JPH0843155A - Fluidic flow meter - Google Patents

Abstract

(57) [Summary] [Purpose] To improve the accuracy of flow measurement by a fluidic flow meter. A flow sensor installation channel 9 is formed on the downstream side of a fluidic vibration generator 7 along a fluid flow direction, and the flow sensor 1 is installed in the flow sensor installation channel 9.
Install 5. The flow rate measurement when the flow rate of the fluid is large is performed by detecting the fluidic vibration generated in the fluidic vibration generating section 7 by the fluidic vibration detection sensor. This fluidic vibration is affected by the flow sensor 15. Since it is generated stably without being generated, the accuracy of flow rate measurement by the fluidic vibration detection sensor is improved.

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 measuring the flow rate of a fluid such as gas or liquid.

[0002]

2. Description of the Related Art In recent years, as a flow meter for measuring the flow rate of a fluid such as gas, a fluidic flow meter for measuring the flow rate of the fluid by detecting the vibration of the fluid (fluidic vibration) generated by the Coanda effect has been used. Development is in progress, and it is smaller than the conventional membrane gas meter,
In addition, it has an advantage that it has excellent durability because it has no moving parts.

In such a fluidic flowmeter, the fluidic flow is satisfactorily generated at a large flow rate of a predetermined flow rate or more, so that accurate flow rate measurement can be performed. Stable fluidic vibration does not occur at a small flow rate that is less than a predetermined amount,
It becomes impossible to measure the flow rate by detecting the fluidic vibration.

Therefore, there is a fluidic flowmeter which measures the flow rate by a flow sensor when the flow rate of the fluid is a small flow rate or less at a predetermined level.
The flow sensor is disclosed in Japanese Patent Laid-Open No. 921, Japanese Patent Application Laid-Open No. 4-326014, etc., and the flow sensor is installed in a jet nozzle unit that blows fluid toward a fluidic vibration generation unit that generates fluidic vibration.

On the other hand, as a fluidic flow meter used as a gas meter, a flow path from a gas inflow portion to a gas outflow portion is formed in a substantially U shape, and is first bent at about 90 °. A flow control valve is provided, and a fluidic vibration generator is provided on the downstream side of a second bent portion at about 90 °. A rectifying network or a rectifying plate for rectifying the flow of gas blown from the jet nozzle portion toward the fluidic vibration generating portion is provided on the upstream side of the jet nozzle portion along the gas flow direction. Japanese Patent Laid-Open No. 4-50724, Japanese Patent Laid-Open No. 4-5
No. 8112, Japanese Patent Application Laid-Open No. 4-160209, and the like.

[0006]

When a flow sensor is provided in the jet nozzle section, the flow sensor disturbs the flow of the fluid ejected from the jet nozzle section toward the fluidic vibration generating section, and the fluidic vibration generated is changed in flow rate. On the other hand, there is a drawback that the flow rate is not proportional and accurate flow rate measurement cannot be performed. Also, JP-A 1-3
As disclosed in Japanese Patent Publication No. 08921, when the flow sensor is provided above or below the jet nozzle unit, the flow sensor is located in the boundary layer of the flow, and accurate flow rate measurement is impossible. Becomes

Further, when the flow sensor is provided in the jet nozzle portion, the fluidic vibration detection sensor for detecting the fluidic vibration and the flow sensor are located very close to each other, which makes it difficult to install these sensors. Become.

[0008]

According to the first aspect of the present invention,
In a fluidic flow meter that measures the flow rate of a fluid at a large flow rate with a fluidic vibration detection sensor and the flow rate of a fluid at a small flow rate with a flow sensor, fluidic vibration occurs along the fluid flow direction. A flow sensor installation flow path was formed on the downstream side of the section, and the flow sensor was installed in this flow sensor installation flow path.

According to a second aspect of the present invention, in the first aspect of the present invention, a microbridge type heat is provided at the central portion in the width direction of the flow sensor installation flow passage and at a position of 1/4 to 3/4 in the height direction. A flow sensor was installed.

