close

Вход

Забыли?

вход по аккаунту

?

DESCRIPTION JP2003270011

код для вставкиСкачать
Patent Translate
Powered by EPO and Google
Notice
This translation is machine-generated. It cannot be guaranteed that it is intelligible, accurate,
complete, reliable or fit for specific purposes. Critical decisions, such as commercially relevant or
financial decisions, should not be based on machine-translation output.
DESCRIPTION JP2003270011
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an
ultrasonic transducer for transmitting and receiving ultrasonic pulses and an ultrasonic
flowmeter for measuring the flow rate of gas or liquid using the ultrasonic transducer. .
[0002]
2. Description of the Related Art In the conventional ultrasonic transducer of this type, a lead
wire is connected to an electrode surface to electrically connect the electrode surface of the
piezoelectric body to the external electrode. I was soldering. However, in the electrical connection
method using soldering, variations in the frequency characteristics and transmission / reception
sensitivity of the ultrasonic transducer occur due to the thermal effect on the soldered place and
the amount of solder adhering, and this ultrasonic transducer In the case of using an ultrasonic
flowmeter, there is a problem that it affects the measurement accuracy.
[0003]
Therefore, as a method of not using soldering for the electrical connection, there is one disclosed
in Japanese Patent Application Laid-Open No. 2001-50785. As shown in FIG. 4, this ultrasonic
transducer is electrically connected by pressing the elastic body 20 having conductivity between
the electrode surface 7a of the piezoelectric body 7 and the terminal 8a of the terminal plate 8 to
13-04-2019
1
pressurize it. I am trying to Specifically, as shown in the figure, the conductive body 20 made of
silicon-based rubber and the elastic body 20 configured to hold elasticity by alternately
arranging the conductive layers 20 a and the insulating layers 20 b are shown in FIG. After being
dropped into the recess 19, the piezoelectric body 7 and the terminal 8a are sandwiched and
pressurized, and in this state, the outer peripheral portion 8c of the terminal plate 8 and the
flange portion 11a of the case 11 containing the piezoelectric body 7 are electrically welded. It is
joined. The terminals 8a and 8b provided on the terminal plate 8 are electrically insulated by a
glass (insulation portion) 14. As a result, the electrode surface 7a and the terminal 8a are
electrically connected, and the other electrode surface 7b is electrically connected to the terminal
8b via the case 11 also serving as the external electrode and the outer peripheral portion 8c of
the terminal plate 8 The sealed space 13 formed by the case 11 and the terminal plate 8 is filled
with nitrogen gas.
[0004]
However, in the conventional electrical connection method of the ultrasonic transducer, since the
elastic body 20 is only sandwiched between the piezoelectric body 7 and the terminal plate 8, the
recess of the terminal plate 8 is formed. Easy to move laterally in 19 Therefore, when moving,
the lower surface of the conductive layer 20a arranged in a layer comes into contact with the
glass 14 which is the insulating portion, causing a problem that conduction failure occurs and
efficient conduction can not be achieved.
[0005]
Therefore, in order to restrict lateral movement of the elastic body 20, it is conceivable to
provide a holding hole in the terminal plate 8 and hold the elastic body 20 by the holding hole. In
such a case, the conventional method shown in FIG. Since the space around the elastic body 20
as in the example is not formed, and is closely attached to the inner peripheral surface of the
holding hole, when there is a gap below it, the air in the gap is filled with nitrogen gas. There is a
risk that the air will not be evacuated well and will remain as an air reservoir that is not replaced
by nitrogen gas. In particular, in the case where the insulating portion is formed of a glass
material inside the holding hole, it is necessary to prevent the surface expansion and make the
head of the terminal 8a project from the surface of the insulating portion. (In practice, the head
of the terminal 8a can not be flush with the surface of the glass 14 as in the prior art).
