JPH07167693A - Fluidic flowmeter - Google Patents

Abstract

PURPOSE:To provide a fluidic flowmeter in which a turbulent flow, a vortex, a pressure change, etc., are absorbed, and a measuring accuracy in a fluidic body can be improved with a flow from a gas inlet to a nozzle as a two-dimensional flow without affecting influence of dynamic pressure to the nozzle. CONSTITUTION:A fluidic flowmeter 20 comprises a fluid supply unit 21 for supplying gas, a flow rate measuring unit for measuring a flow rate of gas fed from the unit 21, a gas inlet 28 provided between the unit 21 and the measuring unit, and a gas supply unit 23 provided at an upstream side of the inlet 28. A gas storage chamber 37 is formed in the unit 23. Further, a plurality of the inlets 28 are provided, channels of the unit 21 and the inlet 28 are provided at different positions, and a sectional area of the inlet 28 is formed smaller than a sectional area of the unit 21, thereby improving a measuring accuracy of the measuring unit.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluidic flow meter for measuring the flow rate of a fluid based on the fluid vibration phenomenon of a jet flow ejected from an ejection nozzle into a flow path.

[0002]

2. Description of the Related Art As a conventional fluidic flow meter,
The one shown in FIG. 14 is known. In the figure, reference numeral 1 is a fluidic flow meter, and a shutoff valve 4 that shuts off the opening 3 and stops the gas supply when an abnormality occurs is attached to the opening 3 of the fluidic body 2 while the flow passage 4 is provided. A flow rate measuring unit 5 is provided on the downstream side of the. A gas inlet 6 is formed at the tip of the shutoff valve 4 facing the opening 3. The gas inlet 6 is a gas inlet 7 of the gas meter.
It is arranged at a right angle to. Fluidic body 2
Inside the chamber, a retention space 8 having the opening 3 as a gas inlet is provided.
The retention space 8 is communicated with the nozzle portion 9 of the flowmeter side portion 5.

The flow rate measuring section 5 is a so-called fluid vibration type flow meter, and includes a flow channel expanding section 10 provided on the downstream side of the nozzle section 9 and a target 11 arranged in the flow channel expanding section 10. And a pair of pressure or flow rate detection mechanism 12 provided in the vicinity of the inlet of the flow channel expanding section 10 as main components, and the gas outlet 1 is provided on the downstream side of the flow channel expanding section 10.
3 is formed.

In the fluidic flow meter 1, the gas flowing in from the gas inlet 7 flows into the retention space 8 via the gas inlet 6 and then flows into the flow passage expanding portion 10 via the nozzle 9. However, when jetting from the narrow nozzle portion 9 into the flow passage enlarging portion 10, it becomes a so-called return flow that is attracted to one side wall and flows backward without flowing straight due to the Coanda effect. Occurs in. The return flow imparts fluid energy in the direction orthogonal to the jet main flow in the vicinity of the opening of the nozzle portion 9 to the flow passage expanding portion 10, and serves as a control flow.
A phenomenon occurs in which the gas ejected from the nozzle portion 9 alternately flows to the left and right sides of the target 11. A change in pressure caused by the flow phenomenon of the jet flow that flows alternately to the left and right is detected by a pair of pressure or flow rate detection mechanisms, and the flow rate is measured by measuring the frequency at which the flow of this fluid switches. .

[0005]

However, in the above conventional fluidic flowmeter, the gas inlet 6 is single and the directions of the gas inlet 7 and the gas inlet 6 are at right angles. Therefore, when gas flows from the gas inlet 6 into the retention space 8 in a swirling manner, the gas flows into the retention space 10 in a three-dimensional turbulent state, which causes fluid vibration in the flow rate measurement unit 5. Becomes irregular. That is, the flow of the gas flowing from the retention space 8 into the nozzle portion 9 is required to be a two-dimensional flow having symmetry, but this is impeded and it is difficult to improve the flow rate measurement accuracy. was there.

