JPH0972803A - Fluctuating pressure detection sensor - Google Patents

Abstract

(57) 【Abstract】 PROBLEM TO BE SOLVED: To use an amplifier and an AD without requiring a power source for a sensor unit
Provided is a fluctuating pressure detection sensor having a simple structure that does not require an auxiliary circuit such as a converter. SOLUTION: A thin film 62 formed of a material having a high magnetic permeability is stretched and arranged in the center of a container body 61, and the thin film 6 is formed.
The permanent magnet 63 is arranged so as to sandwich 2 between the two magnetic poles. The air chambers 68 and 69 partitioned by the thin film 62 of the container 61 are connected to pressure guiding holes (not shown) of the fluidic element by pressure guiding tubes 51 and 52, respectively. The fluidic oscillation in the fluidic element causes a pressure difference between the pressure guiding tubes 51 and 52 to vibrate the thin film 62, and this vibration causes a magnetic field change in the vicinity of the thin film 62. Magnetic sensor 65 disposed near the thin film 62
Detects this magnetic field change and outputs a high voltage pulse generated by the large Barkhausen effect. This voltage pulse is counted to obtain the fluidic oscillation frequency and converted into a flow rate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluctuating pressure detection sensor for detecting a pressure fluctuation of a fluid such as gas, and more particularly to a fluctuating pressure detection sensor used for detecting a fluidic oscillation in a fluidic flow meter.

[0002]

2. Description of the Related Art A fluidic flowmeter is known as a flowmeter used for gas meters and the like. This flowmeter forms a flow path expansion part by a pair of side walls on the downstream side of a nozzle that generates a jet flow, and a return guide provided on the outer side of the side wall allows the fluid that has passed through the nozzle to flow to the outer side of each side wall. A pair of feedback flow paths that lead to the nozzle outlet side are formed along the flow path, and the frequency of a phenomenon in which the fluid that has passed through the nozzle alternately flows through the pair of feedback flow paths (hereinafter referred to as fluidic oscillation) It is a flow meter that utilizes the relationship with the flow rate.

FIG. 7 shows an overall schematic configuration of a conventional fluidic flow meter. This flow meter includes a fluidic element 100 configured as described above, a piezoelectric film sensor 110 that detects fluidic oscillation, and an arithmetic circuit 120 that calculates a flow rate based on the output of the piezoelectric film sensor 110.
It is constituted by. The piezoelectric film sensor 110 is provided with a piezoelectric film 114 arranged so as to vibrate according to a pressure difference between gas pressures 112 and 113 introduced from two pressure guide holes provided on the ejection port side of the nozzle, and the piezoelectric film 114. Amplifier (AMP) that amplifies a weak voltage generated by the vibration of the membrane 114
115 and an analog / digital converter (AD) for converting the analog output of the amplifier 115 into a digital pulse.
C) 116. Then, the piezoelectric film sensor 11
0 detects the differential pressure between the two pressure guiding holes, and detects the fluidic oscillation based on the change in the differential pressure.
The oscillating frequency (pulse) is counted by the arithmetic circuit 120 to calculate the flow rate.

[0004]

As described above, conventionally, in order to detect the fluidic oscillation in the fluidic flowmeter, in addition to the piezoelectric film sensor, an amplifier, an AD converter, etc. are required, and the piezoelectric film sensor is I needed a power supply. Therefore, there is a problem that the structure and the circuit configuration are complicated.

The present invention has been made in view of the above problems, and an object thereof is a fluctuating pressure detection sensor having a simple structure that does not require a power source for a sensor unit and does not require an auxiliary circuit such as an amplifier or an AD converter. To provide.

[0006]

A fluctuating pressure detection sensor according to a first aspect of the present invention comprises a thin film which is formed of a material having a high magnetic permeability and which is stretched and arranged in a magnetic field and which vibrates in response to a change in fluid pressure. A magnetic sensor is provided in the vicinity of the thin film and detects a magnetic field change caused by the vibration of the thin film.

In this fluctuating pressure detection sensor, the thin film vibrates in response to fluctuations in the fluid pressure to change the magnetic field in the vicinity thereof, and this change is detected by the magnetic sensor.

