JPH05203472A - Fluidic flowmeter - Google Patents

Abstract

PURPOSE:To reduce the pressure loss of the title flowmeter to such level that the flowmeter can be used as a domestic gas meter, etc., by expanding the vibratory flow rate region of the flowmeter. CONSTITUTION:A protruding section 11 which is connected with the internal wall 6a of an expanded flow passage section 6 through a smooth curved surface 6b is formed at the front end of a jet nozzle 5 and the pressure loss of the nozzle 5 is reduced by utilizing the internal wall 6a of the section 6 as a feedback flow passage and, at the same time, the occurrence of a vortex near the jet nozzle is prevented and the vibratory flow rate region is widened. In addition, by making the vibration frequency to linearly change against an increase in flow rate, this flowmeter is made usable as a domestic gas meter, etc.

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 used for measuring the flow rate of gas or liquid.

[0002]

2. Description of the Related Art A fluidic flowmeter utilizing fluidic oscillation, which has been developed as an alternative to a conventional membrane gas meter, is small in size and has no moving parts. Research and improvement are being carried out in various fields. Further, it is desired that the conventional gas flow meter requires a rising area for mounting and is small in view of urban aesthetics and does not matter in directionality in mounting. From this point of view, there is a demand for a small and high-performance fluidic flowmeter that takes advantage of its characteristics.

As described in general textbooks, the fluidic flowmeter pays attention to the fact that the flow acts to control itself, thereby causing vibration, and that the frequency is proportional to the flow rate. It was used. Such a fluidic flowmeter is disclosed in, for example, Japanese Patent Laid-Open No. 63-31301.
No. 8 and Japanese Patent Laid-Open No. 63-139214, the basic structure and operation will be described with reference to FIG.

A set ring space 3, a flow path contracting section 4, a jet nozzle 5, and a flow path expanding section 6 are provided in this order on the path connecting the inflow tube 1 and the exhaust tube 2, and the flow path expanding section 6 is guided. The pendulum 7, side blocks 8 and end blocks 9 are provided. Here, such a fluidic flowmeter has a line-symmetrical shape with respect to a straight line connecting the jet nozzle 5 and the exciter 7. End block 9
Has walls 9a, 9b extending toward the upstream side of the flow path so as to cover the side block 8 on both sides. Also,
Behind this end block 9 is a discharge space 10.

First, the tubular flow from the upstream side of the flow path is rectified into a two-dimensional flow in the set ring space 3 and further rectified by the flow path contracting section 4 to smoothly flow toward the jet nozzle 5. Then, the jet flow rectified by the jet nozzle 5 is divided into right and left by hitting the exciter 7, but in the space of the flow path expanding portion 6 up to the end block 9, when the flow exceeds a certain flow rate, the exciter 7 is discharged. Due to the instability of the vortex behind it, a left or right biased flow is formed. Therefore, the flow that hits the end block 9
Along the front of the end block 9 and side blocks 8
Along the circumference, it reaches the outlet of the jet nozzle 5 and hits the jet stream at right angles. Therefore, the direction of the jet flow is biased in the direction opposite to the initial drift by the flow returning from the side. This causes the same thing to happen again on the opposite side, with the result that the flow leaving the jet nozzle 5 changes direction in a regular and alternating manner. The frequency of this regular directional vibration increases linearly with increasing flow rate.

However, in the case of such a fluidic flowmeter, although the frequency of vibration is almost proportional to the flow rate, the range of linear change is 150 to liter / hour.
It is 3000, which is not within the range that can be used as a household gas meter, for example. Moreover, the reduction of the pressure loss is insufficient.

For this reason, the applicant of the present invention has proposed the structure shown in FIG. The same parts as those shown in FIG. 5 are designated by the same reference numerals. First, in a general fluidic flowmeter as shown in FIG. 5, the principle of vibration is explained by the jet nozzle 5, the exciter 7,
As a result of experimentally examining basic components such as the end block 9 and the like, the flow reduction portion 4 for rectification, the jet nozzle 5
And the pendulum 7 that is the target of the flow plays a large role,
Further, it was found that the end block 9 plays a role of the return path. Therefore, basically, in order to make the most of the characteristics of the fluidic flow meter, the structure is similar to that of the general fluidic flow meter shown in FIG. 5, but in the present proposal example, the side block 8 is used. Has been omitted. Here, the end block 9 of the present proposal example is also arranged in line symmetry with respect to the straight line X connecting the center of the jet nozzle 5 and the center of the exciter 7, and the upstream side of the flow path on both sides of this end block 9 The front ends of the walls 9a and 9b facing toward are extended to a vertical line Y position with respect to the straight line X on the surface side (left side in the drawing) of the vibration exciter 7 facing the jet nozzle 5.

