JPH10213462A - Fluid vibration type flowmeter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the flow of a fluid from being disturbed due to a sensor by providing an enlarged channel part halfway through a nozzle channel and a low flow-rate sensor at the enlarged channel part. SOLUTION: An enlarged channel part 211 is provided halfway through a nozzle channel 210, and a low flow-rate sensor 212 is provided at the enlarged channel part 211. The nozzle channel 210 comprises one nozzle surface and a nozzle surface that opposes in parallel with it, and the enlarged channel part 211 is formed by two recessed parts where the section that is symmetrical left and right being formed on both nozzle surfaces is in arc shape. The low flow-rate sensor 212 is a cylindrical thermal flow sensor and is provided coaxially to the enlarged channel part 211 on a nozzle center surface C, thus detecting a fluid vibration through a pressure take-out port 4 in the case of a high flow rate and measuring a flow rate and measuring a flow rate by the low flow-rate sensor 212 in the case of a low flow rate. In this manner, since the low flow-rate sensor 212 is provided at the enlarged channel part 211, the nozzle channel 210 cannot become narrow and the disturbance of a gas flow due to the low flow-rate sensor 212 can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluid vibration type flow meter for detecting a flow rate based on a fluid vibration of a fluid ejected from a nozzle flow path, and a low flow rate sensor capable of measuring a lower flow rate. The present invention relates to a fluid vibration type flow meter provided.

[0002]

2. Description of the Related Art Japanese Patent Application Laid-Open Nos. 4-134218 and 6-341 are examples of this type of fluid vibration type flowmeter.
No. 869 and Japanese Patent Application Laid-Open No. 8-14981 are known. The fluid vibration type flow meters described in these publications have a configuration in which a low flow rate sensor is provided in a nozzle flow path as it is.

[0003]

However, in the above-mentioned conventional fluid vibration type flow meter, since the low flow rate sensor is provided in the nozzle flow path as it is, the flow of the fluid is disturbed by the low flow rate sensor. is there. In addition, since the nozzle flow path is narrowed by the low flow rate sensor, there is a problem that only a low flow rate sensor extremely small with respect to the width of the nozzle flow path can be used.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem, and an object of the present invention is to provide a low flow rate sensor having various sizes in a nozzle flow path, and a flow rate of a fluid by the low flow rate sensor. An object of the present invention is to provide a fluid vibration type flowmeter capable of preventing disturbance.

[0005]

According to a first aspect of the present invention, there is provided a fluid detecting apparatus for detecting a flow rate based on a fluid vibration of a fluid ejected from a nozzle flow path having a predetermined width. A vibratory flow meter, wherein an enlarged flow path is provided in the middle of the nozzle flow path, and a low flow rate sensor is provided in the expanded flow path.

According to a second aspect of the present invention, in the first aspect, the nozzle flow path is constituted by one nozzle surface and the other nozzle surface facing the nozzle surface.
The enlarged flow path portion is formed by a concave portion formed on each of the one and other nozzle surfaces, and each concave portion is formed symmetrically with respect to a nozzle center plane passing through the center of the nozzle flow path, and has an arc-shaped cross section. And the low flow rate sensor is provided coaxially in the enlarged flow path portion.

The invention according to claim 3 is characterized in that, in the invention according to claim 2, each concave portion is formed by a side surface of the same cylinder having a center on the nozzle center plane at a symmetrical left-right position.

According to a fourth aspect of the present invention, in the first aspect of the invention, the nozzle flow path includes one nozzle surface and the other nozzle surface facing the nozzle surface,
The enlarged flow path portion is constituted by a concave portion formed on each of the one and other nozzle surfaces, and each concave portion is formed symmetrically with respect to a nozzle center plane passing through the center of the nozzle flow path, and has a rectangular cross section. And the low flow rate sensor is provided coaxially in the enlarged flow path portion.

According to a fifth aspect of the present invention, in the first, second, third or fourth aspect of the present invention, the low flow rate sensor is formed in a cylindrical shape.

