JPH08145748A - Fluid flowmeter - Google Patents

Abstract

PURPOSE: To provide a fluid flowmeter with high sensitivity and wide flow rate range. CONSTITUTION: This flowmeter has a fluid guide part 9 for guiding a fluid, a flat fluid shielding plate 11 pressed by the restoring force of an elastic body 12 onto the end surface of the fluid guide part, a differential pressure detecting means 13 for detecting the differential pressure between the upstream and downstream of the shielding plate, and a displacement detecting means 16 for detecting the displacement of the shielding plate. The fluid shielding plate is displaced according to flow rate, and the differential pressure between the upstream and downstream of the shielding plate is changed. The flow rate can be detected by the displacement and differential pressure of the shielding plate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluid flow meter for detecting a flow rate of a fluid, and more particularly to a fluid flow meter capable of detecting a minute flow rate and having a wide flow rate detection range.

[0002]

2. Description of the Related Art As a conventional fluid flow meter of this type, a differential pressure type fluid flow meter as shown in FIG. 12 is well known. That is, the orifice 2 is provided in the pipeline 1 through which the fluid flows, the differential pressure generated between the upstream and the downstream of the orifice 2 is detected by the differential pressure gauge 3, and the flow rate of the fluid through the pipeline 1 is detected from this differential pressure. Was. Numerals 4 and 5 denote pressure introduction pipes provided on the upstream side and the downstream side of the orifice 2, respectively, and 6 indicates the direction of fluid flow (see Japanese Patent Laid-Open No. 5-118890).

[0003]

However, in the above structure, the differential pressure generated by the flow of the fluid is proportional to the square root of the flow rate, so that there is a problem that a wide flow rate range cannot be detected accurately. It was

Further, in the low flow rate region, there are problems such as low sensitivity and large error. There is also a problem that the fluid flows backward.

The present invention solves the above-mentioned conventional problems, and an object of the present invention is to provide a fluid flow meter capable of detecting with high accuracy and high sensitivity over a wide detection range from a low flow rate region to a high flow rate region. .

Another object of the present invention is to provide a fluid flow meter in which the fluid does not easily flow backward.

[0007]

In order to solve the above-mentioned problems, the fluid flow meter of the present invention has a fluid introducing portion for introducing a fluid and an end face of the fluid introducing portion pressed by a restoring force of an elastic body. The flat plate-shaped shield plate is provided with differential pressure detection means for detecting the differential pressure between the upstream side and the downstream side of the shield plate, and displacement detection means for detecting the displacement of the shield plate.

Further, the fluid flow meter of the present invention includes a fluid introducing portion for introducing a fluid, and a shield plate made of a flat conductive material pressed against an end surface of the fluid introducing portion by a flat gimbal spring. And a pressure difference detecting means for detecting a pressure difference between the upstream side and the downstream side of the shield plate, and a ring-shaped electrode provided in parallel with the shield plate on the end face of the fluid introducing portion,
The shield plate and the ring-shaped electrode form a capacitance.

Further, the fluid flow meter of the present invention comprises a fluid introducing portion for introducing a fluid, and a shield plate made of a flat conductive material pressed against an end surface of the fluid introducing portion by a flat gimbal spring. And a pressure difference detecting means for detecting a pressure difference between the upstream side and the downstream side of the shield plate, and a ring-shaped electrode provided in parallel with the shield plate on the end face of the fluid introducing portion,
Forming a capacitance with the shield plate and the ring-shaped electrode,
Moreover, a concentric fixed electrode facing the central portion of the shielding plate is provided in the downstream portion of the fluid shielding plate, and the central portion of the shielding plate and the fixed electrode are configured to form a capacitance. is there.

Further, the fluid flow meter of the present invention includes a fluid introducing portion having a central axis for introducing a fluid, and a flat plate which is pressed against an end face of the fluid introducing portion by a restoring force of an elastic body and slides on the central axis. A shielding plate, a differential pressure detecting means for detecting a differential pressure between the upstream side and the downstream side of the shielding plate, and a displacement detecting means for detecting a displacement of the shielding plate.

