JPH08247876A - Piezo electric film and both fluid vibration detection sensor and fluidic flow meter employing the piezo electric film - Google Patents

Abstract

PURPOSE: To increase the flexibility of each piezo electric film after a punching process has been over, facilitate operations for mounting a fluid vibration sensor onto a cylindrical support member, make identical a mounting condition such as tension and the like between the two piezo electric films, and sufficiently prevent the films from being adversely affected by pressure fluctuation and mechanical vibration which are identical in phase. CONSTITUTION: One stripe of a folded section 35c is formed in a piezo electric film main body 35a. The folded section 35c is curved so as to be formed so that it is projected upward out of the surface of the piezo electric film main body 35a. The plane shape of the folded section 35c is in a circle shape which is coaxial with the peripheral section 35b of the piezo electric film main body 35a. After the piezo electric film main body 35a has been formed by punching piezo electric material in a sheet shape into a profile specified in size (circle shape), the piezo electric main body 35a is so manufactures as to be pressed and molded into the folded section 35c. The flexibility of the piezo electric film main body 35a is increased by the folded section 35c, and it can thereby be reasonably mounted onto a cylindrical support member.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric film which vibrates due to a differential pressure based on fluid vibration and outputs an electric signal in accordance with the differential pressure, a fluid vibration detection sensor using the same, and a fluidic flowmeter. .

[0002]

2. Description of the Related Art Conventionally, as this type of piezoelectric film, one applied to a fluidic flowmeter has been known. In this fluidic flow meter, a piezoelectric film is stretched between two pressure chambers of a pressure fluctuation detection unit, and a pressure corresponding to fluid vibration of a fluid alternately flowing through a pair of feedback channels is applied to the two pressure chambers. The piezoelectric film is introduced to vibrate the piezoelectric film according to the pressure difference between the two pressure chambers, and the piezoelectricity of the piezoelectric film is used to output an electric signal corresponding to the fluid vibration.

As this fluid vibration detection sensor, for example, as disclosed in Japanese Utility Model Laid-Open No. 1-58119, a pair of pressure fluctuation detection is performed for the purpose of removing noise such as in-phase pressure fluctuation and external mechanical vibration. Some have parts. With this fluid vibration sensor, the pressure due to fluid vibration is 2
The two piezoelectric films are applied in opposite directions, whereas in the case of in-phase pressure fluctuation and pressure due to external mechanical vibration, they are in the same direction. The effect is eliminated by offsetting the output of the membrane. Therefore, in this type of fluid vibration sensor, in order to ensure the detection accuracy, the uniformity of the piezoelectric film and the attachment state with respect to the pressure chamber must be uniform in each of the two pressure fluctuation detection units.

By the way, in the conventional fluid vibration detection sensor, the piezoelectric film is manufactured by punching a flat and large sheet into a circular shape, and after punching, as shown in FIG. , Piezoelectric film 13
5 is in a state of being curved back in a spherical shape in the punching direction. On the other hand, as shown in FIGS. 12 and 13, the gripping surface 136 of the cylindrical support members 136A and 136B for gripping the peripheral edge portion 135b of the piezoelectric film body 135a from both sides.
a, 136b are horizontal surfaces, and these gripping surfaces 136a,
The piezoelectric film 135 is fixed by 136b.

[0005]

However, in this conventional method, even if the piezoelectric films 135 used for the two pressure fluctuation detecting portions are formed uniformly with each other, the flexibility of the piezoelectric film 135 remains warped. Since it is a poor state, it is difficult to make the two pressure fluctuation detecting portions have completely the same mounting state (tension generated in the piezoelectric film 135 during mounting, difference in sphericity, etc.). Therefore, when the mechanical properties of the two piezoelectric films 135 are greatly different from each other and noise such as the above-described in-phase pressure fluctuation or mechanical vibration from the outside occurs, these influences can be sufficiently eliminated. There was a problem that I could not.

Further, there is a problem that the work of attaching the piezoelectric film 135 to the cylindrical support members 136A and 136B is complicated.

The present invention has been made in view of the above problems. A first object of the present invention is to improve flexibility after punching and to attach the fluid vibration sensor to a tubular support member without difficulty. , Easy to install,
An object of the present invention is to provide a piezoelectric film capable of making the attachment state such as tension applied to the main body substantially uniform.

A second object of the present invention is to facilitate the work of working the tubular support member, to easily attach the piezoelectric film to the tubular support member, and to further reduce in-phase pressure fluctuations. Another object of the present invention is to provide a fluid vibration detection sensor capable of sufficiently eliminating the influence of mechanical vibration applied from the outside and improving detection accuracy.

