JPH08159831A - Fluidic flow meter - Google Patents

Abstract

PURPOSE: To provide a fluidic flow meter capable of measuring in such a flow range with a little flow rate that a conventional fluidic flow meter not been able to measure. CONSTITUTION: The fluidic flow meter is equipped with a target 12 which is arranged downstream from a measuring nozzle 11 and divides a fluid right and left so as to generate pressure vibration in the fluid, differential pressure detection sensors 14, 15, which measure the pressures of the divided flows by the target sensor 12, and a flow rate computing means which computes flow rate from the measured pressure vibration frequency of the fluid. The fluidic flow meter is further equipped with an upper constituting portion and a lower constituting portion which constitute the upper portion and the lower portion of a measuring nozzle opening 11, two separation plates 21a, 21b which are arranged in parallel with the upper constituting portion and the lower constituting portion so as to divide the fluid flow, and a straightening net 20 which is stretched between two separation plate 21a, 21b.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluidic type flow meter for measuring the flow rate of a fluid by measuring the frequency of pressure oscillation of the flow split into left and right by a target placed in the flow of the fluid. It is a thing.

[0002]

2. Description of the Related Art Conventionally, a mechanical membrane gas meter has been widely used for measuring the flow rate of city gas. However, the membrane gas meter is large, has an old design, and is costly and problematic. Therefore, a fluidic flow meter is being developed as a gas meter to replace the membrane gas meter. Here, the operation principle of the fluidic type flow meter will be described. First, the configuration of the conventional fluidic type flow meter will be described. As shown in FIG. 9, the target 102 is arranged at the center position of the flow of the fluid F flowing from the nozzle 101. To the left and right of the target 102, the left sidewall 108 and the right sidewall 10
7 are arranged.

In the fluidic type flow meter, it is known that the fluid F alternately flows to the left and right of the target 102, as shown in FIGS. 9 and 10. The divided fluid F1,
The return guide 103 is arranged at a position where the flow of F2 collides. Then, the right differential pressure detection sensor 104 is attached at a position where the fluid F1 diverted to the right collides with the return guide 103, and the left differential pressure detection sensor 105 is provided at a position where the fluid F2 diverted to the left collides with the return guide 103. Is attached. In the fluidic flow meter, the fluid F alternately flows to the left and right, so that the differential pressure detection sensors 104 and 105 cause periodic minute pressure changes. The frequency of this minute pressure change is shown in FIG.
As shown in, it is proportional to the gas flow rate. The fluidic flow meter measures the flow rate by detecting the frequency of this minute pressure change. The optimum shape of the measurement nozzle of the fluidic flow meter has been experimentally determined as an aspect ratio, and for gas meters, for example, a measurement nozzle having a width of 3.2 mm and a height of 22 mm is used. There is.

As can be understood from the operating principle of the fluidic type flow meter described above, the pressure oscillation cannot occur unless the flow rate exceeds a certain amount, so that the flow rate cannot be measured. Therefore, in a region where the flow rate is low, the flow rate is measured by a flow sensor which is a hot wire type flow meter. On the other hand, since the gas flow meter operates on a single lithium battery for 10 years, it is necessary to reduce the current consumption as much as possible. For that purpose, the flow sensor that consumes a large amount of current is not used as much as possible and the current consumption is reduced. I want to use a small fluidic type flow meter. Therefore, it is desired to measure with a fluidic type flow meter even in a region where the flow rate is smaller.

[0005]

However, the conventional fluidic type flowmeter has the following problems. The applicants have confirmed through experiments that even if the flow rate is low, pressure fluctuations occur when the velocity of the fluid flowing through the measurement nozzle is uniform, and therefore it is possible to measure the flow rate with a fluidic type flow meter. ing. Compared to this,
The flow rate could not be measured by the fluidic type flow meter when a flow having different flow velocities collides with the target in the height direction of the target. It is considered that this is because pressure vortices do not occur because vortices are generated upstream of the target. In an actual fluidic type flow meter, since the fluid contacting the wall surface receives wall resistance in the measurement nozzle, the flow velocity is high in the central portion and slow in the vicinity of the wall face, and the flow velocity is not uniform. Therefore, there is a problem that the conventional fluidic type flow meter cannot measure in a small flow rate region where the flow rate is uniform.

The present invention has been made in order to solve the above-mentioned problems, and provides a fluidic type flow meter capable of measuring even a small flow rate region which cannot be measured by a conventional fluidic type flow meter. The purpose is to provide.