[0006]
13-04-2019
2
The air remaining in the air pool oxidizes the electrode surface 7a of the piezoelectric body 7 to
cause conduction failure, and the epoxy resin bonding the piezoelectric body 7 to the case 11
reacts with moisture to cause the epoxy resin It swells, the reliability of adhesion may be
reduced, and conduction failure may occur.
[0007]
Further, the height of the elastic body 20 is set smaller than the maximum dimension of the cross
section so that the conductive layer 20a arranged in a layer is not buckled by pressure during
assembly, and the direction of insertion into the recess 19 There is also a problem that an
insertion error (the conductive layer 20a is in the lateral direction) is likely to occur at the time of
assembly because the insertion is possible even if the error is wrong.
[0008]
Therefore, the present invention solves the above-mentioned conventional problems, easily holds
an elastic body in a proper direction and prevents conduction failure, and has high reliability
ultrasonic transducer, and a pair of ultrasonic transducers. An object of the present invention is
to provide an ultrasonic flowmeter that can be used for accurate measurement.
[0009]
SUMMARY OF THE INVENTION In order to achieve the above object, the present invention is
directed to a terminal plate having two external electrode terminals respectively electrically
connected to a pair of electrode surfaces of a piezoelectric body, one of the piezoelectric body A
holding hole for holding the conductive elastic body held between the electrode surface of the
electrode and one of the external electrode terminals, and the elastic body is formed into an
outer peripheral surface with respect to the inner peripheral surface of the holding hole. It forms
so that it may contact partially and a space part is formed between the said inner skin and the
said side skin.
[0010]
According to the invention, the elastic body having conductivity can be brought into partial
contact with the holding hole to restrict the lateral movement, and the conduction failure due to
the movement of the elastic body can be prevented. As well as the improvement, the assembly
operation can be facilitated because the subsequent assembly can be performed with the elastic
body held by the terminal plate.
13-04-2019
3
Further, since the exhaust is performed by the space portion formed between the side peripheral
surface of the elastic body and the inner peripheral surface of the holding hole, the space formed
below the elastic body in the holding hole does not become an air accumulation. It is possible to
prevent the occurrence of conduction failure due to oxidation of the electrode surface of the
piezoelectric body, and in the case where the piezoelectric body is adhered to the case with an
epoxy resin, the reliability of adhesion decreases due to swelling of the epoxy resin It is possible
to prevent conduction failure caused by
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION An ultrasonic transducer according to a first
aspect of the present invention comprises a piezoelectric body having a pair of opposing
electrode surfaces, and two external electrodes electrically connected to the respective electrode
surfaces. In an ultrasonic transducer including a terminal plate having a terminal and an elastic
body having conductivity interposed between one electrode surface of a piezoelectric body and
one external electrode terminal, the terminal plate is made of the elastic material. The elastic
body is formed so that the side peripheral surface has an irregular shape and is partially in
contact with the inner peripheral surface of the holding hole, and the elastic body is formed with
the inner peripheral surface and the side. A space part is formed between the peripheral surface.
[0012]
According to this ultrasonic transducer, the conductive elastic body is held by the holding hole of
the terminal plate with the side peripheral surface being in partial contact with each other, and
the electrode surface of the piezoelectric body and the external electrode terminal Since the
sandwiching is performed, the lateral movement can be restricted, and the conduction failure due
to the movement of the elastic body can be prevented, thereby improving the reliability.
Further, as compared with the conventional method in which only the elastic body is held
between the piezoelectric body and the terminal plate, the subsequent assembly can be
performed in the state of being held by the terminal plate, which facilitates the assembly
operation.
Furthermore, even if a gap is created below the elastic body after the holding, the side peripheral
surface of the elastic body and the inner peripheral surface of the holding hole are different in
shape and a space is formed. The space is communicated with the sealed space formed by the
13-04-2019
4
case containing the body and the terminal plate, and the space can be reliably exhausted so that
the space does not become an air accumulation.
Therefore, it is possible to prevent the electrode surface of the piezoelectric body from being
oxidized by the air remaining in the air reservoir to cause the conduction failure.
