JP3098935B2 - Wide range measurement 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 wide-range measurement type flow meter capable of accurately measuring a small flow rate to a large flow rate.

[0002]

2. Description of the Related Art For example, a fluid meter A as shown in FIG. The fluidic flow meter A includes a housing 1, a nozzle member 2 provided in the housing 1,
A target 3 and a pressure sensor 4 are provided.

The housing 1 has a rectangular parallelepiped space 1a, and is connected to another flow path via an inlet 1b and an outlet 1c. The nozzle member 2 is constituted by a pair of left-right symmetrical members, and is provided so as to occupy a downstream portion of the space 1a. For this reason, in the housing 1, an inflow space 1 d is formed upstream of the nozzle member 2. In addition, the nozzle member 2
The upstream portion forms a nozzle flow path 21 in parallel and close proximity, and a detection space 22 for detecting the flow rate is formed downstream of the nozzle flow path 21. Detection space 2
Reference numeral 2 denotes a structure including wall surfaces 22a and 22b which are symmetrically extended from the nozzle flow path 21 in an arc shape.

[0004] The target 3 is provided in the detection space 22 on an extension of the nozzle flow path 21. Further, the pressure sensor 4 is located in the detection space 22 and
And is provided on the left and right sides of the nozzle flow path 21, and detects the vibration of the jet fluid ejected from the nozzle flow path 21 by pressure.

The housing 1 is sealed by a cover (not shown). Therefore, the fluid that has flowed into the inflow port 1b flows into the inflow space 1d and the nozzle flow path 2d.
1, and flows out from the outlet 1c through the detection space 22.

In the fluidic flow meter A configured as described above, the flow of the ejected fluid flowing out of the nozzle flow path 21 periodically vibrates. That is, at a certain point, the ejected fluid flows along one side wall 3a of the target 3, partly rises along one wall surface 22a of the detection space 22, returns to the nozzle outlet, and the other passes through the outlet 1c. Outflow. At a certain point in time, the ejected fluid flows as if sucked to the other wall surface 3b of the target. Such ejection fluid vibrations occur periodically in the detection space 22.

Since there is a proportional relationship between the frequency of the ejected fluid oscillating in this way and the flow rate of the ejected fluid, the static pressure of the ejected fluid is detected by the pressure sensor 4 so that the fluid oscillation frequency is increased. And the flow rate of the fluid can be measured.

The flow characteristics of the above fluidic flow meter A are shown, for example, in FIG.
And FIG. In this experiment, the maximum measured flow rate Qma
The measurement was performed with a fluid flow meter A where x is 4 m ³ / h, and there is a linear relationship between the flow rate Q and the frequency F of the ejected fluid as shown in FIG.

When this relationship is expressed by a functional expression, the following expression (1) is obtained. Q = K · f (F) (1) Here, K is a constant determined by the physical properties of the fluid, the shape and size of the cross-sectional area of the nozzle flow path 21, and the like. Therefore, by measuring the frequency F of the ejected fluid, the flow rate Q
Can be requested. In particular, according to the experimental example of FIG.
The linearity between the flow rate Q and the frequency F of the ejected fluid is 0.2 m ³
/ H to ⁴ m ³ / h.

From the above experimental results, the fluidic flow meter A
When the error (instrument error) E is calculated as shown in FIG. However, the error (instrument error) E is calculated by the following equation (2).

E = {(Qcal−Q) / Qcal} × 100 [%] (2) Here, Q is a true value of the flow rate, and Qcal is a calculated value of the flow rate obtained from the equation (1).

The error (instrument error) E is, as shown in FIG.
If / Qmax is in the range of 0.05 to 1, it will be a small value within the test tolerance S. That is, the flow rate Q is 0.2 m ³ / h
If it is ４4 m ³ / h, the flow rate Q can be accurately measured.

However, when the flow rate Q is less than 0.2 m ³ / h, the oscillation of the ejected fluid becomes unstable.
, The linearity between the frequency F of the ejected fluid and the error (instrument error) E decreases. Therefore, the fluidic flow meter A is not suitable for measuring a small flow rate.

