JP2009186429A - Gas meter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the measurement accuracy of a flow rate more than the past case, by straightening the gas flow flowing into a measurement pipe from a flow channel member to some extent. <P>SOLUTION: This gas meter 10 is provided with straightening plates 36, 38 arranged in the vicinity of an inflow port 12 of the measurement pipe 40 to block the gas flow channel formed by the flow channel member 22 and guide and straighten the gas flowing in the flow channel member 22 to channel holes 36b, 38b formed at predetermined locations. Since the channel hole 36b is formed at the predetermined location of the straightening plate 36, the gas flowing in the flow channel member 22 is guided and straightened. According to such a straightening, the gas can easily flow toward the inflow port of the measurement pipe 40 from the channel hole 36b. In other words, collision to the measurement pipe 40 is restrained when the gas flows into the measurement pipe 40 from the flow channel member 22. Accordingly, since the flow of the gas, flowing into the measurement pipe 40 from the flow channel member 22, can be straightened, to some extent, and as a result, the measurement accuracy of the flow rate can be improved better than the past case. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a gas meter including a flow path member, a measurement tube, an ultrasonic wave propagation unit, and a flow rate calculation unit.

The gas meter, for example, utilizes the fact that the propagation time or propagation speed of ultrasonic waves changes depending on the flow velocity of the gas (measuring fluid), and propagates the ultrasonic waves to the gas flowing in the measurement pipe (conduction path) to reduce the gas flow rate. Measuring. When measuring the flow rate, if the aspect of the gas flow in the measuring tube changes significantly, the measurement error tends to increase. Conventionally, in order to improve measurement accuracy, an example of a technique in which a rectifying plate that is divided into a plurality of layers so that the thickness (height in the stacking direction) is uniform is provided in a measurement tube (for example, Patent Document 1). See).
JP 2006-64626 A

  In the gas meter described in Patent Document 1, a measurement pipe is provided in the middle of a flow path member serving as a gas flow path from the inlet to the outlet, so that the gas flowing from the flow path member into the measurement pipe is the measurement pipe. It is disturbed by hitting. Even if the flow of turbulent gas is to be adjusted with only the rectifying plate, there is a limit to the distance that can be secured from the inlet of the measuring tube to the end of the rectifying plate. ) Is a little present.

  The present invention has been made in view of the above points, and an object thereof is to provide a gas meter with higher flow rate measurement accuracy than before by adjusting the flow of gas flowing from a flow path member into a measurement tube to some extent. And

(1) Means for solving the problem (hereinafter simply referred to as “solution means”) 1 is as described in claim 1.
According to the solution 1, the rectifying plate is disposed in the vicinity of the inlet of the measurement tube so as to block the gas flow path formed by the flow path member. Since a passage hole is provided at a predetermined position of the rectifying plate, the gas flowing in the flow path member is guided and rectified. This rectification facilitates the flow of gas from the passage hole toward the inlet of the measuring tube. In other words, hitting the measurement tube when flowing from the flow path member to the measurement tube is suppressed. Thus, the flow of gas flowing from the flow path member to the measuring tube can be adjusted to some extent, and as a result, the flow rate measurement accuracy can be improved as compared with the conventional case.

(2) Solution 2 is as described in claim 2.
According to the solution 2, the rectifying plate is disposed not only in the vicinity of the inlet of the measurement pipe but also in the vicinity of the outlet of the measurement pipe so as to block the gas flow path formed by the flow path member. With this arrangement, the gas flow can be adjusted to some extent also on the outflow side, and as a result, the measurement accuracy of the flow rate is further increased.

(3) The solving means 3 is as described in claim 3.
According to the solution 3, the rectifying plate is provided with a rib that is erected from the periphery of the passage hole. Since the rib has a predetermined height, the flow of gas flowing from the flow path member to the measuring tube can be adjusted to some extent. Therefore, as a result, the measurement accuracy of the flow rate can be improved as compared with the conventional case.

