JPH0545189A - Fluidic flowmeter - Google Patents

Abstract

PURPOSE:To widen an oscillation flow area and contrive the reduction of a space by providing an end block in a passage enlargement part from a deflection inducing element to a discharge pipe and make the end block unsymmetrical form to a center line. CONSTITUTION:A set ring space 3 for straightening a flow allowed to flow in from an inflow pipe into a two-dimensional flow, a passage reduction part 4 for straightening, a jet nozzle 5 and a passage enlargement part 6 are provided on a same line in order. A deflection inducing element 7 for causing a deflection current at the position opposed to the jet nozzle 5 in the passage enlargement part 6 is provided and an end block 9 for feedback having walls 9a, 9b at the position up to a discharge pipe 2 at the rear of a deflection inducing element 7 in the passenge enlargement part 6 is set. The set ring space 3, a discharge space 10 at the rear of the end block 9 up to the discharge pipe 2 and the end block 9 are made an unsymmetrical form to a straight line X connecting the jet nozzle 5 and the deflection inducing element 7. The one side of the passage of the oscillation caused by the feedback is lessened, the oscillation is promoted surely, a flow range is widened from a small flow to a large flow and the one side is made a little small, so the reduction of a space is contrived.

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 gas or liquid.

[0002]

2. Description of the Related Art A fluidic flowmeter utilizing fluidic oscillation, which has been developed as an alternative to a conventional membrane gas meter, is small in size and has no moving parts. Research and improvement are being carried out in various fields. Further, it is desired that the conventional gas flow meter requires a rising area for mounting and is small in view of urban aesthetics and does not matter in directionality in mounting. From this point of view, there is a demand for a small and high-performance fluidic flowmeter that takes advantage of its characteristics.

As described in general textbooks, the fluidic flowmeter pays attention to the fact that the flow acts to control itself, thereby causing vibration, and that the frequency is proportional to the flow rate. It was used. Such a fluidic flowmeter is disclosed in, for example, Japanese Patent Application Laid-Open No. 62-10811.
No. 5, JP-A-62-276411, JP-A-6
2-288520, JP-A-63-139214, JP-A-63-313018, JP-A 1-1
Although disclosed in Japanese Patent No. 24711, etc., its basic configuration and operation will be described with reference to FIG.

On the flow path connecting the inflow pipe 1 and the discharge pipe 2, a set ring space 3, a flow path contracting section 4, a jet nozzle 5 and a flow path expanding section 6 are provided in this order, and are introduced into the flow path expanding section 6. The pendulum 7, side blocks 8 and end blocks 9 are provided. Here, such a fluidic flowmeter has a line-symmetrical shape with respect to a straight line connecting the jet nozzle 5 and the exciter 7. End block 9
Has walls 9a, 9b extending toward the upstream side of the flow path so as to cover the side block 8 on both sides. Also,
Behind the end block 9 is a discharge space 10.

First, the tubular flow from the upstream side of the flow path is rectified into a two-dimensional flow in the set ring space 3 and further rectified by the flow path contracting section 4 to smoothly flow toward the jet nozzle 5. Then, the jet flow rectified by the jet nozzle 5 is divided into right and left by hitting the exciter 7, but in the space of the flow path expanding portion 6 up to the end block 9, when the flow exceeds a certain flow rate, the exciter 7 is discharged. Due to the instability of the vortex behind it, a left or right biased flow is formed. Therefore, the flow that hits the end block 9
Along the front of the end block 9 and side blocks 8
Along the circumference, it reaches the outlet of the jet nozzle 5 and hits the jet stream at right angles. Therefore, the direction of the jet flow is biased in the direction opposite to the initial drift by the flow returning from the side. This causes the same thing to happen again on the opposite side, with the result that the flow leaving the jet nozzle 5 changes direction in a regular and alternating manner. The frequency of this regular directional vibration increases linearly with increasing flow rate.

[0006]

However, in the case of such a fluidic flowmeter, although the frequency of vibration is almost proportional to the flow rate, its linearly changing range is 150 to 3000 per liter / hour. , For example, it is not within the range that can be used as a household gas meter. Moreover, the reduction of the pressure loss is insufficient. Furthermore, in all of the above-mentioned publications, etc., the inflow pipe 1 and the exhaust pipe 2 are arranged in line symmetry with respect to the center line, and there is room for improvement in size reduction in terms of occupied space. ,And,
There will also be restrictions on installation on the inflow side and the discharge side.

