JP2001074521A - Fluid vibration type flow meter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a measurement accuracy over a wide range for a fluid vibration type flow meter having a micro flow rate measuring portion on the upstream in relation to a nozzle of a fluidic element. SOLUTION: A micro flow rate measuring flow passage 2 having a cross section smaller than a flow passage cross section of a nozzle 11 for measuring low-flow-rate is formed in a fluid guiding part 1 disposed on the upstream in relation to the nozzle 11 of a fluidic element 10. Between the micro flow rate measuring flow passage 2 and a wall portion on the other side in the opening height of the nozzle 11, a vertical partitioning portion 6 for partitioning in the opening width is disposed in a slit-like flow passage 3 formed in the opening height of the nozzle 11. A length (Li) in the flow passage direction of the fluid guiding part 1 is set at least 0.89 times of the opening height (Ws) of the micro flow rate measuring flow passage 2.

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 centered on a gas meter for measuring a fluid flow rate using a fluidic element, and more particularly, to a fluid vibration type flowmeter provided upstream of a nozzle of the fluidic element. In the fluid introduction part, while forming a small flow rate measurement flow path part for small flow rate measurement of a smaller cross-sectional area than the flow path cross-sectional area of the nozzle, the flow path cross section of the fine flow rate measurement flow path part, the opening width direction A rectangular cross section in which the opening height direction is narrowed, formed between the nozzle and the side wall on one end side in the opening height direction of the nozzle, and the opening width of the minute flow rate measurement flow path portion is set to the outlet opening of the nozzle. Wider than the width, the opening height of the minute flow rate measurement flow path portion is set smaller than the opening height of the nozzle, facing the flow path in the minute flow rate measurement flow path portion, in the minute flow rate measurement flow path portion Flow cell that can measure fluid flow rate A flow rate detection end of the nozzle, and the height of the opening of the nozzle coaxial with the nozzle, between the minute flow rate measurement flow path portion of the fluid introduction portion and the wall on the other end side in the opening height direction of the nozzle. A slit-shaped channel portion formed in the vertical direction is provided, and a partition wall portion separating the slit-shaped channel portion and the minute flow rate measurement channel portion in the opening height direction of the nozzle is provided. The slit-shaped flow path portion is formed, and the opposed surface forming the slit-shaped flow channel portion is formed from an outlet flat portion formed in parallel with an outlet side of the slit-shaped flow channel portion with a predetermined opening width and an upstream end surface of the fluid introduction portion. Over the exit plane portion, an outer contour line of the facing surface in a flat cross section viewed from the height direction is formed with an introduction curved surface portion formed by a smoothly continuous curve,
The present invention relates to a fluid vibration type flowmeter provided with a horizontal partition plate for dividing the slit-shaped flow path in the height direction of the nozzle.

[0002]

2. Description of the Related Art Conventionally, in a fluid vibration type flow meter, a fluid element does not oscillate or oscillates in a small flow rate region, making it difficult to measure a small flow rate. To compensate for this, a device provided with a thermal flow sensor is used. In such a fluid vibration type flow meter, the flow sensor is disposed on one inner wall surface in the height direction in the flow path of the nozzle forming the jet of the fluidic element. And the lower limit flow rate in the micro flow rate area could not be reduced sufficiently. This is because the cross section of the nozzle cut at right angles to the flow direction of the nozzle is a rectangle having a large aspect ratio. For example, the ratio of the length of the long side of the cross section of the nozzle (that is, the opening length of the nozzle) to the length of the short side (that is, the opening width of the outlet of the nozzle) is about 10. Thus, the distribution of the flow velocity along the inner wall surface of the nozzle, which is the long side of the flow path cross section of the nozzle having a large aspect ratio, and the distribution of the flow velocity along the side walls at both ends in the height direction of the nozzle, which is the short side, are different.
Since the maximum flow velocity along the short side becomes extremely lower than the maximum flow velocity along the long side, the problem is that the detection level of the flow velocity that can be detected at the side wall on the short side is extremely low.

As a countermeasure for solving this problem, as shown in FIG. 14, a cross section orthogonal to the flow direction of the nozzle forming section 9 is provided at one end in the height direction of the nozzle 11 with a recess at the inner wall surface 11a of the nozzle. It has been proposed to provide an enlarged flow channel portion 11c in which the width of the flow channel is increased by forming a groove (see JP-A-4-32).
No. 6016). The width of the flow detecting end 8a of the flow sensor 8 is set to
As a countermeasure against occupying more than half of the outlet opening width of No. 1, the flow rate detection end 8a is arranged facing the flow path on the side wall surface on the one end side, and at the end of the opposed nozzle inner wall surface 11a, Each of the concave arc-shaped surfaces is formed, and the width of the opening at the one end is about twice the width of the opening at the nozzle outlet.