Further, the fluid flow meter of the present invention is provided with a fluid introducing portion for introducing a fluid, a shield plate pressed against an end face of the fluid introducing portion by a restoring force of an elastic body, and the shield plate on the downstream side. And a displacement detection means for detecting the displacement of the shielding plate, which is held by a piston-shaped bearing and detects the differential pressure between the upstream side and the downstream side of the shielding plate. .

Further, the fluid flow meter of the present invention comprises a fluid introducing portion for introducing a fluid, a shield plate pressed against an end face of the fluid introducing portion by a restoring force of an elastic body, and upstream and downstream of the shield plate. The differential pressure detecting means for detecting the differential pressure with the side and the piston-shaped differential transformer having the shielding plate provided on the downstream side.

Further, the fluid flow meter of the present invention includes a fluid introducing portion for introducing a fluid, a shield plate pressed against an end surface of the fluid introducing portion by a restoring force of an elastic body, and upstream and downstream of the shield plate. The differential pressure detection means for detecting the differential pressure between the side and the side and the piston plate differential transformer provided on the downstream side hold the shielding plate, and the differential transformer has a concave shape.

Further, the differential pressure detecting means of the fluid flow meter according to the present invention is a capacitor formed by adhering two alumina flat plates having an electrode at the central portion in the peripheral portion of the electrode so that the electrodes face each other. And a capacitance type differential pressure detector.

Further, the fluid flowmeter of the present invention comprises a fluid introducing portion for introducing a fluid, and a shield plate made of a flat conductive material pressed against the end surface of the fluid introducing portion by a flat gimbal spring. And a pressure difference detecting means for detecting a pressure difference between the upstream side and the downstream side of the shield plate, and a ring-shaped electrode provided in parallel with the shield plate on the end face of the fluid introducing portion,
Forming a capacitance with the shield plate and the ring-shaped electrode,
Further, a concentric fixed electrode facing the central portion of the shielding plate is provided downstream of the fluid shielding plate, the central portion of the shielding plate and the fixed electrode form a capacitance, and the differential pressure detection is performed. The means is composed of a capacitance type differential pressure detector composed of a capacitor formed by bonding two alumina flat plates having electrodes in the central portion at the peripheral portions of the electrodes so that the electrodes face each other, and The same CR oscillation type detection circuit is used and alternately switched to detect the differential pressure and the displacement.

[0016]

Since the present invention is configured as described above, the fluid force of the fluid is small in the low flow rate region, so that the restoring force of the elastic body presses the shield plate against the end face of the fluid introducing portion for introducing the fluid. The flow path becomes narrow. Further, in the high flow rate region, since the fluid force of the fluid is large, the shielding plate is opposed to the restoring force of the elastic body, and is further separated from the end surface of the fluid introduction portion, and the flow path through which the fluid flows is widened. . As described above, the flow path of the fluid changes depending on the flow rate of the fluid such that the flow path is narrow when the flow rate is low and wide when the flow rate is high. Therefore, even if the flow rate is small, the flow rate can be detected accurately by detecting the pressure difference between the upstream side and the downstream side of the shield plate and the displacement of the shield plate, and the flow rate detection range can be widened.

Further, since the differential pressure and the displacement can be detected at the same time, abnormal displacement, abnormal differential pressure, etc. can be easily detected.

Further, the shield plate is made of a conductive material, and a ring-shaped electrode is formed on the end face of the fluid introducing portion, and a capacitor is formed between the shield plate and the ring-shaped electrode. Therefore, the displacement of the shielding plate can be easily and accurately detected by detecting the capacitance of the capacitor.

Furthermore, since a concentric fixed electrode facing the shielding plate is provided in the downstream portion of the shielding plate, the displacement of the shielding plate is caused by the ring-shaped electrode and the concentric fixed electrode. Since it is detected by and, it can be detected more accurately. Further, since the concentric fixed electrodes are provided in the downstream portion of the shield plate, the fixed electrodes prevent the abnormal displacement of the shield plate even if a fluid force due to an excessive flow rate is applied to the shield plate. To work as.

