JP4305543B2 - Ultrasonic transceiver and ultrasonic flow meter using the same - Google Patents

Description

  The present invention relates to an ultrasonic transmitter / receiver used for an ultrasonic flowmeter for measuring a flow rate of a fluid.

  Conventionally, as shown in FIG. 10, this type of ultrasonic transmitter / receiver includes a lid portion of a conductive sealing case 23, a square columnar piezoelectric element 24 on the inner wall surface of the lid portion, and a matching layer on the outer wall surface of the lid portion. The ultrasonic transmitter / receiver 26 is configured by fixing 25 with an adhesive and forming desired wiring and drive terminals in the lower open portion of the sealed case 23. Here, the matching layer 25 has a structure in which a first layer made of a porous material and a second layer of filler material are stacked (for example, see Patent Document 1).

Also, as shown in FIG. 11, a protective film 27 made of an epoxy resin is adhesively applied to the surface of the matching layer, or the side wall portion of the case and a part of the side wall of the matching layer are covered as shown in FIG. In some cases, the vibration regulating body 28 is provided (see, for example, Patent Document 2).
JP 2004-45389 A Japanese Patent No. 3518268

  However, in the configuration of the conventional ultrasonic transmitter / receiver, the surface or end of the matching layer that is bonded to the outer wall surface of the top of the case is exposed. Abnormality of ultrasonic transmitter / receiver output characteristics or ultrasonic output characteristics do not appear with normal sensitivity due to damage caused by direct contact with human fingers, foreign matter adhesion, or destruction of the matching layer due to dropping of the ultrasonic transmitter / receiver Had problems.

  In addition, in the method of directly applying a protective film to the surface of the matching layer for the purpose of preventing damage to the matching layer, it is suitable from the frequency of the ultrasonic wave used in order to reduce the transmission / reception characteristics of the ultrasonic transducer. There is a problem that it is difficult to set the coating conditions and the work management for managing the conditions that the material and thickness of the protective film applied to the matching layer must be designed and selected. In terms of providing a vibration regulating body on the side wall, it is possible to suppress the vibration in the lateral direction of the matching layer and prevent the generation of unnecessary vibration modes, but it does not prevent mechanical damage to the surface of the matching layer. It was.

  The present invention solves the above-mentioned conventional problems, and prevents direct contact to the matching layer during the manufacturing process or incorporation into the flow meter, and damage to the matching layer such as chipping or cracking of the matching layer. It is an object of the present invention to provide an ultrasonic transmitter / receiver that improves the reliability of preventing foreign matter adhesion and stabilizes the transmission / reception output characteristics and an ultrasonic flowmeter using the ultrasonic transmitter / receiver.

In order to solve the above-described conventional problems, an ultrasonic transmitter / receiver according to the present invention is an ultrasonic transducer that has an electrical connection form with a piezoelectric body attached to the inner surface of the top of a metal cylindrical case and is sealed. An ultrasonic transmitter / receiver for transmitting or receiving an ultrasonic wave having a transmission / reception sensitivity improved by attaching an acoustic matching layer made of a porous body or the like to the top surface, wherein the ultrasonic transmitter / receiver is around the side wall surface of the cylindrical case And a protective cover that covers the surface of the acoustic matching layer, the top surface of the protective cover is provided with an opening having substantially the same shape as the acoustic matching layer, and a predetermined surface area for the surface area of the acoustic matching layer. As long as the opening area can be secured, a shielding portion for preventing damage to the acoustic matching layer is formed.

  According to the above invention, the surface of the acoustic matching layer for enhancing the transmission / reception sensitivity is covered with the protective cover provided with the shielding portion so that the finger cannot be contacted, and the ultrasonic radiation efficiency is ensured to be a predetermined value or more. Since the opening area is secured, direct contact to the acoustic matching layer during the manufacturing process and incorporation into the flow meter is avoided, damage such as chipping and cracking of the matching layer, and foreign matter on the matching layer surface. Adhesion can be prevented, transmission / reception sensitivity can be maintained at a desired sensitivity, and ultrasonic transmission / reception can be performed stably.