[0004]

In the above conventional structure, as shown in FIG. 14, there is a problem in that the nozzle inner wall surface 11a is not flat over the entire height. That is,
Due to the uneven width of the jet of the fluid ejected from the nozzle ejection surface 11b, the oscillation of the fluid vibration in the fluidic element may be hindered. As a result, the fluid oscillation becomes unstable, especially in a low flow rate range, causing a problem of increasing the lower limit of the flow rate measurement range.

Accordingly, an object of the present invention is to improve the measurement accuracy of a fluid vibration type flow meter over a wide range.

[0006]

According to a first aspect of the present invention, there is provided a fluid vibration type flow meter according to the first aspect of the present invention, wherein a fluid provided upstream of a nozzle of a fluidic element is provided. In the introduction section, while forming a small flow rate measurement flow path portion for small flow rate measurement of a smaller cross-sectional area than the flow path cross-sectional area of the nozzle, the flow path cross section of the fine flow rate measurement flow path section in the opening width direction On the other hand, in a rectangular cross section in which the opening height direction is narrowed, formed between the nozzle and the side wall at one end side in the opening height direction of the nozzle, the opening width of the minute flow rate measurement flow path portion, the outlet opening width of the nozzle Wider, the opening height of the micro flow rate measurement flow path portion,
Set smaller than the opening height of the nozzle, facing the flow path in the micro flow rate measurement flow path section, provided a flow detection end of a flow sensor capable of measuring the fluid flow rate in the micro flow rate measurement flow path section, A slit-shaped flow formed in the direction of the height of the opening of the nozzle coaxially with the nozzle, between the minute flow rate measurement flow path portion of the fluid introduction portion and the wall on the other end side in the direction of the opening height of the nozzle. A channel portion is provided, and a partition wall portion is formed between the slit-shaped flow channel portion and the minute flow rate measurement flow channel portion so as to separate them in the height direction of the opening of the nozzle. The opposite surface forming the, the outlet flat portion formed in parallel with the outlet side of the slit-shaped channel portion with a predetermined opening width, from the upstream end face of the fluid introduction portion to the outlet flat portion, from the height direction The outline of the facing surface in the plane section seen is smooth. In the fluid vibration type flowmeter, which is formed by an introduction curved surface portion formed by a continuous curve or a horizontal partition plate portion that divides the slit-shaped flow passage portion in the opening height direction of the nozzle, A vertical partition plate portion that is divided in the opening width direction of the slit-shaped channel portion is provided in the slit-shaped channel portion, and the length of the fluid introduction portion in the channel direction is,
The point is that it is formed so as to be at least 0.89 times the opening height of the micro flow rate measurement flow path section.

According to a second aspect of the present invention, the length of the outlet flat portion in the flow path direction in the first characteristic configuration is 1 mm.
It is even better if the distance is set to not less than 3 mm (second characteristic configuration).

According to a third aspect of the fluid vibration type flow meter according to the present invention, there is provided the fluid vibration type flow meter according to the first aspect, wherein the flow path is divided in a width direction of the slit-shaped flow path. The point is that a vertical partition plate portion is provided in the slit-shaped channel portion.

[Operation and effect of each characteristic configuration]

The first aspect of the fluid vibration type flow meter according to the present invention is as follows.
According to the characteristic configuration, the measurement error in the measurement range can be kept within a predetermined range while stabilizing the flow measurement in the low flow rate region. That is, by providing the vertical partition plate portion in the slit-shaped flow channel portion, the fluid rectified in a narrow width is directed toward the nozzle, and is introduced from a plurality of positions dispersed in the width direction of the outlet opening of the nozzle. It is possible to suppress disturbance of the flow of the fluid. In particular, by setting the length of the fluid introduction section in the flow path direction as in the first characteristic configuration, it is possible to suppress the bias generated in the flow of the fluid flowing into the nozzle in the low flow rate region, and to reduce the flow rate in the fluidic element. Since the oscillation of the fluid vibration in the flow rate range can be prevented from becoming unstable, the flow rate measurement with stable measurement accuracy can be performed in the low flow rate range. This is shown in FIG. 13 in which the result of verifying the measurement accuracy of the fluid vibration type flow meter by changing the length of the fluid introduction unit in the flow path direction is arranged as a curve, as shown in FIG. This is because it has been found that if the length in the flow path direction is less than 0.89 times the opening height of the minute flow rate measurement unit, the flow rate measurement error will exceed 3%.

