JP2002333351A - Fluidic type flowmeter and combined type flowmeter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stabilize fluidic vibration in a small flow rate region and expand a flow rate measurement region by fluidic vibration outputs towards the small flow rate region by optimizing a position of a vibration inducing element. SOLUTION: In a fluidic type flowmeter using a fluidic element 1A which has a channel 5 obtained by connecting a nozzle 3 and a channel expansion part 4 wider than the cross section of the nozzle 3, the vibration inducing element 7 opposite to an outlet 6 of the nozzle 3 and an end block 8 arranged to the downstream side of the vibration inducing element 7, a straight line E-E' connecting leading ends of curving parts 8a and 8b of both sides of the end block 8 is made orthogonal to a center line Y-N connecting centers of the nozzle 3 and the vibration inducing element 7. A flow separation at the vibration inducing element 7 can be controlled accordingly, and therefore a two-dimensional jet when a jet from the nozzle 3 collides against the vibration inducing element 7 can be stabilized and detecting a minimum vibration can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluidic type flowmeter and a composite type flowmeter for measuring fluid flow rate and flow rate by converting fluidic vibration into an electric signal.

[0002]

2. Description of the Related Art Various proposals have been made for this type of fluidic flow meter. For example, JP-A-8-21
The example described in Japanese Patent Publication No. 0886 uses a fluidic element 100 as shown in FIG. The fluidic element 100 includes a fluid inlet 101, a nozzle 10
2. A flow path formed by sequentially connecting the flow path expanding section 103 and the fluid discharge port 104; an exciter 105 provided in the flow path expanding section 103 and facing the outlet of the nozzle 102; And an end block 106. A concave surface 10 is provided on the surface of the vibrator 105 facing the outlet of the nozzle 102.
7 are formed. Then, the top surface of the fluidic element 100 is covered by a lid (not shown) in which a pair of pressure detection ports 108 are formed on both sides of the outlet of the nozzle 102, and the pressure from the pressure detection port 108 is detected by this lid. By mounting the pressure sensor, a fluidic flow meter is formed.

[0003] In a fluidic flow meter using such a fluidic element 100, the fluid ejected from the nozzle 102 toward the downstream side is alternately distributed along the outside of the exciter 105. Most of the fluid ejected from the nozzle 102 is supplied from the channel expanding portion 103 to the fluid outlet 104.
However, a part of the fluid flows into the end block 106 and returns as a return fluid along the lower side wall of the flow path enlarged portion 103, and the fluid returns from the direction perpendicular to the jet flow of the fluid ejected from the nozzle 102. Due to the energy of the return fluid, a jet of fluid newly ejected from the nozzle 102 flows to the upper side of the exciter 105 this time, and a part thereof flows into the end block 1.
At 06, the fluid becomes return fluid along the upper side wall of the flow path expanding portion 103, and newly collides with a jet of fluid ejected from the nozzle 102 in a direction perpendicular to the direction. Due to the energy of the return fluid, a jet of fluid newly ejected from the nozzle 102 flows below the exciter 105 this time. Nozzle 10
The distribution of the jet flow ejected from 2 is repeated in this manner. Fluidic flow meters measure the flow rate of a fluid by detecting the frequency of vibration (alternating pressure waves) generated in the fluid by a pressure sensor as described above and converting the detected output to an electrical signal. is there.

[0004]

In the fluidic type flow meter, the fluid flows from the nozzle 102 having a constant width to the inducer 105.
, A high-speed flow “jet” that is faster than the flow velocity of the surrounding fluid, and an exciter 105 placed in the flow
The relationship with the "wake" seen on the downstream side of the end block is important. Considering the two-dimensional situation, the position of the exciter 105 and the end block 10
The shape of 6 plays a very important role in the fluidic vibration characteristics. To explain in more detail, there is no problem if the "jet" from the nozzle 102 is ejected into a semi-infinite space, but since the fluidic flow meter has an exciter and a wall surface, the "jet" Direction cannot be maintained. For this reason, the two-dimensional “jet” becomes unstable, and it is considered that the instability causes a start of fluidic oscillation. On the other hand, vortices (Kalman vortices) having an antisymmetric arrangement are generated on the downstream side of the vibrator 105 arranged in the flow, and the vortex street becomes a meandering flow. Therefore, it is considered that the “wake” becomes an oscillating flow and cannot be stabilized. As described above, both the “jet” and the “wake” are affected by the shape of the inducer 105 and the wall surface of the flow path enlarging portion 103 and become unstable.