  In the ultrasonic transceiver according to the present invention, the protective cover that covers the surface of the acoustic matching layer is projected higher than the thickness of the side wall of the acoustic matching layer to form a protrusion for preventing damage to the acoustic matching layer.

  According to the above invention, by forming the protruding portion, it is possible to avoid a finger or the like directly contacting the acoustic matching layer during the manufacturing process or incorporation into the flowmeter, and in front of the radiation surface of the matching layer. Since there is no shield, the radiation efficiency can be maximized, and the stability of transmission / reception sensitivity can be enhanced while preventing damage to the matching layer with a simple configuration.

  Moreover, the ultrasonic flowmeter of the present invention has a matching layer breakage preventing means for preventing the acoustic matching layer from being broken when the ultrasonic transceiver is attached to the gas flow path. Avoid direct contact with the acoustic matching layer during installation, prevent damage to the matching layer such as chipping, cracking, and adhesion of foreign matter to the matching layer surface, and maintain transmission / reception sensitivity at the desired sensitivity. It is possible to perform accurate flow measurement by stably transmitting and receiving ultrasonic waves.

  According to the present invention, direct contact to the acoustic matching layer during the manufacturing process and incorporation into the flow meter is avoided, and damage such as chipping and cracking of the matching layer and foreign matter adhesion to the matching layer surface are prevented. In addition, the transmission / reception sensitivity can be maintained at a desired sensitivity, and ultrasonic transmission / reception can be performed stably.

The present invention attaches an acoustic matching layer made of a porous material or the like to the top surface of an ultrasonic transducer that has an electrical connection with a piezoelectric body attached to the inner surface of the top of a metal cylindrical case and is sealed. An ultrasonic transmitter / receiver that transmits or receives ultrasonic waves with enhanced transmission / reception sensitivity, the ultrasonic transmitter / receiver comprising a protective cover that covers the periphery of the side wall surface of the cylindrical case and the surface of the acoustic matching layer, The top surface of the protective cover is provided with an opening having substantially the same shape as the acoustic matching layer, and within a range in which a predetermined opening area predetermined with respect to the surface area of the acoustic matching layer can be secured. It is characterized in that a shielding part for preventing damage is formed.

  Then, cover the surface of the acoustic matching layer to increase the sensitivity of transmission and reception with a protective cover provided with a shielding part so that fingers cannot be touched, and secure an opening area to ensure the radiation efficiency of ultrasonic waves over a predetermined value Therefore, it avoids direct contact with the acoustic matching layer during the manufacturing process and when it is installed in the flow meter, and prevents damage such as chipping and cracking of the matching layer and adhesion of foreign matter to the surface of the matching layer. In addition, the transmission / reception sensitivity can be maintained at a desired sensitivity, and ultrasonic transmission / reception can be performed stably.

Further, the invention is characterized in that a protective cover on the surface of the acoustic matching layer is provided on the surface of the matching layer while maintaining a predetermined distance from the surface of the matching layer.

  By providing a protective cover without directly contacting the matching layer surface, it is possible to improve the stability of transmission / reception sensitivity while preventing damage to the matching layer without attenuating the ultrasonic vibration of the matching layer surface. .

The invention is characterized in that the top surface of the protective cover on the surface of the acoustic matching layer has a single letter shape, a cross letter shape, or a ring shape.

  Further, it is possible to provide a protective cover shape that satisfies both the damage prevention of the matching layer and the stability of the transmission / reception sensitivity.

In addition , when the top surface of the protective cover is a single character, the invention restricts the mounting position of the protective cover so as to correspond to the surface shape of the piezoelectric body fixed to the inner wall surface of the cylindrical case. It is a feature.

  Then, the direction of the surface shape of the piezoelectric body can be known by confirming the direction of the shape of the surface of the piezoelectric body that is adhered to the inner wall surface of the cylindrical case and cannot be seen from the outside, and the direction of the protective cover provided on the matching layer surface. Since the transmission and reception characteristics of a pair of ultrasonic transducers installed in an ultrasonic flowmeter installed at intervals in the fluid flow direction can be transmitted and received, the direction of the shape surface of the piezoelectric body is always made uniform. It becomes possible.

