JPH04158216A - Fluidic flowmeter - Google Patents

Abstract

PURPOSE:To make the performance of the title device stable by molding a body separate from the main body of a flow channel, by combining them removably, and by replacing only part of it when it turns faulty. CONSTITUTION:The main body 23 of a flow channel is molded by die casting, while a fluidic element 17 is molded of a synthetic resin material and incorporated in the main body 23. A fluid flowing in from a gas flow inlet body passes through the upstream-side channel 28 of the flow channel 26 and is straightened, and thereafter it flows toward a jet nozzle 32 with an increased flow velocity and is jetted into a downstream-side channel 29. When the fluid passes through the nozzle 32, a flow sensor 40 detects the flow velocity thereof. By a Coanda effect, moreover, the jetted fluid flows along the inside of a side wall 34a on the right side, for instance, and most of it runs toward a discharge passage 38a, while part of it runs as a returning fluid toward a return passage 37a. The fluid energy of this returning fluid is given to the jetted fluid and now it turns to flow along the inside of a side wall 34b on the left side. In other words, an alternating pressure wave is generated by the phenomenon of vibration of the fluid jetted into the channel 29 from the nozzle 32, and this wave is detected by a piezoelectric membrane sensor 41.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) This invention detects alternating pressure waves caused by vibration phenomena of fluid such as gas ejected from an ejection nozzle into a flow path, and determines the flow rate. Regarding fluidic flowmeters that detect

(Prior Art) Fluidic flowmeters installed in general households and the like to measure the flow rate of gas are known from, for example, Japanese Patent Application Laid-Open Nos. 63-313018 and 1-250725.

In this fluidic flowmeter, a fluidic element is provided in a flow channel body that forms a flow channel. This element is
It has an ejection nozzle that ejects fluid into a flow path, and a target is provided in the flow path facing the ejection nozzle. Furthermore, side walls are symmetrically provided on both sides of the target, and the flow rate is detected by detecting alternating pressure waves generated by the vibration phenomenon of the fluid ejected from the ejection nozzle using a piezoelectric film sensor.

That is, when the fluidic element ejects fluid from the ejection nozzle into the channel, the ejected fluid flows, for example, along the right side wall due to the Coanda effect.

A part of the fluid flowing to this right side wall becomes return fluid,
The fluid energy of this return fluid is imparted to the ejected fluid, causing the ejected fluid to flow along the left side wall, and a part of the fluid that has flowed to the left side wall becomes the return fluid, and the fluid energy of this return fluid is is applied to the ejected fluid, causing the ejected fluid to flow along the right side wall again. That is, alternating pressure waves are generated by the vibration phenomenon of the fluid ejected from the ejection nozzle into the flow path. This alternating pressure wave is detected by a piezoelectric film sensor, and the flow rate is calculated from this frequency to detect the flow rate of the fluid.

Therefore, the fluidic element, which is the flow rate measurement part of a fluidic flowmeter, has the problem that even slight changes in shape or irregularities cause turbulence in the fluid flow, making it impossible to measure accurately. is required.

(Problems to be Solved by the Invention) By the way, a flow channel body and a fluidic element forming a flow channel of a conventional fluidic flowmeter are integrally molded by die-casting. When integrally molded in this way, variations in dimensional accuracy occur, resulting in poor performance stability, a high incidence of defective products, and poor yield.

In particular, the constituent members of the fluidic element, such as the target and side walls, are long and narrow and protrude high from the bottom of the channel body. Moreover, in terms of performance, only a small taper can be applied to the target, side walls, etc., so there is a problem in that the molding die in those areas is worn out significantly, making it impossible to obtain a large number of molding shots.

Moreover, the flow channel body and the fluidic element are integrally molded by die-casting, and if the resulting molded product has dimensional defects, the entire product must be discarded, and the flowmeter must be disposed of after being assembled. Even if there is an instrumental difference as a result of test measurements, it is difficult to adjust the instrumental difference because the whole is one piece.

