JP3290299B2 - Fluid 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 fluid flow meter used for a gas meter or the like, and more particularly to a means for preventing dust and mist contained in a fluid from adhering to a pressure guiding hole for detecting pressure. And a fluidic flow meter having the same.

[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. Of the fluid passing through the nozzle by utilizing a phenomenon in which the fluid passing through the nozzle alternately flows through the pair of feedback channels. The flow rate of the fluid is measured based on the frequency of the switching of the flowing direction.

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 shut-off valve 117 and the main body 110, and the spring 120 is connected to the shut-off valve 117.
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. 6 is a perspective view showing the vicinity of the nozzle 121 of the fluidic flow meter shown in FIG. As shown in this figure, the pressure guiding holes 133 and 134 are
Is provided at the bottom of the main body 110 parallel to the direction of travel of the gas passing therethrough. The pressure guiding holes 133 and 134 are
10 is connected to a differential pressure sensor (not shown) provided outside the bottom portion. The differential pressure sensor detects a change in the direction in which the gas flowing through the nozzle 121 flows. In the drawing, reference numeral 138 indicates the direction of gas flow.

[0006]

However, when a fluidic flow meter as shown in FIG. 5 is used as a gas meter, dust or mist contained in the supplied gas adheres to the pressure guiding holes 133 and 134, and There is a problem that the flow rate cannot be measured accurately due to the blocks 133 and 134 being blocked.

The present invention has been made in view of the above problems, and has as its object to provide a fluid flow rate capable of preventing dust and mist contained in a fluid from adhering to a pressure guiding hole for detecting pressure. To provide a total.

[0008]

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 for forming a feedback flow path, an outlet for discharging the fluid that has passed through the feedback flow path, a pressure guide hole provided in a wall forming the jet port in the vicinity of the jet port of the nozzle; And a pressure sensor connected to the pressure hole for detecting a change in the direction in which the fluid flows through the nozzle.

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 change in pressure due to switching of a flowing direction of the fluid via the pressure guiding hole. Further, since the pressure guiding hole is provided on the wall surface forming the ejection port of the nozzle, dust and mist contained in the fluid are less likely to adhere to the pressure guiding hole.

[0010] The fluidic flow meter according to claim 2 is
2. The fluidic flowmeter according to claim 1, wherein the nozzle is arranged so that the ejection port is on the lower side, and the pressure guiding hole faces downward.

In this fluidic flow meter, since the pressure-guiding hole is directed downward, even if dust or mist adheres to the pressure-guiding hole, it does not fall under its own weight and block the pressure-guiding hole. Is done.

[0012]

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

FIG. 1 is a sectional view showing the configuration of a fluidic flow meter according to one 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.

FIG. 2 is a perspective view showing the vicinity of the ejection port of the nozzle 21 of the fluidic flow meter shown in FIG. As shown in this figure, the nozzle 21 has a vertically long ejection port 21a extending in the thickness direction of the fluidic flow meter. In the vicinity of the jet port 21a, a pair of pressure guiding holes 3 are formed on a pair of wall surfaces 21b and 21c forming the jet port 21a.
3 and 34 are provided. Also, as shown in FIG.
In the main body 10 constituting the nozzle 21, pressure guiding holes 33, 3 are provided.
4 are provided with pressure guiding passages 35 and 36. In FIG. 2, reference numeral 38 indicates the direction of gas flow.

FIG. 3 is a sectional view showing a section of the nozzle 21 including the pressure guiding hole 33 and the pressure guiding passage 35. As shown in this figure, the main body 10 forming the nozzle 21 includes a frame 10a having an open top except for an inlet 11 and an outlet 12,
And a lid 10b that covers the upper surface of the frame 10a. A differential pressure sensor 37 that detects a differential pressure using a piezoelectric film or the like is attached as a pressure sensor below the frame 10 a below the nozzle 21. Pressure guiding passage 3
Reference numerals 5 and 36 are connected to the 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 a change in the direction of fluid flow based on a change in the differential pressure.

Further, the fluidic flow meter according to the present embodiment is installed such that the inlet 11 and the outlet 12 are on the lower side as shown in FIG. Therefore, the nozzle 21 is disposed so that the ejection port 21a is on the lower side, and the pressure guiding holes 33 and 34 face downward.