As described above, the current fluidic type flow meter has poor linearity in a small flow rate range, but is suitable for measurement in a large flow rate range. 2. Description of the Related Art A composite flowmeter having a combination of a thermal flow detection sensor such as a flow sensor suitable for measuring a flow rate region and a fluidic flowmeter is used. As described above, the fluidic type flowmeter has a low minimum vibration flow rate (starting flow rate of fluidic vibration) and a wide dynamic range is desired for the flow rate range. If the fluid vibration start amount of the fluidic flow meter can be used from zero flow rate, a flow meter using only the fluidic flow meter can be realized without using a thermal flow sensor. Even if this is not the case, if the flow rate at the start of stable fluid oscillation of the fluidic flow meter can be reduced as much as possible, the required specifications for the thermal flow rate detection sensor can be relaxed.

That is, in the current composite type flow meter, for example, full scale 4000 L (liter) / h (hour)
The fluid flow meter covers a range of 200 L / h to several thousand L / h, and the thermal flow sensor covers a range of 0 to 200 L / h. For this reason, there is a drawback that it is difficult to obtain measurement accuracy in a small flow rate region since the flow rate range of the thermal type flow detection sensor is as large as two digits. As a result, strict specifications are required for the performance of the thermal type flow rate detection sensor, and when used as a flow meter, complicated signal processing and flow rate correction calculation processing are required. Therefore,
Fluidic flow meter starts fluid oscillation at 1
Even a reduction of about 100 L / h and a reduction of 80 to 90 L / h has a significant effect on improvements in ease of signal processing, reliability, and manufacturing cost.

[0007] As described above, if a design factor that can effectively control both the "jet flow" and the "wake flow" is set, a fluidic flow meter that solves the above-mentioned problems can be obtained. Therefore, by optimizing the position of the exciter, it is possible to control the flow separation at the exciter, and as a result of the experiment, it was possible to stabilize the two-dimensional jet when the "jet" from the nozzle collides with the exciter. Knew from It has also been found that it is important to stabilize the return fluid that contributes to the fluidic fluid oscillation and the fluid that goes to the fluid outlet.

It is an object of the present invention to stabilize fluidic vibration in a small flow rate region by optimizing the position of the vibrator, and to extend a flow rate measurement region by the fluidic vibration output to the small flow rate region side. .

[0009]

According to a first aspect of the present invention, there is provided a fluidic type flow meter which faces a nozzle and a flow path formed by connecting a flow path enlarged portion having a larger cross-sectional area than the nozzle and an outlet of the nozzle. A fluid flow ejected from the nozzle, comprising an exciter arranged at the position in the flow path enlargement portion, and an end block arranged in the flow path enlargement portion at a position downstream of the exciter. Fluidic element that generates an alternating pressure wave by distributing it to the left and right around the inducer, and a pressure sensor that detects an alternating pressure wave generated by the fluidic element, The end block has curved walls on both sides that curve so as to return a part of the flow of the fluid ejected from the nozzle to the nozzle side, and the curved portions on the left and right sides of the end block. Center line Y-N to the tip and a straight line E-E 'connecting, connecting the center of the the center of the nozzle 誘振Ko
Are orthogonal.

Therefore, it is possible to control the separation of the flow in the exciter, so that the two-dimensional jet when the jet from the nozzle collides with the exciter can be stabilized, and the minimum vibration detection can be improved. Become.