Further, the present invention has the above-mentioned structure, that is, the shielding plate is pressed by the restoring force of the elastic body against the end face of the fluid introducing portion for introducing the fluid, and the end face has a concave piston shape. Since the piston-shaped bearing operates as an air damper because it is held by a bearing, even if the flow rate of the fluid changes rapidly, the shielding plate does not vibrate and the differential pressure and displacement are stable. And can be detected.

Further, since the present invention has the above-mentioned structure, that is, the shielding plate is pressed against the end face of the fluid introducing portion for introducing the fluid by the restoring force of the elastic body, the case where the fluid flows backward Since the shielding plate is pressed against the end surface of the fluid introducing portion, the fluid does not flow back.

Further, the present invention has the above-mentioned structure, that is, since the differential pressure gauge is constituted by a diaphragm type differential pressure gauge, the diaphragm can be easily enlarged.
You can easily increase the sensitivity. Therefore, it is suitable as a differential pressure gauge for a fluid flow meter that requires detection of a slight differential pressure.

Further, since the present invention has the above-described structure, that is, the capacitance type differential pressure gauge and the capacitance type displacement detecting means are used, the same, for example, CR-oscillation is used. Type capacitance detection circuit can be used, and an efficient circuit configuration can be obtained.

[0024]

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

FIG. 1 shows a cross-sectional view of a fluid flow meter according to the present invention. Reference numeral 8 denotes a fluid flow direction, 9 denotes a cylindrical fluid introduction hole, 10 denotes a frame body that holds the cylindrical fluid introduction hole 9, 11 denotes a circular fluid shield plate, and 12 denotes a frame body 10. Each of the coil-shaped springs holding the fixed circular fluid shield plate 11 is shown. Reference numeral 13 denotes a differential pressure gauge as a differential pressure detecting means. Reference numerals 14 and 15 denote pressure introduction pipes on the upstream side and the downstream side of the fluid shield plate 11, respectively. Reference numeral 16 denotes a laser displacement meter as displacement detecting means for detecting the displacement of the circular fluid shield plate 11.

Next, the operation will be described. The coiled spring 12 is set so as to press the circular fluid shield plate 11 against the end surface of the fluid introduction hole 9 when the fluid does not flow. Therefore, even if pressure is applied so that the fluid flows in the opposite direction, that is, even if the fluid tries to flow backward, the fluid shield plate 11 is pressed against the end surface of the fluid introducing hole 9 and operates so as not to flow backward, thereby preventing backflow. Acts as a valve. Further, when the fluid flows, the fluid shield plate 11 is displaced to a position where the force of the fluid and the coil-shaped spring 12 are balanced. Further, when the fluid flows, a differential pressure proportional to the fluid force is generated. Therefore, by simultaneously detecting the displacement and the differential pressure, the flow rate at that time can be accurately detected. That is, the fluid shield plate is displaced according to the flow rate of the fluid, and the fluid shield plate 11 has a small pressing force when the flow rate is small,
Narrow gap, when the flow rate is large, with a large pressing force,
In addition to forming a wide gap, the differential pressure gauge 13 detects the differential pressure generated in the narrow gap when the flow rate is small, and detects the differential pressure generated in the wide gap when the flow rate is large. Therefore, it is only necessary to detect the differential pressure and the displacement in a relatively narrow range over a wide flow rate range, and it is possible to detect the flow rate with high accuracy and sensitivity.

Since it is practically easy to set the coiled spring 12 to several grams or less, the pressure loss is set to several mmAq to several tens mmAq or less in the flow rate range from a minute flow rate to a large flow rate. In addition, the displacement amount is 0 to 0.
It can be set to about 1 mm.

As described above, the differential pressure generated between the upstream side and the downstream side of the fluid shielding plate 11 and the fluid shielding plate 11
The flow rate at that time can be easily and accurately detected from the displacement amount of.

