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JP2007208381

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DESCRIPTION JP2007208381
An object of the present invention is to improve reliability by preventing a short circuit between
a hollow cylindrical case and a measurement channel. The upper electrode 3 side of a
piezoelectric body 2 is fixed to the inner surface of a top wall of a covered case 1 which is
attached to a measurement flow path 11 and conductive and the lower opening of the case 1 is
conductive. The terminal plate 5 is fixed to form an ultrasonic transducer, and the electrical
insulating member 13 is interposed between the case 1 and the measurement flow channel 11.
Therefore, the case 1 and the measurement flow passage 11 are not short-circuited by the
foreign matter such as the conductive processing burr generated during the measurement flow
passage processing, and the highly reliable ultrasonic transducer can be obtained. [Selected
figure] Figure 1
Ultrasonic transducer and fluid flow measurement device using the same
[0001]
The present invention relates to an ultrasonic transducer, and a fluid flow measurement device
configured to measure the flow velocity and flow rate of a fluid using the same.
[0002]
In the conventional ultrasonic transducer, as shown in FIG. 6, the upper electrode 53 of the
piezoelectric body 52 is adhered to the inner surface of the top wall of the cap-like conductive
case 51, and conductive is conducted to the flange 54 formed at the lower opening edge thereof.
The case 51 is sealed by welding the flexible terminal plate 55 by means of electric welding or
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the like.
In the case 51, an inert gas such as nitrogen gas is appropriately sealed.
[0003]
A contact 57 such as conductive rubber is conducted to the lower electrode 56 of the
piezoelectric body 52 facing in the case 51, and a terminal 58 penetrating the terminal plate 55
is connected to the contact 57. Of course, the contactor 57 and the terminal 58 are insulated
from the terminal plate 55 through the electrical insulating material. The other terminal 59 is
directly attached to the terminal plate 55.
[0004]
That is, the upper electrode 53 of the piezoelectric body 52 is connected to one terminal 59 via
the case 51, and the lower electrode 56 is connected to the other terminal 58 via the contactor
57.
[0005]
Then, the measurement flow channel 61 is equipped with the vibration isolation member 60
provided on the outer periphery of the case 51 (see, for example, Patent Document 1).
Japanese Patent Application Publication No. 2003-270013
[0006]
However, in the conventional ultrasonic transducer, since the top outer peripheral portion and
the upper end portion of the side wall of the case 51 are exposed to the measurement flow
channel 61, foreign matter such as conductive processing burrs generated during the
measurement flow channel processing When the voltage surge is applied from the outside, if the
voltage surge is applied from the outside, the measurement circuit may be broken if a voltage
surge is applied between the case 51 and the measurement flow channel 61, which causes a
problem of erroneous measurement operation.
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2
[0007]
The present invention solves the above-mentioned conventional problems, and an object of the
present invention is to always maintain good performance as an ultrasonic transducer without
shorting even by conductive foreign matter or the like.
[0008]
In order to achieve the above object, the present invention fixes the upper electrode side of the
piezoelectric body to the inner surface of the top wall of the ceiling case which is attached to the
measurement channel and is conductive and has conductivity in the lower opening of the case. A
terminal plate of a conductive material, in which an electrical insulating member is interposed
between the case and the measurement channel, and the case is made of foreign matter such as
conductive processing burrs generated at the time of processing the measurement channel. And
the measurement channel will not be shorted.
[0009]
According to the present invention, since the case and the measurement flow path are not shortcircuited by foreign matter such as conductive processing burrs generated at the time of
measurement flow path processing, short-circuiting occurs even when voltage surge is applied
from the outside. It is possible to provide an ultrasonic transducer which is free from occurrence
and excellent in reliability.
[0010]
According to the first aspect of the present invention, the upper electrode side of the
piezoelectric body is fixed to the inner surface of the top wall of the case having a conductivity
and attached to the measurement channel, and a terminal plate having conductivity at the lower
opening of the case An electrical insulation member is interposed between the case and the
measurement channel.
[0011]
According to a second aspect of the present invention, the upper electrode side of the
piezoelectric body is fixed to the inner surface of the top of the conductive case with a
measurement flow path, and the acoustic matching layer is fixed to the outer surface of the
upper surface. A conductive terminal plate is attached to the lower opening of the case, and an
electrical insulating member is interposed between the case and the measurement flow path
except for the portion where the acoustic matching layer is fixed.
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[0012]
In the third invention, the upper electrode side of the piezoelectric body is attached to the inner
surface of the top wall of the conductive ceiling case attached to the measurement flow path
through the electrically insulating vibration isolation member, and the outer surface of the top
case is acoustic. The matching layer is fixed respectively, and a conductive terminal plate is
attached to the lower opening of the case, and the acoustic matching layer is fixed to the outer
surface of the top wall through the electrically insulating bonding member. The outer surface of
the case was covered by the vibration proofing member and the joining member.