Further, a third object of the present invention is to provide a fluidic flowmeter which can detect a fluid vibration with high accuracy and calculate an accurate flow rate by using the fluid vibration detection sensor of the present invention. .

[0010]

A piezoelectric film according to the present invention is a piezoelectric film formed by punching a sheet-shaped piezoelectric material, the piezoelectric film body and the piezoelectric film body. It has at least one fold that is curved and formed so as to protrude from the surface of the piezoelectric film main body along the peripheral portion.

In this piezoelectric film, since the folds are formed on the piezoelectric film main body, the folds increase the flexibility of the entire piezoelectric film main body even if the piezoelectric film is formed in a warped state by punching. . Therefore, it can be easily attached to the tubular support, the attachment work is facilitated, and the attachment state of the piezoelectric film (that is, the tension generated in the piezoelectric film main body) can be made uniform. .

The pleats formed on the piezoelectric film main body are such that a plurality of folds of the pleats both project from the surface of the piezoelectric film main body in the same direction, and the folds of the plurality of pleats adjacent to each other are piezoelectric. A mode in which different ridges protrude from the surface of the membrane body in different directions, a mode in which adjacent folds of a plurality of folds are continuously provided, and adjacent folds of a plurality of folds are constant to each other It is possible to adopt any of the modes in which they are provided apart from each other.

The fluid vibration sensor of the present invention is a fluid vibration detection sensor for detecting fluid vibration based on a differential pressure fluctuation between a pair of pressure chambers arranged opposite to each other, and between the pair of pressure chambers. The piezoelectric film according to any one of claims 1 to 5, which is disposed and vibrates in response to fluctuations in the differential pressure between the two pressure chambers, and a contact surface between the piezoelectric film and the piezoelectric film is the piezoelectric film. A pair of cylindrical support members that are formed to be flat surfaces substantially parallel to the direction in which the film is arranged and that hold the peripheral edge of the piezoelectric film from both sides by these flat surfaces. is there.

In this fluid vibration detecting sensor, since the piezoelectric film of the present invention having an increased flexibility is used, the contact surface (holding surface) with each piezoelectric film of each of the pair of cylindrical supporting members is the arrangement of the piezoelectric film. Even if the piezoelectric film is formed to have a flat surface substantially parallel to the installation direction, the piezoelectric film can be easily attached to the cylindrical support member. That is, the contact surface of the tubular support member with the piezoelectric film does not have to be an inclined surface corresponding to the shape of the piezoelectric film after punching, and therefore the work of the tubular support member is easy. Also, the work of attaching the piezoelectric film to the tubular support member is simplified.

Further, the fluid vibration detecting sensor of the present invention comprises a first pressure fluctuation detecting section having a first pressure chamber and a second pressure chamber, and a first pressure chamber of the first pressure fluctuation detecting section. And a second pressure fluctuation detection unit having a first pressure chamber and a second pressure chamber whose positional relationship is set opposite to each other with respect to the second pressure chamber, and two flows in which fluids alternately flow The pressure based on the fluid vibration of one of the channels is set to the first value.
Of the first pressure fluctuation detecting section and the second pressure which are introduced into the first pressure chambers of the pressure fluctuation detecting section and the second pressure fluctuation detecting section and which are based on the fluid vibration of the other flow path. A fluid vibration detecting sensor adapted to be introduced into a second pressure chamber of a fluctuation detecting unit, wherein the first pressure fluctuation detecting unit and the second pressure fluctuation detecting unit respectively include a first pressure chamber and a second pressure chamber. The piezoelectric film of the present invention is disposed between the pressure chamber and the pressure chamber.

In this fluid vibration detecting sensor, in the first pressure fluctuation detecting section and the first pressure fluctuation detecting section,
Each piezoelectric film vibrates due to the differential pressure fluctuation. Here, in the first pressure fluctuation detection unit and the first pressure fluctuation detection unit,
Since the positional relationships between the first pressure chambers and the second pressure chambers are set to be opposite to each other, the piezoelectric films vibrate in mutually opposite directions and an electric signal corresponding to the fluid vibration is generated. Is output. On the other hand, when pressure fluctuations in the same phase occur or mechanical vibration or the like is applied from the outside, the two piezoelectric films both vibrate in the same direction, and therefore, it is distinguished from the case of fluid vibration.

