JP3215574B2 - Whistle type 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 whistle-type flow meter for measuring a flow rate of a fluid such as gas or liquid by utilizing a whistle structure.

[0002]

2. Description of the Related Art Conventionally, many flow meters for measuring the flow rate of a gas or a liquid are known, and are classified into various types based on principles, structures, applications, and the like. For example, a positive displacement flow meter such as a turbine flow meter has a built-in movable part such as a rotor and a piston, and a fixed volume of fluid is discharged in one cycle of the movable part from a measurement space formed by the movable part and a case. The flow rate can be known by counting the number of cycles of the movable part. On the other hand, when an electromagnetic flowmeter applies a magnetic field perpendicular to the direction of flow of a conductive fluid, an electrode placed at a position orthogonal to both the direction of flow of the fluid and the magnetic field causes an electromotive force 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 can be obtained. Since the flow velocity is proportional to the flow rate, the flow rate can be measured. As described above, examples of the flow meter having no movable portion in the flow path include an acoustic flow meter (including an ultrasonic flow meter), a heat flow meter, and a throttle flow meter using an orifice. However, the positive displacement flowmeter has a movable part, which causes a flow resistance of the fluid, and has a limitation in downsizing, and has a drawback that it is difficult to cope with a failure. Other flow meters also have their own disadvantages.

[0003]

In the sports whistle type whistle, the flow rate and the sound emission frequency are proportional in a low flow rate range.
By utilizing this phenomenon, a compact and highly reliable sports whistle-type whistle-type flow meter that has a simple structure with no moving parts and can measure the flow rate even of non-conductive fluids will be developed. Became.

FIG. 9 is a block diagram of a conventional whistle type flow meter.

The whistle-type flow meter measures the flow rate of gas. A sound-generating unit 1 having a whistle structure is connected in the middle of gas pipes 10a and 10b. A microphone 2 for collecting sounds emitted from the sounding unit 1 is attached to a part of the microphone, components outside the measurement target range included in a signal output from the microphone 2 are removed via a high-cut filter 3, and the signal is subjected to hysteresis (see FIG. 5). A waveform is shaped by comparing with a constant value by a comparator 4 multiplied by the waveform (b) shown by a broken line), and the pulse signal output from the comparator 4 is counted by a counter / timer 5 to obtain a frequency. Based on the calculated flow rate, a flow rate is calculated from a predetermined relational expression, and the calculated gas flow rate is displayed on the display unit 7.

FIG. 8 is a perspective view showing a schematic configuration of a sounding unit used in a conventional whistle-type flowmeter of a sports whistle type.

The sounding unit 1 shown in FIG. 8 is a whistle of a sports whistle type, and has side walls 1e on both sides (see FIG. 9).
Are omitted from the drawing. A horizontally long inlet 1a for receiving gas flowing from the gas line 10a and a mouthpiece 1f including a gas flow path connected thereto, an outlet for discharging gas to the gas line 10a, that is, an acoustic hole 1b, and a cylindrical cavity, It is a resin molded product including a resonance space 1c and an edge 1d, and the inflow port 1a and the resonance space 1c communicate with each other.
The edge 1d is formed at the outlet 1b so as to be inclined in a direction opposite to the gas inflow direction. Outer wall 1e of resonance space 1c
The microphone 2 is hermetically attached here.

FIG. 4 is a dimensional diagram of a whistle of a sports whistle type used in the experiment.

A whistle-type flow meter using a sports whistle-type whistle as shown in FIG. 4 has a flow rate of 200 L / H.
The frequency of the whistle sound is linearly proportional to the flow rate in the range from 700 L / H to 700 L / H. When 800 L / H or more is applied, the rate of increase in the transmission frequency of the whistle sound becomes gentle, and becomes even constant at a higher flow rate. . Therefore, when trying to expand the measurement range of this flowmeter, the linear range is expanded by enlarging the body of the flowmeter, or another oscillating element corresponding to the flow rate by incorporating a small ball in the flowmeter. Will have to be added or done. Increasing the size of the main body is against the miniaturization of the flow meter, and incorporating a small ball is contrary to not having a movable part in the flow path of the flow meter, and further incorporating a small ball. It is necessary to selectively use two types of arithmetic methods, that is, the case where the operation is performed and the case where the operation is not incorporated, by the conditional branch. In both methods, the signal-to-noise ratio slightly deteriorates in the original measurement range.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and has a small and simple structure without a built-in globule, thereby expanding a linear proportional range between a flow rate of a flowing fluid and a transmission frequency of a whistle sound. It is an object of the present invention to provide a whistle type flow meter capable of measuring a flow rate up to a high flow rate region.

