JP2000097744A - Flowmeter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flowmeter which can economically and highly accurately measure a flow rate. SOLUTION: A flowmeter 9 for a small flow rate, a differential pressure control valve 7 whose valve is opened/closed by a differential pressure in a fluid and a solenoid valve 8 whose valve is opened/closed by function of electromagnetic force are provided in parallel, while the flowmeter 9 for a small flow rate, the differential pressure control, valve 7 and the solenoid valve 8 are provided in series with a flowmeter 10 for a large flow rate. The solenoid valve 8 is controlled according to a flow rate measured by the flowmeter 10 for a large flow rate or the flowmeter 9 for a small flow rate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a flow meter for gas or the like.

[0002]

2. Description of the Related Art
The flow meter combines a small flow rate flow meter and a large flow rate flow meter in order to accurately measure the gas flow rate over a wide range, and when the gas has a small flow rate, switches to the small flow rate flow meter. While measuring the flow rate, when the gas has a large flow rate, the flow rate is measured by switching to a large flow rate flow meter.

[0003] One of such flow meters is shown in FIG.
As shown in the figure, the flow meter for small flow rate (21) and the solenoid valve (2
3) are connected in parallel, and those and a large flow meter (22) are connected in series. According to this, when the gas flow rate is small, the solenoid valve (23)
Is closed and the flow rate is measured by the small flow rate meter (21). On the other hand, if the flow rate is large, the solenoid valve (23) is opened and the flow rate is measured by the large flow rate flow meter (22). The flow rate can be measured by automatically switching between the small flow rate meter (21) and the large flow rate flow meter (22) according to the flow rate.

However, in a flow meter such as a gas meter which is used for a long period of nearly 10 years, there is usually a differential pressure across the solenoid valve (23) in order to suppress the power consumption of the solenoid valve (23). A two-way valve that opens and closes only when the pressure is equal to or lower than a certain pressure is used. For this reason, when the differential pressure across the solenoid valve (23) suddenly increases, the solenoid valve (2
3) does not operate normally, and has a drawback that the flow rate cannot be accurately measured over a wide range while suppressing power consumption.

On the other hand, in addition to the flow meter using the above-mentioned solenoid valve (23), as shown in FIG.
And a differential pressure control valve (24) connected in parallel, and a large flow meter (22) connected in series with them.
According to this, when the gas flow rate is a small flow rate, the switching valve (24b) of the differential pressure control valve (24) closes the outlet (24a) because the differential pressure is small, and the small flow rate meter ( While the flow rate is measured by 21), in the case of a large flow rate, the switching valve (24b) of the differential pressure control valve (24) opens the outlet portion (24a) because the differential pressure is large, and the flow meter for large flow rate As the flow rate is measured by (22), the flow rate can be measured by automatically switching between the small flow rate meter (21) and the large flow rate flow meter (22) according to the flow rate. .

However, if the valve is opened and closed only by the pressure difference between the gas before and after the differential pressure control valve (24) as described above, when the valve just opens and closes, the fluctuation of the flow rate with respect to the fluctuation of the valve lift. In some cases, so-called hunting may occur, and the stability is poor.

In view of the above-mentioned prior art, the present invention measures the flow rate economically and accurately by suppressing power consumption and stably switching between a small flow rate flow meter and a large flow rate flow meter. It is an object of the present invention to provide a flowmeter capable of performing the above.

[0008]

The object of the present invention is to provide a flow meter having a small flow rate meter for measuring a small flow rate fluid and a large flow rate flow meter for measuring a large flow rate fluid. A flow rate meter for small flow rate, a differential pressure control valve, and a solenoid valve. And a large flow meter are provided in series, and the solenoid valve is controlled in accordance with the flow rate measured by the small flow meter or the large flow meter. You.

According to this flow meter, when the fluid has a small flow rate, the differential pressure control valve is closed because the differential pressure is small. Therefore, the solenoid valve is also closed, so that the small flow rate flow meter is used. The flow rate is measured with high accuracy. When the flow rate gradually increases and falls within the measurement range of the large flow rate meter, the flow rate is accurately measured by the large flow rate meter by opening the solenoid valve. Further, by closing the solenoid valve before the flow rate increases and the differential pressure control valve is opened, the differential pressure control valve is opened with good stability, and the flow rate is accurately measured by the large flow rate flow meter. When the flow rate decreases, the flow is measured in a high flow rate or a small flow rate by performing the reverse of the above operation.