[0007]

According to a first aspect of the present invention, a set ring space for rectifying a flow flowing from an inflow pipe into a two-dimensional flow, a flow-flow reducing portion for rectification, a jet nozzle, Providing a flow path expansion part on the same line in order,
A pendulum that causes a biased flow is provided at a position facing the jet nozzle in the flow path expansion portion, and extends toward the upstream side of the flow path at a position behind the exciter in the flow path expansion portion up to the discharge pipe. Providing return end blocks having walls on both sides, the set ring space and the discharge space behind the end block leading to the discharge pipe and the end block with respect to the straight line connecting the jet nozzle and the exciter It was formed in an asymmetric shape.

In this case, according to the second aspect of the invention, the flow passage expanding portion is divided by a straight line connecting the jet nozzle and the exciter so that the ratio of the divided area is more than 1: 1 and less than 1: 5. An asymmetrical discharge space was formed.

According to the third aspect of the invention, at least one of the inflow pipe and the discharge pipe is arranged at a position other than the straight line connecting the jet nozzle and the exciter.

On the other hand, in the invention according to claim 4, the sensor for detecting the vibration of the flow caused by the jet flow from the jet nozzle by the change of the flow velocity or the pressure is provided in the flow path expanding portion from the jet nozzle to the exciter. The end block wall and the point on the inner wall of the flow passage enlarged portion that is continuous with the jet nozzle from the straight line connecting the center of the jet nozzle and the center of the exciter to the position double the width of the jet nozzle. Arranged in a region surrounded by each plane formed by a straight line connecting the point of the tip and a plane perpendicular to the straight line connecting the jet nozzle and the exciter through the face facing the jet nozzle of the exciter Let

Further, according to the invention of claim 5, a set ring space for rectifying a flow flowing in from the inflow pipe into a two-dimensional flow, a flow reducing portion for rectifying, a jet nozzle, and a flow passage expanding portion. Are sequentially provided on the same line, and an exciter that causes a biased flow is provided at a position facing the jet nozzle in the flow path expansion portion, and flow vibration caused by the jet flow from the jet nozzle is detected by a change in flow velocity or pressure. A sensor is provided, and a signal processing means for converting the frequency output from the sensor into a flow rate using a continuous function designated by at most five parameters is provided.

[0012]

According to the invention described in claim 1 or 2, the end block for returning the flow is provided in the flow passage expanding portion from the pendulum to the discharge pipe, and the flow passage is expanded without the side block. Since the inner wall of the portion is used as the return flow passage, it is possible to widen the vibration flow rate region. At this time, since the end block has an asymmetrical shape with respect to the center line, one side of the flow path of the vibration due to feedback can be made small, so that the flow rate range from small flow rate to large flow rate can be reliably promoted. Can be expanded. Also, since the flow oscillates in a two-dimensional space and changes linearly with respect to the flow rate, the set ring space and the discharge space behind the end block do not need to be symmetrical with respect to the center line. By forming the asymmetrical shape and making one smaller, space can be saved. Further, since it does not have a side block, the internal structure becomes simpler and the pressure loss can be reduced. Therefore, it can be used as a household gas meter or the like.

In this case, according to the third aspect of the invention, since at least one of the inflow pipe and the exhaust pipe is arranged at a position other than the straight line connecting the jet nozzle and the exciter, the mounting direction and place can be changed. It is possible to save space in any case.

Further, according to the invention of claim 4, since the flow rate sensor is installed in a predetermined area between the jet nozzle and the exciter, it is possible to detect a signal due to vibration at a high S / N ratio. Become.

Further, according to the fifth aspect of the invention, focusing on the relationship between the fluid output characteristic of the fluidic flowmeter and the flow rate, the frequency is converted into the flow rate by using a continuous function consisting of as few parameters as possible. Since this is done, highly accurate flow rate measurement is possible.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to FIGS. The same parts as those shown in FIG. 8 are designated by the same reference numerals. First, in a general fluidic flowmeter as shown in FIG. 8, experimentally examining the basic components such as the jet nozzle 5, the exciter 7, and the end block 9 for the principle of vibration, It was found that the flow-rectifying flow path reducing section 4, the jet nozzle 5, and the pendulum 7 that is the target of the flow play a large role, and further, the end block 9 plays a role of a return path.