In FIG. 2, when the spring constant of the spring 12 on the coil is set to 1 g / mm and the inner diameter of the fluid introducing hole 9 is set to 20 mm, the flow rate of air (mL / min) and the differential pressure (mmAq). , And the relationship with the displacement (mm). In the figure, the horizontal axis represents the logarithmic value of the air flow rate (mL / min),
The vertical axis on the left side shows the differential pressure (mmAq), and the vertical axis on the right side shows the displacement (mm). The solid line 17 shows the relationship between the air flow rate and the differential pressure, and the broken line 18 shows the relationship between the air flow rate and the displacement. From a minute flow rate range of several mL / min to a large flow rate range of several tens L / min, a differential pressure of 0 to 6 mmAq, 0 to 1.0 m
It shows that it can be detected by the displacement in the range of m. Therefore, if the differential pressure gauge 13 detects a pressure in the range of 0 to 6 mmAq and the displacement gauge 16 detects a displacement in the range of 0 to 1.0 mm, the flow rate of several mL / min to several tens of micrometer is obtained. L
It shows that the flow rate up to the large flow rate range of / min can be detected. As shown in the figure, if the fluid shield plate is displaced by the flow rate, and a differential pressure in a narrow range is detected,
It can be seen that a wide range of flow rates can be detected.

FIG. 3 shows another embodiment of the present invention.
(A) shows sectional drawing of a fluid flowmeter. Fluid shield 11
Are horizontally held by a flat gimbal spring 19. FIG. 3B shows a plan view of the circular flat gimbal spring 19. The fluid shield plate 11 at the center is supported by a gimbal spring 19 having a ring shape.
9 is fixed to the frame body 10. Note that the ring-shaped spring portions are connected by connecting portions 20 that are orthogonal to each other.
With such a configuration, when the flow rate of the fluid is changed, the fluid shield plate 11 is displaced without tilting while being parallel to the end surface of the fluid introduction hole 9. By detecting the differential pressure at that time by the differential pressure detecting means 13, the flow rate of the fluid can be detected with higher accuracy and reproducibility.

It should be noted that the contact surface between the end surface of the fluid introduction hole 9 and the fluid shield plate 11 should be rough so as not to be in close contact with the reproducibility in the low flow rate range.

FIG. 4 shows another embodiment of the present invention, in which the fluid shield plate 11 is made of a conductive material and a ring-shaped electrode 21 is provided on the end face of the fluid introduction hole 9 in parallel with the fluid shield plate 11. FIG. 3 shows a cross-sectional view of a fluid flow meter configured as described above. Therefore, the fluid shield plate 11 and the ring-shaped electrode 21 form a capacitor. By detecting the capacitance of this capacitor, the displacement of the fluid shield plate 11 supported by the gimbal spring 19 can be detected. Further, the fluid shielding plate 11 is
Since the fluid is displaced while maintaining the end face of the fluid introduction hole 9 horizontal, the fluid shield plate 11 and the ring-shaped electrode 21 come into contact with each other when the fluid is not flowing, and the fluid shield plate 11
Since the ring-shaped electrode 21 and the ring-shaped electrode 21 are short-circuited, zero flow rate can be easily detected. Therefore, in this case, the differential pressure gauge 13
When a differential pressure equal to or higher than a certain value is observed, it is possible to detect whether the differential pressure gauge 13 is abnormal or whether the fluid shield plate 11 is abnormally fixed or adhered to the ring-shaped electrode 21. , Can detect abnormalities. In addition, the abnormal state can be detected from the relationship between the differential pressure and the displacement that are simultaneously detected.

Further, since the zero flow rate can be easily detected by the contact of the electrodes, the differential pressure gauge 13 can be calibrated.

