JP2545273Y2 - 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 a 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.

In a fluidic flow meter, an ejection nozzle is provided on the inlet side of a flow path. When a fluid is ejected from the ejection nozzle into the flow path, 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.

Incidentally, this kind of general household gas flow meter is installed outdoors. Therefore, since they are exposed to the wind and rain and have a long service life of 10 years, it is necessary to manufacture them in a structure that can withstand them.

Therefore, in general, a case for housing various sensors including a fluidic element has a watertight structure made of a metal material. The flow path body in the case is provided with a shutoff valve that shuts off the flow path of the fluid. This shutoff valve is a signal from a seismic sensor that detects an earthquake or a gas leak alarm that detects a gas leak. And cut off the gas flow.

Accordingly, when the shut-off valve is operated to cut off the flow path and then to be returned, the switch provided on the case is operated to return the shut-off valve.
This switch also needs to be configured in a watertight structure for the reasons described above.

Therefore, conventionally, the upper part of the switch provided on the upper part of the case is covered with a resin sheet,
An operation rod sealed by an O-ring is provided in a part of the case, and a switch provided inside the case is operated by the operation rod.

[0010]

However, as described above, the watertight structure in which the upper part of the switch is covered with a resin sheet has no protrusion on the upper surface of the case and can improve the appearance and beauty of the switch. Because the stroke for pressing is small, when another member comes into contact with the resin sheet, the switch may operate or cause a malfunction.

If a concave structure is used to prevent this, rainwater accumulates in the concave portion, and when a load is repeatedly applied to the sheet, cracks are generated in the sheet, and the watertight structure is damaged. Further, the structure in which the operation rod is pivotally supported on the case in a water-tight manner has many parts, and is structurally complicated, has a large size, and has a drawback of impairing the aesthetic appearance.

The present invention has been made in view of the above circumstances, and its purpose is to prevent a switch from malfunctioning and to maintain a perfect watertight structure for a long period with a simple structure. It is small, has no protrusion,
An object of the present invention is to provide a fluidic flow meter with an improved appearance.

[0013]

In order to achieve the above object, according to the present invention, a switch is provided in a part of a case via a switch case, and the switch is watertightly connected to the switch case. Cover the watertight cover outside and inside
Double, and project from the case to the outer watertight cover
Provide a protruding part and remove the outer peripheral part of the outer watertight cover.
Engage with the engagement groove of the switch case, and
Between the watertight cover and the inner watertight cover and this inner
The first and the second between the watertight cover and the operation part of the switch.
, A protrusion amount of the protrusion is a, and a first gap
When the gap amount of the portion is b and the gap amount of the second gap portion is c
A <(b + c), and place other equipment on the case
Switch is not activated even if the protrusion is pressed
I did it.

When the switch is operated, if the watertight cover is pushed in deeply with a finger, the watertight cover is bent and the switch operation section is operated. Therefore, the switch does not operate carelessly.

[0015]

[0016]

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

FIG. 2 and FIG. 3 show the entire 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 lower part of the case body 12, a gas inlet 1 is provided.
4 and a gas outlet 15 are arranged side by side, and a display window 16
Is provided. A fluidic element 17 and a shutoff valve 18, which will be described later, are installed in the lower part of the case 11.
Is installed.

The fluidic element 17 will be described. Reference numeral 23 denotes a flow path main body formed by die casting or the like.
The flow path 26 is configured by being closed by the lid 25 through the cover 4.

The flow path 26 is defined by a partition wall 27, and the upstream flow path 28 communicates with the gas inlet 14.
The downstream flow passage 29 communicates with the gas outlet 15. A valve seat 30 is provided in the middle of the upstream flow path 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 seismic sensor 21 detect an abnormality, the flow path 26 can be shut off by the shutoff valve 18.

A jet nozzle 32 is provided on the partition wall 27 of the flow path main body 23. The ejection nozzle 32 has a slit shape that opens over the entire depth direction of the flow path main body 23, and has protrusions 32 a and 32 b that protrude into the upstream flow path 28 on both side edges in the longitudinal direction of the nozzle main body. The length has been extended.