[0013]
The fourth invention is attached to the measurement flow path through the electrically insulating
vibration isolation member, and the upper electrode side of the piezoelectric body is on the inner
surface of the top of the conductive case and the acoustic is on the outer surface of the upper
surface. The matching layer is fixed respectively, and a conductive terminal plate is attached to
the lower opening of the case, and the outer surface of the case is covered with the acoustic
matching layer and the anti-vibration member.
[0014]
Then, according to the first to fourth inventions, even when a conductive processing burr or a
conductive foreign substance is generated at the time of processing the measurement flow path
when a voltage surge is applied from the outside, An electrical short circuit between the case and
the measurement flow path does not cause malfunction due to destruction of the measurement
circuit, and an ultrasonic transducer excellent in reliability can be provided.
[0015]
As in the fifth and sixth inventions, it is desirable that the electrically insulating member and the
vibration isolation member be formed of a material having a large acoustic attenuation
characteristic.
[0016]
According to a seventh invention, the ultrasonic transducers according to the first to sixth
inventions are installed on the upstream side and the downstream side of the fluid passage, and
the fluid passage is set based on the ultrasonic wave propagation time between the ultrasonic
transducers. The flow condition of the flowing fluid was measured.
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[0017]
Therefore, it is possible to realize reliable, high-performance flow measurement such as flow
velocity and flow rate.
[0018]
Hereinafter, embodiments of the present invention will be described with reference to the
drawings.
The present invention is not limited by the present embodiment.
[0019]
(Embodiment 1) In FIG. 1, the upper electrode 3 of the piezoelectric body 2 is adhered to the
inner surface of the top wall of the cap-like conductive case 1, and the conductive terminal plate
5 is attached to the flange 4 formed at the lower opening edge thereof. The case 1 is sealed by
welding it by means of electric welding or the like.
[0020]
An inert gas such as nitrogen gas is appropriately sealed inside the case 1.
[0021]
A contact 7 such as conductive rubber is conducted to the lower electrode 6 of the piezoelectric
body 2 facing the inside of the case 1, and a terminal 8 penetrating the terminal plate 5 is
connected to the contact 7.
Of course, the contacts 7 and the terminals 8 are insulated from the terminal plate 5 through the
electrical insulating material.
The other terminal 9 is directly attached to the terminal board 5.
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[0022]
That is, the upper electrode 3 of the piezoelectric body 2 is connected to one terminal 9 via the
case 1, and the lower electrode 6 is connected to the other terminal 8 via the contact 7.
[0023]
The ultrasonic transducer of the above-described configuration is provided in a vibration-proof
manner in the measurement flow path 11 via the vibration-proof member 10 provided on the
outer periphery of the case 1 and fixed by the fixing tool 12.
The anti-vibration member 10 covers the outer periphery of the case 1 and also the outer
periphery of the flange 4 and the terminal plate 5 welded thereto.
[0024]
Then, a cap-like electric insulating member 13 is provided on the outer peripheral surface and
the outer top surface of the case 1.
Practically speaking, the anti-vibration member 10 is mounted on the outer periphery of the
electrical insulating member 13.
[0025]
In the above configuration, when the ultrasonic transducer is attached to the measurement flow
passage 11, even if conductive foreign matter or the like generated from a processing burr or a
screwed portion is present between the case 1 and the measurement flow passage 11 Since the
electrical insulation member 13 is present, an electrical short circuit accident does not occur,
thereby preventing the measurement circuit from being broken and malfunctioning, and
providing an ultrasonic transducer excellent in reliability. it can.
[0026]
In addition, as a material for forming the electric insulating member 13 of this kind, for example,
epoxy resin, polyimide, phenol resin, melamine resin, urethane resin having large acoustic
damping characteristics, elastomer, insulating foam organic material, silicon rubber, fluoro
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rubber, Rubber materials such as nitrile rubber are suitable.
[0027]
Further, the electrical insulating member 13 can be provided with a function of damping
unnecessary vibration together with the vibration isolation member by being formed of a
material having particularly large acoustic damping characteristics.
That is, an ultrasonic transducer with less reverberation noise can be realized.
[0028]
Second Embodiment FIG. 2 shows a second embodiment, in which the acoustic matching layer 15
is disposed on the outer top surface of the case 1 via a bonding means 14 such as an adhesive. A
portion 13 covers the portion of the case 1 where the acoustic matching layer 15 is not present.
[0029]
In addition, in FIG. 2, the same code | symbol is attached | subjected about the structure which
performs the same effect | action as FIG. 1, and the thing of Embodiment 1 is used for a specific
description.
[0030]
As described above, since the outer surface of the case 1 is covered with the acoustic matching
layer 15 and the electrical insulating member 13, an electrical short is generated between the
case 1 and the measurement flow channel 11 as in the first embodiment. There is nothing to do.
[0031]
Third Embodiment FIG. 3 shows a third embodiment, wherein the bonding means 14 is extended
to the upper end of the outer peripheral surface of the case 1 to prevent electrical insulation
directly disposed on the outer peripheral surface of the case 1. The case 1 is enclosed together
with the vibration member 10.