FIG. 5 shows another embodiment of the present invention, which is a concentric fixed electrode 22 fixed to the frame body 10 facing the central portion of the fluid shield plate 11 on the downstream side of the fluid shield plate 11. The sectional view of the flowmeter provided with is shown. The displacement of the fluid shielding plate 11 is caused by the ring-shaped electrode 21 and the concentric fixed electrode 22.
Since it is detected by and, it can be detected more accurately. That is, the sum of the distance between the fluid shield plate 11 and the ring-shaped electrode 21 and the distance between the fluid shield plate 11 and the concentric fixed electrode 22 is always constant. For example, instability of the detection circuit or the like can be eliminated, and the displacements of the detection circuits can be detected constantly with high accuracy.

Further, since the concentric fixed electrodes are provided in the downstream portion of the shield plate, the fluid shield plate 11 corresponds to the fixed electrode even if a fluid force due to an excessive flow rate is applied to the shield plate. Since it can be displaced only up to this point, the fixed electrode acts as a stopper for the abnormal displacement of the shield plate. For this reason, the gimbal spring 19 is not excessively displaced during use to exceed the elastic limit and the flow rate becomes inaccurate.

It is also possible to provide a large number of minute holes on the electrode surface of the concentric fixed electrode and to provide the holes in the fluid introduction hole 9 on the upstream side of the fluid shield plate 11.

FIG. 6 shows another embodiment of the present invention, in which the fluid shield plate 11 is vertically moved along a central axis 24 supported by a beam-shaped support 23 fixed to the inner wall of the fluid introduction hole 9. It is configured to be displaced to. In this case, the fluid flows between the fluid introduction hole 9 and the central shaft 24, and becomes a fluid with little turbulence over a wide flow rate range, and the flow rate can be accurately detected. In addition, even if there is a sudden change in the flow rate, the fluid shield plate 11 will be displaced vertically along the central axis 24 while maintaining parallel to the end face of the fluid introduction hole without tilting, and the followability to the change in flow rate will be high. As well as the accuracy.

FIG. 7 shows another embodiment of the present invention, in which a center rod 25 fixed to the fluid shield plate 11 is supported by a piston-shaped guide 26 provided on the downstream side. In this case as well, the fluid shield plate 11 is displaced while always being parallel to the end surface of the fluid introduction hole 9.

The coil spring 12 can be formed in the piston-shaped guide 26, and a more compact structure can be obtained. Further, in this case, since the center rod 25 and the piston-shaped guide 26 are not directly exposed to the fluid, there is no clogging due to dust or the like, and the structure has excellent durability.

FIG. 8 shows another embodiment of the present invention, in which a center rod 25 fixed to the fluid shield plate 11 is supported by a piston-shaped differential transformer 27 provided on the downstream side.
In this case as well, the fluid shield plate 11 is displaced while always being parallel to the end surface of the fluid introduction hole 9. The displacement of the fluid shield plate 11 is detected by the differential transformer 27. Therefore, the displacement in a wide range can be detected more accurately and easily. Further, if the position of the end face of the differential transformer 27 is matched with the maximum displacement of the fluid shield plate 11, it can be operated as a stopper for the abnormal displacement of the fluid shield plate 11 as described above.

The coil spring 12 is replaced by the differential transformer 2
It is also possible to configure within 7, and a more compact configuration can be achieved. Further, in this case, since the center rod 25 and the differential transformer 27 are not directly exposed to the fluid, there is no clogging due to dust or the like, and the structure has excellent durability.

FIG. 9 shows another embodiment of the present invention, which is a center rod 25 fixed to the fluid shield plate 11 and a differential transformer 27.
And the sealing plate 28 is attached to the end face of the differential transformer 27. Therefore, the differential transformer 27 also operates as an air damper. Therefore, the fluid shielding plate 11 does not vibrate even when the flow rate changes rapidly, and the flow rate can be detected stably by following the flow rate change.

