JPH06241843A - Fluidic flowmeter - Google Patents

Abstract

PURPOSE:To form a pressure-signal transfer passage by a simple structure, to reduce the number of components and to enhance a working property by a method wherein pressure-wave introduction parts are formed in two parts in which alternating pressure waves are generated at the bottom part of a flow-passage body or at the bottom part of a fluidic element. CONSTITUTION:One pair of recessed grooves 57 as pressure-wave introduction parts are formed symmetrically in positions in which alternating pressure waves are generated by a vibrating phenomenon at the bottom part 50 near the exist of a jet nozzle 32. The recessed grooves 57 are opened to a flow passage 26. Ends, on one side, of recessed stripe grooves 58 as pressure-signal transfer passages formed in a recessed and dented part 29a in a flow-passage body 23 are made to communicate with the recessed grooves 57, and ends on the other side are extended up to through holes 56. Openings in the recessed stripe grooves 58 are blocked by the bottom part 52 of a fluidic element 51 fitted to the recessed and dented part 29a, and the recessed stripe grooves 58 are formed in a cave along the bottom face of the recessed and dented part 29a. Thereby, a flow sensor 40 and a piezoelectric film sensor 41 can be installed side by side on the same side face of the flow-passage body 23.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluidic flow meter which detects an alternating pressure wave generated by an oscillating phenomenon of a fluid such as a gas ejected from an ejection nozzle into a flow passage to detect a flow rate.

[0002]

2. Description of the Related Art A fluidic flow meter for measuring the flow rate of gas, which is installed in a general household or the like, is disclosed in, for example, Japanese Patent Laid-Open No. 63-63.
It is known from JP-A-313018 and JP-A-1-250725.

The fluidic flowmeter has a jet nozzle provided on the inlet side of the flow passage. When a fluid is jetted from this jet nozzle into the flow passage, the jetted fluid flows along the side wall on the right side, for example, due to the Coanda effect. A part of the fluid that has flowed to the right side wall becomes the return fluid, the fluid energy of this return fluid is imparted to the ejected fluid, and the ejected fluid flows along the left side wall, which in turn flows to the left side wall. A part of the discharged fluid becomes a return fluid, the fluid energy of the return fluid is applied to the jet fluid, and the jet fluid again flows 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. This alternating pressure wave is detected by the piezoelectric film sensor, the flow rate is calculated from this frequency, and the flow rate of the fluid is detected.

By the way, in order to detect the alternating pressure wave, it is necessary to provide a pressure wave introducing portion near the outlet of the jet nozzle at a position where the alternating pressure wave is generated, but other constituent members are provided near the outlet of the jet nozzle. It is necessary to install the piezoelectric film sensor at a position away from the vicinity of the outlet of the ejection nozzle,
The pressure wave introducing portion and the piezoelectric film sensor are transmitted via the pressure signal transmission path.

That is, FIGS. 3 to 6 show pressure signal transmission paths in the conventional fluidic flowmeter. 3 and 4 show the entire fluidic flow meter, and 11 is a case. The case 11 is a rectangular box-shaped case body 12
And a lid 13 that closes the opening of the case body 12.

At the lower part of the case body 12, the gas inlet body 1 is provided.
4 and the gas outlet body 15 are arranged side by side, and a display window 16 is provided on the upper part.
Is provided. A fluidic element 17 and a shutoff valve 18, which will be described later, are installed in the lower part inside the case 11, and a battery 19, a pressure switch 20, a vibration sensor 21, and an integrated display substrate 22 facing the display window 16 are provided in the upper part.
Is installed.

The fluidic element 17 will be described. Reference numeral 23 is a flow path body formed by die casting or the like. The opening of the flow path body 23 is packed 2
The flow path 26 is formed by closing the cover body 4 with the lid 25.

The flow passage 26 is divided by a partition wall 27, and the upstream flow passage 28 communicates with the gas inlet body 14.
The downstream flow path 29 communicates with the gas outlet body 15. A valve seat 30 is provided in the upstream flow passage 28, and the valve body 31 of the shutoff valve 18 faces the valve seat 30. That is, when the pressure switch 20 and the vibration sensor 21 detect an abnormality, the shutoff valve 18 can shut off the flow path 26.

