JPH04145327A - Fluidick flow meter - Google Patents

Abstract

PURPOSE:To miniaturize a flow meter by providing a piezoelectric film sensor at the bottom section of a passage main body, providing pressure wave guide ports on the cover body of the passage main body, and communicating them via a pressure signal transfer path constituted of groove sections provided on the cover body of the passage main body and through holes provided on side walls. CONSTITUTION:A flow sensor and a piezoelectric film sensor are provided at the bottom section of a passage main body 23 corresponding to a jet nozzle 32. A partition plate covering between the jet nozzle 32 and side walls 34a, 34b is provided inside a cover body 25. Pressure wave guide ports 49 are bored at the optimum extraction position of the alternating pressure wave generated near the outlet of the jet nozzle 32 on the partition plate, and vent holes are bored at the portions faced to through holes 47 bored on the side walls 34a, 34b. Groove sections 51 are provided on the cover body 25, and they communicate the pressure wave guide ports 49 and the vent holes and constitute a pressure signal transfer path. The flow sensor and the piezoelectric film sensor can be provided in parallel on the same side face of the passage main body 23 by the pressure signal transfer path.

Description

Detailed Description of the Invention [Objective of the Invention] (Industrial Field of Application) This invention detects alternating pressure waves caused by vibration phenomena of fluid such as gas ejected into a flow path from an ejection nozzle to determine the flow rate. Regarding fluidic flowmeters that detect

(Prior Art) Fluidic flowmeters installed in general households and the like to measure the flow rate of gas are known from, for example, Japanese Patent Application Laid-Open Nos. 63-313018 and 1-250725.

This fluidic flowmeter is provided with an ejection nozzle on the inlet side of a flow path, and when fluid is ejected from the ejection nozzle into the flow path, the ejected fluid flows, for example, along the right side wall due to the Coanda effect. A part of the fluid that flows to the right side wall becomes a return fluid, and the fluid energy of this return fluid is imparted to the ejected fluid, causing the ejected fluid to flow along the left side wall, which in turn flows to the left side wall. A part of the fluid becomes the return fluid, and the fluid energy of the return fluid is imparted to the ejected fluid, causing the ejected fluid to flow along the right side wall again.

That is, alternating pressure waves are generated by the vibration phenomenon of the fluid ejected from the ejection nozzle into the flow path. This alternating pressure wave is detected by a piezoelectric film sensor, and the flow rate is calculated from this frequency to detect the flow rate of the fluid.

By the way, in order to detect the alternating pressure waves, it is necessary to provide a pressure wave introducing section near the outlet of the jet nozzle at a position where the alternating pressure waves occur, but the position and interval of the pressure wave introducing section of the piezoelectric film sensor are as follows. Generally, the positions and intervals at which alternating pressure waves occur are different, and the two do not correspond. Furthermore, there are cases where the piezoelectric film sensor must be installed at a remote location because it is obstructed by other components. Therefore, in the past, pressure waves have been transmitted using the following method.

That is, in FIG. 5, the pressure wave introducing vibes 2, 2 are provided at intervals corresponding to the positions where alternating pressure waves are generated on the side wall of the channel body 1. On the other hand, a piezoelectric film sensor 3 is provided on the outer wall of the channel main body 1, and the pressure wave introduction parts 4, 4 provided on the piezoelectric film sensor 3 and the pressure wave introduction vibrators 2, 2 are connected to each other using a vibrator such as a vinyl tube. Connected by 5,5. Further, in FIG. 6, pressure wave introduction holes 6.6 are provided at intervals corresponding to positions where alternating pressure waves are generated on the side wall of the channel body 1.

On the other hand, a plate 8 is provided on the outer wall of the channel body 1 with a backing 7 interposed therebetween, and a piezoelectric film sensor 3 is provided on this plate 8 with a backing 9 interposed therebetween.

A through hole 10a is provided in the plate 8 and communicates with the pressure wave introducing portions 4, 4 provided in the piezoelectric film sensor 3.

