2 ), and includes a side face 26, an inner bottom face 27 to which the ultrasonic vibrator 16 is fixed, and an inner bottom face. 27 is formed in a disk shape having an outer bottom surface 28 located on the opposite side of 27 (see FIG. 5 and the like).
  • the bottom member 22 has a larger diameter than the ultrasonic transducer 16 (a diameter of about 12.5 mm, which is equal to the cylindrical member 21). And in the inner bottom face 27 of the bottom member 22, the edge part 29 of the cylinder member 21 is joined to the outer edge part outside the fixing part of the ultrasonic transducer
  • the ultrasonic transducer 16 of the present embodiment is made of, for example, lead zirconate titanate (PZT), and is formed in a disk shape having a diameter of about 10 mm and a thickness of about 1.0 mm. As shown in FIGS. 3 and 4, the ultrasonic transducer 16 has a first main surface 31 and a second main surface 32 provided on the back side thereof. A pair of electrodes 33 and 34 each having a folded electrode 33 a is provided on each of the main surfaces 31 and 32 of the ultrasonic transducer 16.
  • PZT lead zirconate titanate
  • a first electrode 33 (ground electrode) is provided on the first main surface 31 side, and the surface of the first electrode 33 is the bottom member 22 of the transducer holder 20. It is bonded and fixed to the inner bottom surface 27 (see FIG. 5).
  • a part 33 a of the first electrode 33 and a second electrode 34 (working electrode) folded from the first main surface 31 side are provided on the second main surface 32 side. Yes.
  • Each electrode 33, 34 is formed using silver.
  • the ground line 36 is connected to the electrode 33 a on the second main surface 32 side of the ultrasonic transducer 16 and the signal line 37 is connected to the second electrode 34.
  • the electrode 33a and the electrode 34 are provided at predetermined intervals, and these electrodes are insulated (refer FIG.3 and FIG.4).
  • the entire first main surface 31 is bonded to the bottom member 22 of the transducer holder 20, and the first main surface 31 emits ultrasonic waves. It functions as an acoustic radiation surface.
  • the bottom member 22 interposed between the tube wall 14 of the flow path 11 and the ultrasonic transducer 16 and bonded to the acoustic radiation surface (first main surface 31) of the ultrasonic transducer 16 serves as an acoustic matching layer. Function. That is, the bottom member 22 is a member having an acoustic impedance smaller than that of the ultrasonic transducer 16 and larger than that of the tube wall 14 and efficiently propagates ultrasonic waves.
  • the acoustic impedance of the ultrasonic transducer 16 is 30.0 ⁇ 10 6 N ⁇ s / m 3
  • the acoustic impedance of the bottom member 22 is 12.5 ⁇ .
  • 10 6 N ⁇ s / m 3 and the acoustic impedance of the tube wall 14 (PFA) is 2.6 ⁇ 10 6 N ⁇ s / m 3 .
  • the resonance frequency f of the ultrasonic transducer 16 is 2 MHz
  • the sound velocity v in the bottom member 22 is about 5000 m / s.
  • the adhesive layer (not shown) interposed between the ultrasonic transducer 16 and the bottom member 22 has a thickness (thickness of about several tens of ⁇ m) that does not affect the propagation of the ultrasonic waves. It is formed thinner than.
  • the bottom member 22 is joined to the other side (lower side in the drawing) and the other side (upward side in the drawing) located on the opposite side.
  • a U-shaped cutout portion 40 is formed on the end portion 30 side so as to extend from the end portion 30 to the one end portion 29 side.
  • two elongated slit grooves 41 are formed at positions facing the U-shaped notch 40 in the cylindrical member 21.
  • a ground wire 36 is soldered to a portion sandwiched between the two slit grooves 41 on the inner surface of the cylindrical member 21.
  • the conductor portion 36a is exposed by removing a part of the coating in the middle of the ground wire 36 connected to the electrode 33a of the ultrasonic transducer 16, and the exposure is performed.
  • the conducting wire portion 36a is solder-connected to the cylindrical member 21.
  • a disk-shaped lid member 43 made of copper closes the opening of the end 30 at the end 30 where the notch 40 and the slit groove 41 are formed.
  • the cylindrical member 21, the bottom member 22, and the lid member 43 are disposed so as to surround the ultrasonic transducer 16.
  • a coaxial cable receptacle 45 is disposed in the notch 40 of the cylindrical member 21.
  • the receptacle 45 according to the present embodiment is an SMB specification receptacle, and is fixed to the flow meter main body 13 using a receptacle fixing nut 46, a receptacle washer 47, and the like.
  • a coaxial plug 49 attached to the tip of the coaxial cable 48 is coupled to the receptacle 45.
  • the coaxial plug 49 is a plug-type SMB coaxial connector that can be coupled to the receptacle 45. Further, in the flow meter main body 13, a bottomed two-stage cylindrical cover member 51 is mounted so as to cover the coupling portion between the receptacle 45 and the coaxial plug 49.
  • the cover member 51 is formed using a fluororesin (for example, PFA) that is excellent in heat resistance and chemical resistance, similarly to the flow meter main body 13.
  • the central conductor 53 of the receptacle 45 and the second electrode 34 of the ultrasonic transducer 16 are connected via a signal line 37.
  • the ground conductor 54 of the receptacle 45 is connected to the cylindrical member 21 and a part 33 a of the first electrode 33 of the ultrasonic transducer 16 via the ground line 36.
  • the first electrode 33 (ground electrode), the cylindrical member 21, and the lid member 43 of the ultrasonic transducer 16 are set to the same potential (ground potential).
  • the signal line 37 is disposed in a space surrounded by the grounded conductor 54 of the first electrode 33, the cylindrical member 21, the lid member 43, and the receptacle 45, all of which are grounded. Yes. Therefore, it is possible to effectively prevent noise from being superimposed on the signal of the signal line 37, that is, the output signal of the ultrasonic transducer 16.
  • a pressing lid 57 is disposed on the outside (right side in FIG. 2) of the lid member 43 of the vibrator holder 20 via a wave washer 56.
  • the presser lid 57 is screwed into the housing recess 23 of the flow meter main body 13 and presses the vibrator holder 20 via the wave washer 56.
  • the outer bottom surface 28 of the bottom member 22 is pressed against the tube wall 14 side of the flow path 11 through the cylindrical member 21.
  • the bottom member 22 (acoustic matching layer) of the vibrator holder 20 is brought into close contact with the tube wall 14 of the flow path 11 via the buffer member 24.
  • a non-gas permeable metal thin film 61 is formed on the outer surface 58 of the vibrator holder 20, at least a region extending from the outer bottom surface 28 of the bottom member 22 through the side surface 26 of the bottom member 22 to the joint portion 60 between the bottom member 22 and the cylindrical member 21 is covered.
  • a non-gas permeable metal thin film 61 is formed on the outer surface 58 of the vibrator holder 20, at least a region extending from the outer bottom surface 28 of the bottom member 22 through the side surface 26 of the bottom member 22 to the joint portion 60 between the bottom member 22 and the cylindrical member 21 is covered.
  • a non-gas permeable metal thin film 61 is formed.
  • the metal thin film 61 covers the entire outer bottom surface 28 of the bottom member 22 and the entire side surface 26 of the bottom member 22, and the cylindrical member with reference to the joint portion 60 between the bottom member 22 and the cylindrical member 21.
  • the outer surface 62 of the cylindrical member 21 is covered to a position of about several mm on the 21 side.
  • the metal thin film 61 in the present embodiment is a thin film made of a metal material (specifically, gold or platinum) having excellent corrosion resistance, and has a thickness of about several ⁇ m.
  • the metal thin film 61 is a vapor-deposited film formed by gold or platinum vacuum vapor deposition, and has a property of not allowing the vaporized corrosive gas 3 to pass through at all or almost.
  • the bottom member 22 is made of silica-based ceramics, and the surface thereof has a surface roughness Ra that is greater than the outer surface of the resin-made tube wall 14 (PFA). Specifically, the surface roughness Ra of the bottom member 22 is 1 ⁇ m or more, and the surface roughness Ra of the tube wall 14 (PFA) is 0.1 ⁇ m or less. Therefore, the metal thin film 61 formed on the side surface 26 and the outer bottom surface 28 of the bottom member 22 has sufficient adhesion strength (peel strength).
  • the ultrasonic flowmeter 10 shown in FIG. 1 is connected to a control device (not shown) via a coaxial cable 48.
  • the control device is configured around a known microcomputer including a CPU, ROM, RAM, input / output circuit, and the like, and performs arithmetic processing of signals input / output via the coaxial cable 48.
  • ultrasonic waves are transmitted and received through the chemical liquid W1 flowing through the straight pipe portion 18 of the flow path 11 using a pair of ultrasonic transducers 16 attached to the flow meter main body 13.
  • the control device measures the propagation times when the ultrasonic waves propagate in the forward direction and the reverse direction with respect to the flow of the chemical liquid W1, based on the ultrasonic transmission signal and the ultrasonic reception signal.
  • medical solution W1 is calculated
  • the flow rate of the chemical liquid W1 is measured by converting the flow rate into a flow rate.
  • a control apparatus manages the flow volume of the chemical
  • the cylindrical member 21 and the bottom member 22 are prepared. Specifically, a pipe member made of copper is cut into a cylindrical member 21 having a predetermined length (15 mm in this embodiment). Thereafter, by performing a cutting process or the like, the U-shaped cutout portion 40 is formed at the end portion 30 of the cylindrical member 21 and two elongated slit grooves 41 are formed. In addition, after forming the notch part 40 and the elongate slit groove
  • the first electrode 33 of the ultrasonic transducer 16 is bonded and fixed to one surface which becomes the inner bottom surface 27 in the bottom member 22.
  • the ground wire 36 is solder-connected to the electrode 33a of the folded portion of the first electrode 33 on the second main surface 32 of the ultrasonic transducer 16, and the signal line 37 is connected to the second electrode 34 by soldering.
  • An ultrasonic transducer 16 is prepared in advance. Then, after applying an adhesive to either the inner bottom surface 27 of the bottom member 22 or the surface of the first electrode 33 of the ultrasonic transducer 16, the ultrasonic transducer 16 is adhered to the inner bottom surface 27 of the bottom member 22. Fix it.
  • the joining process between the tubular member 21 and the bottom member 22 is performed.
  • an adhesive is applied to one of the end surface of the tubular member 21 where the notch 40 and the slit groove 41 are not formed and the outer edge portion of the inner bottom surface 27 of the bottom member 22.
  • the member 21 and the bottom member 22 are bonded and fixed. As a result, a bottomed cylindrical vibrator holder 20 is formed.
  • the metal thin film 61 is formed on the outer surface 58 of the vibrator holder 20 by vacuum deposition of gold or platinum.
  • a gold or platinum thin film is vapor-deposited on the outer bottom surface 28 and the side surface 26 of the bottom member 22, and a region (cylinder) including the joint portion 60 between the bottom member 22 and the cylindrical member 21.
  • a thin film of gold or platinum is also deposited on a region including a part of the outer surface 62 of the member 21.
  • the metal thin film 61 is provided so that the outer surface 58 is covered to a position of about several mm on the cylindrical member 21 side with reference to the joint portion 60 between the bottom member 22 and the cylindrical member 21.
  • the conductive wire portion 36a exposed by the ground wire 36 extending from the electrode 33a of the ultrasonic transducer 16 is solder-connected to a portion sandwiched between the two slit grooves 41 on the inner surface 64 of the cylindrical member 21.
  • the ground wire 36 is solder-connected to the ground conductor 54 of the receptacle 45, and the signal line 37 extending from the second electrode 34 of the ultrasonic transducer 16 is solder-connected to the center conductor 53 of the receptacle 45.
  • the vibrator holder 20 is inserted into the housing recess 23 of the flow meter main body 13 in a state where the sheet-like buffer member 24 is disposed in close contact with the outer bottom surface 28 of the bottom member 22.
  • the vibrator holder 20 is arranged so that the U-shaped notch 40 in the cylindrical member 21 opens upward. Then, the receptacle 45 is disposed in the notch 40 and the receptacle 45 is fixed to the flowmeter main body 13 using the receptacle fixing nut 46 and the receptacle washer 47. Further, in the housing recess 23, the lid member 43 is covered from the rear of the vibrator holder 20 and the pressing lid 57 is screwed through the wave washer 56.
  • the vibrator holder 20 is pressed by the holding lid 57, and the vibrator holder 20 is pressed with the outer bottom surface 28 of the bottom member 22 pressed against the tube wall 14 side of the flow path 11 through the lid member 43 and the cylindrical member 21. 20 is mounted in the receiving recess 23.
  • the bottom member 22 and the tubular member 21 are joined to each other on the outer surface 58 of the transducer holder 20 from the outer bottom surface 28 of the bottom member 22 through the side surface 26 of the bottom member 22.
  • the metal thin film 61 is formed so as to cover a part of the outer surface 58 including the region extending over the portion 60.
  • the metal thin film 61 blocks the penetration of the gas (the vaporized gas of the chemical liquid W1) into the vibrator holder 20.
  • the electrodes 33 and 34 of the ultrasonic transducer 16 accommodated in the transducer holder 20 and the wiring (the ground wire 36 and the signal wire 37).
  • the metal thin film 61 is formed on the surface of the vibrator holder 20 (the cylindrical member 21 and the bottom member 22) made of a rigid body, not on the resin flow meter main body 13 side. Has been. Accordingly, even when the flow rate of the high-temperature chemical solution W1 is measured, the outer surface 58 of the vibrator holder 20 hardly undergoes thermal expansion like the resin surface, so that the metal thin film 61 is in close contact with the outer surface 58 of the vibrator holder 20. It is securely held in the state. As a result, even when the ultrasonic flowmeter 10 is used for a long time, the corrosion of the ultrasonic transducer 16 and the like can be avoided by the metal thin film 61.
  • the ultrasonic vibrator 16 in the vibrator holder 20, the ultrasonic vibrator 16 is fixed to the inner bottom surface 27 of the bottom member 22 and is joined to the outer edge portion of the inner bottom surface 27.