According to a second aspect of the present invention, there is provided a fluidic type flowmeter, wherein a flow path formed by connecting a nozzle and a flow path expansion portion having a larger cross-sectional area than the nozzle is provided at a position opposed to an outlet of the nozzle. And an end block disposed in the flow path enlarging portion at a position downstream of the exciter. The flow of the fluid ejected from the nozzle is centered on the exciter. In a fluidic flow meter comprising: a fluidic element that generates an alternating pressure wave by distributing the fluid to the left and right, and a pressure sensor that detects an alternating pressure wave generated by the fluidic element, wherein the end block is the nozzle A curved wall that is curved to return a part of the flow of the fluid ejected from the nozzle to the nozzle side, and the exciter has a straight line E- connecting the left and right ends of the curved wall. 'Or a linear E-E' even on a straight line parallel with, and is located at the intersection of the center line Y-N connecting the center of the the center of the nozzle 誘振Ko.

Therefore, it is possible to suppress the occurrence of missing pulses of fluidic vibration, and it is possible to improve the linearity of the flow rate-frequency characteristic.

According to a third aspect of the present invention, in the fluidic type flowmeter according to the first or second aspect, when the diameter of the exciter is D, the center of the exciter is the straight line E-.
The center line Y- is centered on the intersection of E 'and the center line Y-N.
They are arranged within a range of ± D / 4 in the N direction.

Therefore, it is possible to tolerate the variation in the position of the exciter in manufacturing without impairing the accuracy of the flow rate measurement.

According to a fourth aspect of the present invention, there is provided a combined flow meter.
A fluidic flow meter according to any one of to 3;
A small flow rate detection element for detecting a flow rate of the fluid in the small flow rate area;
Is provided.

Therefore, it is possible to provide a combined flow meter capable of stabilizing the direction of the jet.

According to a fifth aspect of the present invention, in the compound flow meter according to the fourth aspect, the small flow rate range detecting element is disposed on the inlet side of the nozzle of the fluidic type flow meter.

Therefore, in addition to the effect of the fourth aspect of the invention, when the flow rate of the fluid is measured by the output of the small flow rate range detecting element, the measurement can be performed without being affected by the fluctuation of the fluid flow in the nozzle. Further, it is possible to simplify the configuration of the flow path for disposing the small flow rate detection element.

According to a sixth aspect of the present invention, in the compound flow meter according to the fourth aspect, the small flow rate range detecting element is formed at a position which is not affected by a fluctuation of a fluid flow by the nozzle of the fluidic type flow meter. Is arranged in the small flow path provided.

Therefore, in addition to the effect of the fourth aspect of the present invention, when the flow rate of the fluid is measured by the output of the small flow rate range detecting element, the measurement can be performed without being affected by the fluctuation of the fluid flow in the nozzle. Become.

According to a seventh aspect of the present invention, in the first aspect of the present invention, a thermal type flow rate detection sensor is used as the small flow rate range detecting element.

Therefore, in addition to the effects of the fourth, fifth, and sixth aspects of the present invention, the measurement sensitivity in a small flow rate range can be improved.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a perspective view of a fluidic element, FIG. 2 is a plan view showing a part of the fluidic element, and FIG. 3 is a plan view showing a schematic structure of a composite flow meter.

First, the configuration of the fluidic element 1A will be described with reference to FIG. The fluidic element 1A includes a flow path narrowing section 2 having a flow path cross-sectional area narrowed in a direction of flow of a fluid indicated by an arrow, a nozzle 3, and a flow path enlarging section 4 having a larger cross-sectional area than the nozzle 3. The connected flow path 5, the vibrator 7 arranged in the flow path enlarging section 4 at a position facing the outlet 6 of the nozzle 3, and the flow path enlarging section 4 at a position downstream of the vibrator 7. End block 8 placed
And is formed of a plastic material with a symmetrical shape between a center line YN passing through the center of the nozzle 3. The upstream end of the flow path narrowing section 2 and the downstream end of the flow path expanding section 4 are open. Further, a plurality of grooves 9 are formed on the wall surfaces on both sides of the flow path restricting portion 2. 6a is an opening edge of the nozzle 3.