Regarding the point that the upper limit of the length of the fluid introduction portion in the flow path direction is not set, the height of the opening of the minute flow rate measurement portion can be increased by increasing the length of the fluid introduction portion in the flow direction. Up to about 1.2 times, the flow rate measurement error is gradually improved, and if the length is further increased, the size of the fluid vibration type flow meter is inevitably increased. This is because the flow rate measurement error is within a sufficiently satisfactory range. In particular, if the ratio of the length of the fluid introduction section in the flow path direction to the opening height of the minute flow rate measurement section is 1.02 or more, the flow rate measurement error can be maintained at 2% or less. is there. Here, in the first characteristic configuration, the length of the exit plane portion is set to 1
mm or more can suppress turbulence in the flow of fluid flowing out of the slit-shaped flow path toward the nozzle,
If the length of the outlet flat part is too long, the flow resistance in the slit flow path part increases, which is not preferable. To set the length of the fluid introduction part in the flow direction preferably 3 mm
It is preferable to set the following.

The third aspect of the fluid vibration type flow meter according to the present invention is as follows.
According to the characteristic configuration, similarly to the first characteristic configuration, it is possible to stabilize the flow rate measurement in the low flow rate range and keep the measurement error in the measurement range within a predetermined range.
That is, by providing the vertical partition plate portion in the slit-shaped flow channel portion, the fluid rectified in a narrow width is directed toward the nozzle, and is introduced from a plurality of positions dispersed in the width direction of the outlet opening of the nozzle. It is possible to suppress disturbance of the flow of the fluid.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a fluid vibration type flow meter according to the present invention will be described. FIG. 1 is a plan sectional view showing an example of a gas meter using the fluid vibration type flow meter according to the present invention, FIG. 2 is a plan view sectional view of the fluid vibration type flow meter shown in FIG. 1, and FIG. FIG. 4 is a partially cutaway perspective view of the nozzle forming portion, FIG. 4 is a plan sectional view of the slit-shaped flow channel portion, and FIG. 5 is a perspective view of the fluid introduction portion as viewed from the fluid inflow side. 14 that are the same as or similar to the elements in FIG. 14 used in the above-described prior art are denoted by the same or related reference numerals as those in FIG. 14 and described in detail. Is partially omitted.

A gas meter which is an example using the above-mentioned fluid vibration type flow meter is a No. 6 meter, and as shown in FIG. 1, a fluid vibration type flow meter according to the present invention which measures a flow rate using a fluidic element 10. The flow meter M is used. The gas meter 20 is configured such that the inflow direction I of the fluid f to be measured is 180 ° opposite to the outflow direction O. That is, a fluid f such as gas or water flows in from the apparatus inlet 21, and the curved path 22 provided with the pressure fluctuation absorbing mechanism 25.
Through the shut-off valve section 23. And this shutoff valve part 23
The fluid f having passed through flows into the storage part 24. The fluid f that has flowed into the storage section 24 is configured to flow out of the device outlet 26 via the fluid vibration type flow meter M. The fluid f flowing into the fluid vibration type flow meter M is
The fluid flows into the nozzle 11 from the fluid introduction path 9a via the fluid introduction unit 1 provided in the nozzle forming unit 9 that forms the nozzle 11 of the fluidic element 10. This nozzle 11
The fluid f ejected from the fluid element 10 into the fluidic element 10 changes the direction of the jet and vibrates, while the flow channel expanding portion 15 and the throttle channel portion provided downstream of the nozzle jetting surface 11b. It flows out to the device outlet 26 through the device 16. The fluid vibration type flow meter M has the nozzle 1
A pair of fluid vibration detecting ends 12 for detecting the vibration of the jet flow are arranged on both sides of the nozzle 1 and near the nozzle jetting surface 11b. The fluid vibration detection end 12 is an opening formed to have a small diameter, and communicates with a fluid vibration detection sensor having a pair of pressure introducing portions to detect fluid vibration.

