JPH0791990A - Whistle type flow meter - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a flowmeter having a simple structure and capable of measuring the flow rate of a fluid which is not electrically conductive and which can be easily made compact. (A) A fluid inlet 1a, a resonance space 1c in which the fluid resonates, a small ball 1d movable with the fluid in the resonance space 1c, and an outlet 1b through which the fluid after rotational movement flows out. And a sound producing unit 1 having a whistle structure having an edge 1e provided in the outlet 1b in a direction opposite to a fluid inflow direction, and (b) a resonance space 1c of the sound producing unit 1.
Sound collecting means such as a microphone 2 for collecting the sound generated from the sound generating unit 1 by the resonance of the fluid and the movement of the small balls 1d, and (c) the sound generating unit 1 among the frequency components of the output signal from the sound collecting means. Cycle detecting means for detecting the cycle of the level decrease of the fundamental frequency component of the sound generated by,
(D) A flow meter is constituted by the flow rate calculation means 6 which calculates the flow rate of the fluid based on the cycle of the level decrease of the fundamental frequency component from the predetermined relational expression of the flow rate and the cycle.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a whistle type flow meter which measures the flow rate of a fluid such as gas or liquid using a whistle structure.

[0002]

2. Description of the Related Art Conventionally, many flowmeters for measuring the flow rate of gas or liquid have been known and can be classified into various types according to the principle, structure or use. For example, a volumetric flow meter has a built-in movable part such as a rotor and a piston, so that a fixed volume of fluid is discharged from the measuring space formed by the movable part and a case in one cycle of the movable part. Therefore, the flow rate can be known by counting the number of cycles of the movable part. Turbine flow meters belong to this type. On the other hand, when an electromagnetic flowmeter applies a magnetic field at right angles to the flow direction of a conductive fluid, an electrode placed at a position orthogonal to both the flow direction of the fluid and the magnetic field is proportional to the flow velocity and the strength of the magnetic field. Since electric power is generated, if the strength of the magnetic field is kept constant, an electromotive force proportional to the flow velocity is obtained, and since the flow velocity is proportional to the flow amount, the flow amount can be measured. As described above, there are acoustic flowmeters (including ultrasonic flowmeters), thermal flowmeters, throttle flowmeters that use orifices, and the like, as flowmeters of the type that have no moving parts in the flow path.

By the way, since the capacitive flowmeter has a movable part, flow resistance of fluid is generated, there is a limit to downsizing, and it is difficult to deal with a failure, so that there is a limit to its application. In addition, since the electromagnetic flowmeter measures only the conductive fluid, there is a limit to the fluid that can be measured. Other flow meters also have their own strengths and weaknesses.

As described above, since the flowmeters have different operating principles and structures, one type cannot satisfy all requirements, and it is important to select an appropriate flowmeter according to the application. The inventor tried an experiment focusing on a whistle represented by a whistle used by a conductor of a train or a physical education teacher.
It was found that when the blown air volume was gradually increased from 0 liter per hour at 1500 liters or less, there was a substantially linear relationship between the blown air volume and the frequency of the generated sound. Therefore, the present inventor paid attention to the fact that the flow rate can be measured by utilizing this fact, and regarding the whistle type flow meter which measures the flow rate from the frequency of the sound generated in this air volume (flow rate) region as of September 16, 1993. Filed a patent application.

[0005]

However, when the air volume, that is, the flow rate exceeds this region (1200 to 1500 liters per hour), there is no linear relationship between the flow rate and the frequency of the generated sound, so that the flow rate is different from the frequency of the generated sound. There is a problem that can not be measured.

Therefore, the present inventor has noticed that a small ball is included in the whistle to soften the sound of the whistle, and when the whistle is blown, the small ball rotates and the generated sound changes periodically, and the book It is an object of the present invention to provide a flowmeter which has a simple whistle structure in the air volume (flow rate) region where a stable sound is produced and can measure the flow rate of a fluid that is not electrically conductive and which can be easily made compact.

[0007]

According to one aspect of the present invention, in order to achieve the above-mentioned object, (a) a fluid inlet, a resonance space in which the fluid resonates, and a resonance space in the resonance space. A whistle structure sounding unit having a small ball movable with the fluid and an outlet through which the fluid after the rotational movement flows out, the edge being provided at the outlet in a direction opposite to the inflow direction of the fluid; ) Sound collecting means for collecting a sound generated from the sound generating unit due to the resonance of the fluid in the resonance space of the sound generating unit and the movement of the small balls; and (c) the frequency component of the output signal from the sound collecting means, Cycle detecting means for detecting the cycle of the level decrease of the fundamental frequency component of the sound generated by the sounding unit, and (d) the relational expression between the predetermined flow rate and the cycle, based on the cycle of the level decrease of the fundamental frequency component of the fluid. Calculate the flow rate To constitute a flow meter by the flow rate calculating means.