A jet nozzle 32 is provided on the partition wall 27 of the flow path body 23, as shown in FIG. The jet nozzle 32 has a slit shape that opens over the entire depth direction of the flow path main body 23, and has protrusions 32a and 32b that project to the upstream flow path 28 on both side edges of the opening in the longitudinal direction.
The nozzle passage length is extended.

A first target 33 for stabilizing the flow direction switching of the fluid is provided in the downstream flow path 29 facing the jet nozzle 32. Side walls 34a and 34b are symmetrically provided on both sides of the first target 33.

Further, a second target 35 is provided in a central portion located on the downstream side of the first target 33, and a return wall 36 extending in the width direction of the downstream side flow passage 29 is further provided on the downstream side. It is provided. Return passages 37a and 37b are formed outside the side walls 34a and 34b, and discharge passages 38a and 37a are formed outside both ends of the return wall 36.
38b is provided.

Therefore, when the fluid is jetted from the jet nozzle 32 toward the downstream flow passage 29, the jet fluid flows along the inside of the right side wall 34a by the Coanda effect, for example.

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 is supplied to the left side wall 34.
The fluid flows along the inner side of b, and a part of the fluid that has flowed to the left side wall 34b this time becomes the return fluid, the fluid energy of this return fluid is applied to the jet fluid, and the jet fluid is again supplied to the right side wall 34a. It will flow along the inside of. That is, the alternating pressure wave is generated by the vibration phenomenon of the fluid ejected from the ejection nozzle 32 into the downstream side flow passage 29.

Further, a flow sensor 40 and a piezoelectric film sensor 41 are provided on the side surface of the flow path body 23 corresponding to the jet nozzle 32. The flow sensor 40 is
The sensor body 42 includes a sensor body 43 and a sensor chip 43 having a detection portion including a heat generating portion and a temperature sensing portion.
Is fixed to the side surface of the flow path body 23, and the sensor chip 43
Facing the ejection nozzle 32.

That is, the flow sensor 40 is installed at a position where the flow velocity is the highest because the flow passage is narrowed in order to measure the minute flow rate region. Further, the piezoelectric film sensor 41 is for measuring a large flow rate region, and comprises a sensor body 44 and a pressure wave introducing portion 45, as shown in FIG. Of the pressure wave introducing portion 45 near the outlet of the jet nozzle 32.
It is installed at a position where an alternating pressure wave generated by the vibration phenomenon occurs.

That is, circular recesses 46, 46 as a pair of grooves are symmetrically provided on the inner wall of the flow path body 23 located near the outlet of the jet nozzle 32. Further, as shown in FIG. 5, a concave groove 47, which communicates with the concave portions 46, 46 and extends to the outlet side corner portion of the jet nozzle 32,
47 is engraved on the inner wall of the flow path body 23.

Further, a through hole 48 penetrating the side surface of the flow path main body 23 is formed at the bottom of the recessed portions 46, 46 at a position deviated in the direction opposite to the recessed groove 47, and the sensor main body 4 is provided.
It communicates with 4.

On the other hand, the concave groove 47 is formed in the concave portions 46, 46.
Caps 49, 49 each having a notch portion are fitted in a portion corresponding to. Moreover, the bottom surfaces of the caps 49, 49 are located on the same plane as the bottom surface of the flow path body 23 so that the flow path 26 is not uneven.

With this structure, the pressure wave introducing port 47a is formed in the downstream side flow passage 29 of the flow passage main body 23 and at the outlet side corner of the jet nozzle 32, and the pressure wave introducing port 47a is concave. The sensor body 44 is inserted through the groove 47, the recess 46 covered with the cap 49, and the through hole 48.
And a pressure signal transmission path 50 is formed.

That is, the pressure signal transmission path 50 forms a bypass path for the pressure signal, and the sensor body 44 of the piezoelectric film sensor 41 is replaced by the sensor body 42 of the flow sensor 40.
The flow sensor 40 and the piezoelectric film sensor 41 can be arranged side by side on the same side surface of the flow path body 23 while avoiding the overlap.

