JP2925058B2 - Fluidic flow meter - Google Patents

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 measuring a flow rate of a fluid based on a fluid oscillation phenomenon of a jet 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. Reference numeral 1 is a fluidic flowmeter, sieve to Dick body 2 of the opening 3, to block the opening 3 at the time of abnormality one shutoff valve 4 to stop the supply of gas is attached, the shut-off valve A flow rate measuring unit 5 is provided downstream of 4. A gas inlet 6 is formed at the tip of the shut-off valve 4 so as to face the opening 3, and the gas inlet 6 is arranged at right angles to the gas inlet 7 of the gas meter. Inside the fluidic body 2, the retaining space 8 to the opening 3 and the inlet of gas is formed, the residence space 8 is communicated with the nozzle part 9 of the flow meter measuring unit 5.

The flow rate measuring section 5 is a so-called fluid vibration type flow meter, and includes a flow path expanding section 10 provided downstream of the nozzle section 9 and a target 11 arranged in the flow path expanding section 10. And a pair of pressure or flow rate detection mechanisms 12 provided in the vicinity of the entrance of the enlarged flow path section 10 as main constituent elements.
3 are formed.

In the fluidic flow meter 1, the gas flowing from the gas inlet 7 flows into the retaining space 8 through the gas inlet 6, and then flows into the channel expanding portion 10 through the nozzle 9. However, when the jet flows from the narrow nozzle portion 9 into the flow channel enlarged portion 10, the so-called return flow is attracted to one side wall and flows backward without going straight due to the Coanda effect. Occurs. The return flow imparts fluid energy in a direction orthogonal to the main jet flow near the opening of the nozzle portion 9 to the flow channel expansion portion 10 and plays a role as a control flow.
A phenomenon occurs in which the gas ejected from the nozzle portion 9 flows alternately left and right on both side surfaces of the target 11. The change in pressure caused by the flow phenomenon of the jet flowing alternately 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 the fluid switches. .

[0005]

[SUMMARY OF THE INVENTION However, the above in the conventional fluidic flow meter, the gas inlet port 6 is a single, and the direction of the gas flow entering the mouth 7 and a gas inlet 6 at a right angle . Therefore, when the gas flows in a swirling shape when flowing into the stagnation space 8 from the gas inlet 6, the stagnation space is formed.
The inside of the flowmeter 8 is in a three-dimensional turbulent state, whereby the fluid vibration in the flow rate measuring unit 5 becomes irregular. That is, it is required that the flow of the gas flowing from the retaining space 8 into the nozzle portion 9 be a two-dimensional flow having symmetry, but this is hindered and it becomes difficult to improve the flow rate measurement accuracy. was there.

[0006] To solve this problem, Japanese Patent Application Laid-Open No. 4-1 is disclosed.
As shown in JP-A-34218 and JP-A-4-134219, the gas inlet 6 of the shut-off valve 4 is covered with a wire mesh projecting through the opening 3 into the retaining space 8, whereby the gas flows out of the nozzle 9 . One for performing gas rectification, Japanese Patent Application Laid-Open No. 4-278421, and Japanese Patent Application Laid-Open No. 4-2
As shown in Japanese Patent No. 78422, the nozzle portion 9 is protruded into the retaining space 8 , a semi-cylindrical member serving as a rectifier is installed so as to cover the protruding portion, and the gas flowing into the retaining space 8 is semi-cylindrical member. After flowing along the inner wall from both ends of the nozzle, they are merged and guided to the nozzle portion 9 .

However, in the fluidic flow meter using a wire mesh disclosed in Japanese Patent Application Laid-Open Nos. 4-134218 and 4-134219, the rotational flow generated by the flow of the flow path bent at a right angle is used. While it is difficult to prevent this, there has been a problem that the wire mesh is clogged or distorted. Further, in the fluidic flow meter using a semi-cylindrical rectifier disclosed in Japanese Patent Application Laid-Open Nos. 4-278421 and 4-178422, the flow rates of gas flowing from the left and right sides of the semi-cylindrical shape are different. It is necessary to displace the center of the semi-cylindrical center, but it is very difficult to determine the position, and there is a problem that the optimum position changes depending on the flow rate particularly when the flow rate range is wide.

[0008] The present invention has been made in view of the above circumstances, turbulence, vortex, without affecting the dynamic pressure in the nozzle unit while absorbing pressure fluctuations, or the gas inlet <br / It is an object of the present invention to provide a fluidic flow meter capable of improving measurement accuracy in a flow measuring unit by forming a two-dimensional flow before flowing into a nozzle.