As a solution to this, Japanese Patent Laid-Open No. 4-1
As disclosed in Japanese Patent No. 34218 and Japanese Patent Laid-Open No. 4-134219, the nozzle portion 6 of the shutoff valve 4 is covered with a wire net that protrudes into the retention space 8 through the opening portion 3, and the gas flowing out from the nozzle portion 6 is thereby covered. To rectify the above, JP-A-4-278421, and JP-A-4-4-2.
As disclosed in Japanese Patent No. 78422, a nozzle portion is projected into a retention space, a semi-cylindrical member serving as a rectifier is installed so as to cover the projection portion, and gas flowing into the retention space is introduced from both ends of the semi-cylindrical member. After flowing along the inner wall, they are merged and guided to the nozzle portion.

However, in the fluidic flowmeter using a wire net disclosed in Japanese Patent Laid-Open No. 4-134218 and Japanese Patent Laid-Open No. 4-134219, the rotary flow generated by the flow in the flow path bent at a right angle is used. While it is difficult to prevent it, there is a problem that the wire mesh is clogged or warped. Further, in the fluidic flowmeter using the semi-cylindrical rectifier disclosed in JP-A-4-278421 and JP-A-4-178422, the flow velocity of the gas flowing from the left and right sides of the semi-cylindrical shape is different. It is necessary to install the semi-cylindrical center eccentrically, but it is very difficult to determine the position, and there is a problem that the optimum position changes depending on the flow rate especially when the flow rate range is wide.

The present invention has been made in view of the above-mentioned circumstances, and absorbs turbulence, vortex, pressure fluctuations, etc., and does not affect the dynamic pressure on the nozzle portion, and from the gas inlet to the nozzle portion. It is an object of the present invention to provide a fluidic flow meter that can improve the measurement accuracy in the fluidic body by making the flow up to two-dimensional flow.

[0009]

In order to solve the above-mentioned problems, a fluidic flow meter according to a first aspect of the present invention provides a fluid supply path to which gas is supplied and a flow rate of gas supplied from this fluid supply path. This is a fluidic flow rate in which a gas inlet is provided between the flow rate measuring unit for measurement and is characterized in that a plurality of gas inlets are provided.

A fluidic flowmeter according to claim 2 is
It is characterized in that the fluid supply path and the gas introduction port are arranged such that their central axes do not exist on the same straight line.

A fluidic flowmeter according to claim 3 is
It is characterized in that two gas introduction ports are provided, and these two gas introduction ports are provided at symmetrical positions with respect to the central axis of the fluid supply passage.

A fluidic flowmeter according to claim 4 is
The cross-sectional area of the gas inlet is smaller than the cross-sectional area of the fluid supply passage.

The fluidic flowmeter according to claim 5 is
It is characterized in that a gas supply section in which an air storage chamber is formed is provided between the fluid supply path and the gas introduction port.

A fluidic flowmeter according to claim 6 is
It is characterized in that the gas supply section is a smooth flow path that allows the fluid supply path and the gas introduction port to communicate with each other without a step.

A fluidic flow meter according to claim 7 is
It is characterized in that the fluid supply passage is attached to the gas supply portion in parallel or at a right angle or in any direction.

[0016]

In the fluidic flowmeter of the present invention, since a plurality of gas inlets are provided, the gas supplied from the fluid supply path is diverted or rectified and flows into the flow rate measuring section, so that the measurement accuracy of the flow rate measuring section is improved. improves.

In the fluidic flowmeter according to the second aspect, the gas supplied from the fluid supply section does not directly collide with the nozzle inlet section, and the action of the dynamic pressure of the jet flow at the nozzle inlet section is eliminated. To improve the measurement accuracy of the flow rate measurement unit.

In the fluidic flowmeter according to the third aspect, when the gases are diverted at the symmetrical gas inlets and flow into the flow rate measuring section, they merge near the nozzle inlet section.
This results in a symmetrical two-dimensional flow.

