JP2512518B2 - Fluidic flow meter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of use] The present invention forms a pipe contracting portion, a jet nozzle, and a pipe expanding portion in that order in the flow direction to form the jet nozzle and the pipe expanding portion. A pair of control nozzles are formed in the boundary portion in a direction substantially perpendicular to the ejection direction of the ejection nozzle, and face each other, and the control nozzles and the downstream side of the conduit enlargement portion are formed. Forming a pair of return channels to connect,
The present invention relates to a fluidic flow meter provided with a sensor that detects a pressure change due to a change in the flow direction of a jet flow from the jet nozzle.

[Conventional technology]

Conventionally, in a pressure change detection sensor, as shown in FIG. 2, the pressure chamber is composed of a single piezoelectric film (31) and a first pressure chamber (32).
a) and the second pressure chamber (32b), and one of the return flow paths (7
a) and the first pressure chamber (32a) and the other return flow passage (7b) and the second pressure chamber (32b) are connected by separate pressure guide passages (13a) and (13b), respectively, and the piezoelectric film (31 ), A flow rate measuring section (33) for measuring the flow rate of the jet flow from the jet nozzle (3) is provided.

[Problems to be Solved by the Invention]

However, there is a risk that noise due to sensor vibrations due to earthquakes and pressure fluctuations in the transport fluid will enter the signal from the piezoelectric film (31), making it impossible to accurately measure the flow rate, and there is room for further improvement. there were.

An object of the present invention is to make it possible to reliably perform accurate flow rate measurement with almost no measurement error due to vibration of a sensor or pressure fluctuations of a transport fluid, and moreover, effectively utilize the configuration for that to generate an earthquake or transport fluid. It is to be able to detect the occurrence of abnormal situations such as abnormal pressure drop.

[Means for solving the problem]

According to a characteristic configuration of the present invention, in a sensor for detecting a pressure change caused by a change in a flow direction of a jet flow from an ejection nozzle, the pressure chamber is formed by the first and second piezoelectric films and the central chamber and first and second ends on both sides thereof. A first chamber connected to one of the return flow paths for dividing the flow direction of the jet flow
The first pressure passage is connected to the central chamber and the first end chamber, the second pressure passage connected to the other of the return flow passages is connected to the second end chamber, and faces the first end chamber. A first signal from the piezoelectric film and a second signal from the second piezoelectric film facing the second end chamber.
A flow rate detection unit for measuring the flow rate of the jet flow from the ejection nozzle based on a difference signal from the signal, and an abnormality detection unit for detecting an abnormal situation based on the first signal from the first piezoelectric film. And its effects are as follows.

[Work]

That is, the electromotive force V ₁ of the first signal from the first piezoelectric film facing the central chamber and the first end chamber connected to the first pressure guiding path is normally caused by the vibration of the sensor due to the pressure fluctuation of the transport fluid. to electromotive force [Delta] V ₁ becomes, when an external vibration such as an earthquake is applied to the sensor, the sum of the electromotive force [Delta] V ₂ due to the external vibration and the electromotive force [Delta] V ₁ caused by the pressure fluctuation, the first pressure introduction passage No electromotive force is generated due to pressure fluctuation.

On the other hand, the electromotive force V ₂ of the second signal from the central chamber connected to the first pressure guiding path and the second piezoelectric film connected to the second pressure guiding path is equal to the pressure P _{1 of the first} pressure guiding path in the normal state. The sum of the electromotive force Vp proportional to the difference in the pressure P ₂ of the second pressure guiding path and the electromotive force ΔV ₁ due to the pressure fluctuation, and when external vibration is applied to the sensor, the electromotive force Vp, ΔV ₁ , It is the sum of ΔV ₂ .

Therefore, the electromotive force detected by the flow rate detector during normal operation is the difference signal between the first signal and the second signal, that is, Vp = (Vp + ΔV ₁ ) −ΔV ₁ , and there is almost no error due to pressure fluctuations. Flow rate measurement can be realized.

Further, the electromotive force external vibration caused by an earthquake are detected by the flow rate detecting unit when applied to the _{sensor, Vp = (Vp + ΔV 1} + ΔV 2) - (ΔV 1 + ΔV 2) , and the error caused by the pressure fluctuations and external vibrations It is possible to realize accurate flow rate measurement that is rare.

