JP3267448B2 - Fluidic flow meter and fluidic oscillation detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluidic flow meter used for a gas meter and the like, and a fluidic oscillation detecting device for detecting a change in the direction of flow of a fluid passing through a nozzle in the fluidic flow meter. .

[0002]

2. Description of the Related Art In a fluidic flow meter, a flow path enlarged portion is formed by a pair of side walls on a downstream side of a nozzle for generating a jet flow, and a fluid passing through the nozzle is formed by a return guide provided outside the side walls. Is formed along the outer side of each side wall to the nozzle outlet side of the nozzle, and a phenomenon in which fluid passing through the nozzle alternately flows through the pair of feedback channels (hereinafter referred to as fluidic oscillation). The flow rate of the fluid is measured based on the switching frequency of the direction in which the fluid flows through the nozzle.

Here, an example of a fluidic flow meter used as a gas meter will be described with reference to FIG. The fluidic flow meter includes a main body 110 having an inlet 111 for receiving gas (gas) and an outlet 112 for discharging gas. A partition 113 is provided in the main body 110, a first gas channel 114 is formed between the partition 113 and the inlet 111, and a second gas channel 115 is formed between the partition 113 and the outlet 112. Are formed. An opening 116 is provided in the partition 113 and the first
A shutoff valve 117 capable of closing the opening 116 is provided in the gas flow path 114. A solenoid 118 is fixed to the outside of the main body 110.
Eight plungers 119 are connected to the shutoff valve 117 through the side wall of the main body 110. A spring 120 is provided around the plunger 119 between the shutoff valve 117 and the main body 110.
17 is urged toward the opening 116 side.

The second gas flow path 115 has an inlet 11
There is provided a nozzle 121 for generating a jet by passing the gas received from the nozzle 1. A rectifying member 122 for adjusting the flow of gas is provided upstream of the nozzle 121. Downstream of the nozzle 121, a pair of side walls 123 and 124 that form an enlarged flow path are provided. A first target 125 is disposed on the upstream side and a second target 126 is disposed on the downstream side at predetermined intervals between the side walls 123 and 124. In addition, outside the side walls 123 and 124, the gas that has passed through the nozzle 121 is applied to the nozzle 12 along the outer periphery of each side wall 123 and 124.
A pair of feedback channels 1 that return to the ejection port side 1
A return guide 129 forming the parts 27 and 128 is provided. In addition, between the outlets of the feedback channels 127 and 128 and the outlet 112, a pair of discharge channels 1 is provided by the back surface of the return guide 129 and the main body 110.
31 and 132 are formed. In the vicinity of the ejection port of the nozzle 121, pressure guiding holes 133 and 134 are provided to communicate with a differential pressure sensor for detecting a change in the direction of flow of the gas passing through the nozzle 121.

FIG. 9 shows the pressure guiding holes 133 and 134 in FIG.
FIG. 2 is an enlarged cross-sectional view showing a cross section including a differential pressure sensor. As shown in this figure, a differential pressure sensor 137 that detects a differential pressure using a piezoelectric film or the like is provided outside the bottom of the main body 110.
Is provided. In addition, the pressure guiding holes 133 and 134 have
One end of each of the pressure guiding tubes 151 and 152 is connected. The other ends of the pressure guiding tubes 151 and 152 are connected to the differential pressure sensor 1.
37 are connected to each pressure inlet. Then, the differential pressure sensor 137 detects the pressure guiding holes 133 and 134.
Is detected, and fluidic oscillation is detected based on the change in the differential pressure. Also,
The pressure guiding tubes 151 and 152 and the differential pressure sensor 137 are covered by a case 155 fixed to the outside of the bottom of the main body 110.

[0006]

By the way, in the fluidic flow meter shown in FIG. 8, even when the same pressure is applied to the pressure guiding holes 133 and 134, that is, even when the differential pressure is zero, the piezoelectric pressure of the differential pressure sensor 137 is reduced. The pressure is hardly canceled on the left and right sides of the piezoelectric film due to the unevenness of the left and right sides of the film.
There is a problem that the output of the 37 is hard to become zero.

