JP2004286763A - Ultrasonic transducer and ultrasonic flow measuring instrument - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ultrasonic transducer having uniform characteristics because of its constitution and to improve measuring accuracy of an ultrasonic flowmeter with the resultant coincidence of characteristics of a pair of ultrasonic transducers. <P>SOLUTION: Electrical connection from an electrode surface 13 of a piezoelectric body 11 to an external electrode is performed not by soldering but by using a conductive elastic body 16. The variation of frequency characteristics caused by thermal load to the piezoelectric body 11 can thereby be reduced to obtain the ultrasonic transducer having uniform characteristics, and the measuring accuracy of the ultrasonic flowmeter using the pair of ultrasonic transducers can be improved. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an ultrasonic transducer for transmitting and receiving an ultrasonic pulse, and a measuring device using the ultrasonic transducer.

Conventionally, as shown in FIG. 9, this type of ultrasonic transducer has been electrically connected by soldering a lead wire 41 to an electrode surface 43 of a piezoelectric body 42 (see Patent Document 1). ).
Registered utility model No. 3014801

  However, in the conventional method of electrically connecting ultrasonic transducers, since soldering is performed, (1) deterioration of piezoelectric characteristics due to thermal load, (2) fluctuation of frequency characteristics due to soldering place and amount of solder (3) It had problems such as environmental load due to solder.

  In order to solve the above-mentioned problems, the present invention electrically connects one electrode surface of a piezoelectric body to an external electrode portion using an elastic body made of conductive rubber.

  According to the above invention, since conductive rubber is used for electrical connection, for example, by pressing an elastic body having conductivity, the thermal load is not applied to the piezoelectric body, and the elastic body is softer and more acoustic than solder. Since the impedance is also small, the mechanical load is small and the fluctuation in the characteristics of the piezoelectric body is suppressed, so that the characteristics of the ultrasonic transducer can be made uniform. In particular, in a measuring device such as an ultrasonic flowmeter using a pair of ultrasonic transducers, the characteristics of the pair of ultrasonic transducers can be easily matched, and the measurement accuracy can be improved. Further, since no solder is used, the load on the environment can be reduced.

  According to the present invention, transmission / reception characteristics are improved, and high-precision measurement can be performed by using this ultrasonic transducer in an ultrasonic flow measuring device.

  An embodiment of the present invention is directed to an ultrasonic transducer for transmitting and receiving ultrasonic pulses, comprising a piezoelectric body having electrode surfaces on two opposing surfaces, and a top portion connecting one electrode surface of the piezoelectric body. Having a cylindrical case having, a matching layer provided on a surface facing the piezoelectric body of the top part of the cylindrical case, and a terminal for transmitting an electric signal to the piezoelectric body, A terminal plate connected and fixed to the heavenly cylindrical case, an elastic body made of conductive rubber sandwiched between the other electrode surface of the piezoelectric body and the terminal, and electrically connecting the two; Movement prevention means for preventing the elastic body from moving in the lateral direction, and the elastic body is configured to be elastically attached to the other electrode surface of the piezoelectric body in a surface contact state, so that the frequency characteristic fluctuation due to soldering is provided. And environmental load can be reduced.

  The elastic body is prevented from moving by the movement preventing means. Accordingly, there is no disconnection or the like due to the movement of the elastic body, and the reliability can be improved. Specifically, it is conceivable that the elastic body is located inside the concave portion provided on the terminal plate, or the elastic body is located inside the protrusion provided on the terminal plate.

  The elastic body has a configuration in which insulating portions are arranged so as to surround the periphery of the conductive portion, the conductive portions and the insulating portions are alternately arranged in layers, and if the insulating portion is configured to be located in the outermost layer, electric Insulation can be greatly improved.

  Then, at least one pair of the above-mentioned ultrasonic transducers is arranged in the flow rate measuring part through which the fluid to be measured flows, and the flow velocity and / or flow rate of the fluid to be measured is measured based on the ultrasonic propagation time between these ultrasonic transducers. By doing so, highly accurate measurement of the flow velocity and / or flow rate becomes possible.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, components denoted by the same reference numerals are the same components, and a detailed description thereof will be omitted.