[0007]

In order to solve the above problems, a fluidic type flow meter of the present invention is arranged downstream of a measurement nozzle and splits a fluid left and right to generate pressure oscillation in the fluid. A fluidic flowmeter having a target, a piezoelectric element for measuring the pressure of the fluid divided by the target, and a flow velocity calculating means for calculating the flow velocity from the frequency of the pressure vibration of the fluid measured by the piezoelectric element, It has an upper and lower nozzle constituent part that configures the upper and lower sides of the measurement nozzle opening, a plurality of partition plates that are arranged in parallel with the upper and lower nozzle constituent parts and divide the flow of the fluid, and a rectifying network stretched between the partition plates. There is. Further, the fluidic type flow meter is characterized in that it has a second rectifying mesh which is stretched between the partition plate and the upper and lower nozzle constituent parts and has a coarser mesh than the rectifying mesh.

Further, the fluidic type flow meter of the present invention is arranged downstream of the measuring nozzle, and divides the fluid into right and left to generate a pressure oscillation in the fluid and a pressure of the fluid diverted by the fluid target. A fluidic type flowmeter having a piezoelectric element for measurement and a flow velocity calculating means for calculating a flow velocity from the frequency of pressure vibration of a fluid measured by the piezoelectric element, the upper and lower nozzle constituting parts constituting upper and lower sides of a measurement nozzle opening. And a plurality of partition plates that are arranged in parallel with the upper and lower nozzle components to divide the flow of the fluid, and in the measurement nozzle, the nozzle inlet width in the section between the upper and lower nozzle components and the partition plate is It is larger than the nozzle inlet width in the section with the partition plate.

[0009]

The measuring nozzle at the inlet of the flow rate measuring portion of the fluidic type flow meter of the present invention having the above-mentioned structure ejects the fluid toward the target. Here, a plurality of partition plates provided in the measurement nozzle divides the flow in the measurement nozzle. And the velocity of the fluid flowing into the measurement nozzle is
Due to wall resistance, it is fast in the center and slow near the wall.
Therefore, as it is, the velocity of the fluid flowing between the partition plate and the upper and lower nozzle components is slower than the velocity of the fluid flowing between the partition plates, and the flow velocity is not uniform. However, in the present invention, since the fluid flowing between the partition plates is provided with resistance by the rectifying network stretched over the plurality of partition plates, the fluid flowing between the partition plates and the flow between the partition plates and the upper and lower nozzle constituent parts are provided. The velocity of the fluid is homogenized.

The target causes the fluid ejected from the measuring nozzle to flow alternately to the left and right to generate pressure oscillation in the fluid. The piezoelectric element measures the pressure vibration generated in the fluid by measuring the pressure difference between the left and right sides of the target. The flow velocity calculating means analyzes the frequency of the pressure vibration of the fluid measured by the piezoelectric element, and calculates the flow velocity from the frequency. Even without installing a flow straightening net, by making the nozzle inlet width between the partition plate and the upper and lower nozzle components larger than the nozzle inlet width between the partition plate and the partition plate, Since more fluid can flow between the partition plate and the plate, the velocity of the fluid flowing between the partition plates and the velocity of the fluid flowing between the partition plate and the upper and lower nozzle components are made uniform.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A fluidic type flow meter which is an embodiment of the present invention will be described in detail below with reference to the drawings. FIG. 3 shows a side view of the flowmeter main body 19, and FIG. 1 shows a plan view thereof. The flowmeter main body 19 is housed in a flowmeter frame box (not shown) and functions as a flowmeter. A flow sensor inlet 38 is formed on the left side of the measurement nozzle 11 by being partitioned by the regain net 29. An IC flow sensor, which is a hot-wire type flow meter, is attached downstream of the flow sensor inlet 38. The configuration of the flow meter unit 37 will be described with reference to FIG. 2 at the entrance of measuring nozzle 11
Partition plates 21a and 21b are attached. The two partition plates 21a and 21b are arranged in parallel with the upper and lower nozzle constituent parts (not shown) which form the upper and lower sides of the opening of the measurement nozzle 11, and divide the flow of the fluid flowing into the measurement nozzle 11.

In the present embodiment, the height H3 of the opening of the measuring nozzle 11 is 38 mm, and the partition plate 21a is installed at a position lower than the height H2 of the front target 20 which will be described later. Further, the partition plate 21b is provided with the measurement nozzle 11
The pressure difference detection sensors 14 and 15 are installed from the intermediate position of the opening. A rectifying net 20 is stretched over the entire surface between the partition plates 21a and 21b. In this embodiment, the rectifying net 20 has a wire diameter of 0.18 mm, 50
Uses a mesh wire mesh.