This invention was made in view of the above-mentioned circumstances, and its purpose is to achieve high dimensional accuracy, stabilize performance, and eliminate defects caused by fluidic elements. The aim is to make it possible to obtain a fluidic flowmeter with stable performance simply by replacing parts.

[Structure of the Invention] (Means and Effects for Solving the Problems) In order to achieve the above-mentioned object, the present invention has a jet nozzle that jets fluid into a flow path. A target is provided in the flow path facing the ejection nozzle, and side walls are symmetrically provided on both sides of the target, and alternating pressure waves generated by the vibration phenomenon of the fluid ejected from the ejection nozzle are detected by a piezoelectric film sensor. A fluidic device equipped with a fluidic element that detects the flow rate
In the FI meter, the flow channel main body and the fluidic element constituting the flow channel are molded separately, and the fluidic element is configured to be detachable from the flow channel main body.

By molding the channel body and the fluidic element in separate processes and removably combining them, they can be replaced if a dimensional defect or the like occurs in one of them.

According to a second aspect of the present invention, the jet nozzle is molded integrally with the flow channel main body, and the other fluidic element constituent members other than the jet nozzle are molded separately from the flow channel main body.

(Example) Hereinafter, one embodiment of the present invention will be described based on the drawings.

1 to 3 show the entire fluidic flowmeter, and 11 is a case. This case 11 is composed of a rectangular box-shaped case body 12 and a lid 13 that closes an opening of this case body 12. Case body 12
A gas inlet body 14 and a gas outlet body 15 are arranged side by side at the bottom, and a display window (not shown) is provided at the top. A fluidic element 17 and a cutoff valve 18, which will be described later, are installed in the lower part of the inside of the case 11.

That is, 23 is a channel main body formed by die casting or the like, and a channel 26 is formed by closing the opening of the channel main body 23 with a lid 25 via a backing 24.

This flow path 26 is divided by a partition wall 27, an upstream flow path 28 communicates with the gas inlet body 14, and a downstream flow path 29.
is in communication with the gas outlet body 15. Upstream flow path 2
A valve seat 30 is provided in the middle of the valve 8, and the valve body 31 of the cutoff valve 18 faces this valve seat 30. That is, when the pressure switch and the seismic sensor (not shown) detect an abnormality, the flow path 26 can be shut off by the shutoff valve 18.

A recessed portion 29a is provided at the bottom of the flow path main body 23 located in the downstream flow path 29, and this recessed portion 29a is connected to the partition wall 27.
It extends to a part of the upstream flow path 28 by penetrating through it. Therefore, the partition wall 27 is provided with a notch 27a having the same width as the extension of the concave portion 29a.

A fluidic element 17, which is separate from the channel body 23, is removably attached to the concave portion 29a and the cutout portion 27a. The fluidic element 17 is integrally molded from, for example, a synthetic resin material, and its base portion 19 is formed in the same shape as the recessed portion 29a. This base portion 19 is integrally provided with a projecting wall 20 that is fitted into the notch portion 27a, and this projecting wall 20 is provided with an ejection nozzle 32. This jet nozzle 32 has a slit shape that opens over the entire depth direction of the flow channel main body 23, and has protrusions 32a that project into the upstream flow channel 28 on both sides of the opening in the longitudinal direction.

32b, extending the nozzle passage length.

A first target 33 is provided at the base 19 located in the downstream flow path 29 facing the jet nozzle 32 for stabilizing switching of the flow direction of the fluid. This first
There are side walls 34a, 34 on both sides of the target 33.
b are provided symmetrically. Furthermore, a second target 35 is provided in the center located on the downstream side of the first target 33, and a downstream channel 2 is provided further downstream.
A return wall 36 extending in the width direction of the housing 9 is provided. A return flow path 3 is provided outside the side walls 34a and 34b.
7a, 37b are formed, and discharge passages 38a, 38b are provided outside both ends of the return wall 36.