The fluctuating pressure detection sensor according to a second aspect is the fluctuating pressure detection sensor according to the first aspect, wherein the magnetic field is formed by a magnet having magnetic poles facing each other, and the thin film is formed between the magnetic poles facing each other. It is configured to be arranged in. With this fluctuating pressure detection sensor,
Since the magnetic field strength can be increased, the detection sensitivity becomes good.

A fluctuating pressure detecting sensor according to a third aspect is the fluctuating pressure detecting sensor according to the second aspect, wherein the magnetic sensor is arranged in a cavity formed in one of the magnetic poles. Is. In this fluctuating pressure detection sensor, since the sensor is arranged in the region where the magnetic field change is the largest, it is possible to detect a minute magnetic field change.

A fluctuating pressure detection sensor according to a fourth aspect is the fluctuating pressure detection sensor according to the first aspect, wherein the magnetic field is formed by a bar magnet and the thin film is formed by:
The bar magnet is arranged so as to face one of the magnetic poles. This fluctuating pressure detection sensor has a simple structure.

According to another aspect of the present invention, there is provided a fluctuating pressure detecting sensor, which is provided with a magnetic thin film which vibrates in response to a change in fluid pressure, and which is arranged in the vicinity of the thin film and detects a magnetic field change caused by the vibration of the thin film. And a magnetic sensor.

In this fluctuating pressure detection sensor, the magnetic thin film vibrates according to the fluctuation of the fluid pressure, so that the magnetic field of the thin film itself changes, and the change is detected by the magnetic sensor.

A fluctuating pressure detection sensor according to a sixth aspect is the fluctuating pressure detection sensor according to any one of the first to fifth aspects, wherein the magnetic sensor is a sensor utilizing the large Barkhausen effect. It is a thing.

In this fluctuating pressure detection sensor, since the output signal is a digital pulse having a large wave height, an auxiliary circuit such as an amplifier or an analog / digital converter is unnecessary.

[0015]

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

FIG. 1 shows a cross section of the essential part of a fluidic element to which a fluctuating pressure detection sensor according to an embodiment of the present invention is applied. The present embodiment is an example applied to a fluidic flow meter used as a gas meter.

As shown in FIG. 1, this fluidic element comprises a main body 10 having an inlet portion 11 for introducing gas and an outlet portion 12 for discharging gas. A partition wall 13 is provided in the main body 10. A gas flow path 14 is formed between the partition wall 13 and the inlet portion 11, and a gas flow path 15 is formed between the partition wall 13 and the outlet portion 12. An opening 16 is provided in the partition wall 13, and a shutoff valve 17 capable of closing the opening 16 is provided in the gas flow path 14.
Is provided. A solenoid 18 is provided outside the main body 10.
Is fixed, and the plunger 19 of this solenoid 18
It penetrates the side wall of the main body 10 and is joined to the shutoff valve 17. Plunger 1 between shutoff valve 17 and body 10
A spring 20 is provided around 9 and biases the shutoff valve 17 toward the opening 16.

In the gas passage 15, there is provided a nozzle portion 21 which allows the gas introduced from the inlet portion 11 to pass therethrough and arranges a jet flow. A rectifying member 22 for regulating the flow of gas is provided on the upstream side of the nozzle portion 21.
On the downstream side of the nozzle portion 21, a pair of side walls 23 and 24 that form an enlarged flow path are provided. This side wall 2
A predetermined space is provided between the No. 3 and No. 24, and a first space is provided on the upstream side.
The target 25 and the second target 26 are disposed on the downstream side, respectively. A pair of feedback flow paths 27, 28 are formed outside the side walls 23, 24 to return the gas passing through the nozzle part 21 to the ejection port side of the nozzle part 21 along the outer circumferences of the side walls 23, 24. Guide 29
Are arranged. A return guide 29 is provided between each outlet of the feedback flow paths 27 and 28 and the outlet 12.
A pair of discharge paths 31, 32 are formed by the back surface of the body and the main body 10.
Are formed. In the vicinity of the ejection port of the nozzle portion 21,
Pressure guiding holes 33 and 34 are provided which communicate with a fluctuating pressure detection sensor (described later) for detecting switching of the flow direction of the gas passing through the nozzle portion 21.