10a, and through holes 10b, 10b communicating with the pressure wave introduction hole 6.degree.
0 is formed.

(Problem to be Solved by the Invention) However, as described above, in order to compensate for the difference between the interval between the pressure wave introduction parts of the piezoelectric film sensor and the position and interval at which alternating pressure waves are generated, a vibrator is connected to A device configured to transmit gas requires a space to connect the vibrator, making the flowmeter larger and requiring more connection points, leading to the risk of gas leakage. In addition, a plate is interposed,
This structure in which through holes are provided in the plate has the problem that the flowmeter becomes larger due to the thickness of the plate and the backing, and furthermore, processing and assembly are troublesome, leading to an increase in cost.

This invention was made in view of the above-mentioned circumstances, and its purpose is to form a pressure signal transmission path for transmitting pressure waves with a simple structure and to reduce the size of a flow meter. Our goal is to provide fluidic flowmeters that can

[Structure of the Invention] (Means and Effects for Solving the Problems) In order to achieve the above-mentioned object, the present invention provides a target in the flow path facing the jet nozzle, and also includes side walls on both sides with the target in between. In a fluidic flowmeter that detects the flow rate by detecting alternating pressure waves generated by the vibration phenomenon of the fluid ejected from the ejection nozzle using a piezoelectric film sensor, the flow path main body constituting the flow path The piezoelectric film sensor is provided at the bottom, and pressure wave inlets are provided at two locations where alternating pressure waves occur on the lid of the channel body, and these pressure wave inlets and the piezoelectric film sensor are connected to the lid of the channel body. This is achieved by communicating via a pressure signal transmission path consisting of a groove provided and a through hole provided in the side wall.

The alternating pressure waves generated by the vibration phenomenon of the fluid ejected from the ejection nozzle into the flow path are transmitted from the pressure wave inlet to the piezoelectric film sensor via a pressure signal transmission path consisting of a groove and a through hole. The flow rate is measured.

(Example) Hereinafter, one embodiment of the present invention will be described based on the drawings.

3 and 4 show the entire fluidic flowmeter, and 11 is a case. This case 11 is composed of a rectangular box-shaped case body 12 and a lid 13 that closes an opening of this case body 12. A gas inlet body 14 and a gas outlet body 15 are arranged side by side in the lower part of the case body 12, and a display window (not shown) is provided in the upper part.

A fluidic element 17 and a cutoff valve 18, which will be described later, are installed in the lower part of the inside of the case 11.

To explain the fluidic element 17, the first
It is constructed as shown in the figure and FIG. That is, 23 is a channel main body formed by die casting or the like, and a channel 26 is formed by closing the opening of the channel main body 23 with a lid 25 via a backing 24. The flow path 26 is divided by a partition wall 27, an upstream flow path 28 communicates with the gas inlet body 14, and a downstream flow path 29 communicates with the gas outlet body 15. A valve seat 30 is provided in the middle of the upstream flow path 28, and the valve body 31 of the cutoff valve 18 faces the valve seat 30. That is, when the pressure switch or seismic sensor (not shown) detects an abnormality, the shutoff valve 18 closes the flow path 26.
It is configured so that it can be blocked.

A jet nozzle 32 is provided on the partition wall 27 of the flow path main body 23 . This jet nozzle 32 has a slit shape that opens over the entire depth direction of the flow channel main body 23, and has protrusions 3 that project into the upstream flow channel 28 on both sides of the opening in the longitudinal direction.
2a and 32b, extending the nozzle passage length.

A first target 3 is provided in the downstream flow path 29 facing the jet nozzle 32 for stabilizing switching of the fluid flow direction.
3 is provided. Side walls 34 a and 34 b are symmetrically provided on both sides of the first target 33 . Furthermore, a second target 35 is provided in a central portion located on the downstream side of the first target 33,
Furthermore, a return wall 36 extending in the width direction of the downstream flow path 29 is provided on the downstream side. And the side wall 34
a.