Further, the fluidic flow meter shown in FIG. 8 has a low resistance to external noise, which is a high-frequency pressure fluctuation generated by nearby construction vibrations and the like, and a fluctuation in fluid pressure, and has a poor S / N ratio. There is a problem. FIG.
(A) has shown an example of the pressure fluctuation. The maximum width of the pressure fluctuation is 16 mmH ₂ O. FIG.
10B illustrates an example of the output of the differential pressure sensor 137 with respect to the pressure fluctuation illustrated in FIG. This differential pressure sensor 1
The maximum width of the fluctuation of the output of 37 is 68.8 mV. When the fluctuation of the output of the differential pressure sensor 137 with respect to the pressure fluctuation is large, the output fluctuation may be erroneously detected as a change in the output of the differential pressure sensor 137 due to fluidic oscillation. FIG. 11 shows an example of the frequency characteristic of the pressure fluctuation, and FIG. 12 shows an example of the frequency characteristic of the output of the differential pressure sensor 137 with respect to the pressure fluctuation of the characteristic shown in FIG. From these figures, it can be seen that the fluidic flow meter shown in FIG. 8 has low resistance to pressure fluctuations.

The present invention has been made in view of the above problems, and has as its object to reduce the error output when the same pressure is applied to the left and right pressure guiding holes and to withstand external noise and fluid pressure fluctuations. It is an object of the present invention to provide a fluidic flow meter and a fluidic oscillation detecting device which can improve the measurement accuracy and improve the measurement accuracy.

[0009]

According to a first aspect of the present invention, there is provided a fluidic flow meter, comprising: an inlet for receiving a fluid; a nozzle for passing a fluid received from the inlet to generate a jet from an outlet; A pair of side walls provided on the downstream side and forming an enlarged flow path, and a pair of side walls provided outside the side walls and returning the fluid passing through the nozzle to the nozzle outlet side along the outside of each side wall. A return guide that forms the feedback flow path, an outlet that discharges the fluid that has passed through the feedback flow path, and pressure guiding holes provided on the left and right sides of the nozzle outlet, and is connected to the pressure guiding hole;
In order to detect a change in the direction in which the fluid flows through the nozzle, the pressure sensor includes a pressure sensor that detects a pressure difference between the left and right pressure guiding holes and a bypass path that bypasses between the left and right pressure guiding holes.

In this fluidic flow meter, the fluid that has passed through the nozzle flows alternately through a pair of feedback channels. The pressure sensor detects a pressure difference between the left and right pressure guiding holes in order to detect a change in the direction in which the fluid flowing through the nozzle flows. In addition, the bypass passage equalizes the left and right pressures applied to the pressure sensor when the same pressure is applied to the left and right pressure guiding holes, and cancels and removes external noise and fluid pressure fluctuation.

A fluid oscillation detector according to a second aspect of the present invention is for detecting a change in the direction of flow of a fluid passing through a nozzle in a fluidic flow meter, and is provided on both left and right sides of a nozzle outlet. A pressure sensor connected to the pressure guiding hole, a pressure sensor for detecting a pressure difference between the left and right pressure guiding holes, and a left and right pressure guiding hole for detecting a change in the direction of flow of the fluid passing through the nozzle. And a bypass path for bypassing the space.

In this fluidic oscillation detecting device, the pressure sensor detects a pressure difference between the left and right pressure guiding holes in order to detect a change in the direction of flow of the fluid passing through the nozzle. In addition, the bypass passage equalizes the left and right pressures applied to the pressure sensor when the same pressure is applied to the left and right pressure guiding holes, and cancels out external noise and pressure fluctuation of the fluid,
Remove.

[0013]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a sectional view showing the structure of a fluidic flow meter according to a first embodiment of the present invention. The present embodiment is an example of a fluidic flow meter used as a gas meter. As shown in FIG. 1, the fluidic flow meter of the present embodiment includes a main body 10 having an inlet 11 for receiving gas (gas) and an outlet 12 for discharging gas. A partition 13 is provided in the main body 10.
A first gas flow path 14 is formed between
A second gas passage 15 is formed between the partition 13 and the outlet 12. An opening 16 is provided in the partition 13, and a shutoff valve 17 capable of closing the opening 16 is provided in the first gas flow path 14. A solenoid 18 is fixed to the outside of the main body 10, and a plunger 19 of the solenoid 18 penetrates a side wall of the main body 10 and is joined to the shutoff valve 17. A spring 20 is provided around the plunger 19 between the shut-off valve 17 and the main body 10.
The spring 20 urges the shutoff valve 17 toward the opening 16.