[0010] The first aspect of the present invention is configured as described above.
In the invention according to the present invention, since the enlarged flow path portion is provided in the nozzle flow path, and the low flow rate sensor is provided in this expanded flow path portion,
It is possible to prevent the low flow rate sensor from narrowing the nozzle flow path. Therefore, low flow sensors of various sizes can be used regardless of the width of the nozzle flow path. Therefore, for example, even if the width of the nozzle flow path is different,
A low flow sensor having the same dimensions can be used, and there is no need to newly develop a low flow sensor according to the width of the nozzle flow path.

Further, since it is possible to prevent the low flow rate sensor from narrowing the nozzle flow path, it is possible to prevent the flow of the fluid from being disturbed by the low flow rate sensor as compared with a case where the low flow rate sensor is directly provided in the nozzle flow path. Can be prevented. That is, in the measurement of the flow rate based on the fluid vibration,
A decrease in measurement accuracy can be prevented. Also,
Also in the measurement by the low flow rate sensor, it is possible to prevent the measurement accuracy from lowering.

In the invention according to the second aspect, the enlarged flow path portion is formed by the concave portions formed symmetrically with respect to the center plane of the nozzle and formed in an arc-shaped cross section, and coaxial with the enlarged flow passage portion. Since the low flow rate sensor is provided in the shape, a symmetric vortex is generated in the flow path along each concave portion. Then, the vortex circulates in each concave portion to rectify the flow in the nozzle flow path.
Disturbance of the flow in the nozzle flow path can be reliably prevented.

According to the third aspect of the present invention, since each concave portion is formed by the side surface of the same cylinder having the center on the nozzle center surface at the symmetrical left-right position, the concave portion is formed by a drill or the like.
Each recess can be formed simultaneously and simply.

[0014] In the invention according to claim 4, also in claim 2
As in the invention according to the first aspect, it is possible to reliably prevent the flow from being disturbed by the low flow rate sensor.

According to the fifth aspect of the present invention, since the low flow rate sensor is formed in a columnar shape, a vortex that becomes more symmetrical left and right is generated in the flow path along each concave portion.
Therefore, it is possible to more reliably prevent the flow from being disturbed by the low flow rate sensor.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to FIGS. 1 to 4 show the first embodiment, FIG. 5 shows the second embodiment, and FIG.
13 shows another example of the embodiment.

First, in the first embodiment of the present invention, L
A fluid vibration type flow meter used as a P gas meter will be described with reference to FIGS.

In the fluid vibration type flow meter shown in this embodiment, a pair of flow path forming members 2 and 2 are provided in a housing 1 so that a nozzle flow path 210 having a predetermined width is formed in the housing 1. The nozzle flow path 21
The upstream flow path 200 and the downstream flow path 220 are respectively formed on the upstream side and the downstream side of 0.

The downstream flow path 220 has a nozzle flow path 210
The target 3 is provided on a nozzle center plane C that bisects the nozzle flow path 210 through the center of the nozzle flow path 210. The gas (fluid) ejected through the nozzle flow path 210 collides with the target 3 to generate fluid vibration, and the principle is to detect the flow rate based on the fluid vibration.

The housing 1 is formed by a box-shaped rectangular groove 1a formed in a concave shape. Then, by covering the surface of the groove 1a with a cover (not shown),
Upstream channel 200, nozzle channel 210, and downstream channel 2
20 are formed.
That is, the height of the upstream flow path 200, the nozzle flow path 210, and the downstream flow path 220 from the reference surface 10, which is the bottom surface of the groove 1a (the dimension in the direction orthogonal to the paper surface of FIG. 1), is constant.
It is a two-dimensional flow path formed symmetrically via the nozzle center plane C.

The housing 1 has a downstream flow path 22.
Two pressure outlets 4 are provided near the nozzle flow path 210 at 0. A pressure sensor is connected to these pressure outlets 4, and the pressure sensor detects the fluid vibration of the jet jetting from the nozzle flow channel 210.