According to another aspect of the present invention, (a) a fluid inlet, a resonance space in which the fluid resonates, a small ball movable with the fluid in the resonance space, and the fluid after the rotational movement. A sound generating unit having a whistle structure in which an edge is provided in the outlet in a direction opposite to the inflow direction of the fluid, and (b) the resonance of the fluid in the resonance space of the sound generating unit Sound collecting means for collecting the sound generated from the sounding unit by the movement of the sphere; and (c) detecting the cycle of the frequency component of the sound generated by the small sphere among the frequency components of the output signal from the sound collecting means. Cycle detection means,
(D) A flowmeter is constituted by a flow rate calculating means for calculating the flow rate of the fluid based on the cycle already detected from the relational expression between the predetermined flow rate and the cycle.

[0009]

According to the present invention, when the fluid flows into the sounding unit, the sound is emitted from the sounding unit due to the resonance of the fluid in the resonance space and the rotational movement of the small balls.
The sound is collected by the sound collecting means to detect the cycle of the level decrease of the fundamental frequency component or the cycle of the frequency component of the sound generated by the movement of the small ball, and the flow rate and the cycle prepared in advance by experiments. From the relational expression of, the flow rate is calculated by the flow rate calculation means based on the already detected period.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings.

FIG. 1 shows a whistle type flow meter for measuring a gas flow rate as an embodiment of the present invention.

The whistle type flow meter is composed of a gas line 10a,
A whistle structure sounding unit 1 is connected in the middle of 10b, a microphone 2 for collecting the sound generated from the sounding unit 1 when gas is flowing is attached to a part, and is included in a signal extracted from the microphone 2. The noise is removed through the low-pass filter 3, and the signal level is set below the resolution of the next spectrum analyzer 4 by the low-pass filter 3, and the signal level is analyzed by the spectrum analyzer 4 for each frequency to obtain digital data. The next counter / timer 5 focuses on the fundamental frequency component of the sound emitted by the sounding unit 1 in the digital output data from the spectrum analyzer 4 and counts the number of times that the level of the fundamental frequency component is below a predetermined threshold value. Then, the time required for the count value to reach a predetermined value is measured. In the flow rate calculator 6, the fluctuation cycle of the sound emitted from the sounding unit 1 is obtained based on the data from the counter / timer 5 (this fluctuation cycle corresponds to the cycle T in which the small sphere 1d rotates in the resonance space 1c). The flow rate Q is obtained from the table showing the relationship between the cycle T and the flow rate Q, which is prepared in advance, and the result is displayed on the display unit 7.

The flow rate calculator 6 may be formed of an analog circuit or a microcomputer. The display 7 displays the flow rate Q calculated by the flow rate calculator 6 digitally or in analog form, and a liquid crystal display or a pointer meter is used.

FIG. 2 is a perspective view of the sounding unit 1, and FIG. 3 is a longitudinal sectional view of the sounding unit 1.

The sounding unit 1 of the whistle type flow meter is
As can be seen from FIGS. 1 to 3, a resin is integrally formed having a horizontally long inlet 1a for receiving gas flowing in from a pipe 10a, an outlet 1b for discharging gas to the pipe 10b, and a resonance space 1c inside. The resonance space 1c is formed of a molded body, and a small ball 1d made of, for example, cork is accommodated in a freely movable state. The inflow port 1a and the resonance space 1c are connected by a flow path P, and the outflow port 1b is formed with an edge 1e inclined in a direction opposite to the gas inflow direction. Since the inlet 1a is horizontally long, the flow velocity of the gas at the edge 1e is increased and a stable sound is produced from the sounding unit 1, and the rotational movement of the gas and the small balls 1d in the resonance space 1c is smoothly performed. Become. The resonance space 1c is shown in FIGS.
As can be seen from the above, it is preferable to make the space substantially cylindrical. Note that, as shown in FIG. 2, when the opening height of the terminal end portion S (portion opening to the resonance space 1c) of the flow path P is D and the radius when the resonance space 1c is cylindrical is R, D ≧
In the case of R, the rotational movement of the gas and the small balls 1d in the resonance space 1c becomes difficult to occur, so no sound is produced from the sound producing unit 1 and measurement becomes impossible.