[0009]

According to a first aspect of the present invention, there is provided a fluid flow meter comprising: a fluid supply path to which a gas is supplied; and a flow rate of the gas supplied from the fluid supply path. This is a fluidic flow meter provided with a gas introduction port between the flow rate measurement unit to be measured, and is characterized by having two gas introduction ports.

[0010] Then, a fluid supply passage and the gas inlet, such that their channel center axis does not exist on the same straight line, and wherein the placing.

Further, two gas inlets are provided for the fluid supply.
When installed at a position symmetrical with respect to the center axis of the
At the position along the center between the gas inlets
It is characterized in that a nozzle portion is provided .

[0012] The fluidic flow meter according to claim 2 is
The cross-sectional area of the gas inlet is smaller than the cross-sectional area of the fluid supply passage.

[0013] The fluidic flow meter according to claim 3 is characterized in that:
A gas supply unit having an air storage chamber is provided between the fluid supply path and the gas inlet.

The fluidic flow meter according to claim 4 is
The gas supply unit is characterized in that it is a smooth flow path that allows the fluid supply path and the gas inlet to communicate with each other without a step.

[0015] The fluidic flow meter according to claim 5 is characterized in that:
It is characterized in that the fluid supply path is attached parallel or perpendicular to the gas supply section or in any direction.

[0016]

[Action] In a fluidic flowmeter according to claim 1, since is provided two gas inlet for the gas supplied from the fluid supply passage flows are diverted or rectified to flow measuring unit, the flow measuring unit Measurement accuracy is improved.

Further, the gas supplied from the fluid supply passage is no longer collide to the inlet portion of the direct nozzle portion, the flow measuring unit by eliminating the effect of the dynamic pressure of the jet stream definitive <br/> the nozzle portion Improve the measurement accuracy.

Further , when the gas is diverted at the symmetrically arranged gas inlets and flows into the flow measuring unit, the gas inlets
At the entrance of the nozzle portion, which is a position along the central portion between the nozzles, thereby forming a symmetrical two-dimensional flow. I
Therefore, it is possible to improve the measurement accuracy in the flow measurement unit.
it can.

[0019] In a fluidic flowmeter according to claim 2, since the gas inlet to the action of the nozzle, the gas supplied through the fluid supply passage is narrowed down by the gas inlet, the flow measuring unit becomes a jet stream To the side.

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

In the fluid flow meter according to the fourth aspect , the gas flows smoothly from the fluid supply passage to the gas inlet.

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

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a fluidic flow meter according to the present invention will be described below with reference to the drawings. 1 to 5
FIG. 1 is a diagram showing a fluidic flow meter according to an embodiment of the present invention. In the figure, reference numeral 20 denotes a fluid flow meter. The fluid flow meter 20 includes a fluid supply path 21 to which gas is supplied, and a flow rate measurement unit that measures the flow rate of gas supplied from the fluid supply path 21. And a multi-feeder 23 serving as a gas supply unit provided therebetween.

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

The nozzle member 30 has a nozzle mounting hole 34 and a cover mounting hole 35 formed therein, and screws (not shown) are fitted into these mounting holes to fix the nozzle member 30 inside the fluidic body 22. . Nozzle member 3
0, the enlarged flow path 3 communicating with the nozzle 32
6, a target 26 is located at the center of the enlarged flow path 36 on an extension of the nozzle 32, and a gas outlet 29 is located downstream of the target 26. Constitute a flow rate measuring unit 33.

The multi-feeder 23 is formed in a rectangular box shape and is attached to the outer frame 25 on the upstream side of the fluidic main body 22 to form an air storage chamber 37 therein. It is structured to communicate with two gas inlets 28 formed in the main body 22. Further, a cylindrical member 38 is connected to the upstream side of the multi-feeder 23. By connecting the fluid supply path 21 to the cylindrical member 38, gas flows from the fluid supply path 21 through the air storage chamber 37 to the fluidic main body. 22 is introduced.