In such a structure, as a measurement of the oscillation phenomenon, the relationship between the flow rate and the frequency was measured.
The results shown in are obtained. In this case, the flow rate and the frequency are made dimensionless and are represented by Reynolds number and Strouhal number in FIG. As shown in FIG. 6, since the side block 8 of the conventional method is not provided,
The transition of the jet flow to the turbulent flow is delayed until the high flow rate region, and the motion of the jet flow can be directly detected, which is efficient. Further, in order to surely vibrate, it is sufficient to use the inner wall 6a of the flow passage enlarging portion 6 as a return flow passage without the side block 8. Further, since the side block 8 is not required, the internal structure becomes simpler and the pressure loss is reduced.

[0009]

As described above, the end block for returning the flow is provided in the flow path expanding portion from the exciter to the discharge pipe, and the flow path expanding portion is provided without the side block. Since the inner wall is used as a return flow path, it is possible to widen the vibration flow rate region, the vibration frequency increases almost linearly with the increase in flow rate, and there is no side block. ,
The transition of the jet flow to the turbulent flow is delayed until the high flow rate region, and the motion of the jet flow is directly detected, which is efficient. In particular, since there is no side block, the internal structure becomes simpler and the pressure loss can be reduced. Therefore, it can be used as a household gas meter or the like. However, a small vortex is generated near the jet nozzle, which causes the linearity between the frequency and the flow rate to be obstructed.

Therefore, the generation of vortices in the vicinity of the jet nozzle is suppressed, whereby the flow rate range in which the frequency and the flow rate change linearly is further expanded, and the signal due to the vibration is increased to a high S.
It is desirable that the detection can be performed with the / N ratio and that the entire device can be downsized.

[0011]

According to a first aspect of the present invention, a set ring space for rectifying a flow flowing from an inflow pipe into a two-dimensional flow, a flow-flow reducing portion for rectification, a jet nozzle, Providing a flow path expansion part on the same line in order,
A pendulum that causes a biased flow is provided at a position facing the jet nozzle in the flow path expansion portion, and extends toward the upstream side of the flow path at a position behind the exciter in the flow path expansion portion up to the discharge pipe. A return end block having walls on both sides was provided, and a protruding portion connected to the inner wall of the flow channel expanding portion with a smooth curved surface was formed at the tip of the jet nozzle.

According to the second aspect of the present invention, the smooth curved surface which is continuous with the inner wall of the flow channel expanding portion and the distal end portion of the protruding portion formed at the distal end of the jet nozzle are connected by a gentle curved surface.

According to the third aspect of the present invention, the correlation between the length L ₁ of the protruding portion of the jet nozzle and the distance L ₂ from the jet nozzle not forming the protruding portion to the exciter is L ₁ / L
₂ = 0.2 or less.

[0014]

According to the first aspect of the present invention, the end block for returning the flow is provided in the flow path expanding portion from the pendulum to the discharge pipe, and the flow path expanding portion is provided without the side block. Since the inner wall is used as a return flow path, and the projection part connected to the inner wall of the flow path expansion part with a smooth curved surface is formed at the tip of the jet nozzle, it becomes possible to widen the vibration flow rate region, and the jet nozzle Generation of vortices in the part can be suppressed, and the vibration frequency increases almost linearly as the flow rate increases. further,
Since there is no side block, the transition of the jet flow to the turbulent flow is delayed until the high flow rate region, and the movement of the jet flow is directly detected, which is efficient. In particular, since there is no side block, the internal structure becomes simpler and the pressure loss can be reduced. Therefore, it can be used as a household gas meter or the like.