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

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 29 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, when the fluid is ejected from the ejection nozzle 32 toward the downstream flow path 29, the ejected fluid flows, for example, along the inside of the right side wall 34a by the Coanda effect. 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 ejected fluid, and the ejected 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 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.

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

In other words, the flow sensor 40 is installed at a position where the flow path 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 section 45.
Is fixed to the side surface of the flow path main body 23, and the pressure wave introducing portion 45
Is installed in the vicinity of the outlet of the ejection nozzle 32 at an optimum extraction position of the alternating pressure wave generated by the vibration phenomenon.

Further, as shown in FIG.
A switch mounting hole 46 is drilled in a part of the upper surface of 1. This switch mounting hole 46 has a large diameter portion 46 at the top.
a, a lower portion 46b is provided at a lower portion, and a switch case 4 made of, for example, ABS is provided in the switch mounting hole 46.
7 are stored.

The switch case 47 is provided with the large diameter portion 46.
a small-diameter cylindrical portion 47b having a bottom that closely fits into a large-diameter cylindrical portion 47a and a small-diameter portion 46b, on which a switch 48 having an operation portion 48a at the top is fixed. Have been.

Further, the large-diameter cylindrical portion 47a has an opening edge portion 49, and an annular groove portion 50 is provided on the inner peripheral surface. The annular groove 50 is provided with double outer and inner watertight covers 51 and 52.

The outer watertight cover 51 is formed in a disk shape with a thick rubber, and a protrusion 51a protruding from the upper surface of the case 11 is provided on the upper surface thereof. further,
An engagement groove 53 that engages with the opening edge 49 of the switch case 47 is provided on the outer peripheral surface of the watertight cover 51.
Therefore, the watertight cover 51 closes the opening of the switch case 47 in a watertight manner.

Further, the inner watertight cover 52 is formed in a hat shape by thin rubber, and its outer peripheral edge is formed with an annular engaging groove 5 formed on the lower end surface of the outer watertight cover 51.
4 are provided with engaging projections 55.

Therefore, the switch 48 is connected to the watertight cover 5.
The outer watertight cover 51, which is doubly covered by 1 and 52,
A first gap 56 a is provided between the first watertight cover 52 and the inner watertight cover 52.
Is formed, and a second gap portion 56b is provided between the inner watertight cover 52 and the operation portion 48a of the switch 48.

The protrusion amount of the protrusion 51a is represented by a,
The gap amount of the first gap portion 56a is b, and the second gap portion 56b is
When the gap amount is c, a <(b + c) is formed. That is, even if another device or the like is placed on the upper surface of the case 11 and the protruding portion 51a is pressed, the operation portion 48 of the switch 48
a is not pushed in, and the operation stroke is configured to be large so that the operation unit 48a is not operated unless the watertight covers 51 and 52 are pushed in deeply by fingers.

Next, the operation of the fluidic flow meter configured as described above will be described. Gas inlet body 14
Flows through the upstream flow path 28 of the flow path 26 toward the ejection nozzle 32.

Since the flow path of the ejection nozzle 32 is narrowed, the flow velocity of the fluid increases, and the fluid is ejected from the ejection nozzle 32 to the downstream flow path 29. When the fluid passes through the ejection nozzle 32, its flow velocity is detected by the flow sensor 40. When the fluid is ejected from the ejection nozzle 32 toward the downstream flow path 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 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 ejected fluid, and the ejected fluid is supplied to the left side wall 34.
b, and a part of the fluid that has flowed to the left side wall 34b becomes return fluid, and the fluid energy of this return fluid is applied to the ejected fluid, and the ejected fluid returns to the right side wall 34a. Will flow along the inside of the.

That is, from the jet nozzle 32 to the downstream flow path 2
An alternating pressure wave is generated due to the vibration phenomenon of the fluid ejected into 9. The alternating pressure wave, that is, the pressure change caused by the change in the flow direction of the jet from the jet nozzle 32 is detected by the piezoelectric film sensor 41. The waveform signals from the flow sensor 40 and the piezoelectric film sensor 41 are used to calculate the fluid flow rate from the frequency and are displayed on the integration display board 22.