As described above, since the solenoid valve is controlled so as to open and close only in response to a certain flow rate, the solenoid valve can be opened and closed with a small force, and the power consumption can be reduced. be able to. Further, before the differential pressure control valve opens and closes, the flow rate is largely changed by controlling the opening and closing of the solenoid valve, so that hunting of the differential pressure control valve can be prevented.

When the flow rate data measured by the small flow rate meter becomes equal to or more than a first reference value which is an optimal flow value for switching between the small flow rate flow meter and the large flow rate flow meter,
When the solenoid valve is opened and the flow rate data measured by the large flow meter becomes equal to or more than the second reference value which is the optimal flow value for opening the differential pressure control valve, the solenoid valve is closed. On the other hand, when the flow rate data measured by the large flow rate flow meter becomes equal to or less than a third reference value that is a flow rate value optimal for closing the differential pressure control valve, the solenoid valve is opened, It is preferable that the solenoid valve be closed when the flow rate data measured by the large flow rate flow meter becomes equal to or less than the first reference value.

According to this, when the fluid has a flow rate value (first reference value) that is optimal for switching between the small flow rate flow meter and the large flow rate flow meter, and is optimal for opening and closing the differential pressure control valve. When the flow rate value (second or third reference value) is reached, the solenoid valve opens and closes, so that the above-described suppression of power consumption and prevention of hunting can be reliably achieved.

[0013]

Next, an embodiment in which the present invention is applied to a gas flowmeter will be described.

FIGS. 1 to 4 are views showing a gas flow meter according to an embodiment of the present invention. In these figures, (1) is a casing, and a gas pipe (2) is provided so as to pass through the casing (1). And this gas pipe (2) is inside the casing (1),
The gas pipe for the differential pressure control valve (3), the gas pipe for the solenoid valve (4), and the gas pipe for the small flow rate (5) are branched in parallel into three directions. ) And (5) are joined to form a large flow gas pipe (6). In addition, the above-described gas pipe (3) for the differential pressure control valve, the gas pipe (4) for the solenoid valve, the gas pipe (5) for the small flow rate, and the gas pipe (6) for the large flow rate respectively include:
A differential pressure control valve (7), a solenoid valve (8), a flow meter for small flow (9) and a flow meter for large flow (10) are interposed, and a solenoid valve (8) and a flow meter for small flow ( The control unit (11) is electrically connected to the flow meter (9) and the large flow rate meter (10). The small flow meter (9) or the large flow meter (10) measures the flow rate of the gas flowing through the small flow gas pipe (5) or the large flow gas pipe (6). , The flow rate of the gas is measured every two seconds, the result is displayed, and the flow rate data is sequentially transmitted to the control unit (11). As will be described later, when the flow rate of the gas is a small flow rate, the measurement result of the small flow rate meter (9) is adopted, whereas when the gas flow rate is a large flow rate, the measurement result of the large flow rate meter (10) is used. The result is adopted. In this embodiment, the flow rate of the gas is measured every two seconds.
The measurement is not limited to this, and the measurement may be performed at other time intervals or may be performed continuously.

The control unit (11) monitors gas flow data transmitted from the small flow meter (9) or the large flow meter (10), and based on the flow data, controls the solenoid valve ( 8) is transmitted.

More specifically, the control unit (11)
When the fluid has a small flow rate, the flow rate data transmitted from the small flow rate flow meter (9) is monitored, and when the flow rate data exceeds the first reference value (A), an open signal is sent to the solenoid valve (8). Send This time, the flow rate data transmitted from the large flow rate flow meter (10) is monitored, and when the flow rate data exceeds the second reference value (B) immediately before the differential pressure control valve (7) is opened. A closing signal is transmitted to the solenoid valve (8), and thereafter, the flow rate data transmitted from the large flow rate flow meter (10) is monitored.

Further, the flow rate decreases, and the flow meter for large flow rate (1
When the flow rate data transmitted from 0) becomes equal to or less than the third reference value (C) before the differential pressure control valve (7) closes,
An open signal is transmitted to the solenoid valve (8), and thereafter the flow rate data transmitted from the large flow rate meter (10) is monitored.
When the flow rate data becomes equal to or less than the first reference value (A),
A closing signal is transmitted to the solenoid valve (8), and thereafter, the flow rate data transmitted from the small flow rate meter (9) is monitored. The first reference value refers to a flow rate value optimal for switching between a small flow rate flow meter and a large flow rate flow meter. Further, the second reference value is a flow rate value optimal for opening the differential pressure control valve, and the third reference value is a flow rate value optimal for closing the differential pressure control valve. Say.