According to the second aspect of the present invention, the flow is further smoothed to surely perform the vibration.

Further, according to the third aspect of the invention, it is possible to effectively suppress the turbulence of the flow formed in the space between the vortex, the jet flow, and the inner wall of the enlarged flow passage near the jet nozzle.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. First, as shown in FIG. 6, a set ring space 3, a flow path reducing section 4, a jet nozzle 5, and a flow path expanding section 6 are sequentially provided on a path connecting the inflow pipe 1 and the exhaust pipe 2, and The flow path expansion section 6 is provided with a pendulum 7 and an end block 9. Here, such a fluidic flowmeter has a line-symmetrical shape with respect to a straight line connecting the jet nozzle 5 and the exciter 7. The end block 9 has walls 9a and 9b on both sides extending toward the upstream side of the flow path. A discharge space 10 is provided behind the end block 9.

In such a structure, the tubular flow from the upstream side of the flow passage is rectified into a two-dimensional flow in the set ring space 3 and further rectified by the flow passage contracting portion 4 to smoothly flow toward the jet nozzle 5. .. Then, the jet flow rectified by the jet nozzle 5 is divided into right and left by hitting the exciter 7, but in the space of the flow path expanding portion 6 up to the end block 9, when the flow exceeds a certain flow rate, the exciter 7 is discharged. Due to the instability of the vortex behind it, a left or right biased flow is formed. Therefore, the flow that hits the end block 9 reaches the outlet of the jet nozzle 5 along the front surface of the end block 9 and further along the inner wall 6a of the flow path expanding portion 6, and hits the jet flow at a right angle. Therefore, the direction of the jet flow is biased in the direction opposite to the initial drift by the flow returning from the side. This causes the same thing to happen again on the opposite side, with the result that the flow leaving the jet nozzle 5 changes direction in a regular and alternating manner. The frequency of this regular directional vibration increases linearly with increasing flow rate. That is,
As is clear from the visualization experiment, the vortices formed on both sides of the jet flow in the flow channel expansion portion 6 in the shape of FIG. 6 act so as to alternately strike the jet flow from the side, and as a result, the jet flow also alternates. Change its direction. At this time, a small vortex that causes flow turbulence is generated in the space between the jet flow, the vortex, and the inner wall 6a of the flow path expanding portion 6 near the jet nozzle 5. Therefore, in the structure shown in FIG. 1, the jet nozzle 5 is extended in the direction of the flow passage expanding portion 6 and the tip 11a of the protruding portion 11 of the jet nozzle 5 is made perpendicular to the jet flow to form the inner wall 6a of the flow passage expanding portion 6. Since the shape is connected by the smooth curved surface 6b, the flow coming along the end block 9 and the inner wall 6a of the flow passage enlarging portion 6 is further made to collide with the jet stream along the curved surface 6b without any difficulty. It prevents turbulence in the flow and makes the vortex more stable. As a result, the vortices formed on both sides of the jet flow hit the jet flow with certainty, so that the region in which the jet flow vibrates is widened and the vibration becomes stable.

Here, as shown in FIG. 2, the tip 11a of the projecting portion 11 of the jet nozzle 5 and the above-mentioned curved surface 6b are connected by a gentle curved surface 11b to further smooth the flow. In addition, the vibration is surely performed.

As a measurement of the oscillation phenomenon, the relationship between the flow rate and the vibration frequency was measured, and the result shown in FIG. 3 was obtained. In this case, the flow rate and the frequency are made dimensionless and are represented by Reynolds number and Strouhal number in FIG. The result is that the structure shown in FIG. 6 is in the state shown in FIGS. 7 and 8.
It can be seen that the structure shown in (1) further improves the linearity.

Although a symmetrical fluidic flowmeter is used in the above-mentioned embodiment, it can be applied to an asymmetrical fluidic flowmeter.

Further, it is used as a flow meter for fuel gas, water, etc. for domestic use or industrial use, but is not particularly limited to the use.

