JPH0682521U - Fluidic flow meter - Google Patents

Abstract

(57) [Summary] [Purpose] To reduce the fluctuation of the instrumental error characteristics with respect to the flow rate. [Configuration] Front wall 5 of nozzle 5 of fluidic oscillator
With c and the rear wall 5d as the R plane, the depth of the nozzle 5 was narrowed from the upstream side to the downstream side. [Effect] The deviation of the flow velocity distribution in the front-rear direction at the ejection port of the nozzle 5 is eliminated, and the instrumental error characteristic is improved.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an improvement of a fluidic flow meter.

[0002]

[Prior art]

 Since the vibration frequency of the fluid flowing through the fluidic oscillation element corresponds to the flow rate of the fluid, a flowmeter for measuring the vibration frequency to obtain the flow rate of gas or the like is known in Japanese Patent Laid-Open No. 4-326014.

This flow meter uses a piezoelectric film sensor to detect fluid vibration, and the measurable range of the fluidic flow meter using this piezoelectric film sensor is about 1/50 of the maximum usable flow rate. Therefore, measurement in the minute flow rate range is impossible. Therefore, in the large flow area, the fluid vibration of the fluidic oscillation element is detected by the piezoelectric film sensor, and in the minute flow area, the flow rate is detected by the flow sensor provided on the nozzle wall surface of the fluidic oscillation element.

This fluidic flow meter is configured as shown in FIGS. That is, 101 is a case, and the flow path main body 103 forming the flow path 102 is provided inside the case 101.

A nozzle 104 is provided upstream of the flow path 102, first and second targets 105 and 106 are provided downstream of the nozzle 104, and a return wall 107 is provided further downstream thereof. 108 and 109 are side walls. A so-called fluidic oscillating device is constituted by these flow paths 102 to the side wall 109.

Reference numeral 110 is a fluid outlet. The first target 105 to the side wall 109 are integrally formed with the flow path body 103 so as to project forward from the rear wall of the flow path body 103, and in front of that, as shown in FIG. A metal lid 112 is fixed via an elastic gasket 111.

A rectifying plate made of wire mesh (not shown) was provided upstream of the nozzle 104. The cross-sectional shape of the nozzle 104 at right angles to the flow direction (vertical direction in the drawing) is rectangular, and the width W of the jet outlet in the left-right direction is narrowed narrowly with respect to the length L of the nozzle 104, and the depth (depth) D Was set to be larger than the length L of the nozzle 104.

As shown in FIG. 12A, the right wall 104 a and the left wall 104 b of the nozzle 104 gradually increase in nozzle width from the upstream end (upper end in the drawing) to the downstream end (lower end in the drawing) of the nozzle 104. It was getting tougher. That is, the nozzle inlet portions of the right wall 104a and the left wall 104b were formed on the so-called R surface.

However, the front and rear wall surfaces 104c and 104d of the nozzle 104 are formed by planes parallel to each other as shown in FIG. 12B, and the depth D of the nozzle 104 is the same from the upper end to the lower end of the nozzle. It was

Therefore, the disturbance of the flow velocity distribution in the left-right direction when viewed from the front can be eliminated at the ejection port of the nozzle 104 as shown by the arrow in FIG. As described above, this is because the ratio of the length L to the width W of the nozzle 104 is sufficient, and moreover, the nozzle width is gradually increased especially at the upstream portions (the nozzle inlet portion) of the left and right wall surfaces 104b and 104a of the nozzle 104. This is because the curved surface has a narrowed shape.

[0011]

[Problems to be solved by the device]

 In the prior art, the front wall 104c and the rear wall 104d of the nozzle 104 are formed in parallel planes, and the depth of the nozzle 104 is the same from the upstream end to the downstream end (jet port) of the nozzle 104. Therefore, even if a rectifier such as a wire mesh is provided upstream of the nozzle 104, the flow velocity distribution in the front-rear direction at the nozzle ejection port is biased as shown by the arrow in FIG. There is a problem that this bias changes its state depending on the flow velocity through the meter, resulting in a large variation in the instrumental error characteristics.