  • the outer bottom surface 28 of the bottom member 22 is pressed against the tube wall 14 by the cylindrical member 21.
  • the bottom member 22 is interposed between the ultrasonic transducer 16 and the tube wall 14 and functions as an acoustic matching layer. Specifically, the acoustic impedance of the bottom member 22 is smaller than the ultrasonic transducer 16 and larger than the tube wall 14.
  • the bottom member 22 interposing the bottom member 22 between the ultrasonic transducer 16 and the tube wall 14, the difference in acoustic impedance at the interface between the members can be reduced. Furthermore, the bottom member 22 has a thickness of ⁇ / 4 corresponding to the wavelength ⁇ of the ultrasonic wave. If it does in this way, the ultrasonic wave output from the ultrasonic transducer
  • the metal thin film 61 is made of gold or platinum, and therefore, the chemical solution W1 (chemical solution such as hydrofluoric acid or sulfuric acid) that causes corrosion flows through the flow path 11. However, sufficient corrosion resistance can be ensured for the chemical liquid W1.
  • the chemical solution W1 chemical solution such as hydrofluoric acid or sulfuric acid
  • the bottom member 22 is made of ceramics, and the surface has a surface roughness Ra larger than that of the outer surface of the resin tube wall 14. In this way, the metal thin film 61 having high adhesion strength (peel strength) and difficult to peel can be reliably formed on the side surface 26 and the outer bottom surface 28 of the bottom member 22.
  • the thickness of the metal thin film 61 is several ⁇ m, and is thinner than 1/8 (200 ⁇ m) of the wavelength ⁇ of the ultrasonic wave propagating through the metal thin film 61. Is formed.
  • the ultrasonic wave is not reflected on the surface of the metal thin film 61 and does not affect the propagation of the ultrasonic wave.
  • the material cost of the metal thin film 61 can be kept low.
  • the outer bottom surface 28 of the bottom member 22 is in close contact with the tube wall 14 via the rubber sheet-like buffer member 24, so that the ultrasonic wave is reliably transmitted. Can be propagated. Further, since the buffer member 24 has heat resistance and chemical resistance, the sheet shape is maintained without deterioration of the buffer member 24 even when used for a long period of time, so that the outer bottom surface 28 of the bottom member 22 is connected to the tube wall 14. Can be securely adhered to each other.
  • the thin film forming step is performed after the cylindrical member 21 and the bottom member 22 are bonded to form the bottomed cylindrical vibrator holder 20 in the bonding step. Accordingly, the metal thin film 61 can be formed on the outer surface 58 of the vibrator holder 20 so as to close the joint portion 60 between the tubular member 21 and the bottom member 22. Further, the vaporized gas of the chemical solution W1 can be prevented from entering the vibrator holder 20 by the metal thin film 61, and the electrodes 33 and 34 of the ultrasonic vibrator 16 accommodated in the vibrator holder 20 and the wiring 36, Corrosion of 37 etc. is avoided. Therefore, according to the present embodiment, the ultrasonic flowmeter 10 having a long product life can be manufactured efficiently and reliably.
  • two slit grooves 41 are formed on the end 30 side of the cylindrical member 21 constituting the transducer holder 20, and are sandwiched between the slit grooves 41.
  • a ground wire 36 is connected to the portion using solder.
  • the chemical solution W1 in an amount necessary for the semiconductor polishing process can be reliably supplied to the CMP apparatus. Moreover, since the chemical
  • the metal thin film 61 is formed on the outer surface 58 of the vibrator holder 20 by vacuum deposition of gold or platinum, but is not limited to this.
  • the metal thin film 61 may be formed by other methods such as CVD or electroless plating.
  • electroless plating first, electroless copper plating is performed to form a copper plating layer as a base layer, and then electroless plating of gold or platinum is performed. Even in this case, a thin film of gold or platinum having excellent corrosion resistance can be formed on the outer surface 58 of the vibrator holder 20.
  • the metal thin film 61 is formed on a part of the outer surface 58 including the joint portion 60 between the bottom member 22 and the cylindrical member 21 in the vibrator holder 20. It is not limited to. As shown in FIG. 7, a metal thin film 61 may be formed on the entire outer surface 62 of the vibrator holder 20A. Further, as shown in FIG. 8, the metal thin film 61 may be formed on the entire inner surface 65 in addition to the entire outer surface 58 of the vibrator holder 20B.
  • the metal thin film 61 When the metal thin film 61 is formed in this way, corrosion of the electrodes 33 and 34 of the ultrasonic transducer 16 and the wirings (the signal line 37 and the ground line 36) in the transducer holders 20A and 20B can be more reliably prevented. it can.
  • the cylindrical member 21 constituting the transducer holder 20 is a metal member made of copper, but is not limited to this.
  • the metal thin film 61 is formed on the entire outer surface 58 or the entire inner surface 65 as in the vibrator holders 20A and 20B shown in FIGS. 7 and 8, the metal thin film 61 ensures a shielding function against electric noise.
  • the cylindrical member 21 may be formed of ceramics (rigid body) similarly to the bottom member 22.
  • the thin film forming step is performed after the ultrasonic transducer 16 is bonded and fixed to the inner bottom surface 27 of the bottom member 22.
  • the present invention is not limited to this.
  • the ultrasonic transducer 16 may be bonded and fixed to the inner bottom surface 27 of the bottom member 22 after performing the thin film forming step.
  • the ultrasonic vibrator 16 made of lead zirconate titanate (PZT) is used, but the material for forming the ultrasonic vibrator 16 is not particularly limited. Specifically, for example, an ultrasonic vibrator made of a potassium sodium niobate-based (alkali niobate-based) piezoelectric ceramic may be used.
  • the fluororesin specifically, PFA
  • the material for forming the flow meter body 13 other resin materials may be used as long as they have excellent heat resistance and chemical resistance.
  • the material for forming the bottom member 22 that functions as an acoustic matching layer may be changed as appropriate according to the acoustic impedance of the ultrasonic transducer 16 and the acoustic impedance of the flowmeter body 13.
  • the flow meter main body 13 having the tube 12 in which the U-shaped flow path 11 is formed is used, but the present invention is not limited to this. Specifically, a flow rate having a Z-shaped flow path in which both ends of the straight pipe portion 18 are bent at right angles in opposite directions (for example, the upper side and the lower side) and a pipe formed with a flow path of other shapes.
  • a meter body may be used.
  • the ultrasonic flowmeter 10 of the said embodiment was used for the chemical
  • the ultrasonic flow meter 10 may be used in other processing apparatuses that perform processing such as cleaning of parts and generation of medicines using the chemical liquid W1.
  • the cylindrical member is a cylindrical copper pipe, and has a slightly larger inner diameter than the disk-shaped ultrasonic transducer. Ultrasonic flow meter.
  • the fluid is hydrofluoric acid or sulfuric acid as a chemical solution flowing through a chemical solution circulation line of a semiconductor manufacturing apparatus, and the liquid temperature of the chemical solution is 100 ° C or higher and 200 ° C or lower.
  • Ultrasonic flowmeter characterized by being.

Abstract

The present invention addresses the problem of providing an ultrasonic flowmeter capable of reliably preventing the corrosion of the electrodes and wiring of ultrasonic transducers and lengthening a product lifetime. An ultrasonic flowmeter (10) is provided with a resin flowmeter body (13) having a tube (12) forming a flow path (11), a pair of ultrasonic transducers (16) for transmitting and receiving ultrasound via a tube wall (14), and a pair of transducer holders (20) attached to the outside of the tube wall (14) in a state of accommodating the respective ultrasonic transducers (16). The transducer holders (20) are provided with a bottom member (22) formed into a disk shape and a tube member (21) connected to the outer edge portion of the inner bottom surface (27) of the bottom member (22). A gas-impermeable metallic thin film (61) is formed on the outer surface (58) of each transducer holder (20) so as to at least cover an area spanning the external bottom surface (28) of the bottom member (22), the side surfaces (26) of the bottom member (22), and the connection portion (60) of the bottom member (22) and tube member (21).

Description

超音波流量計及びその製造方法Ultrasonic flow meter and manufacturing method thereof
　本発明は、超音波を利用して流体の流量を測定する超音波流量計及びその製造方法に関するものである。 The present invention relates to an ultrasonic flowmeter that measures the flow rate of a fluid using ultrasonic waves, and a method for manufacturing the ultrasonic flowmeter.
　従来、半導体の製造に用いられるＣＭＰ（Ｃｈｅｍｉｃａｌ Ｍｅｃｈａｎｉｃａｌ Ｐｏｌｉｓｈｉｎｇ）装置において、フッ酸や硫酸などの薬液（流体）の流量を管理するために超音波流量計が使用されている。超音波流量計では、測定用流体としての薬液を流す配管を有し、その配管の上流側及び下流側に一対の超音波振動子が設置されている。そして、それら超音波振動子を用いて超音波を送受信し、上流側から下流側に伝搬する超音波の伝搬時間と下流側から上流側に伝搬する超音波の伝搬時間との時間差に基づいて測定用流体の流量を求めている。また、薬液を流す配管として耐薬品性に優れたフッ素樹脂が用いられている。 Conventionally, in a CMP (Chemical Mechanical Polishing) apparatus used for manufacturing a semiconductor, an ultrasonic flowmeter is used to manage the flow rate of a chemical solution (fluid) such as hydrofluoric acid or sulfuric acid. In the ultrasonic flowmeter, it has piping which flows the chemical | medical solution as a measurement fluid, and a pair of ultrasonic transducer | vibrator is installed in the upstream and downstream of the piping. Then, ultrasonic waves are transmitted and received using these ultrasonic transducers, and measured based on the time difference between the propagation time of the ultrasonic wave propagating from the upstream side to the downstream side and the propagation time of the ultrasonic wave propagating from the downstream side to the upstream side. The flow rate of industrial fluid is obtained. In addition, a fluororesin excellent in chemical resistance is used as a pipe for flowing a chemical solution.
　ＣＭＰ装置では、研磨処理の効率を高めるために高温（１００℃～２００℃）の薬液が用いられる。フッ酸や硫酸などのような特殊な薬液を高温で使用する場合、ガス化した薬液が配管のフッ素樹脂を透過し、超音波振動子側に浸透する。この薬液の浸透によって、電極等が腐食することにより超音波流量計の寿命が短くなってしまう。 In a CMP apparatus, a chemical solution at a high temperature (100 ° C. to 200 ° C.) is used to increase the efficiency of the polishing process. When a special chemical solution such as hydrofluoric acid or sulfuric acid is used at a high temperature, the gasified chemical solution permeates the fluororesin in the pipe and permeates the ultrasonic transducer side. The penetration of the chemical solution corrodes the electrode and the like, thereby shortening the life of the ultrasonic flowmeter.
　因みに、特許文献１の超音波検出器では、フッ素樹脂である四フッ化エチレン・パーフルオロアルコキシエチレン（ＰＦＡ）を用いて樹脂ホルダを有底筒状に形成し、その樹脂ホルダの底部に超音波振動子が配置されている。この超音波検出器では、樹脂ホルダの表面（内面または外面）に非ガス透過性の金属薄膜が形成されており、金属薄膜によって、液体の気化ガスが樹脂ホルダの底部を通して内部に浸透するのを阻止するようになっている。 Incidentally, in the ultrasonic detector of Patent Document 1, a resin holder is formed into a bottomed cylinder using tetrafluoroethylene / perfluoroalkoxyethylene (PFA) which is a fluororesin, and an ultrasonic wave is formed at the bottom of the resin holder. A vibrator is arranged. In this ultrasonic detector, a non-gas-permeable metal thin film is formed on the surface (inner surface or outer surface) of the resin holder, and the metal thin film prevents liquid vaporized gas from penetrating into the inside through the bottom of the resin holder. It comes to stop.
特許第４１０６４９９号公報Japanese Patent No. 4106499
　ところで、特許文献１に開示されている超音波検出器では、樹脂ホルダの形成材料として、耐薬品性に優れるフッ素樹脂（ＰＦＡ）が用いられているが、この樹脂は離型性が良好でものが付着し難いといった性質を有している。このため、樹脂ホルダの表面に対して、十分な密着強度を有する金属薄膜を形成することが困難である。特に、ＣＭＰ装置等で使用する場合のように、高温（１００℃～２００℃）の薬液の流量を測定する場合には、金属薄膜よりも樹脂が膨張するため樹脂ホルダの表面と金属薄膜との境界部分に応力が働く。さらに、熱によって樹脂が軟化する。このため、樹脂ホルダの表面から金属薄膜が剥がれ易くなったり、金属薄膜に皺がよったりするといった問題が懸念される。そして、この問題が生じる場合には、金属薄膜によって薬液の気化ガスを遮断することが困難となるため、超音波振動子の電極や配線等が腐食することにより、超音波検出器の寿命が短くなってしまう。 By the way, in the ultrasonic detector disclosed in Patent Document 1, a fluororesin (PFA) having excellent chemical resistance is used as a resin holder forming material. Has the property of being difficult to adhere. For this reason, it is difficult to form a metal thin film having sufficient adhesion strength on the surface of the resin holder. In particular, when measuring the flow rate of a chemical solution at a high temperature (100 ° C. to 200 ° C.) as used in a CMP apparatus or the like, since the resin expands more than the metal thin film, the surface of the resin holder and the metal thin film Stress acts on the boundary. Furthermore, the resin is softened by heat. For this reason, there is a concern that the metal thin film is easily peeled off from the surface of the resin holder or that the metal thin film is wrinkled. When this problem occurs, it is difficult to block the vaporized gas of the chemical solution with the metal thin film, and the life of the ultrasonic detector is shortened by corrosion of the electrodes and wiring of the ultrasonic vibrator. turn into.
　本発明は上記の課題に鑑みてなされたものであり、その目的は、超音波振動子の電極や配線の腐食を確実に防止し、製品寿命を向上することができる超音波流量計を提供することにある。また、別の目的は、製品寿命の長い超音波流量計を効率よく確実に製造することができる超音波流量計の製造方法を提供することにある。 The present invention has been made in view of the above problems, and an object of the present invention is to provide an ultrasonic flowmeter that can reliably prevent corrosion of electrodes and wiring of an ultrasonic transducer and improve product life. There is. Another object is to provide an ultrasonic flowmeter manufacturing method capable of efficiently and reliably manufacturing an ultrasonic flowmeter having a long product life.