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

(Embodiment 1)
FIG. 1 shows a cross-sectional view of an ultrasonic transceiver according to Embodiment 1 of the present invention.

In FIG. 1, an ultrasonic transmitter / receiver 1 includes a piezoelectric body 4 bonded to the inner surface of a top portion 3 of a cylindrical case 2 made of a conductive material with an epoxy resin and an acoustic matching bonded to the outer surface of the top portion 3. An opening having substantially the same shape as the acoustic matching layer 5 fitted so as to be integrated along the side wall portion 6 of the cylindrical case 2 while keeping a predetermined distance from the surface of the acoustic matching layer 5. And a protective cover 7 having

The acoustic matching layer 5 has a structure in which a porous ceramic body containing pores and a dry gel of organic glass infiltrated into the pores. In order to bond and fix the acoustic matching layer 5 and the top 3 of the cylindrical case 2, an epoxy adhesive was used. The outer diameter of the acoustic matching layer 5 is 10.8 mm, and the thickness and 1 mm.

  The piezoelectric body 4 has a prism shape of about 7.4 mm square, and electrodes formed by firing with a silver paste or the like are formed on the upper and lower surfaces thereof.

  Moreover, the lower opening part of the cylindrical case 2 is obstruct | occluded with the terminal board 9 which connected one terminal 8a. The other terminal 8 b penetrates the terminal plate 9 through an electrical insulating material 10 such as a hermetic seal, and is connected to an electrode on the lower surface of the piezoelectric body 4 through a conductor 11.

  The conductor 11 is a conductive material in which metal particles or the like are mixed with rubber, and electrically connects the lower surface electrode of the piezoelectric body 4 and the terminal 8b. The other terminal 8 a is directly fixed to the conductive terminal plate 9 and is electrically connected to the upper surface electrode of the piezoelectric body 4 through the cylindrical case 2.

  In the oscillation operation of the ultrasonic transceiver 1, the piezoelectric body 4 is vibrated at about 500 KHz, the vibration is transmitted to the cylindrical case 2 and propagated to the acoustic matching layer 5, and the vibration of the acoustic matching layer 5 is transmitted to the acoustic matching layer 5. It is transmitted as a sound wave to the fluid in contact.

  Similarly, the receiving operation is opposite to the propagation flow described above, and the acoustic matching layer 5 senses the sound wave that has passed through the fluid, and the piezoelectric body 5 vibrates through the cylindrical case 2, and the terminals 8 a and 8 b. Detected as output voltage between.

  The role of the acoustic matching layer 5 of the ultrasonic transceiver 1 is to efficiently propagate the vibration from the piezoelectric body 4 into the fluid. For this reason, it is necessary to use a material having a small acoustic impedance Z defined by the product of the sound velocity C and the density ρ. Therefore, the acoustic matching layer 5 used in the first embodiment uses a configuration in which many bubbles are contained in the ceramic, and further, a dry gel of organic glass that increases the propagation efficiency of sound waves is formed in the bubbles. To do. The acoustic matching layer 5 having such a configuration has a very small density of about 0.3. In addition, in order to efficiently perform ultrasonic transmission into the fluid and reception of the ultrasonic waves from the fluid, the acoustic matching layer 5 in the ultrasonic transmitter / receiver 1 must have an exposed configuration.

  The configuration in which the acoustic matching layer 5 having a low density is exposed causes the acoustic matching layer 5 to be damaged immediately by external mechanical stress. Risk of destroying the acoustic matching layer 5 by hitting the surface or side wall of the acoustic matching layer 5 during the operation of installing the ultrasonic transmitter / receiver 1 in a flow rate measuring device that measures the flow of fluid. There is. In addition, the surface or side wall of the acoustic matching layer 5 is brought into contact with a person's finger or the like during the same operation, which may cause foreign matter to adhere. In order to avoid this, conventionally, a method of coating the surface of the acoustic matching layer 5 with a resin material or paint on the surface or side wall portion is employed. In view of the transmission / reception characteristics of the ultrasonic transmitter / receiver 1, it is preferable that there is no coating film for the acoustic matching layer because the ultrasonic wave transmission / reception intensity on the surface of the layer is attenuated. Also, it is not appropriate to install a shield in contact with the matching layer surface for the same reason.