The electromagnetic valve (8) controls the gas flowing through the electromagnetic valve gas pipe (4) by the action of an electromagnetic force.
According to a signal transmitted from the control unit (11),
It opens and closes a valve (not shown) provided inside. That is, the solenoid valve (8) opens the valve when receiving an open signal from the control unit (11) and allows gas to flow, while receiving a close signal from the control unit (11) closes the valve and shuts off gas. I do.

The differential pressure control valve (7) supplies gas according to the differential pressure between the outlet (10a) of the large flow rate meter (10) and the inlet (7a) of the differential pressure control valve (7). The gas flows into or shuts off the gas pipe (3) for the differential pressure control valve. As shown in FIG. 2, the diaphragm (12) arranged in the horizontal direction divides the chamber equally into two chambers. The chamber is divided into a chamber (14) and a lower pressure chamber (15). The upper pressure chamber (14) is connected to the outlet (10a) of the large flow rate meter (10) via the connecting pipe (16), while the lower pressure chamber (10) of the diaphragm (12) is connected. A switching valve (13) having a circular cross section is provided on the 15) side, and opens and closes the outlet (7b) of the differential pressure control valve (7) in accordance with the vertical movement of the diaphragm (12). It has been done.

Therefore, the pressure in the upper pressure chamber (14) is equal to the pressure at the outlet (10a) of the flow meter for large flow (10), and the pressure in the lower pressure chamber (15) is equal to the pressure of the differential pressure control valve (7). Entrance (7
a), and the pressure difference between the upper pressure chamber (14) and the lower pressure chamber (15) is directly changed to the outlet (10a) of the large flow rate meter (10) and the differential pressure control valve (7). ), The pressure difference causes the diaphragm (12) to move in the direction of the membrane pressure, and the switching valve (13) attached to the diaphragm (12) to reciprocate up and down. Is caused.

For example, the upper pressure chamber (14) and the lower pressure chamber (1)
5) When the differential pressure is small, that is, when the gas has a small flow rate, the pressure difference between the outlet (10a) of the large flow meter (10) and the inlet (7b) of the differential pressure control valve (7) is small. If smaller,
As shown by the solid line in FIG. 2, the diaphragm (12) moves downward, and as it moves, the switching valve (13) also moves downward, closing the outlet (7b) of the differential pressure control valve (7). I do. Further, the pressure of the lower pressure chamber (15) is changed to the upper pressure chamber (14).
In other words, when the gas is at a large flow rate and the pressure at the inlet (7a) of the differential pressure control valve (7) is larger than the pressure at the outlet of the large flow meter (10), As shown by the dotted line 2, the diaphragm (12) moves upward, and as the diaphragm moves, the switching valve (13) also moves upward, opening the outlet (7b) of the differential pressure control valve (7). .

Next, a method of measuring a gas flow rate using the above-described gas flow meter will be described as follows.

The gas has a small flow rate and the flow rate is the first reference value (A)
When the pressure difference has not been reached, as shown in FIG. 3A, the differential pressure between the outlet (10a) of the large flow rate meter (10) and the inlet (7a) of the differential pressure controller (11) is Since the pressure difference between the upper pressure chamber (14) and the lower pressure chamber (15) of the differential pressure control valve (7) is small, the diaphragm (12) is in the initial state of moving downward, and the switching valve (13) ) Closes the outlet (7b) of the differential pressure control valve (7). Also, the solenoid valve (8) does not receive an open signal from the control unit (11) until the flow rate reaches the first reference value (A), so the valve provided inside is closed. For this reason, the gas does not flow into either the gas pipe for the differential pressure control valve (3) or the gas pipe for the solenoid valve (4), and flows only through the gas pipe for small flow (5). The gas flow rate is measured by the small flow rate meter (9), the flow rate data is transmitted to the control unit (11) every two seconds, and the control unit (11) directly controls the small flow rate flow meter (9). ) Is monitored.

