JPH0799340B2 - Fluid 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 provided at the boundary in a direction substantially perpendicular to the ejection direction of the ejection nozzle, and
A measurement part formed so as to face each other and having a pair of return flow paths connecting the control nozzles and the downstream side of the conduit expansion part, that is, the jet flow from the ejection nozzle connected to the conduit contraction part Utilizing the phenomenon of being stable in a state along one inclined surface of the expanded passage portion, and jetting fluid from the control nozzle alternately causes the jet flow from the injection nozzle to alternate along both inclined surfaces of the expanded passage portion. By utilizing the phenomenon of flow, two measuring units configured to measure the flow rate based on the change in the fluid frequency caused by the change in the flow direction of the jet from the jet nozzle are connected in series, and the measuring units are connected in series. Of these, the first ejection nozzle is formed to have an opening area smaller than that of the second ejection nozzle, a bypass flow path that bypasses the first measurement unit is connected to the second measurement unit, and the bypass is provided. In the flow path,
The present invention relates to a fluidic flow meter provided with an automatic opening / closing valve that opens at a large flow rate and closes at a small flow rate.

[Conventional technology]

The above-mentioned flowmeter was previously proposed in Japanese Patent Application No. 60-66345 and Japanese Patent Application No. 160-160820 as a device that can always measure the flow rate with high accuracy regardless of a large change in the flow rate. It was configured as shown in the figure.

In other words, when the flow rate gradually increases from zero, the valve body (44) initially has a small differential pressure (P ₁ −P ₂ ), so
In 5), the fluid is fully closed, the fluid flows from the second measuring section (B) to the first measuring section (A), and the flow direction change of the fluid ejected from the ejection nozzle in the first measuring section (A) changes. Is detected by a pressure or flow rate change detection sensor in the return flow path, and the flow rate is calculated and displayed based on information from the sensor. Then, when the differential pressure (P ₁ -P ₂ ) becomes equal to or higher than the set value, the valve body (44) is opened, and the flow direction change of the ejected fluid from the ejection nozzle in the second measurement section (B) changes in the return flow path. The pressure or the flow rate is detected by a sensor for detecting the flow rate, and the flow rate is calculated and displayed based on the information from the sensor.

[Problems to be solved by the invention]

However, the range that can measure the flow rate accurately based on the information from the sensor is about 10 to 3,000 / h, and it was impossible to measure the minute flow rate less than 10 / h accurately. Therefore, in order to cover from the pilot fire to the maximum flow rate, 3 ~ 3,000
It is still insufficient as a household gas meter that requires accurate measurement of / h, and even if leakage occurs at a flow rate of about 3 / h or less on the downstream side of the flow meter when fluid transportation is stopped, flow rate measurement It was impossible to detect the leak from the information from the sensor.

An object of the present invention is to enable a minute flow rate to be accurately measured based on information from a flow rate measurement sensor.

[Means for solving problems]

A characteristic configuration of the present invention is that a low differential pressure actuation type on-off valve is provided at the inlet of the first measurement unit having a small ejection nozzle among the measurement units connected in series, and the inside of the case is formed to form the on-off valve. Two
By providing a dividing diaphragm, the upstream pressure chamber, and
A downstream pressure chamber connected to the first measuring unit is formed in the case, and a first spring for urging the diaphragm toward the upstream pressure chamber is provided to connect the upstream pressure chamber and the downstream pressure chamber. A second spring that attaches a communicating valve seat to the diaphragm, arranges a valve body that opens and closes an opening of the valve seat on the upstream side of the valve seat, and causes the valve body to contact the valve seat and follow it. And a valve-opening stopper that prevents the valve body from following the valve seat when the pressure in the downstream pressure chamber becomes lower than the upstream pressure chamber by a set value or more. On the street.

[Work]

As shown in FIGS. 1 and 4, the first measurement is performed when the automatic opening / closing valve (C) of the bypass flow path (15) for the first measuring section (A) is closed and the flow rate is small or the fluid supply is stopped. In the low differential pressure actuation type on-off valve (D) provided in the portion (A), the diaphragm (29) moves to the first position as the downstream pressure chamber (35) becomes lower in pressure than the upstream pressure chamber (33). The valve body (38) moves to the downstream pressure chamber (35) against the first spring (37), and the valve body (38) is attached to the diaphragm (29) by the second spring (39) with respect to the valve seat (36). When the pressure chamber (35) moves lower while the pressure chamber (33) becomes lower than the upstream pressure chamber (33), the valve body (38) moves due to the action of the valve opening stopper (40). Diaphragm, then diaphragm (29)
Along with the movement of the valve seat (36) and the valve seat (36), the opening of the valve seat (36) is opened, and the fluid from the upstream pressure chamber (33) flows into the downstream pressure chamber (3
It is supplied from 5) to the first measuring section (A).

