JPH01227925A - Fluidic flowmeter - Google Patents

Abstract

PURPOSE:To accurately measure the flow rate of a carrying fluid by compensating the electromotive force of a sensor produced by the pressure variation of the fluid. CONSTITUTION:Pressure variation produced by a change in the flowing direction of a jet stream from a jet nozzle 3 is detected with a sensor 14. Inside the sensor 14, a pressure chamber is divided into a central chamber 16a and 1st and 2nd end-section chambers 16b and 16c by means of 1st and 2nd piezoelectric films 15a and 15b and a feedback flow passage 7a is connected with the central chamber 16a and the 1st end-section chamber 16b by a conduit passage 13a. Another feedback flow passage 7b is connected with the 2nd end-section chamber 16c by another conduit passage 13b. A flow rate detecting section 18 detects the flow rate of the jet stream from the nozzle 3 in accordance with the difference between the signals from the 1st and 2nd piezoelectric films 15a and 15b and an abnormality detecting section 19 detects an abnormal state, such as occurrence of an earthquake, etc., in accordance with the signals from the 1st piezoelectric film 15a.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention is characterized in that a pipe constriction section, a jet nozzle, and a pipe expansion section are formed in series in the flow direction, and the jet nozzle and pipe expansion section a pair of control nozzles at the boundary in a direction substantially perpendicular to the jetting direction of the jetting nozzle, and
A pair of return channels are formed facing each other and connect the downstream side of the conduit expansion section with both control nozzles, and detect pressure changes caused by changes in the flow direction of the jet flow from the jet nozzle. This invention relates to a fluidic flowmeter equipped with a sensor for

[Conventional technology]

Conventionally, in a pressure change detection sensor, a pressure chamber is connected to a first pressure chamber (3) using one piezoelectric film (31) as shown in No. 20.
2a) and a second pressure chamber (32b), one of the return flow passages (7a) and the first pressure chamber (32a), and the other return flow passage (7b) and the second pressure chamber (32b), respectively. Another pressure path (1
3a) and (13b), and was provided with a flow rate measuring section (33) that measures the flow rate of the jet stream from the jet nozzle (3) based on a signal from the piezoelectric film (31).

[Problem to be solved by the invention] However, there is a risk that noise due to sensor vibrations caused by earthquakes or pressure fluctuations in the transport fluid will enter the signal from the piezoelectric membrane (31), making it impossible to measure a positive flow rate. There was room for improvement in the negative layer.

The purpose of the present invention is to reliably perform accurate flow rate measurement with almost no measurement errors due to sensor vibrations or pressure fluctuations of the transport fluid, and to effectively utilize the configuration for this purpose to prevent earthquake occurrence and transportation. The purpose is to detect the occurrence of an abnormal situation such as an abnormal pressure drop in a fluid.

[Means to solve the problem]

A characteristic configuration of the present invention is that in a sensor that detects a pressure change caused by a change in the flow direction of a jet flow from a jet nozzle,
The pressure chamber is divided into a central chamber and first and second end chambers on both sides thereof by first and second piezoelectric films, and a first chamber is connected to one of the return channels for controlling changes in the flow direction of the jet flow. A pressure guiding path is connected to the central chamber and the first end chamber, and a second pressure path connected to the other of the return flow paths is connected to the second end chamber,
of the jet from the jet nozzle based on a difference signal between a first signal from the first piezoelectric film facing the first end chamber and a second signal from the second piezoelectric film facing the second end chamber. A flow rate detection unit for measuring the flow rate is provided, and the first piezoelectric film from the first piezoelectric film is
The present invention is provided with an abnormality detection section that detects an abnormal situation based on a signal, and its effects are as follows.

[Function] In other words, under normal conditions, the electromotive force V of the first signal from the first piezoelectric membrane facing the central chamber and the first end chamber connected to the first pressure path is generated by the sensor due to the pressure fluctuation of the transport fluid. When an external vibration such as an earthquake is applied to the sensor, the electromotive force Δv1 due to the vibration becomes the sum of the electromotive force Δv2 due to the external vibration and the electromotive force Δv1 due to the pressure fluctuation, and the No electromotive force is generated due to pressure fluctuations.

On the other hand, under normal conditions, the electromotive force v2 of the second signal from the central chamber connected to the first pressure path and the second piezoelectric film connected to the second pressure path is equal to the pressure p of the first pressure path and the second piezoelectric film connected to the second pressure path. An electromotive force Vp proportional to the difference in pressure P2 between the two pressure paths and an electromotive force Δ due to the pressure fluctuation.
V, and when external vibration is applied to the sensor, it becomes the sum of the electromotive force p, ΔV l+ Δv2.