Further, in the case where the piezoelectric body is adhered to the case with an epoxy resin, the
reliability of the adhesion due to the swelling of the epoxy resin can be reduced, and the
conduction failure caused thereby can be prevented. Of course, since solder is not used for the
electrical connection between the electrode surface of the piezoelectric body and the external
electrode terminal, it is not affected by the frequency characteristic or the transmission /
reception sensitivity.
[0013]
An ultrasonic transducer according to a second aspect of the present invention is the ultrasonic
transducer according to the first aspect, wherein the elastic body is disposed around a conductive
portion disposed at a central position in the axial direction, and the periphery thereof. It is
preferable that the insulating portion of the outer peripheral portion can be insulated from the
conductive terminal plate when the elastic body is held in the holding hole. . In addition, by
forming the conductive portion in a shaft shape, efficient conduction can be achieved, and cost
reduction of battery power can be achieved.
[0014]
An ultrasonic transducer according to a third aspect of the present invention is the ultrasonic
transducer according to the first or second aspect, wherein the elastic body is formed into a
polygonal cross-sectional shape, and a space is provided along the entire outer periphery. Since
the part can be formed, the space part can be reliably secured even in the event of lateral
deviation, and in the case of a regular polygon, the inner peripheral surface of the holding hole as
described later The concentric position with respect to can be reliably maintained.
[0015]
An ultrasonic transducer according to a fourth aspect of the present invention is the ultrasonic
transducer according to any one of the first to third aspects, wherein the holding hole of the
terminal plate has a circular cross-sectional shape. , Processing of the terminal plate becomes
13-04-2019
5
easy.
[0016]
An ultrasonic transducer according to a fifth aspect of the present invention is the ultrasonic
transducer according to any one of the first to fourth aspects, wherein the elastic body is kept
concentric with the inner circumferential surface of the holding hole. As described above, a
plurality of contact portions are formed on the side peripheral surface, so that uniform pressing
can be performed on the elastic body, and it is particularly effective particularly in the second
embodiment, and the shaft-like conductive portion is held. It is possible to ensure stable and
efficient conduction at the center position of the hole, which is preferable.
[0017]
An ultrasonic transducer according to a sixth aspect of the present invention is the ultrasonic
transducer according to any one of the first to fifth aspects, wherein the elastic body has a height
greater than the maximum dimension of the cross section of the holding hole. When inserting the
elastic body into the holding hole, it is possible to easily grasp the vertically elongated one, and it
is possible to insert only in the insertion direction in the held state, so there is no mistake in the
insertion direction. Insertion errors can be prevented.
[0018]
An ultrasonic transducer according to a seventh aspect of the present invention is the ultrasonic
transducer according to any one of the first to sixth aspects, wherein the ratio of the height of the
elastic body to the maximum dimension of its cross section is The conductive part is set to be
within the buckling limit at which conduction failure occurs, and the conduction material can be
prevented from causing conduction failure due to strong pressure, which is particularly effective
in the second embodiment. It is.
[0019]
The ultrasonic flowmeter according to the present invention comprises a flow rate measuring
unit for measuring the flow rate of fluid flowing through a flow passage, and a pair of ultrasonic
wave transmitters / receivers of any one of the first to seventh embodiments provided in the flow
rate measuring unit. And a flow rate calculation circuit for obtaining a flow rate based on a signal
from the measurement circuit, as described above. The measurement accuracy can be improved
by using an ultrasonic transducer which can achieve efficient electrical connection without
causing a problem and can easily match the characteristics without using solder.
13-04-2019
6
[0020]
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present
invention will be described below with reference to FIGS.
[0021]
FIG. 1 is a schematic block diagram of an ultrasonic flowmeter using an ultrasonic transducer
according to the present invention.
In FIG. 1, 1 is a flow path through which a fluid such as LP gas or natural gas flows, 2 is a flow
rate measuring unit for measuring the flow rate of the fluid flowing through the flow path 1, and
3 and 4 face the flow path 1 , A measuring circuit for measuring the ultrasonic wave propagation
time between the ultrasonic transducers 3 and 4, and 6 a flow rate based on the signal from the
measuring circuit 5. It is a flow rate operation circuit to be determined.