Such a fluidic element 1A is incorporated in the flowmeter main body 10 as shown in FIG. 3, and an opening on the upper surface is covered by a lid (not shown) for closing the upper surface of the flowmeter main body 10. . A pressure sensor (not shown) is attached to the upper surface of the lid. The pressure sensor detects an alternating pressure wave of the fluidic element 1A via a pressure detection port 11 formed on the lid on both sides on the outlet 6 side of the nozzle 3, and an electric signal corresponding to the detected pressure. Is output. In addition, a rectifying network 12 and a rectifying grid 13 are incorporated in the groove 9 formed in the fluidic element 1A.
The flow meter body 10 has a fluid inlet 14 and a fluid outlet 1
5 and a flow path 16 through which gas as a fluid flows from the fluid inlet 14 to the fluid outlet 15 is formed.
The fluidic element 1A is arranged at the center of the.
The upstream side of the flow path restricting section 2 of the fluidic element 1A is located at the fluid inlet 14 and the outlet side of the flow path expanding section 4 is located at the fluid outlet 15
It is connected to the. Further, the flow path 16 on the upstream side of the fluidic element 1A is provided with a shutoff valve 1 that shuts off the flow path 16 by the driving unit 17 when receiving an abnormal vibration such as an earthquake.
8 are assembled. The fluidic flow meter 20 is configured by the above assembly. Further, by disposing a heat-sensitive flow rate detection sensor (hereinafter, referred to as a flow sensor in the embodiment) 19 as a small flow rate detection element on the inlet side of the nozzle 3 of the fluidic element 1A,
As shown in FIG. 3, a composite type flow meter 30 is configured.
Since the flow sensor 19 outputs an electric signal according to the flow rate of the gas, the flow rate of the gas is measured based on the output.

The flow rate in the small flow rate range is obtained from the output of the flow sensor 19, which is located on the inlet side of the nozzle 3, so that the flow rate is measured independently of the fluctuation of the fluid flow in the nozzle 3. it can. Further, the configuration of the flow path for disposing the flow sensor 19 can be simplified.

The fluidic element 1 A, which is a main component of the fluidic flow meter 20, has a fluid inlet 14.
When the gas that has flowed in from the nozzle 3 blows out from the nozzle 3 toward the downstream side, the gas is alternately distributed along the outside of the vibrator 7. In FIG. 3, the state in which the gas flows above the inducer 7 will be described. Most of the gas ejected from the nozzle 3 flows from the enlarged flow path portion 4 toward the fluid outlet 15, but part of the gas flows out of the end block 8. As a result, the return fluid flows along the upper side wall of the enlarged flow path portion 4 and newly hits a jet of gas ejected from the nozzle 3 from a direction substantially perpendicular thereto. Due to the energy of the return fluid, the jet of gas newly ejected from the nozzle 3 now flows below the vibrator 7 and partially hits the end block 8 along the lower side wall of the enlarged flow path portion 4. It becomes a return fluid and hits a jet of gas newly ejected from the nozzle 3 from a direction substantially perpendicular to the jet. Due to the energy of the return fluid, a jet of gas newly ejected from the nozzle 3 flows above the exciter 7 this time. The distribution of the jet flowing from the nozzle 3 is repeated by such a Coanda effect. Fluid vibration (alternating pressure wave) generated by doing in this way is detected by a pressure sensor,
The flow rate of the gas is measured by converting the output cycle into an electric signal and recognizing it.

By the way, the end block 8 has curved walls 8a and 8b on both sides which are curved to return a part of the flow of the fluid ejected from the nozzle 3 to the nozzle 3 side. Here, in the present embodiment, a straight line EE ′ connecting the tips of the left and right curved walls 8a and 8b is orthogonal to a center line YN connecting the center of the nozzle 3 and the center of the exciter 7.

FIG. 2 shows a state where the position of the exciter 7 is fixed and the curved wall 8 is fixed.
The relationship between the exciter 7 and the end block 8 when the end block 8 is positioned on the straight line EE 'at the position where the straight lines EE' connecting the ends of a and 8b are parallel to each other is shown. This variation is a parameter for showing experimentally the relationship between the instrumental error of the No. 4 gas meter and the flow rate obtained from the fluidic frequency.

In the experiment of the flow path measurement, a combustible gas was used as a fluid, and an instrumental difference (200 L / h to 400 L) determined by a measurement method was used.
The instrumental difference of flow rate less than L / h is ± 3%, 400 L / h to 40
(The instrumental difference of 00 L / h is within ± 1.5%). FIG. 4 shows the results of the experiment. FIG. 4 shows the flow rate on the horizontal axis and the instrumental difference on the vertical axis, and uses the straight line EE ′ connecting the tips of the curved walls 8a and 8b of the end block 8 as a parameter with respect to the center of the exciter 7 in five ways. It is a graph which shows the experimental result at the time of changing.