According to a third aspect of the present invention, in the first or second aspect of the invention, the fluidic vibration generator and the flow sensor installation flow channel are connected by a curved flow channel, and the curved flow channel is provided with the curved flow channel. A guide vane was provided to follow the curved state of the flow path.

According to a fourth aspect of the present invention, in the first or second aspect of the present invention, a flow passage shutoff valve is provided between the fluidic vibration generator and the flow sensor installation flow passage.

According to a fifth aspect of the invention, in the invention according to the fourth aspect, a rectifying member is provided between the flow passage cutoff valve and the flow sensor installation flow passage.

[0013]

According to the first aspect of the present invention, since the flow sensor is installed in the flow sensor installation flow passage formed on the downstream side of the fluidic vibration generator along the flow direction of the fluid, fluidic vibration is prevented. The flow of the fluid to be generated is not disturbed by the flow sensor, and fluidic vibration proportional to the flow rate is stably generated in the fluidic vibration generator. Furthermore, since the fluidic vibration detection sensor and the flow sensor are located separately,
It becomes easy to install these sensors.

According to the second aspect of the present invention, since the flow sensor is located away from the wall surface of the flow sensor installation flow path, the flow sensor is affected by the boundary layer developed near the wall surface when the fluid flows. Therefore, accurate flow rate measurement can be performed.

According to the third aspect of the present invention, the fluid flowing in the curved flow passage and flowing into the flow sensor installation flow passage is guided by the guide vanes to prevent the drift. Therefore, the flow rate can be accurately measured by the flow sensor.

According to the fourth aspect of the present invention, since the flow path cutoff valve is provided on the downstream side of the fluidic vibration generating section along the fluid flow direction, the flow of the fluid can be prevented by providing the flow path cutoff valve. Even if disturbed, it does not have any adverse effect on the occurrence of fluidic vibration.

According to the fifth aspect of the present invention, by providing the flow path shutoff valve, even if the flow of fluid on the upstream side of the flow sensor installation flow path is disturbed, the fluid flowing into the flow sensor installation flow path is Since it is rectified by the rectifying member, it is possible to accurately measure the flow rate by the flow sensor.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to FIGS. The present embodiment corresponds to the invention described in claim 1 or 2. FIG. 2 is an exploded perspective view showing the entire structure of a fluidic flow meter used in a gas meter to measure the amount of gas used (flow rate). It is formed by fixing the lid portion 2 and the bottom plate 3 in a state of sandwiching. Further, FIG. 1 is a plan view showing a state in which an inflow pipe 4 and a discharge pipe 5 to which a gas pipe (not shown) is connected are attached to the housing 1, and a lid portion 2 is removed.

Here, in the casing 1, a set ring space 6 for rectifying the flow of gas flowing from the inflow pipe 4, a fluidic vibration generator 7 for generating fluidic vibration, and the set ring space. A jet nozzle 8 for blowing the gas rectified in 6 toward the fluidic vibration generator 7, and a flow sensor installation flow path located downstream of the fluidic vibration generator 7 in the gas flow direction. 9 is formed. In addition,
The fluidic vibration generating section 7 includes a flow channel expanding section 10 communicating with the set ring space 6 via the jet nozzle section 8, a pendulum 11 and an end block 12 disposed in the flow channel expanding section 10, It is formed by the inner peripheral wall 13 of the flow channel expanding portion 10.

The fluidic flowmeter has a fluidic vibration detection sensor (not shown) for detecting the fluidic vibration generated in the fluidic vibration generator 7 and measuring the gas flow rate based on the detection result. Is provided. In this fluidic vibration detection sensor, pressure fluctuations due to fluidic vibration are introduced from a pair of pressure extraction holes 14 formed at the one end of the lid portion 2 and opening at the flow passage enlarging portion 10.