　上記課題を解決するために、請求項１に記載の発明は、流体が流れる流路を形成する管を有する樹脂製の流量計本体と、前記流路における上流側位置及び下流側位置にて各々管壁を隔てて対向配置された位置関係にあり、前記管壁を介して超音波の送受信を行う一対の超音波振動子と、剛体からなる有底筒状の部材であり、前記超音波振動子をそれぞれ収納した状態で前記管壁の外側に装着される一対の振動子ホルダとを備え、前記一対の超音波振動子間で送受信される超音波の伝搬時間の差に基づいて、前記流体の流量を計測する超音波流量計であって、前記振動子ホルダは、側面と、前記超音波振動子が固定される内底面と、前記内底面の反対側に位置する外底面とを有する板状に形成され、前記超音波振動子と前記管壁との間に介在される音響整合層として機能する底部材と、前記底部材の前記内底面における外縁部に接合され、前記外底面を前記管壁側に押し付ける筒部材とを備えて構成され、前記振動子ホルダの外面において、前記底部材の前記外底面から前記底部材の前記側面を経て前記底部材と前記筒部材との接合部分にわたる領域を少なくとも覆うように、非ガス透過性の金属薄膜を形成したことを特徴とする超音波流量計をその要旨とする。 In order to solve the above-mentioned problem, the invention according to claim 1 is characterized in that a resin-made flowmeter body having a tube forming a flow path through which a fluid flows, and an upstream position and a downstream position in the flow path, respectively. A pair of ultrasonic transducers that are positioned opposite to each other across a tube wall and that transmit and receive ultrasonic waves through the tube wall, and a bottomed cylindrical member made of a rigid body, the ultrasonic vibration A pair of transducer holders mounted on the outside of the tube wall in a state in which each of the children is housed, and based on a difference in propagation time of ultrasonic waves transmitted and received between the pair of ultrasonic transducers, An ultrasonic flow meter for measuring the flow rate of the transducer holder, wherein the transducer holder has a side surface, an inner bottom surface to which the ultrasonic transducer is fixed, and an outer bottom surface located on the opposite side of the inner bottom surface. Formed between the ultrasonic transducer and the tube wall A bottom member that functions as an acoustic matching layer, and a cylindrical member that is joined to an outer edge portion of the inner bottom surface of the bottom member and presses the outer bottom surface against the tube wall side, and the outer surface of the vibrator holder The non-gas permeable metal thin film is formed so as to cover at least a region extending from the outer bottom surface of the bottom member through the side surface of the bottom member to the joint portion of the bottom member and the cylindrical member. The gist of the ultrasonic flowmeter is as follows.
　従って、請求項１に記載の発明によると、流路が形成された管を有する樹脂製の流量計本体において、超音波振動子をそれぞれ収納した一対の振動子ホルダが管壁の外側に装着される。各振動子ホルダに収納されている一対の超音波振動子は、流路における上流側位置及び下流側位置にて各々管壁を隔てて対向配置された位置関係にある。このため、一対の超音波振動子間で超音波を送受信すると、流路を流れる流体の速度に応じて超音波の伝搬時間に差が生じる。従って、その伝搬時間の差に基づいて、流体の速度を求めることができ、さらにその流体の速度に基づいて、流体の流量を計測することができる。本発明の超音波流量計において、流量計本体における管内の流路に、腐食をもたらす流体（例えば、硫酸やフッ酸等の薬液）を流す場合には、耐薬品性に優れた樹脂（例えば、フッ素樹脂）を用いて流量計本体を形成したとしても、流体の濃度や温度が高くなると、液体の気化ガスが流路の管壁（樹脂部分）に浸透してしまうことがある。この対策として、本発明では、振動子ホルダの外面において、底部材の外底面から底部材の側面を経て底部材と筒部材との接合部分にわたる領域を少なくとも覆うように、金属薄膜が形成される。そして、その金属薄膜によって振動子ホルダ内へのガスの浸透が遮断される。この結果、振動子ホルダ内に収容された超音波振動子の電極や配線等の腐食を回避することができる。また、本発明の超音波流量計において、金属薄膜は、樹脂製の流量計本体側ではなく、剛体からなる振動子ホルダ（底部材及び筒部材）の表面に形成されている。従って、高温の流体の流量を計測する場合であっても、振動子ホルダの外面は樹脂表面のような熱膨張が生じ難いため、その振動子ホルダの外面に金属薄膜が密着した状態で確実に保持される。この結果、超音波流量計を長期間使用した場合でも、金属薄膜によって超音波振動子等の腐食を回避することができる。さらに、振動子ホルダにおいて、底部材の内底面に超音波振動子が固定されるとともに、その内底面における外縁部に接合された筒部材によって底部材の外底面が管壁側に押し付けられている。この底部材は、超音波振動子と管壁との間に介在され、音響整合層として機能するため、超音波振動子から出力された超音波を管壁を介して流体に効率よく伝搬させることができ、流体の流量を正確に測定することができる。 Therefore, according to the first aspect of the present invention, in the resin flowmeter main body having the tube in which the flow path is formed, the pair of transducer holders each accommodating the ultrasonic transducer are mounted on the outside of the tube wall. The The pair of ultrasonic transducers housed in each transducer holder is in a positional relationship in which the ultrasonic transducers are opposed to each other across the tube wall at the upstream position and the downstream position in the flow path. For this reason, when ultrasonic waves are transmitted and received between a pair of ultrasonic transducers, a difference occurs in the propagation time of the ultrasonic waves according to the velocity of the fluid flowing through the flow path. Therefore, the velocity of the fluid can be obtained based on the difference in propagation time, and the flow rate of the fluid can be measured based on the velocity of the fluid. In the ultrasonic flowmeter of the present invention, when a fluid that causes corrosion (for example, a chemical solution such as sulfuric acid or hydrofluoric acid) is allowed to flow through the flow path in the pipe of the flowmeter body, a resin having excellent chemical resistance (for example, Even if the flowmeter body is formed using a fluororesin), the liquid vaporized gas may permeate the tube wall (resin portion) of the flow path when the concentration or temperature of the fluid increases. As a countermeasure, in the present invention, a metal thin film is formed on the outer surface of the vibrator holder so as to cover at least a region extending from the outer bottom surface of the bottom member through the side surface of the bottom member to the joint portion between the bottom member and the cylindrical member. . The metal thin film blocks gas penetration into the vibrator holder. As a result, it is possible to avoid corrosion of the electrodes and wiring of the ultrasonic vibrator housed in the vibrator holder. In the ultrasonic flowmeter of the present invention, the metal thin film is formed not on the resin flowmeter main body side but on the surface of a rigid vibrator holder (bottom member and cylindrical member). Therefore, even when measuring the flow rate of a high-temperature fluid, the outer surface of the vibrator holder is unlikely to undergo thermal expansion like the resin surface, so it is ensured that the metal thin film is in close contact with the outer face of the vibrator holder. Retained. As a result, even when the ultrasonic flowmeter is used for a long period of time, corrosion of the ultrasonic vibrator or the like can be avoided by the metal thin film. Further, in the vibrator holder, the ultrasonic vibrator is fixed to the inner bottom surface of the bottom member, and the outer bottom surface of the bottom member is pressed against the tube wall side by the cylindrical member joined to the outer edge portion of the inner bottom surface. . Since this bottom member is interposed between the ultrasonic transducer and the tube wall and functions as an acoustic matching layer, the ultrasonic wave output from the ultrasonic transducer can be efficiently propagated to the fluid through the tube wall. And the fluid flow rate can be measured accurately.
　請求項２に記載の発明は、請求項１において、前記振動子ホルダにおける前記外面の全体に、前記金属薄膜を形成したことをその要旨とする。 The gist of the invention described in claim 2 is that, in claim 1, the metal thin film is formed on the entire outer surface of the vibrator holder.
　従って、請求項２に記載の発明によると、振動子ホルダにおける外面の全体に、金属薄膜が形成されることにより、振動子ホルダ内の超音波振動子の電極や配線等の腐食を確実に防止することができる。またこの場合、金属薄膜をシールド層として機能させることができ、超音波振動子の出力信号に電気ノイズが重畳することを防止することができる。 Therefore, according to the second aspect of the present invention, the metal thin film is formed on the entire outer surface of the vibrator holder, thereby reliably preventing corrosion of the electrodes and wiring of the ultrasonic vibrator in the vibrator holder. can do. In this case, the metal thin film can function as a shield layer, and electrical noise can be prevented from being superimposed on the output signal of the ultrasonic transducer.
　請求項３に記載の発明は、請求項１において、前記振動子ホルダにおける前記外面の全体及び内面の全体に、前記金属薄膜を形成したことをその要旨とする。 The gist of the invention described in claim 3 is that, in claim 1, the metal thin film is formed on the entire outer surface and the entire inner surface of the vibrator holder.
　従って、請求項３に記載の発明によると、振動子ホルダにおける外面の全体及び内面の全体に、２重に金属薄膜が形成されるため、振動子ホルダ内の超音波振動子の電極や配線等の腐食をより確実に防止することができる。またこの場合、２重のシールド構造によって超音波振動子や配線等が保護されるため、電気ノイズに対するシールド効果を高めることができる。 Therefore, according to the third aspect of the present invention, since the metal thin film is formed twice on the entire outer surface and the entire inner surface of the vibrator holder, the electrodes and wiring of the ultrasonic vibrator in the vibrator holder, etc. Corrosion can be prevented more reliably. Further, in this case, since the ultrasonic vibrator, the wiring and the like are protected by the double shield structure, the shielding effect against electric noise can be enhanced.
　請求項４に記載の発明は、請求項１乃至３のいずれか１項において、前記金属薄膜は、金または白金からなることをその要旨とする。 The gist of the invention of claim 4 is that, in any one of claims 1 to 3, the metal thin film is made of gold or platinum.
　従って、請求項４に記載の発明によると、金属薄膜を金または白金で形成することにより、腐食をもたらす流体（例えばフッ酸や硫酸などの薬液）を流路に流す場合であっても、その流体に対して十分な耐腐食性を確保することができる。 Therefore, according to the invention described in claim 4, even when a fluid that causes corrosion (for example, a chemical solution such as hydrofluoric acid or sulfuric acid) is caused to flow through the flow path by forming the metal thin film with gold or platinum, Sufficient corrosion resistance can be ensured for the fluid.
　請求項５に記載の発明は、請求項１乃至４のいずれか１項において、前記底部材は、音響インピーダンスが前記超音波振動子よりも小さく、かつ前記管壁よりも大きいセラミックスであることをその要旨とする。 According to a fifth aspect of the present invention, in any one of the first to fourth aspects, the bottom member is a ceramic having an acoustic impedance smaller than that of the ultrasonic transducer and larger than that of the tube wall. The gist.
　従って、請求項５に記載の発明によれば、超音波振動子と管壁との間に底部材を介在させることにより、各部材間の界面における音響インピーダンスの差を小さくすることができる。このため、流路を流れる液体に超音波を効率よく確実に伝搬させることができる。 Therefore, according to the fifth aspect of the present invention, the difference in acoustic impedance at the interface between each member can be reduced by interposing the bottom member between the ultrasonic transducer and the tube wall. For this reason, an ultrasonic wave can be efficiently and reliably propagated to the liquid flowing through the flow path.
　請求項６に記載の発明は、請求項１乃至５のいずれか１項において、前記流量計本体の流路は、ストレート状に延設された直管部を有するとともにその直管部の両端が直角に曲がった形状の管路であり、前記直管部における上流側及び下流側の各端部に前記一対の超音波振動子が設けられていることをその要旨とする。 A sixth aspect of the present invention is the flowmeter of the flowmeter main body according to any one of the first to fifth aspects, wherein the flowmeter body has a straight pipe portion extending straight and both ends of the straight pipe portion are The gist is that the pipe is bent at a right angle, and the pair of ultrasonic transducers is provided at each of the upstream and downstream ends of the straight pipe portion.
　従って、請求項６に記載の発明によれば、一対の超音波振動子を用いて、直管部を流れる流体を介して超音波が送受信され、液体の流れに対して正方向及び逆方向に超音波が伝搬する際の伝搬時間がそれぞれ測定される。そして、それら伝搬時間の差から液体の流速を求めることができ、さらにその流速を流量に変換することにより、液体の流量を測定することができる。 Therefore, according to the sixth aspect of the present invention, using a pair of ultrasonic transducers, ultrasonic waves are transmitted and received through the fluid flowing through the straight pipe portion, and in the forward and reverse directions with respect to the liquid flow. The propagation time when the ultrasonic wave propagates is measured. The flow rate of the liquid can be obtained from the difference between the propagation times, and the flow rate of the liquid can be measured by converting the flow rate into a flow rate.
　請求項７に記載の発明は、請求項１乃至６のいずれか１項において、前記底部材の表面は、前記管壁の外面よりも表面粗さの値が大きいことをその要旨とする。 The gist of the invention according to claim 7 is that, in any one of claims 1 to 6, the surface of the bottom member has a surface roughness value larger than that of the outer surface of the tube wall.
　従って、請求項７に記載の発明によれば、底部材の表面（側面及び外底面）に、密着強度（剥離強度）が高く、剥離し難い金属薄膜を確実に形成することができる。 Therefore, according to the seventh aspect of the present invention, a metal thin film having high adhesion strength (peel strength) and difficult to peel can be reliably formed on the surface (side surface and outer bottom surface) of the bottom member.
　請求項８に記載の発明は、請求項１乃至７のいずれか１項において、前記底部材は、前記超音波の波長λに応じたλ／４の厚みを有することをその要旨とする。 The gist of the invention according to claim 8 is that, in any one of claims 1 to 7, the bottom member has a thickness of λ / 4 corresponding to the wavelength λ of the ultrasonic wave.