Further, the housing 1 has a screw hole 1e for fixing a cover (not shown) and a screw hole (not shown) for fixing the flow path forming member 2. . Each of the flow path forming members 2 is formed with a through hole 2a through which a bolt (not shown) for fixing the cover passes, and also for fixing the flow path forming members 2 and 2 themselves to the housing 1. Through holes 2b through which the bolts 7 pass.

On the side of the inlet 1b of the housing 1,
A gas supply path 5 for rectification is attached, and another flow path (not shown) is attached to the outlet 1c side of the housing 1.

The gas supply path 5 includes a cylindrical portion 51 and a flat rectangular portion 52 connected to the cylindrical portion 51 and for attaching the cylindrical portion 51 to the housing 1. The cylindrical portion 51 is provided with a rectifying honeycomb 53 and a flow reducing member 54 for gradually adjusting the inner surface of the cylindrical portion 51 to the flat rectangular portion 52. In the flat rectangular portion 52, an enlarged flow member 55 for gradually expanding the flow path with respect to the cylindrical portion 51 and a symmetrically formed center plane of the gas supply path 5 that coincides with the nozzle center plane C are formed. And a semi-cylindrical column 56 are provided.

On the other hand, the nozzle flow path 210 is provided with an enlarged flow path section 211 in the middle thereof, and the expanded flow path section 211 is provided with a low flow rate sensor 212.

As shown in FIG. 2, the nozzle flow path 210
It is constituted by one nozzle surface 210a and the other nozzle surface 210b opposed in parallel to the nozzle surface 210a. In addition, these nozzle surfaces 210a, 210b
Are formed on the left and right flow path forming members 2.

The enlarged flow passage 211 is provided with concave portions 211a, 2b formed in one and the other nozzle surfaces 210a, 210b.
11b. Each of these recesses 211
a and 211b are formed symmetrically with respect to the nozzle center plane C passing through the center of the nozzle flow path 210, and have a circular cross section. Then, each recess 211a,
The center of the arc of 211b is located on the nozzle center plane C. In other words, each of the recesses 211a and 211b is formed by a side surface of the same cylinder having a center on the nozzle center plane C at symmetrical left and right positions.

The low flow rate sensor 212 is a heat flow sensor formed in a column shape. And this low flow sensor 2
12 is on the nozzle center plane C,
Are provided coaxially.

In the fluid vibration type flow meter constructed as described above, as shown in FIG. 1, after the gas flowing into the gas supply path 5 is divided into two directions by the semicircular column 56, the flow path forming member is formed. 2 collides with the upper end of the
And flows into the nozzle flow path 210 so as to collide at the entrance of the nozzle. Then, from the nozzle flow path 210 to the downstream flow path 2
Since the frequency of the fluid vibration of the gas ejected to the nozzle 20 and the flow rate or flow rate of the gas are in a proportional relationship, the flow rate can be measured. Separately, a low flow sensor 2
12 allows even lower flow rates to be measured. That is, when the flow rate is high, the flow rate can be measured by detecting the fluid vibration through the pressure outlet 4, and when the flow rate is low, the flow rate can be measured using the low flow rate sensor 212. .

Further, since the low flow rate sensor 212 is provided in the enlarged flow path section 211 located in the middle of the nozzle flow path 210, it is possible to prevent the low flow rate sensor 212 from narrowing the nozzle flow path 210. . Accordingly, the low flow rate sensors 21 of various sizes regardless of the width of the nozzle flow path 210
2 can be used. Therefore, for example, even if the nozzle flow paths 210 have different widths, the low flow rate sensors 212 having the same dimensions can be used, and the nozzle flow paths 210
It is not necessary to newly develop the low flow rate sensor 212 according to the width of.

Further, since it is possible to prevent the low flow rate sensor 212 from narrowing the nozzle flow path 210, the gas flow becomes lower than when the low flow rate sensor 212 is provided in the nozzle flow path 210 as it is. 212 can be prevented from being disturbed. That is, in measuring the flow rate based on the fluid vibration, it is possible to prevent the measurement accuracy from decreasing. Also, in the measurement by the low flow rate sensor 212, it is possible to prevent the measurement accuracy from lowering.