Next, the general operation of the fluidic element having the above-mentioned structure will be described. The gas introduced from the inlet part 11 enters the nozzle part 21 through the gas flow path 14, the opening part 16, the gas flow path 15, and the rectifying member 22 in this order. The gas that has passed through the nozzle portion 21 becomes a jet stream and is jetted from the jet outlet. The gas ejected from the ejection port flows along one side wall due to the Coanda effect. Here, first, the side wall 23
Shall flow along. The gas that has flowed along the side wall 23 further passes through the feedback flow path 27, and then the nozzle portion 2
1 is returned to the jet outlet side, passes through the discharge passage 31 and the outlet portion 12
Is more exhausted. At this time, the gas ejected from the nozzle portion 21 is changed in direction by the gas flowing through the feedback flow path 27, and now flows along the other side wall 24. This gas is further returned to the ejection port side of the nozzle portion 21 via the feedback flow path 28, and is discharged from the outlet portion 12 via the discharge passage 32. Then, the direction of the gas ejected from the nozzle portion 21 is changed by the gas flowing through the feedback channel 28, and the gas flows again along the side wall 23 and the feedback channel 27. By repeating the above operation, the gas that has passed through the nozzle portion 21 performs fluidic oscillation that alternately flows through the pair of feedback flow paths 27 and 28.
The frequency (or cycle) of this fluidic oscillation has a correlation with the flow rate (flow velocity), and the frequency increases as the flow rate increases.

FIG. 2 is an enlarged view of a cross section including the pressure guiding holes 33 and 34 and the fluctuating pressure detection sensor in FIG. As shown in this figure, a fluctuating pressure detection sensor 37 is provided outside the bottom of the main body 10. Also,
One ends of pressure guiding pipes 51 and 52 are connected to the pressure guiding holes 33 and 34, respectively. The other ends of the pressure guiding tubes 51, 52 are
It is connected to each pressure introduction port of the fluctuating pressure detection sensor 37. Then, the fluctuating pressure detection sensor 37 detects the difference between the pressure in the pressure guiding hole 33 and the pressure in the pressure guiding hole 34 (hereinafter, simply referred to as differential pressure), and based on the change in the differential pressure, fluidic oscillation. It is designed to detect The pressure guiding tubes 51, 52 and the fluctuating pressure detection sensor 37 are fixed to the case 5 fixed to the outside of the bottom of the main body 10.
5 is covered.

FIG. 3 shows the fluctuating pressure detection sensor 3 in FIG.
7 shows a cross section of No. 7. This fluctuating pressure detection sensor 3
Reference numeral 7 denotes a container body 61 disposed between the pressure guiding pipes 51 and 52 and joined to the pressure guiding pipes 51, 52, and a container body 61 extending substantially over the center of the air chamber formed by the container body 61. The thin film 62 provided and the thin film 6 sandwiching the thin film 62
Two magnetic poles (S pole,
A "C" -shaped permanent magnet 63 having an N pole), a magnetic sensor 65 disposed inside a cavity 64 formed in the N pole side of the permanent magnet 63 in a direction perpendicular to the thin film 62, and a magnetic sensor Output terminal 6 for outputting the output signal from the sensor 65 to the outside
6 is provided.

The thin film 62 is formed on the pressure guiding tube 51 side and the pressure guiding tube 52 side.
The chamber body 61 is divided into two air chambers 68 and 69 having substantially the same volume by being stretched over so as to shut off the other side (so that gases do not flow to each other). The permanent magnet 63 is a container body 61.
Is arranged so as to penetrate through the wall, but the airtightness is maintained at the penetrating portion. The lead wire 70 connecting between the magnetic sensor 65 and the output terminal 66 also penetrates the wall of the container body 61, but airtightness is also maintained in the penetrating portion. The permanent magnet 63 forms a magnetic circuit therein, and N
A magnetic field line extending from the pole to the S pole penetrates the thin film 62 almost vertically. The thin film 62 is formed of a material having a high magnetic permeability, such as iron, and the lines of magnetic force penetrate the thin film 62 without being weakened.

The magnetic sensor 65 utilizes the large Barkhausen effect in which all the magnetization processes are completed by only one domain wall movement, and a detection coil is wound around an iron-based amorphous metal fiber which is a magnetostrictive material. It has a simple structure that is rotated. This sensor causes an irreversible flux reversal called a large Barkhausen jump by giving a weak alternating magnetic field of the earth's magnetic field (0.2 Oersted), and can obtain a high pulse voltage across the coil without a power supply. However, it has an excellent characteristic that the voltage induced in the coil is constant without depending on the changing speed of the magnetic field. For example, when an alternating magnetic field (H _m = 2 oersted) as shown in FIG. 4A is applied, a voltage pulse (e _p = 100 to
300 mV or more) is induced.