　従って、請求項８に記載の発明によれば、底部材を音響整合層として機能させることができ、管壁を介して液体に超音波を効率よく伝搬させることができる。 Therefore, according to the invention described in claim 8, the bottom member can function as an acoustic matching layer, and ultrasonic waves can be efficiently propagated to the liquid through the tube wall.
　請求項９に記載の発明は、請求項１乃至８のいずれか１項において、前記金属薄膜は、前記超音波の波長λの１／８の厚さよりも薄く形成されることをその要旨とする。 The gist of a ninth aspect of the present invention is that, in any one of the first to eighth aspects, the metal thin film is formed to be thinner than １ ／ of the wavelength λ of the ultrasonic wave. .
　従って、請求項９に記載の発明のように、金属薄膜を薄く形成すると、金属薄膜の表面において超音波が反射することがなく、超音波の伝搬に影響することがない。さらに、金属薄膜の材料費を低く抑えることができる。 Therefore, as in the invention described in claim 9, when the metal thin film is formed thin, the ultrasonic wave is not reflected on the surface of the metal thin film, and the propagation of the ultrasonic wave is not affected. Furthermore, the material cost of the metal thin film can be kept low.
　請求項１０に記載の発明は、請求項１乃至９のいずれか１項において、前記振動子ホルダにおいて前記金属薄膜を形成した前記外底面は、耐熱性及び耐薬品性を有するゴム製のシート状の緩衝部材を介して前記管壁に密着されることをその要旨とする。 A tenth aspect of the present invention is the rubber sheet according to any one of the first to ninth aspects, wherein the outer bottom surface on which the metal thin film is formed in the vibrator holder has a heat resistance and a chemical resistance. The gist is to be in close contact with the tube wall through the buffer member.
　従って、請求項１０に記載の発明によれば、底部材の外底面がシート状の緩衝部材を介して管壁に密着されるので、超音波を確実に伝搬させることができる。ここで、底部材の外底面と管壁との間にグリス等を介在させる場合、高温で長期間使用すると、グリスはその形状を保持することができないため、それら部材間に隙間が生じて密着性が低下することがある。これに対して、本発明では、耐熱性及び耐薬品性を有するシート状の緩衝部材を用いているので、長期間使用しても緩衝部材が劣化することなく、底部材の外底面を管壁に確実に密着させることができる。 Therefore, according to the invention described in claim 10, since the outer bottom surface of the bottom member is brought into close contact with the tube wall via the sheet-like buffer member, the ultrasonic wave can be reliably propagated. Here, when grease or the like is interposed between the outer bottom surface of the bottom member and the tube wall, the grease cannot maintain its shape when used at a high temperature for a long time. May decrease. On the other hand, in the present invention, since the sheet-like buffer member having heat resistance and chemical resistance is used, the outer bottom surface of the bottom member is not affected by deterioration of the buffer member even when used for a long period of time. Can be securely adhered to each other.
　請求項１１に記載の発明は、請求項１乃至１０のいずれか１項に記載の超音波流量計を製造する方法であって、前記筒部材と前記底部材とを接着剤を用いて接合し、前記有底筒状の振動子ホルダを形成する接合工程と、前記接合工程の後、前記振動子ホルダの外面に、非ガス透過性の金属薄膜を形成する薄膜形成工程とを含むことを特徴とする超音波流量計の製造方法をその要旨とする。 The invention described in claim 11 is a method of manufacturing the ultrasonic flowmeter according to any one of claims 1 to 10, wherein the cylindrical member and the bottom member are joined using an adhesive. A bonding step of forming the bottomed cylindrical vibrator holder; and a thin film forming step of forming a non-gas permeable metal thin film on the outer surface of the vibrator holder after the bonding step. The gist of the manufacturing method of the ultrasonic flowmeter is as follows.
　従って、請求項１１に記載の発明によれば、接合工程において、筒部材と底部材とを接合して有底筒状の振動子ホルダを形成した後に薄膜形成工程が実施されるので、振動子ホルダの外面において、筒部材と底部材との接合部分を塞ぐように金属薄膜を確実に形成することができる。この結果、金属薄膜によって振動子ホルダ内に液体の気化ガスが入り込むことを防止することができ、振動子ホルダ内に収容された超音波振動子の電極や配線等の腐食が回避される。従って、本発明によると、製品寿命の長い超音波流量計を効率よく確実に製造することができる。 Therefore, according to the invention described in claim 11, in the joining step, the thin film forming step is performed after the tubular member and the bottom member are joined to form the bottomed tubular vibrator holder. On the outer surface of the holder, the metal thin film can be reliably formed so as to block the joint portion between the tubular member and the bottom member. As a result, liquid vaporized gas can be prevented from entering the vibrator holder by the metal thin film, and corrosion of electrodes and wiring of the ultrasonic vibrator housed in the vibrator holder can be avoided. Therefore, according to the present invention, an ultrasonic flowmeter having a long product life can be manufactured efficiently and reliably.
　以上詳述したように、請求項１～１０に記載の発明によると、超音波振動子の電極や配線の腐食を確実に防止し、超音波流量計の製品寿命を向上することができる。また、請求項１１に記載の発明によると、製品寿命の長い超音波流量計を効率よく確実に製造することができる。 As described in detail above, according to the inventions of claims 1 to 10, corrosion of the electrodes and wiring of the ultrasonic vibrator can be surely prevented, and the product life of the ultrasonic flowmeter can be improved. In addition, according to the invention described in claim 11, an ultrasonic flowmeter having a long product life can be manufactured efficiently and reliably.
一実施の形態の超音波流量計を示す断面図。Sectional drawing which shows the ultrasonic flowmeter of one embodiment. 一実施の形態の超音波流量計の要部を示す拡大断面図。The expanded sectional view showing the important section of the ultrasonic flowmeter of one embodiment. 一実施の形態の超音波振動子を示す断面図。Sectional drawing which shows the ultrasonic transducer | vibrator of one Embodiment. 一実施の形態の超音波振動子を示す斜視図。The perspective view which shows the ultrasonic transducer | vibrator of one Embodiment. 一実施の形態の振動子ホルダを示す分解斜視図。The disassembled perspective view which shows the vibrator | oscillator holder of one Embodiment. 一実施の形態の振動子ホルダを示す断面図。Sectional drawing which shows the vibrator | oscillator holder of one embodiment. 別の実施の形態の振動子ホルダを示す断面図。Sectional drawing which shows the vibrator holder of another embodiment. 別の実施の形態の振動子ホルダを示す断面図。Sectional drawing which shows the vibrator holder of another embodiment.
　以下、本発明を超音波流量計に具体化した一実施の形態を図面に基づき詳細に説明する。 Hereinafter, an embodiment in which the present invention is embodied in an ultrasonic flowmeter will be described in detail with reference to the drawings.
　図１に示される超音波流量計１０は、ＣＭＰ（Ｃｈｅｍｉｃａｌ Ｍｅｃｈａｎｉｃａｌ Ｐｏｌｉｓｈｉｎｇ）装置の薬液供給ラインの途中に設けられ、ＣＭＰ装置に供給される薬液Ｗ１（流体）の流量を測定する。本実施の形態において、ＣＭＰ装置に供給される薬液Ｗ１はフッ酸または硫酸であり、薬液Ｗ１の液温は１００℃以上２００℃以下の温度である。 An ultrasonic flow meter 10 shown in FIG. 1 is provided in the middle of a chemical solution supply line of a CMP (Chemical Mechanical Polishing) device, and measures the flow rate of the chemical solution W1 (fluid) supplied to the CMP device. In the present embodiment, the chemical liquid W1 supplied to the CMP apparatus is hydrofluoric acid or sulfuric acid, and the liquid temperature of the chemical liquid W1 is a temperature of 100 ° C. or higher and 200 ° C. or lower.
　超音波流量計１０は、薬液Ｗ１が流れる流路１１を形成する管１２を有する樹脂製の流量計本体１３と、流路１１における上流側位置及び下流側位置にて各々管壁１４を隔てて対向配置された位置関係にある一対の超音波振動子１６とを備える。流量計本体１３の流路１１は、薬液循環ラインに接続される液体圧送用の管路であり、流れの方向に沿ってコ字状に形成されている。つまり、流量計本体１３の流路は、ストレート状に延設された直管部１８を有するとともにその直管部１８の両端が同一方向（図１では上側）に直角に曲がった形状の管路である。この流量計本体１３において、流路１１の直管部１８における上流側及び下流側の各端部に一対の超音波振動子１６が設けられている。流量計本体１３は、耐熱性及び耐薬品性に優れるフッ素樹脂（具体的には、ＰＦＡ）を用いて形成されており、直管部１８の長さは１０ｃｍ程度である。流量計本体１３の管１２内に形成される流路１１の断面形状は円形であり、その口径は６ｍｍ程度である。 The ultrasonic flowmeter 10 has a resin-made flowmeter body 13 having a pipe 12 forming a flow path 11 through which a chemical solution W1 flows, and a pipe wall 14 at an upstream position and a downstream position in the flow path 11. And a pair of ultrasonic transducers 16 in a positional relationship facing each other. The flow path 11 of the flow meter body 13 is a liquid pressure-feeding pipe connected to the chemical liquid circulation line, and is formed in a U shape along the flow direction. That is, the flow channel of the flowmeter body 13 has a straight pipe portion 18 extending straight and both ends of the straight pipe portion 18 are bent at right angles in the same direction (upper side in FIG. 1). It is. In the flow meter body 13, a pair of ultrasonic transducers 16 are provided at the upstream and downstream ends of the straight pipe portion 18 of the flow path 11. The flow meter body 13 is formed using a fluororesin (specifically, PFA) having excellent heat resistance and chemical resistance, and the length of the straight pipe portion 18 is about 10 cm. The cross-sectional shape of the flow path 11 formed in the pipe 12 of the flow meter main body 13 is circular, and the aperture is about 6 mm.
　図１及び図２に示されるように、本実施の形態の超音波流量計１０は、剛体からなる有底筒状の部材であり、超音波振動子１６をそれぞれ収納した状態で流量計本体１３に装着される一対の振動子ホルダ２０をさらに備えている。より詳しくは、本実施の形態の振動子ホルダ２０は、円筒状の筒部材２１と、円板状の底部材２２とによって有底円筒状に形成されている（図５参照）。また、流量計本体１３において、直管部１８の両端に位置する管壁１４の外側には、収容凹部２３がそれぞれ形成されている。そして、各収容凹部２３内において、振動子ホルダ２０の底部材２２を直管部１８（管壁１４）側に向け、かつその底部材２２を緩衝部材２４を介して流路１１の管壁１４に当接させた状態で振動子ホルダ２０が収容されている。 As shown in FIGS. 1 and 2, the ultrasonic flowmeter 10 of the present embodiment is a bottomed cylindrical member made of a rigid body, and the flowmeter main body 13 in a state in which the ultrasonic transducer 16 is housed. And a pair of vibrator holders 20 to be mounted on. More specifically, the vibrator holder 20 of the present embodiment is formed into a bottomed cylindrical shape by a cylindrical tube member 21 and a disk-shaped bottom member 22 (see FIG. 5). Further, in the flow meter main body 13, receiving recesses 23 are formed on the outer sides of the tube walls 14 positioned at both ends of the straight pipe portion 18. In each housing recess 23, the bottom member 22 of the vibrator holder 20 is directed to the straight pipe portion 18 (tube wall 14) side, and the bottom member 22 is passed through the buffer member 24 to the tube wall 14 of the flow path 11. The vibrator holder 20 is housed in a state where the vibrator holder 20 is in contact therewith.
　緩衝部材２４は、耐熱性及び耐薬品性に優れた材料（シリコーンゴムやフッ素ゴムなど）を用いて形成されたゴム製のシート状の部材である。なお、緩衝部材２４は、超音波の伝搬に影響がない厚さ（例えば、２００μｍ程度の厚さ）であり、底部材２２よりも薄く形成されている。また、シート状の緩衝部材２４に代えてグリス（例えばシリコーングリス）を塗布し、振動子ホルダ２０の底部材２２と管壁１４との密着性を保つように構成してもよい。 The buffer member 24 is a rubber sheet-like member formed using a material having excellent heat resistance and chemical resistance (such as silicone rubber or fluoro rubber). The buffer member 24 has a thickness that does not affect the propagation of ultrasonic waves (for example, a thickness of about 200 μm), and is formed thinner than the bottom member 22. Further, grease (for example, silicone grease) may be applied instead of the sheet-like buffer member 24 so that the adhesion between the bottom member 22 of the vibrator holder 20 and the tube wall 14 is maintained.
　振動子ホルダ２０を構成する筒部材２１は、シールド部材として機能する銅パイプからなり、外径が１２．５ｍｍ程度、長さが１５ｍｍ程度である。また、筒部材２１の内径は超音波振動子１６の直径よりも若干大きい。この筒部材２１の内側に超音波振動子１６を収容した状態では、筒部材２１の内面と超音波振動子１６の側面との間に隙間が形成されている。 The cylindrical member 21 constituting the vibrator holder 20 is made of a copper pipe functioning as a shield member, and has an outer diameter of about 12.5 mm and a length of about 15 mm. Further, the inner diameter of the cylindrical member 21 is slightly larger than the diameter of the ultrasonic transducer 16. In a state where the ultrasonic transducer 16 is accommodated inside the cylindrical member 21, a gap is formed between the inner surface of the cylindrical member 21 and the side surface of the ultrasonic transducer 16.
　振動子ホルダ２０を構成する底部材２２は、シリカ（ＳｉＯ２）を含んで構成されたシリカ系のセラミックスであり、側面２６と、超音波振動子１６が固定される内底面２７と、内底面２７の反対側に位置する外底面２８とを有する円板状に形成されている（図５等参照）。底部材２２は、超音波振動子１６よりも大きい直径（筒部材２１と等しい１２．５ｍｍ程度の直径）を有している。そして、底部材２２の内底面２７において、超音波振動子１６の固定部よりも外側となる外縁部に筒部材２１の端部２９が接着剤を用いて接合されている。 The bottom member 22 constituting the vibrator holder 20 is a silica-based ceramics containing silica (SiO 2 ), and includes a side face 26, an inner bottom face 27 to which the ultrasonic vibrator 16 is fixed, and an inner bottom face. 27 is formed in a disk shape having an outer bottom surface 28 located on the opposite side of 27 (see FIG. 5 and the like). The bottom member 22 has a larger diameter than the ultrasonic transducer 16 (a diameter of about 12.5 mm, which is equal to the cylindrical member 21). And in the inner bottom face 27 of the bottom member 22, the edge part 29 of the cylinder member 21 is joined to the outer edge part outside the fixing part of the ultrasonic transducer | vibrator 16 using the adhesive agent.