Therefore, basically, in order to utilize the characteristics of the fluidic flowmeter, the structure is similar to the structure of the general fluidic flowmeter shown in FIG. 8, but in the present embodiment, As a structure for performing reliable vibration, a structure without the side block 8 is used, and the inner wall 6a of the flow path expanding portion 6 is used as a return flow path. Furthermore, when considered for the purpose of reducing the overall size, the space of the flow path enlarging portion 6 shows that the jet nozzle 5
It has been found that it is not necessary to have a symmetrical arrangement shape with respect to the straight line X connecting the center of the and the center of the exciter 7. This is the same for the inflow part, and the inflow pipe 1 is generally connected on the straight line X, but there is a slight set ring space 3 for making a tubular one into a two-dimensional flow. It suffices to arrange it symmetrically with respect to the straight line X, and it may be arranged at an arbitrary position indicated by an imaginary line in FIG. 1 from the inflow pipe 1 ′ to the inflow pipe 1 ″. The same applies to the discharge side, and the discharge pipe 2 is not limited to the symmetrical position indicated by the solid line, but may be arranged in an asymmetrical position as indicated by the discharge pipe 2 ', for example.

This embodiment is based on such a fact and is shown in FIG.
As shown in, the set ring space 3, the end block 9, and the discharge space 10 are asymmetrically arranged with respect to the straight line X. In comparison with FIG. 8, the right side (lower side of the straight line X) viewed from the jet nozzle 5 is asymmetrical, and in the illustrated example, a space of about 2/3 is obtained in order to obtain the same characteristics as the conventional one. It is suppressed, and it is said that the size will be about 1/2 when the space occupied by the connecting pipe portion is taken into consideration. Further, in the end block 9, the tip end of the wall 9a is largely extended toward the upstream side in correspondence with the asymmetrical shape, while the wall 9b side is slightly extended.

In the illustrated example, the ratio of the divided areas when the area expanding portion 6 is divided into two areas with the straight line X as the dividing line is set to 2: 1, but the ratio is not limited to this. It is desirable that the ratio be greater than 1: 1 and less than 5: 1. Further, in the illustrated example, the left side (upper side of the straight line X in the figure) viewed from the jet nozzle 5 is made asymmetrical, but the operation is the same regardless of whether the left side or the right side is increased.

FIG. 2 shows the measurement result of the relationship between the flow rate and the frequency as the measurement of the oscillation phenomenon by the fluidic flow meter having such a structure. That is, by reducing one side of the flow path of the vibration due to the return, the vibration is surely promoted even at a small flow rate, so that it is understood that the flow rate range is expanded from the small flow rate to the large flow rate. In this way, it is clear that the oscillating flow rate measurement area can be expanded and that the oscillating frequency changes linearly with increasing flow rate.

Further, according to this embodiment, since the side block 8 of the conventional system is not provided, the transition of the jet flow to the turbulent flow is delayed until the high flow rate region, and the motion of the jet flow can be directly detected. It becomes a thing and becomes efficient. Further, in order to surely vibrate, it is sufficient to use the inner wall 6a of the flow passage enlarging portion 6 as a return flow passage without the side block 8. Further, since the side block 8 is not required, the internal structure becomes simpler and the pressure loss is reduced.

Next, a second embodiment of the present invention will be described with reference to FIGS. In this embodiment, in the fluidic flowmeter structure as in the above embodiment, a sensor, for example, a hot-wire anemometer 11 that detects the vibration of the flow caused by the jet from the jet nozzle 5 by the change of the flow velocity or the pressure.
The arrangement of a and 11b, that is, the measurement area is devised.

First, the vibration waveform when the hot wire anemometer 11b is arranged and measured at the measuring point M1 of the narrower division by the straight line X in the flow path expanding portion 6 is shown by a solid line in FIG. A broken line in FIG. 4 shows a vibration waveform when 11 a is arranged at the measurement point M <b> 2 having a wider division by the straight line X in the flow path enlarging portion 6 and measured. Such a hot wire anemometer 11a, 1
FIG. 5 shows an example of measuring the frequency with respect to the change in the flow rate based on the output of 1b. By the way, the hot wire anemometers 11b, 1
When the vibration waveform is measured by placing 1a at the measurement points M3 and M4 behind the exciter 7, an output waveform as shown in FIG. 6 is obtained. According to the comparison between FIG. 6 and FIG. 4, when the hot-wire anemometers 11b and 11a are arranged like the measurement points M1 and M2, the hot-wire anemometers 11b and 11a due to the fluid vibration are arranged.
It can be seen that the signal waveforms from can be sampled at a high S / N ratio.
As a result, the measured flow rate range is from 65 liters / hour to 3
It is as wide as 500 liters / hour.

Here, the arrangement of the hot wire anemometers 11b and 11a is not limited to the points M1 and M2, but in the flow path expanding portion 6 from the jet nozzle 5 to the exciter 7 and to the jet nozzle 5. On the inner wall 6a of the continuous flow path expanding portion 6, straight lines connecting the points X1 and X2 at positions double the width of the jet nozzle and the points at the tips of the walls 9b and 9a of the end block 9 from the straight line X on both sides. Within a region surrounded by the respective planes formed by K1 and K2 and the plane N which passes through the face of the exciter 7 facing the jet nozzle 5 and is perpendicular to the straight line X,
Good measurement can be performed.

