JP2709202B2 - Fluidic flow meter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluid flow meter for detecting a flow rate by detecting an alternating pressure wave generated by a vibration phenomenon of a fluid such as gas ejected from an ejection nozzle into a flow path.

[0002]

2. Description of the Related Art A fluidic flow meter installed in a general household or the like for measuring a gas flow rate is disclosed in, for example,
It is known from JP-A-313018 and JP-A-1-250725.

[0003] In this fluidic flow meter, an ejection nozzle is provided in a partition partitioning an upstream side flow path and a downstream side flow path of the flow path, and a fluidic element provided in the downstream flow path from the ejection nozzle is provided. When the fluid is ejected, the ejected fluid flows, for example, along the right side wall due to the Coanda effect.

[0004] A part of the fluid flowing to the right side wall becomes a return fluid, and the fluid energy of the return fluid is applied to the ejected fluid, so that the ejected fluid flows along the left side wall. A part of the fluid flowing to the side wall becomes a return fluid, and the fluid energy of the return fluid is applied to the ejection fluid, so that the ejection fluid flows again along the right side wall.

That is, an alternating pressure wave is generated by the vibration phenomenon of the fluid ejected from the ejection nozzle into the flow path. The alternating pressure wave is detected by the piezoelectric film sensor, and the flow rate is calculated from the frequency to detect the flow rate of the fluid.

[0006]

By the way, in the fluidic flow meter, the fluid flowing from the inlet body of the case body is guided to the ejection nozzle via the upstream flow path, and the fluid ejected from the ejection nozzle is Although it flows into the fluidic element, the sensitivity of the flow velocity sensor is poor in the micro flow rate range,
High-precision measurement is not possible.

In view of the above, a plurality of partition plates are provided at equal intervals inside the jet nozzle to prevent the fluid flowing from the upstream flow path to the downstream flow path from concentrating at the center of the jet nozzle. Dividing is performed by a plate.

When the partition plate is provided in the ejection nozzle in this way, the sensitivity of the flow velocity sensor can be increased to some extent. However, since the end of the partition plate is perpendicular to the direction of flow of the fluid, the fluid cannot flow through the partition plate. A vortex is generated at the end, causing turbulence. For this reason, the performance of the fluidic element deteriorates, and there is a problem that accurate measurement cannot be performed.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances. It is an object of the present invention to suppress the adverse effect on the performance of a fluidic element and to improve the measurement sensitivity of a flow rate sensor. It is an object of the present invention to provide a fluidic flow meter capable of accurate measurement even in the above.

[0010]

According to the present invention, in order to achieve the above object, a first aspect of the present invention is to provide a flow path main body constituting a flow path, wherein a partition is provided and an upstream flow path and a downstream flow path are separated. The partition is provided with an ejection nozzle for ejecting the fluid of the upstream channel to the downstream channel, and a plurality of partition plates are provided inside the ejection nozzle in parallel with the bottom surface of the channel main body and at a predetermined interval. Among these partition plates, the interval between the uppermost partition plate and the upper surface of the ejection nozzle and the interval between the lowermost partition plate and the lower surface of the ejection nozzle are set between the partition plates. It is characterized in that it is larger than the interval.

According to a second aspect of the present invention, a taper portion that becomes gradually thinner toward the end is provided at one end of the partition plate located on the inlet side of the ejection nozzle and the other end of the partition plate located on the exit side of the ejection nozzle. It is characterized by having been formed.

According to a third aspect of the present invention, the tapered portion at the end of the partition plate is a taper which is gradually inclined toward the end toward the center of the ejection nozzle, and the fluid passing through the ejection nozzle is dispersed above and below the ejection nozzle. The taper portion at the other end of the partition plate is tapered so as to gradually disperse in the upper and lower portions of the ejection nozzle toward the end portion, so that the fluid ejected from the ejection nozzle is vertically dispersed. A fourth aspect of the present invention is characterized in that the tapered portion of the partition plate is a straight or curved taper formed by chamfering.

[0013]

The fluid flowing from the upstream flow path to the downstream flow path via the ejection nozzle is divided by the partition plate provided inside the ejection nozzle, and the fluid flows to the lower portion of the ejection nozzle having the flow rate sensor. Is concentrated and circulates toward the fluidic element, and the sensitivity of the flow velocity sensor increases, so that accurate measurement can be performed even with a small flow rate.

[0014]

An embodiment of the present invention will be described below with reference to the drawings.

FIGS. 3 and 4 show the whole of a fluidic flow meter, and 11 is a case. This case 1
1 is a rectangular box-shaped case body 12 and this case body 12
And a lid 13 that closes the opening of the cover.

At the upper part of the case body 12, the gas inlet 1
4 is provided, and a gas outlet body 15 is provided at a lower portion. Further, a fluidic element 17 to be described later is installed at a lower portion inside the case 11, and a shutoff valve 18 is installed at an upper portion.

