JP3272084B2 - Fluid 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.

That is, the fluidic flow meter is shown in FIGS.
It is configured as shown in FIG. 11 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.

The gas inlet 1 is located above the case body 12.
4 is provided, and a gas outlet body 15 is provided at a lower portion. 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.

Reference numeral 19 denotes a flow passage main body formed by die casting or the like. A side opening 19a is provided on one side surface of the flow passage main body 19, and the side opening 19a is covered by a packing 20 as a sealing material. The channel 21 is closed by the body 21. This flow path 22 is a partition 2
3, the upstream flow path 24 communicates with the gas inlet body 14, and the downstream flow path 25 communicates with the gas outlet body 1.
5 is connected.

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 integrally with the partition wall 23 of the flow path main body 19. The jet nozzle 28 has a slit shape that opens over the entire depth direction of the flow path main body 19, and has protrusions 28 a and 28 b that protrude into the upstream flow path 24 on both side edges in the longitudinal direction thereof. The passage length is extended. Further, a side opening 29 that opens in the same direction as the side opening 19 a of the flow path main body 19 is provided on one side surface of the ejection nozzle 28.

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 provided further downstream. Is provided. Return passages 37a, 37b are formed outside the side walls 34a, 34b, and discharge passages 38a,
38b are provided.

As described above, the side opening 19a of the flow path main body 19 is formed.
And the side opening 29 of the ejection nozzle 28
The cover 21 is closed and fixed to the flow path main body 19 by a plurality of tightening screws 30.

[0014]

By the way, the flow path main body 1
9 through a packing 20 to cover 21 side opening 19a.
The structure which is closed by the seal cannot be reliably sealed unless it is strongly tightened by the tightening screw 30.

However, in the flow channel body 19, the flow channel 22 is surrounded by the peripheral wall 19b, and the flow channel 22 has a jet nozzle 28, a first target 33, a side wall 34a,
34b, a second target 35, a return wall 36 and the like are protruded, and return flow paths 37a and 37b and a discharge path 38
a, 38b are formed.

Therefore, the side opening 19 of the flow path main body 19 is formed.
a is an uneven surface, and this uneven surface is
It is closed by. Therefore, the packing 20 formed of an elastic material such as rubber bends with the lapse of time and swells into the concave portion forming the flow path 22.

If the tightening force of the plurality of tightening screws 30 varies, the inner surface of the packing 20 becomes wavy, and particularly, the packing 20 at the portion opposed to the side opening 29 of the jet nozzle 28 swells and the jet nozzle 20 This causes a problem that the opening cross section of the ejection nozzle 28 is reduced, which affects the pressure loss and varies the instrument difference performance.

The present invention has been made in view of the above circumstances, and an object thereof is to suppress variations in instrumental performance without deteriorating the sealing performance and to stabilize the characteristics over a long period of time. It is an object of the present invention to provide a fluidic flow meter which can be designed.

[0019]

In order to achieve the above object, the present invention has a side opening on one side, and the side opening is closed by a lid via a sealing material to form a flow path. A flow path main body, a partition provided in the flow path main body and partitioning the flow path into an upstream flow path and a downstream flow path, and a side opening closed by a lid via the sealing material on the partition. In a fluid flow meter comprising a jet nozzle having a fluidic element provided in the downstream flow path, a step portion lower than the outer peripheral edge of the end surface is provided at the inner peripheral edge of the peripheral surface of the peripheral surface of the flow channel body, and the step portion is provided. Fit a rigid cover plate that closes the entire side opening of the channel body to the
The lid is provided outside the cover plate via the sealing material.

[0020]

Since the uneven surface of the side opening of the flow path main body is closed by a rigid covering plate, the packing does not bend into the flow path and does not bite into the ejection nozzle. It is possible to maintain a constant cross-sectional area and eliminate variations in instrumental differences.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the accompanying drawings.

FIGS. 1 to 3 show the whole of a fluidic flow meter, in which a flow channel 22 inside a flow channel body 19 is surrounded by a peripheral wall 41, and an inner peripheral edge of an end surface of the peripheral wall 41 has an outer peripheral edge 41a of an end surface. A lower step portion 41b is provided.