Next, FIG. 10 shows an electrostatic capacitance type differential pressure gauge which is suitable for this type of fluid flow meter and which can be constructed for low differential pressure detection. The differential pressure gauge 13 has two diameters of about 30.
It is composed of disc-shaped alumina plates 29 and 30 of mm. The plate thickness of the upper alumina, which operates as the pressure detection unit (diaphragm), was about 0.050 mm, and the plate thickness of the lower alumina as the base was about 0.600 mm. An upper electrode 31 and a lower electrode 32 made of a circular conductive thin film having a diameter of about 15 mm are formed in the center of each and face each other to form a capacitance. The peripheral portions of the alumina plates 29 and 30 are adhered by an adhesive glass 33. Adhesive glass 33
The inner diameter was about 24 mm, the width was about 2 mm, and the height was about 50 μm. Upstream pressure introducing pipe 14 and alumina plate 2
9 and between the downstream pressure introducing pipe 15 and the alumina plate 3
Between 0 and 0, each is adhered and sealed with an appropriate adhesive, for example, an epoxy adhesive. Reference numeral 34 denotes a through hole provided in the lower alumina plate 30, which is provided so that the pressure on the downstream side is transmitted between the upper alumina plate 29 and the lower alumina plate 30. Therefore, the differential pressure generated between the upstream side and the downstream side of the fluid shield plate 11 is applied to the upper alumina plate 29, and the central portion of the upper alumina plate 29 acts so as to be deformed toward the lower alumina plate 30. To do. In this way, the capacitance formed by the upper electrode 31 and the lower electrode 32 changes due to the pressure difference. By detecting this change in capacitance, the differential pressure applied to the upper alumina plate 29 can be detected. From this change in capacitance, from a minute differential pressure of about 0.01 mmAq to about 50 mmA
It was possible to easily and accurately detect a large differential pressure up to q. Since the diameters of the alumina plates 29 and 30 can be further increased, the sensitivity can be further increased, which is optimal for this type of differential pressure gauge.

If the differential pressure detecting means is of the electrostatic capacitance type as described above and the displacement detecting means of the fluid shield plate is also of the electrostatic capacitance type as described above, the same, for example,
It is possible to detect using one CR-oscillation circuit as shown in FIG. In the figure, R1 and R2 are resistance elements, and C1 and C2 are capacitor elements. Reference numeral 35 denotes an inverter element, and 36 and 37 denote switch elements. In this CR-oscillation circuit, the capacitor elements C1 and C2 are composed of the above-mentioned capacitance type differential pressure detection element and capacitance type displacement detection element, and switches 36 and 37 are alternately opened and closed to oscillate. A voltage waveform that oscillates is obtained from the output terminal 38. This frequency has an oscillation frequency that is inversely proportional to the capacitance of each capacitor element. Therefore, by detecting this frequency in synchronization with the opening and closing of the switches 36 and 37, it is possible to detect the displacement and the differential pressure using the same detection circuit, and it is possible to realize a low-cost and compact configuration. .

[0045]

As described above, according to the fluid flow meter of the present invention, the following effects can be obtained. (1) Differential pressure detecting means for pressing the flat shield plate by the restoring force of the elastic body against the end face of the fluid introducing portion for introducing the fluid and detecting the differential pressure between the upstream side and the downstream side of the shield plate. The shield plate is displaced according to the force of the fluid, that is, according to the flow rate of the fluid, so that the flow rate is wide,
It is possible to detect the flow rate with a relatively small pressure loss, the displacement of the shielding plate, and the differential pressure between the upstream side and the downstream side. (2) Since the shield plate is supported by the gimbal spring so as to be parallel to the end face of the fluid introducing portion, the shield plate is displaced over a wide flow rate range while being parallel to the end face of the fluid introducing portion. Therefore, it is possible to detect the flow rate by the displacement and the differential pressure with high accuracy and reproducibility over a wide flow rate range. (3) Since the shield plate is made of a conductive material and the ring-shaped electrode is provided on the end face of the fluid introduction portion in parallel with the shield plate, the shield plate and the ring-shaped electrode are provided when the fluid is not flowing. The zero flow rate can be easily detected by contacting with.

Further, if the differential pressure exceeds a certain value at the zero flow rate, it can be determined that the differential pressure gauge is abnormal.