[0022]
The operation of the ultrasonic flowmeter in the flow rate measuring unit 2 configured as
described above will be described.
A distance connecting the centers of the ultrasonic transducer 3 and the ultrasonic transducer 4
is L, and an angle between the straight line and the longitudinal direction of the flow path 1
which is the flow direction is θ.
Further, the velocity of sound in a windless state of the fluid is denoted by C, and the flow
velocity of the fluid in the flow passage 1 is denoted by V.
The ultrasonic waves transmitted from the ultrasonic transducer 3 disposed on the upstream side
of the flow rate measuring unit 2 diagonally cross the flow path 1 and are received by the
ultrasonic transducer 4 disposed on the downstream side.
The propagation time t1 at this time is
13-04-2019
7
[0023]
It is indicated by.
Next, ultrasonic waves are transmitted from the ultrasonic transducer 4 and received by the
ultrasonic transducer 3.
The propagation time t2 at this time is
[0024]
It is indicated by. And when the sound velocity C of the fluid is eliminated from the equations of
t1 and t2,
[0025]
The equation of is obtained. If L and θ are known, the flow velocity V can be obtained by
measuring t1 and t2 in the measuring circuit 5. From the flow velocity V, assuming that the
cross-sectional area of the flow path 1 is S and the correction coefficient is K, the flow rate
calculation circuit 6 can calculate Q = KSV to obtain the flow rate.
[0026]
The ultrasonic transducer used for the ultrasonic flowmeter which performs flow measurement
by the above principle of operation is demonstrated using FIG. 2 and FIG. Fig. 2 is a longitudinal
sectional view showing the ultrasonic transducer, and Fig. 3 shows the main part (central part of
the terminal plate) in the ultrasonic transducer, and (a) is a plan view when viewed from above.
(B) is the longitudinal cross-sectional view.
13-04-2019
8
[0027]
In FIG. 2, the ultrasonic transducer 3 (4) comprises a piezoelectric body 7 having a pair of
opposing electrode surfaces 7a and 7b, and an external electrode terminal 8a electrically
connected to each of the electrode surfaces 7a and 7b. Between the terminal plate 8 having the
8b and the electrode surface 7a of the piezoelectric body 7 and the external electrode terminal
8a, the terminal plate 8 is held by the holding hole 9 formed at the center of the terminal plate 8
to have electrical conductivity And an elastic body 10. The piezoelectric body 7 is adhered to the
inner surface of the top portion of the stainless steel case 11 having a flange portion 11a with an
epoxy-based adhesive, and the acoustic matching layer 12 is formed on the opposite side, that is,
the outer surface of the top portion of the case 11. It is bonded by an epoxy adhesive. The
grooves 7c provided in the piezoelectric body 7 are for making thickness longitudinal vibration
the main mode in order to transmit and receive ultrasonic waves efficiently. Further, by reducing
the thickness of the adhesive to the case 11, the piezoelectric body 7 can achieve the electrical
connection between the electrode surface 7 b and the case 11 simultaneously with the bonding
and fixing.
[0028]
The conductive elastic body 10 may be made of a conductive elastic material such as silicone
rubber, or any other elastic material as long as it is an elastic body having conductivity. A column
is used which is formed of a conductive portion 10a disposed at a position and an insulating
portion 10b disposed around the conductive portion 10a. The elastic body 10 is held in the
holding hole 9 of the terminal plate 8, and is held between the piezoelectric body 7 and the
external electrode terminal 8a to be pressurized. In this state, the outer peripheral portion 8c of
the terminal plate 8 and the case 11 are The flange portion 11a is joined by electric welding.
Then, a sealed space 13 is formed by the case 11 and the terminal plate 8, and the sealed space
13 is exhausted and replaced with an inert gas such as nitrogen gas.
