JP2010181355A - Ultrasonic transducer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To stabilize characteristics of an ultrasonic transducer and to stabilize measurement of a measured fluid. <P>SOLUTION: An acoustic aligner 5, a piezoelectric material 4 and an electrode lead 6 electrically connected with electrodes 2 and 3 of the piezoelectric material 4 are covered with an insulator 11. Thus, the insulator is covered between the electrodes, if the ultrasonic transducer is subjected to dew condensation caused by a rapid change in temperature or rain water such as rain drops, thereby ultrasonic waves can stably be transmitted and received, and a flow speed and/or a flow rate of the measured fluid can stably be measured. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an ultrasonic transducer for transmitting and receiving ultrasonic waves via a fluid such as gas.

  As shown in FIG. 9, the conventional ultrasonic transducer 41 is configured by joining an acoustic matching body 44 to a piezoelectric body 43 having electrodes 42 on both sides, and electrode leads 45 are connected to the electrodes 42. Joined by welding, soldering, etc.

  Therefore, the electrode leads 45 between the electrodes 42 or joined to these electrodes 42 are exposed to the atmosphere.

  In addition, the ultrasonic transducer 46 shown in FIG. 10 has a piezoelectric member 49 bonded to the inner surface of the top wall of the cylindrical metal case 47 via a bonding means 48 such as an adhesive, and an adhesive or the like bonded to the outer surface of the top wall. The acoustic matching bodies 51 are fixed through the means 50, respectively.

  A conductive terminal plate 52 is joined to the open side of the metal case 47 by welding. The terminal plate 52 includes electrode terminals 53, 54. One electrode terminal 53 is connected to one electrode 55 of the piezoelectric body 49 via the terminal plate 52 and the metal case 47, and one electrode terminal 54 is an insulating material 56. Insulated, penetrates through the terminal plate 52, and is connected to the other electrode 57 of the piezoelectric body 49.

  An electrical signal is transmitted to the electrodes 55 and 57 via the electrode terminals 53 and 54, and the piezoelectric body 49 converts the electrical signal into vibration, and the generated vibration is efficiently transmitted to the fluid to be measured through the acoustic matching body 51. To do.

The electrode terminals 53 and 54 and the electrode leads joined thereto are electrically exposed to the atmosphere (see, for example, Patent Documents 1 and 2).
JP 2006-217002 A Japanese Patent Laid-Open No. 2003-111195

  However, in the above-described conventional configuration, the ultrasonic transducer may come into contact with rainwater due to condensation, rain, or the like due to a rapid temperature change, thereby leaking current and making stable measurement impossible. It was.

  In other words, the electrode terminal and the electrode lead are electrically bonded for the purpose of driving the ultrasonic transducer and transmitting the obtained signal to the measurement circuit. Depending on the bonding method, whiskers grow from the plated portion of the electrode lead. However, a stable flow rate measurement becomes impossible due to leakage of current between electrodes or terminals.

  The present invention solves the above-described conventional problems, and an object of the present invention is to provide an ultrasonic transducer that can stably measure a fluid to be measured.

In order to solve the above-described problems, the present invention includes an acoustic matching body, a piezoelectric body, and an electrode lead electrically connected to an electrode of the piezoelectric body covered with an insulator.

  With the above-described configuration, the electrodes are not in electrical contact with rainwater due to condensation, rainfall, or the like due to a rapid temperature change, and the current to be measured can be stably measured without leaking current.

  According to the present invention, since a stable ultrasonic transducer can be obtained, the fluid to be measured can be stably measured.

  In the first invention, an acoustic matching body, a piezoelectric body, and an electrode lead electrically connected to the electrode of the piezoelectric body are covered with an insulator.

  As a result, rapid temperature changes when measuring the fluid to be measured, current leakage due to moisture adhering between the electrode and electrode lead due to rain, etc., and current leakage due to whisker between electrode leads do not occur, so stable measurement be able to.