　本実施の形態の超音波振動子１６は、例えば、チタン酸ジルコン酸鉛（ＰＺＴ）からなり、直径１０ｍｍ、厚さ１．０ｍｍ程度のサイズを有する円板状に形成されている。図３及び図４に示されるように、超音波振動子１６は、第１主面３１とその裏面側に設けられた第２主面３２とを有している。超音波振動子１６の各主面３１，３２には、折り返し電極３３ａを有する一対の電極３３，３４が設けられている。 The ultrasonic transducer 16 of the present embodiment is made of, for example, lead zirconate titanate (PZT), and is formed in a disk shape having a diameter of about 10 mm and a thickness of about 1.0 mm. As shown in FIGS. 3 and 4, the ultrasonic transducer 16 has a first main surface 31 and a second main surface 32 provided on the back side thereof. A pair of electrodes 33 and 34 each having a folded electrode 33 a is provided on each of the main surfaces 31 and 32 of the ultrasonic transducer 16.
　より詳しくは、超音波振動子１６において、第１主面３１側には第１電極３３（接地電極）が設けられており、その第１電極３３の表面が振動子ホルダ２０の底部材２２の内底面２７に接着固定されている（図５参照）。また、超音波振動子１６において、第２主面３２側には、第１主面３１側から折り返された第１電極３３の一部３３ａと第２電極３４（作動電極）とが設けられている。各電極３３，３４は銀を用いて形成されている。図５に示されるように、超音波振動子１６の第２主面３２側において電極３３ａにグランド線３６が接続されるとともに、第２電極３４に信号線３７が接続される。なお、第２主面３２において、電極３３ａと電極３４とは所定の間隔をあけて設けられており、それら電極間が絶縁されている（図３及び図４参照）。 More specifically, in the ultrasonic transducer 16, a first electrode 33 (ground electrode) is provided on the first main surface 31 side, and the surface of the first electrode 33 is the bottom member 22 of the transducer holder 20. It is bonded and fixed to the inner bottom surface 27 (see FIG. 5). In the ultrasonic transducer 16, a part 33 a of the first electrode 33 and a second electrode 34 (working electrode) folded from the first main surface 31 side are provided on the second main surface 32 side. Yes. Each electrode 33, 34 is formed using silver. As shown in FIG. 5, the ground line 36 is connected to the electrode 33 a on the second main surface 32 side of the ultrasonic transducer 16, and the signal line 37 is connected to the second electrode 34. In addition, in the 2nd main surface 32, the electrode 33a and the electrode 34 are provided at predetermined intervals, and these electrodes are insulated (refer FIG.3 and FIG.4).
　図２に示されるように、超音波振動子１６において、第１主面３１全体が振動子ホルダ２０における底部材２２に接着されており、その第１主面３１が、超音波を放射するための音響放射面として機能する。また、流路１１の管壁１４と超音波振動子１６との間に介在され、超音波振動子１６の音響放射面（第１主面３１）に接着される底部材２２が音響整合層として機能する。つまり、底部材２２は、音響インピーダンスが超音波振動子１６よりも小さく、かつ管壁１４よりも大きい部材であり、超音波を効率よく伝搬する。具体的には、超音波振動子１６（ＰＺＴ）の音響インピーダンスは、３０．０×１０６Ｎ・ｓ／ｍ３であり、底部材２２（音響整合層）の音響インピーダンスは、１２．５×１０６Ｎ・ｓ／ｍ３であり、管壁１４（ＰＦＡ）の音響インピーダンスは、２．６×１０６Ｎ・ｓ／ｍ３である。 As shown in FIG. 2, in the ultrasonic transducer 16, the entire first main surface 31 is bonded to the bottom member 22 of the transducer holder 20, and the first main surface 31 emits ultrasonic waves. It functions as an acoustic radiation surface. The bottom member 22 interposed between the tube wall 14 of the flow path 11 and the ultrasonic transducer 16 and bonded to the acoustic radiation surface (first main surface 31) of the ultrasonic transducer 16 serves as an acoustic matching layer. Function. That is, the bottom member 22 is a member having an acoustic impedance smaller than that of the ultrasonic transducer 16 and larger than that of the tube wall 14 and efficiently propagates ultrasonic waves. Specifically, the acoustic impedance of the ultrasonic transducer 16 (PZT) is 30.0 × 10 6 N · s / m 3 , and the acoustic impedance of the bottom member 22 (acoustic matching layer) is 12.5 ×. 10 6 N · s / m 3 and the acoustic impedance of the tube wall 14 (PFA) is 2.6 × 10 6 N · s / m 3 .
　また、本実施の形態では、超音波振動子１６の共振周波数をｆとし、底部材２２中の音速をｖとしたときに、底部材２２の厚みｔ（＝０．６２５ｍｍ）が、ｔ＝｛ｖ／(４ｆ)｝±１０％の関係を満たすように底部材２２を形成している。つまり、超音波の波長λ（＝ｖ／ｆ）の１／４倍に対応する厚みｔで底部材２２が形成されている。なお、超音波振動子１６の共振周波数ｆは２ＭＨｚであり、底部材２２中の音速ｖは５０００ｍ／ｓ程度である。また、超音波振動子１６と底部材２２との間に介在する接着層（図示略）は、超音波の伝搬に影響がない厚さ（数十μｍ程度の厚さ）であり、底部材２２よりも薄く形成されている。 In the present embodiment, when the resonance frequency of the ultrasonic transducer 16 is f and the sound velocity in the bottom member 22 is v, the thickness t (= 0.625 mm) of the bottom member 22 is t = { The bottom member 22 is formed so as to satisfy the relationship of v / (4f)} ± 10%. That is, the bottom member 22 is formed with a thickness t corresponding to ¼ times the wavelength λ (= v / f) of the ultrasonic wave. Note that the resonance frequency f of the ultrasonic transducer 16 is 2 MHz, and the sound velocity v in the bottom member 22 is about 5000 m / s. The adhesive layer (not shown) interposed between the ultrasonic transducer 16 and the bottom member 22 has a thickness (thickness of about several tens of μm) that does not affect the propagation of the ultrasonic waves. It is formed thinner than.
　図５に示されるように、振動子ホルダ２０を構成する筒部材２１において、底部材２２が接合される一方（図では下方）の端部２９とは反対側に位置する他方（図では上方）の端部３０側には、その端部３０から一方の端部２９側に延びるようにＵ字状の切り欠き部４０が形成されている。さらに、筒部材２１においてＵ字状の切り欠き部４０と対向する位置には、２本の細長いスリット溝４１が形成されている。そして、筒部材２１の内面において、２本のスリット溝４１にて挟まれた部位に、グランド線３６がはんだ付けされるようになっている。なお、本実施の形態では、超音波振動子１６の電極３３ａに接続されたグランド線３６の途中にて、その被覆の一部が除去されることで導線部分３６ａが露出しており、その露出した導線部分３６ａが筒部材２１にはんだ接続されている。 As shown in FIG. 5, in the cylindrical member 21 constituting the vibrator holder 20, the bottom member 22 is joined to the other side (lower side in the drawing) and the other side (upward side in the drawing) located on the opposite side. A U-shaped cutout portion 40 is formed on the end portion 30 side so as to extend from the end portion 30 to the one end portion 29 side. Further, two elongated slit grooves 41 are formed at positions facing the U-shaped notch 40 in the cylindrical member 21. A ground wire 36 is soldered to a portion sandwiched between the two slit grooves 41 on the inner surface of the cylindrical member 21. In the present embodiment, the conductor portion 36a is exposed by removing a part of the coating in the middle of the ground wire 36 connected to the electrode 33a of the ultrasonic transducer 16, and the exposure is performed. The conducting wire portion 36a is solder-connected to the cylindrical member 21.
　図２に示されるように、筒部材２１において、切り欠き部４０やスリット溝４１が形成される端部３０には、銅からなる円板状の蓋部材４３がその端部３０の開口を塞ぐように配置されている。このように、筒部材２１、底部材２２及び蓋部材４３の各部材が超音波振動子１６を包囲するように配置される。 As shown in FIG. 2, in the cylindrical member 21, a disk-shaped lid member 43 made of copper closes the opening of the end 30 at the end 30 where the notch 40 and the slit groove 41 are formed. Are arranged as follows. In this way, the cylindrical member 21, the bottom member 22, and the lid member 43 are disposed so as to surround the ultrasonic transducer 16.
　流量計本体１３の収容凹部２３に振動子ホルダ２０を装着した場合、筒部材２１の切り欠き部４０が上方に位置し、切り欠き部４０よって上方が開口した形態となる。また、振動子ホルダ２０において、筒部材２１の切り欠き部４０には、同軸ケーブル用のレセプタクル４５が配置される。本実施の形態のレセプタクル４５は、ＳＭＢ仕様のレセプタクルであり、レセプタクル固定ナット４６及びレセプタクルワッシャ４７等を用いて流量計本体１３に固定されている。そして、そのレセプタクル４５には、同軸ケーブル４８の先端に取り付けられた同軸プラグ４９が結合されている。なお、同軸プラグ４９は、レセプタクル４５に結合可能なプラグ型のＳＭＢ同軸コネクタである。さらに、流量計本体１３において、レセプタクル４５と同軸プラグ４９との結合部を覆うように、有底二段円筒状のカバー部材５１が装着されている。カバー部材５１は、流量計本体１３と同様に、耐熱性及び耐薬品性に優れるフッ素樹脂（例えば、ＰＦＡ）を用いて形成されている。 When the vibrator holder 20 is mounted in the housing recess 23 of the flow meter main body 13, the cutout portion 40 of the cylindrical member 21 is positioned upward, and the upper portion is opened by the cutout portion 40. In the vibrator holder 20, a coaxial cable receptacle 45 is disposed in the notch 40 of the cylindrical member 21. The receptacle 45 according to the present embodiment is an SMB specification receptacle, and is fixed to the flow meter main body 13 using a receptacle fixing nut 46, a receptacle washer 47, and the like. A coaxial plug 49 attached to the tip of the coaxial cable 48 is coupled to the receptacle 45. The coaxial plug 49 is a plug-type SMB coaxial connector that can be coupled to the receptacle 45. Further, in the flow meter main body 13, a bottomed two-stage cylindrical cover member 51 is mounted so as to cover the coupling portion between the receptacle 45 and the coaxial plug 49. The cover member 51 is formed using a fluororesin (for example, PFA) that is excellent in heat resistance and chemical resistance, similarly to the flow meter main body 13.
　また、レセプタクル４５の中心導体５３と、超音波振動子１６の第２電極３４とが信号線３７を介して接続される。一方、レセプタクル４５の接地導体５４と、筒部材２１及び超音波振動子１６の第１電極３３の一部３３ａとがグランド線３６を介して接続される。この結果、超音波振動子１６の第１電極３３（接地電極）、筒部材２１、及び蓋部材４３が同電位（グランド電位）とされる。この構成により、信号線３７は、いずれも接地された超音波振動子１６の第１電極３３、筒部材２１、蓋部材４３、及びレセプタクル４５の接地導体５４によって囲まれた空間内に配置されている。従って、信号線３７の信号、つまり超音波振動子１６の出力信号にノイズが重畳することが効果的に防止される。 Also, the central conductor 53 of the receptacle 45 and the second electrode 34 of the ultrasonic transducer 16 are connected via a signal line 37. On the other hand, the ground conductor 54 of the receptacle 45 is connected to the cylindrical member 21 and a part 33 a of the first electrode 33 of the ultrasonic transducer 16 via the ground line 36. As a result, the first electrode 33 (ground electrode), the cylindrical member 21, and the lid member 43 of the ultrasonic transducer 16 are set to the same potential (ground potential). With this configuration, the signal line 37 is disposed in a space surrounded by the grounded conductor 54 of the first electrode 33, the cylindrical member 21, the lid member 43, and the receptacle 45, all of which are grounded. Yes. Therefore, it is possible to effectively prevent noise from being superimposed on the signal of the signal line 37, that is, the output signal of the ultrasonic transducer 16.
　さらに、振動子ホルダ２０の蓋部材４３の外側（図２では右側）には、波ワッシャ５６を介して押さえ蓋５７が配設されている。押さえ蓋５７は、流量計本体１３の収容凹部２３に螺着されており、波ワッシャ５６を介して振動子ホルダ２０を押圧する。この結果、振動子ホルダ２０において、筒部材２１を介して底部材２２の外底面２８が流路１１の管壁１４側に押し付けられる。これにより、振動子ホルダ２０の底部材２２（音響整合層）が緩衝部材２４を介して流路１１の管壁１４に密着されるようになっている。 Further, a pressing lid 57 is disposed on the outside (right side in FIG. 2) of the lid member 43 of the vibrator holder 20 via a wave washer 56. The presser lid 57 is screwed into the housing recess 23 of the flow meter main body 13 and presses the vibrator holder 20 via the wave washer 56. As a result, in the vibrator holder 20, the outer bottom surface 28 of the bottom member 22 is pressed against the tube wall 14 side of the flow path 11 through the cylindrical member 21. As a result, the bottom member 22 (acoustic matching layer) of the vibrator holder 20 is brought into close contact with the tube wall 14 of the flow path 11 via the buffer member 24.
