JP3295532B2 - 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 fluid flow meter having an asymmetrical flow path.

[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. The pressure guiding holes 133 and 134 are connected to a differential pressure sensor (not shown) provided outside the bottom of the main body 110. The differential pressure sensor detects a change in the direction in which the gas flowing through the nozzle 121 flows.

[0005]

By the way, in the fluidic flow meter shown in FIG.
The shape of the portion up to 12 (hereinafter referred to as an element portion) is symmetrical. On the other hand, the center line 151 of the element portion in the left-right direction does not match the center line 152 of the outlet portion 112. Such an arrangement is that in the gas meter, the positions of the inlet 111 and the outlet 112 are determined, and the center line 151 in the left-right direction of the element unit is matched with the center line 152 of the outlet 112. This is due to the fact that the arrangement of the element portion increases the outer shape of the fluidic flow meter, which may hinder installation as a gas meter.

However, as described above, if the center line 151 of the element portion in the left-right direction does not coincide with the center line 152 of the outlet portion 112, despite the fact that the shape of the element portion is bilaterally symmetric, the discharge path The flow path going to the outlet 112 through 131 and the flow path going to the outlet 112 through the discharge path 132 are asymmetric. That is, the resistance of the flow path toward the outlet 112 through the discharge path 131 is greater than the resistance of the flow path toward the outlet 112 through the discharge path 132. Therefore, especially when the flow rate is large, the feedback flow path 1
There is a problem in that the flow of the gas differs between 27 and 128, and the waveform of the fluidic oscillation becomes unstable, making it impossible to measure the flow rate accurately.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to stabilize fluidic oscillation in a fluidic flow meter having an asymmetric discharge flow path from an element portion to an outlet portion, particularly at a large flow rate. Another object of the present invention is to provide a fluidic flowmeter capable of performing accurate flow measurement.

[0008]

According to a first aspect of the present invention, there is provided a fluidic flow meter having an inlet for receiving a fluid, a nozzle for generating a jet by passing the fluid received from the inlet, and a downstream side of the nozzle. A pair of side walls that form an enlarged flow path, and a pair of side walls that are provided outside the pair of side walls and return the fluid that has passed through the nozzle to the nozzle outlet side along the outside of each side wall. A return guide forming a feedback channel, and an outlet for discharging fluid, the outlet being disposed at a position where the center line does not coincide with the center line of the nozzle, and flowing along each side wall through the nozzle a discharge passage for guiding the fluid to the outlet, before
The fluid flowing along each side wall after passing through the nozzle is
Outlet to the outside of the
Indicates that the resistance of the discharge passage is on both sides of the center line of the nozzle.
So that it is equalized by the center line of the nozzle
The area closer to the outlet is larger than the area farther from the outlet
And a detecting means for detecting a change in the direction of flow of the fluid passing through the nozzle.

In this fluidic flow meter, the fluid received from the inlet passes through the nozzle to form a jet.
The fluid that has passed through the nozzle flows alternately through a pair of feedback flow paths, and is discharged from an outlet through a discharge flow path.
In the discharge flow path, the resistance of the flow path is equalized on both sides of the center line of the nozzle, so that the flow of the fluid in the pair of feedback flow paths is equalized, and the fluidic oscillation is stabilized.

[0010] The fluidic flow meter according to claim 2 is
Inlet for receiving fluid and received from this inlet
A nozzle that generates a jet by passing fluid, and this nozzle
Pair that is provided downstream of the
A side wall, and the nose provided outside the pair of side walls.
Fluid passing through the nozzle along the outside of each side wall
Form a pair of feedback channels to return to the jet port side
Return guide and the outlet for discharging fluid.
Position where the center line does not match the center line of the nozzle
Outlets, and each side wall passing through the nozzle.
Discharge channel for guiding the fluid flowing to the outlet portion,
The fluid flowing along each side wall passing through the nozzle is
Including a discharge port to discharge outside the turn guide, a discharge flow path
Resistance is equalized on both sides of the center line of the nozzle
So that the side wall and the hole near the discharge port are
The distance between the turn guide and the center line of the nozzle
The nearer to the outlet is smaller than the farther to the outlet
The formed discharge channel and the flow of fluid that has passed through the nozzle
Detection means for detecting a change in direction
It is.

[0011] In this fluidic flow meter, the inlet
The fluid received from the nozzle passes through the nozzle to form a jet.
The fluid that has passed through this nozzle passes through a pair of feedback channels.
Flows alternately, and is discharged from the outlet through the discharge flow path.
The discharge passage has a flow path resistance on both sides of the center line of the nozzle.
Equalized, so that a pair of feedback channels
Fluid flow is equalized and fluidic oscillation
Becomes stable .

