JP3237954B2 - 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] This fluidic flow meter is conventionally shown in FIG.
And it is comprised as shown in FIG. That is, 1
1 is a case. The case 11 includes a rectangular box-shaped case body 12 and a lid 13 that closes an opening of the case body 12. A gas inlet 14 is provided at the upper part of the case body 12, and a gas outlet 15 is provided at the lower part. A fluidic element 17 described below is installed in a lower portion inside the case 11, and a shutoff valve 18 is installed in an upper portion.

The case 11 is provided with a flow path main body 19 formed by die casting or the like. A flow path 22 is formed in the flow path main body 19 by closing an opening thereof with a lid 21 via a packing 20. 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.

[0005] A valve seat 26 is provided in the middle of the upstream flow passage 24, and a valve body 27 of the shut-off valve 18 is opposed to 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.

An ejection nozzle portion 28a having an ejection nozzle 28 is integrally 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 the ejection nozzle portion 28 a
Projecting portions 28b projecting from the upstream side flow path 24 on both side edges of the
28b to extend the nozzle passage length.

Further, 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 further provided 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 ejected to the downstream flow path 25 is subjected to the Coanda effect, for example, to the right side wall 34a.
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 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 downstream side flow path 2
It is configured such that an alternating pressure wave is generated by the vibration phenomenon of the fluid ejected into the inside 5. Further, a flow sensor 40 for measuring a minute flow rate region and a piezoelectric film sensor 41 for measuring a large flow rate region are provided at the bottom of the flow path main body 19 corresponding to the ejection nozzle 28.
The flow sensor 40 includes a sensor main body 42 and a flow detection unit 4.
3, the sensor main body 42 is fixed to the back surface portion 19a of the flow path main body 19, and the flow rate detecting section 43 is connected to the ejection nozzle 28.
It is facing.

That is, the flow sensor 40 is installed at a position where the flow path is narrowed and the flow velocity is the fastest.
The flow detecting section 43 needs to be electrically insulated, and cannot be directly attached to the flow path main body 19.

Therefore, in the prior art, FIGS.
As shown in FIG. 7, a concave portion 44 is provided at an end of the jet nozzle portion 28a on the bottom side of the flow path main body 19, and an opening 45 is formed in the bottom of the flow path main body 19 facing the concave portion 44. The opening 45 is made of a non-conductive material, and the bottom 46
The insulation protection chap 46 having the opening 46b is inserted into the recess 46a, and the bottom 46a is joined to the recess 44.

Further, the flow detecting portion 43 of the flow sensor 40 is inserted into the insulating protective cap 46, the sensor main body 42 is fixed to the bottom of the flow passage main body 19 by a fixing screw 47, and the flow detecting portion 43 is ejected from the opening 46b. It faces the nozzle 28.

[0015]

However, as described above, the concave portion 44 is provided at the bottom end of the flow path main body 19 of the jet nozzle portion 28a, and the concave portion 44 has the bottom portion of the separate insulating protection chap 46. 46a is inserted, it is difficult to assemble with the center a of the ejection nozzle 28 and the center b of the insulating protection cap 46 aligned, and the misalignment c is likely to occur between them.

As described above, when the misalignment c occurs between the center a of the ejection nozzle 28 and the center b of the insulating protective cap 46, the flow rate detecting portion 4 of the flow sensor 40 is attached to the insulating protective cap 46.
When 3 is inserted and fixed, the flow rate detection unit 43 is biased with respect to the ejection nozzle 28, which adversely affects the instrumental performance of the fluidic flow meter and the measurement performance of the flow sensor 40. In addition, the above-described mounting structure increases the number of parts, deteriorates the assembling workability, and increases the cost.

The present invention has been made in view of the above circumstances, and an object thereof is to accurately position and fix a flow detecting portion of a flow sensor at a center position of an ejection nozzle, and to provide a fluidic flow meter. An object of the present invention is to provide a fluidic flow meter capable of improving differential performance and measurement performance of a flow sensor, reducing the number of parts and assembling steps, and reducing costs.

[0018]

SUMMARY OF THE INVENTION The present invention provides
In order to achieve the above object, an ejection nozzle portion having an ejection nozzle for ejecting a fluid and a fluidic element are provided in a channel main body constituting the channel, and a vibration phenomenon of the fluid ejected into the channel from the ejection nozzle is provided. In a fluidic flow meter provided with a piezoelectric membrane sensor for detecting a generated alternating pressure wave to measure a large flow rate region and a flow sensor for measuring a minute flow rate region, the ejection nozzle portion is separated from a flow path main body. The ejection nozzle portion is provided with a fitting recess which is fitted in an electrically insulated state with the flow detecting portion of the flow sensor, and the center of the fitting recess and the center of the ejection nozzle are formed in the ejection nozzle portion. Has been matched.