Then, as the fluid flows from the upstream pressure chamber (33) into the downstream pressure chamber (35), the pressure in the downstream pressure chamber (35) instantaneously rises, and as shown in FIG. Springs (37)
The diaphragm (29) and the valve seat (36) move toward the upstream pressure chamber (33) by the action of, and the valve seat (36) is closed by the valve body (38), and the valve body (38) is also the second. The valve seat (36) moves against the spring (39) to cut off the fluid supply to the first measuring section (A).

Then, with the outflow of the fluid on the downstream side of the first measuring section (A), the pressure chamber (35) on the downstream side of the pressure chamber (33) on the downstream side is again detected.
Becomes low, the above-mentioned low differential pressure actuation type open / close valve (D) is opened and closed, and as shown by the solid line in FIG. 5, the first valve is intermittently and in a short time (Δt). The fluid is supplied to the measuring unit (A) of

Accordingly, the first measuring portion is even with the same micro-flow, continuously flow as indicated by a dotted line in FIG. 5 (Q ₁₎ (A)
According to the present invention, the apparent flow rate (Q ₂ ) becomes extremely large as compared with the conventional technology for supplying fluid to the, and a minute flow rate of 10 / h or less, which cannot be accurately measured by the conventional technology. It became possible to measure accurately.

〔The invention's effect〕

As a result, it can be put to practical use as a household gas meter that requires accurate measurement of 3 to 3,000 / h, and the leak detection that requires accurate measurement of 3 / h or less can be effectively used with a fluidic flow meter. It has become possible to carry out it with sufficiently simple and inexpensive equipment as compared with the case where a separate leak detecting means is separately provided.

〔Example〕

 Next, an embodiment will be described with reference to FIGS.

As shown in FIGS. 1 and 2, a small flow path (13) having a small opening area is provided by a partition wall (9) on the downstream side in the pipe (1).
And a bypass flow path (15) having a large opening area are formed by division, and a small flow path (13) is provided with a first measurement unit (A) described later,
A second measuring unit (B) described below is provided upstream of the small flow path (13) and the bypass flow path (15), and a diaphragm governor valve (C) for opening and closing the bypass flow path (15) is provided. .

The measurement units (A) and (B) have the same configuration and are configured as follows.

The pair of first flow path forming members (4a), (4b) forming the duct reduction part (2) and the jet nozzle (3) are arranged symmetrically with respect to the central axis, and the duct reduction part ( By the action of 2), the fluid is smoothly guided to the ejection nozzle (3), and at the same time, the ejection nozzle (3)
Is configured to eject the fluid substantially parallel to the central axis from the pipe, and the expanded pipe section (5) and the pair of control nozzles (6
a), (6b), and a pair forming a pair of return flow passages (7a), (7b) for communicating the control nozzles (6a), (6b) with the downstream side of the conduit expansion part (5), respectively. Partition walls (8a), (8b)
Are arranged symmetrically with respect to the central axis, and a pair of control nozzles (6a) and (6b) are installed between the ejection nozzle (3) and the conduit expanding portion (5). A state in which the partition wall (17) forming a pair of discharge passages (16a) and (16b) is directed to a direction substantially perpendicular to the ejection direction and opposed to each other, and blocks the downstream side of the conduit enlargement portion (5). The discharge paths (16a) and (16b) are separately connected to the inlet sides of the return flow paths (7a) and (7b).

That is, when the ejection of the fluid from the ejection nozzle (3) is started, the ejected fluid is discharged to one of the partition walls (8a) by the Coanda effect.
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 flows along the partition wall (8b) on the opposite side. Flow, and the fluid energy from the control nozzle (6b) on the opposite side in turn causes the jetted fluid to flow again along the partition wall (8a) along which the jet nozzle (6b) was initially arranged, thus, the jet nozzle (3). Fluid from the bulkhead (8
A) and (8b) are arranged alternately so that the jet flow direction changes in a shorter period as the jet fluid volume increases and in a state of quantitative correlation. is there.

A target (14) is provided on the downstream side of the pipe expanding portion (5) so that the change in the flow direction of the jetted fluid is further stabilized.

The opening area of the jet nozzle (3) of the first measuring section (A) is smaller than the opening area of the jet nozzle (3) of the second measuring section (B) by, for example, 1/28. Has become
The correlation between the flow rate and the ejection fluid flow direction change frequency should be good in the first measuring section (A) in the small flow rate range and in the second measuring section (B) in the large flow rate range. Configured.

Pipes (18a) and (18b), which are respectively communicated with the reversing flow sections at the inlets of both return flow paths (7a) and (7b), are connected to a closed case (19) arranged in the pipe (1), The pressure sensor (20) is installed in the sealed case (19) so that the fluid pressures from both pipes (18a) and (18b) act in opposite directions, and based on the information from both sensors (10), A flow rate display device (11) that calculates and displays the flow rate from the frequency of pressure change is provided.
Therefore, a feedback type fluidic flow meter is constructed.