  The second invention is composed of an acoustic matching body, a piezoelectric body, and an electrode lead electrically connected to the electrode of the piezoelectric body, and one electrode of the piezoelectric body exposed to the space, and a conductive portion of the electrode lead Is covered with an insulator, so that there is no immediate temperature change of the measured fluid meter, no current leakage due to moisture adhering between the electrode and the electrode lead due to rainfall, etc., and no current leakage due to the whisker between the electrode leads. Stable measurement can be performed.

  A third invention includes an acoustic matching body, a piezoelectric body, and an electrode lead electrically connected to an electrode of the piezoelectric body, and at least one electrode of the piezoelectric body exposed to the space, and electrode lead conduction By covering the part with an insulator, there is no immediate temperature change of the fluid meter to be measured, current leakage due to moisture adhering between the electrode and electrode lead due to rain, etc., and current leakage due to whisker between the electrode leads Stable measurement can be performed.

  According to a fourth aspect of the present invention, in particular, in one of the first to third aspects of the present invention, the piezoelectric member is disposed on the inner surface of the metal case and the acoustic matching member is disposed on the outer surface, so that the measured fluid is measured. It is possible to perform stable measurement without causing current leakage due to moisture between the electrodes and electrode leads due to sudden temperature changes, rainfall, etc., and current leakage due to whiskers between the electrode leads. Since the electrode is disposed in the case, corrosion and alteration of the electrode are suppressed, and measurement with excellent reliability can be performed.

  In a fifth aspect of the present invention, one ultrasonic transducer according to the first to fourth aspects of the present invention is disposed upstream and downstream of the flow path through which the fluid to be measured flows, and the ultrasonic propagation time between these ultrasonic transducers The ultrasonic flow measuring device that calculates the flow velocity and / or flow rate of the fluid to be measured based on the above can stably measure the flow velocity and flow rate.

  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)
In FIG. 1, an ultrasonic transducer 1 is configured by joining a piezoelectric body 4 having electrodes 2 and 3 on the upper and lower sides and an acoustic matching body 5 with an adhesive.

The electrodes 2 and 3 are formed by heating and baking a conductive paste such as silver or gold, and are electrically joined to the electrode lead 6 by resistance welding, solder, silver brazing, or the like.

  The electrode lead 6 includes an electrode lead conductive portion 7 and an electrode lead insulating portion 8, and is divided into a conductive portion 9 exposed to the space and an insulating portion 10 covered with the electrode lead insulating portion 8.

  When the conductive part 9 exposed to the space or the electrodes 2 and 3 of the piezoelectric body 4 touches water containing impurities, such as rain water or condensed water containing impurities that are condensed due to a sudden temperature change. As a result of current leakage, the expected ultrasonic wave is not radiated to the fluid to be tested with respect to the electrical signal applied to the piezoelectric body 4, so that accurate measurement of the flow rate is impossible.

  For this reason, the entire outer circumference of the ultrasonic transducer 1 including the electrode lead 6 is covered with the insulator 11.

  The insulator 11 can be formed by, for example, CVD deposition of poly-monochloroparaxylylene or polyparaxylylene. The film thickness of parylene is about 5 μm, and the ultrasonic transducer 1 can be coated without a gap.

  Hereinafter, the acoustic matching body 5 will be described.

  The acoustic matching body 5 is filled, for example, by oscillating a hollow glass filler in a fixed container coated with fluorine, and impregnating the container with an epoxy resin mixed with a curing agent, and putting them together with a jig. Heat in an oven.

  The heating conditions are, for example, 150 ° C. and 1 hour. The cured molded body is extracted from the jig, sliced, and bonded to the piezoelectric body 4 so that the sliced acoustic matching body 5 is cleaned with ultrasonic waves.

  By joining the acoustic matching body 5 with an adhesive, the ultrasonic transducer 1 of the first embodiment can be obtained.

  With the above-described configuration, there is no current leakage due to a rapid temperature change at the time of measuring the fluid to be measured, moisture due to adhesion between the electrodes 2 and 3 and the electrode lead 6 due to rain, and current leakage due to a whisker between the electrode leads 6. Therefore, stable flow rate measurement can be performed.