By fitting the base 19 constituting the fluidic element 17 into the concave portion 29a of the channel main body 23 in this manner and attaching the lid body 25 to the channel main body 23 via the backing 24, the fluid The dick element 17 is the channel body 2
3, and by removing the lid 25, the fluidic element 17 can be extracted from the opening of the channel body 23.

Therefore, when fluid is ejected from the ejection nozzle 32 toward the downstream channel 29, the ejected fluid flows, for example, along the inside of the right side wall 34a due to the Coanda effect. Most of the fluid flowing into the right side wall 34a heads toward the discharge passage 38a, but a portion becomes return fluid and heads toward the return passage 37a. The fluid energy of this return fluid is imparted to the ejected fluid, and the ejected fluid begins to flow along the inside of the left side wall 34b. This time, a part of the fluid that has flowed to the left side wall 34b becomes the return fluid, and this return fluid flows along the inside of the left side wall 34b. The fluid energy of the fluid is imparted to the ejected fluid, causing the ejected fluid to flow again along the inside of the right side wall 34a. In other words,
It is configured so that alternating pressure waves are generated by the vibration phenomenon of the fluid ejected from the ejection nozzle 32 into the downstream flow path 29 .

Furthermore, the flow path main body 2 corresponding to the jet nozzle 32
3 has a flow sensor 4o and a piezoelectric film sensor 41 at the bottom.
is provided. The flow sensor 40 includes a sensor body 4
2 and a sensor chip 43 equipped with a detection part consisting of a heat generating part and a temperature sensing part, the sensor main body 42 is fixed to the bottom of the channel main body 23, and the sensor chip 43 faces the jet nozzle 32. . That is, the flow sensor 40 is
In order to measure a small flow rate region, the flow path is narrowed and installed at a position where the flow velocity is the highest. Further, the piezoelectric film sensor 41 is for measuring a large flow rate range, and is composed of a sensor body 44 and a pressure wave introducing section 45.

On the other hand, in the upstream flow path 28, there is a flat first rectifying plate 47 made of a wire mesh and a mountain-shaped second rectifying plate 4 made of a wire mesh.
8 are installed, and these are provided so that they can be attached to and detached from the channel body 23.

Next, the operation of the fluidic flowmeter configured as described above will be explained. The fluid flowing in from the gas inlet body 14 passes through the upstream flow path 28 of the flow path 26, and further passes through the first flow path 28.
After being rectified by the rectifier plate 47 and the second rectifier plate 48, it heads toward the jet nozzle 32. Since the flow path of the jet nozzle 32 is narrowed, the flow velocity of the fluid increases, and the fluid is jetted from the jet nozzle 32 to the downstream flow path 29 . As the fluid passes through the jet nozzle 32, its flow rate is detected by a flow sensor 40. When fluid is ejected from the ejection nozzle 32 toward the downstream channel 29, the ejected fluid flows, for example, along the inside of the right side wall 34a due to the Coanda effect. Most of the fluid flowing into the right side wall 34a heads toward the discharge passage 38a, but a portion becomes return fluid and heads toward the return passage 37a. The fluid energy of this return fluid is imparted to the ejected fluid, and the ejected fluid is transferred to the left side wall 34.
A part of the fluid that has flowed to the left side wall 34b becomes a return fluid, and the fluid energy of this return fluid is given to the ejected fluid, and the ejected fluid returns to the right side wall 34a. It starts to flow along the inside of the . That is, an alternating pressure wave is generated by the vibration phenomenon of the fluid ejected from the ejection nozzle 32 into the downstream flow path 29 .

This alternating pressure wave, that is, a pressure change caused by a change in the flow direction of the jet from the jet nozzle 32 is detected by the piezoelectric film sensor 41.

The fluid flow rate is calculated from the frequency of the waveform signals from the flow sensor 40 and the piezoelectric film sensor 41 and displayed on the display window.