A first target 12 is arranged on an extension of the flow path of the measuring nozzle 11. First target 12
Has a heart shape and is arranged so that the concave portion is on the upstream side. Further, a right differential pressure detection sensor 14 and a left differential pressure detection sensor 15 are attached to both sides of the opening on the side plate forming the opening of the measurement nozzle 11. The left sidewall 18 is arranged on the left side of the first target 12, and the right sidewall 17 is arranged on the right side. A second target 16 is arranged downstream of the first target 12. Further, a regain net 29 is attached to the lower surface of the measurement nozzle 11. In this embodiment, the regain net 29 has wire diameters of 0.18 mm and 50.
Uses a mesh wire mesh. The regain network 29 is for separating the flowmeter unit 37 and the flow sensor inlet 38.

In the fluidic type flow meter, the fluid F is
It is known that the first target 12 and the second target 16 flow alternately to the left and right. The return guide 13 is arranged at a position where the separated flows F1 and F2 of the fluid collide with each other. In the fluidic type flow meter, since the fluid F flows alternately to the left and right, a periodic minute pressure change is measured by taking the differential pressure between the right differential pressure detection sensor 14 and the left differential pressure detection sensor 15. It is known that the frequency of this minute pressure change is proportional to the gas flow rate. The fluidic flow meter measures the flow rate by detecting the frequency of this minute pressure change.

Next, the operation of the fluidic type flow meter having the above-described structure will be described. The fluid F flowing into the flowmeter main body 19 is flown by the regain net 29 to the flowmeter unit 37.
To the fluid flowing to the flow sensor inlet 38 and the fluid flowing to the flow sensor inlet 38. First, the fluid flowing to the flow meter unit 37 will be described. The measurement nozzle 11 is the first target 1
The fluid is jetted toward the second target 16 and the second target 16. The first target 12 and the second target 16 alternately flow the fluid ejected from the measurement nozzle 11 to the left side F2 and the right side F1. As a result, if the pressure of the fluid is observed at a fixed point, pressure oscillation of the fluid is occurring. Measuring nozzle 11
By measuring the differential pressure generated on both sides of the outlet of the measurement nozzle 11 with the right differential pressure detection sensor 14 and the left differential pressure detection sensor 15 installed on both sides of the outlet of There is. Then, the frequency of the pressure vibration of the fluid measured by the right differential pressure detection sensor 14 and the left differential pressure detection sensor 15 is measured by the control circuit, and the flow velocity is calculated from the obtained frequency.

Here, the rectifying network 20 which is the main part of the present invention.
The operation of will be described in detail. Usually, in the state where the flow straightening net 20 is not provided, there is a fluid resistance on the wall surface of the measurement nozzle 11, so that as shown in FIG. 5, the two partition plates 21a and 21b and the upper and lower nozzle constituent parts 22 are provided. The flow velocity between the two partition plates 21a and 21b is significantly slower than the flow velocity between the two partition plates 21a and 21b. In this embodiment, two partition plates 2
Since the rectifying network 20 stretched between 1a and 21b acts as a resistance against the fluid, the velocity of the fluid flowing between the two partition plates 21a and 21b is reduced, and as shown in FIG.
The flow velocity between the two partition plates 21a and 21b and the upper and lower nozzle constituting portion 22 is substantially equal to the flow velocity between the two partition plates 21a and 21b.

As a result, the flow velocity in the vertical direction of the fluid flowing through the opening of the measurement nozzle 11 can be made uniform, so that the flow rate can be measured by the fluidic type flow meter even in a region where the flow rate is smaller than in the conventional case. It was Furthermore, the two partition plates 21a and 21b and the upper and lower nozzle component 2
As shown in FIG. 7, a second flow straightening net 23 is stretched between the two partition plates 21a and 21b and the upper and lower nozzle components 22 to make the flow velocity more uniform. . In this case, the second rectifying network 23 is naturally the rectifying network 2
Use a wire mesh with a coarser mesh than 0. By disposing both the rectifying network 20 and the second rectifying network 23, the flow can be made more uniform as shown in FIG. 7, and the flow rate can be increased by the fluidic type flow meter even in a region where the flow rate is small. It becomes possible to measure.