According to the experimental results, when the relationship between the inducer 7 and the end block 8 is as shown in FIG. 2, a relatively small flow rate (500 L / h or less) and a relatively large flow rate (20 L / h or less) are used.
(00 L / h or more), it was confirmed that the instrumental error was not satisfied. On the other hand, in the case of, the instrumental difference was satisfied in the required flow rate range, and it was confirmed that the tip position of the end block 8 with respect to the position of the inducer 7 is an important factor that affects the performance of the fluidic element 1A. Was.

As another experiment, the end block 8
When the straight line EE 'connecting the tips of the left and right curved walls 8a and 8b is displaced along the center line YN passing through the center of the exciter 7, the straight line EE' The relationship between the distance and the minimum vibration flow rate was investigated. The horizontal axis in FIG. 5 is the distance of the straight line EE ′ from the center of the exciter 7, and D is the diameter of the exciter 7. The vertical axis in FIG. 5 is the minimum vibration flow rate.

According to the experimental results, the end block 8
If the straight line EE 'connecting the tips of the left and right curved walls 8a, 8b is within ± D / 4 with respect to the center of the exciter 7,
It was confirmed that the device can be used at a minimum vibration flow rate of 150 L / h or less. Desirably, the center “0” in the range of ± D / 4 is desirable. Above ± D / 4, pulse omission was observed in the fluidic oscillation cycle. If a missing pulse occurs,
For example, assuming that a 0.6-sec cycle is typical when measuring in a flow rate range of 150 L / h, it is observed that a pulse is generated in 1.2 sec which is twice the cycle if one pulse is missing, and triple if two pulses are missing. It is observed that a pulse is generated at a period of 1.8 sec of the period, and the flow rate measurement error increases. This means that the relationship between the center position of the exciter 7 and the straight line EE 'connecting the end of the end block 8 indicates that the return flow contributing to fluidic vibration and the exhaust gas not contributing do not interfere with each other. It must be arranged so that

That is, when the position of the inducer 7 is fixed and considered, if the end position of the end block 8 (straight line EE ′) is located before the inducer 7 (in the direction of the nozzle 3), the return flow Although the kinetic energy is large, the gas to be exhausted is difficult to be exhausted smoothly, so that the return flow becomes unstable and the pulse of fluidic oscillation is likely to be missing. On the other hand, the end position of the end block 8 (straight line E-
If E ′) is located after the exciter 7 (in a direction away from the nozzle 3), the gas to be exhausted is exhausted smoothly, but if it exceeds a certain value, the majority of the gas is rather exhausted. Because the fluid is exhausted and the fluid that contributes to the fluid flow as the return flow is reduced and the vibration energy is reduced, the return flow becomes unstable, and the pulse of the fluidic vibration is more likely to occur. Can be explained.

Although the mechanism is different, when the center position of the inducer 7 is more than ± D / 4 on the center line YN from the intersection of the straight line EE 'and the center line YN, the filter is in the full screen. Since pulses of the Dick oscillation frequently drop out, it is observed that the fluidic oscillation cycle is twice or three times longer, and as a result, the flow rate measurement accuracy is deteriorated. It was confirmed that this phenomenon of pulse omission hardly occurred at D / 4 or less. When D / 4 is a minimum “0”,
It was confirmed that the performance other than the instrumental error and the missing pulse, for example, the linearity S / N of the flow rate Q-fluidic frequency F was the largest.

Next, a second embodiment of the present invention will be described with reference to FIG. The same parts as those in the above embodiment are denoted by the same reference numerals, and description thereof is omitted. FIG. 6 is a plan view showing a schematic structure inside the composite flow meter. The fluidic element 1B of the present embodiment is the same as the fluidic element 1 of the embodiment.
The difference from A is that the planar outline of the fluidic element 1B is rectangular. The number of grooves 9 is increased in order to mount a plurality of rectification nets 12. Are formed by merging them. The relationship between the center position of the vibrator 7 and the tip position (straight line EE ′) of the end block 8 is the same as in the above-described embodiment.