At this time, in the fluid vibration detecting sensor of the present invention, the piezoelectric film of the present invention is used in each of the first pressure fluctuation detecting section and the second pressure fluctuation detecting section.
Attachment state of two piezoelectric films (tension applied to the piezoelectric film, etc.)
Individual differences are reduced to be substantially uniform, ie their mechanical properties are the same. For this reason, it is possible to sufficiently eliminate the effects of in-phase pressure fluctuations and external mechanical vibration.
As a result, the accuracy of fluid vibration detection is improved.

The fluidic flow meter of the present invention comprises an inlet part for receiving a fluid, a nozzle part for passing the fluid received from the inlet part to generate a jet flow, and a fluid for passing through the nozzle part 7. A fluid vibration is detected by introducing a pair of feedback flow paths leading to the outlet side and a fluid alternately flowing through the pair of feedback flow paths.
Alternatively, the fluid vibration detecting sensor described in 7 and the flow rate calculating means for calculating the flow rate of the fluid received from the inlet portion based on the fluid vibration detected by the fluid vibration detecting sensor.

In this fluidic flow meter, the fluid received from the inlet portion passes through the nozzle portion and becomes a jet flow, and the jet flow alternately flows through the pair of feedback flow paths. The fluid vibration of the fluid that alternately flows through the pair of feedback flow paths is detected by the fluid vibration detection sensor of the present invention. Further, the flow rate of the fluid received from the inlet portion is calculated based on the detected fluid vibration. Since the fluidic flow meter of the present invention uses the fluid vibration detection sensor of the present invention with improved fluid vibration detection accuracy, the flow rate detection accuracy is improved.

[0020]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a schematic structure of a fluidic flowmeter according to an embodiment of the present invention. This fluidic flowmeter detects fluid vibration of a fluid alternately flowing through a pair of feedback flow paths 21 and 22 formed inside the flowmeter main body 10 by a fluid vibration detection sensor 30, and this fluid vibration causes a fluid vibration. The flow rate calculator 60 calculates the flow rate of the fluid based on the correlation with the flow rate.

FIG. 2 shows a sectional structure of the flowmeter main body 10 according to this embodiment. The flowmeter main body 10 has an inlet 11 for receiving a fluid and an outlet 12 for discharging the fluid. A fluid flow path 13 is formed in the flowmeter body 10 between the inlet portion 11 and the outlet portion 12. In the fluid passage 13, there is provided a nozzle portion 14 for passing the fluid received from the inlet portion 11 to generate a jet flow. On the downstream side of the nozzle portion 14, a pair of side walls 16 and 17 forming an enlarged flow path are provided. A target 18 is provided on the upstream side and a target 19 is provided on the downstream side with a predetermined space between the side walls 16 and 17. A pair of feedback channels 21 and 22 are formed outside the side walls 16 and 17 to return the fluid that has passed through the nozzle portion 14 to the ejection port side of the nozzle portion 14 along the outer peripheral portions of the side walls 16 and 17. Guide 2
3 are provided. The return guide 2 is provided between each outlet portion of the feedback flow paths 21 and 22 and the outlet portion 12.
By the rear surface of 3 and the flowmeter main body 10, a pair of discharge paths 2
4, 25 are formed. Pressure guiding holes 26 and 27 are provided in the vicinity of the ejection port of the nozzle portion 14 so as to correspond to the feedback flow paths 21 and 22. These pressure guiding holes 26, 27
Is communicated with a fluid vibration detection sensor 30 (see FIG. 3) described later.

FIG. 3 shows a sectional structure of the fluid vibration detecting sensor 30 according to this embodiment. The fluid vibration detection sensor 30 includes an airtight container 31, and an inner space of the airtight container 31 is formed by an inner container 32 so that a pressure change detection unit 33 as a first pressure change detection unit and a pressure change detection unit as a second pressure change detection unit. It is partitioned into the fluctuation detecting unit 34. Medium container 3
2 is formed of an insulating synthetic resin. Medium container 3
2 and the closed container 31 have a seal member (O
Ring) is provided, and the pressure fluctuation detection units 33, 34 are provided.
Each airtightness is secured.

The pressure fluctuation detector 33 includes a pressure chamber 33A as a first pressure chamber and a pressure chamber 33 as a second pressure chamber.
B, and the pressure chambers 33A and 33B are partitioned by a piezoelectric film 35. Similarly, the pressure fluctuation detection unit 34 has a pressure chamber 34A as a first pressure chamber and a pressure chamber 34B as a second pressure chamber, and the piezoelectric film 35 is provided between these pressure chambers 34A and 34B. It is partitioned.