(Embodiment 2)
FIG. 2 shows the second embodiment, and the same reference numerals are given to the components that perform the same operations as those in FIG. 1 for the sake of convenience.

  The insulator 11 fills the space existing between the one electrode 2 in the piezoelectric body 4 and the electrode lead conductive portion 9 exposed to the space and the other electrode 3.

  This insulator is formed, for example, by applying and forming a photo-curable epoxy resin that is cured by ultraviolet light with a dispenser and then curing with an ultraviolet lamp. The insulator 11 can be realized even if it is a thermosetting resin, and is not particularly limited.

  With the above-described configuration, there is no current leakage due to a rapid temperature change at the time of measuring the fluid to be measured, moisture due to adhesion between the electrodes 2 and 3 and the electrode lead 6 due to rain, and current leakage due to a whisker between the electrode leads 6. Therefore, the flow rate can be measured stably.

(Embodiment 3)
FIG. 3 shows Embodiment 3, and the same code | symbol is attached | subjected for convenience to the component which performs the same effect | action as FIG. 1, and the thing of Embodiment 1 is used for concrete description.

  In the piezoelectric body 4, a space existing between one electrode 2 and the electrode lead conductive portion 9 exposed to the space and the other electrode 3 is filled with an insulator 11.

  This insulator can be formed, for example, by applying and forming a photo-curable epoxy resin that is cured by ultraviolet light with a dispenser and then curing with an ultraviolet lamp. The insulator 11 can be realized even if it is a thermosetting resin, and is not particularly limited.

  With the above-described configuration, there is no current leakage due to a rapid temperature change at the time of measuring the fluid to be measured, moisture due to adhesion between the electrodes 2 and 3 and the electrode lead 6 due to rain, and current leakage due to a whisker between the electrode leads 6. Therefore, the flow rate can be measured stably.

(Embodiment 4)
FIG. 4 shows the fourth embodiment.

  In other words, the ultrasonic transducer 21 of the present embodiment has a dome-shaped metal case 22.

  A piezoelectric body 24 is tightly bonded to the inner surface of the top wall of the metal case 22 via a bonding means 23 made of an adhesive, and an acoustic matching body 26 is bonded to the outer surface of the top wall via a bonding means 25.

  The metal case 22 and the metallic terminal plate 27 that closes the lower open portion thereof are electrically joined by welding.

  The terminal plate 27 includes electrode terminals 28 and 29, one electrode terminal 28 is electrically connected to the terminal plate 27, and the other electrode terminal 29 penetrates the terminal plate 27 in an insulating manner through an insulating member 30, The conductive member 31 is connected to the electrode 32 below the piezoelectric body 24.

  One electrode terminal 28 is connected to the electrode 33 above the piezoelectric body 24 via the terminal plate 27 and the metal case 22.

  When an electrical signal is transmitted to the electrodes 32 and 33 of the piezoelectric body 24 via the electrode terminals 28 and 29, the piezoelectric body 24 converts the electrical signal into vibration, and this vibration then passes through the acoustic matching body 26. It efficiently transmits to the fluid to be measured.

  The piezoelectric body 24 is located in a sealed space 34 surrounded by the metal case 22 and the terminal plate 27, and the electrodes 32 and 33 are formed by filling the sealed space with nitrogen or argon gas, which are inert gases. An ultrasonic transducer that does not corrode and has little secular change can be obtained.

  Here, the outer surface of the ultrasonic transducer 21, that is, the upper and outer circumferences of the acoustic matching body 26, the outer circumference and the lower surface of the metal case 22, and the terminal plate 27, and the ultrasonic transducer 1 including the electrode lead 6. The entire outer periphery is covered with the insulator 11.

  Since the electrode lead 6 has the same configuration as that shown in FIG. 1, the same reference numerals are given, and the specific description of the first embodiment is referred to.

  FIG. 5 shows a manufacturing process of the ultrasonic transducer 21 in the present embodiment.