The governor valve (C) is to open the upstream pressure (P ₁₎ and the differential pressure of the downstream pressure _{(P 2) (P 1 -P} 2) only when the above configuration, the following configuration is there.

As shown in FIG. 1, a first diaphragm (21) that divides the inside of the case (X) into two is provided on the downstream side of the valve seat (20) provided in the bypass flow path (15), and the second measurement is performed. Inside the case (X), there are a first pressure chamber (23) communicating with the upstream side of the section (B) through a passage (22) and a second pressure chamber (24) also serving as a downstream side flow passage of the valve seat (20). A valve body (25) for opening and closing the opening of the valve seat (20) is arranged on the upstream side of the valve seat (20), and the pressed plate (27) is attached to the rod (26) attached to the valve body (25). ) Is attached, and a spring (28) for urging the valve body (25) to close is provided between the pressed member (27) and the valve seat (20), and the pressed member (27) is It is placed close to the diaphragm (21).

That is, as shown in FIG. 3, when the flow rate is large, the pressure (P ₂ ) in the second pressure chamber (24) decreases, and the pressure difference between the first pressure chamber (23) and the second pressure chamber (24) ( P ₁ and -P ₂₎ is equal to or greater than the set,
The pressed member (27) is pressed and moved against the spring (28) by the first diaphragm (21), and the valve body (25).
As shown in FIGS. 1 and 4, when the flow rate is small or the fluid supply is stopped, the differential pressure (P ₁ -P ₂ ) between the first pressure chamber (23) and the second pressure chamber (24) is ) Becomes smaller and the valve body (25) is closed by the spring (28).

As shown in FIG. 1, a low differential pressure actuation type opening / closing valve (D) is provided at the inlet of the first measuring unit (A), and the downstream side pressure of the opening / closing valve (D) is set to a set value ( The on-off valve (D) is configured as follows so that the valve is opened only when it becomes lower by about 10 mm H ₂ O or less).

Second diaphragm (29) that divides the inside of the case (Y) into two
And an upstream pressure chamber (33) connected to the downstream side of the second measurement section (B) by the flow path (20), and connected to the first measurement section (A) by the flow path (34). Downstream pressure chamber (35)
Is formed in the case (Y), and a valve seat (36) that connects the upstream and downstream pressure chambers (33) and (35) to each other is attached to the second diaphragm (29). A valve that opens and closes the opening of the valve seat (36) by providing a first spring (37) that urges the second diaphragm (29) toward the upstream pressure chamber (33) between the two diaphragms (29). The body (38) is arranged on the upstream side of the valve seat (36), and the valve body (38) is brought into contact with the valve seat (36) and follows the movement between the valve body (38) and the case (Y). A second spring (39) is provided to allow the downstream pressure chamber (35) to have a lower pressure than the upstream pressure chamber (33) by a set value or more, and the downstream pressure chamber (35) with respect to the valve seat (36) of the valve body (38). ) Is attached to the case (Y) with a valve-opening stopper (40) that prevents the follow-up movement toward ().

That is, as shown in FIG. 4, when the governor valve (C) of the bypass flow passage (15) is closed and the pressure in the downstream side pressure chamber (35) becomes lower than that in the upstream side pressure chamber (33), Spring (3
The second diaphragm (29) moves toward the downstream pressure chamber (35) against 7) and the second spring (39) causes the valve body (38) to follow the valve seat (36). If the pressure in the downstream pressure chamber (35) becomes lower than the set value by more than the pressure in the upstream pressure chamber (33), the valve element (3
The movement of 8) is blocked, the opening of the valve seat (36) is opened,
The fluid in the upstream pressure chamber (33) is sent from the downstream pressure chamber (35) to the first measuring section (A).

Then, as the fluid flows from the upstream pressure chamber (33) into the downstream pressure chamber (35), the pressure in the downstream pressure chamber (35) instantaneously rises, and as shown in FIG. 2nd diaphragm (29) and valve seat (36) by 1 spring (37)
Moves toward the upstream pressure chamber (33), the valve seat (36) is closed by the valve body (38), and the fluid supply to the first measurement unit (A) is cut off. Therefore, as indicated by the solid line in FIG. 5, the fluid is supplied to the first measuring section (A) in a short time (Δt) and in a state where the apparent flow rate (Q ₂ ) is large and the minute flow rate is The measurement unit (A) of No. 1 can accurately measure.