  According to the present invention, since the flow of gas flowing from the flow path member into the measurement tube can be adjusted to some extent, the measurement accuracy of the flow rate can be improved as compared with the prior art.

  The best mode for carrying out the present invention will be described with reference to FIGS. FIG. 1 shows a front view of the gas meter according to the present invention, and FIG. 2 shows a plan view (top view). FIG. 3 is an exploded perspective view showing a configuration example of the gas meter. 4 represents a cross-sectional view taken along the line IV-IV in FIG. FIG. 5 shows a cross-sectional view taken along line VV in FIG. 6 represents a cross-sectional view taken along line VI-VI in FIG. FIG. 7 is a graph showing the relationship between the flow rate and the flow rate coefficient.

  First, an appearance example of the gas meter 10 will be briefly described with reference to FIGS. 1 and 2. 1 and 2, a gas meter 10 formed in a substantially rectangular box shape is provided with a front panel member 16 on the front side. The front panel member 16 is provided with a return button 18, a display means 20, and the like. The return button 18 returns the shut-off valve 34 (see FIG. 3) that has been activated by abnormality detection to return from the shut-off state to the flow state. For example, a liquid crystal display, an LED display, or the like is used as the display means 20, and displays the integrated value of the measured gas flow rate, other information, and the like.

  As shown in FIG. 3, the gas meter 10 includes a front panel member 16, a control board 26, a power pack 28, a pressure sensor 30, and an ultrasonic wave propagation means 32 (that is, a pair of ultrasonic wave propagation devices 32 a, around the flow path member 22. 32b), current plate 36, 38, measuring tube 40, bottom panel member 42, and the like. The flow path member 22 is integrally formed by, for example, aluminum die casting, and appears on the upper surface and the left and right side surfaces in the appearance of the gas meter 10. The flow path member 22 forms a cylindrical, substantially U-shaped flow path in which the inflow port 12 and the outflow port 14 are arranged on the same surface (upper surface in this example). That is, the flow path of the gas flowing in from the inlet 12 and flowing out of the outlet 14 together with other members (for example, the front panel member 16, the back panel member 24 and the bottom panel member 42 described later) is substantially U-shaped. Become a shape.

  By the way, when the entire substantially cylindrical U-shape is integrally formed with only the flow path member, a part or member (hereinafter simply referred to as “part etc.”) can be attached to or removed from the cylinder. It becomes difficult. Therefore, the flow path member 22 is integrally formed by opening the bottom portion, and after attaching parts and the like from the bottom portion (that is, the opening portion), the bottom panel member 42 is used to cover (FIG. 3, FIG. 3). (See FIG. 4). With such a configuration, it is easy to attach or remove components or the like in the cylinder while the gas flow path is substantially U-shaped in a cylindrical shape.

  Various parts and the like are attached to the flow path member 22 configured as described above. In FIG. 3, the mounting directions of the components and the like are indicated by arrows. The front panel member 16, the control board 26, the power pack 28, the pressure sensor 30, the ultrasonic wave propagator 32a, and the like are attached to the flow path member 22 from the front side (left side in the drawing). The control board 26 (corresponding to “control means”) includes electronic control components such as a CPU and a memory, and controls the entire gas meter 10. As an example of the control, the flow rate of the gas flowing through the measuring tube 40 is calculated based on the detection signals output from the ultrasonic wave propagators 32a and 32b, and the calculated flow rate of the gas is displayed on the display means 20. As another control example, various abnormality determinations are performed based on the pressure output from the detection signal of the pressure sensor 30, and when the abnormality is determined, a drive signal is output to the shutoff valve 34 to block the flow path. .

  The power pack 28 is used as a power source for driving the control board 26 and other electronic components. The power pack 28 is attached to a space K provided in the substantially central portion of the flow path member 22. The pressure sensor 30 is used to detect various abnormalities, detects the pressure of the gas in the flow path, and outputs a detection signal. The pressure sensor 30 is attached to a dedicated attachment hole provided on the front side of the substantially U-shaped flow path of the flow path member 22. The ultrasonic wave propagation device 32 a constitutes one side of the ultrasonic wave propagation means 32.