Since the zero flow rate can be detected, the differential pressure gauge can be calibrated. (4) A fluid introducing portion having a central axis for introducing the fluid, and the end face of the fluid introducing portion is pressed by the restoring force of the elastic body,
Since the flat plate-shaped shield plate that slides on the central axis, the differential pressure detection unit that detects the differential pressure between the upstream side and the downstream side of the shield plate, and the displacement detection unit, the fluid is wide. Since the flow is stable over the flow rate range, the shield plate is always displaced in parallel with the end face of the fluid introduction hole even if the flow rate changes abruptly. Therefore, the flow rate can be stably and accurately detected by the differential pressure in a wide flow rate range. (5) A fluid introduction part for introducing a fluid, a flat plate-like shield plate having a piston-like bearing pressed on the end face of the fluid introduction part by a restoring force of an elastic body, and upstream and downstream sides of the shield plate Since it is composed of a differential pressure detecting means for detecting the differential pressure between the shield plate and the displacement detecting means, even if there is a sudden change in the flow rate, the shield plate is always displaced while maintaining parallel to the end face of the fluid introduction hole. To do. Therefore, the flow rate can be accurately detected by the differential pressure and the displacement in a wide flow rate range. Further, since the slide portion can be configured not to be directly exposed to the portion where the fluid flows, it is not clogged with dust or the like and has excellent durability. (6) A fluid introducing section for introducing a fluid and a flat shield plate pressed against the end surface of the fluid introducing section by a restoring force of an elastic body. The concave-shaped differential transformer operates as an air damper even when there is a sudden flow rate change, and therefore the shielding plate does not vibrate. Therefore, even if there is a sudden change in the flow rate, the flow rate can be accurately detected by the differential pressure and the displacement. (7) The differential pressure detection means is a capacitance type differential pressure detection including a capacitor formed by bonding two alumina flat plates having an electrode in the central portion at the peripheral portions of the electrodes so that the electrodes face each other. Since it is composed of a vessel and the alumina flat plate can be easily made into a large area, it can be detected with high sensitivity. (8) The differential pressure detection means is constituted by the capacitance type differential pressure detection means, and the displacement detection means is constituted by the capacitance type displacement detection means, and the same detection circuit can be used, which is simple. Can be realized with a simple configuration.

[Brief description of drawings]

FIG. 1 is a sectional view of a fluid flow meter according to an embodiment of the present invention.

[Figure 2] Characteristic diagram of the same flowmeter

FIG. 3A is a sectional view of a fluid flow meter according to another embodiment of the present invention. FIG. 3B is a plan view of a main part of a gimbal spring of the flow meter.

FIG. 4 is a sectional view of a fluid flow meter according to another embodiment of the present invention.

FIG. 5 is a sectional view of a fluid flow meter according to another embodiment of the present invention.

FIG. 6 is a sectional view of a fluid flow meter according to another embodiment of the present invention.

FIG. 7 is a sectional view of a fluid flow meter according to another embodiment of the present invention.

FIG. 8 is a sectional view of a fluid flow meter according to another embodiment of the present invention.

FIG. 9 is a sectional view of a fluid flow meter according to another embodiment of the present invention.

FIG. 10 is a sectional view of a differential pressure gauge suitable for a fluid flow meter.

FIG. 11 is a circuit diagram of a detection circuit according to an embodiment of the present invention.

FIG. 12 is a sectional view of a conventional fluid flow meter.

[Explanation of symbols]

 9 fluid introduction hole 10 frame 11 fluid shielding plate 12 coil spring 13 differential pressure detection means 16 displacement detection means

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroshi Fujieda 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (10)