[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 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. This return guide 29
It extends continuously from the downstream side of the target 26 to the ejection port side of the nozzle 21 so as to surround the side walls 23 and 24.

The return guide 29 includes a side wall 2.
Discharge ports 35 and 36 for discharging gas flowing through the nozzle 21 and flowing along the respective side walls 23 and 24 to the outside of the return guide 29 are provided at positions outside the nozzles 3 and 24, respectively. A pair of discharge paths 31 and 32 are formed between the discharge ports 35 and 36 and the outlet 12 by the back surface of the return guide 29 and the main body 10. In addition,
The discharge flow path that guides the gas passing through the nozzle 21 and flowing along each of the side walls 23 and 24 to the outlet portion 12 includes these discharge ports 35 and
36 and discharge paths 31 and 32.

In the present embodiment, the center line 51 of the nozzle 21 (the center line in the left-right direction of the element section from the nozzle 21 to the front of the outlet 12) 51 does not coincide with the center line 52 of the outlet 12. Therefore, in the present embodiment, the discharge port 36 near the outlet 12 with the center line 51 of the nozzle 21 as a boundary is set so that the resistance of the discharge channel is equalized on both sides of the center line 51 of the nozzle 21. The cross-sectional area is formed smaller than the cross-sectional area of the discharge port 35 remote from the outlet 12. As a result, the outlet portion 12 passes through the discharge port 35 and the discharge path 31.
The resistance of the flow path toward the outlet and the flow path toward the outlet 12 through the discharge port 36 and the discharge path 32 are substantially equal.

Further, pressure guiding holes 33 and 34 are provided in the vicinity of the nozzle 21 of the nozzle 21. A differential pressure sensor 40 (not shown in FIG. 1) that detects a differential pressure by using a piezoelectric film or the like as a detection unit that detects a change in a direction in which gas flows through the nozzle 21 is provided outside the bottom of the main body 10. .) Is provided. The pressure guide holes 33 and 34 are connected to the respective pressure introduction ports of the differential pressure sensor 40. And
This pressure difference sensor 40 allows the pressure guiding hole 33 and the pressure guiding hole 34
Is detected, and a change in the direction in which the gas flows is detected based on a change in the differential pressure.

FIG. 2 is a block diagram showing the configuration of the circuit part of the fluidic flow meter of 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 40 and calculates the 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 calculation unit 41 generates a pulse by, for example, binarizing the output of the differential pressure sensor 40, counts the number of pulses per unit time, obtains a switching frequency of the direction in which the gas flowing through the nozzle 21 flows, This frequency is converted to a flow rate. Further, the fluidic flow meter of 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 a predetermined flow rate is detected for a predetermined time or more, the solenoid driving circuit 43 is operated to operate the solenoid 18, and the valve 17 opens the opening 16. And shut off the 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, the liquid is returned to the ejection port side of the nozzle 21, and a part is discharged from the outlet section 12 through the discharge port 35 and 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 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 a part thereof is discharged to the discharge port 3.
6 and is discharged from the outlet 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 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 switching frequency of the direction of flow of the gas passing through the nozzle 21 is obtained by the flow rate calculation unit 41 based on the output of the differential pressure sensor 40. The flow rate calculation unit 41 calculates the flow rate from the determined frequency and displays the flow rate on the display unit 42. Further, 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 flow rate calculation unit 41 operates the solenoid drive circuit 43 to operate the solenoid 18 and the valve 1.
The opening 16 is closed by 7 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 this embodiment, the center line 51 of the nozzle 21 and the center line 52 of the outlet 12 do not coincide with each other, but the discharge port closer to the outlet 12 with the center line 51 of the nozzle 21 as a boundary. 36 is formed smaller than the cross-sectional area of the outlet 35 remote from the outlet 12,
The resistance of the flow path going to the outlet 12 through the discharge port 35 and the discharge path 31 is substantially equal to the resistance of the flow path going to the outlet 12 through the discharge port 36 and the discharge path 32.
Therefore, the flow of gas in the pair of feedback channels 27 and 28 is equalized, and even when the flow rate is large, fluidic oscillation is stabilized, and accurate flow rate measurement is possible.

FIG. 3 is a sectional view showing a configuration of a fluidic flow meter according to a second embodiment of the present invention. As shown in this figure, in the present embodiment, discharge ports 35 and 36 are provided for the return guide 29 in the fluidic flow meter of the first embodiment.
In addition, a discharge port 37 is further provided at a position opposite to the nozzle of the second target 26. This outlet 37 is
The cross-sectional area of the portion closer to the outlet portion 12 with respect to the center line 51 of the nozzle 21 is determined by the cross-sectional area of the outlet portion 12 so that the resistance of the discharge passage is equalized on both sides of the center line 51 of the nozzle 21.
Is formed to be smaller than the cross-sectional area of the portion farther away from.