(Embodiment 1)
FIG. 1 is a block diagram showing an ultrasonic flowmeter according to one embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a flow rate measuring unit through which a fluid to be measured flows, 2 and 3 denote ultrasonic transducers that are disposed opposite to the flow measuring unit and transmit and receive ultrasonic waves, and 4 denotes a drive that drives the ultrasonic transducer. 5, a switching circuit for switching the ultrasonic transducer for transmission and reception, 6 a reception detection circuit for detecting the ultrasonic pulse, 7 a timer for measuring the propagation time of the ultrasonic pulse, and 8 for calculating the flow rate from the output of the timer And a control unit 9 for outputting a control signal to the drive circuit and the timer.

  First, the operation and operation will be described. The non-measurement fluid is, for example, LP gas, and the driving frequency of the ultrasonic transducers 2 and 3 is about 500 kHz. The control unit 9 outputs a transmission start signal to the drive unit 4 and at the same time causes the timer 7 to start measuring time. Upon receiving the transmission start signal, the drive unit 4 drives the ultrasonic transducer 3 to transmit an ultrasonic pulse. The transmitted ultrasonic pulse propagates in the flow measurement and is received by the ultrasonic transducer 2. The received ultrasonic pulse is converted into an electric signal by the ultrasonic transducer 2 and output to the reception detection circuit 6. The reception detection circuit 6 determines the reception timing of the reception signal, stops the timer 7, and calculates the propagation time t1 by the calculation unit 8.

  Subsequently, the switching circuit 5 switches the ultrasonic transducers 2 and 3 connected to the drive unit 4 and the reception detection circuit 6, and the control unit 9 outputs a transmission start signal to the drive unit 4 and simultaneously measures the time of the timer 7. Let it start. Contrary to the measurement of the propagation time t1, an ultrasonic pulse is transmitted by the ultrasonic transducer 2 and received by the ultrasonic transducer 3 and the computing time 8 is computed by the computing unit 8.

  Here, the distance connecting the centers of the ultrasonic transducer 2 and the ultrasonic transducer 3 is L, the sound velocity of the LP gas in a windless state is C, the flow velocity in the flow measuring unit 1 is V, Assuming that the angle between the direction of the flow and the line connecting the centers of the ultrasonic transducers 2 and 3 is θ, the propagation times t1 and t2 are represented by (Equation 1) and (Equation 2). When the sound velocity C of the fluid to be measured is eliminated from (Equation 1) and (Equation 2) and the flow velocity V is obtained, (Equation 3) is obtained. Since L is known, the flow velocity V can be obtained by measuring t1 and t2.

t1 = L / C + Vcos θ (1)
t2 = L / C−Vcos θ (2)
V = L / 2 cos θ [(1 / t1) − (1 / t2)] (3)
However, the time difference between t1 and t2 is extremely small when the flow velocity V is slow, and it is difficult to measure accurately. Therefore, generally, the measurement accuracy of the propagation times t1 and t2 is improved by using a method of averaging by repeating the measurement N times or the sing-around method, and the accuracy of the flow velocity V is increased. If the flow velocity V and the area of the flow measurement unit 1 are S and the correction coefficient is K, the flow Q can be calculated by (Equation 4).

Q = KSV (4)
Next, an ultrasonic transducer used for an ultrasonic flowmeter will be described. In order to improve the measurement accuracy of the flow rate in the ultrasonic flowmeter, it is preferable that the pair of ultrasonic transducers have the same characteristics. However, when a method of soldering lead wires, which is a general electrical connection method, is used, the frequency characteristics and the transmission / reception sensitivity of the ultrasonic transducer may be affected by thermal effects and the amount of solder to be attached. Therefore, in order to reduce variations in frequency characteristics and transmission / reception sensitivity, an ultrasonic transducer having the configuration shown in FIG. 2 is used. In FIG. 2, an ultrasonic transducer 10 includes a piezoelectric body 11 having an electrode surface 12 and an electrode surface 13, a matching layer 14, a SUS cylindrical case 15, a conductive elastic body 16, and two It is composed of a terminal plate 19 having terminals 17 and 18. The electrode surface 12 and the electrode surface 13 are square with one side of about 7.6 mm, the matching layer 14 has a diameter of about 11 mm, and the diameter near the top of the case 15 is about 11 mm.