Therefore, the electromotive force detected by the flow rate detection section during normal operation is the difference signal between the first signal and the second signal, that is, Vp=CVp+ΔV+)−ΔV.

Therefore, accurate flow rate measurement with almost no errors due to pressure fluctuations can be achieved.

Furthermore, when external vibrations such as an earthquake are applied to the sensor, the electromotive force detected by the flow rate detection section is Vp-(Vp+Δ
ν1+ΔVZ) −(ΔV, −+−ΔVZ), and it is possible to realize accurate flow rate measurement with no errors due to pressure fluctuations and external vibrations.

Furthermore, the electromotive force detected by the abnormality detection section is ΔV during normal operation.
3. When external vibrations such as earthquakes are applied, ΔV, +Δv2
, ΔV when the pressure of the transport fluid abnormally decreases by Δv3,
-Δv3, it is possible to easily and reliably detect whether or not an abnormal situation has occurred, such as an earthquake or an abnormal pressure drop in transport fluid, based on the electromotive force detected by the abnormality detection unit. , appropriate measures such as blocking can be taken.

(Effects of the invention) As a result, it has become possible to provide a fluidic flowmeter with even better performance, which can reliably perform accurate flow measurement with almost no measurement errors due to disturbances, and can detect the occurrence of abnormal situations. .

(Example] Next, an example will be shown with reference to FIG.

A pair of first flow path forming members (4a) and (4b) that form a conduit constriction section (2) and a jet nozzle (3) in the pipe (1).
) are arranged symmetrically with respect to the pipe center axis (P), and the fluid is smoothly guided to the jet nozzle (3) by the action of the pipe constriction part (2), and the fluid is guided from the jet nozzle (3) to the pipe center. It is configured to eject fluid almost parallel to the axis (P), and the pipe expansion part (
5), a pair of control nozzles (6a).

(6b), and a pair of partition walls defining a pair of return channels (7a) and (7b) that communicate the control nozzles (6a) and (6b) separately with the downstream side of the expanded pipe section (5). (8a) and (8b) are arranged symmetrically with respect to the tube center axis (P), and the pair of control nozzles (6a) and (6b) are arranged at approximately right angles to the jetting direction of the jetting nozzle (3). It is directed toward the direction and also directed toward each other. A pair of partition walls (9a
), a pair of discharge channels (10a) in collaboration with (9b)
, (10b) is provided so as to block the downstream side of the expanded pipe section (5), and the partition wall (11) forming the two-phase outlet channel (10
a), the inlet of (10b) is connected to both station return passage (7a),
(7b) are connected separately to the inlet side.

In other words, when fluid ejection from the ejection nozzle (3) starts, the ejected fluid flows to one partition wall (8a) due to the Coanda effect.
), and therefore large fluid energy is applied from the return flow path (7a) to the control nozzle (6a) located on the partition wall (8a) side, and the ejected fluid flows along the partition wall (8b) on the opposite side. The fluid energy from the opposite control nozzle (6b) causes the jet fluid to flow again along the partition wall (8a) along which it started, and in this way the jet nozzle (3 ) so that the fluid flows along the partition walls (8a) and (8b) alternately, so that as the amount of fluid ejected increases, the period becomes shorter,
Further, the flow direction of the ejected fluid is configured to change in a state where there is a quantitative correlation.

(12) for stabilizing the switching of the flow direction in the expanded pipe section (5), and the measured flow rate range is, for example, 150 to 3.0, which is necessary for a household gas meter for city gas.
00 ffi/h, the error in meteor measurement can be kept within the detection tolerance of a household gas meter for city gas, for example.

The first and second pressure impulse paths (13a) and (13b) are connected to both the a reflux paths (7a) and (7b) separately,
It is connected to a sensor (14) that detects pressure changes caused by changes in the flow direction of the jet flow from the jet nozzle (3).

In the sensor (14), the pressure chamber is connected to the central chamber (16a) by the first and second piezoelectric films (15a) and (15b).
and the first and second end chambers (16b) on both sides thereof, (1
6c), and the first pressure path (13a) is divided into a central chamber (1
6a) and the first end chamber (16b), and the second pressure path (
13b) is connected to the second end chamber (16c).

A first subtraction circuit (17a) that extracts a difference signal between the signals from the front and back sides of the first piezoelectric film (15a) facing the central chamber (16a) and the first end chamber (16b) as a first signal;
a) and the second piezoelectric film (15b) facing the second end chamber (16c).
) is provided, and a second subtraction circuit (17b) is provided to take out the difference signal between the signals from the front and back sides of each as a second flash, and a flow rate detection section (18) is connected to the first and second subtraction circuits (17a) and (17b). Then, an abnormality detection section (19) is installed in the first 1γ circuit (17a).
) is connected.