As another flow meter, there is, for example, a rectangular flow type flow meter B as shown in FIG. The rectangular flow path type flow meter B includes a housing 110 and a housing 11
0, the flow path forming member 120 provided in the housing 1
And a sub-housing 130 provided upstream of the sub-housing 10.

The housing 110 has a rectangular parallelepiped space 11.
0a, and is connected to the sub-housing 110 via the inlet 110b, and to another flow path via the outlet 110c. Channel forming member 120
Is composed of a pair of left-right symmetric
0a is provided so as to occupy the upstream portion. Therefore, the flow path forming member 120 is provided in the housing 110.
Outflow space 110d is configured on the downstream side of. Further, the flow path forming member 120 forms a rectangular flow path 121 having a rectangular cross section in which the upstream portion is parallel and close to each other.

The sub-housing 130 has a rectangular parallelepiped inflow space 130a.
The housing 110 is connected to an inlet 110b. The outlet 130c and the inlet 110b are continuously and smoothly formed from the inflow space 130a toward the rectangular channel 121. The sub-housing 130 has two inflow ports 130b formed in a direction orthogonal to the direction of the flow of the fluid in the rectangular flow path 121. Furthermore, in the inflow space 130a, the rectangular flow path 12
The cross-sectional area in the direction orthogonal to the direction of the flow of the fluid in 1 is formed equal to the cross-sectional area in the same direction in the outflow space 110d.

The sub-housing 130 has an inflow pressure sensor 1 for measuring a static pressure in the inflow space 130a.
40a is provided, and the housing 110 has an outflow space 1
Outflow pressure sensor 140 for measuring the static pressure within 10d
b is provided.

In the rectangular flow path type flow meter B configured as described above, the rectangular flow path 1
The difference between the static pressures on the upstream side and the downstream side of 21, that is, the constant pressure between the differential pressure ΔP of each pressure measured by the inflow pressure sensor 140 a and the outflow pressure sensor 140 b and the flow rate Q flowing through the rectangular channel 121. Have a relationship. An example of this relationship is shown in FIG. 6, which is shown as an experimental result of the example of the present invention. From this figure, it is understood that there is a linear relationship between the differential pressure ΔP and the flow rate Q. However, the flow rate Q
As the flow rate increases, there is an unstable transition region T where the fluid in the rectangular channel 121 shifts from laminar flow to turbulent flow, and the slope of the straight line changes from the transition region T as a boundary. .

Therefore, the rectangular flow meter B can accurately measure in the laminar flow region L where the flow of the fluid is stable and the inclination of the straight line is constant, that is, in the region where the flow rate is smaller than the transition region T. And measuring near the transition area T is not preferable in terms of accuracy. Therefore, the rectangular flow meter B is more suitable for measuring a small flow rate than for measuring a large flow rate.

[0019]

As described above, due to the measurement accuracy, the fluidic flow meter A is suitable for measuring a large flow rate, and the rectangular flow type flow meter B is suitable for measuring a small flow rate. You can see that.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem, and an object thereof is to provide a wide-range measurement type flow meter capable of accurately measuring a wide range of flow from a small flow to a large flow. It is in.

[0021]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a method for producing a jet fluid which is ejected from a nozzle flow path. And a fluidic flow meter that detects the flow rate of the ejected fluid because there is a proportional relationship between the two fluids, and a rectangular channel having a rectangular cross section formed by a gap between two opposing surfaces. A rectangular flow path type flow meter for measuring the flow rate of the fluid flowing through the same rectangular flow path from the differential pressure between the upstream side and the downstream side, and the fluidic flow meter and the rectangular flow path type flow meter are arranged in parallel. And a switching valve for switching the direction in which the fluid flows to at least one of a fluidic flow meter and a rectangular flow path type flow meter.