  First, the matching layer 14 and the electrode surface 12 of the piezoelectric body 11 are bonded and fixed to the top of a SUS case 15 having a thickness of 0.2 mm using, for example, an epoxy adhesive. At this time, by reducing the thickness of the adhesive, the electrical connection between the electrode surface 12 and the case 15 can be obtained simultaneously with the adhesive fixing. Next, an elastic body 16 having conductivity (for example, a conductive rubber made of silicon rubber) is sandwiched between the electrode surface 13 of the piezoelectric body 11 and the terminal 17 of the terminal plate 19 and pressurized. And the vicinity 24 of the outer periphery of the case 15 are connected by electric welding. The outer peripheral portion 21 and the central portion 22 of the terminal plate 19 are made of, for example, iron. The outer peripheral portion 21 is provided with the terminal 18, and the central portion 22 is provided with the terminal 17. Electrically insulated. As a result, the electrode surface 13 and the terminal 17 are electrically connected, and the electrode surface 12 is electrically connected to the terminal 18 via the case 15 also serving as an external electrode and the outer peripheral portion 21 of the terminal plate 19.

  In the ultrasonic transducer 10 configured as described above, since no thermal influence or mechanical load is applied to the piezoelectric body 11, the characteristics and dimensions of the piezoelectric body 11, the case 12, and the matching layer 14 can be controlled. In addition, variations in characteristics can be reduced, and a pair of ultrasonic transducers having the same characteristics can be easily obtained. As a result, the measurement accuracy of the ultrasonic flowmeter can be improved. Furthermore, since lead wires are not used, defects due to disconnection can be reduced, and environmental load due to solder can be reduced.

  In the present embodiment, conductive rubber made of silicon rubber is used for the elastic body 16, but other elastic materials such as NBR rubber and liquid crystal polymer may be used as long as they are conductive. Although the non-measuring fluid is LP gas, it may be a gas such as city gas or air or a liquid such as water. Although the frequency of the ultrasonic transducers 2 and 3 is set to 500 kHz, a frequency other than 500 kHz suitable for measurement of a non-measurement fluid may be selected. Although the ultrasonic transducers 2 and 3 are arranged obliquely with respect to the flow direction, they may be arranged in parallel with the flow or at positions where the reflection of the inner wall surface of the flow rate measuring unit 1 is used. It may be arranged. Although the outer peripheral portion 21 and the central portion 22 are electrically insulated by the glass 20, any material other than glass may be used as long as it is an insulator. For example, a resin such as an epoxy resin may be used. Further, although the piezoelectric body 11 is bonded and fixed to the top of the case 15 having a cylindrical shape, the present invention is not limited to the above conditions. The case 15 may have a shape other than the cylindrical shape. It may be arranged on the outer wall surface by bonding or the like. Further, although the case 15 is used in the direction of transmitting and receiving ultrasonic waves, it may be used in the direction opposite to the direction of transmitting and receiving. Although the ultrasonic transducers 2 and 3 are used for the ultrasonic flowmeter, the ultrasonic transducer for flaw detection, the ultrasonic probe for medical treatment, the ultrasonic transducer for distance measurement, and the ultrasonic transducer for underwater use are used. It may be used for a sonic sonar or the like. Further, when the space formed by the case 15 and the terminal plate 19 is replaced with dry nitrogen or an inert gas, oxidation of the electrode surfaces 12 and 13 and deterioration of the elastic body can be prevented, and reliability can be further improved.

