JP7084225B2 - Flow measuring device - Google Patents

Description

The present invention relates to a flow rate measuring device.

Conventionally, a straight tube-shaped gas meter in which a gas inlet for introducing gas and a gas outlet for discharging gas are arranged in a straight line is known (see, for example, Patent Document 1). This straight tube type gas meter is provided with a shielding plate on the downstream side of the gas inflow port, and the gas introduced into the meter is diffused so as to collide with the shielding plate. Therefore, even if a gas having a biased flow enters the meter, it can be guided to the measurement flow path after breaking the flow, and an accurate gas flow velocity can be measured.

Japanese Unexamined Patent Publication No. 2017-125701

However, in the straight tube type gas meter described in Patent Document 1, since the gas inlet, the gas outlet, and the flow rate measuring unit having the flow velocity sensor and the measuring cylinder portion are arranged in a straight line, the linear direction (predetermined). It becomes a long shape in the direction). In particular, when a pressure regulator is attached to such a straight pipe type gas meter, the pressure regulator is located on the gas inlet side, and the pressure regulator becomes longer in the linear direction. Therefore, it is conceivable to shorten the measuring cylinder portion itself of the measuring unit to suppress the increase in size in a predetermined direction.

However, in a straight pipe type gas meter, although it is possible to form an internal gas flow path linearly in a predetermined direction, when a shutoff valve such as a motor valve or a solenoid valve is provided inside, the gas flow path is provided. It is necessary to bend the gas flow path by extending a part of the gas in a direction substantially orthogonal to a predetermined direction. For this reason, a drift is generated in the gas at this bent portion. Therefore, if the measuring cylinder portion itself is configured to be short, the gas enters the measurement unit without eliminating the drift, and the measurement accuracy is deteriorated. Will be invited.

It should be noted that this problem is not limited to the straight tube type gas meter, but is also common to, for example, a flow rate measuring device having no display unit for displaying the integrated flow rate.

The present invention has been made to solve such a conventional problem, and an object of the present invention is to be able to stabilize the measurement of gas flow velocity while reducing the size in a predetermined direction. The purpose is to provide a flow rate measuring device.

The flow rate measuring device of the present invention includes a gas flow path extending in a substantially predetermined direction from a gas inlet to a gas outlet, a flow velocity sensor, a measuring cylinder, and a isolation valve. The gas flow path extends in a direction substantially orthogonal to a predetermined direction on the upstream side of the measuring cylinder portion and is formed by extending in a predetermined direction from the bending flow path portion in which a shutoff valve is installed and the measuring cylinder portion. It is provided with a buffer flow path portion formed by surrounding the upstream end. The bent flow path portion has a bank portion protruding from the wall portion on the downstream side of the isolation valve toward the measuring cylinder portion in a cross section in a plane including both a predetermined direction and an extending direction of the bent flow path portion, and is a buffer. The flow path portion has a portion on the gas outlet side whose diameter is gradually increased from the gas inlet side to the gas outlet side .

According to the present invention, since the bent flow path portion has a bank portion protruding from the wall portion on the downstream side of the isolation valve toward the measuring cylinder portion, the gas passing through the bent flow path portion is caused by the bank portion of the measuring cylinder portion. It will be moved to the center side. As a result, the drift is suppressed and the gas easily flows into the measuring cylinder portion, and the length of the measuring cylinder portion can be shortened. Therefore, it is possible to stabilize the measurement of the gas flow velocity while reducing the size in a predetermined direction.

It is external perspective view of the straight tube type gas meter which concerns on this embodiment. It is sectional drawing which shows the outline of the internal structure of the straight pipe type gas meter which concerns on this embodiment. It is a graph which shows the relationship between the pressure fluctuation of a gas, and the measurement error of a flow rate. It is a graph which shows the variation of the instantaneous flow rate with respect to the flow rate. It is sectional drawing which shows the deformation example of the enlarged diameter part.

Hereinafter, the present invention will be described with reference to preferred embodiments. The present invention is not limited to the embodiments shown below, and can be appropriately modified without departing from the spirit of the present invention. Further, in the embodiments shown below, some parts of the configuration are not shown or explained, but the details of the omitted techniques are within the range where there is no contradiction with the contents described below. Needless to say, publicly known or well-known techniques are applied as appropriate.