  The shut-off valve 34, the ultrasonic wave propagator 32b, the back panel member 24, and the like are attached to the flow path member 22 from the back side (right side of the drawing). The shutoff valve 34 closes (shuts down) the flow path when an abnormality is detected, so that gas does not flow to the outlet 14. The shut-off valve 34 is attached to a dedicated attachment hole provided on the back side of the substantially U-shaped flow path of the flow path member 22. The ultrasonic wave propagation device 32 b constitutes the other side of the ultrasonic wave propagation means 32. The back panel member 24 is provided on the back side of the gas meter 10.

  The rectifying plates 36, 38, the measuring tube 40, the bottom panel member 42, and the like are attached to the flow path member 22 from the bottom surface side (the lower side in the drawing). As shown in FIGS. 4 and 5, the rectifying plate 36 regulates the flow of the gas flowing in from the inflow port 12 to some extent and guides it to the inflow port of the measuring tube 40. The rectifying plate 36 has a passage hole 36b and a rib 36a. The passage hole 36b is formed in, for example, a rectangular shape in accordance with the shape of the inlet of the measuring tube 40 (see FIG. 6). The rib 36a rises from the peripheral edge of the passage hole 36b toward the inlet 12 and has a predetermined height. As shown in FIG. 4, the rectifying plate 38 regulates the flow of the gas flowing out from the outlet of the measuring tube 40 to some extent and guides it to the outlet 14. This baffle plate 38 has a passage hole 38b and a rib 38a. The passage hole 38b is formed in the same shape as the passage hole 36b (see FIG. 6). The rib 38a rises from the peripheral edge of the passage hole 38b toward the outlet 14 and has a predetermined height. The predetermined height applied to the ribs 36a and 38a is appropriately determined by experiments or the like.

  In this example, the measuring tube 40 is attached so as to be sandwiched between the lower center portion of the flow channel member 22 and the convex portion 42a of the bottom panel member 42 so as to be disposed in the gas flow channel. The measuring tube 40 is formed in a cylindrical shape in which the gas passage cross section is substantially rectangular, and a rectifying plate group 44 is provided in the tube. The rectifying plate group 44 is a member that rectifies the gas flowing in the measuring tube 40, and includes a plurality of rectifying plates arranged in parallel and in multiple layers. The bottom panel member 42 is provided on the bottom surface side of the gas meter 10, and has a large convex portion 42a at the center as shown in FIGS.

The ultrasonic propagation means 32 (ultrasonic transmission / reception sensor) will be briefly described. As shown in FIG. 6, the ultrasonic wave propagator 32a and the ultrasonic wave propagator 32b are arranged to face each other at predetermined positions on the upstream side and the downstream side in the gas meter 10, and have a predetermined amount with respect to the gas flow direction. Provided at an angle “θ”. An ultrasonic wave is output from one of the ultrasonic wave propagators, the ultrasonic wave is received by the other ultrasonic wave propagator, and the propagation time is measured. Both the propagation from the upstream side to the downstream side and the propagation from the downstream side to the upstream side are performed to obtain the flow velocity and flow rate of the gas. Here, when the sound velocity is “C”, the distance between the ultrasonic wave propagators 32a and 32b is “L”, and the ultrasonic wave propagation time is “T1” and “T2”, the gas flow velocity “U” is as follows. It is calculated by the formula. Further, when the cross-sectional area and the flow coefficient of the measuring tube 40 are integrated with the calculated flow velocity “U”, the gas flow rate is obtained. The flow coefficient is a coefficient for correcting the flow rate of the fluid.
U = (L / 2 cos θ) × {(1 / T1) − (1 / T2)}