(Embodiment 2)
Next, a second embodiment will be described with reference to the drawings. FIG. 3 is a sectional view of the ultrasonic transducer according to the present embodiment. Reference numeral 25 denotes an ultrasonic transducer, which electrically connects the piezoelectric body 11 having the electrode surfaces 12 and 13, the matching layer 14, the case 15, the terminal plate 19 having two terminals 17 and the terminals 18, and the terminals 18 and 17. Glass 20 for electrically insulating the above is the same as the configuration in FIG. The difference from the configuration of FIG. 2 is that the two electrode surfaces 12 and 13 of the piezoelectric body 11 are electrically connected by using the elastic bodies 26 and 27 having conductivity. The operation and operation of the ultrasonic flowmeter are the same as those in the first embodiment, and a description thereof will be omitted.

  An example of a method of assembling an ultrasonic wave receiver 25 using an elastic body 26 having electrical conductivity instead of bonding the electrode surface 12 of the piezoelectric body 11 to the case 15 will be described. First, the matching layer 14 is bonded and fixed to the top of the SUS case 15 having a thickness of 0.2 mm using, for example, an epoxy-based adhesive. Next, an elastic body 26 having conductivity (for example, conductive rubber made of silicon rubber) is arranged inside the case 15, and the electrode surface 12 of the piezoelectric body 11 is arranged to be in contact with the elastic body 26. Next, an elastic body 27 (for example, conductive rubber made of silicon rubber) is arranged so as to be in contact with the electrode surface 13 of the piezoelectric body 11. The elastic body 27 and the terminal center portion 22 of the terminal plate 19 are pressed and pressed. In this state, the periphery 23 of the terminal plate 19 and the periphery 24 of the case 15 are connected by electric welding. The outer peripheral portion 21 and the central portion 22 of the terminal plate 19 are made of, for example, iron. The outer peripheral portion 21 is provided with the terminal 18, and the central portion 22 is provided with the terminal 17. Electrically insulated. As a result, the electrode surface 13 and the terminal 17 are electrically connected, and the electrode surface 12 is electrically connected to the terminal 18 via the case 15 also serving as an external electrode and the outer peripheral portion 21 of the terminal plate 19.

  In the ultrasonic transducer 25 configured as described above, the electrical connection between the electrode surface 12 of the piezoelectric body 11 and the case 15 is not pressure bonding but pressure connection using the elastic body 26 and the elastic body 27. Variations in frequency characteristics and transmission / reception sensitivities due to variations in the thickness of the agent can be reduced, so that more accurate measurement can be performed.

  In this embodiment, conductive rubber made of silicon rubber is used for the elastic body 26 and the elastic body 27. However, other elastic materials such as NBR rubber and liquid crystal polymer may be used as long as the elastic body has conductivity. .

(Embodiment 3)
Embodiment 3 of the present invention will be described with reference to the drawings. FIG. 4 is a sectional view of the ultrasonic transducer according to the present embodiment. Reference numeral 28 denotes an ultrasonic transducer, which is a piezoelectric body 11 having an electrode surface 12 and an electrode surface 13, a matching layer 14, a case 15, and an elastic body 16 having conductivity. . The difference from the configuration of FIG. 2 is that a concave portion 30 is provided in a terminal plate 29 having two terminals 17 and 18 as a means for preventing the elastic body 16 from moving laterally. The operation and operation of the ultrasonic flow meter are the same as in the first embodiment, and a description thereof will be omitted.

  First, the configuration of the terminal plate 29 will be described. The outer peripheral portion 21 and the central portion 22 of the terminal plate 29 are made of, for example, iron, and the thickness of the central portion 22 is smaller than that of the outer peripheral portion 21 so that the concave portion 30 is formed near the center of the terminal plate 29. The outer peripheral portion 21 and the central portion 22 are electrically insulated by the glass 20, and the outer peripheral portion 21 and the glass 20 have substantially the same thickness. The terminal 18 is provided on the outer peripheral portion 21 and the terminal 17 is provided on the central portion 22.