Furthermore, the electromotive force detected by the abnormality detection unit is Δ
V ₁ is ΔV ₁ + ΔV ₂ when an external vibration such as an earthquake is applied, and ΔV ₁ −ΔV ₃ when the pressure of the transport fluid is abnormally decreased by ΔV ₃ , so based on the electromotive force detected by the abnormality detection unit, It is possible to easily and surely detect whether or not an abnormal situation such as an earthquake occurrence or an abnormal pressure drop of the transportation fluid has occurred, and appropriate measures such as an emergency cutoff of fluid transportation can be taken.

〔The invention's effect〕

As a result, it has become possible to provide a fluidic flow meter that is capable of reliably performing accurate flow rate measurement with almost no measurement error due to disturbance, and that is capable of detecting the occurrence of abnormal situations, and that is even more excellent in terms of performance.

〔Example〕

 Next, an embodiment is shown in FIG.

In the pipe (1), the pipe passage reducing portion (2) and the jet nozzle (3)
Forming a pair of first flow path forming members (4a), (4b),
The pipe central axis (P) is arranged symmetrically, the fluid is smoothly guided to the jet nozzle (3) by the action of the pipe channel contracting portion (2), and the pipe central axis (from the jet nozzle (3) ( P), so that the fluid is ejected almost in parallel with the pipe expanding portion (5),
A pair of control nozzles (6a), (6b), and a pair of return flow paths (7a), (7b) that communicate the control nozzles (6a), (6b) with the downstream side of the duct expansion part (5) separately. A pair of partition walls (8a) and (8b) for partitioning and forming are defined symmetrically with respect to the pipe center axis (P), and the pair of control nozzles (6a) and (6b) are connected to the ejection nozzle (3). They are directed almost at right angles to the ejection direction and face each other. A pair of partition walls (9a),
A partition wall (11) forming a pair of discharge passages (10a) and (10b) in cooperation with (9b) is provided in a state of blocking the downstream side of the expanded pipe portion (5), and both discharge passages (10a) are provided. ) And (10b) are communicated with the inlets of both return flow paths (7a) and (7b) separately.

In other words, when the ejection of the fluid from the ejection nozzle (3) is started, the ejected fluid is discharged by one of the partition walls (8
a), so that a large amount of fluid energy is applied from the return flow path (7a) to the control nozzle (6a) located on the side of the partition wall (8a), so that the jetted fluid is ejected on the opposite side of the partition wall (8a).
b) and then the fluid energy from the opposite control nozzle (6b) causes the jetted fluid to flow again along the original partition (8a), thus The fluid from the nozzle (3) is
A) and (8b) are arranged alternately so that the flow direction of the ejected fluid changes in a shorter period and in a quantitatively correlated state as the ejected fluid amount increases. I am doing it.

A target (12) for stabilizing the flow direction switching in the expanded pipe section (5) is provided, and the measured flow rate range is increased to, for example, 150 to 3,000 l / h required as a household gas meter for city gas, The error in the flow rate measurement is configured to be within the detection tolerance of a household gas meter for city gas, for example.

The pressure due to the change in the flow direction of the jet flow from the jet nozzle (3) is applied to the first and second pressure guiding passages (13a) and (13b), which are separately communicated with the both return flow passages (7a) and (7b). It is connected to a sensor (14) that detects changes.

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

A first subtraction circuit (17a) for extracting as a first signal a difference signal between the front and back surfaces of the first piezoelectric film (15a) facing the central chamber (16a) and the first end chamber (16b), the central chamber (16a) And a second subtraction circuit (17) for taking out a difference signal of signals from the front and back of the second piezoelectric film (15b) facing the second end chamber (16c) as a second signal.
b) is provided, the flow rate detection unit (18) is connected to the first and second subtraction circuits (17a) and (17b), and the abnormality detection unit (19) is connected to the first subtraction circuit (17a).