The piezoelectric film 35 forms a partition wall between the two pressure chambers and receives the pressure due to the fluctuation of the differential pressure between the two pressure chambers based on the pressure fluctuations introduced into the pressure fluctuation detecting portions 33 and 34. Then, it is converted into an electric signal and outputted, and is formed of a film-shaped piezoelectric material. Specifically, for example, a polymeric piezoelectric film such as a polyvinylidene fluoride (PVDF) film is used. Electrodes are formed on both surfaces of the piezoelectric film 35 by depositing a metal such as aluminum. The surfaces of these electrodes are coated with a coating film (not shown) for the purpose of preventing corrosion.

The piezoelectric film 35 has a piezoelectric film main body 35a, and the peripheral edge portion 35b of the piezoelectric film main body 35a is grasped from both sides by cylindrical tubular support members 36A and 36B and the pressure chamber 33A and 33B and between the pressure chambers 34A and 34B, respectively. The cylindrical support members 36A and 36B are the pressure fluctuation detection unit 3
It is arranged along the inner peripheral surface of each of the parts 3, 34. A seal member (O-ring) (not shown) is provided between the piezoelectric film 35 and the cylindrical support members 36A and 36B, and is provided between the pressure chamber 33A and the pressure chamber 33B and between the pressure chamber 34A and the pressure chamber 34A. Airtightness with 34B is secured respectively.

FIG. 4 shows the sectional shape of the piezoelectric film 35 along the radial direction. In the vicinity of the peripheral edge portion 35b of the piezoelectric film main body 35a, for example, a single fold portion 35c is formed along the peripheral edge portion 35b. The fold portion 35c is curved so as to project upward from the surface of the piezoelectric film body 35a (that is, from one surface (surface of one polarization polarity) to the other surface (surface of the other polarization polarity). Has been formed.

The planar shape of the fold portion 35c is circular (ring-shaped) so as to be concentric with the peripheral edge portion 35b of the piezoelectric film 35 because the planar shape of the piezoelectric film body 35a is circular in this embodiment. Is formed in. Here, the piezoelectric film 35 is formed by punching out a sheet-shaped piezoelectric material into a shape (circular shape in this embodiment) of an appropriate size. 34
As described above, it is warped into a spherical shape as shown in FIG. 4 before being mounted inside.

FIG. 5 shows the cylindrical support members 36A and 36B taken out. The cylindrical support member 36A is the pressure chamber 3
3A and the pressure chamber 34A respectively, and the cylindrical support member 3
6B constitutes each of the pressure chamber 33B and the pressure chamber 34B. Opposing surfaces of the cylindrical support members 36A and 36B are gripping surfaces 36a and 36b, respectively.
Each of a and 36b is a flat surface that is substantially parallel to the arrangement direction of the piezoelectric film 35.

The piezoelectric film 35 of this embodiment has increased flexibility due to the formation of the fold portion 35c, and when the peripheral edge portion 35b is gripped by the cylindrical support members 36A and 36B, it is indicated by a chain double-dashed line in FIG. As shown, the warped state of the piezoelectric film main body 35a due to punching is corrected, and the piezoelectric film main body 35a is stretched substantially horizontally as a whole. The piezoelectric film 35 is connected to a circuit board 40, which will be described later, via a lead wire (not shown).

3, the pressure chamber 33A of the pressure fluctuation detection unit 33 and the pressure chamber 34A of the pressure fluctuation detection unit 33 are provided in the pressure guiding hole 32A formed in the middle container 32 and the closed container 31. Through the formed pressure guide port 31A,
The pressure guide holes 26 formed in one of the feedback channels 21 of the flowmeter main body 10 are communicated with each other, and pressures corresponding to the flow rates of fluids flowing through the feedback channels 21 are introduced.

The pressure chamber 33B of the pressure fluctuation detecting unit 33 and the pressure chamber 34B of the pressure fluctuation detecting unit 33 are connected via a pressure guiding hole 32B formed in the middle container 32 and a pressure guiding port 31B formed in the closed container 31. , The pressure guide holes 27 formed in the other feedback flow path 22 of the flowmeter body 10 are respectively communicated, and the pressures corresponding to the flow rates of the fluids flowing in the other feedback flow paths 22 are introduced. ing. That is, the pair of feedback flow paths 21,
Due to the fluid fluctuation of the fluid alternately flowing through 22, the differential pressure between the pressure chamber 33A and the pressure chamber 33B in the pressure fluctuation detection unit 33 and the differential pressure between the pressure chamber 34A and the pressure chamber 34B in the pressure fluctuation detection unit 33 varies. As a result, the piezoelectric film 35 vibrates around the central portion.