[0011]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention has a mouthpiece into which a fluid flows, an outlet for discharging the fluid, and a slope formed in the outlet so as to be opposed to the gas inflow direction. A sounding unit having an edge, sound collecting means for collecting sounds generated by the sounding unit, and passing a fundamental frequency component of a sound generated by the sounding unit among frequency components output from the sound collecting means. Filter means, frequency detecting means for detecting the frequency of the fundamental frequency component, and computing means for computing the flow rate of the fluid based on the frequency of the fundamental frequency component from a predetermined relational expression between the flow rate and the frequency. It is characterized by.

Further, according to the present invention, the sounding unit is housed in a box in a sealed manner, the mouthpiece of the sounding unit protrudes from the box, and a discharge port for fluid exiting the sounding unit is provided on the outer wall of the box. It is characterized by.

Further, the present invention is characterized in that a fluid inflow pipe is connected to the mouthpiece of the sounding unit, and the measured fluid that has passed through the acoustic hole is discharged into the atmosphere.

[0014]

According to the present invention, when the fluid flows into and out of the sound generating unit, sound is generated by the edge element.
Further, the fluid is discharged from the box housing the sounding unit, and the sound is collected by the sound collecting means, and the fundamental frequency component is detected through the filter means. The flow rate is calculated by the calculating means based on the detected frequency component from the relational expression of the flow rate and the frequency specific to the sounding unit prepared in advance.

[0015]

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

FIG. 5 is a perspective view of the basic elements of a sports whistle type whistle used in the experiment.

The frequency of the sound generated when the whistle is blown lightly seems to be proportional to the blowing amount. The inventor of the present invention sought a new frequency output type flow meter using this fact as a hint to extract the desired structure from the whistle, and (a) the entire whistle, (b) the edge element, and (c) the cavity element. (See FIG. 5), and the role played by each element in generating sound was examined by experiments. As a result, it was found that the edge element (b) exhibits the following characteristics in the whistle of the sports whistle type tested in this experiment.

FIG. 3 is a graph showing characteristics of a sound based on an edge element.

In the graph of FIG. 3, the horizontal axis indicates gas flow rate (unit: liter / hour), and the vertical axis indicates sound frequency (unit: Hertz). According to this graph, it can be seen that the frequency of the sound based on the edge element, that is, the edge tone, is linearly proportional to the flow rate in the range of 200 to 1400 liter / hour. The present invention employs this point in a flow meter.

FIG. 1 is a block diagram of a whistle type flow meter according to the present invention. FIG. 2 is a diagram showing a schematic configuration of a sound generating unit used in the whistle type flow meter of the present invention.

The whist used in the present invention is of the sports whistle type, but as shown in FIG. 2, the cavity or resonance space existing in the conventional whistle type flow meter is removed and only the edge element is used. It is characterized by:

FIG. 6 is a graph showing the relationship between each sound generation phenomenon and the generation frequency when the strength of blowing gas into the whistle alone is changed in three stages A, B, and C.

The whistle of the sports whistle type has three sound phenomena of (A) Helmholtz resonance, (B) edge tone and (C) cavity tone as shown in FIG. Therefore, a phenomenon that emits the loudest sound at a certain flow rate is detected as whistle sound. The horizontal axis in FIG. 6 indicates the frequency, and the vertical axis indicates the output voltage of the microphone.

FIG. 7 is a graph showing the characteristics of the main sound generated by the whistle.

In the above-mentioned conventional whistle type flow meter, the relationship between the flow rate and the sound frequency changes at a certain flow rate.
This is because it is different from the high flow rate side and (B) the low flow rate side. Therefore, (A) the cavity that causes Helmholtz resonance, that is, the resonance space is removed, and the structure is changed to (B) a structure that generates only the edge tone (see FIG. 2) by the edge element.
The present invention is such that the effect of the (B) edge tone appears up to the high flow rate region.

The embodiment of FIG. 1 is described as measuring gas flow. The main part is a sounding unit 10 having a whistle structure. A cubic box 11 is connected in the middle of the gas pipelines 10a and 10b, and the sounding unit 10 is housed in the box 11 in a sealed state. A mouthpiece 1f of the sounding unit 10 projects from the front wall of the box 11 in a sealed state, and a gas pipe 10a is hermetically connected thereto. The gas pipeline 10a is connected to a rear end (exit end) of, for example, a chimney or an exhaust pipe. Therefore, when measuring the displacement at the smoke outlet, the above box 11 becomes unnecessary. That is, the box 11 does not necessarily need to be attached.
Further, the gas outlet from the sounding unit 10 is
1, a gas line 10b is hermetically connected to the outlet. Gas box 1 if box 11 is not installed
0b is directly discharged into the atmosphere without being connected.