As shown in FIG. 2, for example, the shape of the fluidic element 10 is such that the enlarged flow path portion 15 is formed between the enlarged flow path forming members 14 arranged with the flow path axis Z as the axis of symmetry. The nozzle 1 is located at the center of the flow path of the flow path enlargement section 15.
A target 13 for preventing the jet flowing from 1 from traveling straight is provided, and the throttle channel portion 16 is provided downstream of the channel expansion portion 15. The nozzle 11 has two inner side surfaces in the nozzle width direction that are parallel to the flow path axis Z.
1a, and the nozzle ejection surface 11b is
Are formed in a state orthogonal to. An inner surface of the enlarged flow path forming member 14 faces the flow path axis Z side,
A circular arc portion 14a formed by a pair of circular arcs having a center on a parallel straight line spaced a predetermined distance downstream from the nozzle ejection surface 11b and having a center equidistant from the flow channel axis Z.
And a straight line portion 14b formed by a tangent line on the side of the nozzle ejection surface 11b that is close to the flow path axis Z on the outside of the arc.
And are connected smoothly. The arc portion 14a
At the rear end, a discharge arc 14c is formed to smoothly connect the arc 14a to the throttle passage 16.
The target 13 is arranged at a position separated by a predetermined distance from the nozzle ejection surface 11b, and has an effect of stably switching the flow direction of the jet flow within the flow rate measurement range. By the way, in the flow rate region on the small flow rate side, the fluid f of the return flow tends to accumulate in the vicinity of the nozzle ejection surface 11b in response to the ejection from the nozzle 11 of the fluidic element 10, which hinders the fluid oscillation. In order to avoid this, the enlarged flow path forming member 14 is separated from the nozzle ejection surface 11b to form a relief path 17 on the back side of the enlarged flow passage forming member 14, and the return flow is transferred to the nozzle ejection surface 11b. A branch is made in the vicinity, and a part of the return flow is caused to flow out from the relief path 17 as a branch flow.

In the above fluidic element 10,
The jet ejected from the nozzle ejection surface 11b is the target 1
3 and a main stream which flows out of the throttle flow path portion 16 while bypassing the side of the flow path 3, and a portion which branches off from the main flow of the jet flow and forms a downstream portion of the flow path enlargement portion 15 or forms the throttle flow path portion 16. By colliding with the cross-section, a return flow returns to the nozzle 11 side in the flow path along the inner surface of the enlarged flow path forming member 14, and this return flow flows back toward the nozzle ejection surface 11b, A fluid energy component is applied to the vicinity of the nozzle ejection surface 11b in a direction perpendicular to the direction of straight flow of the jet and opposite to the direction in which the jet sways, and the jet sways in the opposite direction. By repeating this,
A fluid oscillation occurs, and the oscillation cycle is determined by the fluid f
Is inversely proportional to the flow rate. Therefore, the nozzle ejection surface 11b
Since the pressure difference between the pair of fluid vibration detection ends 12 disposed in the vicinity is proportional to the square of the flow velocity of the jet, the fluid vibration is detected by the capacitance type pressure vibration sensor, and the frequency is measured. By doing so, an attempt is made to measure the flow rate of the fluid f flowing through this flow path.

The nozzle forming portion 9 is formed from the nozzle inner wall surface 11a side.
As shown in FIG. 3 when viewed obliquely, the fluid introduction path 1a is located in the fluid introduction passage 9a located on the upstream side of the nozzle forming section 9.
(In the figure, as shown, a part of the side wall of the nozzle forming portion 9 is cut away.). The fluid introduction section 1 has a fluid f in a small flow rate region having a smaller cross-sectional area than the flow path cross-sectional area of the nozzle 11 and in which the oscillation of the fluid vibration in the fluidic element 10 becomes unstable.
Forming a minute flow rate measurement flow path 2 for measuring the flow rate of the nozzle 11, and between the minute flow rate measurement flow path 2 and the wall on the other end side in the opening height direction of the nozzle 11, The slit-shaped flow path 3 is formed over the opening height direction, and the slit-shaped flow path 3 is divided to form a plurality of rectification flow paths 3s. A partition wall 5 is formed between the measurement flow path 2 and the separation wall 5 in the height direction of the opening of the nozzle 11.

A flow sensor 8 capable of measuring the flow rate of the fluid f flowing in the minute flow rate measurement flow path section 2 in the minute flow rate area is provided in the minute flow rate measurement flow path section 2. 2, the flow rate detecting end 8a of the flow sensor 8 is arranged on the side wall surface of the minute flow rate measuring flow path section 2 in the height direction so as to face the flow path. The outlet opening height of the minute flow rate measurement flow path 2 is smaller than the opening height of the nozzle 11 (see FIG. 3), and the opening width (Ws) of the minute flow rate measurement flow path 2 is It is set wider than the outlet opening width (Wn) (see FIG. 4). The opening width (Ws) of the micro flow rate measurement flow path 2 and the nozzle 11
Is set so as to satisfy 2.2 ≦ Ws / Wn ≦ 2.8.

Regarding this dimensional relationship, if Ws <Wn × 2.2, the maximum flow velocity near the wall surface where the flow rate detecting end 8a of the flow sensor 8 is arranged may not be sufficiently obtained, and in the minute flow rate range. There is a possibility that the flow rate detection sensitivity becomes insufficient, which is not preferable. In addition, if Ws> Wn × 2.8, the width of the nozzle forming section 9 becomes too large, and the fluid vibration type flow meter M It may not be very desirable from the viewpoint of miniaturization.