　図６に示されるように、振動子ホルダ２０の外面５８において、底部材２２の外底面２８から底部材２２の側面２６を経て底部材２２と筒部材２１との接合部分６０にわたる領域を少なくとも覆うように、非ガス透過性の金属薄膜６１が形成されている。具体的には、金属薄膜６１によって、底部材２２の外底面２８及び底部材２２の側面２６の全面が被覆されるとともに、底部材２２と筒部材２１との接合部分６０を基準として、筒部材２１側に数ｍｍ程度の位置まで筒部材２１の外面６２が被覆されている。本実施の形態における金属薄膜６１は、耐腐食性に優れる金属材料（具体的には金または白金）からなる薄膜であり、数μｍ程度の厚さを有する。なお、この金属薄膜６１は、金または白金の真空蒸着によって形成された蒸着膜であり、気化した腐食性ガス３を全くあるいは殆ど透過させない性質を持つ。また、底部材２２は、シリカ系セラミックスからなり、その表面は、樹脂製の管壁１４（ＰＦＡ）の外面よりも表面粗さＲａの値が大きくなっている。具体的には、底部材２２の表面粗さＲａは１μｍ以上であり、管壁１４（ＰＦＡ）の表面粗さＲａは０．１μｍ以下である。従って、底部材２２の側面２６及び外底面２８に形成される金属薄膜６１は、十分な密着強度（剥離強度）を有している。 As shown in FIG. 6, on the outer surface 58 of the vibrator holder 20, at least a region extending from the outer bottom surface 28 of the bottom member 22 through the side surface 26 of the bottom member 22 to the joint portion 60 between the bottom member 22 and the cylindrical member 21 is covered. Thus, a non-gas permeable metal thin film 61 is formed. Specifically, the metal thin film 61 covers the entire outer bottom surface 28 of the bottom member 22 and the entire side surface 26 of the bottom member 22, and the cylindrical member with reference to the joint portion 60 between the bottom member 22 and the cylindrical member 21. The outer surface 62 of the cylindrical member 21 is covered to a position of about several mm on the 21 side. The metal thin film 61 in the present embodiment is a thin film made of a metal material (specifically, gold or platinum) having excellent corrosion resistance, and has a thickness of about several μm. The metal thin film 61 is a vapor-deposited film formed by gold or platinum vacuum vapor deposition, and has a property of not allowing the vaporized corrosive gas 3 to pass through at all or almost. The bottom member 22 is made of silica-based ceramics, and the surface thereof has a surface roughness Ra that is greater than the outer surface of the resin-made tube wall 14 (PFA). Specifically, the surface roughness Ra of the bottom member 22 is 1 μm or more, and the surface roughness Ra of the tube wall 14 (PFA) is 0.1 μm or less. Therefore, the metal thin film 61 formed on the side surface 26 and the outer bottom surface 28 of the bottom member 22 has sufficient adhesion strength (peel strength).
　図１に示される超音波流量計１０は、同軸ケーブル４８を介して図示しない制御装置に接続されている。制御装置は、ＣＰＵ、ＲＯＭ、ＲＡＭ、入出力回路等からなる周知のマイクロコンピュータを中心に構成されており、同軸ケーブル４８を介して入出力される信号の演算処理を行う。 The ultrasonic flowmeter 10 shown in FIG. 1 is connected to a control device (not shown) via a coaxial cable 48. The control device is configured around a known microcomputer including a CPU, ROM, RAM, input / output circuit, and the like, and performs arithmetic processing of signals input / output via the coaxial cable 48.
　本実施の形態の超音波流量計１０では、流量計本体１３に装着された一対の超音波振動子１６を用い、流路１１の直管部１８を流れる薬液Ｗ１を介して超音波を送受信する。このとき、制御装置では、超音波の送信信号及び超音波の受信信号に基づいて、薬液Ｗ１の流れに対して正方向及び逆方向に超音波が伝搬する際の伝搬時間がそれぞれ測定される。そして、それら伝搬時間の差から薬液Ｗ１の流速が求められる。さらに、その流速を流量に変換することで、薬液Ｗ１の流量が測定される。そして、制御装置は、この測定結果に基づいて、ＣＭＰ装置に供給する薬液Ｗ１の流量を管理する。 In the ultrasonic flow meter 10 of the present embodiment, ultrasonic waves are transmitted and received through the chemical liquid W1 flowing through the straight pipe portion 18 of the flow path 11 using a pair of ultrasonic transducers 16 attached to the flow meter main body 13. . At this time, the control device measures the propagation times when the ultrasonic waves propagate in the forward direction and the reverse direction with respect to the flow of the chemical liquid W1, based on the ultrasonic transmission signal and the ultrasonic reception signal. And the flow rate of the chemical | medical solution W1 is calculated | required from the difference of those propagation times. Furthermore, the flow rate of the chemical liquid W1 is measured by converting the flow rate into a flow rate. And a control apparatus manages the flow volume of the chemical | medical solution W1 supplied to CMP apparatus based on this measurement result.
　次に、超音波流量計１０の製造方法について以下に説明する。 Next, a method for manufacturing the ultrasonic flowmeter 10 will be described below.
　先ず、筒部材２１及び底部材２２を準備する。具体的には、銅からなるパイプ材を切断して所定の長さ（本実施の形態では１５ｍｍの長さ）の筒部材２１にする。その後、切削加工等を行うことにより、筒部材２１の端部３０にＵ字状の切り欠き部４０を形成するとともに２本の細長いスリット溝４１を形成する。なおここでは、切り欠き部４０及び細長いスリット溝４１を形成した後に、パイプ材を所定の長さに切断して筒部材２１を形成してもよい。さらに、シリカ（ＳｉＯ２）を含んだ板状のセラミックスを円板状に切削加工することで、直径が１２．５ｍｍの底部材２２を形成する。なおここで、セラミックスの未焼成材料を円板状に成形した後、焼成工程を行うことで、直径が１２．５ｍｍの底部材２２を形成してもよい。 First, the cylindrical member 21 and the bottom member 22 are prepared. Specifically, a pipe member made of copper is cut into a cylindrical member 21 having a predetermined length (15 mm in this embodiment). Thereafter, by performing a cutting process or the like, the U-shaped cutout portion 40 is formed at the end portion 30 of the cylindrical member 21 and two elongated slit grooves 41 are formed. In addition, after forming the notch part 40 and the elongate slit groove | channel 41 here, the pipe member may be cut | disconnected to predetermined length, and the cylindrical member 21 may be formed. Further, the bottom member 22 having a diameter of 12.5 mm is formed by cutting a plate-like ceramic containing silica (SiO 2 ) into a disc shape. Here, the bottom member 22 having a diameter of 12.5 mm may be formed by performing a firing step after the ceramic unfired material is formed into a disk shape.
　そして、底部材２２において内底面２７となる一方の表面に超音波振動子１６の第１電極３３を接着固定する。なおここでは、超音波振動子１６の第２主面３２における第１電極３３の折り返し部分の電極３３ａにグランド線３６をはんだ接続するとともに第２電極３４に信号線３７をはんだ接続した配線付きの超音波振動子１６を予め準備する。そして、底部材２２の内底面２７と超音波振動子１６の第１電極３３の表面とのいずれか一方に接着剤を塗布した後、底部材２２の内底面２７に超音波振動子１６を接着固定する。 Then, the first electrode 33 of the ultrasonic transducer 16 is bonded and fixed to one surface which becomes the inner bottom surface 27 in the bottom member 22. Here, the ground wire 36 is solder-connected to the electrode 33a of the folded portion of the first electrode 33 on the second main surface 32 of the ultrasonic transducer 16, and the signal line 37 is connected to the second electrode 34 by soldering. An ultrasonic transducer 16 is prepared in advance. Then, after applying an adhesive to either the inner bottom surface 27 of the bottom member 22 or the surface of the first electrode 33 of the ultrasonic transducer 16, the ultrasonic transducer 16 is adhered to the inner bottom surface 27 of the bottom member 22. Fix it.
　この後、筒部材２１と底部材２２との接合工程を行う。この接合工程では、筒部材２１において切り欠き部４０及びスリット溝４１が形成されていない一方の端面と底部材２２の内底面２７における外縁部とのいずれか一方に接着剤を塗布し、それら筒部材２１と底部材２２とを接着固定する。この結果、有底筒状の振動子ホルダ２０を形成する。 Thereafter, the joining process between the tubular member 21 and the bottom member 22 is performed. In this joining step, an adhesive is applied to one of the end surface of the tubular member 21 where the notch 40 and the slit groove 41 are not formed and the outer edge portion of the inner bottom surface 27 of the bottom member 22. The member 21 and the bottom member 22 are bonded and fixed. As a result, a bottomed cylindrical vibrator holder 20 is formed.
　この後、薄膜形成工程では、金または白金の真空蒸着により、振動子ホルダ２０の外面５８に金属薄膜６１を形成する。このとき、振動子ホルダ２０の外面５８において、底部材２２の外底面２８及び側面２６に金または白金の薄膜を蒸着させるとともに、底部材２２と筒部材２１との接合部分６０を含む領域（筒部材２１の外面６２の一部を含む領域）にも金または白金の薄膜を蒸着させる。本実施の形態の振動子ホルダ２０では、底部材２２と筒部材２１との接合部分６０を基準として、筒部材２１側に数ｍｍ程度の位置まで外面５８が被覆されるように金属薄膜６１を形成する。 Thereafter, in the thin film forming step, the metal thin film 61 is formed on the outer surface 58 of the vibrator holder 20 by vacuum deposition of gold or platinum. At this time, on the outer surface 58 of the vibrator holder 20, a gold or platinum thin film is vapor-deposited on the outer bottom surface 28 and the side surface 26 of the bottom member 22, and a region (cylinder) including the joint portion 60 between the bottom member 22 and the cylindrical member 21. A thin film of gold or platinum is also deposited on a region including a part of the outer surface 62 of the member 21. In the vibrator holder 20 of the present embodiment, the metal thin film 61 is provided so that the outer surface 58 is covered to a position of about several mm on the cylindrical member 21 side with reference to the joint portion 60 between the bottom member 22 and the cylindrical member 21. Form.
　次に、筒部材２１の内面６４において、２本のスリット溝４１に挟まれた部位に、超音波振動子１６の電極３３ａから延びるグランド線３６にて露出した導線部分３６ａをはんだ接続する。そして、レセプタクル４５の接地導体５４にグランド線３６をはんだ接続するとともに、レセプタクル４５の中心導体５３に超音波振動子１６の第２電極３４から延びる信号線３７をはんだ接続する。その後、底部材２２の外底面２８にシート状の緩衝部材２４を密着配置させた状態で、流量計本体１３の収容凹部２３に振動子ホルダ２０を挿入する。またこのとき、筒部材２１におけるＵ字状の切り欠き部４０が上方に開口するよう振動子ホルダ２０を配置する。そして、切り欠き部４０にレセプタクル４５を配置し、レセプタクル固定ナット４６及びレセプタクルワッシャ４７等を用いてレセプタクル４５を流量計本体１３に固定する。さらに、収容凹部２３において、振動子ホルダ２０の後方から蓋部材４３を被せるとともに波ワッシャ５６を介して押さえ蓋５７を螺着する。この結果、押さえ蓋５７によって振動子ホルダ２０が押圧され、蓋部材４３及び筒部材２１を介して底部材２２の外底面２８が流路１１の管壁１４側に押し付けられた状態で振動子ホルダ２０が収容凹部２３に装着される。 Next, the conductive wire portion 36a exposed by the ground wire 36 extending from the electrode 33a of the ultrasonic transducer 16 is solder-connected to a portion sandwiched between the two slit grooves 41 on the inner surface 64 of the cylindrical member 21. The ground wire 36 is solder-connected to the ground conductor 54 of the receptacle 45, and the signal line 37 extending from the second electrode 34 of the ultrasonic transducer 16 is solder-connected to the center conductor 53 of the receptacle 45. Thereafter, the vibrator holder 20 is inserted into the housing recess 23 of the flow meter main body 13 in a state where the sheet-like buffer member 24 is disposed in close contact with the outer bottom surface 28 of the bottom member 22. At this time, the vibrator holder 20 is arranged so that the U-shaped notch 40 in the cylindrical member 21 opens upward. Then, the receptacle 45 is disposed in the notch 40 and the receptacle 45 is fixed to the flowmeter main body 13 using the receptacle fixing nut 46 and the receptacle washer 47. Further, in the housing recess 23, the lid member 43 is covered from the rear of the vibrator holder 20 and the pressing lid 57 is screwed through the wave washer 56. As a result, the vibrator holder 20 is pressed by the holding lid 57, and the vibrator holder 20 is pressed with the outer bottom surface 28 of the bottom member 22 pressed against the tube wall 14 side of the flow path 11 through the lid member 43 and the cylindrical member 21. 20 is mounted in the receiving recess 23.
　そして、同軸ケーブル４８の先端に設けられた同軸プラグ４９をレセプタクル４５に結合させる。さらに、流量計本体１３において、レセプタクル４５と同軸プラグ４９との結合部を覆うようにカバー部材５１を装着する。以上の工程を経て、図１に示すような超音波流量計１０が製造される。 Then, the coaxial plug 49 provided at the tip of the coaxial cable 48 is coupled to the receptacle 45. Further, in the flow meter main body 13, a cover member 51 is attached so as to cover the coupling portion between the receptacle 45 and the coaxial plug 49. Through the above steps, an ultrasonic flowmeter 10 as shown in FIG. 1 is manufactured.
　従って、本実施の形態によれば以下の効果を得ることができる。 Therefore, according to the present embodiment, the following effects can be obtained.