  Therefore, in the ultrasonic transceiver 1 according to Embodiment 1 of the present invention, the protective cover 7 is installed at a predetermined distance from the surface of the acoustic matching layer 5.

As shown in FIG. 2, the shape of the protective cover 7 having an opening having substantially the same shape as the acoustic matching layer 5 has a predetermined opening area that is predetermined with respect to the surface area of the acoustic matching layer 5. A shield 7a for preventing damage to the acoustic matching layer 5 is formed within a range that can be secured, and the shape is formed as a single letter, a cross, or a ring, and a human finger directly contacts the surface of the acoustic matching layer 5 In addition, the surface of the matching layer and the side wall portion from the outside can be protected. They are a single-character protective cover 12, a cross-shaped protective cover 13, and a ring-shaped protective cover 14, respectively. The protective cover was made of a polycarbonate resin material. In addition, the material of this protective cover is not necessarily limited to the said conditions, The thickness, material, and shape of the protective cover 7 can be suitably changed and comprised.

  Moreover, the distance of the cover installed on the surface from the surface of the acoustic matching layer 5 was made into 0.5-1 mm or less. This distance is limited to this value when the surface of the matching layer is protected without directly contacting the surface of the protective cover 7 and the matching layer 5 is protected, and deterioration of the transmission / reception sensitivity characteristics of the ultrasonic transceiver 1 is not a problem. I don't mean.

  Further, the protective cover 7 has been installed in the ultrasonic transmitter / receiver 1 by using the side wall portion of the cylindrical case 2 of the ultrasonic transmitter / receiver 1, but as shown in FIG. Even if the side wall protective cover 16 is formed using 3, there is no problem in protecting the matching layer 5, so this configuration may be used.

  In FIG. 4, the protective cover 7 installed on the top 3 of the cylindrical case 2 is fixed by being bonded to the side wall 15 or the top 3 of the matching layer 5 with an epoxy adhesive. This may be achieved by fixing the side wall protective cover 16 using the top 3 of the cylindrical case 2 and does not necessarily have to be adhered to the side wall 15 of the matching layer 5. The shape of the surface of the matching layer 5 of the protective cover 7 may be a single letter, a cross, or a ring. However, the protective cover 7 is a side wall protective cover 16 that is formed only on the periphery so as to be thicker than the side wall 15 of the matching layer 5. There is no problem.

  In this way, the sensitivity output of the ultrasonic transceiver 1 provided with the protective cover 7 was measured. The matching layer 5 of the used ultrasonic vibrator 1 is formed by infiltrating a dry gel of organic glass into a ceramic porous body, and the shape covering the surface of the matching layer 5 of the protective cover 7 is a single character shape 12 or a cross character shown in FIG. Shape 13 and ring shape 14. Further, the output characteristics were compared using the ultrasonic vibrator 1 in which the side wall protective cover 16 having a thickness higher than the thickness of the side wall portion 15 of the matching layer 5 as shown in FIG.

  This is one in which an epoxy material is applied to the side wall portion of the acoustic matching layer 5 and the cylindrical side wall protective cover 7 is bonded and fixed.

  The results of measuring the sensitivity output are shown in FIG. The horizontal axis of the graph shows the acoustic matching when various protective covers calculated by subtracting the protective area occupied by the protective covers of various shapes provided on the surface of the acoustic matching layer 5 from the surface area of the acoustic matching layer 5 are installed. The opening area on the surface of the layer 5 is shown. The vertical axis of the graph shows the sensitivity output value when various protective covers are installed for the area value.

