JPH04326014A - Fluidic flowmeter - Google Patents

Abstract

PURPOSE:To achieve a smaller size of a flowmeter by enabling the formation of a pressure signal transmission path which transmits a pressure wave with a simple construction. CONSTITUTION:A fluidic flowmeter is provided with a piezoelectric film sensor which checks a alternating pressure wave to be generated by a vibration phenomenon of a fluid being jetted into a passage 26 from a jetting nozzle 32 to detect a flow rate. Recessed grooves are formed at two locations where the alternating pressure wave of a passage body 23 composing the passage 26 is generated while the grooves are closed with a cap 49 leaving a pressure wave introduction port 47a on one end side thereof. A air hole is provided on the bottom of the recessed grooves 47 communicating with the piezo-electric film sensor 41 to form a pressure signal transmission path.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluidic flowmeter that detects a flow rate by detecting alternating pressure waves generated by a vibration phenomenon of a fluid such as gas ejected from an ejection nozzle into a flow path.

0002

[Prior Art] Fluidic flowmeters installed in ordinary homes and measuring the flow rate of gas are, for example,
This method is known from Japanese Patent Publication No. 313018 and Japanese Patent Application Laid-Open No. 1-250725.

A fluidic flowmeter is provided with a jet nozzle on the inlet side of a flow path, and when fluid is jetted from the jet nozzle into the flow path, the jetted fluid flows along, for example, 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 alternating pressure waves occur. The spacing is different from the location and spacing at which alternating pressure waves generally occur, and the two do not correspond.

[0006]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. 9, pressure wave introducing pipes 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 introducing portions 4, 4 provided on the piezoelectric film sensor 3 and the pressure wave introducing pipes 2, 2 are connected to pipes such as vinyl tubes. Connected by 5,5.

Further, FIG. 10 shows pressure wave introduction holes 6, 6 and 7 at intervals corresponding to the positions where alternating pressure waves are generated on the side wall of the channel body 1.
There are 6. On the other hand, a plate 8 is provided on the outer wall of the channel body 1 with a packing 7 interposed therebetween, and a piezoelectric film sensor 3 is provided on this plate 8 with a packing 9 interposed therebetween.

[0009] The plate 8 has through holes 10a, 1 which communicate with the pressure wave introduction parts 4, 4 provided in the piezoelectric film sensor 3.
0a, and through holes 10b, 10b communicating with the pressure wave introducing holes 6, 6 are provided, and these through holes 10a and 1
0b inside the plate 8 to form a pressure wave transmission path 10.
is formed.

0010

However, as mentioned above, in order to compensate for the difference between the spacing between the pressure wave introduction parts of the piezoelectric film sensor and the position and spacing at which alternating pressure waves occur, pipes are connected to Flowmeters configured to transmit gas require space to connect pipes, making the flowmeter larger and requiring more connection points, which poses the risk of gas leakage.

[0011] Furthermore, the structure in which a plate is interposed and a through hole is provided in this plate has the problem that the flowmeter becomes larger due to the thickness of the plate and packing, and furthermore, processing is troublesome and causes an increase in cost. .

[0012] Furthermore, general household gas flowmeters need to be able to measure over a wide range from the maximum usage flow rate to a flow rate of 1/1000 to 1/2000 of the maximum usage flow rate. The measurable range of a fluidic flowmeter using a fluidic flowmeter is about 1/50 of the maximum usable flow rate, and measurement in the micro flow rate range is impossible. Therefore,
A fluidic flowmeter has been developed in which large flow areas are detected by piezoelectric membrane sensors, and minute flow areas are detected by flow sensors.

This fluidic flowmeter is constructed as shown in FIG. That is, 101 is a case, which is composed of a case body 102 and a lid body 103.

A channel main body 105 constituting a channel 104 is provided inside the case 101, and the opening of the channel main body 105 is hermetically closed by a lid 107 via a packing 106. A flow sensor 108 is attached to the side wall of the channel body 105, and the lid body 10
A piezoelectric film sensor 109 is attached to 7.

By the way, as described above, the piezoelectric film sensor 109 is designed to detect alternating pressure waves generated by the vibration phenomenon of the fluid ejected from the ejection nozzle into the flow path 104, and the detected waveform and disturbance It is preferable to install the detection position near the outlet of the ejection nozzle where the influence is small, and for the purpose of detecting a minute flow rate, it is preferable to install the flow sensor 108 at the ejection nozzle part where the flow velocity is the highest.