As shown in FIG. 4, the slit-shaped flow passage 3 is formed in the direction of the height of the opening of the nozzle 11 and is arranged coaxially with the nozzle 11. The opposing surface 4 forming the slit-shaped flow path portion 3 includes an outlet flat surface portion 4 a formed parallel to the outlet side of the slit-shaped flow path portion 3 with a predetermined opening width, and an upstream end surface of the fluid introduction portion 1. From 1a to the exit plane portion 4a, a cylindrical surface formed with an introduction portion radius of curvature (Rs) in which the outline of the facing surface 4 in a flat cross section viewed from the height direction is formed by a smoothly continuous curve. It is formed by the introduction curved surface portion 4b. Then, the length (Lf) of the outlet flat portion 4a in the flow path direction is set to 1 mm or more and 3 mm or more.
mm or less. Length in this flow direction (Lf)
Is less than 1 mm, the flow of the fluid f flowing out of the outlet flat portion 4a is caused to cause the rectification effect to be easily impaired, or the pressure loss due to the divergence may be increased. When the length (Lf) in the flow path direction exceeds 3 mm, the pressure loss increases, and when the pressure loss increases, the inflow pressure of the fluid f at the nozzle inlet of the fluidic element 10 decreases to improve the fluid vibration. Since the effect may be impaired, it is not preferable to further increase the length (Lf) in the flow path direction.

Further, as a feature of the present invention, the vertical partition plate portion 6 is provided.
Is provided in the slit-shaped flow path portion 3 so as to be coaxial with the nozzle 11 and inserted so as to be divided in the opening width direction of the slit-shaped flow path portion 3 to form the rectification flow path 3s. It is. Further, the slit-shaped flow path portion 3 is provided with a horizontal partition plate 7 that divides the slit-shaped flow path portion 3 in the opening height direction of the nozzle 11, the length of the fluid introduction portion 1 in the flow direction ( Li) and formed in the same flow direction length as that of Li) (for example, see FIG. 5). The opening width of the slit flow path 3 is equal to the outlet opening width (Wn) of the nozzle 11, but the opening width of the slit flow path 3 is divided by the vertical partition plate 6. The opening widths of the plurality of rectification channels 3s are totaled.

As described above, the length (Li) of the fluid introduction section 1 in which the rectifying flow path section 3 is formed is 0% of the opening width (Ws) of the minute flow rate measurement flow path section 2. .89 times or more. Here, the length (Li) of the fluid introduction part 1 in the flow path direction is defined by the radius of curvature (Rs) of the introduction part and the length (L) of the outlet flat part 4a in the flow path direction.
There is a relationship of Li = Rs + Lf with respect to f). By forming in this manner, for example, as shown in FIG. 13, the maximum error width (ΔE) of the flow measurement value is obtained.
Can be kept within 3% of the measurement reference value.

The fluidic element 10 including the nozzle 11 and the fluid introduction section 1 described above are made of synthetic resin. This makes use of the point that the dimensional change due to the use temperature is small, and is selected based on the shape and the number of products manufactured. In particular, the fluid introduction part 1 is precisely machined out by machining. This is because it is difficult and the mold for molding is easier to manufacture.

FIG. 5 is a perspective view of the fluid introducing portion 1. In this example, one vertical partition plate portion 6 and four horizontal partition plate portions 7 are provided to This shows an example in which the road section 3 is divided into ten parts. In the fluid introduction path 9a in which the fluid introduction unit 1 configured as described above is arranged, the flow velocity distribution of the fluid f at the flow path outlet of the fluid introduction unit 1 is indicated by, for example, the length of an arrow in FIG. That is, the maximum flow velocity in the flow velocity distribution of the fluid f in the opening width direction of the nozzle 11 along the wall on one end side in the opening height direction of the nozzle 11 in the minute flow rate measurement flow path section 2 is the highest. In addition, the flow velocity distribution of the fluid f in the opening height direction of the nozzle 11 is substantially the same in each of the rectification channels 3 s into which the minute flow rate measurement channel portion 2 and the slit-shaped channel portion 3 are divided. .