FIG. 1 is an external perspective view of a straight tube type gas meter according to the present embodiment, and FIG. 2 is a cross-sectional view showing an outline of an internal configuration of the straight tube type gas meter according to the present embodiment. In the following description, a straight tube type gas meter will be described as an example of the flow rate measuring device, but the present invention is not limited to this.

The straight tube type gas meter 1 shown in FIGS. 1 and 2 includes a meter body (body) 10 which is a housing formed of a metal material such as aluminum or an aluminum alloy. The meter body 10 has a substantially square columnar outer shape, and has a straight tube shape that is longitudinal in the height direction of the square column. In the example shown in FIG. 1, the meter body 10 is installed so that its longitudinal direction coincides with the vertical direction, but the present invention is not limited to this, and the meter body 10 may be installed so that its longitudinal direction coincides with the horizontal direction.

The meter body 10 includes a gas inlet 11 for introducing gas into one end 10a in the longitudinal direction thereof, and a gas outlet 12 for discharging gas to the other end 10b in the longitudinal direction thereof. The gas inlet 11 is connected to a gas supply source via a pressure regulator (not shown) or an upstream pipe, and the gas outlet 12 is connected to a gas supply destination via a downstream pipe. The gas inlet 11 and the gas outlet 12 are arranged in a straight line along the longitudinal direction of the straight pipe. For the connection between the gas inlet 11 and the upstream pipe and the connection between the gas outlet 12 and the downstream pipe, for example, a joint structure 15 that can be disconnected by a one-touch operation (that is, only a pushing operation) is adopted. ..

Inside the meter body 10, one gas flow path 13 extending substantially in the longitudinal direction of the straight pipe (predetermined direction) is formed from the gas inlet 11 to the gas outlet 12. The gas flow path 13 has a bent structure having a bent flow path portion BP extending in a direction orthogonal to the longitudinal direction of the meter body 10 from the gas inflow port 11 to the gas outflow port 12.

Specifically, the gas flow path 13 is located on the gas inflow port 11 side and extends in the straight pipe longitudinal direction, and is located on the gas outflow port 12 side and extends in the straight pipe longitudinal direction. It has a second gas flow path 13b. The bent flow path portion BP is arranged between the first gas flow path 13a and the second gas flow path 13b and extends in the front-rear direction (direction orthogonal to the longitudinal direction of the straight pipe). Further, the gas flow path 13 has a buffer flow path portion BF formed so as to extend from the bent flow path portion BP in the longitudinal direction of the straight pipe.

Further, the straight pipe type gas meter 1 according to the present embodiment includes a display panel 2, a measuring unit 3, a isolation valve 6, and the like.

The display panel 2 is composed of an LCD (Liquid Crystal Display) or the like, and is provided on the front portion 10c of the meter body 10. The display panel 2 is controlled by a microcomputer (not shown) and displays information processed by the microcomputer. The typical information displayed on the display panel 2 is an integrated value (integrated flow rate) of the gas flow rate based on the measured value measured by the flow velocity sensor 5.

The measurement unit 3 shown in FIG. 2 includes a measurement cylinder unit 4 and a flow velocity sensor 5. The measuring cylinder portion 4 is a cylindrical body provided with the flow velocity sensor 5, and constitutes a part of the second gas flow path 13b. The measuring unit 3 integrally includes a plurality of straightening vanes (not shown) that divide the internal space inside the cylindrical body. The gas flowing through the measuring cylinder 4 is rectified by these straightening vanes. In the measuring cylinder portion 4, for example, the straightening vane is made of metal, and the others are made of resin or the like.