A circular hole 1g is formed in one side wall 1f forming the resonance space 1c of the sound producing unit 1, and a microphone 2 is hermetically attached at this position. The holes 1g are provided in order to efficiently collect the sound generated by the sound generation unit 1. The microphone 2 may have an ordinary structure and has a frequency characteristic of 50 to 3000.
It suffices to cover H _Z , so a commercially available product will suffice. The frequency of the sound emitted from the sounding unit 1 for the same gas flow rate changes depending on the volume of the resonance space 1c of the sounding unit 1, so the frequency characteristic of the microphone 2 used may be determined by the design of the sounding unit 1.

FIG. 1 shows the output (a) of the low-pass filter 3, the output (b) of the spectrum analyzer 4, and the output (c) of the counter / timer 5.

In the whistle type flow meter having the above structure, the gas flowing in from the conduit 10a resonates in the resonance space 1c of the sounding unit 1 to generate sound, and the resonance space 1c.
The inner small ball 1d is circularly moved along the inner surface of the resonance space 1c. Assuming that the radius of the small sphere 1d is r, the force F acting on the small sphere 1d circularly moving at a speed v is F = 6πμ (U−v) r (μ is the viscosity coefficient of air, U is the moving speed of the small sphere 1d). Since the small spheres 1d circularly move at a speed according to the flow velocity of gas, the frequency of the sound generated by the sounding unit 1 when passing through the outlet 1b periodically changes. FIG. 4 shows the microphone 2
The change of the frequency of the signal output from is shown with the position of the small ball 1d.

The output signal from the microphone 2 having such a frequency change is set by the low-pass filter 3 to be equal to or lower than the resolution of the next spectrum analyzer 4, and the spectrum analyzer 4 outputs the frequency component of each sound component generated from the sound generation unit 1. Converted to level data. Since the output of the spectrum analyzer 4 includes the fundamental frequency component of the sound generated by the sound generation unit 1 and its harmonics, only the fundamental frequency component is output.

The counter / timer 5 counts the number of times that the signal level of the fundamental frequency component output from the spectrum analyzer 4 becomes equal to or lower than a predetermined threshold value, and the time required until the count value reaches a predetermined value n. Measure t. In the flow rate calculator 6, the small sphere 1d is calculated as t / n from the n and t obtained from the counter / timer 5 and the outlet 1
The period T of passing b can be obtained. In the flow rate calculator 6, the relationship between the gas flow rate Q and the cycle T as shown in FIG. 5 is preliminarily obtained through experiments and stored as a table. Therefore, from this cycle T obtained previously, the gas is calculated using this table. The flow rate Q can be calculated. In this way, the flow rate of the gas flowing through the pipelines 10a and 10b can be continuously measured by the whistle type flow meter having the above-described configuration.

FIG. 6 shows a whistle type flow meter for measuring a gas flow rate as another embodiment of the present invention.

This embodiment is a small ball 1 because of the structure of the sounding unit.
It is applied when d is larger than the resonance space 1c. When the small ball 1d is designed to be large with respect to the resonance space 1c, both the force received from the fluid and the centrifugal force are larger than when it is designed small, and the passage near the blow-in port and the blow-out port becomes smooth. On the other hand, the size of the small sphere 1d cannot be ignored, and the fundamental frequency component of the sound generated by the edge 1e is always affected by the position and speed of the small sphere 1d. Therefore, the detection method of the above embodiment is used. Becomes difficult. Therefore, in the present embodiment, attention is paid to the fact that the sound generated by the rotation of the small sphere 1d is loud, and detection is possible.

However, the level of the fundamental frequency component of the sound generated by the edge 1e becomes larger than the level of the frequency component of the sound generated by the rotation of the small ball 1d, and the frequency components of the former and the latter are relatively close to each other. Sometimes,
The latter cycle becomes difficult to detect. The present embodiment solves this point. In the figure, the same components as those of the embodiment of FIG. 1 are designated by the same reference numerals, and the description thereof will be omitted.

The signal output from the microphone 2 is subjected to noise removal by the low-pass filter 3 and is set to be equal to or lower than the resolution of the spectrum analyzer 4 in the first stage, and then the spectrum analyzer 4 in the first stage outputs the signal from the sound generation unit 1. The generated sound is converted into level data for each frequency. The output of the spectrum analyzer 4 contains harmonics in addition to the fundamental frequency component of the sound generated by the sound generation unit 1. In FIG. 6, the output of the low pass filter 3 (a), the output of the spectrum analyzer 4 of the first stage (b), the output of the spectrum analyzer 8 of the second stage (c).
Is shown.