Therefore, the fluid flowing from the gas inlet body 14 passes through the upstream flow passage 28 of the flow passage 26, and is further rectified by the first rectifying plate 51 and the second rectifying plate 52, and then the ejection nozzle. Head to 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 side flow passage 29. When the fluid passes through the ejection nozzle 32, the flow velocity of the fluid is detected by the flow sensor 40.

When the fluid is jetted from the jet nozzle 32 toward the downstream flow passage 29, the jet fluid flows, for example, along the inside of the right side wall 34a by the Coanda effect.
Most of the fluid that has flowed to the right side wall 34a is directed to the discharge passage 38a, but part of the fluid becomes return fluid, and the return passage 3
Go to 7a.

The fluid energy of the return fluid is applied to the jetted fluid so that the jetted fluid flows along the inside of the left side wall 34b, and a part of the fluid that has flowed to the left side wall 34b becomes the return fluid this time. , The fluid energy of the return fluid is applied to the jetted fluid, and the jetted fluid is again fed to the right side wall 3
It comes to flow along the inside of 4a.

That is, from the jet nozzle 32 to the downstream side flow path 2
An alternating pressure wave is generated by the vibration phenomenon of the fluid jetted into the inside 9. This alternating pressure wave, that is, the pressure change caused by the change in the flow direction of the jet flow from the jet nozzle 32 is detected by the piezoelectric film sensor 41 via the pressure signal transmission paths 50, 50.

[0027]

However, as described above, as a means for transmitting the pressure wave introducing portion and the piezoelectric film sensor, the concave portion 46 is provided at the bottom of the flow path body 23, and the concave portion 46 is capped. It is closed by 49 and is transmitted via the pressure signal transmission path 50. Further, the bottom surface of the cap 49 needs to be formed on the same plane as the bottom surface of the flow path body 23 so that the flow path 26 is not uneven, and dimensional accuracy is required. Therefore, the number of parts is increased and the assembling work is troublesome, which causes a cost increase.

The present invention has been made by paying attention to the above circumstances, and an object thereof is to form a pressure signal transmission path for transmitting a pressure wave with a simple structure, thereby reducing the number of parts. An object of the present invention is to provide a fluidic flow meter capable of improving the assembling workability.

[0029]

According to the present invention, in order to achieve the above-mentioned object, a flow path main body forming a flow path and a fluidic element incorporated in the flow path main body are separately formed. At the same time, a piezoelectric film sensor that has a jet nozzle for jetting a fluid in the flow passage and detects a flow rate by detecting an alternating pressure wave generated by a vibration phenomenon of the fluid jetted in the flow passage from the jet nozzle is used. In the fluidic flowmeter provided outside the channel case, pressure wave introducing portions are provided at two places where an alternating pressure wave is generated at the bottom of the flow passage body or the bottom of the fluidic element, and at the bottom of the flow passage body, A through hole that communicates with the piezoelectric film sensor is provided, and a pressure signal transmission path that communicates between the pressure wave introducing portion and the through hole is formed between the bottom of the flow path body and the bottom of the fluidic element. .

An alternating pressure wave generated by the vibration phenomenon of the fluid when the fluid is ejected from the ejection nozzle is transmitted from the pressure wave introducing portion to the piezoelectric film sensor through the pressure signal transmission path and the through hole, and the piezoelectric film sensor. The flow rate is measured by.

[0031]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings.

FIGS. 1 and 2 show the essential parts of the fluidic flow meter. A recessed portion 29a is provided in the bottom portion 50 located in the downstream side flow passage 29 of the flow passage body 23 formed by die casting or the like. Has been. Then, the concave portion 2
A fluidic element 51, which is separate from the flow path body 23, is detachably attached to 9a. The fluidic element 51 is integrally formed of, for example, a synthetic resin material, and its bottom portion 52 is formed in the same shape as the concave portion 29a.

A jet nozzle 32 provided in the flow path body 23
A first target 33 for stabilizing the flow direction switching of the fluid is provided on the bottom portion 52 located in the downstream side flow passage 29 opposite to, similarly to the conventional case.