  An example of an assembling method of the ultrasonic transducer 28 using the terminal plate 29 configured as described above will be described. First, the matching layer 14 and the electrode surface 12 of the piezoelectric body 11 are bonded and fixed to the top of a SUS case 15 having a thickness of 0.2 mm using, for example, an epoxy adhesive. At this time, by reducing the thickness of the adhesive, the electrical connection between the electrode surface 12 and the case 15 is performed simultaneously with the adhesive fixing. Next, the elastic body 16 made of conductive rubber is disposed in the concave portion 30 so as to be dropped, and the elastic body 16 is sandwiched between the electrode surface 13 and the central portion 22 and pressurized. The outer periphery 24 of 15 is connected by electric welding.

  In the ultrasonic transducer 28 configured as described above, since the elastic body 16 is prevented from moving in the lateral direction by the concave portion 30, contact failure due to the movement of the elastic body 16 can be prevented. The performance is improved. Further, since the elastic body 16 is disposed so as to be dropped into the concave portion 30 of the terminal plate 29, the elastic body 16 is prevented from moving when the terminal plate 29 is fixed.

  In the present embodiment, the thickness of the outer peripheral portion 21 is made substantially equal to the thickness of the glass 20. However, if the outer peripheral portion 21 and the central portion 22 are not electrically short-circuited by the elastic body 16, it is not necessary to make the thickness approximately equal. Further, although the concave portion 30 is formed by making the thickness of the central portion 22 thinner than the outer peripheral portion 21, a concave portion may be provided in the central portion 22.

(Embodiment 4)
Embodiment 4 of the present invention will be described with reference to the drawings. FIG. 5 is a sectional view of the ultrasonic transducer according to the present embodiment. Reference numeral 31 denotes an ultrasonic transducer, which is a piezoelectric body 11 having an electrode surface 12 and an electrode surface 13, a matching layer 14, a case 15, and an elastic body 16 having conductivity. . The difference from the configuration of FIG. 2 is that a projection 33 is provided on a terminal plate 32 having two terminals 17 and 18 as means for preventing the elastic body 16 from moving in the lateral direction. . The operation and operation of the ultrasonic flow meter are the same as in the first embodiment, and a description thereof will be omitted.

  First, the configuration of the terminal plate 32 will be described. The outer peripheral portion 21 and the central portion 22 of the terminal plate 32 are made of, for example, iron, and the outer peripheral portion 21 and the central portion 22 are electrically insulated by the glass 20 so that the projection 20 is formed on the terminal plate 32. It is thicker than the outer peripheral part 21 and the central part 22. The terminal 18 is provided on the outer peripheral portion 21 and the terminal 17 is provided on the central portion 22.

  An example of an assembling method of the ultrasonic transducer 31 using the terminal plate 32 configured as described above will be described. First, the matching layer 14 and the electrode surface 12 of the piezoelectric body 11 are bonded and fixed to the top of a SUS case 15 having a thickness of 0.2 mm using, for example, an epoxy-based adhesive. At this time, by reducing the thickness of the adhesive, the electrical connection between the electrode surface 12 and the case 15 is performed simultaneously with the adhesive fixing. Next, the elastic body 16 made of conductive rubber is arranged inside the protrusion 33 of the terminal plate 32, and the elastic body 16 is sandwiched between the electrode surface 13 and the center portion 22 and pressed, and in this state, the outer periphery of the terminal plate 32 is pressed. The vicinity 23 and the periphery 24 of the case 15 are connected by electric welding.

  In the ultrasonic wave transmitter / receiver 31 configured as described above, since the elastic body 16 is prevented from moving in the lateral direction by the protrusion 33, it is possible to prevent a contact failure due to the movement of the elastic body 16. Reliability is improved. Furthermore, since the elastic body 16 is disposed so as to be dropped into the projection 33 of the terminal plate 32, the elastic body 16 is prevented from moving when the terminal plate 32 is fixed, so that the assembly is facilitated.

  Although the projections 33 are formed on the glass 20 in the present embodiment, the projections may be provided on the outer periphery of the central portion 22 to insulate the central portion 22 and the outer peripheral portion 21.