The flow velocity sensor 5 is attached to the front side of the measuring cylinder portion 4, and is housed in the protective case PC. The flow velocity sensor 5 includes an upstream sensor 5a and a downstream sensor 5b. The upstream side sensor 5a and the downstream side sensor 5b are arranged so as to be separated by a predetermined distance in the longitudinal direction of the straight pipe. Further, the upstream side sensor 5a and the downstream side sensor 5b are in an inclined state with respect to the gas flow direction Y (same as the straight pipe longitudinal direction). The microcomputer drives one of these sensors 5a and 5b to intermittently transmit an ultrasonic signal into the measuring cylinder 4 from the one. The transmitted ultrasonic signal is reflected by the wall on the rear side of the measuring cylinder 4, and is received by the other of the sensors 5a and 5b. The microcomputer causes the above operation to be performed from both the upstream side and the downstream side with respect to the gas flow direction Y, and calculates the gas flow velocity based on the difference in the propagation time of the ultrasonic signal regarding the transmission and reception. Further, the microcomputer measures the gas flow rate based on the calculated gas flow rate.

The above-mentioned rectifying plate is in a parallel relationship with the transmission / reception direction of the ultrasonic signal, and the rectifying plate is installed so as not to obstruct the transmission / reception of the ultrasonic signal.

The shutoff valve 6 shuts off the gas flow path 13 on the upstream side of the flow velocity sensor 5 (that is, the upstream side of the measuring cylinder portion 4) of the gas flow path 13, and is a bent flow path portion BP of the gas flow path 13. It is installed in. The isolation valve 6 protrudes in the orthogonal direction (extending direction of the bending flow path portion BP) to close the circular opening OP, and operates in the direction opposite to the protruding direction to open the circular opening OP. It is possible to transition between the open state and the open state.

Further, in the straight tube type gas meter 1 in the present embodiment, the measuring cylinder portion 4 is formed to be slightly shorter. Further, the buffer flow path portion BF is a flow path whose diameter has been expanded so as to surround the upstream end 4a of the measuring cylinder portion 4. Measures against pulsation of the gas flowing in by the expanded buffer flow path portion BF are taken. Since the buffer flow path portion BF is formed by surrounding the upstream end 4a of the measuring cylinder portion 4, the measuring cylinder portion 4 is in a state of floating from the rear wall 1a of the straight tube type gas meter 1.

In addition, the straight pipe type gas meter 1 according to the present embodiment has a bank portion BS in the bent flow path portion BP. The bank portion BS has a rear wall 1a (a wall portion on the downstream side of the isolation valve 6) in a cross section (that is, a cross section shown in FIG. 2) in a plane including both the longitudinal direction of the straight pipe and the extending direction of the bent flow path portion BP. ) To the measuring cylinder 4 side (that is, the front side).

In the present embodiment, since the buffer flow path portion BF surrounds the measuring cylinder portion 4, the measuring cylinder portion 4 is slightly floating from the rear wall 1a. That is, the measuring cylinder portion 4 is located on the front side of the rear wall 1a. Since such a measuring cylinder portion 4 is formed slightly shorter, it becomes difficult to rectify the gas as compared with the case where the measuring cylinder portion 4 is formed longer.

However, since the bent flow path portion BP is provided with a bank portion BS protruding from the rear wall 1a toward the measuring cylinder portion 4, the gas passing through the bent flow path portion BP is moved to the center side of the measuring cylinder portion 4 by the bank portion BS. It will be brought together. As a result, it becomes easy to introduce the gas into the measuring cylinder portion 4 in a state where the drift is suppressed, and the measurement can be stabilized even if the length of the measuring cylinder portion 4 is shortened.

Here, the bank portion BS projects toward the measuring cylinder portion 4 at a height equal to or lower than the center position CP of the measuring cylinder portion 4. Therefore, the height of the bank portion BS exceeds the center position CP of the measuring cylinder portion 4, and the situation where the gas flowing into the measuring cylinder portion 4 is disturbed due to the bank portion BS being too high is suppressed. There is.

Further, the measuring cylinder portion 4 constitutes a diameter-expanded portion E in which the upstream end 4a is larger than the central portion 4b, and the opening area of the diameter-expanded portion E is the opening area of the central portion 4b of the measuring cylinder portion 4. It is preferably 2.8 times or more. When the distance L from the upstream end of the buffer flow path portion BF to the enlarged diameter portion E of the measuring cylinder portion 4 is short (specifically, when the distance L is equal to or less than the front-rear distance of the buffer flow path portion BF), This is because the enlarged diameter portion E has an appropriate size and can suppress the variation in the instantaneous flow rate in the high flow rate range.