To explain this point in detail, generally, fluid has a property of flowing along a wall surface due to the Coanda effect. Therefore, rather than increasing the length of the exit plane portion 4a, the rectification effect is increased by arranging the vertical partition plate portion 6 and increasing the number of side wall surfaces. However, as shown in the figure, if the flow path has a rectangular cross section, the flow along both side walls is discontinuous at the contact corners of the adjacent side walls, so that the flow velocity is low at both the contact corners. However, since the vertical partition plate portion 6 forms a side wall surface facing the outlet flat portion 4a to form the rectification flow path 3s, the flow of the fluid f is substantially evenly distributed to both outlet flat portions 4a, and the slits are formed. Channel 3
The flow velocity distribution symmetrical in the opening width direction can be formed. Accordingly, as shown in FIG. 7, the fluid f flowing out of the fluid introduction part 1 symmetrically in the opening width direction of the slit-shaped flow path part 3 at a substantially uniform flow velocity to the downstream nozzle 11 via the fluid introduction path 9a. Therefore, the distribution of the flow can be equally distributed to the left and right nozzle inner wall surfaces 11a.

The flow of the fluid f evenly distributed as described above is applied to the fluid introduction passage 9a up to the nozzle 11.
As a result, the flow velocity distribution of the fluid f becomes substantially uniform over the entire area in the height direction of the nozzle 11,
Oscillation of the fluid vibration in the fluidic element 10 is performed smoothly. As described above, the flow rate distribution of the fluid f is made uniform by dividing the slit-shaped flow path portion 3 into the rectification flow paths 3s.
By arranging one vertical partition plate part 6 in the slit-shaped flow path part 3, the rectification flow path 3s divided by the horizontal partition plate part 7 can be doubled. The horizontal partition plate portion 7 not only functions as a partition wall in the opening height direction of the slit flow channel portion 3 described above, but also connects the opposing surfaces 4 of the slit flow channel portion 3 to each other. It also serves as a reinforcing rib.

[Another Embodiment] Another embodiment not described in the above embodiment will be described below.

<1> In the above embodiment, the gas meter 20 of No. 6 has been described as an example of the fluid vibration type flow meter M. However, the fluid vibration type flow meter according to the present invention is not limited to the above example. The present invention can be applied to any fluid vibration type flow meter using a fluidic element, such as a gas meter of another size, a flow meter having a different target fluid, and the like, and has the above-described effects. The structure of the fluidic element 10 is not limited to the illustrated one, and any fluidic element structure such as one without the throttle channel portion 16 and one without the escape path 17 can be adopted.

<2> In the above embodiment, the example in which the horizontal partition plate portion 7 is formed to have the same length in the flow direction as the length of the fluid introduction portion 1 in the flow direction has been described. The partition plate portion 7 may be formed to have the same flow direction length as the vertical partition plate portion 6, or the flow direction length of the fluid introduction portion 1 and the flow direction direction of the vertical partition plate portion 6. It may be formed to have an intermediate length in the flow path direction.

<3> In the above embodiment, the fluid introduction part 1 is described as being made of synthetic resin, but it may be made of another material, such as die-cast aluminum. Alternatively, it may be a precision cast product, or a metal product formed by casting or forging. In addition, if it does not mind cost, a thing made of fine ceramics is preferred for improvement of accuracy.

<4> In the above embodiment, an example in which one vertical partition plate 6 is provided has been described. However, two or more vertical partition plates 6 may be provided. In this case, it is preferable that the opening widths of the divided rectifying flow passages 3s of the slit-shaped flow passage portion 3 are equal to each other, and the sum of those opening widths is equal to the outlet opening width (Wn) of the nozzle 11. ) Is preferably formed. Further, it has been described that it is preferable to provide four to six horizontal partition plates 7, but more horizontal partition plates 7 may be formed. The opening height of the slit-shaped flow path portion 3 is sufficient;
The number of sheets may be increased as long as an appropriate interval can be provided. Note that the horizontal partition plate 7 may be omitted as long as the flow velocity distribution in the opening height direction of the slit flow path 3 can be flattened.

[0032]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
About the specific example applied to No. gas meter, the flow rate measurement error of each meter was investigated. The specifications of the applied fluidic element are as shown in Table 1. The aspect ratio of the opening of the nozzle is about 9.23.

[0033]

[Table 1]

A fluid introduction unit 1 arranged upstream of the fluidic element 10 provided in the fluid vibration type flow meter subjected to the test
The flow rate measurement error of the fluid vibration type flow meter in which the length (Li) of the flow path direction was changed between 9 to 13 mm was examined. As an example, the length (Li) in the flow direction is 9.0,
A fluid vibration type flowmeter having 10.0, 11.0, 12.0, and 13.0 mm was prepared. The latter is an example of conventional dimensions. In each embodiment, the length (Li) of the fluid introduction unit 1 in the channel direction and the opening width (W) of the minute flow rate measurement channel unit 2 are described.
The ratio to s) is as shown in Table 2.

