JP2802817B2 - Soap film flow meter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an improvement of a soap film type flow meter for measuring a gas flow rate.

[Conventional technology]

At present, there are a mass flow meter and a volume flow meter as types of flow meters for measuring a gas flow rate, and a soap film flow meter is one of the volume flow meters. This soap film type flow meter is widely used because of its advantages such as simplicity of structure, small size and light weight, as shown in, for example, Japanese Patent Publication No. 63-43692 and Japanese Utility Model Publication No. Sho 63-30977. To
A soap film is provided on the lower side of the volume tube, the soap film moving upward from below in the volume tube by a gas to be measured (hereinafter referred to as a measurement gas) introduced into the volume tube provided in the vertical direction. The time T required to pass between the detector and the stop detector provided on the upper side of the volume tube is measured, and this time T and the volume value of the volume tube between the two detectors (the soap film within the time T). And the flow rate S of the measurement gas (= V /
T).

By the way, in order to accurately measure the gas flow rate using such a soap film type flow meter, it is important to form a uniform thin soap film on the lower end of the volume tube with only one sheet. As shown in FIG. 3, the soap film type flowmeter has a diameter which is larger than the lower opening 31 and swings in the vertical direction with respect to the lower opening 31 of the volume tube 30 provided in the vertical direction. In some cases, a soap film 33 is formed using a film ring 32.

[Problems to be solved by the invention]

According to the above prior art, a relatively large diameter (for example, an inner diameter of 4 m
The desired soap film can be formed on the volume tube with a diameter of 2 m or more. However, in the case of a small volume tube with a small inside diameter (for example, an inside diameter of 2 mm or less) for measuring a minute flow rate, the soap film is used. May be formed doubly, and since the end face of the lower opening 31 is almost horizontal, a liquid pool due to the surface tension of the soap liquid easily occurs at the end face of the lower opening 31 by the film forming ring 32, and is thin and uniform. In some cases, it was difficult to adhere and form a perfect soap film.

The present invention has been made in consideration of the above-mentioned matters, and the purpose thereof is not only when the inner diameter of the volume tube is large, but also when the inner diameter of the volume tube is small, the lower opening of the volume tube. An object of the present invention is to provide a soap film type flow meter capable of uniformly forming a desired thin soap film and thereby accurately measuring a gas flow rate.

[Means for solving the problem]

In order to achieve the above object, the soap film type flow meter according to the present invention is formed such that an end face of the lower opening is formed into an inclined surface which is obliquely cut off so as to be inclined with respect to one direction, and the inclined lower end face of the lower opening. The lowermost end of the film receiving ring is further extended downward to extend the liquid dropping portion, and further, around the lower opening, a film receiving ring having a smaller diameter than the film forming ring and a larger diameter than the lower opening is provided. It is characterized in that it is provided below the lower opening end face.

[Action]

According to the above configuration, the soap film formed by the film forming ring is always attached to the lower opening end surface of the volume tube via the film receiving ring. Since the excess soap liquid that does not contribute to the formation of the soap film quickly drops through the liquid dropping portion, no liquid pool is formed on the lower opening end surface.
Therefore, a thin and uniform soap film can always be stably attached to the lower opening of the volume tube.

〔Example〕

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

FIGS. 1 (A) and 1 (B) show an example of the configuration of a main part of a soap film type flow meter according to the present invention. In this figure, reference numeral 1 denotes a soap liquid storage container containing a soap liquid 2 therein; On one side thereof, an inlet 3 for the measurement gas G is opened so as to be located above the level of the soapy liquid, and a volume tube 4 made of, for example, a cylindrical glass tube having appropriate strength is provided on the upper surface thereof. The lower end thereof is air-tightly erected while being inserted into the soap solution storage container 1, and is further internally mounted on the tip of a swing arm 6 which swings up and down by a solenoid 5 as a driving device. An annular film-forming ring 7 in a plan view that forms a soap film adhered to the lower opening 4A of the volume tube 4 is provided. The inner diameter of the film forming ring 7 is larger than the outer diameter of the lower opening 4A.

Reference numeral 8 denotes a swing fulcrum of the swing arm 6, reference numeral 9 denotes a weight, and reference numeral 10 denotes a transmission member that transmits the output of the solenoid 5 to the swing arm 6. The volume tube 4 is provided with a start detector 11 above the lower opening 4A and the upper opening 4B.
The stop detector 12 is provided below. Each of these detectors 11 and 12 is provided with a pair of light emitting element and light receiving element. Each time the soap film 13 in the volume tube 4 passes through the start detector 11 or the stop detector 12, it is connected to both detectors 11 and 12, respectively. The time measurement by a clock (not shown) is started or stopped, and the time T required for the soap film 13 to pass between the detectors 11 and 12 can be measured. Further, the volume value V between the two detectors 11 and 12 of the volume tube 4 is strictly measured, and the volume value V is set in a volume value setting unit (not shown) composed of, for example, a digital switch.

The configuration up to this point is not different from the conventional soap film flow meter. Although not shown, a pipe is connected to the measurement gas inlet 3.