Therefore, the detection positions of the piezoelectric film sensor 109 and the flow sensor 108 are inevitably very close to each other, and in order to avoid overlapping the two sensors, conventionally the flow sensor 108 and the piezoelectric film sensor 109 are Road 1
They are placed facing each other with 04 in between.

However, in the fluidic flowmeter configured as described above, since the flow sensor 108 and the piezoelectric film sensor 109 are installed facing each other with the flow path 104 in between, the There is a drawback that the case 101 becomes larger.

Further, the flow sensor 108 and the piezoelectric film sensor 109 are attached to the flow channel body 105 in two directions, which increases the number of assembly steps and has the drawback of poor assembly efficiency.

The present 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 flowmeter. The object of the present invention is to provide a fluidic flowmeter that can achieve the following.

[0020]

Means for Solving the Problems and Effects In order to achieve the above object, the present invention provides a method for detecting alternating pressure waves caused by a vibration phenomenon of fluid ejected from an ejection nozzle into a flow path. In a fluidic flowmeter equipped with a piezoelectric film sensor that detects the flow rate by using a piezoelectric film sensor, grooves are formed at two locations where alternating pressure waves occur in the flow channel main body constituting the flow channel, and a pressure wave inlet at one end of these grooves is formed. The grooves are closed by a closing member, and a through hole communicating with the piezoelectric film sensor is provided at the bottom of these grooves to form a pressure signal transmission path.

When the fluid is ejected from the ejection nozzle, the alternating pressure waves generated by the vibration of the fluid are transmitted from the pressure wave introduction port at one end of the groove to the piezoelectric film sensor through the groove and the through hole. The flow rate is measured by a piezoelectric membrane sensor.

[0022] According to a second aspect of the present invention, the closing member is constituted by a cap that is fitted into the groove, and in a third aspect of the present invention, a notch is provided in a part of the circumferential wall of the cap, and the groove is provided with an end face of the notch of the cap. It is characterized by providing a contacting protrusion to position the cap in the circumferential direction.

[0023] According to a fourth aspect of the present invention, the flow sensor and the piezoelectric film sensor are installed adjacent to one side wall of the flow channel main body, so that the flow sensor and the piezoelectric film sensor can be assembled to the flow channel main body from the same direction. It is characterized by what it did.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIGS. 1 and 2 show the entire fluidic flowmeter, and 11 is a case. This case 1
1 is a rectangular box-shaped case body 12;
and a lid body 13 that closes the opening.

A gas inlet body 1 is provided at the bottom of the case body 12.
4 and a gas outlet body 15 are arranged in parallel, and a display window 16 is provided at the top.
is provided. A fluidic element 17 and a cutoff valve 18, which will be described later, are installed in the lower part of the interior of the case 11, and a battery 19, a pressure switch 20, a vibration sensor 21, and an integration display board 22 facing the display window 16 are installed in the upper part.
is installed.

To explain the fluidic element 17, reference numeral 23 is a channel body formed by die-casting or the like, and the opening of this channel body 23 is connected to the packing 2.
4 and is closed by a lid 25, thereby forming a flow path 26.

The flow path 26 is divided by a partition wall 27, with an upstream flow path 28 communicating with the gas inlet body 14 and a downstream flow path 29 communicating 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 20 and the seismic sensor 21 detect an abnormality, the flow path 26 can be shut off by the shutoff valve 18.

As shown in FIG. 3, a jet nozzle 32 is provided on the partition wall 27 of the passage main body 23. As shown in FIG. 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 32a and 32b that project into the upstream flow channel 28 on both sides of the opening in the longitudinal direction.
The nozzle passage length is extended.

A first target 33 is provided in the downstream flow path 29 facing the jet nozzle 32 for stabilizing switching of the fluid flow direction. Side walls 34a and 34b are symmetrically provided on both sides of the first target 33.

Furthermore, a second target 35 is provided in the center located downstream of the first target 33, and a return wall 36 extending in the width direction of the downstream flow path 29 is provided further downstream. It is provided. Return passages 37a and 37b are formed outside the side walls 34a and 34b, and discharge passages 38a and 37b are formed outside both ends of the return wall 36, respectively.
38b is provided.

Therefore, when fluid is ejected from the ejection nozzle 32 toward the downstream flow path 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 is transferred to the left side wall 34b.
Now it flows along the inside of the left side wall 3
A part of the fluid that has flowed to the right side wall 34a becomes a return fluid, and the fluid energy of this return fluid is imparted to the ejected fluid, so that the ejected fluid flows again along the inside of the right side wall 34a. In other words, the configuration is such 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 .