[0022]

In the present invention, when the flow rate is low, the flow rate is switched to a rectangular flow path type flow meter, and when the flow rate is high, the flow rate is switched to a fluidic flow meter. When the flow rate is small, the flow in the rectangular flow channel becomes a stable laminar flow in the rectangular flow channel type flow meter, and flows through the rectangular flow channel based on the differential pressure between the upstream and downstream sides of the rectangular flow channel. The flow rate of the fluid can be accurately measured. However, when the flow rate increases, the fluid flowing in the rectangular flow path transitions from laminar flow to turbulent flow. Therefore, the fluid flow meter is switched to a fluid flow meter before this transition. This switching can be easily performed by a switching valve.

In the fluidic flow meter, a large amount of fluid flows, so that the ejected fluid vibrates at a constant cycle. That is, the flow rate in the large flow rate area can be accurately measured.

Therefore, a wide range of flow rates from a small flow rate to a large flow rate can be accurately measured.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. Elements common to those of the conventional example shown in FIGS. 7 and 8 are denoted by the same reference numerals, and description thereof will be simplified. 4, 5, and 6 have already been described when showing the problems of the conventional example, and thus the description of the described portions will be omitted.

FIGS. 1 and 2 show a wide-range measurement type flow meter for measuring the flow rate of propane gas, in particular. This wide-range measurement type flow meter is configured to connect a fluidic flow meter A and a rectangular flow type flow meter B in parallel.

The fluidic flow meter A has an inlet 1b
A gas feeder 5 is provided at a position (1), and a first branch pipe 6a is connected to the gas feeder 5. The first branch pipe 6a is connected to the main pipe 151 via a three-way valve (switching valve) 150. Further, the main pipe 151 is connected to a gas cylinder 153 via a stop valve 152.

The gas feeder 5 includes a cover member 51 having a rectangular parallelepiped space 51 a continuous with the inlet 1 b of the housing 1.
Is fixed to the housing 1. Cover member 5
1 has a circular inlet 51 connected to the first branch pipe 6a.
a is formed at the center of the inflow port 51b.
A semi-cylindrical member 53 is provided so as to match 3a. The semi-cylindrical member 53 has a bottom surface 53b.
Is located right above the nozzle flow path 21 so as to prevent the gas flowing from the upstream from directly hitting the nozzle flow path 21. That is, the first branch pipe 6a
This prevents the dynamic pressure of the fluid flowing from above from directly acting on the nozzle flow path 21.

A guide member 54 is provided in the cover member 51 so as to face the left and right side surfaces 53c, 53c of the semi-cylindrical member 53. Each guide member 54 has a wall surface 54a extending from the inflow port 51b to each side surface 53c of the semi-cylindrical member 53. Each of the wall surfaces 54a, 54a and each of the side surfaces 53c, 53c constitutes a flow path that bisects the flow rate flowing from the first branch pipe 6a. Further, the first branch pipe 6a is formed in a cylindrical shape, and is connected to the inflow port 51b of the cover member 51 by means such as a screw or welding.

Further, at the outlet 1c of the housing 1,
The first delivery pipe 7a is connected, and the first delivery pipe 7a is connected to the main delivery pipe 154. Main delivery pipe 1
54 is connected to a gas supply destination via a stop valve 155.

The pressure sensor 4 is connected to a pressure detection circuit 8 as shown in FIG. The pressure detection circuit 8 is configured to convert the pressure fluctuation detected by the pressure sensor 4 into an electric signal. This pressure detection circuit 8 is further connected to a waveform shaping circuit 9.

The waveform shaping circuit 9 removes unnecessary signals such as noise from the signal converted into the voltage. The waveform shaping circuit 9 is further connected to a flow rate calculating circuit 11 through a frequency detecting circuit 10. The frequency detection circuit 10 detects the frequency from the voltage signal having the adjusted waveform.

The flow rate calculating circuit 11 is configured to calculate the flow rate flowing through the fluidic flow meter A from the relationship between the frequency F and the flow rate Q which are input in advance. The flow rate calculation circuit 11 is further connected to a flow rate display device 12. The flow rate display device 12 is capable of displaying the flow rate calculated by the flow rate calculation circuit 11 on a display every moment, and printing out the used flow rate, the integrated amount, and the like as necessary.