Next, the fluid flowing to the flow sensor inlet 38 will be described. The practical measurement range of the fluidic type flow meter is 170 to 6000 liters / hour. Therefore, at a small flow rate of 3 to 170 liters / h, the flow rate is measured by the IC flow sensor 28 which is a hot wire type flow meter attached to the flow sensor inlet 38. It is the hot-wire type flowmeter that does not measure the flow rate by the IC flow sensor 28 in all the regions, so that the power consumption is large, and a gas meter that intends to supply power for 10 years with one lithium battery This is because it is necessary to switch to a fluidic type flow meter whose power consumption is as small as 1/5 of that of a hot wire flow meter. According to the present embodiment,
The practical measurement range of the fluidic type flow meter is 120 to 13
Since it can be expanded to about 0 liter / h, the amount of current used can be reduced.

As described in detail above, according to the fluidic type flow meter of this embodiment, the upper and lower nozzle constituting portions 22 constituting the upper and lower sides of the measurement nozzle opening are arranged in parallel with the upper and lower nozzle constituting portion 22. Since it has the two partition plates 21a and 21b for dividing the fluid flow and the rectifying net 20 stretched between the two partition plates 21a and 21b, the two partition plates 21a and 21b. Since the flow velocity between the upper and lower nozzle components 22 and the two partition plates 21a and 21b can be made uniform, the flow rate can be measured by the fluidic type flow meter even in a low flow rate region. Become.

Next, a second embodiment of the present invention will be described.
Since the second embodiment is similar to the first embodiment in outline,
Only different parts will be described, and description of overlapping parts will be omitted. FIG. 4A shows a sectional view taken along line AA and a sectional view taken along line CC of FIG. Since the AA cross section and the CC cross section have the same shape, they are shown in the same drawing. FIG. 4B shows a sectional view taken along the line BB of FIG. The upper and lower nozzle components 22 and the two partition plates 21a,
21b, the width of the nozzle opening is W3 and the nozzle inlet width is W1, as shown by the AA cross section and the CC cross section. Here, the nozzle width indicates a width in which a flow that hits the nozzle at a right angle flows into the nozzle opening.
Between the two partition plates 21a and 21b, the nozzle opening width is W3 and the nozzle inlet width is W2, as shown in the BB section, as in the AA section and the CC section.

In the second embodiment, W1 is made sufficiently larger than W2. As a result, the two partition plates 21a,
Two partition plates 2 due to the speed of the flow flowing between 21b
The speed of the flow flowing between the 1a and 21b and the upper and lower nozzle constituting portion 22 becomes faster. Therefore, the two partition plates 21
Flow velocity between a and 21b and two partition plates 21a and 21b
Since the flow velocity between the upper and lower nozzle components 22 can be made uniform, the flow rate can be measured by the fluidic type flow meter even in a region where the flow rate is low.

The above-described embodiments do not limit the present invention at all, and it is needless to say that various modifications and improvements can be made without departing from the scope of the invention. For example, although two partition plates are used in this embodiment, three or more partition plates may be used. In this case, the flow straightening net 20 may be stretched between the partition plates located near the upper and lower nozzle components 22. Further, the mesh of the rectifying network may be coarser toward the outside.

[0023]

As is apparent from the above description, according to the fluidic type flow meter of the present invention, the upper and lower nozzle constituent portions which form the upper and lower sides of the measurement nozzle opening are arranged in parallel with the upper and lower nozzle constituent portions. Since it has a plurality of partition plates that divide the flow of the fluid and a rectifying network that is stretched between the plurality of partition plates, the flow rate between the partition plates and the flow rate between the upper and lower nozzle components and the partition plate Therefore, the flow rate can be measured by the fluidic type flow meter even in a low flow rate region. As a result, the time for which the hot wire type flow meter is used can be reduced, and the life of the gas flow meter using the fluidic type flow meter can be extended.

[Brief description of drawings]

FIG. 1 is a plan view showing a configuration of a fluidic type flow meter which is an embodiment of the present invention.

FIG. 2 is a perspective view showing a configuration in the vicinity of a measurement nozzle of a fluidic type flow meter.

FIG. 3 is a side view of a fluidic type flow meter.

FIG. 4 is a sectional view showing the shape of a measurement nozzle 11 according to a second embodiment.

FIG. 5 is an explanatory diagram showing a configuration and a flow velocity of a measurement nozzle 11 of a conventional fluidic type flow meter.

FIG. 6 is an explanatory diagram showing the configuration and flow velocity of the measurement nozzle 11 of the fluidic type flow meter of the first embodiment.

FIG. 7 is an explanatory diagram showing a configuration and a flow velocity of a measurement nozzle 11 of a fluidic type flow meter which is a modified example of the first embodiment.