Next, in the fluidic flowmeter,
A microbridge thermal flow sensor 15 is provided for measuring the flow rate of the flowing gas when stable fluidic oscillation does not occur because the flow rate of the gas is a small flow rate of a predetermined amount or less. The bridge circuit portion 15a of the flow sensor 15 has a thin substrate 1
5b, and the bridge circuit portion 15a is provided at the central portion of the flow sensor installation flow channel 9 in the width direction (arrow a direction) and the position of 1/4 to 3/4 in the height direction (arrow b direction). is set up.

In such a structure, the gas flowing from the inflow pipe 4 into the set ring space 6 is rectified in the set ring space 6 and then blown out from the jet nozzle portion 8 into the flow passage expanding portion 10. When the flow rate of the gas at this time is a large flow rate (100 liters / hour to 3000 liters / hour) of a predetermined amount or more, fluidic vibration having a frequency proportional to the flow rate of the gas is generated. By detecting the frequency of fluidic vibration with a fluidic vibration detection sensor, the flow rate of gas can be measured based on the detection result.

Next, when the flow rate of the gas is a small flow rate (3 to 200 liters / hour) of a predetermined amount or less, stable fluidic vibration does not occur (note that almost no fluidic vibration occurs). It is difficult to measure the gas flow rate by the fluidic vibration detection sensor. Therefore, when the flow rate of the gas is small below the set value, the flow sensor 15 is switched to measure the flow rate.

Here, the flow sensor installation flow path 9 is formed on the downstream side of the fluidic vibration generating section 7 along the gas flow direction, and the bridge circuit of the flow sensor 15 is provided in the flow sensor installation flow path 9. Since the portion 15a is provided, the flow sensor 15 does not disturb the flow of gas blown from the jet nozzle portion 8 toward the fluidic vibration generating portion 7. Therefore, despite the fluidic flowmeter provided with the flow sensor 15,
In the fluidic vibration generator 7, fluidic vibration proportional to the gas flow rate is stably generated, and the gas flow rate can be measured with high accuracy by the fluidic vibration detection sensor.

Further, since the fluidic vibration detection sensor and the flow sensor 15 are located apart from each other, the fluidic vibration detection sensor and the flow sensor 15 can be easily installed. In particular, since the sensor body (not shown) of the fluidic vibration detection sensor and the sensor body 15c of the flow sensor 15 are separated from each other, the sensor body 15c can be easily fixed to the upper surface side of the lid 2. You will be able to do it.

Further, since the bridge circuit portion 15a is located away from the wall surface of the flow sensor installation flow path 9, the bridge circuit portion 15a has a wall surface when gas flows in the flow sensor installation flow path 9. Unaffected by nearby boundary layers. Therefore, even when the flow rate of the gas is measured by the flow sensor 15, the flow rate can be measured with high accuracy.

FIG. 4 shows the velocity distribution in the height direction of the flow sensor installation channel 9 measured using a platinum anemometer. As is clear from this result, the flow sensor 15 may be provided within the range of 1/4 to 3/4 in the height direction. Further, in FIG. 3, the substrate 15b of the flow sensor 15 reaches the bottom of the flow sensor installation flow path 9, but it is better that the flow path of the fluid is shorter, particularly, the flow path ceiling (or the flow path bottom surface). ) Is preferably projected to a height of 1/4 to 1/2.

Next, a second embodiment of the present invention will be described with reference to FIG. The same parts as those described with reference to FIGS. 1 to 4 are designated by the same reference numerals, and description thereof will be omitted (same below). This embodiment corresponds to the invention described in claim 3, in which the inflow pipe 4 and the exhaust pipe 5 are formed in the same direction, and the fluidic vibration generator 7 and the flow sensor installation flow path 9 are provided. Are connected by a curved flow path 16 curved in a substantially U shape. In the curved flow path 16, the guide vanes 17, 18 following the curved state of the curved flow path 16 are formed.
Is provided.

In such a structure, when the flow rate of the gas is a large flow rate of a predetermined amount or more, the flow rate of the gas is measured by the fluidic vibration detection sensor. On the other hand, when the flow rate of the gas is a small flow rate equal to or less than the predetermined amount, the flow sensor 15 measures the flow rate.