Further, a flow sensor 40 and a piezoelectric film sensor 41 are provided on the side surface of the channel body 23 corresponding to the jet nozzle 32. The flow sensor 40 is
The sensor body 42 consists of a sensor body 42 and a sensor chip 43 equipped with a detection part consisting of a heat generating part and a temperature sensing part.
is fixed to the side surface of the channel main body 23, and the sensor chip 43
facing the jet nozzle 32.

That is, the flow sensor 40 is installed at a position where the flow path is narrowed and the flow velocity is the highest in order to measure a minute flow rate region. Further, the piezoelectric film sensor 41 is for measuring a large flow rate region, and is shown in FIGS. 4 to 6.
As shown in FIG. 2, the sensor body 44 is composed of a sensor body 44 and a pressure wave introduction part 45. The sensor body 44 is fixed to the side surface of the flow path body 23, and the pressure wave introduction part 45 is connected to the vicinity of the outlet of the jet nozzle 32 to prevent vibration phenomena. It is installed at the optimum location for extracting the alternating pressure waves generated by the system.

That is, a pair of circular recesses 46, 46 serving as a pair of grooves are symmetrically provided on the inner wall of the channel body 23 located near the outlet of the jet nozzle 32. The jet nozzle 3 communicates with these concave portions 46, 46.
Concave grooves 47, 47 extending to the outlet side corners of the flow path body 23 are carved in the inner wall of the channel body 23.

Furthermore, a through hole 48 passing through the side surface of the channel body 23 is bored at the bottom of the concave portions 46, 46 at a position offset in the opposite direction to the concave groove 47.
It communicates with 4. Furthermore, projections 46a, 46a projecting into the recesses 46, 46 are provided at the corners of the recesses 46, 46 and the grooves 47, 47.

On the other hand, the concave grooves 47 are formed in the concave portions 46, 46.
Caps 49, 49 as a closing member having a notch 49a in a corresponding portion are fitted. The end surfaces of the notches 49a are in contact with the protrusions 46a, 46a, and the caps 49, 49 are positioned in the circumferential direction. Moreover, the bottom surfaces of the caps 49, 49 are located on the same plane as the bottom surface of the channel body 23 so that the channel 26 is not uneven.

With this configuration, a pressure wave introduction port 47a is formed in the downstream flow path 29 of the flow path main body 23, and opens at the outlet side corner of the jet nozzle 32, and this pressure wave introduction port 47a has a concave shape. The sensor body 44 is connected to the sensor body 44 through the groove 47, the concave portion 46 covered with the cap 49, and the through hole 48.
A pressure signal transmission path 50 is formed.

That is, this pressure signal transmission path 50 forms a detour path for pressure signals, and the sensor body 44 of the piezoelectric film sensor 41 is connected to the sensor body 42 of the flow sensor 40.
This makes it possible to arrange the flow sensor 40 and the piezoelectric film sensor 41 side by side on the same side of the flow path main body 23 while avoiding overlapping.

On the other hand, a flat first rectifying plate 51 made of a wire mesh and a mountain-shaped second rectifying plate 52 made of a wire mesh are installed in the upstream channel 28, and these plates are connected to the channel main body 23. It is provided so that it can be attached and detached.

Next, the operation of the fluidic flowmeter constructed as described above will be explained. Gas inlet body 14
The fluid flowing in passes through the upstream flow path 28 of the flow path 26 and is further rectified by the first rectifier plate 51 and the second rectifier plate 52, and then 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 that has flowed to the right side wall 34a heads toward the discharge passage 38a, but a portion becomes return fluid and returns to the return passage 38a.
Head to 7a.

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. , the fluid energy of this return fluid is imparted to the ejected fluid, and the ejected fluid again hits the right side wall 3.
It starts to flow along the inside of 4a.

That is, from the jet nozzle 32 to the downstream flow path 2
The oscillatory phenomenon of the fluid ejected into the 9 generates alternating pressure waves. This alternating pressure wave, that is, a pressure change caused by a change in the flow direction of the jet from the jet nozzle 32, is detected by the piezoelectric film sensor 41 via the pressure signal transmission paths 50, 50. 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 integration display board 22.

Furthermore, when assembling the flow sensor 40 and piezoelectric film sensor 41 to the channel body 23,
Since the flow sensor 40 and the piezoelectric film sensor 41 are attached to the same side of the channel body 23 from the same direction, it is possible to improve the ease of assembly work, and also the workability during maintenance inspection and repair is improved.