The flow rate detection unit (18) calculates the flow rate from the frequency of the sinusoidal waveform signal from the third subtraction circuit (18a) and the third subtraction circuit (18a) that extracts the difference signal between the first signal and the second signal. A flow rate detecting means (18b) for displaying is provided.

The first signal is sent to the abnormality detector (19) as the first setting device (20a).
The first determination means (19a) for detecting the occurrence of an earthquake on the basis of the detection that the intensity is equal to or higher than the set intensity by the, and the transport fluid based on the detection that the first signal is equal to or lower than the intensity set by the second setter (20b) Of the shutoff valve (21) when an earthquake occurs and when the transport fluid has an abnormal pressure drop based on information from the second determining means (19b) for detecting the abnormal pressure drop of the first, second and first determining means (19a), (19b). ) Is automatically closed and an output device (19c) for automatically activating the alarm (22) is provided.

[Another embodiment]

 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), (11) can be changed appropriately, and the shape and arrangement of the target (12) can be changed appropriately. , The target (12) can be omitted.

The specific configurations of the flow rate detection unit (18) and the abnormality detection unit (19) can be appropriately changed, and for example, the abnormality detection unit (19) is only displayed with the electromotive force of the first signal so that the occurrence of the abnormal situation is artificially performed. It is possible to configure such as to determine.

The flow meter is mainly used for fuel gas, water supply, etc. for industrial and household purposes, but is not specified for its use.

It should be noted that reference numerals are added to the claims for convenience of comparison with the drawings, but the present invention is not limited to the structures of the accompanying drawings by the entry.

[Brief description of drawings]

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) …… Conduit reduction part, (3) …… Spout nozzle, (5)
…… Pipe expansion part, (6a), (6b) …… Control nozzle, (7
a), (7b) ... return flow path, (13a), (13b) ... pressure guiding path, (14) ... sensor, (15a), (15b) ... piezoelectric film, (16a) ... center Chamber, (16b), (16c) …… End chamber, (18) …… Flow rate detector, (19) …… Abnormality detector,
(19a), (19b) ... determination means, (19c) ... output means.

Claims (4)

(57) [Claims] 1. A pipe contracting portion (2), a jet nozzle (3) and a pipe expanding portion (5) are formed in that order in the flow direction,
At the boundary between the jet nozzle (3) and the enlarged pipe section (5),
A pair of control nozzles (6a), (6b) are formed in a direction substantially perpendicular to the ejection direction of the ejection nozzle (3) and face each other. 6
b) A pair of return flow paths (7a) and (7b) are formed to connect the downstream sides of the expanded pipe section (5) to each other, which is caused by a change in the flow direction of the jet flow from the jet nozzle (3). A fluidic flowmeter provided with a sensor (14) for detecting a pressure change, wherein the pressure chamber is a first chamber in the sensor (14).
And the central chamber (16a) by the second piezoelectric films (15a) and (15b)
And the first and second end chambers (16b) and (16c) on both sides thereof and the first pressure guiding passageway (13a) connected to one of the return passageways (7a) is connected to the central chamber (16a). And a second pressure guiding passageway (13b) connected to the other end (7b) of the return flow passage to the second end chamber (16c), and the first end chamber (16b) is connected to the first end chamber (16b).
The first from the first piezoelectric film (15a) facing the end chamber (16b)
A flow rate detector that measures the flow rate of the jet flow from the jet nozzle (3) based on the difference signal between the signal and the second signal from the second piezoelectric film (15b) facing the second end chamber (16c). (1
A fluidic flowmeter provided with 8) and an abnormality detecting section (19) for detecting an abnormal situation based on the first signal from the first piezoelectric film (15a). 2. The fluidic flow rate according to claim 1, wherein the abnormality detection section (19) has a first determination means (19a) for detecting the occurrence of an earthquake on the basis of the detection of a first signal of a set intensity or more. Total. 3. The abnormality detecting section (19) has a second judging means (19b) for detecting an abnormal pressure drop of the transport fluid based on the detection of a first signal having a set intensity or less. The fluidic flowmeter described in 2. 4. The fluidic flow meter according to claim 2, wherein the abnormality detecting section (19) is provided with an output means (19c) for automatically interrupting fluid transportation based on the detection of an abnormal situation.