FIG. 4 is a block diagram showing the configuration of the circuit portion of the fluidic flow meter of the present embodiment. As shown in the figure, the fluidic flow meter receives an output signal of the differential pressure sensor 37 as an input, and calculates a flow rate based on the input signal, and a flow rate calculated by the flow rate calculating section 41. And a solenoid drive circuit 43 that is controlled by the flow rate calculator 41 and drives 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 21a as a jet. The gas ejected from the ejection port 21a 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 returned to the ejection port side of the nozzle 21 through the feedback channel 27 and discharged from the outlet section 12 through the discharge path 31. At this time, the direction of the gas ejected from the nozzle 21 is changed by the gas flowing through the feedback flow path 27,
This time it will flow along the other side wall 24. This gas is further passed through the feedback passage 28 to the nozzle 2.
1 is returned to the ejection port side, and the outlet 12
Is more exhausted. Then, the direction of the gas ejected from the nozzle 21 is changed by the gas flowing through the feedback flow path 28, and flows again along the side wall 23 and the feedback flow path 27. 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. Flow rate calculator 41
Calculates the flow rate from the obtained frequency and displays it on the display unit 42. The flow rate calculation unit 41 operates the solenoid drive circuit 43 to detect the flow rate of a predetermined amount or more, or to detect the predetermined flow amount for a predetermined time or more.
8 is operated, the opening 16 is closed by the valve 17, and the supply of gas (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 this embodiment, the pressure guiding holes 33, 3
4 is provided on a pair of wall surfaces 21b and 21c forming the ejection port 21a in the vicinity of the ejection port 21a of the nozzle 21. Therefore, since the pressure guiding holes 33 and 34 are not in front of the ejection port 21a, dust and mist contained in the gas hardly adhere to the pressure guiding holes 33 and 34. Further, in this embodiment,
The nozzle 21 is arranged so that the ejection port 21a is on the lower side, and the pressure guiding holes 33 and 34 are directed downward, so that even if dust or mist adheres to the pressure guiding holes 33 or 34, the nozzle 21 is under its own weight. The pressure guiding holes 33 and 34 are prevented from falling and being blocked. Therefore, according to the present embodiment, it is possible to measure the flow rate accurately.

The pressure guiding holes 33 and 34 may be located at any position in the longitudinal direction of the jet port 21a if the pair of wall surfaces 21b and 21c forming the jet port 21a is near the jet port 21a. good. The pressure guiding holes 33 and 34 are
A plurality of pairs may be provided instead of a pair.

Further, instead of the differential pressure sensor 37, two pressure sensors connected to the pressure guiding passages 35 and 36 are provided,
The flow rate may be calculated from the outputs of the two pressure sensors.

In the above embodiment, the fluidic flow meter for measuring the flow rate of gas such as gas has been described.
The fluidic flow meter of the present invention can be used as a flow meter for measuring the flow rate of not only gas but also liquid.

[0027]

As described above, according to the fluidic flow meter according to the first aspect, the pressure guide hole is provided in the pair of wall surfaces forming the ejection port in the vicinity of the ejection port of the nozzle. There is an effect that dust and mist contained in the fluid can be prevented from adhering to the pressure guiding holes.

According to the fluidic flow meter of the present invention, since the pressure-guiding hole is directed downward, in addition to the above-mentioned effects, even if dust or mist adheres to the pressure-guiding hole, the weight of the fluid increases. And the pressure guiding hole can be prevented from being blocked.

[Brief description of the drawings]

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

FIG. 2 is a perspective view showing the vicinity of an ejection port of a nozzle of the fluidic flow meter shown in FIG.

FIG. 3 is a cross-sectional view showing a cross section of a nozzle including a pressure guiding hole and a pressure guiding passage in the fluidic flow meter shown in FIG.

FIG. 4 is a block diagram showing a configuration of a circuit portion of a fluidic flow meter according to one embodiment of the present invention.

FIG. 5 is a sectional view showing a configuration of an example of a fluidic flow meter used as a gas meter.

FIG. 6 is a perspective view showing the vicinity of a nozzle of the fluidic flow meter shown in FIG. 5;

[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 35, 36 Pressure guiding passage 37 Differential pressure sensor

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; a pressure guiding hole provided in a wall forming the nozzle in the vicinity of the nozzle of the nozzle; and a pressure guiding hole connected to the pressure guiding hole and passing through the nozzle. And a pressure sensor for detecting a change in the flowing direction of the fluid. 2. The fluidic flowmeter according to claim 1, wherein the nozzle is arranged so that a jet port is located on a lower side, and the pressure guiding hole is oriented on a lower side.