As shown in the experimental results of FIGS. 4 and 5, the fluidic flow meter A has a flow rate of 0.2 m ³ / h to ⁴ m ^3.
/ H can be accurately measured. As can be seen from FIG. 4, the maximum flow rate Qma
x can be expanded to about 5 m ³ / h.

On the other hand, in the rectangular flow path type flow meter B, a second branch pipe 6b is connected to each inlet 130b of the sub-housing 130, respectively. And each second branch pipe 6b
Are assembled into one third branch pipe 6c, and the third branch pipe 6c is connected to the three-way valve 150. Three-way valve 150
The main pipe 151 is connected to the first branch pipe 6a, the main pipe 151 is connected to the third branch pipe 6c, or the main pipe 151 is connected to the first branch pipe 6a and the third branch pipe 6c.
And the main pipe 151 and both branch pipes 6
a, 6c can be disconnected at the same time.

The outlet 110c of the housing 110
Is connected to a second delivery pipe 7b. The second delivery pipe 7b is connected to the main delivery pipe 15a together with the first delivery pipe 7a.
4.

As shown in FIG. 2, the inflow pressure sensor 140a and the outflow pressure sensor 140b
It is connected to the. The pressure detection circuit 161 detects the static pressure in the inflow space 130a from the output of the inflow pressure sensor 140a, and detects the static pressure in the outflow space 110d from the output of the outflow pressure sensor 140b.
The pressure detection circuit 161 further includes a flow rate calculation circuit 162
It is connected to the.

The flow rate calculating circuit 162 includes the pressure detecting circuit 16
The differential pressure ΔP of these static pressures is calculated from the static pressure in the inflow space 130a and the static pressure in the outflow space 110d output from 1 and the flow rate Q flowing through the rectangular channel 121 is calculated from the differential pressure ΔP.
Is calculated. That is, as shown in the experimental results of FIG.
Since there is a linear constant relationship between the pressure difference ΔP and the flow rate Q, the flow rate Q can be calculated from the pressure difference ΔP. The flow rate calculation circuit 162 is further connected to a flow rate display device 163.

The flow rate display device 163 is provided with a flow rate calculating circuit 16.
It is possible to display the flow rate calculated in 2 on a display every moment, and to print out the used flow rate, the integrated amount, and the like as necessary.

As shown in the experimental results of FIG. 6, the rectangular flow path type flow meter B has a size of about 0.01 m ³ smaller than the transition area T.
/ H to 0.2 m ³ / h. In this measurement range, the gas flowing in the rectangular flow path 121 is in a laminar flow state, and accurate measurement can be performed.

In FIG. 1, reference numeral 101 denotes a screw insertion hole for fixing a cover (not shown) to the housing 1; 102, a screw insertion hole for fixing the nozzle member 2 to the housing 1; 156 is a pressure gauge.

[0042] In broad measure flow meter constructed as described above, as shown in FIG. 3, when the flow rate of the measurement to the gas is in the range of 0.01m ³ /h~0.2m ³ / h is Measured with a rectangular flow path type flow meter B, 0.2 m ³ / h to 4 m
When it is in the range of ³ / h, the measurement is performed with the fluidic flow meter A. 0.01m ³ /h~0.2m ³ / when the flow rate as h is small, the rectangular channel flow meter B, rectangular channel 1
Since the flow in the flow path 21 is in a stable laminar flow state, the flow rate Q of the gas flowing through the rectangular flow path 121 can be accurately measured from the pressure difference ΔP between the upstream side and the downstream side of the rectangular flow path 121. . However, the flow rate Q becomes a little more than 0.2 m ³ / h, the gas flowing through the rectangular channel 121 is changed from laminar flow to turbulent flow, at a stage before the 0.2 m ³ / h of this transition Switch to fluidic flow meter A. This switching can be easily performed by the three-way valve 150.

In the fluidic flow meter A, 0.2 m ³
Since the gas having a large flow rate of / h to 4 m ³ / h flows, the flow of the gas ejected from the nozzle flow path 21 vibrates at a constant cycle. That is, the flow rate in the large flow rate area can be accurately measured.