FIG. 8 is a first diagram showing the operating principle of a fluidic type flow meter.
FIG.

FIG. 9 is a second diagram showing the operating principle of the fluidic type flow meter.
FIG.

FIG. 10 is a data diagram showing the relationship between vibration frequency and gas flow rate.

[Explanation of symbols]

 11 Measuring Nozzle 12 Target 14 Right Differential Pressure Detection Sensor 15 Left Differential Pressure Detection Sensor 20 Rectifier Nets 21a, 21b Partition Plate 22 Upper and Lower Nozzle Components 23 Second Rectifier Net

 ─────────────────────────────────────────────────── ─── Continued Front Page (71) Applicant 000156813 Kansai Gas Meter Co., Ltd. 2-10-16 Higashiobashi, Higashinari-ku, Osaka-shi, Osaka (71) Applicant 000142425 Kinmon Mfg. Co., Ltd. 1-2-2 Shimura, Itabashi-ku, Tokyo No. 3 (71) Applicant 000150109 Takenaka Manufacturing Co., Ltd. 1-15-1 Nakagawanishi, Ikuno-ku, Osaka-shi, Osaka (71) Applicant 000222211 Toyo Gas Meter Co., Ltd. 2795 Motoe, Shinminato-shi, Toyama (72) Inventor Kimura Yukio 507-2 Shinhomachi, Tokai City, Aichi Prefecture, Toho Gas Co., Ltd., Research Institute of Technology (72) Inventor Takato Sato, 507-2, Shinhomachi, Tokai City, Aichi Prefecture, Toho Gas Co., Ltd. (72) Inventor Hori Fujio 2795 Motoe, Shinminato, Toyama Prefecture, Toyo Gasmeter Co., Ltd. (72) Inventor Kazumi Onui Miso, Fujisawa City, Kanagawa Prefecture No. 9-10 (72) Inventor Shigenori Okamura 4-1-2, Hirano-cho, Chuo-ku, Osaka City, Osaka Prefecture Osaka Gas Co., Ltd. (72) Inventor Shizuo Sannomiya 1-270, Sennaku, Atsuta-ku, Nagoya-shi, Aichi Prefecture Issue Aichi Clock Electric Co., Ltd. (72) Inventor Tadao Shibuya 2-10-16 Higashiobashi, Higashinari-ku, Osaka City, Osaka Prefecture (72) Inventor Toshiaki Aoki 1-2-3 Shimura, Itabashi-ku, Tokyo No. Stock Company, Kinmon Works, Central Research Institute (72) Inventor, Masanari Imasaki 4-73, Nishi-Iwata, Higashi-Osaka City, Osaka Prefecture Company, Kinmon Works, Kansai Research Center (72) Inventor, Kazuhiro Yamada, Central Chiba City, Chiba Prefecture 3-26-16 Imai Ward

Claims (3)

[Claims] 1. A target, which is arranged downstream of a measurement nozzle, divides a fluid left and right to generate pressure oscillation in the fluid, a piezoelectric element for measuring the pressure of the fluid divided by the target, and a piezoelectric element for measurement. In a fluidic type flow meter having a flow velocity calculating means for calculating a flow velocity from the frequency of pressure oscillation of the fluid, an upper and lower nozzle constituting part constituting upper and lower sides of the measurement nozzle opening, and arranged in parallel with the upper and lower nozzle constituting part. And a fluidic flow meter having a plurality of partition plates for dividing the flow of the fluid, and a rectifying network stretched between the partition plates. 2. The device according to claim 1, wherein the partition plate is stretched between the partition plate and the upper and lower nozzle constituent parts,
A fluidic type flow meter having a second rectifying network having a coarser mesh than the rectifying network. 3. A target, which is arranged downstream of the measurement nozzle, splits the fluid left and right to generate pressure oscillation in the fluid, a piezoelectric element for measuring the pressure of the fluid split by the target, and a piezoelectric element for measurement. In a fluidic type flow meter having a flow velocity calculating means for calculating a flow velocity from the frequency of pressure oscillation of the fluid, an upper and lower nozzle constituting part constituting upper and lower sides of the measurement nozzle opening, and arranged in parallel with the upper and lower nozzle constituting part. And having a plurality of partition plates that divide the flow of the fluid, in the measurement nozzle, the nozzle inlet width in the section between the upper and lower nozzle components and the partition plate, between the partition plate and the partition plate. A fluidic type flow meter characterized by being larger than the nozzle inlet width in the section.