Further, a third embodiment of the present invention will be described with reference to FIG. First, the measurement points M1,
Hot wire anemometer 11 arranged in a predetermined area such as M2
The temporal behavior of the flow velocity signal due to b and 11a is as shown in FIG. 4, and the asymmetric fluidic flowmeter can detect a vibration signal that can be clearly separated, and its vibration frequency is as shown in FIG. It can be seen that it is roughly proportional to the flow rate. Therefore, it is possible to read the proportional relationship between the flow rate and the frequency from the relationship shown in FIG. 5, but it is understood that the two are not completely proportional in this figure as well. This is because the oscillating mechanism of the fluidic flowmeter is hydrodynamic, and therefore exhibits a nonlinear behavior that is one of the characteristics of fluid behavior, and the flow rate and frequency are not exactly proportional. Therefore, in order to use it as a measuring instrument, it is necessary to convert the fluidic oscillation frequency and the flow rate. In this respect,
In the simplest case, the experiment result as shown in FIG. 5 is used as a conversion table between the oscillation frequency and the flow rate, and the hot wire anemometer 11
With respect to the outputs of b and 11a, the signal processing unit may convert the frequency into the flow rate. However, according to this conversion table method, it is necessary to have a memory for storing a large amount of data, the data must be obtained by a large number of experiments, and it takes time to create a conversion table.

In view of the above point, the present embodiment studies the hydrodynamic characteristics of the fluidic flowmeter,
It enables highly accurate flow rate measurement with as few parameters as possible. First, according to the research results of the applicant,
It has been found that there is a relatively simple relationship between the fluidic oscillation and the flow rate, which is a continuous function that can be specified by at most 5 parameters. In particular, a polynomial of degree 4 or less, Q = a ₀ + a ₁ x + a ₂ X ² + a ₃ x ³ + a ₄ x ^4, is preferable. Here, Q and x are the flow rate and the frequency, respectively. Further, a _{0 to} a ₄ are parameters.

Actually, the effectiveness of the above relational expressions was examined for many fluidic meter shapes, but it was found that the above expressions can calculate highly accurate flow rates.
Furthermore, the AIC value was also the smallest before and after the cubic expression, confirming the validity of this relational expression.

This relational expression is used for the hot wire anemometers 11b and 11a.
It is processed by the microcomputer in the signal processing unit (signal processing means) 13 connected to the electrical connections 12b and 12a. The calculated flow rate is displayed or output as a signal to another device. Further, the parameters in the conversion function are calculated at the time of calibration of the fluidic flow meter and stored in the ROM in the signal processing unit 13. Since the parameters can be set at the time of calibration, it is possible to calibrate the flow meter with high accuracy using a small number of calibration points.

Although this embodiment is applied to the fluidic flowmeter of the asymmetrical structure according to the above-mentioned embodiment, the invention is not limited to this type of fluidic flowmeter and is similarly applied to the symmetrical structure. You can

[0030]

Since the present invention is configured as described above, according to the invention of claim 1 or 2, for returning the flow to the flow passage expanding portion from the pendulum to the discharge pipe. Since the end block is provided and the side wall is not used and the inner wall of the enlarged flow passage is used as the return flow passage, it is possible to widen the oscillating flow rate region. Since it has an asymmetrical shape, one side of the flow path of the vibration due to the return can be made small, so that the flow range can be widened from a small flow to a large flow because the vibration is surely promoted, and the flow is 2 Since it is sufficient to vibrate in a three-dimensional space and change linearly with respect to the flow rate, the settling space and the discharge space behind the end block do not have to be symmetric with respect to the center line of the flow. By forming it into a nominal shape and making one smaller, space can be saved, and since there is no side block, the internal structure becomes simpler and the pressure loss can be reduced. It can be used as a household gas meter.

In this case, according to the third aspect of the invention, since at least one of the inflow pipe and the exhaust pipe is arranged at a position other than the straight line connecting the jet nozzle and the exciter, the mounting direction and place can be changed. Space saving can be achieved regardless.

Further, according to the invention of claim 4, since the flow rate sensor is installed in a predetermined region between the jet nozzle and the exciter, it is possible to detect a signal due to vibration at a high S / N ratio.