Here, when the flow sensor 15 is used to measure the flow rate, the gas flowing in the curved flow path 16 and flowing into the flow sensor installation flow path 9 is a guide vane 17, 1.
Guided by 8 prevents drift.
Therefore, since the gas flowing in the flow sensor installation flow path 9 flows in the flow sensor installation flow path 9 without causing a non-uniform flow, the flow sensor 15 can accurately measure the flow rate.

Next, a third embodiment of the present invention will be described with reference to FIG. This embodiment corresponds to the invention described in claim 4, in which the inflow pipe 4 and the discharge pipe 5 are formed in the same direction as in the second embodiment described above, and are also described above. Similar to the second embodiment, the fluidic vibration generator 7 and the flow sensor installation flow channel 9 are connected by a curved flow channel 16 that is curved in a substantially U shape.

A guide vane 17 is provided in the curved portion 16 at the first curved portion at about 90 ° similarly to the second embodiment described above, and at the second curved portion at about 90 °. A flow path cutoff valve 19 is provided in the.

In such a structure, the flow path shutoff valve 19
Is a fluidic vibration generator 7 along the gas flow direction
Since it is located on the downstream side of the flow channel, even if the flow path shutoff valve 19 is provided inside the fluidic flow meter, it does not have any adverse effect on the occurrence of fluidic vibration, and the gas flow rate is measured by the fluidic vibration detection sensor. Can be performed accurately.

Next, a fourth embodiment of the present invention will be described with reference to FIG. This embodiment corresponds to the invention described in claim 5, and as described in the above-mentioned fourth embodiment,
A flow path cutoff valve 19 is provided between the fluidic vibration generator 7 and the flow sensor installation flow path 9 along the gas flow direction, and the flow path cutoff valve 19 and the flow sensor installation flow path 9 are connected to each other. A rectifying net 20, which is a rectifying member, is provided between the two.

In such a structure, the flow path shutoff valve 19
Even if the gas flow on the upstream side of the flow sensor installation flow path 9 is disturbed by providing the above, the gas flowing into the flow sensor installation flow path 9 is rectified by the rectification network 20, so that the flow sensor 15 Flow rate can be measured accurately.

Next, a fifth embodiment of the present invention will be described with reference to FIG. This embodiment corresponds to the invention described in claim 5, and is provided with a honeycomb structure 21 as a rectifying member instead of the rectifying net 20 described in the above-mentioned fourth embodiment.

In this structure, in this embodiment, as in the above-described fourth embodiment, the gas flowing into the flow sensor installation channel 9 is rectified by the honeycomb structure 21 and the flow sensor 15 is used. Flow rate can be measured accurately.

[0038]

As described above, according to the invention of claim 1, the flow rate of the fluid at the large flow rate is measured by the fluidic vibration detection sensor, and the flow rate of the fluid at the small flow rate is measured by the flow sensor. In fluidic flow meters,
Since the flow sensor installation flow path is formed on the downstream side of the fluidic vibration generation unit along the flow direction of the fluid, and the flow sensor is installed in the flow sensor installation flow path,
It is possible to prevent the fluid flow that causes fluidic vibration from being disturbed by the flow sensor, and it is possible to generate stable fluidic vibration that is proportional to the flow rate. Nevertheless, the fluid flow rate can be accurately measured by the fluidic vibration detection sensor. Furthermore, since the fluidic vibration detection sensor and the flow sensor are located apart from each other, it is possible to easily install these sensors. It has the effect that it can be done.

As described above, the invention according to claim 2 is, in the invention according to claim 1, in the center portion in the width direction of the flow sensor installation flow path and at a position of 1/4 to 3/4 in the height direction. Since the micro bridge type thermal type flow sensor was installed,
The flow sensor will be located away from the wall surface of the flow sensor installation flow path, thus preventing the influence of the boundary layer developing near the wall surface on the flow sensor when the fluid flows in the flow sensor installation flow path. Therefore, there is an effect that the accuracy of flow rate measurement by the flow sensor can be improved.