The pressure fluctuation detectors 33 and 34 have the same size, and the piezoelectric films 35 are arranged in parallel with each other, so that the pressure of the fluid flowing through one of the feedback channels 21 is introduced at the same time. Pressure chamber 33A and pressure chamber 34
The position A is set so that the vertical positions of the piezoelectric film 35 are opposite to each other. That is, in this embodiment, the pressure chamber 33A is set above the piezoelectric film 35, and the pressure chamber 34A is set below the piezoelectric film 35. Further, the pressure chamber 33B and the pressure chamber 34B into which the pressure of the fluid flowing through the other feedback flow channel 22 is simultaneously introduced.
The relationship between B and the piezoelectric film 35 is similar to the relationship between the pressure chamber 33A and the pressure chamber 34A. The two piezoelectric films 35 are arranged so that the surfaces in the same direction have polarization polarities opposite to each other. That is, the pressure chambers 33A, 34
A faces one surface (one polarization surface) of each piezoelectric film 35, and the pressure chambers 33B and 34B respectively face the other surface (other polarization surface) of each piezoelectric film 35. .

A space 31C defined by an inner container 32 is provided in the closed container 31. Space part 31C
A circuit board 40 for detecting the electric signal output from the above-mentioned piezoelectric film 35 is provided therein. The circuit board 40 is fixed to the inner container 32 by a lead screw 41.

FIG. 6 shows a concrete circuit configuration of the circuit board 40. On the circuit board 40, amplification circuits 45A and 45B for amplifying the electric signals output from the piezoelectric films 35 of the pressure fluctuation detection units 33 and 34, and amplifications output from the amplification circuits 45A and 45B, respectively. Signal detection circuits 42A and 42 for respectively detecting signals
B, an adding circuit 43 for adding the outputs of the signal detecting circuits 42A and 42B, and a frequency of fluid vibration based on the output of the adding circuit 43 (that is, the fluid alternately flows through the pair of feedback flow paths 21 and 22). An arithmetic circuit 44 for arithmetically operating a switching frequency that flows in (i.e., also called a fluidic transmission frequency).

The output end of the arithmetic circuit 44 is connected to the input end of the flow rate calculating section 60 shown in FIG. 1, and outputs the calculated frequency signal to the flow rate calculating section 60.

The fluid vibration detecting sensor 30 having such a structure is manufactured as follows. First, when the piezoelectric film main body 35a is formed by punching out a sheet-shaped piezoelectric material into a shape (circular shape) having an appropriate size, the piezoelectric film main body 35a becomes warped as described above. Then, the peripheral edge portion 35 of the piezoelectric film main body 35a is formed by pressure molding.
A fold portion 35c is formed near b. After that, the piezoelectric film 3
Electrodes are formed by vapor-depositing metal on both surfaces of 5.

Then, the peripheral portion 3 of the piezoelectric film body 35.
5b is attached from both sides so as to be sandwiched by the gripping surfaces 36a and 36b of the cylindrical support members 36A and 36B, and the piezoelectric film 35 is attached.
Are arranged in the pressure fluctuation detection units 33 and 34, respectively.

At this time, in this embodiment, the piezoelectric film main body 35 is used.
Since the fold portion 35c is formed in a, this fold portion 35c
This increases the flexibility of the piezoelectric film 35 as a whole. Therefore, the piezoelectric films are formed on the cylindrical support members 36A and 36B formed so that the gripping surfaces 36a and 36b are flat surfaces substantially parallel to the arrangement direction (horizontal direction) of the piezoelectric film 35. 35 can be easily attached. That is,
Piezoelectric film 3 after punching the contact surface with piezoelectric film 35
5 does not need to be an inclined surface corresponding to the shape of the cylindrical support members 36A and 36B, so that the cylindrical support members 36A and 36B can be easily machined and the piezoelectric film 35 can be held in a horizontal state without difficulty. Since it can be attached to the supporting members 36A and 36B, the attaching work is also simplified. Therefore, there is no variation in the attachment state (tension or the like) of the two piezoelectric films 35 in the pressure fluctuation detection units 33 and 34.

Next, the operation of the fluidic flow meter according to this embodiment will be described.