  (A) shows the acoustic matching body 26 produced by the method described in the first embodiment, and (b) shows a metal body formed by applying a thermosetting adhesive used as the joining means 23 to the piezoelectric body 24, and forming a metal. Similarly, the joining means 25 is applied to the upper surface of the top wall of the case 22.

  In (c), the piezoelectric body 24 and the acoustic matching body 26 are bonded and fixed to the metal case 22. At this time, the thermosetting adhesive used as the joining means 23 and 25 is cured in a state where a pressure of about 1 to 10 kg / cm 2 is applied to the piezoelectric body 24, the metal case 22, and the acoustic matching body 26. Heat.

  The semi-finished product 35 that has been heat-cured and joined by the above steps is formed. The metal case 22 provided in the semi-finished product 35 and the terminal plate 27 into which the conductive means 31 are inserted are electrically joined by welding as shown in (d).

  At the time of this welding, argon gas, nitrogen gas, helium gas, or the like, which is an inert gas, is sealed in the sealed space 34 to degrade the electricity 32 and 33 in the piezoelectric body 24 and the joined portion between the piezoelectric body 24 and the metal case 22. It plays a role in reducing.

  The metal case 22 may be iron, brass, copper, aluminum, stainless steel, or an alloy thereof, or a conductive material with a plated surface.

  The thermosetting adhesive used as the joining means 23 and 25 is not particularly limited as long as it is a thermosetting resin such as an epoxy resin, a phenol resin, a polyester resin, or a melamine resin.

  Depending on the case, even if it is a thermoplastic resin, if a glass point transfer is 70 degrees C or less which is high temperature use temperature, it can be used as an adhesive agent.

  (E) has shown the state which joined the electrode lead 6, and the joining method is realizable by welding, silver brazing, soldering etc., for example.

  (F) has shown the state which coded the insulator 11 on the outer periphery.

  With the above-described configuration, since the piezoelectric body 24 is disposed in the sealed space, the ultrasonic transducer 21 having stable characteristics is obtained without being affected by humidity, temperature, contaminants, and the like in the measurement environment. The flow rate of fluid can be measured stably.

(Embodiment 5)
FIG. 6 shows a fifth embodiment, and the same reference numerals are given to components that perform the same operations as those in FIG.

  That is, the exposed two electrode lead conductive portions 9 are filled with the insulator 11.

  The insulator 11 can be formed, for example, by applying and forming a photo-curable epoxy resin that is cured by ultraviolet light with a dispenser and then curing with an ultraviolet lamp.

  The insulator 11 to be filled can be realized even if it is a thermosetting resin, and is not particularly limited.

With the above configuration, flow measurement is stable because there is no immediate temperature change in the fluid meter to be measured, current leakage due to moisture adhering between the electrode and electrode leads due to rainfall, etc., and current leakage due to whiskers between the electrode leads. It can be performed.

(Embodiment 6)
FIG. 7 shows a sixth embodiment, and the same reference numerals are given to components performing the same operations as those in FIG.

  In other words, in the present embodiment, one exposed electrode lead conductive portion 9 is filled with the insulator 11.

  This insulator can be formed, for example, by applying and forming a photo-curable epoxy resin that is cured by ultraviolet light with a dispenser and then curing with an ultraviolet lamp.

  The insulator 11 to be filled can be realized even if it is a thermosetting resin, and is not particularly limited.

  With the above configuration, flow rate measurement is stable because there is no immediate temperature change in the fluid meter to be measured, no current leakage due to moisture adhering between the electrodes and electrode leads due to rain, etc., and no current leakage due to whiskers between the electrode leads. It can be performed.

(Embodiment 7)
FIG. 8 shows an ultrasonic flow measuring apparatus according to the seventh embodiment.

  In FIG. 8, a pair of the ultrasonic transducers 37 shown in the first to sixth embodiments are arranged on the upstream and downstream sides of the flow path 36 through which the fluid flows, and the ultrasonic waves cross obliquely in the flow. is there.

