JP2000059891

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DESCRIPTION JP2000059891
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an
aperture type ultrasonic transducer.
[0002]
2. Description of the Related Art As shown in FIG. 3, the general structure of an aperture type
ultrasonic transducer using a bimorph oscillator is a bimorph oscillator 3 in which a piezoelectric
body 2 is bonded to a metal plate 1. Is attached to the upper end of the circumferential convex
portion formed on the upper surface of the terminal plate 4 through the elastic adhesive 14, and
the electrode terminals 5 and 6 of the terminal plate 4 are respectively made into the metal plate
1 and the electrodes of the piezoelectric body 2 The additional vibrators 7 are electrically
connected, attached to the metal plate 1 of the bimorph vibrator 3 and covered with a stopper 10
and a case 11 attached to the terminal plate 4. In addition, the case top surface opening for
transmitting and receiving ultrasonic waves is generally formed of, for example, a metal mesh 16
of brass, aluminum or the like with an opening of 30 to 50 mesh. In addition, as shown in FIG. 4,
the general structure of an aperture type ultrasonic transducer when the material of the case is a
resin molded product is a bimorph oscillator 3 in which a piezoelectric body 2 is bonded to a
metal plate 1 as shown in FIG. , Attached to the upper end of the circumferential convex portion
formed on the terminal plate 4 through the elastic adhesive 14, and the electrode terminals 5
and 6 of the terminal plate 4 to the metal plate 1 and the electrodes of the piezoelectric body 2
respectively. The additional vibrators 7 are attached to the metal plate 1 of the bimorph vibrator
3 and connected with a case 17 attached to the terminal plate 4. The case top surface opening
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for transmitting and receiving ultrasonic waves is generally formed of a resin molded product
having a hole ratio of 40 to 70% having a hole integrally formed with the case side wall. By the
way, when the conventional aperture type ultrasonic transducer is used in a combustible gas
such as methane gas or propane gas, the case of transmitting and receiving ultrasonic waves of
the conventional aperture type ultrasonic transducer is used. The face opening is an electrode
face on the opposing top face of the piezoelectric body 2 because the face opening is a brass of
30 to 50 mesh, a wire mesh such as aluminum, or a resin molded article having an opening ratio
of 40 to 70%. If a fire occurs and a flame occurs inside the case, the combustion flame generated
inside this case passes through the top opening of the case and may be transmitted to the
combustible gas outside the case to cause an explosion. is there.
[0003]
Since the above-mentioned conventional ultrasonic transducer does not have the explosion proof
performance, it can be used, for example, as a combustible gas such as methane gas or propane
gas for applications such as a gas flowmeter. When used in, there is a risk of explosion as
described above, causing inconvenience. The present invention has been made in view of these
problems, and it is an object of the present invention to provide an aperture type ultrasonic
transducer having explosion proof performance that can be used in a flammable gas.
[0004]
SUMMARY OF THE INVENTION In the ultrasonic transducer according to the present invention,
an additional vibrator is attached to a bimorph vibrator in which a metal plate and a piezoelectric
body are bonded, and these are mounted in a case. In the stored configuration, the top surface
opening for transmitting and receiving ultrasonic waves is made of stainless steel SUS316 in a
wire mesh structure in which two or more sheets are overlapped, and that each wire mesh has an
opening of 100 mesh or more. It is characterized.
[0005]
BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be
described below with reference to the drawings.
FIG. 1 is a longitudinal sectional view of a schematic structure of an ultrasonic transducer
showing an embodiment of the present invention, and FIG. 2 is a longitudinal sectional view of a
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schematic structure of an ultrasonic transducer showing another embodiment of the present
invention. is there. In FIG. 1 and FIG. 2, parts that are the same as in FIG. 3 and FIG. 4 showing
the longitudinal cross-sectional view of the schematic structure of the conventional ultrasonic
transducer are given the same reference numerals. In FIG. 1, an adhesive (not shown) or the like
is attached to a flat plate-like metal plate 1 similar to the flat plate-like piezoelectric body 2 in
which electrodes (not shown) are formed on the main surfaces facing each other. Together, the
bimorph oscillator 3 is configured. The bimorph vibrator 3 is attached to the upper end of the
circumferential convex portion formed on the upper surface of the terminal plate 4 which is an
insulator via an elastic adhesive 14 such as silicon, and the electrode terminals 5 and 6 of the
terminal plate 4 are attached. Are electrically connected to the electrodes of the metal plate 1
and the piezoelectric body 2 respectively, and the additional vibrator 7 is provided at
substantially the center of the metal plate 1 of the bimorph oscillator 3 via an adhesive (not
shown) such as epoxy. These are attached and formed by covering them with a stopper 10 made
of metal such as aluminum attached to the terminal plate 4 and a case 11. The case top surface
opening for transmitting and receiving ultrasonic waves has a double mesh structure of a
stainless steel SUS316 mesh 12 and 13 having an opening of 100 mesh or more. The stopper 10
and the case 11 may be made of resin or the like instead of metal. Further, the stainless steel
SUS316 wire mesh in the case top surface opening is not limited to the double structure, and it is
sufficient if the number of overlapping sheets is two or more. However, when the number of
overlapping sheets is 10 or more, the sound pressure and the sensitivity both decrease by 3 dB
or more, which is not preferable. FIG. 2 shows another embodiment of the present invention in
which the wire mesh 12, 13 in FIG. 1 is sandwiched and held between the stopper 10 and the
case 11 to a structure in which the wire mesh 12, 13 is crimped and held by only the case 15. Is
a longitudinal sectional view of a schematic structure showing In Figs. 1 and 2, since the opening
of the case top surface opening for transmitting and receiving ultrasonic waves has a double
metal mesh structure of stainless steel SUS316 with 100 mesh or more, these ultrasonic
transducers should be used. When used in a flammable gas such as methane gas or propane gas,
ignition may occur between the electrodes on the top face of the piezoelectric body 2 facing each
other, and even if a flame is generated inside the case, it occurs within this case The flame of the
combustion is cooled by the mesh gap of the stainless steel SUS316 double wire mesh of 100
mesh or more, and the flame which causes an explosion is not transmitted to the combustible gas
outside the case.
At the same time, this double wire mesh prevents the supply of sufficient flammable gas
necessary for combustion to the case internal flame. As described above, even if a flame occurs
inside the case, it is possible to prevent the inflammable gas outside the case from being ignited
and to prevent explosion.
[0006]
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As described above, according to the ultrasonic transducer according to the present invention,
since the explosion-proof performance is provided structurally, for example, the medium is a
combustible gas such as methane gas, propane gas, etc. It can be used even in a toxic gas.
[0007]
Brief description of the drawings
[0008]
1 is a longitudinal sectional view of a schematic structure of an ultrasonic transducer showing an
embodiment of the present invention.
[0009]
2 is a longitudinal sectional view of a schematic structure of an ultrasonic transducer showing
another embodiment of the present invention.
[0010]
3 is a longitudinal sectional view of a schematic structure of a conventional ultrasonic
transducer.
[0011]
4 is a longitudinal sectional view of the schematic structure of another conventional ultrasonic
transducer.
[0012]
Explanation of sign
[0013]
Reference Signs List 1 metal plate 2 piezoelectric body 3 bimorph vibrator 4 terminal plate 5
electrode terminal 6 electrode terminal 7 additional resonator 8 lead wire 9 lead wire 10 stopper
12 case 12 wire mesh 13 wire mesh 14 elastic adhesive 15 case 16 wire mesh 17 case
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