As described above, the invention according to claim 3 is the invention according to claim 1 or 2, wherein the fluidic vibration generator and the flow sensor installation flow path are connected by a curved flow path. Since the guide vanes that follow the curved state of the curved flow path are provided inside, it is possible to prevent the flow of the fluid flowing in the curved flow path and flowing into the flow sensor installation flow path from becoming uneven by the guide vanes. You can and therefore
Despite the curved flow path on the upstream side of the flow sensor installation flow path, there is an effect that the accuracy of flow rate measurement by the flow sensor can be improved.

As described above, the invention according to claim 4 is characterized in that, in the invention according to claim 1 or 2, since the flow passage cutoff valve is provided between the fluidic vibration generating portion and the flow sensor installation flow passage, Even if the flow of the fluid is disturbed by providing the flow cutoff valve, it does not have any adverse effect on the occurrence of fluidic vibration.Therefore, the flow cutoff valve should be provided inside the fluidic flow meter. Despite this, there is an effect that the flow rate can be accurately measured based on the detection result of the fluidic vibration by the fluidic vibration detection sensor.

According to the invention of claim 5, as described above, in the invention of claim 4, since the rectifying member is provided between the flow path cutoff valve and the flow sensor installation flow path, the flow path cutoff valve is Even if the flow of fluid on the upstream side of the flow sensor installation flow path is disturbed by providing the flow sensor installation flow path, the fluid flowing into the flow sensor installation flow path can be rectified by the rectifying member. Despite the fact that the flow passage cutoff valve is provided on the upstream side of the passage, there is an effect that the accuracy of the flow rate measurement by the flow sensor can be improved.

[Brief description of drawings]

FIG. 1 is a plan view showing a state in which a lid portion is removed in a first embodiment of the present invention.

FIG. 2 is an exploded perspective view showing a state in which a housing and a lid are separated from each other.

FIG. 3 is a vertical sectional front view showing an installation position of a flow sensor.

FIG. 4 is a graph showing a flow velocity in a height direction in a flow channel.

FIG. 5 is a plan view showing a state in which a lid portion is removed in the second embodiment of the present invention.

FIG. 6 is a plan view showing a state in which a lid portion is removed in a third embodiment of the present invention.

FIG. 7 is an exploded perspective view showing a fourth embodiment of the present invention.

FIG. 8 is an exploded perspective view showing a fifth embodiment of the present invention.

[Explanation of symbols]

 7 Fluidic Vibration Generator 9 Flow Sensor Installation Flow Path 15 Flow Sensor 16 Curved Flow Path 17, 18 Guide Vane 19 Flow Cutoff Valve 20, 21 Rectifying Member

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Yuko Oshima Inc. 1-3-6 Nakamagome, Ota-ku, Tokyo Within Ricoh Co., Ltd. (72) Inventor Hiroyuki Horiguchi 1-3-3 Nakamagome, Ota-ku, Tokyo Stocks Company Ricoh

Claims (5)

[Claims] 1. A fluidic flow meter in which the flow rate of a fluid at a large flow rate is measured by a fluidic vibration detection sensor and the flow rate of a fluid at a small flow rate is measured by a flow sensor. A flow sensor for flow sensor installation is formed on the downstream side of the fluidic vibration generator, and the flow sensor is installed in the flow sensor installation flow path. 2. The micro-bridge type thermal type flow sensor is installed at a central portion in the width direction of the flow sensor installation flow passage and at a position of 1/4 to 3/4 in the height direction. The fluidic flow meter described in 1. 3. A fluidic vibration generating section and a flow sensor installation flow path are connected by a curved flow path, and a guide vane that follows the curved state of the curved flow path is provided in the curved flow path. The fluidic flowmeter according to claim 1 or 2. 4. The fluidic flow meter according to claim 1, further comprising a flow passage cutoff valve provided between the fluidic vibration generator and the flow sensor installation flow passage. 5. The fluidic flow meter according to claim 4, wherein a rectifying member is provided between the flow path cutoff valve and the flow sensor installation flow path.