  A method for measuring the sensitivity output will be described. Two ultrasonic transmitters / receivers arranged on a straight line so that the acoustic matching layer surface is opposed to the upper and lower surfaces of the cylinder with a distance of 71 mm and excluding the external environment, one of which is a reference ultrasonic transmitter / receiver, The other is a normal ultrasonic transmitter / receiver, and an ultrasonic transmitter / receiver provided with the side wall protective cover 16 on the acoustic matching layer 5 in the present embodiment, and a protective cover for each of the single character shape 12, the cross shape 13, and the ring shape 14. 7 is an ultrasonic transmitter / receiver 1 having a matching layer, and a maximum output voltage value obtained by measuring a transmission output transmitted from the ultrasonic transmitter / receiver 1 of the present invention for a predetermined time as a reception sensitivity by a reference ultrasonic transmitter / receiver. Is the sensitivity output.

  From the results of FIG. 5, from the descending order of sensitivity output, there was no protective cover, a side wall protective cover, a single character shape, a cross shape, and a ring shape 14.

  This indicates that the output of the ultrasonic transmitter / receiver is reduced in proportion to the protection area covering the surface of the matching layer, and the sensitivity output decreases.

  If the sensitivity output of the ultrasonic transmitter / receiver with the protective cover is within Δ30% compared to the sensitivity output value without the protective cover, there is no practical problem as an ultrasonic transmitter / receiver.

  In the case of FIG. 5, the sensitivity output value of the ultrasonic transmitter / receiver including the ring-shaped protective cover 14 is 43.2 (mV) with respect to the sensitivity output value 60 (mV) without the protective cover, and the output decreases. Was Δ28%.

  Since the outer diameter of the surface of the matching layer 5 is 10.8 (mm), the opening area is 91.6 (mm 2). Since the protection area of the ring shape 14 is 13.6 (mm 2), the opening area of the surface of the matching layer 5 on which the ring shape 14 is mounted is 78 (mm 2). If the protective case 7 located on the surface of the matching layer 5 has a shape area of about 14.8% or less with respect to the opening area of the matching layer, the sensitivity output of the ultrasonic transmitter / receiver 1 having no practical problem is maintained. be able to.

  Thus, if the surface shape of the protective case 7 is determined in consideration of the ultrasonic transmission / reception area on the surface of the matching layer 5, the fingertip of the person to the matching layer 5, etc. while maintaining the sensitivity output of the ultrasonic transmitter / receiver 1. It is possible to prevent damage to the matching layer 5 such as destruction due to direct contact, adhesion of foreign matter, and dropping or bumping of the ultrasonic transceiver 1.

  The matching layer 5 used here was constituted by infiltrating a dry gel of organic glass into a ceramic porous body. For example, a glass hollow sphere was dispersed and mixed in an epoxy resin material and solidified. The material condition of the matching layer is not limited to the above.

  As described above, in the present embodiment, by providing a side wall cover on the side wall portion of the matching layer or a protective cover having a certain shape on the surface of the matching layer, preventing damage to the matching layer and adhesion of foreign substances, An ultrasonic transmitter / receiver that maintains a transmission / reception sensitivity output can be realized.

(Embodiment 2)
FIG. 6 is a perspective view of the ultrasonic transceiver equipped with the one-letter-shaped protective cover 12 according to the second embodiment of the present invention as viewed from above.

  6 is arranged on the surface of the matching layer 5 bonded to the top 3 of the cylindrical case 2 of the ultrasonic transceiver 1. In FIG. 6, for convenience of explanation, the bonding surface of the piezoelectric body 4 bonded to the inside of the cylindrical case 2 with an epoxy resin is shown through.

  As shown in FIG. 6 and FIG. 7, the vibration oscillation surface of the piezoelectric body 4 used in the ultrasonic transmitter / receiver 1 is provided with a groove on the surface bonded to the inner surface of the cylindrical case 2. In a rectangular parallelepiped piezoelectric body, depending on the frequency to be used, thickness longitudinal vibration and spread vibration are mixed, so that it is not possible to efficiently transmit and receive ultrasonic waves transmitted from the piezoelectric body. Therefore, a groove 17 is provided in the piezoelectric body 4 in order to make the thickness longitudinal vibration a main mode. The dimensions such as the number and depth of the grooves 17 are determined based on the characteristics of the ultrasonic transceiver 1 and the structural strength of the piezoelectric body 4.