The flow rate detection unit (18) includes a third subtraction circuit (18a) that extracts a difference signal between the first signal and the second signal;
) is provided with a flow rate detection means (18b) that calculates and displays the flow rate from the frequency of the sinusoidal waveform signal from the sine waveform signal.

The first signal is sent to the abnormality detection unit (19) from the first setting device (20a).
), the first determining means (19a) detects the occurrence of an earthquake based on the detection that the intensity is less than the set intensity by the second setting device (20b); A second device detects an abnormal pressure drop in the transport fluid.
Judgment means (19b), first and second judgment means (19a)
, Output means for automatically closing and operating the shutoff valve (21) and automatically operating the alarm (22) in the event of an earthquake or abnormal pressure drop in the medium-sized product delivery fluid based on the information from (19b); (19c) is provided.

[Another example] Next, another embodiment will be described.

The specific structure of the fluidic flowmeter can be changed as appropriate; for example, the shapes of the partition walls (8a), (8b), and (11) can be changed appropriately, or the shape and arrangement of the target (12) can be changed as appropriate. , the target (12) can be omitted, etc.

The specific configurations of the flow rate detection section (18) and the abnormality detection section (19) can be changed as appropriate. For example, the abnormality detection section (19) can be configured to display only the electromotive force of the first signal, so that the occurrence of an abnormal situation cannot be artificially detected. For example, it is possible to configure the system to make a determination based on the following information.

Flowmeters are mainly used for industrial and household purposes, such as fuel gas and water supply, but their uses are not specific.

Incidentally, although reference numerals are written in the claims section for convenience of comparison with the drawings, the present invention is not limited to the structure shown in the attached V-side.

[Brief explanation of the drawing]

FIG. 1 is a conceptual diagram showing an embodiment of the present invention, and FIG. 2 is a conceptual diagram of a conventional example. (2)...Pipe constriction part, (3)...Blowout nozzle, (5)...Pipe enlargement part, (6a)
, (6b) --11i11? 'Jll nozzle,
(7a), (7b) --return flow path, (13a)
, (13b) -... pressure path, (14)...
...Sensor, (15a), (15b)...
...Piezoelectric film, (16a)...Central chamber, (16
b), (16c)... End chamber, (18).
...flow rate detection section, (19) ...abnormality detection section, (19a), (19b) --determination means, (
19c)--Output means.

Claims (1)

[Scope of Claims] 1. A conduit constriction section (2), a jet nozzle (3), and a conduit expansion section (5) are formed in series in the flow direction, and the conduit constriction section (2), the jet nozzle (3), and the conduit expansion section (5) are formed in series in the flow direction, and A pair of control nozzles (6a) and (6b) are connected to the boundary between the jet nozzle (3) and the jet nozzle (3).
The control nozzles (6a) and (6b) are formed in a direction substantially perpendicular to the ejection direction of the control nozzles (6a) and (6b)
A pair of return channels (7a) and (7b) are formed which connect the downstream sides of the expanded pipe section (5), respectively, and pressure changes caused by changes in the flow direction of the jet flow from the jet nozzle (3) are formed. This fluidic flowmeter is equipped with a sensor (14) for detecting pressure, and in the sensor (14), a pressure chamber is connected to a central chamber (16a) by first and second piezoelectric films (15a) and (15b). The first and second end chambers (16b
), (16c), and one of the return channels (7a
) is connected to the central chamber (16).
a) and the first end chamber (16b), and a second pressure path (13b) connected to the other (7b) of the return flow path is connected to the second end chamber (16c); End chamber (16b
) a first signal from the first piezoelectric film (15a) facing the
The second piezoelectric film (15) facing the second end chamber (16c)
a flow rate detection unit (18) that measures the flow rate of the jet flow from the jet nozzle (3) based on the difference signal from the second signal from b);
and an abnormality detection section (19) for detecting an abnormal situation based on a first signal from the first piezoelectric film (15a). 2. The abnormality detection unit (19) detects the occurrence of an earthquake based on the detection of a first signal having a set strength or higher.
The fluidic flowmeter according to claim 1, which has a). 3. The abnormality detection unit (19) detects an abnormal pressure drop of the transport fluid based on the detection of the first signal having a set strength or less.
Claim 1 or 2 comprising a determining means (19b)
Fluidic flowmeter as described. 4. The fluidic flowmeter according to claim 2 or 3, wherein the abnormality detection section (19) is provided with an output means (19c) for automatically shutting off fluid transport based on detection of an abnormal situation.