  L1 shows the propagation path of the ultrasonic wave propagating from the ultrasonic transducer 37 arranged on the upstream side, and L2 shows the propagation path of the ultrasonic wave of the ultrasonic transducer 37 arranged on the downstream side. Yes.

  Let V be the flow velocity of the fluid flowing through the flow path 36, C be the velocity of ultrasonic waves in the fluid, and θ be the angle between the direction of fluid flow and the ultrasonic wave propagation direction.

When the upstream ultrasonic transducer 37 is used as an ultrasonic transmitter and the downstream ultrasonic transducer 37 is used as an ultrasonic receiver, the ultrasonic propagation time t1 is:
t1 = L / (C + V cos θ) (1)
And
Next, when the downstream ultrasonic transducer 37 is used as an ultrasonic transmitter and the upstream ultrasonic transducer 37 is used as an ultrasonic receiver, the ultrasonic propagation time t2 is:
t2 = L / (C−Vcos θ) (2)
Indicated by

And if the sound velocity C of the fluid is deleted from the equations (1) and (2),
V = L / 2 cos θ (1 / t1-1 / t2) (3)
The following equation is obtained.

  If L and θ are known, the flow velocity V can be obtained by measuring t1 and t2 with the timing device 38.

  If necessary, the flow rate Q can be obtained by multiplying the flow velocity V by the cross-sectional area S and the correction coefficient K of the flow rate measuring unit 36.

  The calculating means 39 calculates Q = KSV.

  As described above, in the present embodiment, the flow velocity and / or flow rate of the fluid to be measured can be stably measured.

  As described above, since the ultrasonic transducer according to the present invention enables stable flow measurement, not only household flowmeters and industrial flowmeters but also ultrasonic waves are generated in the air to reduce the distance. Applicable to applications such as back sonar for automobiles to be measured.

Sectional drawing of the ultrasonic transducer in Embodiment 1 of this invention Sectional drawing of the ultrasonic transducer in Embodiment 2 of this invention Sectional drawing of the ultrasonic transducer in Embodiment 3 of this invention Sectional drawing of the ultrasonic transducer in Embodiment 4 of this invention Manufacturing process flow diagram of ultrasonic transducer in the fourth embodiment Sectional drawing of the ultrasonic transducer in Embodiment 5 of this invention Sectional drawing of the ultrasonic transducer in Embodiment 6 of this invention Principle of ultrasonic flow measurement device Cross-sectional view of a conventional ultrasonic transducer Cross-sectional view of an ultrasonic transducer showing another example of a conventional ultrasonic transducer

DESCRIPTION OF SYMBOLS 1,21 Ultrasonic transducer 2,3,32,33 Electrode 4,24 Piezoelectric body 5,26 Acoustic matching body 6 Electrode lead 11 Insulator 22 Metal case 36 Flow path

Claims (5)

An ultrasonic transducer in which an acoustic matching body, a piezoelectric body, and electrode leads electrically connected to electrodes of the piezoelectric body are covered with an insulator. Consists of an acoustic matching body, a piezoelectric body, and an electrode lead electrically connected to the electrode of the piezoelectric body, and covers one electrode of the piezoelectric body exposed to the space and the conductive portion of the electrode lead with an insulator Ultrasonic transducer. An acoustic matching body, a piezoelectric body, and an electrode lead electrically connected to the electrode portion of the piezoelectric body, and at least one electrode of the piezoelectric body exposed to the space and the electrode lead conductive portion are covered with an insulator. Ultrasonic transducer. The ultrasonic transducer according to any one of claims 1 to 3, wherein a piezoelectric body is disposed on an inner surface of the metal case and an acoustic matching body is disposed on an outer surface thereof. The ultrasonic transducer according to any one of claims 1 to 4 is arranged on the upstream and downstream sides of the flow path through which the fluid to be measured flows, and based on the ultrasonic propagation time between the ultrasonic transducers, An ultrasonic flow measurement device that calculates the flow velocity and / or flow rate of a measurement fluid.

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