Thereafter, the flow rate of the gas increases, and the flow rate data of the gas by the small flow rate meter (9) becomes the first reference value (A).
When the opening signal is reached, an opening signal is transmitted from the control unit (11) to the solenoid valve (8), and as shown in FIG. 3 (b), the solenoid valve (8) receiving the opening signal switches the valve provided inside. Open.
Therefore, the gas flows through the large flow gas pipe (6) through the solenoid valve gas pipe (4), so that the gas flow is measured by the large flow gas pipe (6), The flow rate data is transmitted to the control unit (11) every two seconds, and the control unit (11) directly monitors the flow rate data of the large flow rate meter (10). At this time, the differential pressure between the outlet (10a) of the flow meter for large flow rate (10) and the inlet (7a) of the differential pressure control valve (7) also increases, and the differential pressure control valve (7)
The pressure difference between the upper pressure chamber (14) and the lower pressure chamber (15) also increases, but depending on the pressure difference at this stage, the diaphragm (12) is in the initial state without moving upward, and The valve (13) maintains the state where the outlet (7b) of the differential pressure control valve (7) is closed.

Thereafter, the flow rate of the gas further increases, and the data of the gas flow by the flow meter for large flow rate (10) becomes the second reference value (B) immediately before the differential pressure control valve (7) is driven. Then, a closing signal is transmitted from the control unit (11) to the electromagnetic valve (8), and as shown in FIG. 2C, the electromagnetic valve (8) receiving the closing signal closes the valve provided inside. Then
The differential pressure between the outlet (10a) of the mass flow meter (10) and the inlet (7a) of the differential pressure control valve (7) increases rapidly, and the upper pressure chamber (14) of the differential pressure control valve (7) increases. ) And the lower pressure chamber (15) also increase rapidly, so that the diaphragm (12) moves upward at a stretch, and accordingly the switching valve (13) moves the outlet of the differential pressure control valve (7). (7b) is opened stably. Therefore, the gas flows through the large flow gas pipe (6) through the differential pressure control valve (7), so that the gas flow is measured by the large flow gas pipe (6) and the control is performed. The flow rate data is transmitted to the unit (11) every two seconds, and the control unit (11) directly monitors the flow rate data of the large flow rate meter (10).

On the other hand, when the gas flow rate decreases and the flow rate data of the large flow rate meter (10) becomes the third reference value (C) immediately before the differential pressure control valve (7) is closed, the control unit (11)
The opening signal is transmitted from the controller to the solenoid valve (8), and as shown in FIG. 3B, the solenoid valve (8) receiving the opening signal opens the valve provided inside. Then, a large flow meter (1
0) and the differential pressure between the inlet (7a) of the differential pressure control valve (7) and the upper pressure chamber (14) and the lower pressure chamber of the differential pressure control valve (7). Since the differential pressure with (15) also decreases rapidly, the diaphragm (12) moves downward at a stretch and the switching valve (13) stabilizes the outlet (7b) of the differential pressure control valve (7). Close well. Therefore, the gas flows through the gas pipe for large flow (6) through the gas pipe for electromagnetic valve (4), so that the flow rate of the gas is measured by the flow meter for large flow (10). The flow rate data is transmitted to the control unit (11) every two seconds, and the control unit (11) directly monitors the flow rate data of the large flow rate flow meter (10).

Thereafter, when the gas flow rate further decreases and the gas flow rate data from the large flow rate flow meter (10) reaches the first reference value (A), the control section (11) sends a solenoid valve (8).
3A, the solenoid valve (8) that has received the close signal closes the valve provided inside, as shown in FIG. Therefore, the gas is supplied to the gas pipe for the differential pressure control valve (3).
Since the gas does not flow into any of the gas pipes of the solenoid valve gas pipe (4) and flows only through the small flow gas pipe (5), the flow rate of the gas is measured by the small flow meter (9). At the same time, the flow rate data is transmitted to the control section (11) every two seconds, and the flow rate data of the small flow rate flowmeter (9) is monitored by the control section (11) as it is.

As described above, the solenoid valve (8) opens and closes only when the flow rate is within a certain range of the first, second, and third reference values (A), (B), and (C). Is controlled, the solenoid valve (8) can be opened and closed with a small force, and power consumption can be suppressed.

Before the differential pressure control valve (7) opens and closes, the flow rate of the differential pressure control valve (7) changes greatly by controlling the opening and closing of the solenoid valve (8). Hunting of the pressure control valve (7) can be prevented.