[0032]
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The bonding means 14 uses an adhesive which is an electrically insulating thermosetting resin
such as epoxy resin.
The electrically insulating adhesive spreads and penetrates the outer top surface and the outer
peripheral wall of the case 1 by heating normally.
In addition, in FIG. 3, the same code | symbol is attached | subjected about the structure which
performs the same effect | action as FIG.1, 2, and the thing of Embodiment 1, 2 is used for a
specific description.
[0033]
As described above, the configuration in which the outer surface of the case 1 is covered with the
acoustic matching layer 15 and the electrically insulating bonding means 14 and the vibrationproof member 10, the case 1 and the measurement flow path are the same as in the first and
second embodiments. There is no occurrence of an electrical short between them and 11.
[0034]
Fourth Embodiment FIG. 4 shows a fourth embodiment, in which the electrically insulating
vibration damping member 10 disposed on the outer peripheral surface of the case 1 is extended
to the outer peripheral surface of the outer top surface to form the acoustic matching layer 15. It
is joined to the outer circumference of
[0035]
Therefore, because of the configuration in which the outer surface of case 1 is covered with
acoustic matching layer 15 and vibration isolation member 10, an electrical short circuit is made
between case 1 and measurement flow path 11 as in the first, second and third embodiments. It
does not occur.
[0036]
In addition, in FIG. 4, the same reference numerals are given to the configurations performing the
same operations as those in FIGS.
[0037]
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The material for forming the vibration-proof member 10 is not limited as long as it is an
electrically insulating material having a large acoustic damping property, and, for example, a
urethane resin, an elastomer, an insulating foam organic material, silicon rubber, fluorine Rubber
materials such as rubber and nitrile rubber are suitable.
[0038]
Fifth Embodiment FIG. 5 shows a fluid flow measurement device equipped with the ultrasonic
transducer described in any one of the first to fourth embodiments.
[0039]
A pair of ultrasonic transducers 16 and 17 are disposed opposite to each other on the upstream
side and the downstream side of the measurement flow channel 11 in which a fluid such as gas
or liquid flows so that ultrasonic waves propagate obliquely.
Then, the transmission path of the ultrasonic wave L1 propagates from the ultrasonic transducer
16 on the upstream side to the ultrasonic transducer 17 on the downstream side, and L2 is the
ultrasonic wave on the upstream side from the ultrasonic transducer 17 disposed on the
downstream side The transmission paths of the ultrasonic waves propagating to the vibrator 16
are shown.
[0040]
Let V be the flow velocity of the fluid flowing through the measurement flow channel 11, C be
the velocity of the ultrasonic wave in the fluid, and θ be the angle between the fluid flow
direction and the ultrasonic wave propagation direction.
When the ultrasonic transducer 16 is on the ultrasonic wave transmitting side and the ultrasonic
transducer 17 is on the ultrasonic wave receiving side, propagation time t1 for the ultrasonic
wave emitted from the ultrasonic transducer 16 to reach the ultrasonic transducer 17 Is
expressed by t1 = L / (C + V cos θ) (1)
[0041]
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Next, contrary to the above, the propagation time t2 for the ultrasonic wave emitted from the
ultrasonic transducer 17 to reach the ultrasonic transducer 16 is expressed by the following
equation: t2 = L / (C−V cos θ) (2)
[0042]
Then, if the sound velocity C of the fluid is eliminated from the equations (1) and (2), the
equation V = L / 2 cos θ (1 / t1-1 / t2) (3) is obtained.
[0043]
If L and θ are known, the flow velocity V can be obtained by measuring t1 and t2 in the
measuring circuit 18.
If necessary, the flow rate Q can be obtained by multiplying the flow velocity V by the crosssectional area S of the measurement flow passage 11 and the correction coefficient K.
The calculating means 19 calculates the above Q = KSV.
[0044]
As described above, by using the ultrasonic transducers 16 and 17 according to the embodiment,
there is no reduction in reliability even if machining burrs and conductive foreign matter are
present in the measurement flow channel 11, and flow measurement with high accuracy Can be
realized.
[0045]
As mentioned above, since the ultrasonic transducer concerning the present invention is
excellent in reliability, a high-performance ultrasonic flow velocity and a flow meter can be
realized, and a household gas meter, which requires long-term reliability, water supply It is
applicable to uses such as a meter.
[0046]
Cross-sectional view of the ultrasonic transducer in the first embodiment of the present invention
Cross-sectional view of the ultrasonic transducer in the second embodiment of the present
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invention cross-sectional view of the ultrasonic transducer in the third embodiment of the
present invention Cross-sectional view of ultrasonic transducer in mode 4 Cross-sectional view of
fluid flow measurement device in the fifth embodiment of the present invention Cross-sectional
view of a conventional ultrasonic transducer
Explanation of sign
[0047]
Reference Signs List 1 case 2 piezoelectric body 3 upper electrode 5 terminal plate 10 vibration
damping member 11 measurement flow path 13 electric insulating member 14 bonding member
15 acoustic matching layer 16, 17 ultrasonic transducer
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