More specifically, the present inventor has found that the variation in the instantaneous flow rate depends on the length of the distance L and the opening area of the enlarged diameter portion E. Therefore, when the distance L is long, the variation in the instantaneous flow rate becomes small even if the opening area of the enlarged diameter portion E is less than 2.8 times the opening area of the central portion 4b of the measuring cylinder portion 4. However, when the distance L is short, the variation in the instantaneous flow rate can be suppressed by setting the opening area of the enlarged diameter portion E to 2.8 times or more the opening area of the central portion 4b of the measuring cylinder portion 4. In particular, since the straight pipe type gas meter 1 tends to be larger in the longitudinal direction of the straight pipe, if the opening area of the enlarged diameter portion E is 2.8 times or more the opening area of the central portion 4b of the measuring cylinder portion 4, The distance L can be shortened, and the increase in size in the longitudinal direction of the straight pipe can be suppressed.

From the viewpoint of suppressing the variation in the instantaneous flow rate, the opening area of the enlarged diameter portion E may be 2.8 times or more the opening area of the central portion 4b of the measuring cylinder portion 4 while increasing the distance L. This is because, although there is a concern that the size will increase to some extent, it is possible to more reliably suppress the variation in the instantaneous flow rate.

FIG. 3 is a graph showing the relationship between the pressure fluctuation of the gas and the measurement error of the flow rate. In FIG. 3, a case where the distance L is shortened will be described as an example. As shown in FIG. 3, it is required that the measurement error of the flow rate is about 1.1 L / h or less with respect to the pressure fluctuation of the gas. Here, in the measuring cylinder portion 4 having no enlarged diameter portion E, the measurement error becomes −1.0 L / h at a frequency of 11.66 Hz. Further, the measurement error becomes −0.9 L / h at a frequency of 50 Hz.

On the other hand, in the measuring cylinder portion 4 having the enlarged diameter portion E, the measurement error is −0.6 L / h at a frequency of 10 Hz, which is the maximum value (the maximum value in absolute value). Therefore, by providing the enlarged diameter portion E, it is possible to reduce the measurement error of the flow rate due to the pressure fluctuation, and it is possible to further stabilize the measurement.

FIG. 4 is a graph showing the variation of the instantaneous flow rate with respect to the flow rate. It should be noted that also in FIG. 4, the case where the distance L is shortened will be described as an example. As shown in FIG. 4, the variation in the instantaneous flow rate is small at 600 L / h to 9000 L / h regardless of whether or not the enlarged diameter portion E is provided. However, at 12000 L / h, there is a difference in the variation in the instantaneous flow rate, and in the measuring cylinder portion 4 which does not have the diameter-expanded portion E, a variation of less than 80 L / h occurs. On the other hand, in the measuring cylinder portion 4 having the enlarged diameter portion E and the opening area thereof being 2.8 times that of the central portion 4b, the variation at 12000 L / h is about 35 L / h. Further, in the measuring cylinder portion 4 in which the opening area of the enlarged diameter portion E is 3.5 times that of the central portion 4b, the variation at 12000 L / h is about 30 L / h. The flow rate correction coefficients used in calculating the flow rate are all within the range of 600 L / h to 12000 L / h within 1.05 to 1.07.

From FIGS. 3 and 4 above, the measuring cylinder portion 4 constitutes a diameter-expanded portion E in which the upstream end 4a is larger than the central portion 4b, and the opening area of the diameter-expanded portion E is the measuring cylinder portion 4. It can be said that it is preferable that the opening area of the central portion 4b of the above is 2.8 times or more.

Further, the straight tube type gas meter 1 according to the present embodiment includes a pressure sensor 7 as shown in FIG. The pressure sensor 7 detects the pressure of the gas flowing through the gas flow path 13. Generally, the pressure sensor 7 is provided in the gas flow path 13, but in the present embodiment, a small passage SR for connecting the gas flow path 13 and the pressure sensor 7 is formed in the meter body 10, and the gas is formed through the small passage SR. The pressure of the gas flowing through the flow path 13 is detected.

