JPH06323881A - Fluidic flowmeter - Google Patents

Abstract

PURPOSE:To facilitate the desposition of a flow sensor in a channel having highest current velocity distribution by securing a sensor board mounting the flow sensor to a fluidic element while sandwiching between sensor units. CONSTITUTION:A jet flow from a jet nozzle 5 flows into a fluidic element 10 and straightened through a settling space 3. The jet flow is deflected alternately and regularly through an oscillation inducer 7, an enlarged channel part 6, etc., and the frequency of deflection increases linearly as the flow rate increases. Such element 10 has a body which is the combination of a base member 10a and a cover member 10b having a rectangular hole 13 at the position corresponding to the space 3. On the other hand, a stripe sensor board 14 mounting a flow sensor 12 at a predetermined position on one side is sandwiched between sensor units 15a, 15b and tightened by means of screws 17 to be integrated. It is then inserted into the rectangular hole 13 and the board 14 and sensor 12 are located in the channel of the space 3 and secured to the member 10b by means of screws 16. This structure facilitates disposition of the sensor 12 at a position in the channel of the space 3 where the current velocity distribution is maximized.

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. The research and improvement are being promoted in the field. Further, it is desired that the conventional gas flow meter requires a rising area for installation and is small in size in view of urban aesthetics, regardless of directionality in installation. From this point of view, there is a demand for a compact and high-performance fluidic flowmeter that takes advantage of its features. As explained in general textbooks, the fluidic flow meter focuses on the fact that the flow acts to control itself, causing vibration, and utilizes the fact that the frequency is proportional to the flow rate. Is.

Here, in this type of fluidic flow meter, the flow exiting the jet nozzle does not regularly and alternately vibrate or the vibration itself does not occur in the low flow rate region. Therefore, the method of measuring the flow rate by measuring the fluidic vibration cannot be used, and the flow rate in the low flow rate range is measured by installing a flow sensor or the like in the jet nozzle or the like. As described above, the composite flowmeter in which the fluidic oscillation phenomenon in the high flow rate region is detected by the polymer piezoelectric film sensor to calculate the flow rate, and the flow rate is calculated in the low flow rate region is disclosed in JP-A-1-30892.
No. 1 publication and the like.

Regarding the mounting method of such a flow sensor, for example, a method of arranging the flow sensor above a jet nozzle as disclosed in Japanese Patent Laid-Open No. 1-308921 or a method disclosed in Japanese Patent Laid-Open No. 3-53125 is disclosed. In the nozzle side surface, a method in which a bypass flow path is provided as disclosed in Japanese Patent Laid-Open No. 3-53124, and a method in which the bypass flow path is provided in parallel with a fluidic element as disclosed in Japanese Patent Laid-Open No. 326019. A method of providing a flow channel and arranging the flow channel at the narrowed portion of the flow channel has been proposed.

[0005]

As described above, in the conventional composite flowmeter, the flow sensor for detecting the flow velocity in the flow rate region below a certain value is arranged on the upper surface, the bottom surface or the side surface of the jet nozzle. However, when it is installed in such a place, it is affected by the boundary layer that develops on the wall surface, and a sufficient output cannot be obtained particularly in a low flow rate region (for example, 3 to 30 liters / H). Further, when the flow sensor is arranged on the wall surface of the jet nozzle, three-dimensional turbulence is generated on the downstream side due to the shape of the convex portion, which adversely affects the fluidic vibration.

Further, it is not easy to assemble a flow sensor chip of about 2 mm square into a nozzle portion having a width of 3 to 4 mm, and there is a problem that the flow sensor chip is accidentally touched and damaged.

[0007]

According to a first aspect of the invention, a set ring space for rectifying a flow flowing in from an inflow pipe, a jet nozzle, and a flow passage expanding portion are sequentially provided on the same line, and the flow passage expanding portion is provided. Provided with an exciter that causes uneven flow on the extension of the center line at the position facing the jet nozzle inside, and an end block for return at the position behind the exciter in this enlarged flow path to the discharge pipe. A fluidic element provided, a flow sensor for measuring the flow rate when the flow rate is below a certain value, and a polymer piezoelectric film sensor for detecting the vibration phenomenon in the flow rate range in which the fluidic element vibrates sufficiently In the fluidic flow meter, a sensor unit is provided which is fixed to the fluidic element body by sandwiching the sensor substrate on which the flow sensor is mounted from both sides.