[0035]

[Table 2]

For each of the No. 6 gas meters incorporating the fluid inlet shown in each of the above examples, 150 liters / h to 7
For a range over 200 liters / h, the measurement error (E) was examined by flowing air instead of city gas. The results are shown in FIGS. FIG. 8 shows the result of the error measurement for the first embodiment, and FIG. 9 shows the error measurement result for the second embodiment.
0 shows an error measurement result for Example 3, FIG. 11 shows an error measurement result for Example 4, and FIG. 12 shows an error measurement result for Example 5. FIG. 13 shows the flow rate measurement range (that is, 300 to 60) obtained from the error measurement results of each of Examples 1 to 5 described above.
The maximum error width (Δ between the maximum error on the plus side and the maximum error on the minus side within the range of 00 ml / h)
E).

As is clear from the comparison of the figures, the opening width (W) of the minute flow rate measurement flow path section 2 having a length (Li) in the flow path direction is obtained.
If the ratio (Li / Ws) to s) is 0.9 to 1.3 (within the range of the embodiment), it is not less than 300 l / h and 60
Within the range of 00 liter / h or less (flow rate measurement range Rd), the maximum error width (ΔE) is all within 3%. However, as is clear from FIG.
i / Ws) is less than 0.89, the maximum error width (ΔE) exceeds 3%, and the ratio (Li / Ws)
It can be seen that the maximum error width (ΔE) increases as s) decreases. When the ratio (Li / Ws) is about 1.02 or more, the maximum error width (ΔE) becomes 2% or less, and when the ratio (Li / Ws) becomes 1.2 or more, the maximum error width (ΔE) becomes 1.2% or more. The error width (ΔE) is 1.5% or less. Looking at the tendency, it was found that even when the ratio (Li / Ws) exceeded 1.3, the maximum error width (ΔE) maintained a sufficiently low value. From the above, the length in the channel direction (L
It was found that when the ratio (Li / Ws) to the opening width (Ws) of the micro flow rate measurement flow path section 2 in (i) was in the range of 0.89 or more, it surely fell within the legal error range. 8 to 1
From the results shown in FIG. 2, the ratio (Li / Ws) was 0.9 to
If it is within the range of 1.3, there is no practical problem when applied to a gas meter. 8 to 12, the legal error limit (reference value ± 1.5%) is indicated by a dashed line.

[Brief description of the drawings]

FIG. 1 is a cross-sectional plan view showing an example of a gas meter according to the present invention.

FIG. 2 is a cross-sectional plan view illustrating a specific configuration of the fluid vibration type flow meter shown in FIG.

FIG. 3 is a partially cutaway perspective view of a nozzle forming portion illustrating an example of a configuration according to the present invention.

FIG. 4 is a cross-sectional plan view for explaining the dimensional relationship of the rectifying flow path according to the present invention.

FIG. 5 is a perspective view of a fluid introduction unit showing an example of a flow regulating channel unit according to the present invention.

FIG. 6 is a plan cross-sectional view of a main part of the fluid vibration type flow meter for explaining the operation of the rectifying flow path according to the present invention.

FIG. 7 is a perspective view of a fluid introduction part for explaining the operation of the rectifying flow path part according to the present invention.

FIG. 8 is a diagram showing a measurement error in an example of the fluid vibration type flow meter according to the present invention.

FIG. 9 is a diagram showing a measurement error in another example of the fluid vibration type flow meter according to the present invention.

FIG. 10 is a diagram showing a measurement error in another example of the fluid vibration type flow meter according to the present invention.

FIG. 11 is a diagram showing a measurement error in another example of the fluid vibration type flow meter according to the present invention.

FIG. 12 is a diagram showing a measurement error in another example of the fluid vibration type flow meter according to the present invention.

FIG. 13 is a diagram illustrating the effect of the embodiment of the present invention.

FIG. 14 is a vertical cross-sectional view of a nozzle for explaining a conventional flow sensor arrangement.

[Explanation of symbols]

 Reference Signs List 1 fluid introduction part 1a upstream side surface of fluid introduction part 2 minute flow rate measurement part 3 minute flow rate measurement flow path part 4 opposing surface of slit flow path part 4a exit plane part of opposing surface 4b introduction curved surface part of opposing surface 5 partition wall Part 6 Vertical partition plate part 7 Horizontal partition plate part 8 Flow sensor 8a Flow detecting end 10 Fluidic element 11 Nozzle Li Length of fluid introduction part in flow direction Ws Opening width of micro flow measurement part