In the above embodiment, in order to form the pressure signal transmission path 50, a recess 46 is provided as a groove in the inner wall of the flow path main body 23, and a recess 4 communicates with the recess 46.
7 is provided and the concave portion 46 is closed with a cap 49 to provide a pressure wave introduction port 47a at one end side of the concave groove 47. However, the concave groove 47 is provided without providing the concave portion 46, The structure may be such that one end of the opening is left open and closed with a cap or the like.

Furthermore, as shown in FIGS. 7 and 8, a stepped portion 53 is provided at the opening edge of the recessed portion 46, and this stepped portion 53
By fitting the disk 54 as a closing member into the recessed portion 46 to close the recessed portion 46, a pressure wave introduction port 47 is formed at one end side of the recessed groove 47.
It may be a structure in which a is provided. Of course, also in this case, the disk 54 is located on the same plane as the bottom surface of the channel body 23 so that no unevenness is formed in the channel 26.

[0050]

As explained above, according to claim 1 of the present invention, grooves are formed at two locations where alternating pressure waves occur in the flow channel main body constituting the flow channel, and at one end side of these grooves. The pressure wave inlet is left and closed by a closing member,
Because a pressure signal transmission path is formed by providing a through hole communicating with the piezoelectric film sensor at the bottom of these grooves, the flowmeter is smaller compared to conventional systems in which a pressure signal transmission path is formed by adding pipes or plates. It is possible to aim for

According to claims 2 and 3, the closing member is constituted by a cap that is fitted into the groove, and a notch is provided in a part of the peripheral wall of the cap, and a protrusion that comes into contact with the end face of the notch of the cap is provided in the groove. Since the cap is provided, the cap can be positioned in the circumferential direction, and the assembly work efficiency can be improved.

According to claim 4, the flow sensor and the piezoelectric film sensor are installed adjacent to one side wall of the channel main body, and the flow sensor and the piezoelectric film sensor can be assembled to the channel main body from the same direction. This has the effect that assembly workability is improved, maintenance, inspection and repair are facilitated, and the flowmeter can be made smaller.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional front view of a fluidic flowmeter according to an embodiment of the present invention.

FIG. 2 is a longitudinal sectional side view of the fluidic flowmeter of the same embodiment.

FIG. 3 is a longitudinal sectional front view of the fluidic element of the same example.

FIG. 4 is a sectional view showing a pressure signal transmission path of the same embodiment.

FIG. 5 is a perspective view of a concave portion and a cap that constitute a pressure signal transmission path in the same embodiment.

FIG. 6 is a sectional view of the pressure signal transmission path of the same embodiment.

FIG. 7 is a perspective view of a concave portion and a disk constituting a pressure signal transmission path according to another embodiment of the present invention.

FIG. 8 is a sectional view of the pressure signal transmission path of the same embodiment.

FIG. 9 is a sectional view showing the structure of a pressure signal transmission path of a conventional fluidic flowmeter.

FIG. 10 is a cross-sectional view showing the structure of a pressure signal transmission path of a conventional fluidic flowmeter.

FIG. 11 is a longitudinal side view of a conventional fluidic flowmeter.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 11... Case, 23... Channel body, 26... Channel, 32... Spout nozzle, 40... Flow sensor, 41... Piezoelectric film sensor,
46... Concave portion, 46a... Protrusion, 47... Concave groove, 47a... Pressure wave introduction port, 49... Cap (closing member), 49a... Notch, 50... Pressure signal transmission path, 54... Disc (closing member)
.

Claims (4)

[Claims] 1. A jet nozzle that spouts fluid into a flow path, a flow sensor that detects the flow velocity of the fluid and detects a flow rate in a minute flow rate range, and a flow sensor that detects the flow rate of the fluid in a minute flow range. In a fluidic flowmeter equipped with a piezoelectric film sensor that detects the flow rate by detecting alternating pressure waves caused by the vibration phenomenon of the fluid ejected into the fluid, alternating pressure waves are generated in the flow channel body constituting the flow channel. Grooves were formed at the locations, pressure wave introduction ports at one end of these grooves were left and closed by a closing member, and through holes communicating with the piezoelectric film sensor were provided at the bottoms of these grooves to form pressure signal transmission paths. A fluidic flowmeter characterized by: 2. The fluidic flowmeter according to claim 1, wherein the closing member is a cap fitted into the groove. 3. The cap is provided with a notch in a part of its peripheral wall, and the groove is provided with a protrusion that abuts the end surface of the notch of the cap that is inserted into the groove to position the cap in the circumferential direction. The fluidic flowmeter according to claim 1 or 2, characterized in that: 4. The fluidic flowmeter according to claim 1, wherein the flow sensor and the piezoelectric film sensor are installed adjacent to one side wall of the channel body.