According to a second aspect of the present invention, a sensor substrate having a flow sensor mounted thereon and a set ring block that holds the sensor substrate and forms the set ring space are integrally fixed to the full Dick element body. A unit was set up.

[0009]

According to the first aspect of the present invention, since the sensor substrate on which the flow sensor is mounted is fixed to the fluidic element body by the sensor units that are held from both sides, the flow sensor is located at a position where the flow velocity distribution is maximum in the flow path. Can be easily arranged, and the flow can be two-dimensionally rectified by inserting the sensor substrate so as to divide the channel cross section of the set ring space into two.

Also in the invention described in claim 2, similarly,
Since the sensor substrate equipped with the flow sensor is fixed to the fluidic element body by the sensor unit, it becomes easy to place the flow sensor at the location where the flow velocity distribution is maximized in the flow path, and a settling space is formed. Since the set ring block is fixed to the body of the full-dic element together with the sensor substrate, there is no inconvenience that the flow sensor chip may be touched and damaged when assembled, and the assembling workability is improved.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the invention described in claim 1 will be described with reference to FIGS. First, the basic configuration and operation of the fluidic flow meter to which this embodiment is applied will be described with reference to FIG. 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 on a path connecting the inflow tube 1 and the exhaust tube 2, and a pendulum 7 is provided in the flow path expanding section 6. And an end block 8. Here, the shape is axisymmetric with respect to a straight line connecting the center of the jet nozzle 5 and the exciter 7. A discharge space 9 is formed behind the end block 8.

As a result, the flow flowing through the inflow pipe 1 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 be smoothly flown to the jet nozzle 5. Go to Then, the jet flow from the jet nozzle 5 is divided into left and right (upper and lower in the drawing) by hitting the pendulum 7, but the end block 8
In the space of the flow path expansion portion 6 up to the point, when the flow rate exceeds a certain flow rate, a flow biased to the left or the right is formed due to the instability of the vortex formed behind the exciter 7. Therefore, the flow that hits the end block 8 reaches the outlet of the jet nozzle 5 along the front surface of the end block 8 with the inner wall 6a of the flow path enlarging portion 6 as a return flow path, and hits the jet flow at a right angle. Therefore, the direction of the jet flow is biased in the direction opposite to the initial drift by the flow returning from that side. This again causes the same on the other side, with the result that the flow exiting the jet nozzle 5 changes direction of the flow in a regular and alternating manner. The frequency of this regular directional vibration increases linearly with increasing flow rate.

A fluidic flow meter 11 using such a fluidic element 10 has a flow sensor (described later) in a flow rate range in which the fluidic element 10 does not vibrate.
In the flow rate region in which the fluidic element 10 sufficiently vibrates by the fluid, the vibration phenomenon is generally detected by a pressure sensor, here a polymer piezoelectric film sensor (not shown), and the flow rate is detected. This is also the case in the present embodiment. Here, when such a fluidic flow meter 11 is used as a gas meter, the minimum measured flow rate required is 3 liters / H,
If the cross section of the settling space 3 is 5 mm × 20 mm, the flow velocity will be a very small value of about 1 cm / s. This is the average flow velocity calculated, and actually has a flow velocity distribution as shown in FIG. That is, in the case of the shape of the set ring space 3 as described above, the vertical direction (front and back direction in FIG. 3) has a velocity gradient up to about 20% in each of the upper and lower regions as shown in FIG. However, a stable distribution is shown in the other regions, while the lateral direction (vertical direction in FIG. 3) has a maximum in the central portion and decreases as it approaches the wall. Therefore, even if the flow rate is the same, the sensitivity of the flow sensor greatly depends on the installation location, so it can be said that it is desirable to install the flow sensor at the central portion in the vertical and horizontal directions.

