JP2754376B2 - Soap film flow meter - Google Patents

Description

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

[Conventional technology]

Currently, the types of flow meters that measure gas flow are:
There are a mass flow meter and a volume flow meter, and one of the volume flow meters is a soap film flow meter. This soap film type flow meter is widely used because it has 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. 63-30977. In addition, a soap film that moves 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 is provided on the lower side of the volume tube. The time T required to pass between the start detector and the stop detector provided on the upper side of the volume tube is measured, and the time T and the volume value of the volume tube between the two detectors (soap within the time T). The flow rate S (= V / T) of the measurement gas is determined from the volume value (V) swept by the film.

By the way, such a soap film type flow meter cannot obtain an accurate flow rate without correcting the temperature of the measurement gas and the atmospheric pressure (atmospheric pressure) at the time of measurement due to the measurement principle. The atmospheric pressure is separately measured to compensate for the influence of the temperature of the measured gas and the atmospheric pressure.

The atmospheric pressure can be easily measured by a barometer. However, it is ideal to directly measure the temperature of the measurement gas by inserting a thermometer in the center of the volume tube.In this case, however, the shape of the soap film is affected. There is a problem that an error occurs.

Therefore, conventionally, the temperature of the portion where the volume tube is provided, that is, the ambient temperature is measured and this is regarded as the temperature of the measurement gas. In addition, a heat medium such as water or oil is caused to flow through the soap tube through the soap film, and the temperature of the heat medium is controlled to an appropriate temperature.

[Problems to be solved by the invention]

However, according to the above-described means, when the moving speed of the measurement gas in the volume tube is slow and the measurement time is sufficiently long, the measurement accuracy can be secured because there is almost no difference between the temperature of the measurement gas and the ambient temperature. If the measurement gas is dry and has a relatively large flow rate, a difference occurs between the temperature of the measurement gas and the ambient temperature, and the measurement accuracy decreases. This is because when the dry measurement gas is humidified with the soap liquid in the volume tube, it is cooled by the heat of vaporization of the soap liquid and the temperature of the measurement gas decreases.

In order to avoid this, when the measurement gas is dry, it is conceivable to provide a humidifier or a cooling device in the gas flow path to the volume pipe and appropriately perform pretreatment before the measurement gas is introduced into the volume pipe. . However, in this case, the simplicity of the structure,
The advantages of the soap film flow meter, such as small size and light weight, are impaired.

Further, according to the above means, the structure of the volume tube is complicated.
As the size increases, the mounting becomes troublesome, and in this case, the above advantages are lost.

The present invention has been made in consideration of the above-mentioned matters, and an object of the present invention is to accurately grasp the temperature of a measurement gas without deteriorating its original advantage, thereby reducing the flow rate of the measurement gas. An object of the present invention is to provide a soap film type flow meter capable of accurately measuring.

[Means for solving the problem]

In order to achieve the above object, the soap film type flow meter according to the present invention is provided with a temperature sensor on the outer wall of a volume tube through which the measurement gas and the soap film pass.

[Action]

According to the above configuration, it is possible to measure a temperature as close as possible to the temperature of the measuring gas passing through the volume tube without affecting the shape of the soap film.

〔Example〕

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

FIG. 1 is a perspective view showing an example of a soap film type flow meter according to the present invention, and FIG. 2 is a block diagram schematically showing the configuration thereof.

In FIG. 1, 10 is a volume tube unit, 20 is a main unit, and the volume tube unit 10 is detachably attached to the main unit 20 by a set lever 21 provided on the main unit 20.

As shown in FIG. 2, the volume tube unit 10 has a cylindrical volume tube made of glass having appropriate strength.
11 is provided in a vertical state, and an inlet 12 and an outlet 13 for a measurement gas are provided at appropriate positions on the lower side and the upper side.

Further, a bellows-shaped soap liquid storage unit 15 is provided slightly below the inlet 12 through the connection unit 14 and connected to the lower part of the volume tube 11. The soap liquid storage section 15 is configured to be pushed up by operating a soap film generation operation lever 28 described later downward to form a predetermined soap film.

In addition, the volume tube 11 is provided with a start detector 16 slightly above the inlet 12 and a stop detector 17 below the outlet 13, and each of the detectors 16 and 17 is a pair of light emitting elements. And a light-receiving element, and each time the soap film passes through the start detector 16 or the stop detector 17, the clocking by the clocks connected to these detectors 16 and 17 is started or stopped.

The volume value V between the detectors 16 and 17 of the volume tube 11 is strictly measured, and the volume value V is set in a volume value setting unit 18 composed of, for example, a digital switch.

As shown in FIG. 2, a signal reading section 22 for reading detection signals from the detectors 16 and 17 and a start detector 16 based on the signal from the signal reading section 22 are provided in the main unit 20. The time T from when the soap film is detected until the stop detector 17 detects the soap film
And a calculation unit 23 for calculating the flow rate V of the measurement gas from the time T and the volume value V.
The arithmetic unit 23 is provided with a microprocessor 24 and a clock pulse oscillator 25 for generating a pulse used as a basis for time calculation.
It is composed of

The main unit 20 includes the signal reading unit 22 and the arithmetic unit 2.
In addition to 3, a connector 26, a flow rate display unit 27, a soap film generation operation lever 28, and the like are provided. The soap film generation operation lever 28 is provided such that one end thereof is in contact with the bottom of the soap solution storage unit 15, and the bottom is pushed up by operating the soap film generation operation lever 28 downward, whereby the bottom is pushed up. Soap is pushed up and volume tube 11
A predetermined soap film is formed therein. Reference numeral 29 denotes a volume value reading unit that reads the volume value V of the volume tube 11 set in the volume value setting unit 18.