Return passages 37a and 37b are formed on the outside of the return wall 34b, and a discharge passage 38a is formed on the outside of both ends of the return wall 36.

38b is provided.

Therefore, when fluid is ejected from the ejection nozzle 32 toward the downstream channel 29, the ejected fluid flows, for example, along the inside of the right side wall 34a due to the Coanda effect. Most of the fluid flowing into the right side wall 34a heads toward the discharge passage 38a, but a portion becomes return fluid and heads toward the return passage 37a. The fluid energy of this return fluid is imparted to the ejected fluid, and the ejected fluid begins to flow along the inside of the left side wall 34b. This time, a part of the fluid that has flowed to the left side wall 34b becomes the return fluid, and this return fluid flows along the inside of the left side wall 34b. The fluid energy of the fluid is imparted to the ejected fluid, causing the ejected fluid to flow again along the inside of the right side wall 34a. In other words,
It is configured so that alternating pressure waves are generated by the vibration phenomenon of the fluid ejected from the ejection nozzle 32 into the downstream flow path 29 .

Furthermore, the flow path main body 2 corresponding to the jet nozzle 32
A flow sensor 40 and a piezoelectric film sensor 41 are installed at the bottom of 3.
is provided. The flow sensor 40 includes a sensor body 4
2 and a sensor chip 43 equipped with a detection part consisting of a heat generating part and a temperature sensing part, the sensor main body 42 is fixed to the bottom of the channel main body 23, and the sensor chip 43 faces the jet nozzle 32. . That is, the flow sensor 40 is
In order to measure a small flow rate region, the flow path is narrowed and installed at a position where the flow velocity is the highest. The piezoelectric film sensor 41 is for measuring a large flow rate region, and is composed of a sensor main body 44 and a pressure wave introducing section 45. The sensor main body 44 is fixed to the bottom of the flow channel main body 23, and the pressure wave The wave introduction section 45 communicates with a pressure signal transmission path 46, which will be described later.

That is, a through hole 47 is formed in the pair of side walls 34a, 34b in the longitudinal direction, one end of which opens to the pressure wave introducing section 45, and the other end of the side wall 34g, 34b.
It is open at the tip surface of b.

Furthermore, a partition plate 48 is provided between the inside of the lid 25 and the backing 24 to cover between the jet nozzle 32 and the side walls 34g and 34b. A pair of pressure wave introduction ports 49 and 49 are bored in the partition plate 48 near the exit of the jet nozzle 32 at optimal extraction positions for alternating pressure waves generated by vibration phenomena, and a pair of pressure wave inlets 49 and 49 are bored in the side wall 34.
a.

A through hole 5 is provided in a portion opposite to the through hole 47 drilled in 34b.
0.50 is drilled. Further, the lid body 25 that overlaps the partition plate 48 is provided with grooves 51.51 formed by press working or the like, and these grooves 51.51 communicate the pressure wave introduction port 49 and the through hole 50, A pressure signal transmission path 46 is configured that communicates the pressure wave introduction ports 49, 49 and the piezoelectric film sensor 41. That is, this pressure signal transmission path 46 forms a detour path for the pressure signal, and avoids overlapping the sensor body 44 of the piezoelectric film sensor 41 with the sensor body 42 of the flow sensor 40, and It is possible to arrange the flow sensor 40 and piezoelectric film sensor 41 in parallel.

On the other hand, in the upstream flow path 28, there is a flat first rectifying plate 52 made of a wire mesh and a mountain-shaped second rectifying plate 5 made of a wire mesh.
3 are installed, and these are provided so that they can be attached to and detached from the channel body 23.