In the fluidic flowmeter according to the fourth aspect, since the gas introduction port functions as a nozzle, the gas supplied through the fluid supply passage is narrowed down by the gas introduction port and becomes a jet flow to form a flow rate measuring unit. Flows to the side.

In the fluidic flow meter according to the fifth aspect, the pressure fluctuation of the gas generated in the fluid supply path is absorbed in the air storage chamber.

In the fluidic flow meter according to the sixth aspect, the gas smoothly flows from the fluid supply passage to the gas introduction port.

In the fluidic flow meter according to the seventh aspect, the fluid supply path is set at an arbitrary angle with respect to the gas supply section.

[0023]

Embodiments of the fluidic flowmeter of the present invention will be described below with reference to the drawings. 1 to 5
FIG. 3 is a diagram showing a fluidic flow meter according to an embodiment of the present invention. Reference numeral 20 in the figure is a reference numeral of a fluidic flow meter, and the fluidic flow meter 20 is a fluid supply path 21 to which gas is supplied, and a flow rate measuring unit for measuring the flow rate of gas supplied from this fluid supply path 21. And a multi-feeder 23 which is a gas supply unit provided between them.

The fluid supply passage 21 is a pipe having a circular cross section, and a rectifier 2 having a honeycomb structure is provided at the end of the pipe 21.
4 is attached. The fluidic body 22 is shown in FIG.
As shown in FIG. 5, the groove 27 has a rectangular shape, and the groove 27 is formed on the aluminum plate while leaving the outer frame 25 and the target 26. On the side (upstream side) of the outer frame portion 25 connected to the fluid supply path 21, two gas inlets 28 are formed on both sides as shown in FIG. 2, while the gas outlet port is on the downstream side. 29 are formed. The gas inlet 28 is formed in a rectangular cross section having a width w and a height h as shown in FIG. As shown in FIG. 3, the fluidic body 2
A stay space 31 and a nozzle portion 32 are formed in the interior of 2 by attaching a symmetrical nozzle member 30.

A nozzle mounting hole 34 and a cover mounting hole 35 are formed in the nozzle member 30, and the nozzle member 30 is fixed inside the fluidic body 22 by fitting a screw (not shown) into these mounting holes. . Nozzle member 3
On the downstream side of 0, the enlarged flow path portion 3 communicating with the nozzle portion 32.
6 is formed, the target 26 is located on the extension of the nozzle 32 in the center of the enlarged flow path 36, and the gas outlet 29 is located downstream of the target 26. The flow rate measuring unit 33 is configured by.

The multi-feeder 23 is formed in a rectangular box shape and is attached to the outer frame portion 25 on the upstream side of the fluidic main body 22, and an air storage chamber 37 is formed inside, and the air storage chamber 37 is a fluidic chamber. The structure is such that it communicates with two gas inlets 28 formed in the main body 22. A cylindrical member 38 is connected to the upstream side of the multi-feeder 23. By connecting the fluid supply passage 21 to the cylindrical member 38, gas flows from the fluid supply passage 21 through the air storage chamber 37 to the fluidic body. It is designed to be introduced inside 22.

The cylindrical member 38 has a 45 at the upstream end 38a.
The contraction taper 38b is formed at an angle of degrees, and the downstream side of the contraction taper 38b has a circular flow passage cross section.
The downstream end 38c is connected to the side plate of the air storage chamber 37. A plurality of protrusions 38d are formed on the outer periphery of the cylindrical member 38 on the side of the contraction taper 38b, so that the connection of a hose or the like is ensured. In addition, a semi-cylindrical column member 39 having an arc surface on the upstream side is attached to the fluidic main body side inside the air storage chamber 37 of the multi-feeder 23.