Further, according to the fifth aspect of the invention, focusing on the relationship between the fluid output characteristic of the fluidic flowmeter and the flow rate, the frequency is converted into the flow rate using a continuous function consisting of as few parameters as possible. Since this is done, highly accurate flow rate measurement is possible.

[Brief description of drawings]

FIG. 1 is a horizontal sectional view showing a first embodiment of the present invention.

FIG. 2 is a characteristic diagram showing a flow rate-frequency characteristic.

FIG. 3 is a horizontal sectional view showing a second embodiment of the present invention.

FIG. 4 is a characteristic diagram showing a temporal behavior of a flow velocity signal when measured in a predetermined region.

FIG. 5 is a characteristic diagram showing flow rate-frequency characteristics.

FIG. 6 is a characteristic diagram showing a temporal behavior of a flow velocity signal when measured outside a predetermined region.

FIG. 7 is a horizontal sectional view showing a third embodiment of the present invention.

FIG. 8 is a horizontal sectional view showing a general fluidic flow meter structure.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Inflow pipe 2 Exhaust pipe 3 Settling space 4 Flow path reducing part 5 Jet nozzle 6 Flow path expanding part 7 Pendulum 9 End block 9a, 9b Wall 10 Exhaust space 11a, 11b Sensor 13 Signal processing means X Straight line

Front Page Continuation (72) Inventor Kenji Okada 1-3-6 Nakamagome, Ota-ku, Tokyo Within Ricoh Co., Ltd. (72) Inventor Yoshio Watanabe 1-3-6 Nakamagome, Ota-ku, Tokyo Within Ricoh Co., Ltd. (72) Inventor Masafumi Kamonaga 1-3-6 Nakamagome, Ota-ku, Tokyo Within Ricoh Co., Ltd. (72) Inventor Junichi Takahashi 1-3-6 Nakamagome, Ota-ku, Tokyo Within Ricoh Co., Ltd. (72) Inventor Hisakage Kondo, Ricoh Elemex Co., Ltd., 2-8-24 Izumi 2-chome, Higashi-ku, Nagoya, Aichi (72) Inventor Toshiyuki Takamiya 6-16-10 Minamioi, Shinagawa-ku, Tokyo Ricoh Seiki Co., Ltd.

Claims (5)

[Claims] 1. A set ring space for rectifying a flow that flows in from an inflow pipe into a two-dimensional flow, a rectifying flow passage reducing portion, a jet nozzle, and a flow passage expanding portion are sequentially provided on the same line, A pendulum that causes a biased flow is provided at a position facing the jet nozzle in the flow path expansion portion, and extends toward the upstream side of the flow path at a position behind the exciter in the flow path expansion portion up to the discharge pipe. Providing return end blocks having walls on both sides, the set ring space and the discharge space behind the end block leading to the discharge pipe and the end block with respect to the straight line connecting the jet nozzle and the exciter A fluidic flowmeter characterized by having an asymmetrical shape. 2. The asymmetrical discharge space is formed by dividing the flow path expanding portion by a straight line connecting the jet nozzle and the exciter so that the ratio of the divided regions is greater than 1: 1 and less than 1: 5. The fluidic flowmeter according to claim 1, which is characterized in that. 3. The fluidic flowmeter according to claim 1, wherein at least one of the inflow pipe and the discharge pipe is arranged at a position other than a straight line connecting the jet nozzle and the exciter. 4. A sensor for detecting a vibration of a flow caused by a jet flow from a jet nozzle by a change in a flow velocity or a pressure is connected to the jet nozzle in a flow passage expanding portion from the jet nozzle to the exciter. A straight line connecting the center of the jet nozzle and the center of the exciter on the inner wall of the enlarged flow path is connected to the points at the position twice the width of the jet nozzle and the point at the end of the wall of the end block. It is arranged in a region surrounded by each plane formed by straight lines and a plane perpendicular to the straight line connecting the jet nozzle and the exciter through the face facing the jet nozzle of the exciter. A fluidic flowmeter according to item 1. 5. A set ring space for rectifying a flow flowing in from an inflow pipe into a two-dimensional flow, a rectifying flow passage reducing portion, a jet nozzle, and a flow passage expanding portion are sequentially provided on the same line, A pendulum that causes a biased flow is provided at a position facing the jet nozzle in the flow path expansion portion, and extends toward the upstream side of the flow path at a position behind the exciter in the flow path expansion portion up to the discharge pipe. A return end block having walls on both sides is provided, and a sensor for detecting the vibration of the flow caused by the jet from the jet nozzle is detected by the change of the flow velocity or the pressure. A fluidic flow meter characterized by comprising signal processing means for converting into a flow rate using a continuous function designated by a parameter.