Further, the gasket 111 shown in FIG. 11 may be deformed and protrude into the nozzle 104 or the flow path 102, which may be a cause of the flow of the flow velocity distribution on the surface of the nozzle front wall 104c. Furthermore, there is a problem that the instrumental error changes due to the change in the nozzle cross-sectional area due to such protrusion of the gasket 111.

FIG. 13 shows an example of the instrumental error characteristic of such a conventional fluidic flowmeter, and the instrumental error fluctuates within a range of about ± 1.3%. Then, this invention aims at providing the fluidic flowmeter which can eliminate such a problem.

[0014]

[Means for Solving the Problems]

 In order to achieve the above object, the fluidic flowmeter according to claim 1 is a curved surface in which the depth of the nozzle becomes smaller as at least one of the front wall and the rear wall of the nozzle of the fluidic oscillation element goes from upstream to downstream. It is characterized by being formed.

The invention of claim 2 is the fluidic flowmeter according to claim 1, wherein the front wall and the rear wall of the nozzle are made of a material having high rigidity. According to a third aspect of the present invention, in the fluidic flowmeter according to the first or second aspect, one of the front wall and the rear wall of the nozzle is formed into a curved surface and the other is formed into a flat surface, and the other side detects a minute flow rate. A flow sensor for

[0016]

[Action]

 Since the depth of the nozzle is narrowed by the curved surface formed on the front wall or the rear wall of the nozzle, the deviation of the flow velocity distribution in the front-rear direction at the nozzle ejection port described in FIG. 12B is reduced.

Further, since the front wall and the rear wall of the nozzle are made of a material having high rigidity, the gasket does not stick out unlike the prior art. Furthermore, it is effective to provide the flow sensor on the flat wall of the front and rear walls of the nozzle.

[0018]

【Example】

 1 (a) and 1 (b) show a first embodiment of the present invention, in which 1 is a flow path main body which constitutes a flow path 2, and an inlet 3, a chamber 4, a nozzle 5, a target 6, side walls 7a, 7b, and a return. It has a wall 8 and an exit 9. Reference numeral 10 denotes a metal lid attached to the front surface of the flow path body 1 via a gasket 11.

The cross section of the nozzle 5 perpendicular to the vertical flow is rectangular, and the wall surfaces thereof are indicated by the left and right walls 5a and 5b, and the front and rear walls 5c and 5d, respectively. As shown in FIG. 1 (a), the left and right walls 5a and 5b are formed on the R surface in the upstream portion of the nozzle 5 to narrow the width of the nozzle 5 (this is the same as the conventional one). Then, the front wall 5c and the rear wall 5d are formed on the R surface in the upstream portion of the nozzle 5, and the depth of the nozzle 5 is narrowed.

FIG. 2 shows a second embodiment of the present invention, in which a nozzle 5, a target 6, a return wall 8 and left and right walls (7a) and (7b) not shown are integrally die-cast on a lid 10. This is different from the first embodiment described above.

FIG. 3 shows a third embodiment of the present invention, in which a metal plate 12 is provided on the inside (rear side) of a lid 10, and the plate 12 has a front wall 5c of a nozzle and a front wall 12a of a fluidic oscillator. Has formed.

In the first to third embodiments, the depth of the room 4 (depth in the front-rear direction) is set to be larger than the depth D of the downstream end ejection port of the nozzle 4. In the above-described first to third embodiments, since the upstream portions of the front wall 5c and the rear wall 5d of the nozzle 5 are defined as the R planes, the depth of the nozzle 5 in the front-rear direction is narrowed. Therefore, as shown in FIG. The flow velocity distribution (arrow A) in the front-back direction in Fig. 4 is biased because the flow is narrowed by the front and rear walls 5c and 5d, and the flow velocity distribution becomes uniform at the nozzle outlet as shown by arrow B. .

As described above, the effect of eliminating the bias of the flow velocity distribution in the front-back (depth) direction due to the throttling action of the front and rear walls 5c and 5d may be achieved by only one of the front and rear walls being the R surface. An example thereof is shown in FIGS.