The sounding unit 10 shown in FIG. 2 is shown without the side walls 1e (shown in FIG. 1) on both sides for easy understanding of the structure. This sounding unit 10
As described above, a sports whistle-type whistle is modified so that the edge tone effect appears even in a high flow rate region, and is constituted by the following three elements. That is, a horizontally long gas inlet 1a for introducing gas flowing from the gas pipeline 10a, a mouthpiece 1f including a gas flow path (not shown) connected thereto, and a gas outlet 1b for discharging gas into the box 11. And an edge 1d. The edge 1d is formed in the gas outlet 1b so as to be inclined in a direction opposite to the gas inflow direction. A hole is formed in the side wall 1e of the sounding unit 10 and the microphone 2 is hermetically connected thereto. The microphone 2 is connected to the high cut filter 3, the comparator 4, the counter / timer 5, the flow rate calculator 6 outside the side wall 10 c of the box 11, and further connected to the display 7.

Gas is supplied from the gas line 10a to the sound generating unit 1
0, passes through the sounding unit 10 and passes through the gas line 10
The microphone 2 collects sounds emitted by the sounding unit 10 when the sound is emitted from the microphone b. A comparator 4 that removes components outside the measurement target range included in the signal output from the microphone 2 through the high-cut filter 3 and applies the signal to hysteresis (shown by a broken line in the waveform (b) shown in FIG. 1). The pulse signal output from the comparator 4 is shaped into a counter / timer 5
The flow rate is calculated from a predetermined relational expression in the flow rate calculation section 6 based on this frequency, and the gas flow rate of the calculation result is displayed on the display 7.

[0029]

As described above, the whistle-type flow meter of the present invention has a mouthpiece into which a fluid flows, an outlet for discharging the fluid, and a slant in the direction opposite to the fluid flowing direction. Since the sounding unit having the formed edge is the main component and the edge tone is used for measuring the flow rate, the range in which the flow rate of the fluid passing through this whistle type flow meter and the transmission frequency of the sound are linearly proportional. It is twice as large as before and can measure the flow rate up to the high flow rate area,
Further, since there is no movable portion in the flow path, the structure is small and the structure is simple.

[Brief description of the drawings]

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

FIG. 2 is a diagram showing a schematic configuration of a sound generating unit used in the whistle type flow meter of the present invention.

FIG. 3 is a graph showing characteristics of a sound based on an edge element.

FIG. 4 is a dimensional diagram of a sports whistle type whistle used in the experiment.

FIGS. 5A and 5B are perspective views of basic elements of a sports whistle type whistle used in the experiment, wherein FIG. 5A is a diagram illustrating the entire whistle, FIG. 5B is a diagram illustrating an edge element, and FIG.

FIG. 6 is a graph showing the relationship between each sound generation phenomenon and the generation frequency when the strength of blowing gas into a single whistle is changed in three stages.

FIG. 7 is a graph showing characteristics of a main sound generated by a whistle.

FIG. 8 is a perspective view showing a schematic configuration of a sound generating unit used in a conventional sports whistle type whistle flow meter.

FIG. 9 is a block diagram of a conventional whistle type flow meter.

[Explanation of symbols]

 1a Gas inlet 1b Gas outlet 1c Cavity or resonance space 1d Edge 1e Side wall 1f Mouthpiece 2 Microphone 3 High cut filter 4 Comparator 5 Counter / timer 6 Flow rate calculation 7 Display 10 Sounding unit 10a Gas line 10b Gas line 10c Side wall 11 box

Claims (7)

(57) [Claims] 1. A sound generating unit having a mouthpiece into which a fluid flows, an outlet for discharging the fluid, and an edge formed in the outlet so as to be inclined in a direction opposite to a fluid inflow direction, and generated by the sounding unit. Sound collecting means for collecting a sound to be generated, a filter means for passing a fundamental frequency component of a sound generated by the sounding unit among output signal frequency components from the sound collecting means, and a frequency for detecting a frequency of the fundamental frequency component A whistle-type flow meter, comprising: a detection unit; and a calculation unit that calculates a fluid flow rate based on a frequency of the fundamental frequency component from a predetermined relational expression between the flow rate and the frequency. 2. The sounding unit is housed in a box in a hermetically sealed manner, a mouthpiece of the sounding unit protrudes from the box, and a discharge port for fluid exiting the sounding unit is provided on an outer wall of the box. The whistle type flow meter according to claim 1, wherein: 3. The whistle-type flow meter according to claim 1, wherein a fluid inlet pipe is connected to a mouthpiece of the sounding unit, and the measured fluid that has passed through the edge is discharged into the atmosphere. 4. The whistle type flow meter according to claim 1, wherein said sound collecting means is mounted near said edge. 5. The whistle type flow meter according to claim 1, wherein the sound collecting means is attached to the box without impairing airtightness. 6. The whistle-type flow meter according to claim 1, wherein said frequency detecting means is a counter / timer for counting an output signal from the sound collecting means within a predetermined time by pulsing. 7. The whistle type flow meter according to claim 1, wherein said frequency detecting means is a peak detector.