In FIGS. 7, 8 and 9, the present inventor uses a sounding unit having a cylindrical resonance space 1c having a diameter of 15 mm and a small ball 1d having a diameter of 10 mm and a flow rate of 1250 liters each. / Hour, 1870 liters / hour,
The spectrum obtained when the gas flow rate was measured while changing it to 2490 liters / hour is shown. The horizontal axis is the sounding unit 1
The frequency of the sound generated by, and the vertical axis represents the level of each frequency component.

As can be seen from this spectrum, the generation frequency of the fundamental frequency component A of the sound generated by the edge 1e is almost constant even if the gas flow rate changes, whereas the frequency of the sound generated by the small sphere 1d. 1.400KH _z according occurrence frequency of the component B gas flow rate increases,
1.575kH _z, slide into gradually increase the 1.725kH _z. It can also be seen that the frequency component B has a smaller level than the fundamental frequency component A. For these reasons, it is difficult to obtain the frequency component B of the sound by the small sphere 1d necessary for measuring the flow rate in the present invention.

Therefore, when the output of the spectrum analyzer 4 in the first stage is sent to the spectrum analyzer 8 in the second stage, the cycle of the frequency component contained in the output of the spectrum analyzer 4 in the first stage can be extracted. FIG. 10 shows the spectrum shown in FIG. 8 (the output of the first-stage spectrum analyzer 4) processed by the second-stage spectrum analyzer 8 to find the period of each frequency component. The axis shows the gain.
As can be seen from FIG. 10, the fundamental frequency component A of the sound generated by the edge 1e and the frequency component B of the sound generated by the small ball 1d are clearly separated.

Then, the next peak detector 9 detects these two frequency components A and B, and the next digital calculator 10 calculates only the period T of the frequency component B. Since the relationship between the gas flow rate Q and the cycle T obtained in advance as shown in FIG. 5 is stored in the flow rate calculator 11 as a table, the gas flow rate is calculated using the table from the cycle T previously obtained. Q can be calculated.

As in the present embodiment, the small sphere 1d is the resonance space 1
Even in the case of a sounding unit that is larger than c, the rotation cycle of the small balls 1d can be accurately obtained, so that the flow rate can be reliably measured.

The whistle structure sounding unit used in the present invention is not limited to the one shown in the above embodiment. Inlet 1a and outlet 1b of the sounding unit 1
The shape and position of the resonance space can be freely changed according to the shape and position of the fluid conduit to be measured.
The shape of c is not limited to the cylindrical shape (the cross-sectional shape is circular), and may be an elliptical cross-section or a rectangle with rounded corners as long as it does not disturb the gas flow inside. . However, it is necessary to consider the shape of the outlet 1b so as not to disturb the movement of fluid such as gas moving in the resonance space 1c. In the case of the embodiment, since the moving direction of the gas in the resonance space 1c is limited only to the gas inflow direction, if the flow velocity is constant, the frequency of the sound generated only by the cross-sectional shape of the outlet 1b is Decided. Therefore, unless the shape of the outlet 1b is a rectangle or a square when viewed from above, sound of a uniform frequency will not be generated, and for the same reason, the end portion S of the flow path P (the portion that blows out into the resonance space 1c). (Fig. 2
The cross-sectional shape of (see) should also be rectangular. The outer shape of the resonance space 1c may be any shape as long as it does not hinder the flow of gas inside, for example, a shape having an extension in a direction perpendicular to the gas flow direction.

Further, the lengths of the end portion S of the flow path P and the edge 1e in the direction perpendicular to the gas inflow direction do not necessarily have to be the same, but neither is perpendicular to the gas inflow direction. I won't. Furthermore, the edge 1d must be sharp enough that the gas causes oscillating development. Therefore, when the sounding unit molded body is thick, the edge processing is indispensable, but when it is thin, the thickness of the end portion of the molded body may be used without processing.

The material of the small spheres 1d is preferably determined in consideration of the kind and flow velocity of the gas to be measured such as resin and styrofoam in addition to cork. Also, the shape of the small sphere is not limited to a sphere
Any shape may be used as long as it receives a force from the fluid and smoothly rotates in the resonance space.

Although the flow meter of the present invention is applied to the flow rate measurement of gas in the above embodiment, the present invention can also be applied to the flow rate measurement of liquid.