In such a fluidic element 1B, after a plurality of rectifying networks 12 and rectifying grids 13 are assembled in the grooves 9, an opening on the upper surface is covered with a lid (not shown), and a pressure sensor is provided on the upper surface of the lid. The fluidic type flowmeter 40 is configured by attaching (not shown). Further, by disposing the flow sensor 19 in the small flow path 21, the composite flow meter 50 is configured.

In such a configuration, the small flow path 21
Is formed on the upstream side of the nozzle 3, and this small flow path 2
1 is provided with a heat-sensitive flow rate detection sensor 19,
When measuring the gas flow rate based on the output of the heat-sensitive flow rate detection sensor 19, the measurement can be performed without being affected by the fluctuation of the gas flow in the nozzle 3.

[0039]

According to a first aspect of the present invention, there is provided a fluidic type flowmeter comprising: a flow path formed by connecting a nozzle and a flow path enlarged portion having a larger cross-sectional area than the nozzle; a vibrator facing an outlet of the nozzle; In a fluidic flow meter using a fluidic element having an end block disposed downstream of the exciter, the end block is curved so as to return a part of the flow of fluid ejected from the nozzle to the nozzle side. Since the straight line EE ′ connecting the ends of the left and right curved walls of the end block and the center line YN connecting the center of the nozzle and the center of the exciter are orthogonal to each other, The flow separation at the pendulum can be controlled, whereby the two-dimensional jet when the jet from the nozzle collides with the pendulum can be stabilized, and the minimum vibration detection can be improved.

According to a second aspect of the present invention, there is provided a fluidic type flow meter, comprising: a flow path formed by connecting a nozzle and a flow path enlarged portion having a larger cross-sectional area than the nozzle; a vibrator facing an outlet of the nozzle; In a fluidic flowmeter using a fluidic element having an end block disposed downstream of the fluid, the end block is curved so as to return a part of the flow of fluid ejected from the nozzle to the nozzle side. The exciter has walls on both sides, and the exciter is on a straight line EE 'connecting the tips of the left and right curved walls or on a straight line parallel to the straight line EE', and the center of the nozzle and the center of the exciter are aligned. Since it is arranged at the intersection with the connecting center line Y-N, it is possible to suppress the occurrence of the missing pulse of the fluidic vibration, and it is possible to improve the linearity of the flow rate-frequency characteristic.

According to a third aspect of the present invention, in the fluidic type flow meter according to the first or second aspect, when the diameter of the exciter is D, the center of the exciter is a straight line EE 'and a center line Y. ± D / 4 in the direction of the center line YN around the intersection with −N
, The variation in the position of the exciter during manufacture can be allowed without impairing the accuracy of the flow rate measurement.

According to the fourth aspect of the present invention, there is provided a composite type flow meter according to the first aspect.
A fluidic flow meter according to any one of to 3;
A small flow rate detection element for detecting a flow rate of the fluid in the small flow rate area;
, It is possible to provide a composite flow meter capable of stabilizing the direction of the jet.

According to a fifth aspect of the present invention, in the compound flow meter according to the fourth aspect, the small flow rate range detecting element is disposed on the inlet side of the nozzle of the fluidic type flow meter. In addition to the effects of the present invention, when measuring the flow rate of the fluid by the output of the small flow rate detection element, the measurement can be performed without being affected by the fluctuation of the flow of the fluid in the nozzle. Can be simplified.

According to a sixth aspect of the present invention, in the composite type flow meter according to the fourth aspect, the small flow rate detecting element is formed at a position which is not affected by fluctuations of the fluid flow by the nozzle of the fluidic type flow meter. Since it is arranged in the flow path, therefore, in addition to the effect of the invention of claim 4,
When the flow rate of the fluid is measured by the output of the small flow rate range detection element, the measurement can be performed without being affected by the fluctuation of the flow of the fluid in the nozzle.

According to a seventh aspect of the present invention, the thermal flow rate detection sensor is used as the small flow rate range detecting element in the invention of any one of the fourth to sixth aspects. In addition, the measurement sensitivity in a small flow rate region can be increased.