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

According to the fluidic flow meter 20 configured as described above, the gas supplied from the fluid supply path 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 is diverted to the left and right of the air storage chamber 37.
The gas flows into the retaining space 31 of the fluidic body from the gas inlets 28 on both sides. In this case, since the gas inlet 28 is disposed at a position symmetrical with respect to the center axis of the fluid supply passage 21, the dynamic pressure of the gas flow from the fluid supply passage 21 is directly applied to the nozzle portion of the fluidic main body 22. There is no effect on the nozzle portion 32 and no influence of the dynamic pressure on the nozzle portion 32. As a result, the dynamic pressure of the gas flow is directly
2 can be eliminated, which is one of the causes of the decrease in the flow rate measurement accuracy such that the proportional relationship between the flow rate and the fluid vibration frequency is not established.

Further, the gas flowing into the retaining space 31 of the fluidic main body 22 flows from both sides toward the center inside the retaining space 31, merges at the central portion, and then flows into the nozzle portion 32. The gas that has merged at the central portion flows into the nozzle portion 32 as a three-dimensional flow becomes a two-dimensional flow. That is, when the gases flowing in from two directions merge into each other, they flow into the nozzle part 32 while pressing each other, so that the velocity distribution becomes uniform, that is, two-dimensional in the height direction of the groove, and the flow rate measuring part 3
3 enables highly accurate measurement.

Further, by making the inner diameter dp of the flow path in the cylindrical member 38 equal to the height h of the air storage chamber 37 of the multi-feeder, there is no step at the connection between the upper and lower portions of the two. This prevents the formation of vortices. Further, by forming the contraction taper 38b on the upstream side of the cylindrical member 38, a step with the fluid supply path 21 is eliminated, thereby also preventing generation of a vortex. Furthermore, if the width W of the gas inlet 28 is reduced, when the gas flows into the staying space 31 through the gas inlet 28, the gas is jetted into the staying space 31 as a symmetrical jet flow, and then two-dimensionally. As a result, it flows into the nozzle section 32 as a typical flow, so that the accuracy of the flow rate measuring section can be further improved.

Next, the Qf characteristic curve of the fluidic flow meter having the above configuration will be described with reference to FIGS. 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 degree of pressure switching.

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

In these experimental results, the data has the most linearity when the width of the gas inlet is w = 5 mm (FIG. 8). In particular, when w = 5 mm, Q = 0.4 m ³ /
Below h, the linearity appears most in the data. FIG. 9 shows a case where there is a single gas inlet, and a data deviation from a straight line occurs when Q ≦ 0.9 m ³ / h. FIG. 10 shows that the gas inlet is 2
In this case, a deviation of the data from the straight line is observed 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 flow meter according to the present invention will be described with reference to FIG. This fluidic flow meter 40 is a modification of the multi-feeder 23 of the above-described embodiment. The multi-feeder 23 of this embodiment is provided with a cylindrical member 38 on the lower surface side of the air storage chamber 37. In this system, gas flows in 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 arc surface facing the lower surface, that is, toward the downstream end 38c of the cylindrical member. Other configurations are the same as those of the above-described embodiment. Therefore, according to the fluidic flow meter 40 of the second embodiment, in addition to the functions and effects of the above-described embodiment, it is possible to cope with gas flowing from below.

Next, a third embodiment of the fluidic flow meter according to the present invention will be described with reference to FIG. The fluidic flow meter 50 is obtained by mounting the multi-feeder 23 of the above-described embodiment on the upper surface of the fluidic main body 22. A cylindrical member 38 is mounted on an upper part of an air storage chamber 37. Flows into the air storage chamber 37. On both sides of the upper surface of the fluidic main body 22, gas introduction ports 28 for communicating the air storage chamber 37 and the retaining 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, toward the downstream end 38c of the cylindrical member. Other configurations are the same as those of the above-described embodiment. Therefore, according to the fluidic flow meter 50 of the third embodiment, in addition to the effects of the above-described embodiment, it is possible to cope with gas flowing from above.

Next, a fourth embodiment of the fluidic flow meter according to the present invention will be described with reference to FIG. This fluidic flow meter 60 is different from the multi-feeder 23 of the above-described embodiment in that nozzles 61 communicating with the stagnation space 31 are attached to both sides of the fluidic main body 22, and a flexible hose is connected to the nozzle 61 via a connector 62. 63
Are connected. The connector 62 is rotatable 360 degrees with respect to the central axis.
Reference numeral 3 denotes a bifurcated distal end, and the distal end of each branch pipe is connected to a connector 62. Other configurations are the same as those of the above-described embodiment. Therefore, the fluidic flow meter 60 of the fourth embodiment has a gas inflow direction of 3 in addition to the effects of the above-described embodiment.
It can be changed by 60 degrees.