In the second gas passage 15, there is provided a nozzle 21 for passing the gas received from the inlet 11 to generate a jet. A rectifying member 22 for regulating the flow of gas is provided upstream of the nozzle 21. Downstream of the nozzle 21, a pair of side walls 23 and 24 that form an enlarged flow path are provided. This side wall 2
A predetermined interval is left between 3, 24, and the first
A target 25 and a second target 26 are provided on the downstream side, respectively. In addition, outside the side walls 23 and 24,
A return guide 2 that forms a pair of feedback channels 27 and 28 that return the gas that has passed through the nozzle 21 to the ejection port side of the nozzle 21 along the outer peripheral portions of the side walls 23 and 24.
9 are provided. Also, the feedback channel 27,
28, a pair of discharge paths 3 is provided between the outlet portion 12 and the outlet portion 12 by the back surface of the return guide 29 and the main body 10.
1, 32 are formed. In the vicinity of the nozzle 21, pressure guiding holes 33 and 34 are provided to communicate with a differential pressure sensor for detecting a change in the direction of flow of the gas passing through the nozzle 21.

FIG. 2 is an enlarged sectional view showing a section including the pressure guiding holes 33 and 34 and the differential pressure sensor in FIG.
As shown in this figure, a differential pressure sensor 37 as a pressure sensor for detecting a differential pressure using a piezoelectric film or the like is provided outside the bottom of the main body 10. Further, one ends of pressure guiding tubes 51 and 52 are connected to the pressure guiding holes 33 and 34, respectively. The other ends of the pressure guiding tubes 51 and 52 are connected to respective pressure introduction ports of the differential pressure sensor 37. The differential pressure sensor 37 detects a differential pressure between the pressure guiding holes 33 and 34 and detects fluidic oscillation based on a change in the differential pressure. In this embodiment, a bypass pipe 53 that bypasses between the pressure guiding pipes 51 and 52 is provided as a bypass path that bypasses between the left and right pressure guiding holes 33 and 34. The fluid introduction holes 33 and 34, the differential pressure sensor 37, and the bypass pipe 53 constitute a fluidic oscillation detection device in this embodiment. Further, the pressure guide tubes 51 and 52, the bypass tube 53, and the differential pressure sensor 37
Is covered by a case 55 fixed to the outside of the bottom of the main body 10.

FIG. 3 is a block diagram showing a configuration of a circuit portion of the fluidic flow meter according to the present embodiment. As shown in the figure, the fluidic flow meter has a flow rate calculator 41 that receives the output of the differential pressure sensor 37 and calculates a flow rate, and a display section 42 that displays the flow rate calculated by the flow rate calculator 41. And a solenoid drive circuit 43 controlled by the flow rate calculation unit 41 to drive the solenoid 18. The flow rate calculator 41 binarizes the output of the differential pressure sensor 37 into “+1” and “0”, generates “+1” and “0” pulses, and counts the number of pulses per unit time. Thus, the switching frequency of the direction in which the gas flowing through the nozzle 21 flows is obtained, and this frequency is converted into a flow rate. The fluidic flow meter according to the present embodiment has a safety function when used as a gas meter, for example, when the flow rate calculation unit 41 detects a flow rate equal to or more than a predetermined amount, or when the flow rate detection unit detects a predetermined flow amount for a predetermined time or more. Then, the solenoid drive circuit 43 is operated to operate the solenoid 18, and the valve 17 closes the opening 16 to shut off gas. The flow rate calculation unit 41 is realized by, for example, a microcomputer.

Next, the operation of the fluidic flow meter of this embodiment will be described.

The gas received from the inlet 11 of the fluidic flow meter passes through the first gas passage 14 and the opening 1.
6, the gas enters the nozzle 21 through the second gas flow path 15 and the flow regulating member 22 in this order.