Further, a shut-off valve 18 is provided by a signal from a seismic sensor for detecting an earthquake or a gas leak alarm for detecting a gas leak.
Operates, the flow path 26 is instantaneously shut off, so that gas leakage can be prevented.

Further, after confirming the safety, the shut-off valve 18
When the watertight covers 51 and 52 are pressed deeply with fingers, the watertight covers 51 and 52 bend and the watertight cover 52 pushes down the operation unit 48a of the switch 48. Accordingly, the shut-off valve 18 can be returned to the open state to open the flow path 26, and the operation state is restored.

A first gap 56a is provided between the outer watertight cover 51 and the inner watertight cover 52, and a second gap 56b is provided between the outer watertight cover 52 and the operation section 48a.
Is provided, even if fingers or other members come into contact with the watertight covers 51, 52, the operation unit 48a is not operated unless the watertight covers 51, 52 are pushed deeply. Can be prevented.

[0042]

As described above, according to the first aspect of the present invention, a switch is provided on a part of a case via a switch case, and the switch case is provided with a watertight cover that covers the switch in a watertight manner on the outside and inside. Double installation, outer watertight
While providing a projecting part that protrudes from the case on the cover,
The outer periphery of the outer watertight cover is engaged with the switch case.
The outer watertight cover and the inner watertight cover engaging the groove.
Operation of the watertight cover and switch between and inside the bar
Providing first and second gaps between the working portion and the projecting portion;
The protrusion amount of the portion is a, the gap amount of the first gap portion is b,
When the gap amount of the gap is c, a <(b + c)
And features. Therefore, when the watertight cover pushed deeply by hand, since the operation portion of the switch is operated is bent watertight cover, since only pushed shallow have a gap, since the operation portion of the switch is not operated, inadvertently switch Does not operate, and malfunction of the switch can be prevented. Furthermore, a simple structure can maintain a perfect watertight structure for a long period of time, and it is small and has no protruding parts.
In this case, the switch is not operated, and the appearance is enhanced.

[0043]

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional front view showing a switch mounting structure according to an embodiment of the present invention.

FIG. 2 is a vertical sectional front view of the fluidic flow meter of the embodiment.

FIG. 3 is a vertical sectional side view of the fluidic flow meter of the embodiment.

[Explanation of symbols]

11 case, 23 channel body, 26 channel, 32 ejection nozzle, 41 piezoelectric film sensor, 47 switch case, 48 switch, 48a operation unit, 51, 52 watertight cover, 51a projecting Part, 56a ... first gap part, 5
6b: Second gap portion.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hirokazu Kanda 1-2-70, Millennial, Atsuta-ku, Nagoya-shi, Aichi Inside Aichi Watch Electric Co., Ltd. No. 10-16, Kansai Gas Meter Co., Ltd. (56) References JP-A-63-160117 (JP, A) JP-A-62-191215 (JP, U) JP-A-6-60419 (JP, U) JP 1984-82 (JP, Y2)

Claims (1)

(57) [Scope of request for utility model registration] A flow path is provided in a flow path main body enclosed in a case, and a jet nozzle for jetting a fluid into the flow path is provided, and a vibration phenomenon of the fluid jetted from the jet nozzle into the flow path is provided. In a fluidic flow meter provided with a piezoelectric membrane sensor for detecting a generated alternating pressure wave to detect a flow rate, a switch is provided in a part of the case via a switch case, and the switch case is provided with a watertight covering the switch in a watertight manner. The cover is doubled on the outside and inside, and the watertight cover on the outside
On the outside of the case.
The outer periphery of the watertight cover is engaged with the engagement groove of the switch case.
And the outer watertight cover and the inner watertight cover
Between and inside the watertight cover and switch
First and second gaps are provided between the projections,
The output amount is a, the gap amount of the first gap portion is b, and the gap amount of the second gap portion is b.
A fluid flow meter characterized in that a <(b + c) where a is the gap amount .