Specifically, the small passage SR is formed so as to connect from the wall portion on the upstream side of the circular opening OP of the bending passage portion BP to the pressure sensor 7. By using this small passage SR, it is possible to give a degree of freedom to the installation position of the pressure sensor 7. In the present embodiment, the installation area of the pressure sensor 7 and the installation area of the measuring cylinder portion 4 have a portion overlapping in the front-rear direction (an example of a direction orthogonal to a predetermined direction). That is, when visually recognized along the front-rear direction, at least a part of the pressure sensor 7 overlaps the measuring cylinder portion 4. As a result, it becomes difficult for the straight tube type gas meter 1 to increase in size in a predetermined direction, and it is possible to reduce the size.

Next, the operation of the straight tube type gas meter 1 according to the present embodiment will be described.

First, it is assumed that the gas appliance is used by the consumer. In this case, the gas introduced from the gas inlet 11 of the straight pipe type gas meter 1 reaches the bent flow path portion BP through the first gas flow path 13a, and the second gas from the bent flow path portion BP through the buffer flow path portion BF. It is introduced into the flow path 13b.

Here, when the gas passes through the bent flow path portion BP, the gap of the flow velocity distribution changes, and the flow velocity measurement by the flow velocity sensor 5 tends to become unstable due to the turbulence. However, the straight pipe type gas meter 1 according to the present embodiment has a bank portion BS on the rear wall 1a of the bending flow path portion BP. Moreover, the bank portion BS projects toward the measuring cylinder portion 4 at a height equal to or lower than the center position CP of the measuring cylinder portion 4. Therefore, the gas flow is directed toward the center side of the measuring cylinder portion 4. As a result, the gas flows into the measuring cylinder 4 while suppressing the drift.

Further, since the upstream end 4a of the measuring cylinder portion 4 has a diameter-expanded portion E having an opening area of 2.8 times or more the opening area of the central portion 4b, a high flow rate is provided despite the short distance L. Even when the gas of the above flows, there is little turbulence and it flows into the measuring cylinder portion 4.

Then, the gas introduced into the measuring cylinder portion 4 is rectified by the plurality of straightening vanes, and the flow velocity is measured by the flow velocity sensor 5. The straight pipe type gas meter 1 calculates the gas flow rate based on the measured flow velocity and displays the gas flow rate on the display panel 2 in an integrated manner.

In this way, according to the straight pipe type gas meter 1 according to the present embodiment, since the bent flow path portion BP has a bank portion BS protruding from the rear wall 1a toward the measuring cylinder portion 4, the bent flow path portion BP The gas passing through is brought to the center side of the measuring cylinder portion 4 by the bank portion BS. As a result, the drift is suppressed and the gas easily flows into the measuring cylinder portion 4, and the length of the measuring cylinder portion 4 can be shortened. Therefore, it is possible to stabilize the measurement of the gas flow velocity while reducing the size in the longitudinal direction of the straight pipe.

Further, since the bank portion BS protrudes at a height equal to or lower than the center position CP of the measuring cylinder portion 4 when visually recognized along the longitudinal direction of the straight pipe, the height of the bank portion BS is the center position of the measuring cylinder portion 4. It is possible to suppress a situation in which the gas flowing into the measuring cylinder 4 is disturbed due to exceeding the CP and the bank being too high.

Further, since the opening area of the enlarged diameter portion E of the measuring cylinder portion 4 is 2.8 times or more the opening area of the central portion 4b of the measuring cylinder portion 4, the diameter is expanded even when the distance L is short. The portion E has an appropriate size, and the variation in the instantaneous flow rate in the high flow rate range can be suppressed.

Further, since the installation positions of the measuring cylinder portion 4 and the pressure sensor 7 overlap in the front-rear direction, it is difficult to increase the size in the longitudinal direction of the straight pipe by providing the pressure sensor 7, and the size can be reduced.

Although the present invention has been described above based on the embodiments, the present invention is not limited to the above embodiments, and changes may be made without departing from the spirit of the present invention, and other examples may be made as appropriate. Techniques may be combined.