(Embodiment 5)
Embodiment 5 of the present invention will be described with reference to the drawings. FIG. 6 is a cross-sectional view of the ultrasonic transducer according to the present embodiment. Numeral 34 denotes an ultrasonic transducer, which is a piezoelectric body 11 having an electrode surface 12 and an electrode surface 13, a matching layer 14, a case 15, a terminal plate 19 having two terminals 17 and terminals 18, and the above is the configuration of FIG. Is similar to The difference from the configuration of FIG. 2 is that a conductive portion 36 and an insulating portion 37 are provided on an elastic body 35 having conductivity. The operation and operation of the ultrasonic flow meter are the same as in the first embodiment, and a description thereof will be omitted.

  First, the configuration of the conductive elastic body 35 will be described with reference to the drawings. FIG. 7 is a cross-sectional view of the elastic body 35 having conductivity. The conductive portion 36 is made of, for example, silicon rubber having conductivity, and an insulating portion 37 made of, for example, silicon rubber having insulating properties is arranged so as to surround the periphery of the conductive portion 36.

  An example of an assembling method of the ultrasonic transducer 34 using the elastic body 35 configured as described above will be described. First, the matching layer 14 and the electrode surface 12 of the piezoelectric body 11 are bonded and fixed to the top of a SUS case 15 having a thickness of 0.2 mm using, for example, an epoxy adhesive. At this time, by reducing the thickness of the adhesive, the electrical connection between the electrode surface 12 and the case 15 is performed simultaneously with the adhesive fixing. Next, an elastic body 35 having conductivity is sandwiched between the electrode surface 13 of the piezoelectric body 11 and the center portion 22 of the terminal plate 19 and pressurized. In this state, the outer periphery 23 of the terminal plate 19 and the outer periphery 24 of the case 15 are electrically connected. Connect by welding. The outer peripheral portion 21 and the central portion 22 of the terminal plate 19 are made of, for example, iron. The outer peripheral portion 21 is provided with the terminal 18, and the central portion 22 is provided with the terminal 17. Electrically insulated. As a result, the electrode surface 13 and the terminal 17 are electrically connected, and the electrode surface 12 is electrically connected to the terminal 18 via the case 15 also serving as an external electrode and the outer peripheral portion 21 of the terminal plate 19.

  In the ultrasonic transducer 34 configured as described above, since the insulating portion 37 is provided near the outer periphery of the elastic body 35 used for electrical connection, even if the position of the elastic body 35 is shifted in the assembly process. Since it is possible to prevent the two external electrodes from being electrically short-circuited, it is possible to reduce defects due to the electric short-circuit and to facilitate the assembly. Further, reliability is improved.

  In the present embodiment, the conductive portion 36 is made of a conductive rubber made of silicon-based rubber in the present embodiment, but any other elastic material such as NBR rubber or liquid crystal polymer may be used as long as it is a conductive elastic body. Further, the insulating portion 37 is made of silicon rubber having an insulating property, but other insulating materials may be used. Further, the configuration of the conductive elastic body 35 is such that the periphery of the conductive part 36 is surrounded by the insulating part 37. However, as shown in the elastic body 38 of FIG. 8, the conductive layer 39 and the insulating layer 40 are formed in layers. The elasticity may be maintained by alternately arranging them. Further, as shown in FIG. 8, if the outermost layer of the elastic body 38 is the insulating layer 39, the two external electrodes can be prevented from being electrically short-circuited even if the thickness of the glass 20 is smaller than the thickness of the outer peripheral portion 21. .

  Further, in the first to fifth embodiments, the matching layer 14 is disposed in the case 15, but it is not necessary to provide the matching layer 14 depending on the non-measuring fluid. Although the case 15 is made of SUS, the case 15 may be made of a metal other than SUS, such as iron, aluminum, brass, or copper, or may be a resin such as epoxy having electrodes provided on the surface. Although the outer peripheral portion 21 and the central portion 22 of the terminal plate are made of iron, they may be made of metal other than iron, such as SUS, aluminum, brass, or copper, or may be made of resin such as epoxy having electrodes on the surface. Further, although the outer periphery 23 of the terminal plate and the outer periphery 24 of the case are electrically welded, welding other than electric welding or bonding may be used.

  As is clear from the above description, the following effects can be obtained.