The ejection nozzle portion is formed of a non-conductive material provided separately from the flow path main body, and a fitting concave portion is provided in the ejection nozzle portion, so that the flow detecting portion of the flow sensor is directly fitted. Simply by inserting the flow rate detecting unit into the concave portion, the flow rate detecting unit is necessarily installed in a state in which it is aligned with the center of the ejection nozzle.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the accompanying drawings. As shown in FIGS. 1 and 2, the flow path 22 is partitioned into an upstream flow path 24 and a downstream flow path 25 by a partition wall 23 provided integrally with the flow path main body 19 formed by die casting or the like. . A notch 50 that communicates the upstream flow path 24 and the downstream flow path 25 with a part of the partition wall 23.
Is provided.

An ejection nozzle portion 51 integrally formed of a non-conductive material such as a polymer resin is inserted into the notch portion 50, and is integrally fixed to the partition wall 23.
At the center of the ejection nozzle portion 51, a slit-shaped ejection nozzle 52 that opens over the entire depth direction of the flow path main body 19 is provided.
Are provided on both side edges of the ejection nozzle portion 51, and have protruding portions 51a, 51a that protrude into the upstream flow path 24 to extend the nozzle passage length.

Further, the flow path main body 19 of the ejection nozzle portion 51
A cylindrical protruding cylindrical portion 53 is provided integrally with the ejection nozzle portion 51 on the back surface portion 19a side, and the protruding cylindrical portion 53 fits into a fitting hole 19b formed in the back surface portion 19a of the flow path main body 19. It is fixed. The inside of the protruding cylindrical portion 53 is formed in a cylindrical fitting recess 54 communicating with the ejection nozzle 52, and the center d of the fitting recess 54 matches the center e of the ejection nozzle 52.

Accordingly, the projecting cylindrical portion 53 formed integrally with the ejection nozzle portion 51 has a fitting concave portion 54 which opens to the back surface portion 19a of the flow path main body 19.
Are formed on the insulating protection part of the flow detection part 43 of the flow sensor 40. That is, since the ejection nozzle portion 51 is formed of a non-conductive material, the fitting concave portion 54 integrated therewith is insulated on the bottom surface and the inner peripheral surface, so that a separate insulating protection cap as in the related art can be provided. Without using it, the flow detection unit 43 of the flow sensor 40 can be insulated and protected.

That is, as shown in FIG.
9, the flow detecting unit 43 of the flow sensor 40 is inserted into the fitting recess 54 from the back surface 19 a side, and the sensor main body 42 is fixed to the back surface 19 a of the flow path main body 19 with the fixing screw 55, whereby Can be positioned at the center e of the ejection nozzle 43.

[0025]

As described above, according to the present invention, the ejection nozzle portion is formed of a non-conductive material provided separately from the flow path body, and the ejection nozzle portion detects the flow rate of the flow sensor. By providing a fitting recess that fits in an electrically insulated state with the part, the center of the fitting recess matches the center of the ejection nozzle, improving the instrumental performance of the fluidic flow meter and the measurement performance of the flow sensor. Can be achieved. Further, there is an effect that a conventional insulating protective cap is not required, the number of parts and the number of assembling steps can be reduced, and the cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view taken along line AA of FIG. 2, showing a main part of a fluidic flow meter showing one 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 front view of a conventional fluidic flow meter.

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

FIG. 5 is a sectional view taken along the line BB in FIG. 3;

FIG. 6 is an enlarged sectional view showing a portion C in FIG. 5;

[Explanation of symbols]

17 Fluidic element, 19 Flow path body, 22 Flow path, 40 Flow sensor, 41 Piezoelectric film sensor, 43
Flow rate detection unit, 51: ejection nozzle unit, 52: ejection nozzle,
54 ... fitting recess.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-3226013 (JP, A) JP-A-1-168824 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01F 1/00-9/02

Claims (1)

(57) [Claims] 1. An alternating pressure caused by a vibration phenomenon of a fluid ejected into a flow path from an ejection nozzle, wherein an ejection nozzle portion having an ejection nozzle for ejecting a fluid and a fluidic element are provided in a flow path main body constituting the flow path. In a fluidic flow meter provided with a piezoelectric film sensor that measures a large flow rate region by detecting a wave and a flow sensor that measures a minute flow rate region, the ejection nozzle portion is provided separately from the flow path main body. The ejection nozzle portion is provided with a fitting recess which is fitted in an electrically insulated state with the flow rate detecting portion of the flow sensor, and the center of the fitting recess coincides with the center of the ejection nozzle. Fluidic flowmeter characterized by having made it.