In the fourth embodiment shown in FIGS. 5 to 8, only the front wall 5c of the nozzle 5 is formed in the R surface at the upstream portion thereof to reduce the depth of the nozzle 5. The rear wall 5d of the nozzle 5 is a flat surface as in the conventional case, and the thermal flow sensor 13 for detecting the flow rate at a minute flow rate is arranged on the rear wall. Incidentally, 14 is a second target, and 15 and 16 are first and second straightening vanes, which are made of wire mesh. The plate 12 is installed in contact with the front ends of the targets 6 and 14, the side walls 7a and 7b, the return wall 8 and the like so as to cover the front surface of the flow path 2 of the fluidic oscillation element and the nozzle 5.

In the fourth embodiment of FIG. 5 to FIG. 8, the effect that the depth of the nozzle is narrowed by the R surface of the front wall 5 c of the nozzle 5 and the front wall of the nozzle is not the gasket but the metal plate 12 is used. Because of the fact that the flowmeter is formed of, and so-called no protrusion, the fluctuation of the instrumental error as a flowmeter is reduced and it is improved as shown in Fig. 9.

This instrumental error characteristic is suppressed to a fluctuation range of about 38% as compared with the instrumental error characteristic of the prior art shown in FIG. 13, and the state of improvement is clear.

[0027]

[Effect of device]

 Since the fluidic flow meter of the present invention is configured as described above, the nozzle (5) reduces the depth in the front-rear direction, and the fluctuation of the instrumental characteristic with respect to the flow rate becomes small.

Further, since the gasket does not protrude to the nozzle (5) or the flow path (2), the flow velocity distribution is not disturbed by the protrusion of the gasket. The result also improves the instrumental error characteristics.

Furthermore, since one of the front and rear walls of the nozzle (5) is a curved surface and the other is a flat surface, and a flow sensor for detecting the flow velocity is arranged on the side of this flat surface, a diaphragm with a curved surface is formed. There is no loss in the effect of.

[Brief description of drawings]

FIG. 1 is a first embodiment of the present invention, FIG. 1A is a front view with a lid removed, and FIG. 1B is a sectional view taken along line AA of FIG. 1A.

FIG. 2 is a vertical sectional side view of a second embodiment of the present invention.

FIG. 3 is a vertical sectional side view of a third embodiment of the present invention.

FIG. 4 is a view for explaining the operation of the embodiment of the present invention.

FIG. 5 is a front view of the essential parts of a fourth embodiment of the present invention.

6 is a sectional view taken along line BB of FIG.

7 is a cross-sectional view taken along the line CC of FIG.

FIG. 8 is a front view of the plate 12 shown in FIG.

FIG. 9 is a diagram of flow rate vs. instrument difference line.

FIG. 10 is a front view in which a part of a conventional technique is longitudinally cut.

FIG. 11 is a vertical side view of a conventional technique.

FIG. 12 is a diagram for explaining the flow velocity distribution at the nozzle ejection port,
(A) shows the distribution in the left-right direction, and (b) shows the distribution in the front-back direction.

FIG. 13 is a flow chart of flow rate versus instrument difference.

[Explanation of symbols]

 5 Nozzle 5c Front wall 5d Rear wall D ... Depth 13 ... Flow sensor

Continued Front Page (72) Creator Hirokazu Kanda 1-270, Sennen-ku, Atsuta-ku, Nagoya, Aichi Prefecture Aichi Clock Electric Co., Ltd. Kansai Gas Meter Co., Ltd.

Claims (3)

[Scope of utility model registration request] 1. A fluidic flowmeter, wherein at least one of a front wall and a rear wall of the nozzle of the fluidic oscillator is formed by a curved surface whose nozzle depth decreases from upstream to downstream. 2. The fluidic flowmeter according to claim 1, wherein the front wall and the rear wall of the nozzle are made of a material having high rigidity. 3. The fluidic according to claim 1, wherein one of the front wall and the rear wall of the nozzle is formed into a curved surface and the other is formed into a flat surface, and the other side is provided with a flow sensor for detecting a minute flow rate. Flowmeter.