Therefore, 0.01 m ³ / h to ⁴ m ³ / h
The flow rate in a wide range of h can be accurately measured. As can be seen from FIG. 4, the range that can be measured with fluidic is
Since possible to 0.2 to about 5 m ³ / h, as the whole flow range can be expanded up to 0.01 m ³ / h to about 5 m ³ / h.

Further, by switching the three-way valve 150 so that the gas flows to both the fluidic flow meter A and the rectangular flow type flow meter B at the same time, it is possible to accurately measure a larger flow rate.

In the above embodiment, an example was shown in which propane gas was used as the fluid. However, this fluid is not limited to propane gas, but may be air or another gas.
Further, a liquid (Newtonian fluid) such as water or oil may be used.

Although the pressure detection circuits 8 and 161, the waveform shaping circuit 9, the frequency detection circuit 10, the flow rate calculation circuits 11 and 162, and the flow rate display devices 12 and 163 are separately configured, they are provided in one device. Is preferred. In that case, the pressure detection circuits 8 and 161 and the flow rate display device 1
It is preferable that the two and 163 are each configured by a common one, and are configured to switch the pressure sensor and the display content with the switching of the three-way valve 150.

Further, the three-way valve 150 may be constituted by an electromagnetic switching valve so as to be automatically switched to the fluidic flow meter A side or the rectangular flow path type flow meter B side. However, the point at which the rectangular flow meter B is switched to the fluidic flow meter A is slightly lower than 0.2 m ³ / h, and the point at which the fluidic flow meter A is switched to the rectangular flow meter B is 0. It should be slightly higher than 0.2 m ³ / h so that switching can be performed smoothly.

[0049]

According to the present invention, it is possible to easily switch to a rectangular flow meter when the flow rate is low and to switch to a fluidic flow meter when the flow rate is high. When the flow rate is small, an accurate flow rate can be measured by a rectangular flow path type flow meter, and when the flow rate is large, an accurate flow rate can be measured by a fluidic flow meter.

Therefore, a wide range of flow rate from a small flow rate to a large flow rate can be accurately measured.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part of a wide-range measurement type flow meter shown as one embodiment of the present invention.

FIG. 2 is a block diagram showing the wide range measurement type flow meter.

FIG. 3 is a diagram showing a shared range between a fluidic flow meter and a rectangular flow path type flow meter in the wide range measurement type flow meter.

FIG. 4 is a view showing experimental results of a fluidic flow meter in the wide range measurement type flow meter.

FIG. 5 is a diagram showing an error rate obtained from an experimental result of a fluidic flow meter in the wide range measurement type flow meter.

FIG. 6 is a view showing experimental results of a rectangular flow path type flow meter in the wide range measurement type flow meter.

FIG. 7 is a sectional view of a fluidic flow meter shown as a conventional example.

FIG. 8 is a sectional view of a rectangular flow path type flow meter shown as another conventional example.

[Explanation of symbols]

 A Fluidic flow meter B Rectangular flow path type flow meter 21 Nozzle flow path 121 Rectangular flow path 4 Pressure sensor 140a Inflow pressure sensor 140b Outflow pressure sensor 150 Switching valve (three-way valve) ΔP Differential pressure

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G01F 1/20 G01F 1/00 G01F 7/00

Claims (1)

(57) [Claims] 1. A periodic fluid vibration is generated in a jet fluid ejected from a nozzle flow path, and the flow rate of the ejected fluid is detected because a proportional relationship exists between the frequency of the periodic oscillation and the flow rate of the ejected fluid. Fluidic flow meter and two opposite
A rectangular channel having a rectangular channel having a rectangular cross section formed by a gap between surfaces, and measuring a flow rate of a fluid flowing through the rectangular channel from a differential pressure between an upstream side and a downstream side of the rectangular channel. A flowmeter, and the fluidic flowmeter and the rectangular flowmeter are connected in parallel, and the direction in which the fluid flows is switched to at least one of the fluidic flowmeter and the rectangular flowmeter. A wide-range measurement type flow meter having a switching valve.