  (1) An ultrasonic transducer for transmitting and receiving ultrasonic pulses, comprising: a piezoelectric body having electrode surfaces on two opposing surfaces; and an external electrode unit for transmitting an electric signal to the piezoelectric body. The one electrode surface and the external electrode portion are electrically connected using an elastic body made of conductive rubber, so that no thermal load due to solder is applied, so that the frequency characteristics match, and the environmental load is further reduced. A pair of ultrasonic transducers can be obtained.

  (2) Two external electrode portions are provided, and one electrode surface of the piezoelectric body is electrically connected to one of the external electrode portions using an elastic body made of conductive rubber, and the other electrode surface of the piezoelectric body is provided. And the other external electrode portion are electrically connected by bonding, so that a thermal load due to solder is not applied, so that the frequency characteristics match, and furthermore, it is possible to obtain a pair of ultrasonic transducers with reduced environmental load. it can.

  (3) Since two external electrode portions are provided, and each of the electrode surfaces of the piezoelectric body and each of the external electrode portions are electrically connected by using a conductive rubber, an environmental load due to solder is reduced, and further, adhesion is achieved. Fluctuations in frequency characteristics and transmission / reception sensitivity due to variations in the thickness of the agent are reduced, so that an ultrasonic transducer capable of high-accuracy measurement can be obtained.

  (4) Since the electrode surface of the piezoelectric body and the external electrode portion are electrically connected to each other by pressing with a conductive rubber therebetween, a thermal load due to solder is not applied, so that fluctuations in frequency characteristics can be reduced and assembly is easy. A simple ultrasonic transducer can be obtained.

  (5) A terminal plate having two terminals that are electrically separated is provided, and the two terminals are electrically connected to respective external electrode portions. Therefore, connection to an external device using a lead wire is easy. An ultrasonic transducer can be obtained.

  (6) Since the terminal plate is provided with a movement preventing means for preventing the conductive rubber from moving in the lateral direction, disconnection due to the movement of the conductive rubber can be prevented, so that a highly reliable ultrasonic transducer is provided. Can be obtained.

  (7) The movement preventing means is a concave portion provided in the terminal plate. Since the conductive rubber and one external electrode portion are provided inside the concave portion, the conductive rubber is disposed so as to drop the conductive rubber into the concave portion. This can prevent poor contact due to the lateral movement of the antenna, so that a highly reliable ultrasonic transducer can be obtained. Further, since the movement of the conductive rubber is prevented, an ultrasonic transducer that can be easily assembled can be obtained.

  (8) The movement preventing means is a protrusion provided on the terminal plate. Since the conductive rubber and one of the external electrode portions are provided inside the protrusion, the protrusion is arranged so as to prevent the conductive rubber from moving. By doing so, it is possible to prevent poor contact due to the lateral movement of the conductive rubber, so that a highly reliable ultrasonic transducer can be obtained. Further, since the movement of the conductive rubber is prevented, an ultrasonic transducer that can be easily assembled can be obtained.

  (9) It is possible to obtain a highly reliable ultrasonic transducer in which an insulating portion having an insulating property with the conductive rubber is provided and two external electrodes are prevented from being electrically short-circuited by the insulating portion. it can.

  (10) Since the conductive rubber and the insulating portion are alternately arranged in layers and the outermost layers on both sides are insulating layers, an electrical connection is made to prevent two external electrodes from being electrically short-circuited by the insulating portion. Since a failure due to a short circuit can be prevented, a highly reliable ultrasonic transducer that is easy to assemble can be obtained.

  (11) Since at least one external electrode portion has a bend, the degree of freedom in fixing the external electrode is improved, and an ultrasonic transducer that can be easily assembled with the ultrasonic transducer can be obtained.

  (12) In an ultrasonic transducer for transmitting and receiving ultrasonic pulses, a piezoelectric body having two pairs of electrode surfaces, a heavenly cylindrical case, and an external electrode unit for transmitting an electric signal to the piezoelectric body And bonding one electrode surface of a piezoelectric body to a top portion of the cylindrical case, and electrically connecting the other electrode surface of the piezoelectric body to the external electrode portion using conductive rubber. Is what you do.