  The direction of the groove 17 in the piezoelectric body 4 of the ultrasonic transmitter / receiver cannot be known from the appearance of the ultrasonic transmitter / receiver 1 because the piezoelectric body 4 is bonded and fixed to the cylindrical case 2.

  FIG. 8 shows a gas flow rate measuring device 18 for measuring a gas flow rate and the like as an example of an ultrasonic flow meter using the ultrasonic transceiver 1 according to the present invention. FIG. 9 shows a propagation state of ultrasonic waves oscillated from the surface of the piezoelectric body 4 provided with the grooves 17.

  It is known that the direction of the groove 17 propagates in a fan shape as the arrow 19 indicates the propagation direction of the ultrasonic wave radiated from the piezoelectric body 4. When the ultrasonic transmitter / receiver 1 of the piezoelectric body 4 having the propagation direction as described above is used in the gas flow rate measuring device 18 as shown in FIG. 8, the gas as the fluid in the flow path 20 through which the fluid flows flows in the direction 21. On the other hand, it is provided facing the upstream side and the downstream side. In the direction 22 of propagation of ultrasonic waves transmitted and received by each ultrasonic transceiver 1, the ultrasonic propagation direction is the same, so that the pair of ultrasonic transceivers 1 can efficiently transmit and receive without reducing the propagation intensity. Can be expressed. Then, the transmission / reception direction of the ultrasonic transmitter / receiver 1 is controlled, the propagation time in each direction is measured by the measurement circuit 23, the measurement data is sent to the flow rate calculation means 24, and the flow rate is obtained using a predetermined calculation process.

  In the gas flow measuring device 18, if the upstream and downstream ultrasonic transmitters / receivers 1 are arranged in a state where the formation direction of the groove 17 of the piezoelectric body 4 is shifted by 90 degrees, the ultrasonic waves transmitted / received to / from each other are transmitted. Since the propagation direction is shifted by 90 degrees, the propagation efficiency of ultrasonic waves may be reduced, and the measurement accuracy may be reduced. An instrumental difference in the flow rate measurement accuracy of the gas flow rate measuring device 18 may occur in the installation direction of the ultrasonic transducer 1.

  According to Embodiment 2 of the present invention, the protective cover 7 is disposed so as to have a correlation with the shape of the protective cover 7 disposed on the surface of the acoustic matching layer 5 and the position of the piezoelectric body 4 in the groove direction. The groove direction of the piezoelectric body 4 can be determined from the appearance of the installed ultrasonic transceiver 1.

  Thereby, since the arrangement | positioning direction of a pair of ultrasonic transmitter / receiver 1 installed in the fluid measuring apparatus 18 can be fixed, the flow measuring apparatus with high reliability of flow measurement is realizable.

  Furthermore, the protective cover 7 protects the acoustic matching layer 5 even when the ultrasonic vibrator 1 is attached to the gas flow path 19 in the gas flow measuring device 18, thereby preventing damage to the matching layer of the ultrasonic transceiver 1. The ultrasonic transceiver 1 can be safely incorporated.

  In FIG. 6, the single character shape 12 is used for the protective case 7 of the ultrasonic vibrator 1, but the relative positional relationship between the direction of the groove 17 of the piezoelectric body 4 of the ultrasonic vibrator 1 and the surface shape of the protective case 7 is determined. In this case, the surface shape of the protective case 7 is not limited to the single character shape 12, and can be configured by changing the shape as appropriate.

  As described above, according to the present invention, the surface of the acoustic matching layer for enhancing transmission / reception sensitivity is covered with a protective cover provided with a shielding portion so that a finger or the like cannot be contacted, and the radiation efficiency of ultrasonic waves is set to a predetermined value. Since the opening area for ensuring the above is ensured, direct contact to the acoustic matching layer during the manufacturing process and incorporation into the flow meter is avoided, and damage such as chipping, cracking, and matching of the matching layer is avoided. Adherence of foreign matter to the surface of the layer can be prevented, transmission / reception sensitivity can be maintained at a desired sensitivity, and ultrasonic transmission / reception can be performed stably.