Thus, according to the present invention, the end face of the lower opening 4A of the volume tube 4
As shown in FIG. 2 (A), 4a is formed on an inclined surface which is inclined in one direction. That is, the lower opening end surface 4a is cut off obliquely so as to be inclined from the measurement gas inlet 3 toward the swing arm 6. The lowermost end of the lower opening end face 4a is formed in the liquid dropping portion 14 by being elongated further downward, for example, in a tapered rod shape. As shown in FIGS. 2A and 2B, an annular membrane receiving ring having a smaller diameter than the film forming ring 7 and a larger diameter than the lower opening 4A is provided around the lower opening 4A. 15 is provided so as to hang from the upper inner wall 1A of the soap solution storage container 1 so that the lower end face 15A is aligned with the inclination of the lower opening end face 4a and is positioned below the lower opening end face 4a. I have.

Next, the operation of the soap film type flow meter having the above configuration will be described. Now, the measurement gas G introduced into the soap solution storage container 1 via the measurement gas inlet 3 is opened at the lower opening of the volume tube 4.
It is assumed that the gas passes through the volume tube 4 from 4A. And
When the solenoid 5 is not operated, the film forming ring 7 is at a position above the film receiving ring 15 (this is called a first position) as shown by a solid line in FIG. When the solenoid 5 is temporarily turned on, as shown by an imaginary line in FIG. 2B, the solenoid 5 is brought into a position immersed in the soap solution 2 (this is called a second position), and the first position is returned again.
Shall return to the position.

Accordingly, a soap film is formed on the film forming ring 7 while the film forming ring 7 is returning from the second position to the first position with the temporary ON operation of the solenoid 5. Is further raised, the soap film adheres to the film receiving ring 15 and a predetermined soap film 13 'is formed on the film receiving ring 15. Since the soap film 13 'blocks the flow of the measurement gas G flowing through the volume tube 4, it is deformed by the gas pressure toward the volume tube 4 as shown in FIG. It adheres to the end face 4b and seals the entrance of the volume tube 4. At this time, the excess soap liquid that does not contribute to the formation of the soap film quickly falls through the lower opening end face 4a and the liquid dropping portion 14 inclined in one direction, so that no liquid pool is generated on the lower opening end face 4a. And then
The soap film adhering to the lower opening end face 4a rises in the volume tube 4 due to the gas pressure and passes through the start detector 11 and the stop detector 12, respectively. At this time, a time T required for passing between the two detectors 11, 12 is taken. And measure
The flow rate of the measurement gas G can be obtained based on the time T and the volume value V between the two detectors 11 and 12 of the volume tube 4.

As understood from the description of the above embodiment, in the present invention, the soap film formed by the film forming ring 7 is
Since the soap film is once transferred to the membrane receiving ring 15 and then a soap film is formed on the lower opening end face 4a of the volume tube 4, the thickness of the soap film varies due to excess soap solution pumped up by the film forming ring 7. Can be prevented, and a desired thin and uniform soap film can be formed. Then, since the excess soap liquid that does not contribute to the formation of the soap film quickly drops through the liquid dropping part 14, the liquid does not accumulate on the lower opening end face 4a. Therefore, a thin and uniform soap film can always be stably attached to the lower opening 4A of the volume tube 4.

〔The invention's effect〕

Since the present invention is configured as described above, not only when the inner diameter of the volume tube is large, but also when the inner diameter of the volume tube is small, a desired thin soap film is uniformly attached to the lower opening of the volume tube. Can be formed. Therefore, according to the present invention, the gas flow rate can be accurately measured.

[Brief description of the drawings]

1 (A) and 1 (B) show an example of a configuration of a main part of a soap film type flow meter according to the present invention. FIG. 1 (A) is a front sectional view, and FIG. 1 (B) is a side sectional view. FIGS. 2 (A) and 2 (B) are enlarged views showing the vicinity of the lower opening of the volume tube.
FIG. 1A is a longitudinal sectional view, and FIG. 1B is a BB view in FIG. 1A. FIG. 3 is an enlarged longitudinal sectional view showing the vicinity of a lower opening of a conventional volume tube. 4 ... volume tube, 4A ... lower opening, 4a ... lower opening end face,
7 ... film forming ring, 13 ... soap film, 14 ... liquid dropping part, 15 ... film receiving ring, 15A ... lower end surface of film receiving link.

Claims (1)

(57) [Claims] 1. A soap film in which a soap film is attached to a lower opening of a volume tube provided in a vertical direction by using a film forming ring having a diameter larger than that of the lower opening and swinging in a vertical direction. In the membrane type flow meter, the lower opening has an end surface formed as an inclined surface which is cut obliquely so as to be inclined with respect to one direction, and the lowermost end of the inclined lower opening end surface is further drooped downward to drop the liquid. A film receiving ring having a diameter smaller than that of the film forming ring and larger than that of the lower opening is provided around the lower opening such that an end face thereof is located below an end face of the lower opening. Soap-film flowmeter.