The partition wall 23, the ejection nozzle 28, the first target 33, the side walls 34a and 34b, the second target 35, and the return wall 36 projecting from the bottom surface of the flow path 22 of the flow path body 19 are formed by the peripheral wall 41. Is formed at the same height as the step portion 41b.

Further, a plurality of screw holes 42 are provided in the outer peripheral edge 41a of the end face of the peripheral wall 41, and the outer peripheral edge of a cover plate 43 for closing the side opening 19a of the flow path main body 19 is joined to the step portion 41b.

The cover plate 43 is made of a rigid material such as a metal plate and has the same thickness as the depth of the step portion 41b, and is designed so that the cover plate 43 is flush with the outer peripheral edge 41a of the end face. ing.

The packing 20 is joined to the outside of the cover plate 43, and the lid 21 is further joined to the outside of the packing plate 43.
, The side opening 19 a of the flow path main body 19 is closed by a triple structure of the cover plate 43, the packing 20 and the lid 21, and the flow path main body 19 and the lid 21 are sealed by the packing 20.

Therefore, the side opening 19 of the flow path body 19
Even if there is an uneven portion in the flow path 2, the packing 20 does not bite into the flow path 22 or the ejection nozzle 28 by the cover plate 43 so that the packing 20 does not bite into the flow path 2.
2 and the opening cross-sectional area of the ejection nozzle 28 can be kept constant, thereby eliminating variations in instrumental differences.

In the above-described embodiment, the fluidic flow meter having the inlet 14 at the upper part of the flow path body 19 and the outlet 15 at the lower part has been described. The present invention is also applicable to a fluidic flow meter having an inlet body 14 and an outlet body 15 arranged side by side.

[0029]

As described above, according to the present invention, since the uneven surface of the side opening of the flow path main body is closed by the rigid cover plate, the packing changes due to aging and the variation in the tightening force of the tightening screw. Does not bend into the flow path or penetrate into the ejection nozzle, the opening cross-sectional area of the flow path and the ejection nozzle can be kept constant, and variations in instrumental differences can be eliminated, and long-term stability of performance can be achieved. There is an effect that can be.

[Brief description of the drawings]

FIG. 1 is a partially cutaway side view of a fluidic flow meter according to a first embodiment of the present invention.

FIG. 2 is a front view showing the internal structure of the fluidic flow meter of the embodiment.

FIG. 3 is a longitudinal sectional side view showing part A of FIG. 1 in an enlarged manner.

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

FIG. 5 is a front view showing the internal structure of the fluidic flow meter.

FIG. 6 is a longitudinal sectional side view showing a portion B in FIG. 4 in an enlarged manner.

[Explanation of symbols]

17: Fluidic element, 19: Flow path body, 20: Packing, 21: Lid, 22: Flow path, 23: Partition wall, 24
... upstream flow path, 25 ... downstream flow path, 28 ... ejection nozzle,
19a: side opening, 41: peripheral wall, 41a: outer peripheral edge of end face, 41b: stepped portion, 43: cover plate.

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Naoshi Isshiki 1-2-3 Shimura, Itabashi-ku, Tokyo Inside Kinmon Manufacturing Co., Ltd. (56) References Patent 3017832 (JP, B2) Patent 2983072 (JP, B2) Patent 2709203 (JP, B2) Patent 3009935 (JP, B2) Patent 2517401 (JP, B2) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01F 1/20

Claims (1)

(57) [Claims] 1. A flow path main body having a side opening on one side and closing the side opening with a lid via a sealing material to form a flow path, and a flow path provided in the flow path main body. A partition partitioning into an upstream flow path and a downstream flow path, an ejection nozzle having a side opening closed by a lid via the sealing material in the partition, and a fluidic provided in the downstream flow path In the fluidic flow meter comprising the element, a step portion is provided at an inner peripheral edge of an end face of the peripheral wall of the flow path main body, which is lower than an outer peripheral edge of the end face, and the step has a rigid cover for closing the entire side opening of the flow path main body. A fluid flow meter, wherein a plate is fitted, and the lid is provided outside the cover plate via the sealing material.