For example, in the above embodiment, the isolation valve 6 has been described assuming a motor valve or a solenoid valve, but the description is not limited to this, and other types of valves may be used. Further, in the present embodiment, the ultrasonic flow velocity sensor is provided as the flow velocity sensor 5, but if possible, another type of sensor such as a flow sensor may be used.

Further, in the present embodiment, the bank portion BS is assumed to be a solid member provided so as to project from the rear wall 1a, but the present invention is not limited to this, and a hollow member may be used. Further, the bank portion BS is preferably provided so as to project from substantially the entire rear wall 1a of the bent flow path portion BP, but is not limited to this, and is provided so as to project from a part of the rear wall 1a of the bent flow path portion BP. It may have been.

Further, the upper surface of the bank portion BS is preferably a flat surface extending in the longitudinal direction of the straight pipe, but the upper surface is not limited to this, and for example, the upper surface may be stepped or an inclined surface inclined in the longitudinal direction of the straight pipe. It may be.

Further, the pressure sensor 7 overlaps the measuring cylinder portion 4 in the front-rear direction and the installation area, but is not limited to this, and the pressure sensor 7 may overlap in the direction orthogonal to the longitudinal direction of the straight pipe, for example, in the left-right direction. For example, it does not ask the direction of overlap.

Further, the enlarged diameter portion E of the upstream end 4a of the measuring cylinder portion 4 is not limited to the trumpet shape shown in FIG. 2, but may be a nozzle shape shown in FIG. That is, as shown in FIG. 5, the upstream end 4a of the measuring cylinder portion 4 may be configured by the diameter-expanded portion E whose diameter is linearly expanded. This is because the same effect can be obtained. Further, the shape is not limited to the trumpet shape or the nozzle shape, and any other shape may be used as long as the enlarged diameter portion E is formed.

1: Straight tube type gas meter (flow rate measuring device)
1a: Rear wall (wall on the downstream side of the isolation valve)
4: Measuring cylinder part 4a: Upstream end 4b: Central part 5: Flow velocity sensor 6: Isolation valve 7: Pressure sensor 10: Meter body (body)
11: Gas inflow port 12: Gas outflow port 13: Gas flow path BF: Buffer flow path part BP: Bending flow path part BS: Bank part CP: Center position E: Diameter expansion part SR: Small passage

Claims (3)

A gas inlet and a gas outlet formed in the body for introducing gas and a gas outlet for discharging gas, a gas flow path extending in a substantially predetermined direction from the gas inlet to the gas outlet, and a gas flowing through the gas flow path. It is a flow rate measuring device provided with a flow velocity sensor for measuring the flow velocity of the gas flow path, and a measuring cylinder portion provided with the flow velocity sensor and forming a part of the gas flow path.
A shutoff valve for shutting off the gas flow path is provided on the upstream side of the flow velocity sensor.
The gas flow path extends in a direction substantially orthogonal to the predetermined direction on the upstream side of the measuring cylinder portion, and extends in the predetermined direction from the bending flow path portion in which the isolation valve is installed and the bending flow path portion. It is provided with a buffer flow path portion that is formed and is formed by surrounding the upstream end of the measuring cylinder portion.
The bent flow path portion is a bank portion that protrudes from the wall portion on the downstream side of the isolation valve toward the measuring cylinder portion in a cross section in a plane including both the predetermined direction and the extending direction of the bent flow path portion. Have,
The buffer flow path portion has a portion on the gas outlet side whose diameter is gradually increased from the gas inlet side to the gas outlet side.
A flow measuring device characterized by the fact that. The flow rate measuring device according to claim 1, wherein the bank portion projects toward the measuring cylinder portion at a height equal to or lower than the center position of the measuring cylinder portion. A pressure sensor that detects the pressure of the gas flowing through the gas flow path,
A small passage connecting the gas flow path and the pressure sensor is further provided.
The flow rate measuring device according to claim 1 or 2, wherein the installation position of the measuring cylinder portion and the pressure sensor has a portion overlapping in a direction orthogonal to the predetermined direction.

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