[0023]

As described above, according to the present invention, the present invention has a set ring space for rectifying a flow flowing from an inflow pipe into a two-dimensional flow, and a flow channel for rectification. Part, a jet nozzle, and a flow channel expansion part are sequentially provided on the same line, and a pendulum for causing a biased flow is provided at a position facing the jet nozzle in the flow channel expansion part. A return end block having a wall extending toward the upstream side of the flow path is provided at a position behind the exhaust pipe at a position behind the exhaust pipe, and the inner wall of the flow path expanding portion and a smooth curved surface are provided at the tip of the jet nozzle. Since the connected protruding portion is formed, the inner wall of the flow passage expanding portion can be used as a return flow passage without having the side block, and the vibration flow rate region can be expanded. Further, it is possible to suppress the generation of vortices in the jet nozzle portion, and the vibration frequency increases almost linearly with the increase in the flow rate. Further, since there is no side block, the transition of the jet flow to the turbulent flow is delayed until the high flow rate region, and the motion of the jet flow is directly detected, which is efficient. In particular, since there is no side block, the internal structure becomes simpler and the pressure loss can be reduced. Therefore, it can be used as a household gas meter or the like.

According to the second aspect of the invention, since the smooth curved surface connected to the inner wall of the flow channel expanding portion and the tip of the protrusion formed at the tip of the jet nozzle are connected by a gentle curved surface, the flow is further improved. It can be made smoother and vibration can be reliably performed.

Further, in the invention according to claim 3, the correlation between the length L ₁ of the protruding portion of the jet nozzle and the distance L ₂ from the jet nozzle which does not form the protruding portion to the pendulum is L ₁ / L _{Since 2} = 0.2 or less, it is possible to effectively suppress the turbulence of the flow formed in the space between the vortex, the jet flow, and the enlarged inner wall of the flow passage near the jet nozzle.

[Brief description of drawings]

FIG. 1 is a horizontal sectional view showing an embodiment of the present invention.

FIG. 2 is an enlarged partial sectional view showing another embodiment of the present invention.

FIG. 3 is a characteristic diagram showing a flow rate-frequency characteristic.

FIG. 4 is a characteristic diagram in which the flow rate and the frequency are made dimensionless and are represented by Reynolds number and Strouhal number.

FIG. 5 is a horizontal sectional view showing the structure of a general fluidic flow meter.

FIG. 6 is a horizontal cross-sectional view showing the structure of a fluidic flowmeter without a side block.

FIG. 7 is a characteristic diagram showing a flow rate-frequency characteristic for comparison.

FIG. 8 is a characteristic diagram in which the flow rate and frequency are made dimensionless and are represented by Reynolds number and Strouhal number.

[Explanation of symbols]

 1 inflow pipe 2 discharge pipe 3 set ring space 4 flow path reducing part 5 jet nozzle 6 flow path expanding part 6a inner wall 6b curved surface 7 exciter 9 end block 9a wall 9b wall 11 projecting portion 11a tip portion 11b curved surface

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Toshiyuki Takamiya 6-16-10 Minamioi, Shinagawa-ku, Tokyo Inside Ricoh Seiki Co., Ltd. (72) Yuko Oshima 1-3-6 Nakamagome, Ota-ku, Tokyo Stock company Ricoh

Claims (3)

[Claims] 1. A set ring space for rectifying a flow that flows in from an inflow pipe into a two-dimensional flow, a rectifying flow passage reducing portion, a jet nozzle, and a flow passage expanding portion are sequentially provided on the same line, A pendulum that causes a biased flow is provided at a position facing the jet nozzle in the flow path expansion portion, and extends toward the upstream side of the flow path at a position behind the exciter in the flow path expansion portion up to the discharge pipe. A fluidic flowmeter characterized in that a return end block having walls on both sides is provided, and a projecting portion connected to the inner wall of the flow channel expanding portion with a smooth curved surface is formed at the tip of the jet nozzle. 2. The fluidic flow rate according to claim 1, wherein a smooth curved surface that is continuous with the inner wall of the flow channel expanding portion and a tip portion of a protruding portion formed at the tip of the jet nozzle are connected by a gentle curved surface. Total. 3. The length L ₁ of the protruding portion of the jet nozzle,
The fluidic flowmeter according to claim 1, wherein the correlation with the distance L ₂ from the jet nozzle that does not form a protrusion to the exciter is L ₁ / L ₂ = 0.2 or less.