Next, the operation of the fluidic flowmeter configured as described above will be explained. The fluid flowing in from the gas inlet body 14 passes through the upstream flow path 28 of the flow path 26, and further passes through the first flow path 28.
After being rectified by the rectifier plate 52 and the second rectifier plate 53, it heads toward the jet nozzle 32. Since the flow path of the jet nozzle 32 is narrowed, the flow velocity of the fluid increases, and the fluid is jetted from the jet nozzle 32 to the downstream flow path 29 . As the fluid passes through the jet nozzle 32, its flow rate is detected by the flow sensor 40. When fluid is ejected from the ejection nozzle 32 toward the downstream channel 29, the ejected fluid flows, for example, along the inside of the right side wall 34a due to the Coanda effect. Most of the fluid flowing to the right side wall 34a heads toward the discharge passage 38g, but a portion becomes return fluid and heads toward the return passage 37a. The fluid energy of this return fluid is imparted to the ejected fluid, and the ejected fluid is transferred to the left side wall 34.
A part of the fluid that has flowed to the left side wall 34b becomes a return fluid, and the fluid energy of this return fluid is imparted to the ejected fluid, and the ejected fluid returns to the right side wall 34a. It starts to flow along the inside of the . That is, an alternating pressure wave is generated by the vibration phenomenon of the fluid ejected from the ejection nozzle 32 into the downstream flow path 29 .

This alternating pressure wave, that is, the pressure change caused by the change in the flow direction of the jet from the jet nozzle 32, is caused by the pressure wave introduction port 49,
49. Grooves 51, 51, through hole 50°50 and through hole 4
It is detected by the piezoelectric membrane sensor 41 via the pressure signal transmission path 46.46 consisting of 7.47.

The fluid flow rate is calculated from the frequency of the waveform signals from the flow sensor 40 and the piezoelectric film sensor 41 and displayed on the display window.

In addition, when assembling the flow sensor 40 and the piezoelectric film sensor 41 to the channel body 23,
Since the flow sensor 40 and the piezoelectric film sensor 41 are mounted on the same side surface from the same direction, assembly workability can be improved, and workability during maintenance inspection and repair can also be improved.

[Effects of the Invention] As explained above, according to the present invention, a pressure wave inlet is provided at the location 211i where alternating pressure waves occur on the lid body side of the flow channel main body constituting the flow channel, and a through hole is provided in the side wall. ,
Furthermore, since a groove is provided in the lid body to communicate the pressure wave inlet and the through hole to form a pressure signal transmission path, the flowmeter can be made smaller. Moreover, there is an effect that assembly workability is improved and costs can be reduced.

[Brief explanation of the drawing]

Figures 1 to 4 show an embodiment of the present invention, with Figure 1 being a vertical front view of a fluidic flowmeter, Figure 2 being a side view of the same, and Figure 3 showing a fluidic element. FIG. 4 is a longitudinal sectional front view, FIG. 4 is a longitudinal sectional side view thereof, and FIGS. 5 and 6 are sectional views showing the structure of a pressure signal transmission path of a conventional fluidic flowmeter. DESCRIPTION OF SYMBOLS 11... Case, 23... Channel body, 26... Channel, 32... Spray nozzle, 33... Target, 4
1... Piezoelectric film sensor, 43a, 43b... Side wall, 4
6... Pressure signal transmission path, 47... Through hole, 49...
- Pressure wave introduction port, 51...groove. Applicant's Representative Patent Attorney Takehiko Suzue Figure U Figure U

Claims (1)

[Claims] It has an ejection nozzle that ejects fluid into a flow path, and a target is provided in the flow path facing the ejection nozzle, and
In a fluidic flowmeter, side walls are symmetrically provided on both sides of the target, and a piezoelectric film sensor detects alternating pressure waves generated by the vibration phenomenon of the fluid ejected from the ejection nozzle to detect the flow rate. The piezoelectric film sensor is provided at the bottom of the channel main body constituting the channel, and pressure wave inlets are provided at two locations on the lid side of the channel body where alternating pressure waves occur, and these pressure wave inlets and the piezoelectric film sensor are provided. A fluidic flowmeter, characterized in that the fluidic flowmeter communicates with each other via a pressure signal transmission path consisting of a groove provided in the lid of the flow path main body and a through hole provided in the side wall.