[0029]
The terminal plate 8 is made of metal, and the terminal 8b is provided in the vicinity of the outer
peripheral portion 8c, and the terminal 8a is provided in the center, but glass (insulation portion)
is provided around the terminal 8a (inside of the holding hole 9). By providing 14), the terminals
8a and 8b are electrically isolated from each other. As a result, the electrode surface 7a and the
terminal 8a are electrically connected, and the electrode surface 7b is electrically connected to
13-04-2019
9
the terminal 8b via the case 11 also serving as the external electrode and the outer peripheral
portion 8c of the terminal plate 8. When the entire elastic body 10 is molded of conductive
rubber, since it conducts with the terminal plate 8 when held in the holding hole 9, the position
where the glass 14 is provided is on the outer peripheral side from the circumference of the
holding hole 9 It is necessary to provide and to insulate between the two terminals 8a and 8b.
[0030]
The holding hole 9 is shown in a plan view of FIG. 3A (where the interface with the piezoelectric
body 7 is viewed from above). As shown in), the cross-sectional shape is formed in a circular
shape, and the elastic body 10 is formed in a regular hexagonal shape in a cross-sectional shape.
That is, the elastic body 10 is formed such that the side peripheral surface 10 c is formed
differently to the inner peripheral surface 9 a of the holding hole 9 and partially in contact. As a
result, a space 15 communicating with the sealed space 13 is formed between the side peripheral
surface 10 c of the elastic body 10 and the inner peripheral surface 9 a of the holding hole 9. If
the inner peripheral surface 9a and the side peripheral surface 10c are formed in substantially
the same shape with emphasis on the holding of the elastic body 10 in the holding hole 9, the
elastic body 10 is formed inside the holding hole 9 below. When the gap S is replaced with the
nitrogen gas, it becomes an air reservoir, and the electrode surface 7a of the piezoelectric body 7
is oxidized due to the influence of the air, causing a conduction failure, or the case 11 and the
piezoelectric body 7 The bonding epoxy adhesive swells to lower the reliability of bonding, or if
the thickness of the bonding increases, problems such as affecting the electrical connection
through the case 11 may occur.
[0031]
Further, partial contact of the elastic body 10 is realized by forming a plurality of contact
portions 10 d on the side circumferential surface 10 c so as to maintain a concentric position
with respect to the holding hole 9. That is, when the elastic body 10 is a regular polygon as in the
present embodiment, the six sides in the longitudinal direction become the contact portion 10d
partially contacting the inner peripheral surface 9a of the holding hole 9, and the radius of the
cross section The radius of the cross section of the holding hole 9 is also r, which is preferable
because it can be reliably positioned at the center of the holding hole 9 of the conductive portion
10a. In addition, as long as the side circumferential surface 10c and the inner circumferential
surface 9a are in an irregular relationship with each other as described above, and such a
positional relationship can form the space portion 15 by partial contact, the present embodiment
In addition to the shape shown in the example, it is also possible to apply various other shapes,
13-04-2019
10
such as when the cross-sectional shape of the holding hole 9 is square and the cross-sectional
shape of the elastic body 10 is circular.
[0032]
Further, since the height H of the elastic body 10 is larger than the maximum dimension R of the
cross section of the holding hole 9 as shown in an enlarged manner in FIG. When inserting, it is
possible to easily grip the vertically elongated one, and since it is possible to insert only in the
inserted direction in the gripped state, the insertion direction can not be mistaken and an
insertion error can be prevented. The height H of the elastic body 10 is set so that the ratio to the
maximum dimension R of the cross section (= the maximum dimension R of the holding hole 9) is
within the buckling limit at which the conductive portion 10a becomes conductive failure. ing.
This is because, for example, if conductive metal particles in which nickel particles are plated
with gold to have conductivity are used as the conductive material, conduction failure will occur
if pressure is applied beyond the limit, and such By setting the height ratio, the conductive
material of the conductive portion 10a can be pressurized without causing buckling.