In consideration of these points, the mounting method of the flow sensor 12 is devised as shown in FIGS. 1 and 2 in this embodiment. First, in the fluidic element 10 having the basic structure as described above, a combination of a base member 10a in which the flow path expanding portion 6 and the like are appropriately formed and a lid member 10b that covers the base member 10a is used as a fluidic element body. Square holes 13 are formed in the lid member 10b at positions corresponding to the set ring space 3. On the other hand, a small flow sensor 12 of about 2 mm square is mounted on a predetermined position on one side of a strip-shaped thin sensor substrate 14, and is disposed in the flow path in the set ring space 3 together with the sensor substrate 14 through the square hole 13. It is set so that it can be installed in the. A pair of sensor fixing blocks (sensor units) 15a and 15b for holding the sensor substrate 14 from both sides to position and fix the sensor substrate 14 and the flow sensor 12 are provided. These sensor fixing blocks 15a, 15b
Is an L-shaped member having a portion located on the lid member 10b and fixed to the lid member 10b by a screw 16.
A concave portion 15a ₁ for positioning the sensor substrate 14 is formed on the holding surface of one of the sensor fixing blocks 15a.

In this structure, the sensor substrate 14 is attached to the sensor fixing blocks 15a, 15 when assembling.
It is sandwiched by b, and the sensor fixing blocks 15a and 15b are fixed with screws 17 to be integrated (it may be integrated with an adhesive). Such a unit is used in the square hole 1 of the lid member 10b.
3, and the sensor substrate 14 and the flow sensor 12 are positioned in the flow path in the set ring space 3. In this state, the sensor fixing blocks 15a and 15b are fixed to the lid member 10b with the screws 16 (it may be fixed with an adhesive). At this time, depending on the size and positional relationship of each member, as shown in FIG. 2A, a position where the sensor substrate 14 divides the flow path into two on the center line in the direction perpendicular to the flow of the set ring space 3 is set. And, as shown in (b) of the figure, the center of the height direction, that is, the maximum position of the flow velocity. Further, as shown in FIG. 3B, the flow sensor 12 is set on the sensor substrate 14 at a position upstream (left side in the drawing) from the center line in the width direction. Finally, the joint between the sensor unit and the lid member 10b is filled with a sealing agent.

Therefore, according to the present embodiment, the sensor substrate 14 on which the flow sensor 12 is mounted is fixed to the main body by the sensor fixing blocks 15a and 15b which are held from both sides. It becomes easy to arrange the flow sensor 12 at a position where the flow velocity distribution is maximum. At the same time, by inserting the sensor substrate 12 so that the flow path cross section of the set ring space 3 is divided into two, it is possible to rectify the flow two-dimensionally.

Next, an embodiment of the invention described in claim 2 will be described with reference to FIG. The same parts as those shown in the above-mentioned embodiment are designated by the same reference numerals. In the present embodiment, a pair of set ring blocks 21a and 21b whose opposing wall surfaces are curved to form the set ring space 3 are provided separately from the base member 10a, and the set ring blocks 21a and 21b are used to form the flow sensor. The sensor substrate 14 on which the 12 is mounted is sandwiched, and the sensor unit 22 in which these are integrated is configured. For this reason,
The holding surface of the set ring block 21a is formed with a recess 21a ₁ for positioning the sensor substrate 14. A mounting portion 23 for mounting and fixing the sensor unit 22 is formed at a portion of the base member 10a corresponding to the set ring space 3. Further, the set ring blocks 21a and 21b are set so as to be integrally fixed by a screw or an adhesive.

The setting of the installation location of the flow sensor 12 or the sensor substrate 14 is the same as in the above embodiment.

In the case of this embodiment, the same effect as that of the above embodiment can be obtained. In particular, in the case of this embodiment, the set ring space 3 is connected to the set ring block 21a,
21b, and the set ring blocks 21a and 21b are fixed to the mounting portion 23 of the base member 10a integrally with the sensor substrate 14, so that the flow sensor 12 or the sensor substrate 1 can be assembled.
Since the work of inserting 2 into the set ring space 3 is eliminated and the work is carried in, there is no inconvenience of damaging the flow sensor chip, and the assembling workability is good.

The basic structure of the present invention is the fluidic flowmeter having the structure shown in FIG.
Not limited to the structure shown in FIG. 2, the direction of the inflow pipe 1 and the exhaust pipe 2, the mounting position, etc. may be appropriately changed. Further, although the illustrated example has a symmetrical structure with respect to the nozzle center line, the present invention is not limited to this, and an asymmetrical structure may be used.