The gas that has passed through the nozzle 21 is jetted out of the jet port as a jet. The gas ejected from the ejection port flows along one side wall due to the Coanda effect. Here, it is assumed that the flow first flows along the side wall 23. The gas flowing along the side wall 23 is further fed into the feedback channel 2.
7, and is returned to the ejection port side of the nozzle 21, and the discharge path 3
1 through the outlet 12. At this time, the direction of the gas ejected from the nozzle 21 is changed by the gas flowing through the feedback channel 27, and the gas then flows along the other side wall 24. This gas is further returned to the ejection port side of the nozzle 21 through the feedback flow path 28 and discharged from the outlet section 12 through the discharge path 32. Then, the direction of the gas ejected from the nozzle 21 is changed by the gas flowing through the feedback channel 28, and the side wall 23 and the feedback channel 2 are returned again.
It flows along 7. By repeating the above operation, the gas that has passed through the nozzle 21 flows alternately through the pair of feedback channels 27 and 28. The switching frequency of this gas flow direction has a correspondence with the flow rate.
The frequency at which the direction of flow of the gas passing through the nozzle 21 is switched is determined by the flow rate calculation unit 41 based on the output of the differential pressure sensor 37. The flow rate calculation unit 41 calculates the flow rate from the determined frequency and displays the flow rate on the display unit 42. Also,
The flow rate calculation unit 41 operates the solenoid drive circuit 43 to operate the solenoid 18 when detecting a flow rate equal to or more than a predetermined amount or detecting a predetermined flow rate for a predetermined time or more. The blockage is made, and the supply of gas to the downstream side of the fluidic flow meter is stopped.

The first target 25 and the second target 26 have an effect of stably switching the flow direction of the gas passing through the nozzle 21.

In the present embodiment, the pressure guiding tubes 51, 5
A bypass pipe 53 for bypassing between the two is provided.
The bypass pipe 53 equalizes the left and right pressures applied to the differential pressure sensor 37 when the same pressure is applied to the left and right pressure guiding holes 33 and 34, cancels the left and right pressures, and reduces the error output. In addition, even when there is external noise, which is high-frequency pressure fluctuation generated by nearby construction vibrations, or gas pressure fluctuation, the external noise and gas pressure fluctuation are canceled and removed by the bypass pipe 53. Therefore,
Immunity to external noise and gas pressure fluctuations is improved.
Although the amplitude of the change in the differential pressure due to the fluidic oscillation is also reduced by the bypass pipe 53, the amplitude of the change in the differential pressure due to the fluidic oscillation is compared with the amplitude of the change in the differential pressure due to the external noise and the pressure change of the gas. Has no effect on the detection of fluidic oscillation. As described above, according to the present embodiment, the measurement accuracy of the fluidic flow meter is improved.

FIG. 4A shows an example of pressure fluctuation. The maximum width of the pressure fluctuation is 16 mmH ₂ O. FIG. 4B shows an example of the output of the differential pressure sensor 37 with respect to the pressure fluctuation shown in FIG. The maximum width of the fluctuation of the output of the differential pressure sensor 37 is 32.8 mV. As is apparent from a comparison between FIG. 4B and FIG. 10B, it can be seen that the provision of the bypass pipe 53 reduces the fluctuation of the output of the differential pressure sensor 37 with respect to the pressure fluctuation.

FIG. 5 shows an example of the frequency characteristic of the pressure fluctuation, and FIG. 6 shows an example of the frequency characteristic of the output of the differential pressure sensor 37 with respect to the pressure fluctuation of the characteristic shown in FIG.
As is apparent from a comparison between FIG. 6 and FIG. 12, the provision of the bypass pipe 53 reduces pressure fluctuations (noise) in the vicinity of several hundreds of Hz indicated by symbols A and A ′ in FIGS. I understand.

FIG. 7 is an enlarged sectional view showing a section including the pressure guiding holes 33 and 34 and the differential pressure sensor in the fluidic flow meter according to the second embodiment of the present invention. As shown in this figure, the present embodiment is different from the first embodiment in that
Instead of this, the main body 10 is provided with a bypass passage 54 that bypasses the left and right pressure guiding holes 33 and 34.