According to the fluidic flow meter 20 constructed as described above, the gas supplied from the fluid supply passage 21 through the rectifier 24 flows into the multi-feeder 23 through the cylindrical member 38. The gas that has flowed into the multi-feeder 23 from the cylindrical member 38 is guided to the surface (arc surface) of the semi-cylindrical member 39 and split into the left and right of the air storage chamber 37,
The gas is introduced into the retention space 31 of the fluidic body from the gas inlets 28 on both sides. In this case, since the gas inlets 28 are arranged symmetrically with respect to the central axis of the fluid supply passage 21, the dynamic pressure of the gas flow from the fluid supply passage 21 is directly influenced by the nozzle portion of the fluidic body 22. It does not act on 32 and the dynamic pressure does not affect the nozzle section 32. As a result, the dynamic pressure of the gas flow is directly increased by the nozzle portion 3.
It is possible to eliminate one of the causes of the decrease in the flow rate measurement accuracy that the proportional relationship between the flow rate and the fluid vibration frequency is not established, which occurs when acting on No. 2.

Further, the gas flowing into the retention space 31 of the fluidic body 22 flows from both sides toward the center inside the retention space 31, merges at the central portion, and then flows into the nozzle portion 32. The three-dimensional flow of the gas merged in the central portion becomes a two-dimensional flow and flows into the inside of the nozzle portion 32. That is, when the gas flowing in from two directions merges into each other and flows into the nozzle portion 32 while pressing each other, the velocity distribution becomes uniform, that is, two-dimensional in the height direction of the groove, and the flow rate measuring portion 3
3 makes it possible to perform highly accurate measurement.

Further, by making the inner diameter dp of the flow passage in the cylindrical member 38 coincide with the height h of the air storage chamber 37 of the multi-feeder, there is no step at the connecting portion between the upper and lower portions of these, and this This prevents the generation of vortices. Further, by forming the contraction taper 38b on the upstream side of the cylindrical member 38, the step with the fluid supply path 21 is eliminated, and this also prevents the generation of vortices. Furthermore, if the width W of the gas introduction port 28 is made smaller, when the gas flows into the retention space 31 through the gas introduction port 28, it becomes a symmetrical jet flow and is jetted into the retention space 31, and then two-dimensionally. Since the flow becomes a uniform flow and flows into the nozzle portion 32, the accuracy of the flow rate measuring portion can be further improved.

Next, the Qf characteristic curve of the fluidic flow meter having the above-mentioned structure will be described with reference to FIGS. 6 to 10. These figures show the relationship between the flow rate Q in the flow rate measuring unit, that is, the fluid vibration flow meter, and the vibration frequency f resulting from the switching degree of the pressure.

6 to 8, the dimension of the nozzle portion 32 is W
= 2.5 mm, L = 20 mm, H = 7.5 mm, and the Qf characteristic curve when the width w of the gas inlet port 28 is changed in three stages is shown. FIG. 9 shows Q when the gas inlet 28 is single.
10 shows a -f characteristic curve, and FIG. 10 shows a Qf characteristic curve when there are two gas inlets 28. More specifically, FIG. 6 shows that the width dimension of the gas inlet is w = 15 mm,
7 shows W = 10 mm and FIG. 8 shows W = 5 mm, showing the relationship between each flow rate Q and the vibration frequency f.

These experimental results have the most linear data when the width dimension of the gas inlet is set to w = 5 mm (FIG. 8). Especially when w = 5 mm, Q = 0.4 m ³ /
The linearity appears most in the data below h. FIG. 9 shows the case where the gas inlet is single, and the deviation of the data from the straight line occurs when Q ≦ 0.9 m ³ / h. In Figure 10, the gas inlet is 2
In two cases, deviation of the data from the straight line is recognized when Q ≦ 0.4 m ³ / h. However, the linearity is improved on the low flow rate side as compared with FIG.