[0033]
Furthermore, the elastic body 10 has a stepped shape on both upper and lower surfaces. That is,
the pressing can be efficiently performed on the upper surface, and the elastic material of the
insulating portion 10b presses the head of the terminal 8a by pressing on the lower surface, and
the electrical contact between the terminal 8a and the conductive portion 10a of the elastic body
10 is weakened. You can prevent that. In addition, since the stepped shape is symmetrical in the
vertical direction, the vertical direction is not restricted when inserted into the holding hole 9,
which facilitates the assembly and the processing thereof, which is preferable. Further, in the
present embodiment, the conductive portion 10a is formed in a shaft shape, and the head of the
terminal plate 8 can be brought into contact with the conductive portion 10a in order to
efficiently conduct point-wise conduction, thereby reducing the cost of conduction. it can.
[0034]
In the ultrasonic transducer 3 (4) configured as described above, a soldering method of lead
wires is not used, so a pair of ultrasonic transducers in which characteristics with no variation in
frequency characteristics and transmission / reception sensitivity match are obtained. As well as
13-04-2019
11
being able to be obtained, retention by the terminal plate 8 prevents poor conductivity due to
lateral movement of the elastic body 10 having conductivity, does not create an air pool in the
case 11, and conductivity caused by oxidative corrosion by air Defects can also be prevented. The
measurement accuracy can be improved by using such a highly reliable ultrasonic transducer for
an ultrasonic flow meter.
[0035]
The present invention can be configured in various modes other than those shown in the above
embodiment. For example, the inner shape of the piezoelectric body in the case and the shapes of
the holding hole of the terminal plate and the elastic body are limited to the illustrated shape. I
will not.
[0036]
As is apparent from the above description, according to the present invention, the following
effects can be obtained.
[0037]
According to the first ultrasonic transducer of the present invention, the terminal plate can be
held in the holding hole to restrict the lateral movement thereof, and the conduction defect due
to the movement of the elastic body can be prevented and the reliability can be improved. The
structure is high and easy to assemble, and it is possible to prevent the occurrence of air
accumulation and to prevent the conduction failure due to the oxidation of the electrode surface
of the piezoelectric body and the deterioration of the adhesion reliability of the adhesive surface
of the epoxy resin.
[0038]
According to the second ultrasonic transducer of the present invention, when the elastic body is
held in the holding hole, insulation with the terminal plate can be achieved, and the conductive
portion is formed into an axial shape for efficient conduction. Thus, the cost of battery power can
be reduced.
[0039]
According to the third ultrasonic transducer of the present invention, the space can be reliably
secured even in the event of lateral deviation.
13-04-2019
12
[0040]
According to the fourth ultrasonic transducer of the present invention, processing of the terminal
plate is facilitated.
[0041]
According to the fifth ultrasonic transducer of the present invention, the elastic body can be
uniformly pressurized, and in particular, it is particularly effective in the second ultrasonic
transducer, and the shaft-shaped conductive portion can be held by the holding hole. It is
possible to ensure stable and efficient conduction at the center position of the
[0042]
According to the sixth ultrasonic transducer of the present invention, when the elastic body is
inserted into the holding hole, the elastic body can be easily grasped and the insertion direction
can be prevented from being mistaken, so that an insertion error can be prevented.
[0043]
According to the seventh ultrasonic transducer of the present invention, the conductive material
can be prevented from causing a conduction failure due to a strong pressing force, and is
particularly effective particularly in the second ultrasonic transducer.
[0044]
According to the ultrasonic flowmeter of the present invention, as described above, efficient
electrical connection can be achieved without causing conduction failure, and the first to seventh
characteristics can be easily matched without using solder. Measurement accuracy can be
improved by measuring the flow rate using an ultrasonic transducer.
13-04-2019
13
Документ
Категория
Без категории
Просмотров
0
Размер файла
25 Кб
Теги
description, jp2003270011
1/--страниц
Пожаловаться на содержимое документа