First, when the fluidic flowmeter does not receive the fluid, the fluid does not flow through the pair of feedback flow paths 21 and 22 of the flowmeter main body 10, and the pressure chamber 33A of the fluid vibration detecting sensor 30 34A and pressure chamber 33
The room pressures of B and 34B do not change. Therefore, in this state, the piezoelectric film 35 does not receive the differential pressure,
As shown in FIG. 3, the piezoelectric film 35 maintains an equilibrium state (hereinafter, referred to as an initial state).

When the fluidic flowmeter receives the fluid, the fluid received from the inlet portion 11 of the flowmeter body 10 enters the nozzle portion 14 through the fluid flow path 13. The fluid that has passed through the nozzle portion 14 becomes a jet stream and is jetted from the jet outlet 14. The fluid ejected from the ejection port 14 alternately flows through the pair of feedback channels 21 and 22.

When the fluid flows through one of the feedback flow paths 21, the pressure inside the pressure chamber 33A of the pressure fluctuation detecting unit 33 and the pressure inside the pressure chamber 34A of the pressure fluctuation detecting unit 34 become lower than in the initial state. On the other hand, the room pressure of each of the pressure chamber 33B of the pressure fluctuation detection unit 33 and the pressure chamber 34B of the pressure fluctuation detection unit 34 is the same as that in the initial state. Therefore, in the pressure fluctuation detection units 33 and 34, the piezoelectric film 35 is displaced toward the pressure chambers 33A and 34A side (that is, in the opposite directions) by the pressure difference.

On the contrary, when the fluid flows through the other feedback flow path 22, the pressure inside the pressure chamber 33B on the side of the pressure fluctuation detection unit 33 and the pressure chamber 34B on the side of the pressure fluctuation detection unit 34 becomes lower than in the initial state. . On the other hand, the pressure chamber 33A,
Since the room pressure in 34A is the same as in the initial state, the piezoelectric films 35 are displaced toward the pressure chambers 33B and 34B (that is, in the opposite directions). Thereafter, the same operation causes the piezoelectric film 35 to vibrate up and down in response to fluid vibration.

In response to such vibration of the piezoelectric film 35,
An electric signal is output from the two piezoelectric films 35. The electric signals output from the two piezoelectric films 35 are respectively amplified by the amplification circuits 45A and 45B to a predetermined magnitude, and then detected by the signal detection circuits 42A and 42B. Then, the signals detected by these signal detection circuits 42A and 42B are output to the addition circuit 43, respectively. The adder circuit 43 includes signal detection circuits 42A and 4A.
After adding the output signals of 2B, the added value is output to the arithmetic circuit 44. The arithmetic circuit 44 is the addition circuit 4
Based on the output of 3, the pair of feedback channels 21, 2
The frequency of fluid vibration of the fluid flowing through 2 (that is, fluidic oscillation frequency) is calculated, and the frequency is output to the flow rate calculation unit 50. The flow rate calculation unit 50 calculates the flow rate of the fluid flowing through the pair of feedback channels 21 and 22 based on the fact that the fluid vibration of the fluid correlates with the flow rate of the fluid.
The flow rate of the fluid is calculated from the output of 4.

At this time, when mechanical vibration or the like is externally applied in addition to the fluid vibration, each piezoelectric film 35 receives not only the pressure due to the fluid vibration but also the pressure due to the mechanical vibration. Unlike the pressure due to the fluid vibration, the pressure due to the mechanical vibration or the like is applied to the respective piezoelectric films 35 in the same direction. Therefore, a signal increased by an amount corresponding to the pressure due to mechanical vibration from the outside is generated on one piezoelectric film 35, and a signal corresponding to the pressure due to the mechanical vibration from the outside is generated on the other piezoelectric film 35. A signal reduced by that amount is generated.

Here, in the fluid vibration detecting sensor of this embodiment, as described above, the fold portion 35c is formed on the piezoelectric film body 35a.
Is formed and the flexibility of the piezoelectric film main body 35a is increased, the two pressure fluctuation detecting portions 3 are attached at the time of attachment.
It is easy to make the tensions generated in the piezoelectric film 35 equal between 3 and 34. Therefore, the relationship between the pressure applied to the piezoelectric film 35 and the generated electric signal is two piezoelectric films 3.
5 is the same. That is, the amount of increase in the electric signal output from one piezoelectric film 35 and the amount of decrease in the electric signal output from the other piezoelectric film 35 are the same when they are affected by mechanical vibration from the outside. become. Therefore, by adding the electric signals respectively detected by the signal detection circuits 42A and 42B by the addition circuit 43, it is possible to eliminate the influence of mechanical vibration from the outside, thereby improving the detection accuracy.