Other structures, operations and effects are the same as those of the first embodiment.

The present invention is not limited to the above embodiments. For example, instead of the differential pressure sensor 37, each pressure guiding hole 3
3, two pressure sensors connected to each other are provided.
The flow rate may be calculated by calculating the pressure difference between the pressure guiding holes 33 and 34 from the outputs of the two pressure sensors.

Further, in each of the above embodiments, the fluidic flow meter for measuring the flow rate of gas such as gas has been described. However, the fluidic flow meter of the present invention is used as a flow meter for measuring the flow rate of not only gas but also liquid. Can also be used.

[0029]

As described above, according to the present invention, the bypass passage is provided to bypass between the left and right pressure guiding holes.
The error output when the same pressure is applied to the left and right pressure guiding holes is reduced, and resistance to external noise and pressure fluctuation of the fluid is improved, so that the measurement accuracy is improved.

[Brief description of the drawings]

FIG. 1 is a sectional view showing the configuration of a fluidic flow meter according to a first embodiment of the present invention.

FIG. 2 is an enlarged sectional view showing a section including a pressure guiding hole and a differential pressure sensor in FIG. 1;

FIG. 3 is a block diagram showing a configuration of a circuit portion of the fluidic flow meter according to the first embodiment of the present invention.

FIG. 4 shows the pressure fluctuation of gas and FIG. 2 for this pressure fluctuation.
FIG. 6 is a waveform chart showing an example of the output of the differential pressure sensor in FIG.

FIG. 5 is a characteristic diagram illustrating an example of a frequency characteristic of pressure fluctuation.

6 is a characteristic diagram showing an example of a frequency characteristic of an output of the differential pressure sensor in FIG. 2 with respect to a pressure fluctuation of the characteristic shown in FIG.

FIG. 7 is an enlarged sectional view showing a section including a pressure guiding hole and a differential pressure sensor in a fluidic flow meter according to a second embodiment of the present invention.

FIG. 8 is a cross-sectional view showing a configuration of an example of a fluidic flow meter used as a gas meter.

FIG. 9 is an enlarged sectional view showing a section including a pressure guiding hole and a differential pressure sensor in FIG. 8;

FIG. 10 is a waveform chart showing an example of a pressure fluctuation of a gas and an output of the differential pressure sensor in FIG. 9 with respect to the pressure fluctuation.

FIG. 11 is a characteristic diagram illustrating an example of a frequency characteristic of pressure fluctuation.

12 is a characteristic diagram showing an example of the frequency characteristic of the output of the differential pressure sensor in FIG. 9 with respect to the pressure fluctuation of the characteristic shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Inlet part 12 Outlet part 21 Nozzle 23, 24 Side wall 27, 28 Feedback flow path 29 Return guide 33, 34 Pressure guiding hole 37 Differential pressure sensor 51, 52 Pressure guiding hole 53 Bypass pipe

Claims (2)

(57) [Claims] An inlet for receiving a fluid, a nozzle for passing a fluid received from the inlet to generate a jet from an outlet, and an enlarged flow path provided downstream of the nozzle. A pair of side walls, a return guide provided outside the side walls, and forming a pair of feedback flow paths for returning the fluid passing through the nozzle to the nozzle outlet side along the outside of each side wall; An outlet for discharging the fluid that has passed through the flow path; and pressure guiding holes provided on both the left and right sides of the nozzle of the nozzle; connected to the pressure guiding hole to switch the direction of flow of the fluid that has passed through the nozzle. A fluid sensor, comprising: a pressure sensor for detecting a pressure difference between the left and right pressure guiding holes, and a bypass path for bypassing between the left and right pressure guiding holes. The amount meter. 2. A fluidic oscillation detecting device for detecting a change in a direction of flow of a fluid passing through a nozzle in a fluidic flow meter, comprising: a pressure guide hole provided on both left and right sides of a nozzle of the nozzle. A pressure sensor that is connected to the pressure guiding hole and detects a pressure difference between the left and right pressure guiding holes to detect a change in the direction of flow of the fluid that has passed through the nozzle; and bypasses between the left and right pressure guiding holes. A fluidic oscillation detection device comprising a bypass path.