Each recess 211 is formed symmetrically with respect to the center plane C of the nozzle and has an arc-shaped cross section.
Since the low flow rate sensor 212 is provided coaxially with the enlarged flow path portion 211, the symmetrical vortex V is formed in the flow path along each of the concave portions 211a and 211b. Will happen. And this vortex V
Is circulated in each of the concave portions 211a and 211b,
Since the flow in the nozzle flow path (210) is rectified, it is possible to reliably prevent the flow from being disturbed by the low flow rate sensor 212. In addition, since the low flow rate sensor 212 is formed in a columnar shape, a vortex V that is more precisely symmetrical is generated in the flow path along each of the concave portions 211a and 211b. Therefore, it is possible to more reliably prevent the flow from being disturbed by the low flow rate sensor.

Further, since each of the recesses 211a and 211b is formed by the side surface of the same cylinder having the center on the nozzle center plane C at the left-right symmetric position, these recesses 211a and 211b are formed.
The 211b can be formed simultaneously and easily by a drill or the like.

Next, a description will be given of an experimental example performed by the above embodiment. FIGS. 3 and 4 use the nozzle channel 210 having a width of 2.5 mm, the concave portions 211a and 211b having an arc diameter of 3.85 to 3.95 mm, and the low flow rate sensor 212 having a diameter of 7.62 mm. Shows the results of an experiment using air as the gas. In these figures, the horizontal axis shows the number of difference pulses detected by the heat flow sensor, and the vertical axis shows the flow rate of air [l / h].
In these figures, the same experimental results are plotted. FIG. 3 shows a curve obtained by approximating the data of the experimental results by a cubic equation, and FIG. Shows a curve approximated by.

From FIGS. 3 and 4, it can be seen that the data of the experimental results plotted are substantially distributed on the curves. Therefore, it is understood that the flow in the nozzle flow path 210 is not disturbed despite the provision of the low flow rate sensor 212. The curve approximated by the cubic or quaternary expression was very close to the experimental result. Therefore, the flow rate can be accurately obtained from the number of pulses by using these cubic or quartic expressions.

Next, a second embodiment of the present invention will be described with reference to FIG. However, components common to those of the first embodiment shown in FIGS. 1 to 4 are denoted by the same reference numerals, and description thereof will be simplified. The second embodiment differs from the first embodiment in that each of the recesses 211a and 211b is formed in a rectangular shape.

That is, the recesses 211a and 211b are
It is formed symmetrically with respect to the nozzle center plane C passing through the center of the nozzle flow path 210, and has a rectangular cross section.

The fluid vibration type flow meter thus configured also has the same operation and effect as the first embodiment.

In the second embodiment, the recess 2
Although the corners of 11a and 211b are formed at right angles, these corners may be formed in an arc shape as shown in FIG. When formed in this manner, the gas flow is smooth even at the corners, and there is an advantage that turbulence is suppressed.

Further, in each of the above embodiments, an example was shown in which a thermal flow sensor was used as the low flow rate sensor 212, but instead of this thermal flow sensor, for example, the temperature of the heat generating section is maintained at a constant temperature. For calculating the flow velocity from the value of the electric power supplied for this purpose, or another type.

Further, in each of the above embodiments, the fluid vibration type flow meter is shown as the LP gas meter. However, the fluid vibration type flow meter is capable of controlling the flow rate of fluids other than the LP gas, such as gases and liquids. Can be measured.

[0042]

According to the first aspect of the present invention, since the enlarged flow path is provided in the nozzle flow path and the low flow rate sensor is provided in the expanded flow path, the narrow flow path is prevented from becoming narrower than the nozzle flow path. be able to. Therefore, low flow sensors of various sizes can be used regardless of the width of the nozzle flow path. Therefore, for example, even if the width of the nozzle flow path is different, a low flow rate sensor having the same dimensions can be used,
There is no need to develop a new low flow sensor according to the width of the nozzle flow path.