The flow meter of the present invention is intended to measure a fluid having a flow rate such that the small balls inside the sounding unit rotate in a steady state. When the flow rate of the fluid is less than that, the small balls rotate. As for the flow rate to the extent that does not occur, the fundamental frequency component of the sound generated by the sounding unit is in a linear relationship with the flow rate while the small ball remains stationary, as in the flow meter described in the section of the prior art of this specification. Since the flow rate can be measured by the processing circuit as a treatment in such a region, it is possible to measure over a wide flow rate range by devising such as switching the processing circuit of the flow meter according to the present invention according to the flow rate.

[0035]

As described above, the flowmeter of the present invention has a simple structure, can be miniaturized, can be incorporated in a narrow space, and can be particularly used for measuring a flowrate of a certain level or more. Moreover, since the movable part has an extremely simple structure, it has high reliability, it is easy to deal with a failure, and the fluid pressure loss is extremely small. Further, from the viewpoint of the operating principle, unlike the electromagnetic flowmeter, the fluid to be measured is not required to have conductivity, so that any fluid can be measured.

[Brief description of drawings]

FIG. 1 is a block diagram of a whistle type flow meter as an embodiment of the present invention.

FIG. 2 is a perspective view of a sounding unit used in the whistle type flow meter according to the present invention.

FIG. 3 is a sectional view taken along the line AA of the sounding unit shown in FIG.

FIG. 4 shows a relationship between a position of a small ball and a change in frequency of a sound generated from a sounding unit.

FIG. 5 is a graph showing a relationship between a gas flow rate Q and a cycle T.

FIG. 6 is a block diagram of a whistle type flow meter as another embodiment of the present invention.

FIG. 7 shows the level of each frequency component of the sound produced by the sounding unit for a given flow rate.

FIG. 8 is a view similar to FIG. 7 for a different flow rate than FIG.

9 is a view similar to FIG. 7 for a different flow rate than FIG.

10 shows a cycle of each frequency component with respect to the flow rate shown in FIG.

[Explanation of symbols]

 1 Sounding Unit 1a Inlet 1b Outlet 1c Resonance Space 1d Small Ball 1e Edge 2 Microphone 3 Low-pass Filter 4, 8 Spectrum Analyzer 5 Counter / Timer 6, 11 Flow Rate Calculator 10 Indicator 10a, 10b Pipeline

Claims (5)

[Claims] 1. A fluid inlet, a resonance space in which the fluid resonates, a small sphere movable with the fluid in the resonance space, and an outlet through which the fluid after rotational movement flows out. A whistle structure sounding unit having an edge provided at the outlet in a direction opposite to the fluid inflow direction, and collecting sound generated from the sounding unit by the resonance of the fluid in the resonance space of the sounding unit and the movement of the small balls. A sound collecting means, a cycle detecting means for detecting a cycle of level reduction of a fundamental frequency component of a sound generated by the sounding unit among frequency components of an output signal from the sound collecting means, and a relationship between a predetermined flow rate and a cycle A whistle type flow meter, comprising: a flow rate calculating means for calculating the flow rate of the fluid based on the formula based on the cycle of the level decrease of the fundamental frequency component. 2. The whistle type flow meter according to claim 1, wherein the sound collecting means is mounted in the vicinity of the resonance space. 3. A spectrum analyzer for analyzing the output signal from the sound collecting means as a level for each frequency by the period detecting means, and a level of a fundamental frequency component of a sound generated by the sounding unit is less than a predetermined value for a predetermined number of times. The whistle type flow meter according to claim 1, comprising a counter / timer for measuring a time required for the flow rate to decrease. 4. A fluid inlet, a resonance space in which the fluid resonates, a small sphere movable with the fluid in the resonance space, and an outlet through which the fluid after the rotational movement flows out. A whistle structure sounding unit having an edge provided at the outlet in a direction opposite to the fluid inflow direction, and collecting sound generated from the sounding unit by the resonance of the fluid in the resonance space of the sounding unit and the movement of the small balls. Sound collecting means, cycle detecting means for detecting the cycle of the frequency component of the sound generated by the small balls among the frequency components of the output signal from the sound collecting means, and the relational expression between the predetermined flow rate and the cycle A whistle type flow meter, comprising: a flow rate calculating means for calculating a flow rate of a fluid based on a cycle of a frequency component of a sound generated by a small ball. 5. The period detecting means analyzes the output signal from the sound collecting means as a level for each frequency, and the output from the first spectrum analyzer is generated by an edge of a sounding unit. A second spectrum analyzer for analyzing the period of the fundamental frequency component of the sound and the period of the frequency component of the sound generated by the small sphere, and the frequency component of the sound generated by the small sphere from the output of the second spectrum analyzer. The whistle type flow meter according to claim 4, further comprising a digital calculator for detecting a cycle.