The fluidic element 17 will be described. Reference numeral 19 denotes a flow path main body formed by die casting or the like.
The flow path 22 is configured by being closed by the lid 21 through the opening 0. The flow path 22 is partitioned by a partition 23, the upstream flow path 24 communicates with the gas inlet 14, and the downstream flow path 25 communicates with the gas outlet 15.

A valve seat 26 is provided in the middle of the upstream flow passage 24, and the valve body 27 of the shut-off valve 18 faces the valve seat 26. That is, the flow path 22 can be shut off by the shut-off valve 18 when the seismic sensor or the like detects an abnormality.

A jet nozzle 28 is provided on the partition wall 23 of the flow path main body 19. The ejection nozzle 28 has a slit shape that opens over the entire depth direction of the flow path main body 19, and has projections 28 a and 28 b that protrude into the upstream flow path 24 on both side edges in the longitudinal direction of the nozzle main body. The length has been extended.

As shown in FIGS. 1 and 2, a plurality of partition plates 29 are provided inside the ejection nozzle 28. These partition plates 29 are parallel to the bottom surface of the flow path main body 19, and the partition plates 29 are arranged at equal intervals. That is, the bottom surface of the flow path main body 19 is lower,
Assuming that 1 is the upper part, the plurality of partition plates 29 are arranged at equal intervals in the vertical direction.

Further, of these partition plates 29, the distance a between the uppermost partition plate 29U and the upper surface of the jet nozzle 28
The distance c between the lowermost partition plate 29L and the lower surface of the ejection nozzle 28 is formed to be larger than the distance b between the partition plates 29, and is set to have a relationship of a> b, c> b. Then, the lower surface of the ejection nozzle 28, that is, the partition plate 2
The flow velocity sensor 40 to be described later is provided in a passage with a large interval from the 9L.
Is provided.

Further, the partition plate 29 is formed such that the inlet side of the jet nozzle 28 is wide and the outlet side is narrow along the inner surface shape of the jet nozzle 28. Of the plurality of partition plates 29, the end of the central one partition plate 29 located on the inlet side of the ejection nozzle 28 is formed with a tapered portion 30a that becomes gradually thinner toward the end by chamfering on both sides. Have been.

The end of the partition plate 29 disposed above the center partition plate 29, which is located on the inlet side of the jet nozzle 28, is gradually thinned toward the end by chamfering the upper surface side on one side. A taper portion 30b is formed, and the end located on the inlet side of the ejection nozzle 28 of the partition plate 29 disposed at the lower portion is tapered such that the lower surface side is chamfered on one side so that the thickness gradually decreases toward the end portion. A portion 30c is formed.

Further, the end of the central one partition plate 29 located on the outlet side of the ejection nozzle 28 has a tapered portion 3 which becomes gradually thinner toward the end by chamfering on both sides.
1a is formed.

The end of the partition plate 29 disposed above the central partition plate 29, which is located on the outlet side of the jet nozzle 28, is gradually thinned toward the end by chamfering the lower surface of the partition plate 29 on one side. The end of the partition plate 29 disposed at the outlet side of the ejection nozzle 28 is formed with a tapered portion 31b, and the upper surface is chamfered on one side so that the tapered portion 31c gradually becomes thinner toward the end. Are formed.
In addition, the uppermost and lowermost partition plates 29U and 29L extend to the outlet side of the jet nozzle 28, and the other partition plates 2U and 29L extend.
The length is longer than 9.

A first target 33 for stabilizing the switching of the flow direction of the fluid is provided in the downstream flow path 25 facing the outlet side of the jet nozzle 28. On both sides of the first target 33, the side walls 34a, 3
4b are provided symmetrically.

Further, a second target 35 is provided at a central portion located downstream of the first target 33, and a return wall 36 extending in the width direction of the downstream flow path 25 is provided further downstream. Is provided. Return passages 37a, 37b are formed outside the side walls 34a, 34b, and discharge passages 38a,
38b are provided.

Therefore, the fluid jetted into the downstream flow path 25 is subjected to, for example, the right side wall 34a by the Coanda effect.
Flows along the inside of the Most of the fluid flowing to the right side wall 34a goes to the discharge passage 38a, but part of it becomes return fluid and goes to the return passage 37a.

The fluid energy of the return fluid is applied to the jet fluid, and the jet fluid flows along the inside of the left side wall 34b, and a part of the fluid flowing to the left side wall 34b becomes the return fluid. The fluid energy of the return fluid is applied to the ejected fluid, and the ejected fluid returns to the right side wall 3 again.
It flows along the inside of 4a. That is, the configuration is such that the alternating pressure wave is generated by the vibration phenomenon of the fluid ejected from the ejection nozzle 28 into the downstream flow path 25.

Further, a flow velocity sensor 40 and a piezoelectric film sensor 41 are provided at the bottom of the flow path main body 19 corresponding to the jet nozzle 28. The flow rate sensor 40 includes a sensor main body 42 and a detection unit 43, and the sensor main body 42
Is fixed to the bottom of the flow path main body 19, and the detection unit 43 faces the ejection nozzle 28.