  (13) A flow rate measurement unit through which the fluid to be measured flows, a pair of ultrasonic transducers according to any one of Embodiments 1 to 12 provided in the flow rate measurement unit, and one of the ultrasonic transducers A driving unit, and a reception detection unit connected to the other ultrasonic transducer for detecting an ultrasonic pulse, and a calculation unit for measuring the propagation time of the ultrasonic pulse and calculating the flow rate, so that a pair of The characteristics of the ultrasonic transducer can be easily matched, and an ultrasonic flowmeter with high measurement accuracy can be obtained.

  INDUSTRIAL APPLICABILITY The present invention has improved transmission / reception characteristics and is useful for an ultrasonic flow measurement device and the like.

1 is a block diagram illustrating an ultrasonic flowmeter according to an embodiment of the present invention. (A) External view of ultrasonic transducer in one embodiment of the present invention (b) Cross-sectional view of ultrasonic transducer in one embodiment of the present invention Sectional view of an ultrasonic transducer according to an embodiment of the present invention. Sectional view of an ultrasonic transducer according to an embodiment of the present invention. Sectional view of an ultrasonic transducer according to an embodiment of the present invention. Sectional view of an ultrasonic transducer according to an embodiment of the present invention. Sectional view of an elastic body having conductivity according to an embodiment of the present invention. Sectional drawing of the modification of the ultrasonic transducer in one Embodiment of this invention Cross section of conventional ultrasonic transducer

Explanation of reference numerals

DESCRIPTION OF SYMBOLS 1 Flow rate measurement part 2, 3 Ultrasonic transducer 4 Drive part 10 Ultrasonic transducer 11 Piezoelectric body 12, 13 Piezoelectric electrode surface 14 Matching layer 15 Case 16 Elastic body 17, 18 Terminal 19 Terminal board 25 Ultrasonic transmission and reception Wavers 26, 27 Elastic body 28 Ultrasonic transducer 29 Terminal plate 31 Ultrasonic transducer 32 Terminal board 34 Ultrasonic transducer 35 Elastic body 36 Conductive part 37 Insulating part 38 Elastic body 39 Conductive layer 40 Insulating layer 42 Piezoelectric body 43 Electrode surface

Claims (6)

In an ultrasonic transducer for transmitting and receiving ultrasonic pulses, a piezoelectric body having an electrode surface on two opposing surfaces, and a topped cylindrical case having a ceiling connecting one electrode surface of the piezoelectric body, A matching layer provided on a surface of the top of the cylindrical case opposite to the piezoelectric body, and a terminal for transmitting an electric signal to the piezoelectric body, and connected and fixed to the cylindrical case; And the elastic body made of conductive rubber, which is sandwiched between the other electrode surface of the piezoelectric body and the terminal, and electrically connects them, and the elastic body moves in the lateral direction. An ultrasonic transmitter / receiver, comprising: a movement preventing unit for preventing the elastic body from elastically adhering to the other electrode surface of the piezoelectric body in a surface contact state. The ultrasonic transducer according to claim 1, wherein the movement preventing means is a concave portion provided in the terminal plate, and the elastic body is located inside the concave portion. The ultrasonic transducer according to claim 1, wherein the movement preventing means is a protrusion provided on the terminal plate, and the elastic body is located inside the protrusion. The ultrasonic transducer according to claim 2, wherein the elastic body is configured by arranging an insulating part so as to surround a periphery of the conductive part. The ultrasonic transmission / reception wave according to any one of claims 2 to 4, wherein the elastic body is configured by alternately arranging conductive portions and insulating portions in a layered manner, and is set such that the insulating portion is located in the outermost peripheral layer. vessel. At least one pair of the ultrasonic transducer according to any one of claims 1 to 5 is arranged in a flow rate measurement unit through which a fluid to be measured flows, and the ultrasonic transducer is measured based on an ultrasonic propagation time between the ultrasonic transducers. An ultrasonic flow measurement device that measures the flow velocity and / or flow rate of a fluid.

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