Side walls 34a and 34b are symmetrically provided on both sides of the first target 33. Further, a second target 35 is provided in a central portion located on the downstream side of the first target 33, and a return wall 3 extending in the width direction of the downstream side flow passage 29 is provided on the downstream side.
6 is provided. Then, the side walls 34a, 34b
Return passages 37a and 37b are formed on the outside of the return wall 36, and discharge passages 38a and 38b are provided on the outside of both ends of the return wall 36.

In this way, the concave portion 29a of the flow path case 23 is formed.
The bottom portion 52 of the fluidic element 51 is fitted to the fluidic element 5 and the lid 25 is attached to the flow path body 23 via the packing 24.
1 is fixed to the channel body 23, and the fluidic element 51 can be pulled out from the opening of the channel body 23 by removing the lid 25.

Further, a flow sensor 40 and a piezoelectric film sensor 41 are provided on the outer surface of the bottom portion 50 of the flow path body 23. The piezoelectric film sensor 41 is for measuring a large flow rate range, and includes a pressure wave detection unit 44a on the sensor body 44.
Is provided, and the periphery of the pressure wave detecting portion 44a is sealed by a packing 55 interposed between the pressure wave detecting portion 44a and the bottom portion 50 of the flow path body 23. The bottom portion 50 of the flow path body 23 facing the pressure wave detecting portion 44a is provided with a through hole 56 penetrating to the concave portion 29a.

On the other hand, in the bottom portion 50 located in the vicinity of the outlet of the jet nozzle 32, a pair of concave grooves 57 as pressure wave introducing portions are symmetrically provided at a position where an alternating pressure wave is generated due to a vibration phenomenon. 57 is open to the flow path 26.

Further, one end side of a groove groove 58 as a pressure signal transmission path provided in the recessed portion 29a of the flow path body 23 communicates with this groove 57, and the other end side extends to the through hole 56. is doing. Further, the opening of the groove 58 is the bottom 52 of the fluidic element 51 fitted in the recess 29a.
The concave groove 58 is formed as a lateral hole along the bottom surface of the concave portion 29a.

With this structure, a concave groove 57 is formed in the downstream side flow passage 29 of the flow passage main body 23 and as a pressure wave introducing portion that opens to the outlet side corner of the jet nozzle 32. The groove 57 has a pressure signal path communicating with the sensor body 44 via the groove 58 and the through hole 56 covered by the bottom portion 52 of the fluidic element 51.

That is, this pressure signal path forms a bypass path for the pressure signal, avoids that the sensor body 44 of the piezoelectric film sensor 41 overlaps with the sensor body 42 of the flow sensor 40, and avoids the same flow path body 23. The flow sensor 40 and the piezoelectric film sensor 41 can be arranged side by side.

Therefore, the fluid flowing in from the gas inlet body 14 passes through the upstream side flow passage 28 of the flow passage 26 toward the ejection nozzle 32. Since the flow path of the ejection nozzle 32 is narrowed, the flow velocity of the fluid is increased, and the fluid is ejected from the ejection nozzle 32 to the downstream flow passage 29. Fluid is ejected from nozzle 32
When passing through, the flow velocity is detected by the flow sensor 40.

When the fluid is jetted from the jet nozzle 32 toward the downstream passage 29, the jet fluid flows along the inside of the right side wall 34a by the Coanda effect, for example.
Most of the fluid that has flowed to the right side wall 34a is directed to the discharge passage 38a, but part of the fluid becomes return fluid, and the return passage 3
Go to 7a.

The fluid energy of this return fluid is applied to the jetted fluid so that the jetted fluid flows along the inside of the left side wall 34b, and a part of the fluid that has flowed to the left side wall 34b becomes the return fluid this time. , The fluid energy of the return fluid is applied to the jetted fluid, and the jetted fluid is again fed to the right side wall 3
It comes to flow along the inside of 4a.

That is, from the jet nozzle 32 to the downstream side flow path 2
An alternating pressure wave is generated by the vibration phenomenon of the fluid jetted into the inside 9. This alternating pressure wave, that is, the pressure change caused by the change in the flow direction of the jet flow from the jet nozzle 32 is detected by the piezoelectric film sensor 41 via the pressure signal path.