　（１）本実施の形態の超音波流量計１０では、振動子ホルダ２０の外面５８において、底部材２２の外底面２８から底部材２２の側面２６を経て底部材２２と筒部材２１との接合部分６０にわたる領域を含み、外面５８の一部を覆うように、金属薄膜６１が形成される。この金属薄膜６１によって振動子ホルダ２０内へのガス（薬液Ｗ１の気化ガス）の浸透が遮断される。この結果、振動子ホルダ２０内に収容された超音波振動子１６の電極３３，３４や配線（グランド線３６や信号線３７）等の腐食を回避することができる。また、本実施の形態の超音波流量計１０において、金属薄膜６１は、樹脂製の流量計本体１３側ではなく、剛体からなる振動子ホルダ２０（筒部材２１及び底部材２２）の表面に形成されている。従って、高温の薬液Ｗ１の流量を計測する場合であっても、振動子ホルダ２０の外面５８は樹脂表面のような熱膨張が生じ難いため、振動子ホルダ２０の外面５８に金属薄膜６１が密着した状態で確実に保持される。この結果、超音波流量計１０を長期間使用した場合でも、金属薄膜６１によって超音波振動子１６等の腐食を回避することができる。 (1) In the ultrasonic flowmeter 10 according to the present embodiment, the bottom member 22 and the tubular member 21 are joined to each other on the outer surface 58 of the transducer holder 20 from the outer bottom surface 28 of the bottom member 22 through the side surface 26 of the bottom member 22. The metal thin film 61 is formed so as to cover a part of the outer surface 58 including the region extending over the portion 60. The metal thin film 61 blocks the penetration of the gas (the vaporized gas of the chemical liquid W1) into the vibrator holder 20. As a result, it is possible to avoid corrosion of the electrodes 33 and 34 of the ultrasonic transducer 16 accommodated in the transducer holder 20 and the wiring (the ground wire 36 and the signal wire 37). Further, in the ultrasonic flow meter 10 of the present embodiment, the metal thin film 61 is formed on the surface of the vibrator holder 20 (the cylindrical member 21 and the bottom member 22) made of a rigid body, not on the resin flow meter main body 13 side. Has been. Accordingly, even when the flow rate of the high-temperature chemical solution W1 is measured, the outer surface 58 of the vibrator holder 20 hardly undergoes thermal expansion like the resin surface, so that the metal thin film 61 is in close contact with the outer surface 58 of the vibrator holder 20. It is securely held in the state. As a result, even when the ultrasonic flowmeter 10 is used for a long time, the corrosion of the ultrasonic transducer 16 and the like can be avoided by the metal thin film 61.
　（２）本実施の形態の超音波流量計１０では、振動子ホルダ２０において、底部材２２の内底面２７に超音波振動子１６が固定されるとともに、その内底面２７における外縁部に接合された筒部材２１によって底部材２２の外底面２８が管壁１４側に押し付けられている。この底部材２２は、超音波振動子１６と管壁１４との間に介在され、音響整合層として機能する。具体的には、底部材２２の音響インピーダンスは、超音波振動子１６よりも小さく、管壁１４よりも大きい。従って、超音波振動子１６と管壁１４との間にその底部材２２を介在させることにより、各部材間の界面における音響インピーダンスの差を小さくすることができる。さらに、底部材２２は、超音波の波長λに応じたλ／４の厚みを有する。このようにすると、超音波振動子１６から出力された超音波を管壁１４を介して薬液Ｗ１に効率よく伝搬させることができ、薬液Ｗ１の流量を正確に測定することができる。 (2) In the ultrasonic flowmeter 10 of the present embodiment, in the vibrator holder 20, the ultrasonic vibrator 16 is fixed to the inner bottom surface 27 of the bottom member 22 and is joined to the outer edge portion of the inner bottom surface 27. The outer bottom surface 28 of the bottom member 22 is pressed against the tube wall 14 by the cylindrical member 21. The bottom member 22 is interposed between the ultrasonic transducer 16 and the tube wall 14 and functions as an acoustic matching layer. Specifically, the acoustic impedance of the bottom member 22 is smaller than the ultrasonic transducer 16 and larger than the tube wall 14. Therefore, by interposing the bottom member 22 between the ultrasonic transducer 16 and the tube wall 14, the difference in acoustic impedance at the interface between the members can be reduced. Furthermore, the bottom member 22 has a thickness of λ / 4 corresponding to the wavelength λ of the ultrasonic wave. If it does in this way, the ultrasonic wave output from the ultrasonic transducer | vibrator 16 can be efficiently propagated to the chemical | medical solution W1 via the tube wall 14, and the flow volume of the chemical | medical solution W1 can be measured correctly.
　（３）本実施の形態の超音波流量計１０において、金属薄膜６１は、金または白金からなるので、腐食をもたらす薬液Ｗ１（フッ酸や硫酸などの薬液）を流路１１に流す場合であっても、その薬液Ｗ１に対して十分な耐腐食性を確保することができる。 (3) In the ultrasonic flowmeter 10 according to the present embodiment, the metal thin film 61 is made of gold or platinum, and therefore, the chemical solution W1 (chemical solution such as hydrofluoric acid or sulfuric acid) that causes corrosion flows through the flow path 11. However, sufficient corrosion resistance can be ensured for the chemical liquid W1.
　（４）本実施の形態の超音波流量計１０において、底部材２２はセラミックスであり、その表面は、樹脂製の管壁１４の外面よりも表面粗さＲａの値が大きくなっている。このようにすると、底部材２２の側面２６及び外底面２８に、密着強度（剥離強度）が高く、剥離し難い金属薄膜６１を確実に形成することができる。 (4) In the ultrasonic flowmeter 10 of the present embodiment, the bottom member 22 is made of ceramics, and the surface has a surface roughness Ra larger than that of the outer surface of the resin tube wall 14. In this way, the metal thin film 61 having high adhesion strength (peel strength) and difficult to peel can be reliably formed on the side surface 26 and the outer bottom surface 28 of the bottom member 22.
　（５）本実施の形態の超音波流量計１０において、金属薄膜６１の厚さは数μｍであり、金属薄膜６１を伝搬する超音波の波長λの１／８（２００μｍ）の厚さよりも薄く形成されている。このように、金属薄膜６１を薄く形成することにより、金属薄膜６１の表面において超音波が反射することがなく、超音波の伝搬に影響することがない。さらに、金属薄膜６１の材料費を低く抑えることができる。 (5) In the ultrasonic flowmeter 10 of the present embodiment, the thickness of the metal thin film 61 is several μm, and is thinner than 1/8 (200 μm) of the wavelength λ of the ultrasonic wave propagating through the metal thin film 61. Is formed. Thus, by forming the metal thin film 61 thin, the ultrasonic wave is not reflected on the surface of the metal thin film 61 and does not affect the propagation of the ultrasonic wave. Furthermore, the material cost of the metal thin film 61 can be kept low.
　（６）本実施の形態の超音波流量計１０では、底部材２２の外底面２８がゴム製のシート状の緩衝部材２４を介して管壁１４に密着されているので、超音波を確実に伝搬させることができる。また、緩衝部材２４は、耐熱性及び耐薬品性を有するので、長期間使用しても緩衝部材２４が劣化することなくシート形状が保持されるので、底部材２２の外底面２８を管壁１４に確実に密着させることができる。 (6) In the ultrasonic flowmeter 10 of the present embodiment, the outer bottom surface 28 of the bottom member 22 is in close contact with the tube wall 14 via the rubber sheet-like buffer member 24, so that the ultrasonic wave is reliably transmitted. Can be propagated. Further, since the buffer member 24 has heat resistance and chemical resistance, the sheet shape is maintained without deterioration of the buffer member 24 even when used for a long period of time, so that the outer bottom surface 28 of the bottom member 22 is connected to the tube wall 14. Can be securely adhered to each other.
　（７）本実施の形態では、接合工程において、筒部材２１と底部材２２とを接合して有底筒状の振動子ホルダ２０を形成した後に薄膜形成工程が実施される。従って、振動子ホルダ２０の外面５８において、筒部材２１と底部材２２との接合部分６０を塞ぐように金属薄膜６１を形成することができる。そして、金属薄膜６１によって振動子ホルダ２０内に薬液Ｗ１の気化ガスが入り込むことを防止することができ、振動子ホルダ２０内に収容された超音波振動子１６の電極３３，３４や配線３６，３７等の腐食が回避される。従って、本実施の形態によると、製品寿命の長い超音波流量計１０を効率よく確実に製造することができる。 (7) In the present embodiment, the thin film forming step is performed after the cylindrical member 21 and the bottom member 22 are bonded to form the bottomed cylindrical vibrator holder 20 in the bonding step. Accordingly, the metal thin film 61 can be formed on the outer surface 58 of the vibrator holder 20 so as to close the joint portion 60 between the tubular member 21 and the bottom member 22. Further, the vaporized gas of the chemical solution W1 can be prevented from entering the vibrator holder 20 by the metal thin film 61, and the electrodes 33 and 34 of the ultrasonic vibrator 16 accommodated in the vibrator holder 20 and the wiring 36, Corrosion of 37 etc. is avoided. Therefore, according to the present embodiment, the ultrasonic flowmeter 10 having a long product life can be manufactured efficiently and reliably.
　（８）本実施の形態の超音波流量計１０では、振動子ホルダ２０を構成する筒部材２１の端部３０側に２本のスリット溝４１が形成されており、それらスリット溝４１に挟まれた部分にグランド線３６がはんだを用いて接続されている。このようにスリット溝４１を形成すると、はんだ接続の際にはスリット溝４１間の部位から熱が逃げ難くなるため、グランド線３６のはんだ接続を容易に行うことができる。 (8) In the ultrasonic flowmeter 10 of the present embodiment, two slit grooves 41 are formed on the end 30 side of the cylindrical member 21 constituting the transducer holder 20, and are sandwiched between the slit grooves 41. A ground wire 36 is connected to the portion using solder. When the slit grooves 41 are formed in this way, it is difficult for heat to escape from the portions between the slit grooves 41 during the solder connection, and therefore the solder connection of the ground wire 36 can be easily performed.
　（９）本実施の形態では、超音波流量計１０の測定結果に基づいて、半導体の研磨処理に必要な量の薬液Ｗ１をＣＭＰ装置に確実に供給することができる。また、薬液Ｗ１は高温であるため、半導体の研磨処理を効率よく確実に行うことができる。 (9) In the present embodiment, based on the measurement result of the ultrasonic flow meter 10, the chemical solution W1 in an amount necessary for the semiconductor polishing process can be reliably supplied to the CMP apparatus. Moreover, since the chemical | medical solution W1 is high temperature, the grinding | polishing process of a semiconductor can be performed efficiently and reliably.
　なお、本発明の実施の形態は以下のように変更してもよい。 The embodiment of the present invention may be modified as follows.
　・上記実施の形態の薄膜形成工程では、金または白金の真空蒸着によって金属薄膜６１を振動子ホルダ２０の外面５８に形成するものであったが、これに限定されるものではない。ＣＶＤや無電解めっき等の他の手法により、金属薄膜６１を形成してもよい。なお、無電解めっきで金属薄膜６１を形成する場合、先ず、無電解銅めっきを行って下地層となる銅めっき層を形成した後、金または白金の無電解めっきを行う。このようにしても、振動子ホルダ２０の外面５８に、耐腐食性に優れる金または白金の薄膜を形成することができる。 In the thin film forming step of the above embodiment, the metal thin film 61 is formed on the outer surface 58 of the vibrator holder 20 by vacuum deposition of gold or platinum, but is not limited to this. The metal thin film 61 may be formed by other methods such as CVD or electroless plating. In the case where the metal thin film 61 is formed by electroless plating, first, electroless copper plating is performed to form a copper plating layer as a base layer, and then electroless plating of gold or platinum is performed. Even in this case, a thin film of gold or platinum having excellent corrosion resistance can be formed on the outer surface 58 of the vibrator holder 20.
　・上記実施の形態の薄膜形成工程では、振動子ホルダ２０において、底部材２２と筒部材２１との接合部分６０を含む外面５８の一部に金属薄膜６１を形成するものであったが、これに限定されるものではない。図７に示されるように、振動子ホルダ２０Ａの外面６２の全体に金属薄膜６１を形成してもよい。また、図８に示されるように、振動子ホルダ２０Ｂの外面５８の全体に加えて内面６５の全体にも金属薄膜６１を形成してもよい。このように金属薄膜６１を形成すると、振動子ホルダ２０Ａ，２０Ｂ内の超音波振動子１６の電極３３，３４や配線（信号線３７及びグランド線３６）等の腐食をより確実に防止することができる。 In the thin film formation process of the above embodiment, the metal thin film 61 is formed on a part of the outer surface 58 including the joint portion 60 between the bottom member 22 and the cylindrical member 21 in the vibrator holder 20. It is not limited to. As shown in FIG. 7, a metal thin film 61 may be formed on the entire outer surface 62 of the vibrator holder 20A. Further, as shown in FIG. 8, the metal thin film 61 may be formed on the entire inner surface 65 in addition to the entire outer surface 58 of the vibrator holder 20B. When the metal thin film 61 is formed in this way, corrosion of the electrodes 33 and 34 of the ultrasonic transducer 16 and the wirings (the signal line 37 and the ground line 36) in the transducer holders 20A and 20B can be more reliably prevented. it can.
　・上記実施の形態の超音波流量計１０において、振動子ホルダ２０を構成する筒部材２１は銅からなる金属製の部材であったが、これに限定されるものではない。図７や図８に示される振動子ホルダ２０Ａ，２０Ｂのように、外面５８の全体や内面６５の全体に金属薄膜６１を形成する場合、金属薄膜６１によって電気ノイズに対するシールド機能が確保される。このため、底部材２２と同様にセラミックス（剛体）によって筒部材２１を形成してもよい。 In the ultrasonic flowmeter 10 of the above embodiment, the cylindrical member 21 constituting the transducer holder 20 is a metal member made of copper, but is not limited to this. When the metal thin film 61 is formed on the entire outer surface 58 or the entire inner surface 65 as in the vibrator holders 20A and 20B shown in FIGS. 7 and 8, the metal thin film 61 ensures a shielding function against electric noise. For this reason, the cylindrical member 21 may be formed of ceramics (rigid body) similarly to the bottom member 22.
　・上記実施の形態では、底部材２２の内底面２７に超音波振動子１６を接着固定した後に、薄膜形成工程を行っていたが、これに限定されるものではない。これとは逆に、薄膜形成工程を行った後、底部材２２の内底面２７に超音波振動子１６を接着固定してもよい。 In the above embodiment, the thin film forming step is performed after the ultrasonic transducer 16 is bonded and fixed to the inner bottom surface 27 of the bottom member 22. However, the present invention is not limited to this. On the contrary, the ultrasonic transducer 16 may be bonded and fixed to the inner bottom surface 27 of the bottom member 22 after performing the thin film forming step.