  Further, the ultrasonic flowmeter of the present invention has a matching layer breakage preventing means for preventing the acoustic matching layer from being broken when the ultrasonic transceiver is attached to the gas flow path. Avoid direct contact with the acoustic matching layer during installation to prevent damage to the matching layer such as chipping, cracking, and foreign matter adhesion to the matching layer surface, and to maintain the desired transmission / reception sensitivity. It is possible to perform accurate flow measurement by stably transmitting and receiving ultrasonic waves.

  As described above, the ultrasonic transmitter / receiver according to the present invention and the ultrasonic flowmeter using the ultrasonic transmitter / receiver are equipped with a protective cover. In addition, it is possible to realize a fluid flow measuring device that can protect against damage and maintain sensitivity output as an ultrasonic transmitter / receiver and that has a small instrumental difference in flow rate measurement accuracy.

Sectional drawing of the ultrasonic transmitter-receiver in Embodiment 1 of this invention Plan view of the surface shape of the protective cover in the same embodiment Sectional drawing of the ultrasonic transmitter-receiver which mounted the side wall cover in the embodiment Sectional drawing of the ultrasonic transmitter-receiver which has a protective cover using the cylindrical case top part in the embodiment The figure which shows the result of the sensitivity output change in the same embodiment The partial plane perspective view of the ultrasonic transmitter-receiver in Embodiment 2 of this invention Perspective view of piezoelectric body in the same embodiment Schematic of the gas flow rate measuring device in the same embodiment Conceptual diagram of ultrasonic wave propagation direction oscillating from piezoelectric body in the same embodiment Cross-sectional view of a conventional ultrasonic transceiver Cross-sectional view of a conventional ultrasonic transceiver Cross-sectional view of a conventional ultrasonic transceiver

DESCRIPTION OF SYMBOLS 1 Ultrasonic vibrator 2 Cylindrical case 5 Matching layer 7 Protective cover 12 Single character-shaped protective cover 13 Cross-shaped protective cover 14 Ring-shaped protective cover 16 Side wall protective cover 17 Groove 18 Gas flow measuring device

Claims (6)

Transmission and reception sensitivity is improved by attaching an acoustic matching layer made of a porous material or the like on the top surface of the ultrasonic transducer that has an electrical connection with the piezoelectric body attached to the inner surface of the top of the metallic cylindrical case and is sealed. An ultrasonic transceiver for transmitting or receiving enhanced ultrasonic waves,
The ultrasonic transceiver includes a protective cover that covers the periphery of the side wall surface of the cylindrical case and the surface of the acoustic matching layer,
The top surface of the protective cover is provided with an opening having substantially the same shape as the acoustic matching layer, and within a range in which a predetermined opening area predetermined with respect to the surface area of the acoustic matching layer can be secured. An ultrasonic transmitter / receiver with a shield to prevent damage. The ultrasonic transceiver according to claim 1, wherein a protective cover on the surface of the acoustic matching layer is provided on the surface of the matching layer while maintaining a predetermined distance from the surface of the matching layer. The ultrasonic transmitter / receiver according to claim 1 or 2 , wherein the top surface of the protective cover on the surface of the acoustic matching layer has a single letter shape, a cross letter shape, or a ring shape. 4. The super-capacitor according to claim 3, wherein when the top surface shape of the protective cover is a single character, the mounting position of the protective cover is regulated so as to correspond to the surface shape of the piezoelectric body fixed to the inner wall surface of the cylindrical case. Sonic transceiver. The ultrasonic transmitter / receiver according to any one of claims 1 to 4, wherein the protective cover is provided in the cylindrical case using a top part or a side wall part of the cylindrical case . An ultrasonic flowmeter comprising the ultrasonic transceiver according to any one of claims 1 to 5,
From the gas flow path through which the gas flows, a pair of ultrasonic transmitters / receivers that are attached to the gas flow path and transmit / receive ultrasonic waves, a measurement circuit that measures the ultrasonic propagation time between the ultrasonic transmitters / receivers, and the measurement circuit Flow rate calculating means for calculating the flow rate based on the signal of
The ultrasonic transmitter / receiver is an ultrasonic flowmeter having a matching layer breakage preventing means for preventing the acoustic matching layer from being broken when being attached to the gas flow path .