The configuration described above is no different from a conventional soap film flow meter of this type. The present invention is characterized in that a temperature sensor 19 is provided on the outer wall 11A of the volume tube 11 in the volume tube unit 10. That is, as shown in FIG. 3, the temperature sensor 19 is attached using an appropriate adhesive 30 so as to be in close contact with the outer wall 11A between the start detector 16 and the stop detector 17 of the volume tube 11, and The temperature of 11A is detected. As the temperature sensor 19, a thermistor, a thermocouple, a semiconductor sensor, or the like is used. The detection signal from the temperature sensor 19 is input to the microprocessor 24 in the main unit 20 via the connector 26. Note that this microprocessor
In 24, a measurement value from a barometer (not shown) is also input.

Next, the operation of the soap film type flow meter having the above configuration will be described.

The measuring gas enters the volume tube 11 via the inlet 12. At this time, when the soap film generation operation lever 28 is operated downward to push up the soap solution in the soap solution storage portion 15, a soap film is formed at the connection portion 14, and the soap film is pushed up by the measurement gas and has a volume. It moves upward in the pipe 11. If the inner surface of the volume tube 11 is well wetted with the soap solution in advance, the soap film passes through the start detector 16, and further, the soap film passes through the stop detector 17. By passing through the soap film, the start detector 16 and the stop detector 17 operate, the start and stop of time measurement are performed, and signals are output from the respective detectors 16 and 17.

The signals from the detectors 16 and 17 are read by a signal reading unit 22, and based on the signal from the signal reading unit 22, in the calculation unit 23, after the start detector 16 detects the soap film, the stop detector 17 The time T until the soap film is detected is calculated, and this time T
From the volume value V between the detectors 16 and 17 of the volume tube 11, the flow rate V of the measurement gas in the measurement state is calculated. At this time, since the temperature signal from the temperature sensor 19 and the pressure signal from the barometer (not shown) are input to the calculation unit 23, the flow rate V calculated using these signals is corrected. Thereby, the flow rate in the standard state is obtained.

In this embodiment, as shown in FIG.
Is mounted so as to be in close contact with the outer wall 11A of the volume tube 11, but the volume tube 11 is thin and the temperature sensor 19
If the temperature sensor 19 is thermally integrated with the outer wall 11A, it can be considered that the temperature sensor 19 measures the temperature of the measurement gas in the volume tube 11. However, actually, as shown in FIG. 5 (A), the temperature in the volume tube 11 is not always uniform. In this figure, 16, 19, and 17 are a start detector 16, a temperature sensor 19, and a stop detector 17.
Indicates the position where each is provided. Further, as shown in FIG. 3B, the position also differs depending on the elapsed time (T ₁ <T ₂ <T ₃ ) from the start of the measurement, and further, the flow rate of the measurement gas passing through the volume tube 11 ( It also depends on Q ₁ <Q ₂ <Q ₃ ).

Therefore, it is preferable to consider the following to determine the positions where the start detector 16, the stop detector 17, and the temperature sensor 19 are provided.

That is, when there is no distribution (difference) in the temperature at each of the above positions, the start detector 16, the stop detector
17, There is no special restriction on the installation position of the temperature sensor 19 and the like.
In particular, when the measurement gas has a small flow rate, a uniform soap film may be formed. When there is a distribution in the temperature at each of the positions, the temperature difference between them is as small as possible, and even if the time changes, the temperature difference between them does not change much. It is necessary to make the temperature difference at

The present invention is not limited to the above-described embodiment, and can be implemented with various modifications.

For example, in order to attach the temperature sensor 19 to the outer wall 11A of the volume tube 11, a flat portion 11a is formed on the outer wall 11A as shown in FIG. 19 may be fixed, and FIG.
As shown in FIG. 5, a protrusion 11b may be formed on the outer wall 11A, and the temperature sensor 19 may be fixed so as to be surrounded by the protrusion 11b.Furthermore, a recess 11c is formed on the outer wall 11A, and the recess 11c is formed. The temperature sensor 19 may be fixed inside. In any of these cases, the contact area between the outer wall 11A and the temperature sensor 19 increases, and the temperature of the gas in the volume tube 11 can be detected more reliably.

〔The invention's effect〕

As described above, in the present invention, since the temperature sensor is provided on the outer wall of the volume tube through which the measurement gas and the soap film pass, the temperature of the measurement gas can be controlled without affecting the shape of the soap film. Can be accurately grasped,
Thus, the flow rate of the measurement gas can be accurately measured.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an example of a soap film type flow meter according to the present invention, FIG. 2 is a block diagram schematically showing its structure, FIG. 3 is a view showing a mounting portion of a temperature sensor, FIG. (A), (B), (C) is a diagram showing another mounting mode of the temperature sensor, and FIGS. 5 (A), (B), (C) are diagrams showing a temperature distribution in the volume tube. 11 ... Volume tube, 11A ... Outer wall, 16 ... Start detector, 17 ... Stop detector, 19 ... Temperature sensor.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G01F 1/00-3/38

Claims (2)

(57) [Claims] 1. A start detector provided on a lower side of the volume tube, wherein a soap film moving upward from below in the volume tube by a measurement gas introduced into the volume tube provided in the up-down direction, and the volume detector. A soap film type in which the flow rate of the measurement gas is measured based on the time required to pass between a stop detector provided on the upper side of the tube and the volume value of the volume tube between the two detectors. A soap film type flow meter, wherein a temperature sensor is provided on an outer wall of the volume tube. 2. The soap film type flow meter according to claim 1, wherein the position where the temperature sensor is provided is between the two detectors.