Next, a second embodiment of the fluidic flowmeter of the present invention will be described with reference to FIG. This fluidic flow meter 40 shows a modified example of the multi-feeder 23 of the above-described embodiment, and the multi-feeder 23 of this embodiment is provided with the cylindrical member 38 on the lower surface side of the air storage chamber 37, The gas is introduced from the lower side of the air storage chamber 37. Therefore, the semi-cylindrical member 39 is arranged on the upper surface of the air storage chamber 37 with the arcuate surface facing the lower surface, that is, the downstream end 38c of the cylindrical member. Other configurations are similar to those of the above-described embodiment. Therefore, according to the fluidic flowmeter 40 of the second embodiment, in addition to the effects of the above-described embodiment, it is possible to deal with the gas flowing from below.

Next, a third embodiment of the fluidic flowmeter of the present invention will be described with reference to FIG. This fluidic flowmeter 50 is one in which the multi-feeder 23 of the above-described embodiment is attached to the upper surface of the fluidic body 22, a cylindrical member 38 is attached to the upper part of the air storage chamber 37, and gas is supplied from this cylindrical member 38. Is a structure that flows into the air storage chamber 37. On both sides of the upper surface of the fluidic body 22, gas inlets 28 that connect the air storage chamber 37 and the retention space 31 are arranged at positions symmetrical with respect to the central axis of the cylindrical member 38. A semi-cylindrical member 39 is attached to the lower surface with the arc surface facing the upper surface, that is, the downstream end 38c of the cylindrical member. Other configurations are similar to those of the above-described embodiment. Therefore, according to the fluidic flowmeter 50 of the third embodiment, it is possible to cope with the gas flowing from the upper side in addition to the effects of the above-described embodiment.

Next, a fourth embodiment of the fluidic flow meter of the present invention will be described with reference to FIG. This fluidic flow meter 60 is replaced with the multi-feeder 23 of the above-described embodiment, nozzles 61 communicating with the retention space 31 are attached to both side surfaces of the fluidic body 22, and a flexible hose is connected to the nozzle 61 via a connector 62. 63
Is connected. The connector 62 is rotatable 360 degrees with respect to the central axis, and the flexible hose 6
The end of 3 is bifurcated, and the end of each branch pipe is connected to the connector 62. Other configurations are the same as those in the above-described embodiment. Therefore, in the fluidic flowmeter 60 of the fourth embodiment, in addition to the effects of the above-described embodiment, the gas inflow direction is set to 3
It is possible to change 60 degrees.

[0037]

As described above, according to the fluidic flowmeter of the present invention, by providing a plurality of gas introduction ports, the gas supplied from the fluid supply path is diverted or rectified to the flow rate measuring unit. Since it flows in, it is possible to improve the measurement accuracy of the flow rate measurement unit.

According to the fluidic flowmeter of the second aspect, the fluid supply passage and the gas introduction port are arranged so that their central axes do not overlap each other, so that the fluid is supplied from the fluid supply passage. Gas can be prevented from directly flowing into the nozzle portion, and thus the action of the dynamic pressure of the jet flow can be prevented and the measurement accuracy of the flow rate measurement portion can be improved.

According to the fluidic flowmeter of the third aspect, since the two gas introduction ports are provided at symmetrical positions with respect to the fluid supply passage, the gas is diverted at the two gas introduction ports. Then, it is flowed into the flow rate measuring unit. Therefore,
It joins in the vicinity of the inlet of the nozzle portion, thereby forming a two-dimensional flow and flowing into the flow rate measuring section as a smooth flow, and the accuracy of the flow rate measuring section can be improved.

According to the fluidic flowmeter of the fourth aspect, since the cross-sectional area of the gas inlet is smaller than the cross-sectional area of the fluid supply passage, the gas inlet functions as a nozzle. Then, the gas becomes a jet flow and flows into the flow rate measurement unit side. When they join near the entrance of the nozzle part, they become a two-dimensional flow and flow into the flow rate measurement part, and the accuracy of the flow rate measurement part can be improved.