[0021]

According to the first aspect of the present invention, in the composite fluidic flowmeter, a sensor unit is provided which is fixed to the fluidic element body by sandwiching a sensor substrate having a flow sensor from both sides. Therefore, it becomes easy to dispose the flow sensor at a position where the flow velocity distribution is maximized in the flow channel, and the flow rate can be reduced by inserting the sensor substrate so as to divide the flow channel cross section of the set ring space into two. It is also possible to rectify it dimensionally.

According to the second aspect of the present invention, a sensor substrate having a flow sensor mounted thereon and a set ring block that holds the sensor substrate and forms a set ring space are integrally fixed to the full Dick element body. Since the unit is provided, similarly, it becomes easy to place the flow sensor at the position where the flow velocity distribution is maximized in the flow path, and the set ring block that forms the set ring space is integrated with the sensor substrate to form a full-dic. Since the flow sensor chip is fixed to the element body, the flow sensor chip does not come into contact with and damage the wall surface of the set ring space when assembled, and the assembling workability is improved.

[Brief description of drawings]

FIG. 1 is an exploded perspective view showing an embodiment of the invention described in claim 1. FIG.

FIG. 2 shows the vicinity of the set ring space, (a)
Is a vertical sectional front view, and (b) is a vertical sectional side view.

FIG. 3 is a horizontal sectional view showing the basic structure of a fluidic flow meter.

FIG. 4 is a characteristic diagram showing velocity distributions in a vertical direction and a horizontal direction.

FIG. 5 is an exploded perspective view showing an embodiment of the invention described in claim 2.

[Explanation of symbols]

 1 Inflow pipe 2 Discharge pipe 3 Settling space 4 Flow path reducing part 5 Jet nozzle 6 Flow path expanding part 7 Pendulum 8 End block 10 Fluidic element 10a, 10b Fluidic element main body 11 Fluidic flow meter 12 Flow sensor 14 Sensor Substrate 15a, 15b Sensor unit 21a, 21b Set ring block 22 Sensor unit

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Toshiyuki Takamiya 6-16-10 Minamioi, Shinagawa-ku, Tokyo Ricoh Seiki Co., Ltd. (72) Inventor Shigeyuki Ito 2-28-24 Izumi, Higashi-ku, Nagoya, Aichi Prefecture Ricoh Elemex Co., Ltd.

Claims (2)

[Claims] 1. A set ring space for rectifying a flow flowing from an inflow pipe, a jet nozzle, and a flow passage expanding portion are sequentially provided on the same line, and a center line thereof is extended at a position facing the jet nozzle in the flow passage expanding portion. Provided with a pendulum that causes a biased flow on the line, and a fluidic element with an end block for feedback provided at a position behind the pendulum in the flow path expansion section up to the discharge pipe, and the flow rate is below a certain value. In a fluidic flowmeter having a flow sensor for performing flow rate measurement and a polymer piezoelectric film sensor that detects the vibration phenomenon in a flow rate region in which the fluidic element sufficiently vibrates fluidically, the flow sensor is mounted. A fluidic flowmeter comprising a sensor unit that is fixed to the fluidic element body by holding the sensor substrate from both sides. 2. A set ring space for rectifying a flow flowing from an inflow pipe, a jet nozzle, and a flow passage expanding portion are sequentially provided on the same line, and a center line thereof is extended at a position facing the jet nozzle in the flow passage expanding portion. Provided with a pendulum that causes a biased flow on the line, and a fluidic element with an end block for feedback provided at a position behind the pendulum in the flow path expansion section up to the discharge pipe, and the flow rate is below a certain value. In a fluidic flowmeter having a flow sensor for performing flow rate measurement and a polymer piezoelectric film sensor that detects the vibration phenomenon in a flow rate region in which the fluidic element sufficiently vibrates fluidically, the flow sensor is mounted. The sensor board and the set ring block that holds the sensor board and forms the set ring space are integrated to form the full-dic A fluidic flowmeter characterized by having a sensor unit fixed to the element body.