[Claims] 1. A fluid introduction part for introducing a fluid, a flat shield plate pressed against an end face of the fluid introduction part by a restoring force of an elastic body, and a differential pressure between an upstream side and a downstream side of the shield plate. A fluid flow meter provided with a differential pressure detecting means for detecting the above, and a displacement detecting means for detecting the displacement of the shielding plate. 2. The fluid flowmeter according to claim 1, wherein the shield plate is supported by a flat gimbal spring so as to move while maintaining the parallel relationship with the end face of the fluid introducing portion. 3. A fluid introduction part for introducing a fluid, a shield plate made of a flat plate-shaped conductive material pressed by a flat plate gimbal spring on an end face of the fluid introduction part, and an upstream side of the shield plate. Differential pressure detection means for detecting the differential pressure with the downstream side,
A fluid flow meter in which a ring-shaped electrode is provided in parallel with the shield plate on an end surface of the fluid introduction part, and an electrostatic capacitance is formed by the shield plate and the ring-shaped electrode. 4. A fluid introducing part for introducing a fluid, a shield plate made of a flat plate-shaped conductive material which is pressed by a flat plate gimbal spring on an end face of the fluid introducing part, and an upstream side of the shield plate. Differential pressure detection means for detecting the differential pressure with the downstream side,
A ring-shaped electrode is provided in parallel with the shield plate on the end surface of the fluid introducing portion, an electrostatic capacitance is formed by the shield plate and the ring-shaped electrode, and the shield plate is provided downstream of the shield plate. A fluid flow meter in which a concentric fixed electrode facing the central portion is provided, and a capacitance is formed between the central portion of the shielding plate and the fixed electrode. 5. A fluid introducing part having a central axis for introducing a fluid, a flat plate-like shield plate which is pressed against an end face of the fluid introducing part by a restoring force of an elastic body and slides on the central axis, and the shield. A fluid flow meter comprising: a differential pressure detecting means for detecting a differential pressure between an upstream side and a downstream side of a plate; and a displacement detecting means for detecting a displacement of the shielding plate. 6. A fluid introducing portion for introducing a fluid, a shield plate pressed against the end surface of the fluid introducing portion by a restoring force of an elastic body, and the shield plate is held by a piston-like bearing provided on the downstream side. In addition, a fluid flow meter provided with a differential pressure detecting means for detecting a differential pressure between the upstream side and the downstream side of the shielding plate, and a displacement detecting means for detecting displacement of the shielding plate. 7. A fluid introduction part for introducing a fluid, a shield plate pressed against an end face of the fluid introduction part by a restoring force of an elastic body, and a differential pressure between an upstream side and a downstream side of the shield plate is detected. A fluid flow meter in which the differential pressure detection means and the shield plate are held by a piston-shaped differential transformer provided on the downstream side. 8. A fluid introduction part for introducing a fluid, a shield plate pressed against an end surface of the fluid introduction part by a restoring force of an elastic body, and a differential pressure between an upstream side and a downstream side of the shield plate is detected. A fluid flow meter in which the differential pressure detection means and the shield plate are held by a piston-shaped differential transformer provided on the downstream side, and the differential transformer is formed in a concave shape. 9. A capacitance type differential comprising a differential pressure detecting means, which is a capacitor formed by bonding two alumina flat plates having an electrode at a central portion thereof at the peripheral portion of the electrodes so that the electrodes face each other. Claims 1, 2, 3, 4, comprising a pressure detector.
The fluid flow meter according to 5, 6, or 7. 10. A fluid introduction part for introducing a fluid, a shield plate made of a flat plate-shaped conductive material pressed by a flat plate gimbal spring on an end face of the fluid introduction part, and an upstream side of the shield plate. A differential pressure detecting means for detecting a differential pressure with the downstream side, and a ring-shaped electrode provided in parallel with the shield plate on the end surface of the fluid introducing portion, and the shield plate and the ring electrode form an electrostatic capacitance. In addition, a concentric fixed electrode facing the central portion of the shielding plate is provided in the downstream portion of the shielding plate, the central portion of the shielding plate and the fixed electrode form a capacitance, and the difference The pressure detecting means is composed of a capacitance type differential pressure detector composed of a capacitor in which two alumina flat plates having an electrode in the central portion are adhered to each other at the peripheral portions of the electrodes so that the electrodes face each other. And, using the same CR oscillation type detection circuit, A fluid flow meter that switches between each other to detect differential pressure and displacement.