[0037]

As described above , according to the fluidic flow meter according to the first aspect, by providing two gas inlets, the gas supplied from the fluid supply path is divided or rectified and the flow rate is reduced. Since the gas flows into the measurement unit, the measurement accuracy of the flow measurement unit can be improved.

[0038] Then, a fluid supply passage and the gas introduction port, by arranging so that the central axis of their flow paths do not overlap, the gas supplied from the fluid supply passage flows directly into the nozzle portion Therefore, the action of the dynamic pressure of the jet flow can be prevented, and the measurement accuracy of the flow rate measurement unit can be improved.

Further , since the two gas inlets are provided at positions symmetrical with respect to the fluid supply passage, the gas is equally divided at the two gas inlets and flows into the flow measuring unit. Therefore, the position along the center between the gas inlets
Converges near the inlet of the nozzle section, which is a two-dimensional flow, flows into the nozzle section as a smooth flow, and can improve the measurement accuracy of the flow rate measuring section.

According to a fluidic flowmeter according to claim 2, since the cross-sectional area of the gas inlet is a small cross-sectional area relative to the cross-sectional area of the fluid supply passage, a gas inlet port acts as a nozzle Then, the gas flows into the flow measuring unit as a jet flow. When they merge near the entrance of the nozzle, they flow into the nozzle as a two-dimensional flow,
Measurement accuracy can be improved.

The fluidic flow meter according to claim 3 is
Since the gas supply unit having the gas storage chamber is provided, pressure fluctuation of the gas generated in the fluid supply path is absorbed, and a smooth gas flow to the flow rate measurement unit is promoted. Therefore, the flow meter
The measurement accuracy of the measuring section can be improved.

The fluidic flow meter according to claim 4 is
Since the gas supply unit is a steplessly flow to continuously communicated path between the fluid supply passage and the gas inlet, the gas flows smoothly from the fluid supply passage to the flow measuring unit, measuring the flow rate measurement unit
Constant accuracy can be improved.

The fluidic flow meter according to claim 5 is
The fluid supply path can be directed in any direction with respect to the gas supply.

[Brief description of the 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 one embodiment of the present invention.

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

FIG. 4 is a front view of a gas inlet of the fluidic body according to the embodiment of the present invention, showing a cross section taken along line AA of FIG. 3;

FIG. 5 is a rear view of a gas supply unit of the fluidic flow meter according to one 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 one embodiment of the present invention is 15 mm.

FIG. 7 is a diagram showing a Qf performance curve when the width w of the gas introduction port of the fluidic flow meter according to one embodiment of the present invention is 10 mm.

FIG. 8 is a diagram showing a Qf performance curve when the width w of the gas inlet of the fluidic flow meter according to one embodiment of the present invention is w = 5 mm.

FIG. 9 is a diagram showing a Qf performance curve of the fluidic flow meter according to one embodiment of the present invention when the gas inlet is single.

FIG. 10 is a diagram showing a Qf performance curve of the fluidic flow meter according to one embodiment of the present invention when two gas inlets are provided.

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

FIG. 12 is a perspective view of the vicinity of a gas inlet 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 cross-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 unit (multi feeder) 28 Gas inlet 33 Flow rate measurement unit 37 Air storage chamber

Claims (5)

(57) [Claims] 1. A fluid flow meter having a gas inlet provided between a fluid supply path to which gas is supplied and a flow rate measuring unit for measuring a flow rate of gas supplied from the fluid supply path. And the gas inlets are provided at two places, and the gas inlets at these two places are provided.
The port is provided at a position symmetrical with respect to the central axis of the fluid supply path.
Along the center between the gas inlets
And a nozzle portion of the flow rate measuring section is provided . 2. The cross-sectional area of a gas inlet is a cross-section of a fluid supply passage.
A fluidic flow meter of claim 1, wherein that you have been a small cross-sectional area relative to product. 3. An air storage between a fluid supply passage and a gas inlet.
3. The fluidic flowmeter according to claim 1 , further comprising a gas supply unit having a chamber . 4. A gas supply unit comprising a fluid supply passage and a gas inlet.
A fluidic flow meter of claim 3, wherein a smooth flow path der Rukoto for communicating without a step between. 5. A fluid supply passage which is flat with respect to said gas supply section.
The fluidic flowmeter according to claim 3 or 4, wherein the fluidic flowmeter is mounted in a line, at a right angle, or in any direction .