In addition, when assembling the fluidic flowmeter, the channel body 23 is molded by die casting, the fluidic element 17 is molded from a synthetic resin material, and the channel body 23 is molded by die-casting.
It can be assembled by a simple operation of incorporating the fluidic element 17 into the structure. In other words, the fluidic element 17, which is a flow rate measurement unit, has the problem that even slight changes in shape or irregularities cause turbulence in the flow of the fluid, making it impossible to measure accurately. Therefore, fairly high dimensional accuracy is required. , can be manufactured with high precision by manufacturing in a separate process from the channel body 23.

Moreover, if a defect occurs due to the fluidic element 17 after assembly, or if an instrumental error occurs, the fluidic element 17 can be replaced, and the replacement work can also be done with the lid body.
It can be easily attached and detached by removing 5.

Note that in the above embodiment, the fluidic element 1
The present invention is not limited to the above-mentioned embodiment, and as shown in FIG.
2, and the other fluidic element components except the ejection nozzle 32, that is, the first target 33 and the side wall 34a.
.

34b1 The second target 35 and return wall 36 may be integrally provided on the base 19.

Further, in the embodiment described above, the channel main body 23 was molded by die-casting and the fluidic element 17 was molded from synthetic resin, but both may be molded separately by die-casting, and the fluidic element 17 It may also be formed by machining metal.

[Effects of the Invention] As explained above, according to the present invention, the flow channel main body and the fluidic element constituting the flow channel are molded separately, and the fluidic element can be attached to and detached from the flow channel main body. Since the flow path body and the fluidic element are molded in separate processes and removably combined, performance is stable because even if a defective product occurs due to the fluidic element, only part of it can be replaced. It is possible to obtain a fluidic flow meter with a high quality and minimize the cost of replacement. Moreover, the fluidic element, which is the flow rate measuring section, can be manufactured with high dimensional accuracy, and the performance can be stabilized.

[Brief explanation of drawings]

Figures 1 to 3 show an embodiment of the present invention, in which Figure 1 is a longitudinal sectional front view of the flow passage main body and fluidic element of a fluidic flowmeter, Figure 2 is a longitudinal sectional side view of the same, and FIG. 3 is a longitudinal sectional front view of a fluidic flowmeter, and FIG. 4 is a longitudinal sectional front view of a flow channel body and a fluidic element showing another embodiment of the present invention. DESCRIPTION OF SYMBOLS 11... Case, 23... Channel body, 26... Channel, 32... Spray nozzle, 33... Target, 4
1... Piezoelectric film sensor, 43a, 43b... Side wall. Applicant's agent Patent attorney Takehiko Suzue Figure 1 Figure 2 9a Figure 3

Claims (2)

[Claims] (1) It has an ejection nozzle that ejects fluid into a flow path, and a target is provided in the flow path opposite to this ejection nozzle, and side walls are provided symmetrically on both sides with the target in between, and from the ejection nozzle. In a fluidic flowmeter equipped with a fluidic element that detects the flow rate by detecting alternating pressure waves caused by the vibration phenomenon of the ejected fluid using a piezoelectric film sensor, a flow passage main body constituting the flow passage and the fluidic element are connected to each other. A fluidic flowmeter characterized in that a fluidic element is formed separately and configured to be detachable from a flow channel body. (2) It has an ejection nozzle that ejects fluid into a flow path, a target is provided in the flow path facing the ejection nozzle, and side walls are provided symmetrically on both sides with the target in between, so that the ejection nozzle In a fluidic flowmeter equipped with a fluidic element that detects the flow rate by detecting alternating pressure waves caused by the vibration phenomenon of the ejected fluid using a piezoelectric film sensor, the ejection nozzle is molded integrally with the flow channel main body, A fluidic flowmeter characterized in that the fluidic element components other than the jet nozzle are molded separately from the flow channel main body, and the fluidic element is configured to be detachable from the flow channel main body.