In this fluidic flow meter, the side wall 23
The gas flowing along the discharge port 35 and the discharge path 31 or the resistance of the discharge flow path toward the outlet 12 through the discharge port 37, and the gas flowing along the side wall 24 is discharged through the discharge port 36 and the discharge path 32, or Outlet 1 through outlet 37
The resistance of the discharge flow path toward the second flow path 2 becomes substantially equal, and the flow of gas in the pair of feedback flow paths 27 and 28 is equalized.

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

FIG. 4 is a sectional view showing the configuration of a fluidic flow meter according to a third embodiment of the present invention. As shown in this figure, this embodiment differs from the fluidic flow meter of the second embodiment in that the cross-sectional areas of the outlets 35 and 36 are made equal, and the side wall 24 is made larger than the side wall 23 instead. Exit 36
Is smaller than the distance between the side wall 23 and the return guide 29 near the discharge port 35. Thereby, the resistance of the flow path going to the outlet 12 through the discharge port 35 and the discharge path 31 is substantially equal to the resistance of the flow path going to the outlet 12 through the discharge port 36 and the discharge path 32. .

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

It should be noted that the present invention is not limited to the above embodiments.
In order to equalize both sides of the discharge passage, a throttle may be provided in the middle of the discharge passage 32 closer to the outlet portion 12.

Instead of the differential pressure sensor 40, two pressure sensors connected to the pressure guiding holes 33 and 34 may be provided, and the flow rate may be calculated from the outputs of the two pressure sensors.

In each of the above embodiments, the fluidic flow meter for measuring the flow rate of a gas such as a gas has been described. Can also be used.

[0032]

As described above, according to the present invention, in a fluidic flow meter in which the discharge flow path from the element section to the outlet section is asymmetric, the resistance of the discharge flow path is equalized on both sides of the center line of the nozzle. Therefore, the flow of the fluid in the pair of feedback flow paths is equalized, and in particular, there is an effect that fluidic oscillation at a large flow rate is stabilized and accurate flow rate measurement can be performed.

[Brief description of the drawings]

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

FIG. 2 is a block diagram illustrating a configuration of a circuit portion of the fluidic flow meter according to the first embodiment of the present invention.

FIG. 3 is a sectional view illustrating a configuration of a fluidic flow meter according to a second embodiment of the present invention.

FIG. 4 is a sectional view illustrating a configuration of a fluidic flow meter according to a third embodiment of the present invention.

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

[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 31, 32 Discharge path 33, 34 Pressure guiding hole 35, 36 Discharge port 40 Differential pressure sensor

Claims (2)

(57) [Claims] 1. An inlet for receiving a fluid, a nozzle for generating a jet by passing the fluid received from the inlet, and a pair of side walls provided downstream of the nozzle and forming an enlarged flow path And a return guide provided outside the pair of side walls to form a pair of feedback channels for returning the fluid passing through the nozzle to the nozzle outlet side along the outside of each side wall, and discharging the fluid. An outlet part, the center line of which is located at a position that does not coincide with the center line of the nozzle, and a discharge passage that guides fluid flowing along each side wall through the nozzle to the outlet part. There, each side passing through the nozzle
Drain fluid flowing along the wall to the outside of the return guide
Outlet, where the resistance of the outlet flow path
Equalized on both sides of the center line of the nozzle
Closer to the outlet with the center line of the nozzle as the boundary
A discharge passage having a smaller cross-sectional area than that far from the outlet, and a detecting means for detecting a change in a direction of flow of the fluid passing through the nozzle. Fluidic flow meter. 2. An inlet for receiving a fluid, a nozzle for passing a fluid received from the inlet to generate a jet, and a pair of side walls provided downstream of the nozzle and forming an enlarged flow path And a return guide provided outside the pair of side walls to form a pair of feedback channels for returning the fluid passing through the nozzle to the nozzle outlet side along the outside of each side wall, and discharging the fluid. An outlet part, the center line of which is located at a position that does not coincide with the center line of the nozzle, and a discharge passage that guides fluid flowing along each side wall through the nozzle to the outlet part. There, each side passing through the nozzle
Drain fluid flowing along the wall to the outside of the return guide
Outlet, and the resistance of the discharge passage is within the nozzle
So that it is equalized on both sides of the conductor,
Distance between the Ritanga id and the side wall in the vicinity
But close to the outlet with the center line of the nozzle as a boundary
A fluid flow meter, comprising: a discharge channel formed to be smaller than a portion farther from the outlet portion; and detection means for detecting a change in a direction in which a fluid flows through the nozzle.