In this embodiment, the piezoelectric film body 3
Although one fold portion 35c is formed for 5a, as shown in FIG. 7, a plurality of fold portions 35c may be formed so as to be concentric with the peripheral edge portion 35b of the piezoelectric film body 35a. Good.

The protruding directions of the plurality of folds 35c are not limited to the same direction, and they may be projected in different directions. Then, in this case, as shown in FIG. 8, a fold portion 35d protruding in the opposite direction to the fold portion 35c may be formed adjacent to the fold portion 35c, and as shown in FIG. Thus, the folds 35d may be formed so as to be separated from the folds 35c by a predetermined distance. Furthermore, FIG.
As shown in FIG. 5, a plurality of combinations (two in the figure) of the above-mentioned folds 35c and folds 35d may be formed.

As described above, by forming the pleats 35c and the pleats 35d projecting in opposite directions with respect to the piezoelectric film 35a, the piezoelectric film 35 is deformed in one direction and in the other direction. The mechanical characteristics can be made the same as in the case described above, and as a result, it is possible to more effectively eliminate the effects of in-phase pressure fluctuation, external mechanical vibration, and the like.

The present invention is not limited to the above embodiments, but can be variously modified within the scope of equivalents of the present invention. For example, in the above embodiment, the two piezoelectric films 35 are arranged side by side so that the planes in the same direction have opposite polarization polarities, but they may be arranged side by side so that the planes in the same direction have the same polarization polarity. Good. In the above embodiment, the piezoelectric film 3
Although the planar shape of 5 is circular, other shapes may be adopted depending on the shape of the pressure chamber.

[0052]

As described above, according to the piezoelectric film of any one of claims 1 to 5, at least one fold is provided along the peripheral edge of the piezoelectric film main body. Even if the piezoelectric film body is formed in a warped state by punching, the folds increase the flexibility of the piezoelectric film body as a whole. Therefore, there is an effect that the work of mounting the fluid vibration detection sensor on the cylindrical support becomes easy, and the mounting state such as tension applied to the piezoelectric film main body can be made the same.

Further, according to the fluid vibration detecting sensor of the sixth aspect, since the piezoelectric film of the present invention having increased flexibility is used, the contact surface of each of the pair of cylindrical supporting members with the piezoelectric film is
Even if the piezoelectric film is formed so as to have a flat surface that is substantially parallel to the arrangement direction of the piezoelectric film, the piezoelectric film can be easily attached to the tubular support member. That is, the contact surface with the piezoelectric film does not have to be an inclined surface corresponding to the shape of the piezoelectric film after punching, and therefore, the work of working the cylindrical support member is easy and the piezoelectric film There is an effect that the attachment work to the cylindrical support member is also simplified.

Further, according to the fluid vibration detecting sensor of the seventh aspect, between the first pressure chamber and the second pressure chamber in each of the first pressure fluctuation detecting section and the second pressure fluctuation detecting section. Since the piezoelectric film of the present invention is arranged,
The attachment state (tension, etc.) of the two piezoelectric films is uniform, that is, their mechanical characteristics are uniform, and it is possible to sufficiently eliminate the effects of in-phase pressure fluctuations and external mechanical vibrations. As a result, the accuracy of fluid vibration detection is improved compared to the conventional case.

In particular, the fluid vibration detection sensor according to claim 3
When the described piezoelectric film is used, since the folds are formed so as to project from both sides of the piezoelectric film body, there is no difference in mechanical characteristics between the two surfaces of the piezoelectric film body. Therefore, it is possible to more effectively eliminate the influence of pressure fluctuations in the same phase, mechanical vibration from the outside, etc., and the detection accuracy is further improved.

Further, according to the fluidic flowmeter of the eighth aspect, since the fluid vibration detection sensor of the present invention having improved fluid vibration detection accuracy is used, the flow rate detection accuracy is improved. .

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic configuration of a fluidic flow meter according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a configuration of a flow meter main body in the fluidic flow meter shown in FIG.

FIG. 3 is a cross-sectional view showing a configuration of a fluid vibration detection sensor in the fluidic flow meter shown in FIG.

4 is a cross-sectional view showing a piezoelectric film of the fluid vibration detection sensor shown in FIG.

FIG. 5 is an exploded perspective view showing a tubular support member of the fluid vibration detection sensor shown in FIG.