　・上記実施の形態では、チタン酸ジルコン酸鉛（ＰＺＴ）からなる超音波振動子１６を用いたが、超音波振動子１６の形成材料には特に限定されるものではない。具体的には、例えば、ニオブ酸カリウムナトリウム系（ニオブ酸アルカリ系）の圧電セラミックスからなる超音波振動子を用いてもよい。また、流量計本体１３の形成材料として、フッ素樹脂（具体的には、ＰＦＡ）を用いたが、耐熱性及び耐薬品性に優れるものであれば他の樹脂材料を用いてもよい。さらに、音響整合層として機能する底部材２２の形成材料についても、超音波振動子１６の音響インピーダンスや流量計本体１３の音響インピーダンスに応じて、適宜変更してもよい。 In the above embodiment, the ultrasonic vibrator 16 made of lead zirconate titanate (PZT) is used, but the material for forming the ultrasonic vibrator 16 is not particularly limited. Specifically, for example, an ultrasonic vibrator made of a potassium sodium niobate-based (alkali niobate-based) piezoelectric ceramic may be used. Moreover, although the fluororesin (specifically, PFA) was used as the material for forming the flow meter body 13, other resin materials may be used as long as they have excellent heat resistance and chemical resistance. Furthermore, the material for forming the bottom member 22 that functions as an acoustic matching layer may be changed as appropriate according to the acoustic impedance of the ultrasonic transducer 16 and the acoustic impedance of the flowmeter body 13.
　・上記実施の形態の超音波流量計１０では、コ字状の流路１１が形成された管１２を有する流量計本体１３を用いたが、これに限定されるものではない。具体的には、直管部１８の両端がそれぞれ逆方向（例えば上側及び下側）に直角に曲がったＺ字状の流路や、それ以外の形状の流路が形成された管を有する流量計本体を用いてもよい。 In the ultrasonic flow meter 10 of the above embodiment, the flow meter main body 13 having the tube 12 in which the U-shaped flow path 11 is formed is used, but the present invention is not limited to this. Specifically, a flow rate having a Z-shaped flow path in which both ends of the straight pipe portion 18 are bent at right angles in opposite directions (for example, the upper side and the lower side) and a pipe formed with a flow path of other shapes. A meter body may be used.
　・上記実施の形態の超音波流量計１０は、ＣＭＰ装置の薬液供給ラインに用いられるものであったが、これに限定するものではない。薬液Ｗ１を用いて部品の洗浄や薬剤の生成等の処理を行う他の処理装置に超音波流量計１０を用いてもよい。 -Although the ultrasonic flowmeter 10 of the said embodiment was used for the chemical | medical solution supply line of CMP apparatus, it is not limited to this. The ultrasonic flow meter 10 may be used in other processing apparatuses that perform processing such as cleaning of parts and generation of medicines using the chemical liquid W1.
　次に、特許請求の範囲に記載された技術的思想のほかに、前述した実施の形態によって把握される技術的思想を以下に列挙する。 Next, in addition to the technical ideas described in the claims, the technical ideas grasped by the embodiment described above are listed below.
　（１）請求項１乃至１０のいずれか１項において、前記筒部材は、円筒形の銅パイプであり、円板状の前記超音波振動子よりも若干大きな内径を有していることを特徴とする超音波流量計。 (1) In any one of claims 1 to 10, the cylindrical member is a cylindrical copper pipe, and has a slightly larger inner diameter than the disk-shaped ultrasonic transducer. Ultrasonic flow meter.
　（２）技術的思想（１）において、前記筒部材には、前記超音波振動子の接地電極が電気的に接続されることを特徴とする超音波流量計。 (2) The ultrasonic flowmeter according to the technical idea (1), wherein a ground electrode of the ultrasonic transducer is electrically connected to the cylindrical member.
　（３）請求項１乃至１０のいずれか１項において、前記流体は、半導体製造装置の薬液循環ラインを流れる薬液であることを特徴とする超音波流量計。 (3) The ultrasonic flowmeter according to any one of claims 1 to 10, wherein the fluid is a chemical solution flowing in a chemical solution circulation line of a semiconductor manufacturing apparatus.
　（４）請求項１乃至１０のいずれか１項において、前記流体は、半導体製造装置の薬液循環ラインを流れる薬液としてのフッ酸または硫酸であり、前記薬液の液温は１００℃以上２００℃以下であることを特徴とする超音波流量計。 (4) In any one of claims 1 to 10, the fluid is hydrofluoric acid or sulfuric acid as a chemical solution flowing through a chemical solution circulation line of a semiconductor manufacturing apparatus, and the liquid temperature of the chemical solution is 100 ° C or higher and 200 ° C or lower. Ultrasonic flowmeter characterized by being.
　（５）請求項１乃至１０のいずれか１項において、前記流量計本体は、フッ素樹脂からなることを特徴とする超音波流量計。 (5) The ultrasonic flowmeter according to any one of claims 1 to 10, wherein the flowmeter body is made of a fluororesin.
　（６）請求項１乃至１０のいずれか１項において、前記超音波の周波数は、２ＭＨｚ以上であることを特徴とする超音波流量計。 (6) The ultrasonic flowmeter according to any one of claims 1 to 10, wherein the frequency of the ultrasonic wave is 2 MHz or more.
　（７）請求項１１において、前記薄膜形成工程では、金または白金の蒸着によって前記金属薄膜を形成することを特徴とする超音波流量計の製造方法。 (7) The method of manufacturing an ultrasonic flowmeter according to claim 11, wherein in the thin film forming step, the metal thin film is formed by vapor deposition of gold or platinum.
　（８）請求項１１において、前記薄膜形成工程では、金または白金の無電解めっきによって前記金属薄膜を形成することを特徴とする超音波流量計の製造方法。 (8) The method of manufacturing an ultrasonic flowmeter according to claim 11, wherein in the thin film forming step, the metal thin film is formed by electroless plating of gold or platinum.
　（９）請求項１１において、前記薄膜形成工程では、前記底部材の表面に無電解銅めっきを行って下地層を形成した後に、金または白金の無電解めっきを行って金または白金の薄膜を形成することを特徴とする超音波流量計の製造方法。 (9) In claim 11, in the thin film forming step, after forming an underlayer by performing electroless copper plating on the surface of the bottom member, electroless plating of gold or platinum is performed to form a gold or platinum thin film. A method of manufacturing an ultrasonic flowmeter, characterized by comprising:
　１０…超音波流量計
　１１…流路
　１２…管
　１３…流量計本体
　１４…管壁
　１６…超音波振動子
　２０，２０Ａ，２０Ｂ…振動子ホルダ
　２１…筒部材
　２２…底部材
　２４…緩衝部材
　２６…側面
　２７…内底面
　２８…外底面
　５８…外面
　６０…接合部分
　６１…金属薄膜
　６５…内面 DESCRIPTION OF SYMBOLS 10 ... Ultrasonic flow meter 11 ... Flow path 12 ... Pipe 13 ... Flow meter main body 14 ... Tube wall 16 ... Ultrasonic vibrator 20, 20A, 20B ... Vibrator holder 21 ... Cylindrical member 22 ... Bottom member 24 ... Buffer member 26 ... Side surface 27 ... Inner bottom face 28 ... Outer bottom face 58 ... Outer face 60 ... Joint portion 61 ... Metal thin film 65 ... Inner face

Claims (11)

  1. 　流体が流れる流路を形成する管を有する樹脂製の流量計本体と、
    　前記流路における上流側位置及び下流側位置にて各々管壁を隔てて対向配置された位置関係にあり、前記管壁を介して超音波の送受信を行う一対の超音波振動子と、
    　剛体からなる有底筒状の部材であり、前記超音波振動子をそれぞれ収納した状態で前記管壁の外側に装着される一対の振動子ホルダと
    を備え、前記一対の超音波振動子間で送受信される超音波の伝搬時間の差に基づいて、前記流体の流量を計測する超音波流量計であって、
    　前記振動子ホルダは、
    　側面と、前記超音波振動子が固定される内底面と、前記内底面の反対側に位置する外底面とを有する板状に形成され、前記超音波振動子と前記管壁との間に介在される音響整合層として機能する底部材と、
    　前記底部材の前記内底面における外縁部に接合され、前記外底面を前記管壁側に押し付ける筒部材と
    を備えて構成され、
    　前記振動子ホルダの外面において、前記底部材の前記外底面から前記底部材の前記側面を経て前記底部材と前記筒部材との接合部分にわたる領域を少なくとも覆うように、非ガス透過性の金属薄膜を形成した
    ことを特徴とする超音波流量計。     A resin flowmeter body having a tube forming a flow path through which the fluid flows;
    A pair of ultrasonic transducers that are arranged to face each other across the tube wall at an upstream position and a downstream position in the flow path, and that transmit and receive ultrasonic waves through the tube wall;
    A bottomed cylindrical member made of a rigid body, comprising a pair of transducer holders mounted on the outside of the tube wall in a state in which the ultrasonic transducers are respectively housed, and between the pair of ultrasonic transducers An ultrasonic flowmeter that measures the flow rate of the fluid based on a difference in propagation time of transmitted and received ultrasonic waves,
    The vibrator holder is
    It is formed in a plate shape having a side surface, an inner bottom surface to which the ultrasonic transducer is fixed, and an outer bottom surface located on the opposite side of the inner bottom surface, and is interposed between the ultrasonic transducer and the tube wall A bottom member that functions as an acoustic matching layer,
    A cylindrical member that is joined to the outer edge portion of the inner bottom surface of the bottom member and presses the outer bottom surface against the tube wall side;
    On the outer surface of the vibrator holder, a non-gas permeable metal thin film is formed so as to cover at least a region extending from the outer bottom surface of the bottom member through the side surface of the bottom member to the joint portion of the bottom member and the cylindrical member. Ultrasonic flowmeter characterized by forming.
  2. 　前記振動子ホルダにおける前記外面の全体に、前記金属薄膜を形成したことを特徴とする請求項１に記載の超音波流量計。 The ultrasonic flowmeter according to claim 1, wherein the metal thin film is formed on the entire outer surface of the vibrator holder.
  3. 　前記振動子ホルダにおける前記外面の全体及び内面の全体に、前記金属薄膜を形成したことを特徴とする請求項１に記載の超音波流量計。 The ultrasonic flowmeter according to claim 1, wherein the thin metal film is formed on the entire outer surface and the entire inner surface of the vibrator holder.
  4. 　前記金属薄膜は、金または白金からなることを特徴とする請求項１乃至３のいずれか１項に記載の超音波流量計。 4. The ultrasonic flowmeter according to claim 1, wherein the metal thin film is made of gold or platinum.
  5. 　前記底部材は、音響インピーダンスが前記超音波振動子よりも小さく、かつ前記管壁よりも大きいセラミックスであることを特徴とする請求項１乃至４のいずれか１項に記載の超音波流量計。 The ultrasonic flowmeter according to any one of claims 1 to 4, wherein the bottom member is a ceramic having an acoustic impedance smaller than that of the ultrasonic transducer and larger than that of the tube wall.
  6. 　前記流量計本体の流路は、ストレート状に延設された直管部を有するとともにその直管部の両端が直角に曲がった形状の管路であり、
    　前記直管部における上流側及び下流側の各端部に前記一対の超音波振動子が設けられていることを特徴とする請求項１乃至５のいずれか１項に記載の超音波流量計。     The flow passage of the flowmeter body has a straight pipe portion extending in a straight shape and is a pipe passage having a shape in which both ends of the straight pipe portion are bent at right angles,
    6. The ultrasonic flowmeter according to claim 1, wherein the pair of ultrasonic transducers is provided at each of an upstream end portion and a downstream end portion of the straight pipe portion.
  7. 　前記底部材の表面は、前記管壁の外面よりも表面粗さの値が大きいことを特徴とする請求項１乃至６のいずれか１項に記載の超音波流量計。 The ultrasonic flowmeter according to any one of claims 1 to 6, wherein the surface of the bottom member has a surface roughness value larger than that of the outer surface of the tube wall.
  8. 　前記底部材は、前記超音波の波長λに応じたλ／４の厚みを有することを特徴とする請求項１乃至７のいずれか１項に記載の超音波流量計。 The ultrasonic flowmeter according to any one of claims 1 to 7, wherein the bottom member has a thickness of λ / 4 corresponding to a wavelength λ of the ultrasonic wave.
  9. 　前記金属薄膜は、前記超音波の波長λの１／８の厚さよりも薄く形成されることを特徴とする請求項１乃至８のいずれか１項に記載の超音波流量計。 The ultrasonic flowmeter according to any one of claims 1 to 8, wherein the metal thin film is formed to be thinner than １ ／ of the wavelength λ of the ultrasonic wave.
  10. 　前記振動子ホルダにおいて前記金属薄膜を形成した前記外底面は、耐熱性及び耐薬品性を有するゴム製のシート状の緩衝部材を介して前記管壁に密着されることを特徴とする請求項１乃至９のいずれか１項に記載の超音波流量計 2. The outer bottom surface on which the metal thin film is formed in the vibrator holder is in close contact with the tube wall via a rubber sheet-like buffer member having heat resistance and chemical resistance. The ultrasonic flowmeter according to any one of 1 to 9
  11. 　請求項１乃至１０のいずれか１項に記載の超音波流量計を製造する方法であって、
    　前記筒部材と前記底部材とを接着剤を用いて接合し、前記有底筒状の振動子ホルダを形成する接合工程と、
    　前記接合工程の後、前記振動子ホルダの外面に、非ガス透過性の金属薄膜を形成する薄膜形成工程と
    を含むことを特徴とする超音波流量計の製造方法。     A method for manufacturing the ultrasonic flowmeter according to any one of claims 1 to 10,
    Joining the cylindrical member and the bottom member using an adhesive, and forming the bottomed cylindrical vibrator holder;
    A method of manufacturing an ultrasonic flowmeter, comprising: a thin film forming step of forming a non-gas permeable metal thin film on the outer surface of the vibrator holder after the joining step.
PCT/JP2014/066628 2014-06-24 2014-06-24 Ultrasonic flowmeter and method for manufacturing same WO2015198386A1 (en)

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