Next, the operation of the fluidic flow meter having the above structure will be described.

In the fluidic element shown in FIG. 1, the gas passing through the nozzle portion 21 has a pair of feedback channels 2.
When fluidic oscillation that alternately flows through 7 and 28 occurs, a differential pressure change corresponding to this fluidic oscillation frequency occurs between the pressure guiding tube 51 and the pressure guiding tube 52, and the thin film 62 vibrates accordingly. . Therefore, a magnetic field changes in the vicinity of the thin film 62, which is detected by the magnetic sensor 65 and a high voltage pulse is output from the output terminal 66. The frequency (or cycle) of fluidic oscillation has a correlation with the flow rate (flow velocity), and the frequency increases as the flow rate increases. Therefore, the flow rate can be obtained by counting and converting the voltage pulse from the magnetic sensor 65 by an arithmetic circuit (not shown).

As described above, in this embodiment, the output signal from the magnetic sensor 65 is a digital pulse having a sufficient voltage value.
An auxiliary circuit such as C and a power supply are not required, and a fluctuating pressure detection sensor can be realized with a simple structure. Further, since the thin film 62 and the magnetic sensor 65 can be arranged in non-contact with each other, the thin film 62 has a good gas sealability.

In this embodiment, the magnetic sensor 65 is used.
By providing a circuit such as a voltage follower or a waveform shaper between the operation circuit and the arithmetic circuit, more stable operation can be ensured. Further, in the present embodiment, in order to improve detection sensitivity, the magnetic sensor 65 is provided in the cavity 64 formed in the permanent magnet 63.
Although it is arranged inside, it is not limited to this, and may be arranged near the outside of the permanent magnet 63.

Next, another embodiment of the present invention will be described.

FIG. 5 shows a sectional configuration of a fluctuating pressure detection sensor 38 according to another embodiment of the present invention, which is applied to the fluidic flowmeter shown in FIGS. 1 and 2. Is. Here, the same components as those in FIG. 3 are designated by the same reference numerals, and the description thereof will be omitted.

In this fluctuating pressure detection sensor 38, instead of the "C" -shaped permanent magnet 63 in FIG. 3, a rod-shaped (plate-shaped) permanent magnet 71 is used, and one magnetic pole (N in this case).
A plurality of support members 72 so that the poles) face the thin film 62,
It is fixed by 73 etc. As a result, the magnetic line of force exits the N pole, penetrates the thin film 62 almost vertically, and reaches the S pole. A cavity 74 is bored at a substantially central portion of the permanent magnet 71, and a magnetic sensor 65 is arranged at a minute distance from the thin film 62 therein. Other configurations are the same as those in FIG. 3, and the operation thereof is also the same as that of the fluctuating pressure detection sensor according to the above-mentioned embodiment, and therefore the description thereof is omitted.

Since this fluctuating pressure detection sensor has a simple structure, it is easier to manufacture than the fluctuating pressure detection sensor of FIG.

Next, still another embodiment of the present invention will be described.

FIG. 6 shows a sectional configuration of a fluctuating pressure detection sensor 39 according to another embodiment of the present invention, which is applied to the fluidic flowmeter shown in FIGS. 1 and 2. Is. Here, the same components as those in FIG. 3 are designated by the same reference numerals, and the description thereof will be omitted.

This fluctuating pressure detection sensor 39 uses a magnetic thin film (hereinafter referred to as a magnetic thin film) 81 in place of the thin film 62 in FIG. 3, and does not require a permanent magnet for giving a magnetic field. is there. A magnetic sensor 65 is fixedly mounted on the magnetic thin film 81 near the center thereof by means of supporting members 82, 83 and the like. Other configurations are the same as those in FIG.

When the pressure difference between the pressure guiding tube 51 and the pressure guiding tube 52 is large and the displacement of the magnetic thin film 81 can be set to be large, the permanent magnet can be omitted by making the thin film itself magnetic. It is possible, and the structure is simpler and the manufacturing is easier. However, in this case, in order to secure the sensitivity, it is desirable to dispose the magnetic sensor 65 as close as possible to the magnetic thin film 81 in a range that does not contact the vibrating magnetic thin film 81.