Further, by mounting the low flow rate sensor, it is possible to prevent the flow path from becoming narrower than the nozzle flow path, so that the flow of the fluid is smaller than when the low flow rate sensor is provided in the nozzle flow path as it is. Disturbance by the low flow sensor can be prevented. That is, in measuring the flow rate based on the fluid vibration, it is possible to prevent the measurement accuracy from decreasing. Further, also in the measurement by the low flow rate sensor, it is possible to prevent the measurement accuracy from lowering.

According to the second aspect of the present invention, the enlarged flow path portion is formed by the recesses formed symmetrically with respect to the center plane of the nozzle and formed in an arc-shaped cross section. Since the low flow rate sensor is provided in the shape, a symmetric vortex is generated in the flow path around the low flow rate sensor and along the flow path along each concave portion. Then, the vortex circulates in each concave portion to rectify the flow in the nozzle flow path, so that the flow in the nozzle flow path can be reliably prevented from being disturbed by the low flow rate sensor.

According to the third aspect of the present invention, since each recess is formed by the side surface of the same cylinder having the center on the nozzle center surface at the left-right symmetric position, the recess is formed by a drill or the like.
Each recess can be formed simultaneously and simply.

According to the fourth aspect of the present invention, the second aspect is also provided.
As in the invention according to the first aspect, it is possible to reliably prevent the flow from being disturbed by the low flow rate sensor.

According to the fifth aspect of the present invention, since the low flow rate sensor is formed in a columnar shape, a vortex that becomes more symmetrical in the flow path along each concave portion is more accurately generated.
Therefore, it is possible to more reliably prevent the flow from being disturbed by the low flow rate sensor.

[Brief description of the drawings]

FIG. 1 is a front view of a fluid vibration type flow meter shown as a first embodiment of the present invention.

FIG. 2 is a front view of a main part of the fluid vibration type flow meter.

FIG. 3 is a diagram showing an experimental example of the fluid vibration type flow meter, particularly showing a curve obtained by approximating the experimental result by a cubic equation.

FIG. 4 is a diagram showing an experimental example of the fluid vibration type flow meter, particularly showing a curve obtained by approximating the experimental result by a quartic equation.

FIG. 5 is a front view of a main part of a fluid vibration type flow meter shown as a second embodiment of the present invention.

FIG. 6 is an essential part front view showing another example of the fluid vibration type flow meter.

[Explanation of symbols]

 210 Nozzle flow channel 210a One nozzle surface 210b The other nozzle surface 211 Enlarged flow channel portion 211a Recess 211b Recess 212 Low flow rate sensor C Nozzle center surface

Claims (5)

[Claims] 1. A fluid vibration type flow meter for detecting a flow rate based on a fluid vibration of a fluid ejected from a nozzle flow path having a predetermined width, wherein an enlarged flow path portion is provided in the middle of the nozzle flow path. A fluid vibration type flowmeter, wherein a low flow rate sensor is provided in the enlarged flow path portion. 2. The nozzle flow path includes one nozzle surface and the other nozzle surface facing the nozzle surface, and the enlarged flow path portion is formed by a concave portion formed on each of the one and other nozzle surfaces. Each recess is formed symmetrically with respect to the center plane of the nozzle passing through the center of the nozzle flow path, and the cross section is formed in an arc shape, and the low flow rate sensor is coaxial with the enlarged flow path section. The fluid vibratory flow meter according to claim 1, wherein the flow meter is provided. 3. The fluid vibration type flow meter according to claim 2, wherein each of the recesses is formed by side surfaces of the same cylinder having a center on the nozzle center plane and located at left-right symmetric positions. 4. The nozzle flow path is constituted by one nozzle surface and the other nozzle surface facing the nozzle surface, and the enlarged flow passage portion is formed by a recess formed in each of the one and other nozzle surfaces. Each recess is formed symmetrically with respect to the center plane of the nozzle passing through the center of the nozzle flow path, and has a rectangular cross section.The low flow rate sensor is coaxial with the enlarged flow path section. The fluid vibratory flow meter according to claim 1, wherein the flow meter is provided. 5. The fluid vibration type flow meter according to claim 1, wherein the low flow rate sensor is formed in a cylindrical shape.