It should be noted that, in the above-described embodiment, the concave groove 58 as the pressure signal transmission path is formed in the concave portion 29 of the flow path body 23.
The groove 58 is formed by covering the groove 58 of the fluidic element 51 with the bottom 52 of the fluidic element 51. However, the groove 52 is formed in the bottom 52 of the fluidic element 51, and the groove 52 of the channel body 23 is formed. It may be formed so as to be covered with the concave portion 29a, or a pressure signal transmission path may be formed by providing concave groove grooves facing each other in both the concave portion 29a of the flow path body 23 and the bottom portion 52 of the fluidic element 51. Good.

Although the jet nozzle 32 is provided in the partition wall 27 of the flow passage body 23 in the above-described embodiment, the jet nozzle 32 may be integrally provided in the fluidic element 51 and incorporated in the flow passage body 23.

[0047]

As described above, according to the present invention, pressure wave introducing portions are provided at two places where alternating pressure waves are generated at the bottom of the flow passage body or the bottom of the fluidic element, and the flow passage main body is provided. Since a through hole that communicates with the piezoelectric film sensor is provided at the bottom, and a pressure signal transmission path that connects the pressure wave introducing portion and the through hole is formed between the bottom of the flow path body and the bottom of the fluidic element, The pressure signal transmission path can be formed only by incorporating a fluidic element in the path body.

Therefore, unlike the conventional case, the troublesome work of providing the concave portion and closing the concave portion with the cap is unnecessary, the number of parts is reduced, the assembling workability can be improved, and the cost can be reduced. The effect is that you can do it.

[Brief description of drawings]

FIG. 1 is a vertical sectional front view of a main part of a fluidic flow meter according to an embodiment of the present invention.

FIG. 2 is a vertical cross-sectional side view of a main part of the fluidic flow meter of the embodiment.

FIG. 3 is a vertical sectional front view of a conventional fluidic flow meter.

FIG. 4 is a vertical sectional side view of a conventional fluidic flow meter.

FIG. 5 is a vertical sectional front view showing a part of a conventional fluidic flow meter.

FIG. 6 is a cross-sectional plan view showing a part of a conventional fluidic flow meter.

[Explanation of symbols]

23 ... Flow path main body, 26 ... Flow path, 32 ... Jet nozzle, 41
... Piezoelectric film sensor, 51 ... Fluidic element, 50, 5
2 ... bottom part, 56 ... through hole, 57 ... concave groove, 58 ... concave groove.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Naoshi Isshiki 1-3-2 Shimura, Itabashi-ku, Tokyo Inside Kinmon Manufacturing Co., Ltd.

Claims (3)

[Claims] 1. A flow path main body forming a flow path and a fluidic element incorporated in the flow path main body are separately configured, and an ejection nozzle for ejecting a fluid is provided in the flow path. In a fluidic flowmeter provided with a piezoelectric film sensor for detecting a flow rate by detecting an alternating pressure wave generated by a vibration phenomenon of a fluid ejected from an ejection nozzle into a flow channel, At the bottom or at the bottom of the fluidic element, pressure wave introducing portions are provided at two locations where alternating pressure waves are generated, and a through hole communicating with the piezoelectric film sensor is provided at the bottom of the flow passage body, and the bottom portion of the flow passage body is provided. And a bottom portion of the fluidic element, wherein a pressure signal transmission path that connects the pressure wave introducing portion and the through hole is formed. 2. A flow path main body that constitutes a flow path and a fluidic element incorporated in the flow path main body are separately configured, and an ejection nozzle for ejecting a fluid to the fluidic element is provided. In a fluidic flowmeter provided with a piezoelectric film sensor for detecting a flow rate by detecting an alternating pressure wave generated by a vibration phenomenon of a fluid ejected from an ejection nozzle into a flow channel, At the bottom or at the bottom of the fluidic element, pressure wave introducing portions are provided at two locations where alternating pressure waves are generated, and a through hole communicating with the piezoelectric film sensor is provided at the bottom of the flow passage body, and the bottom portion of the flow passage body is provided. And a bottom portion of the fluidic element, wherein a pressure signal transmission path that connects the pressure wave introducing portion and the through hole is formed. 3. The fluidic flowmeter according to claim 1, wherein the pressure signal transmission path is a groove formed in the bottom of the flow path body or the bottom of the fluidic element.