6 is a block diagram showing a circuit configuration of the fluid vibration detection sensor shown in FIG.

7 is a cross-sectional view showing a modified example of the piezoelectric film shown in FIG.

8 is a cross-sectional view showing another modification of the piezoelectric film shown in FIG.

9 is a cross-sectional view showing another modification of the piezoelectric film shown in FIG.

10 is a cross-sectional view showing another modification of the piezoelectric film shown in FIG.

FIG. 11 is a cross-sectional view showing a configuration of a conventional piezoelectric film.

FIG. 12 is a cross-sectional view showing a state before attachment of a conventional piezoelectric film to a tubular support member.

FIG. 13 is a cross-sectional view showing a state after attachment of a conventional piezoelectric film to a cylindrical support member.

[Explanation of symbols]

 10 Flowmeter main body 11 Inlet part 14 Nozzle part 21, 22 Feedback flow path 30 Fluid vibration detection sensor 33, 34 Pressure fluctuation detection part 33A, 34A Pressure chamber (first pressure chamber) 33B, 34B Pressure chamber (second pressure) Chamber 35 Piezoelectric film 35a Piezoelectric film main body 35c, 35d Folds 36A, 36B Cylindrical support members 36a, 36b Gripping surface 50 Flow rate calculation unit

Claims (8)

[Claims] 1. A piezoelectric film formed by punching out a sheet-shaped piezoelectric material, comprising: a piezoelectric film main body, a peripheral surface of the piezoelectric film main body, and a surface of the piezoelectric film main body. A piezoelectric film having at least one fold portion curvedly formed so as to project from the piezoelectric film. 2. The piezoelectric film according to claim 1, wherein the piezoelectric film has a plurality of folds, and these folds both project from the surface of the piezoelectric film main body in the same direction. 3. The piezoelectric film according to claim 1, wherein the piezoelectric film has a plurality of folds, and the adjacent folds of the folds protrude in different directions from each other on the surface of the piezoelectric film body. 4. The piezoelectric film according to claim 2 or 3, wherein adjacent folds of a plurality of folds are continuously provided. 5. The piezoelectric film according to claim 2 or 3, wherein adjacent folds among a plurality of folds are provided at a fixed distance from each other. 6. A fluid vibration detection sensor for detecting a fluid vibration based on a differential pressure fluctuation between a pair of pressure chambers arranged opposite to each other, the fluid vibration detection sensor being disposed between the pair of pressure chambers. The piezoelectric film according to any one of claims 1 to 5, which vibrates in response to fluctuations in differential pressure between the two pressure chambers, and contact surfaces of the piezoelectric film and the piezoelectric film are arranged in a direction in which the piezoelectric film is arranged. It is formed to be a flat surface that is substantially parallel to
The fluid vibration detection sensor according to claim 1, further comprising a pair of cylindrical support members that grip the peripheral portion of the piezoelectric film from both sides by these flat surfaces. 7. A first pressure fluctuation detecting unit having a first pressure chamber and a second pressure chamber, and a first pressure chamber and a second pressure chamber of the first pressure fluctuation detecting unit. A second pressure fluctuation detection unit having a first pressure chamber and a second pressure chamber whose positional relations are set to be opposite to each other, and one of the two flow paths in which the fluid flows alternately The pressure based on the fluid vibration is introduced into the first pressure chambers of the first pressure fluctuation detection unit and the second pressure fluctuation detection unit, and the pressure based on the fluid vibration of the other channel is applied to the first pressure chamber. A fluid vibration detection sensor adapted to be introduced into a second pressure chamber of the fluctuation detection unit and the second pressure fluctuation detection unit, wherein the first pressure fluctuation detection unit and the second pressure fluctuation detection unit are respectively In any one of claims 1 to 5, between the first pressure chamber and the second pressure chamber. Fluid vibration detection sensors which is characterized in that is provided a piezoelectric film according to one. 8. An inlet portion for receiving a fluid, a nozzle portion for passing the fluid received from the inlet portion to generate a jet flow, and a pair of feedbacks for guiding the fluid passing through the nozzle portion to the jet outlet side of the nozzle portion. A fluid vibration detection sensor according to claim 7, which detects a fluid vibration by introducing a fluid that alternately flows through the flow passage and the pair of feedback fluid passages, and the fluid vibration detection sensor based on the fluid vibration detected by the fluid vibration detection sensor. A fluidic flow meter, comprising: a flow rate calculating means for calculating a flow rate of a fluid received from an inlet portion.