The fluidic flowmeter according to claim 5 is:
Since the gas supply unit in which the air storage chamber is formed is provided, the pressure fluctuation of the gas generated in the fluid supply path is absorbed, and the smooth gas flow to the flow rate measurement unit is promoted.

A fluidic flowmeter according to claim 6 is
Since the gas supply section is a flow path that allows continuous communication between the fluid supply path and the gas introduction port without steps, the gas flows smoothly from the fluid supply path to the flow rate measurement section, and the accuracy of the flow rate measurement section is improved. Can be improved.

The fluidic flowmeter according to claim 7 is:
The fluid supply path can be oriented in any direction with respect to the gas supply section.

[Brief description of drawings]

FIG. 1 is a perspective view of the vicinity of a gas inlet of a fluidic flow meter according to an embodiment of the present invention.

FIG. 2 is a plan view of a fluidic body according to an embodiment of the present invention.

FIG. 3 is a plan view of a fluidic body in which a flow rate measuring unit according to an embodiment of the present invention is configured.

4 is a front view of the gas introduction port of the fluidic body of the embodiment of the present invention, showing the AA cross section of FIG. 3. FIG.

FIG. 5 is a rear view of the gas supply unit of the fluidic flow meter according to the embodiment of the present invention.

FIG. 6 is a diagram showing a Qf performance curve when the width W of the gas inlet of the fluidic flow meter of the embodiment of the present invention is W = 15 mm.

FIG. 7 is a diagram showing a Qf performance curve when the width w of the gas inlet of the fluidic flow meter of the embodiment of the present invention is w = 10 mm.

FIG. 8 is a view showing a Qf performance curve when the width w of the gas inlet port of the fluidic flow meter of the embodiment of the present invention is 5 mm.

FIG. 9 is a diagram showing a Qf performance curve in the case where the fluidic flowmeter of one embodiment of the present invention has a single gas inlet.

FIG. 10 is a diagram showing a Qf performance curve in the case where the fluidic flowmeter of one embodiment of the present invention has two gas inlets.

FIG. 11 is a perspective view of the vicinity of a gas inlet of the fluidic flow meter of the second embodiment of the present invention.

FIG. 12 is a perspective view of the vicinity of a gas introduction port of a fluidic flow meter according to a third embodiment of the present invention.

FIG. 13 is a perspective view of a fluidic flow meter according to a fourth embodiment of the present invention.

FIG. 14 is a sectional front view illustrating the inside of a conventional fluidic flow meter.

[Explanation of symbols]

 20, 40, 50, 60 Fluidic flow meter 21 Fluid supply path 23 Gas supply section (multi-feeder) 28 Gas inlet 33 Flow rate measurement section 37 Air storage chamber

Claims (7)

[Claims] 1. A fluidic flowmeter having a gas introduction port provided between a fluid supply path for supplying gas and a flow rate measuring section for measuring the flow rate of gas supplied from the fluid supply path. And a plurality of the gas introduction ports are provided. 2. The fluid supply path and the gas introduction port,
The fluidic flowmeter according to claim 1, wherein the flow channels are arranged such that the central axes of the flow channels do not exist on the same straight line. 3. The gas inlet is provided at two places, and these two
The fluidic flowmeter according to claim 1 or 2, wherein the gas introduction ports at the locations are provided at positions symmetrical with respect to the central axis of the fluid supply path. 4. The fluidic flowmeter according to claim 1, wherein a cross-sectional area of the gas inlet is smaller than a cross-sectional area of the fluid supply passage. 5. The fluidic element according to claim 1, wherein a gas supply section having an air storage chamber is provided between the fluid supply path and the gas introduction port. Flowmeter. 6. The gas supply section is a smooth flow path that allows the fluid supply path and the gas introduction port to communicate with each other without steps. Fluidic flow meter. 7. The flue according to claim 1, 2, 3, 4, 5 or 6, wherein the fluid supply passage is attached in parallel or at a right angle to the gas supply portion or in any direction. Dick flow meter.