In each of the above embodiments, the case where the present invention is applied to the fluidic flow meter has been described, but it goes without saying that the present invention is not limited to this.

[0037]

As described above, according to the fluctuating pressure detection sensor of the first aspect, the magnetic sensor detects the magnetic field which changes due to the vibration of the thin film in response to the fluctuation of the fluid pressure. There is an effect that the sensor section does not require a power source and an auxiliary circuit such as an amplifier and an AD converter is unnecessary, and the structure is simplified. Further, since the thin film and the magnetic sensor can be arranged in non-contact with each other, the sealing property of the fluid by the thin film becomes good.

Particularly, according to the fluctuating pressure detection sensor of the second aspect, since the magnetic field strength can be increased, there is an effect that the detection sensitivity becomes good.

Further, according to the fluctuating pressure detection sensor of the third aspect, since the magnetic sensor can be arranged in the region where the magnetic field change is the largest, there is an effect that the detection sensitivity becomes better.

According to the fluctuating pressure detection sensor of the fourth aspect, since the structure is simple, there is an effect that the manufacture is easy.

According to the fluctuating pressure detection sensor of the fifth aspect, since it is not necessary to apply a magnetic field from the outside by making the thin film itself magnetic, there is an effect that the structure becomes simpler.

According to the fluctuating pressure detection sensor of the sixth aspect, since the magnetic sensor is composed of a sensor utilizing the large Barkhausen effect, it is possible to obtain a digital pulse having a large wave height as an output signal. Therefore, an auxiliary circuit such as an amplifier and an analog / digital converter, which has been conventionally required, is not required, which is effective in simplifying the structure and reducing the cost.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a main part of a fluidic flow meter to which a fluctuating pressure detection sensor according to an embodiment of the present invention is applied.

FIG. 2 is an enlarged cross-sectional view showing a pressure guiding hole and a fluctuating pressure detection sensor in the flow meter of FIG.

FIG. 3 is a sectional view showing a configuration of a fluctuating pressure detection sensor according to an embodiment of the present invention.

FIG. 4 is a diagram showing characteristics of a magnetic sensor.

FIG. 5 is a sectional view showing a configuration of a fluctuating pressure detection sensor according to another embodiment of the present invention.

FIG. 6 is a sectional view showing a configuration of a fluctuating pressure detection sensor according to still another embodiment of the present invention.

FIG. 7 is a block diagram showing a schematic configuration of a conventional fluidic flow meter.

[Explanation of symbols]

 37, 38, 39 Fluctuating pressure detection sensor 51, 52 Pressure guide tube 61 Container body 62 Thin film 63, 71 Permanent magnet 65 Magnetic sensor 81 Magnetic thin film

Continued Front Page (72) Inventor Shinichi Sato 543-15 Kitano-cho, Hachioji-shi, Tokyo

Claims (6)

[Claims] 1. A thin film which is made of a material having high magnetic permeability and which is stretched and arranged in a magnetic field and vibrates in response to fluctuations in fluid pressure; and a thin film which is arranged in the vicinity of this thin film and is generated by the vibration of the thin film. A fluctuating pressure detection sensor comprising: a magnetic sensor that detects a change in a magnetic field. 2. The fluctuating pressure detection sensor according to claim 1, wherein the magnetic field is formed by a magnet having opposing magnetic poles, and the thin film is disposed between the opposing magnetic poles. 3. The fluctuating pressure detection sensor according to claim 2, wherein the magnetic sensor is provided in a cavity formed in one of the magnetic poles. 4. The fluctuating pressure detection sensor according to claim 1, wherein the magnetic field is formed by a bar-shaped magnet, and the thin film is disposed so as to face one magnetic pole of the bar-shaped magnet. 5. A magnetic thin film that vibrates in response to a change in fluid pressure, and a magnetic sensor that is arranged in the vicinity of the thin film and detects a magnetic field change caused by the vibration of the thin film. Fluctuating pressure detection sensor. 6. The fluctuating pressure detection sensor according to claim 1, wherein the magnetic sensor is a sensor utilizing a large Barkhausen effect.