That is, the flow velocity sensor 40 is installed at a position where the flow velocity in the width direction is narrowed and the flow velocity becomes the fastest in order to measure a minute flow rate region. The piezoelectric film sensor 41 is for measuring a large flow rate region, and includes a sensor main body 44 and a pressure wave introducing portion 45. The sensor main body 44 is fixed to the bottom of the flow path main body 19, The wave introduction part 45 communicates with a pair of pressure wave introduction ports 46, 46 which open at the outlet side of the jet nozzle 28 at a position where an alternating pressure wave is generated by a vibration phenomenon.

Therefore, the alternating pressure wave generated by the vibration phenomenon of the fluid ejected from the ejection nozzle 28 into the downstream flow path 25, that is, the pressure change caused by the change in the flow direction of the jet flow from the ejection nozzle 28 is reduced by the pressure wave inlet. It is detected by the piezoelectric film sensor 41 via 46,46. The waveform signals from the flow velocity sensor 40 and the piezoelectric film sensor 41 calculate the fluid flow rate from the frequency, and are displayed on the flow rate display window.

In the above embodiment, the interval between the uppermost partition plate 29U and the upper surface of the ejection nozzle 28 and the lowermost partition plate 29L among the plurality of partition plates 29 are described.
The distance between the lower surface of the jet nozzle 28 and the partition plate 29
Although it was formed to be larger than the interval between them, the flow rate sensor 40
And lowermost partition plate 29 of ejection nozzle 28 having
Even if only the distance between the partition plates 29 is larger than the distance between the partition plates 29, the sensitivity of the flow velocity sensor 40 can be increased, and the same effect can be obtained.

The fluid is dispersed by changing the shape of the tapered portions of the center partition plate and the upper and lower partition plates of the plurality of partition plates. Alternatively, the shape of the tapered portion may be a taper having the same vertical slope. Further, in the above embodiment, the tapered portion is formed by linear chamfering, but may be curved chamfering.

[0035]

As described above, according to the first aspect of the present invention, a plurality of partition plates are arranged at predetermined intervals inside the ejection nozzle, and at least one of these partition plates is provided. The distance between the lowermost partition plate and the lower surface of the ejection nozzle is larger than the distance between the partition plates. Therefore, there is an effect that the measurement sensitivity of the flow velocity sensor can be improved and accurate measurement can be performed even in a minute flow rate range.

According to the second and third aspects, one end of the partition plate located on the inlet side of the ejection nozzle and the other end of the partition plate located on the exit side of the ejection nozzle are gradually thinned toward the end. The tapered portion at one end of the partition plate is a taper inclined toward the center of the ejection nozzle, and the tapered portion at the other end of the partition plate is inclined upward and downward of the ejection nozzle. It is characterized by having a tapered shape. Therefore, the fluid flows along the taper and is stabilized, and the performance can be further improved.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing a jet nozzle of a fluid flow meter according to an embodiment of the present invention.

FIG. 2 is a vertical side view of the ejection nozzle of the embodiment.

FIG. 3 is a front view showing the internal structure of the fluidic flow meter of the embodiment.

FIG. 4 is a partially cutaway side view of the fluidic flow meter of the embodiment.

[Explanation of symbols]

17: Fluidic element, 19: Channel body, 22: Channel, 23: Partition wall, 24: Upstream channel, 25: Downstream channel, 28: Nozzle, 29: Partition plate, 30a-30
c: tapered portion, 31a to 31c: tapered portion.

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Naoshi Isshiki 2-3-2 Shimura, Itabashi-ku, Tokyo Inside Kinmon Manufacturing Co., Ltd. (56) References JP-A-4-175612 (JP, A) −58118 (JP, U)

Claims (4)

(57) [Claims] 1. An upstream flow path and a downstream flow path are defined by providing a partition in a flow path main body constituting a flow path, and ejection of fluid from the upstream flow path to the downstream flow path is performed on the partition. A nozzle is provided,
In a fluid flow meter provided with a flow velocity sensor on the lower surface of the ejection nozzle and a fluidic element in the downstream flow path, a plurality of partition plates are provided inside the ejection nozzle in parallel with the bottom surface of the flow path main body, In addition, they are arranged at a predetermined interval, and at least the interval between the lowermost partition plate and the lower surface of the ejection nozzle is larger than the interval between the partition plates. Fluidic flow meter. 2. A taper portion which gradually becomes thinner toward one end is formed at one end of a partition plate located on the inlet side of the ejection nozzle and the other end of the partition plate located on the exit side of the ejection nozzle. The fluidic flow meter according to claim 1, wherein: 3. A taper portion at one end of the partition plate is a taper that is concentrated and inclined toward a center portion of the ejection nozzle toward the end, and disperses a fluid passing through the ejection nozzle up and down the ejection nozzle. 3. The screen according to claim 1, wherein the tapered portion at the other end of the nozzle has a taper which is inclined upward and downward at the upper end and lower end of the ejection nozzle to disperse the fluid ejected from the ejection nozzle up and down. Dick flow meter. 4. The fluid flow meter according to claim 1, wherein the tapered portion of the partition plate is a straight or curved taper formed by chamfering.