[Brief description of the drawings]

FIG. 1 is a perspective view of a fluidic element according to a first embodiment of the present invention.

FIG. 2 is a plan view showing a part of a fluidic element.

FIG. 3 is a plan view showing a schematic structure of a combined flow meter.

FIG. 4 is a graph showing a relationship between a flow rate and an instrumental difference due to a difference in a relative position between an inducer and an end block by an experiment.

FIG. 5 is a graph showing the relationship between the distance of the end block from the center of the exciter and the minimum vibration flow rate by an experiment.

FIG. 6 is a plan view showing a schematic internal structure of the composite flow meter.

FIG. 7 is a plan view showing a schematic structure of a conventional fluidic flow meter.

[Description of Signs] 1A, 1B Fluidic element 3 Nozzle 4 Flow path enlargement section 5 Flow path 6 Nozzle outlet 7 Exciter 8 End block 8a, 8b Curved wall 19 Small flow rate area detection element, thermal flow rate detection sensor 20, 40 Fluidic type flow meter EE 'straight line YN center line

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) // G01F 3/22 G01F 1/68 101Z (72) Inventor Toshiyuki Takamiya Toshiyuki 2-chome, Naka-ku, Nagoya City, Aichi Prefecture No. 2-13 Ricoh Elemex Co., Ltd. F-term (reference) 2F030 CA04 CB01 CC13 CF01 2F035 EA04

Claims (7)

[Claims] 1. A flow path formed by connecting a nozzle and a flow path enlarged portion wider than a cross-sectional area of the nozzle, an exciter arranged in the flow path enlarged portion at a position facing an outlet of the nozzle,
An end block disposed in the flow path enlarged portion at a position on the downstream side of the exciter, and distributes the flow of fluid ejected from the nozzle to the left and right around the exciter to generate an alternating pressure wave. In a fluidic flow meter comprising: a fluidic element to be generated; and a pressure sensor to detect an alternating pressure wave generated by the fluidic element, wherein the end block is one of a flow of a fluid ejected from the nozzle. A curved wall curved on both sides to return the portion to the nozzle side, a straight line EE ′ connecting the ends of the curved walls on the left and right sides of the end block, a center of the nozzle and a center of the vibrator. And a center line YN connecting the two is orthogonal to each other. 2. A flow path formed by connecting a nozzle and a flow path enlarged portion wider than a cross-sectional area of the nozzle, an exciter disposed in the flow path enlarged portion at a position facing an outlet of the nozzle,
An end block disposed in the flow path enlarged portion at a position on the downstream side of the exciter, and distributes the flow of fluid ejected from the nozzle to the left and right around the exciter to generate an alternating pressure wave. In a fluidic flow meter comprising: a fluidic element to be generated; and a pressure sensor to detect an alternating pressure wave generated by the fluidic element, wherein the end block is one of a flow of a fluid ejected from the nozzle. A curved wall curved on both sides so as to return the portion to the nozzle side, and the vibrator has a straight line E- connecting the left and right ends of the curved wall.
E ′ or a straight line parallel to the straight line EE ′, and a center line Y− connecting the center of the nozzle and the center of the exciter.
A fluidic flow meter, which is arranged at an intersection with N. 3. When the diameter of the vibrator is D, the center of the vibrator is defined by the straight line EE ′ and the center line YN.
3. The fluidic flowmeter according to claim 1, wherein the fluidic flowmeter is disposed within a range of ± D / 4 in the direction of the center line YN with respect to an intersection with the center. 4. A fluidic flow meter according to claim 1, further comprising: a small flow rate detecting element for detecting a flow rate of a fluid in a small flow rate range;
A composite type flow meter comprising: 5. The combined flow meter according to claim 4, wherein said small flow rate detection element is disposed on an inlet side of said nozzle of said fluidic flow meter. 6. The small flow rate detecting element is arranged in a small flow rate flow path formed at a position which is not affected by a fluctuation of a fluid flow by the nozzle of the fluidic type flow meter. Item 7. A composite flow meter according to Item 4. 7. The composite flow meter according to claim 4, wherein a thermal flow rate detection sensor is used as the small flow rate range detection element.