When the flow rate of the gas flowing through the gas pipe for electromagnetic valve (4) or the gas pipe for small flow rate (5) suddenly increases, the differential pressure increases sharply, so that the differential pressure control valve (7) is opened. Correspond. In this case, the flow rate may be in the hunting area, but the operation returns to the normal operation in the measurement after 2 seconds, and the operation is stabilized.

[0031]

According to the first aspect of the present invention, there is provided a flow rate meter for a small flow rate, a differential pressure control valve that opens and closes by a differential pressure of a fluid,
An electromagnetic valve that opens and closes by the action of an electromagnetic force is provided in parallel with the small flow rate meter, the differential pressure control valve and the solenoid valve and the large flow rate flow meter are provided in series, and the electromagnetic valve is: It is controlled according to the flow rate measured by the flow meter for small flow rate or the flow meter for large flow rate, so the solenoid valve is opened and closed with a small force, power consumption can be kept low, and the differential pressure Before the control valve opens and closes, the opening and closing of the solenoid valve is controlled, so that the flow rate greatly changes, and hunting of the differential pressure control valve can be prevented.

According to the second aspect of the present invention, when the fluid has a flow rate (first reference value) optimum for switching between the small flow rate flow meter and the large flow rate flow meter, and the differential pressure When the flow rate value (the second and third reference values) becomes optimal for opening and closing the control valve, the solenoid valve opens and closes, so that the above-described suppression of power consumption and prevention of hunting can be reliably achieved.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing one embodiment of a flow meter according to the present invention.

FIG. 2 is an enlarged sectional view of the differential pressure control valve shown in FIG.

FIG. 3 is a diagram showing a transition according to a flow rate of the flow meter of FIG. 1;

FIG. 4 is a flowchart of a transition according to a flow rate of the flow meter of FIG. 1;

FIG. 5 is a diagram showing a flow meter using a conventional solenoid valve.

FIG. 6 is a diagram showing a flow meter using a conventional differential pressure control valve.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Casing 2 ... Gas pipe 3 ... Gas pipe for differential pressure control valves 4 ... Gas pipe for solenoid valves 5 ... Gas pipe for small flow rate 6 ... Gas pipe for large flow rate 7 ... Differential pressure control valve 8 ... Electromagnetic valve 9 ... Flow meter for small flow rate 10 ... Flow meter for large flow rate 12 ... Diaphragm 13 ... Switching valve 16 ... Connection pipe

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Takaomi Raft 4-1-2 Hirano-cho, Chuo-ku, Osaka-shi Inside Osaka Gas Co., Ltd. (72) Inventor Akio Kono 2- 10-16 Higashi-Kobashi, Higashi-Nari-ku, Osaka-shi Kansai Gas Meter Co., Ltd. (72) Inventor Tetsuya Yasuda 2-10-16 Higashikobashi, Higashinari-ku, Osaka City Kansai Gas Meter Co., Ltd. F-term (reference) 2F030 CC13 CD13 CE13 CF01 CF05 CF08

Claims (2)

[Claims] 1. A flow meter having a small flow rate meter for measuring a small flow rate fluid and a large flow rate flow meter for measuring a large flow rate fluid, wherein the small flow rate meter and a differential pressure of the fluid are used. A differential pressure control valve that opens and closes and a solenoid valve that opens and closes by the action of an electromagnetic force are provided in parallel, and the small flow rate meter, the differential pressure control valve, the solenoid valve, and the large flow rate meter are connected in series. And the electromagnetic valve is controlled in accordance with a flow rate measured by a small flow rate flow meter or a large flow rate flow meter. 2. When the flow rate data measured by the small flow rate meter becomes equal to or more than a first reference value which is an optimal flow value for switching between the small flow rate meter and the large flow rate meter, The solenoid valve closes when the solenoid valve is opened and the flow rate data measured by the large flow meter reaches or exceeds the second reference value, which is the optimal flow value for opening the differential pressure control valve. On the other hand, when the flow rate data measured by the large flow rate flow meter becomes equal to or less than the third reference value which is the optimum flow rate value for closing the differential pressure control valve, the solenoid valve is opened, The flowmeter according to claim 1, wherein the solenoid valve is closed when flow rate data measured by the large flow rate flowmeter becomes equal to or less than the first reference value.