The flow rate display device (11) has means (11a) for judging whether or not the frequency in the first information from the sensor (10) of the second measuring section (B) is equal to or lower than the setting, and its judging means ( 11
According to the instruction from a), when the frequency of the first information is less than or equal to the setting, the second value from the sensor (10) of the first measuring unit (A)
Based on the information, and based on the first information when the frequency of the first information exceeds a set value, means (11b) for calculating the flow rate, and means (11c) for displaying the calculated flow rate, For example, in a wide range from 3 / h or less to 3,000 / h, accurate measurement can be performed while suppressing the differential pressure to 15 mm H ₂ O or less.

Further, the set frequency in the measuring means (11a) is set to an approximately intermediate value between the minimum frequency in the first information and the frequency corresponding to the opening time of the governor valve (C), and the flow rate is measured by the first information. Can be performed in a state where there is no or very little error due to linearity deterioration in the correlation between the flow rate and the frequency, and a measurement error due to opening of the governor valve (C) does not occur. That is, the flow rate is calculated from the first information before the governor valve (C) is opened, and conversely, when the governor valve (C) is closed, the frequency of opening and the minimum frequency of the first information are calculated. When the frequency becomes equal to or lower than the intermediate frequency, the flow rate is calculated by the second information.

A timer switch (41), which is operated according to the movement of the second diaphragm (29) of the opening / closing valve (D), is attached to the case (Y), and a timer (43) for operating the power switch of the flow rate display device (11). The timer switch (41) is connected to, the timer switch (41) is turned on and off by the separation of the second diaphragm (29), and each time the timer switch (41) is turned on and off, the power switch is turned on by the timer (43). The flow rate display device (11) is kept powered for a set time, so that the power supply switch of the flow rate display device (11) is kept in the ON state when the fluid is supplied, and the power is supplied to the flow rate display device (11) when the fluid supply is stopped. The circuit is cut so that power can be saved.

[Another embodiment]

 Next, another embodiment will be described.

Instead of the governor valve (C), an electromagnetic valve that is opened at a large flow rate and closed at a small flow rate based on information from the computing means (11b) may be provided, and they are collectively called an automatic opening / closing valve (C). .

In order to connect the two measuring units (A) and (B) in series, the first measuring unit (A) with a small ejection nozzle (3) is connected to the second measuring unit (B) with a large ejection nozzle (3). ) May be arranged upstream.

The detection method, the configuration, the number of installed sensors, etc. of the sensor (10) can be freely changed. For example, one of the return flow paths (7a) or (7b) may be provided with a pressure or flow rate detection sensor (10). Also, the device (11) for detecting and displaying the flow rate can be changed in various ways.

The flow meter is used mainly 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]

1 to 4 show an embodiment of the present invention, FIG. 1 is an overall sectional view, FIG. 2 is a sectional view taken along line II-II of FIG. 1, and FIG. 3 and FIG. The cross-sectional view and FIG. 5 are graphs showing changes in the flow rate. FIG. 6 is a sectional view 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, (15) ... bypass flow path,
(29) …… diaphragm, (33) …… upstream pressure chamber,
(35) …… Downstream pressure chamber, (36) …… Valve seat, (37) ……
1st spring, (38) ... valve element, (39) ... second spring, (40) ... valve opening stopper, (A) ... first
(B) ... second measuring section, (C) ... automatic on-off valve, (D) ... low differential pressure actuated on-off valve, (Y) ... case.

Claims (1)

[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 measuring section (A) having a pair of return flow paths (7a), (7b) connecting the downstream sides of the conduit expanding section (5), respectively.
The two of (B) are connected in series, and the first of those measuring units is connected.
(A) the jet nozzle (3) having a smaller opening area than the jet nozzle (3) of the second nozzle (B) and bypassing the first measuring section (A). A feedback-type fluidic fluid which has a passage (15) connected to the second measuring section (B), and an bypass valve (15) provided with an automatic opening / closing valve (C) which opens at a large flow rate and closes at a small flow rate. In the flow meter, a low differential pressure actuation type opening / closing valve (D) is provided at the inlet of the first measuring unit (A), and the inside of the case (Y) is divided into two to form the opening / closing valve (D). Diaphragm to divide (2
9) is provided to form an upstream pressure chamber (33) and a downstream pressure chamber (35) connected to the first measuring section (A) in the case (Y), and the diaphragm (29). ) Is provided to the upstream pressure chamber (33) side, and a valve seat (36) that connects the upstream and downstream pressure chambers (33) and (35) is provided with the first spring (37). A valve body (38) which is attached to the diaphragm (29) and opens and closes the opening of the valve seat (36) is arranged upstream of the valve seat (36), and the valve body (38) is arranged in the valve seat (36). A second spring (39) that makes contact with and follows the valve is provided, and when the pressure in the downstream pressure chamber (35) becomes lower than the upstream pressure chamber (33) by a set value or more, the valve of the valve element (38) A fluidic flow meter provided with a valve opening stopper (40) for preventing follow-up movement to the seat (36).