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Makoto Okabayashi 4-1-2, Hirano-cho, Chuo-ku, Osaka-shi, Osaka Inside Osaka Gas Co., Ltd. (72) Shuichi Okada 4-chome, Hirano-cho, Chuo-ku, Osaka-shi, Osaka 1-2-2 Inside Osaka Gas Co., Ltd. (72) Inventor Keiichi Tomoda 4-7-131 Nishiiwata, Higashiosaka-shi, Osaka Inside Kinmon Seisakusho Co., Ltd. (72) Inventor Masanari Imaki Nishiiwata, Higashi-Osaka-shi, Osaka 4-7-31 Inside Kinmon Manufacturing Co., Ltd. (72) Inventor Eiji Nakamura 2-10-16 Higashiobashi, Higashi-Nari-ku, Osaka-shi, Osaka Inside Kansai Gas Meter Co., Ltd. (72) Inventor Masanobu Namimoto Osaka-shi, Osaka 2-10-16 Higashiobashi, Nari-ku Kansai Gas Meter Co., Ltd. F-term (reference) 2F030 CA10 CC13 CD13 CF01 CF05 CF11 CF20

Claims (3)

[Claims] 1. A micro flow rate measuring flow path section for measuring a small flow rate having a smaller cross-sectional area than a flow path cross-sectional area of a nozzle is formed in a fluid introduction section provided on an upstream side of a nozzle of a fluidic element. Along with, the flow cross section of the micro flow rate measurement flow path portion,
A rectangular cross-section in which the opening height direction is narrowed with respect to the opening width direction, formed between the nozzle and the side wall on one end side in the opening height direction of the nozzle; The opening height of the micro flow rate measurement flow path is wider than the outlet opening width of the nozzle, and the opening height of the micro flow rate measurement flow path is set smaller than the opening height of the nozzle. A flow rate detection end of a flow sensor capable of measuring a fluid flow rate in the flow path section is provided, between the minute flow rate measurement flow path section of the fluid introduction section and the wall on the other end side in the opening height direction of the nozzle. A slit-shaped flow path formed coaxially with the nozzle in the direction of the opening height of the nozzle, and between the slit-shaped flow path and the micro flow rate measurement flow path, the Form a partition wall separated in the height direction of the opening, and The opposing surface forming the lit-shaped flow channel portion, an outlet flat portion formed parallel to the outlet side of the slit flow channel portion with a predetermined opening width, and from the upstream end face of the fluid introduction portion to the outlet flat portion. And an introduction curved surface portion in which a contour line of the facing surface in a flat cross section viewed from the height direction is formed by a smoothly continuous curve, and the slit-shaped flow passage portion in the opening height direction of the nozzle. A fluid vibration type flowmeter provided with a dividing horizontal partition plate portion, wherein a vertical partition plate portion that divides the slit-shaped flow channel portion in an opening width direction is provided in the slit-shaped flow channel portion, and the fluid A fluid vibration type flow meter formed so that the length (Li) of the introduction section in the flow path direction is 0.89 times or more the opening height (Ws) of the micro flow rate measurement flow path section. 2. The length of the outlet flat portion in the flow path direction is 1
The fluid vibration type flow meter according to claim 1, wherein the flow rate is set to be not less than 3 mm and not more than 3 mm. 3. A small flow rate measurement flow path portion for measuring a small flow rate having a smaller cross-sectional area than the flow path cross-sectional area of the nozzle is formed in a fluid introduction section provided on an upstream side of a nozzle of the fluidic element. Along with, the flow cross section of the micro flow rate measurement flow path portion,
A rectangular cross-section in which the opening height direction is narrowed with respect to the opening width direction, formed between the nozzle and the side wall on one end side in the opening height direction of the nozzle; The opening height of the micro flow rate measurement flow path is wider than the outlet opening width of the nozzle, and the opening height of the micro flow rate measurement flow path is set smaller than the opening height of the nozzle. A flow rate detection end of a flow sensor capable of measuring a fluid flow rate in the flow path section is provided, between the minute flow rate measurement flow path section of the fluid introduction section and the wall on the other end side in the opening height direction of the nozzle. A slit-shaped flow path formed coaxially with the nozzle in the direction of the opening height of the nozzle, and between the slit-shaped flow path and the micro flow rate measurement flow path, the Form a partition wall separated in the height direction of the opening, and The opposing surface forming the lit-shaped flow channel portion, an outlet flat portion formed parallel to the outlet side of the slit flow channel portion with a predetermined opening width, and from the upstream end face of the fluid introduction portion to the outlet flat portion. And an introduction curved surface portion in which a contour line of the facing surface in a flat cross section viewed from the height direction is formed by a smoothly continuous curve, and the slit-shaped flow passage portion in the opening height direction of the nozzle. A fluid vibration type flowmeter provided with a horizontal partition plate portion to be divided, wherein a vertical partition plate portion to be divided in an opening width direction of the slit flow channel portion is provided in the slit flow channel portion. Type flow meter.