  Since the gas meter 10 configured as described above includes the rectifying plates 36 and 38, the gas flows as indicated by arrows D2 and D4 shown in FIG. That is, as represented by the arrow D2, the fluid flows from the flow path member 22 through the passage hole 36b to the inlet of the measurement tube 40. Therefore, since the flow of hitting the measuring tube 40 is suppressed, the gas flow can be adjusted to some extent. Further, as indicated by the arrow D4, the gas flowing out from the outlet of the measuring tube 40 does not diffuse but goes directly to the flow path member 22 through the passage hole 38b. Therefore, since the flow of diffusing from the outlet is suppressed, the gas flow can be adjusted to some extent. By such rectification, the gas rectified by the rectifying plate group 44 becomes more laminar than when the rectifying plates 36 and 38 are not provided. Accordingly, since the turbulent gas is reduced, the ultrasonic propagation time by the ultrasonic wave propagation means 32 can be measured more accurately, and the accuracy of the gas flow velocity and flow rate is improved.

  The rectifying plates 36 and 38 described above are configured to include the ribs 36a and 38a (see FIG. 4), but may be configured not to include the ribs 36a and 38a (see FIG. 8). FIG. 7 is a graph showing a relationship in which the horizontal axis is the gas flow rate and the vertical axis is the flow coefficient for each configuration. In FIG. 7, the change of the rectifying plates 36 and 38 with the ribs 36a and 38a is represented by a square point “■”, and the change of the rectifying plates 36 and 38 without the ribs 36a and 38a is represented by a rhombus point “♦”. For this reason, the change when the current plate is not provided is represented by a triangle point “▲”. As is apparent from FIG. 7, the flow coefficient with the ribs is generally more constant than that with the ribs. In addition, when the rectifying plate is not provided, the flow coefficient tends to decrease as the flow rate increases. However, when the rectifying plates 36 and 38 are provided, the flow rate tends to be stable regardless of the increase or decrease of the flow rate. From these facts, it is shown that the ratio of turbulent flow is kept low even when the gas flow rate is changed, and the Reynolds number is lowered.

According to the embodiment described above, the following effects can be obtained.
(1) The rectifying plate 36 is arranged in the vicinity of the inlet of the measurement tube 40 so as to block the gas flow path formed by the flow path member 22 (see FIGS. 4 to 6). Since the passage hole 36b is provided at a predetermined position of the rectifying plate 36, the gas flowing in the flow path member 22 is guided and rectified. This rectification facilitates the flow of gas from the passage hole 36b toward the inlet of the measuring tube 40. In other words, hitting the measurement tube 40 when flowing from the flow path member 22 into the measurement tube 40 is suppressed. In this way, the flow of gas flowing from the flow path member 22 into the measuring tube 40 can be adjusted to some extent, and as a result, the flow rate measurement accuracy can be improved as compared with the conventional case.

(2) The rectifying plate 38 is arranged not only in the vicinity of the inlet of the measuring tube 40 but also in the vicinity of the outlet of the measuring tube 40 so as to block the gas channel formed by the channel member 22. (See FIGS. 4 and 6). With this arrangement, the gas flow can be adjusted to some extent on the outflow side, and as a result, the flow rate measurement accuracy can be further enhanced.

(3) The ribs 36a, 38a raised from the peripheral edges of the passage holes 36b, 38b are provided on the rectifying plates 36, 38 (see FIGS. 3 to 5). Since the ribs 36a and 38a have a predetermined height, the flow of gas flowing from the flow path member 22 into the measuring tube 40 can be adjusted to some extent. Therefore, as a result, the measurement accuracy of the flow rate can be improved as compared with the conventional case.

[Other Embodiments]
Although the best mode for carrying out the present invention has been described above, the present invention is not limited to this mode. In other words, various forms can be implemented without departing from the scope of the present invention. For example, the following forms may be realized.

(1) In the above-described embodiment, the flow path member 22 and the rectifying plates 36 and 38 are formed separately, and the rectifying plates 36 and 38 are attached to the flow path member 22 (see FIG. 3). ). Instead of this form, the flow path member 22 and the rectifying plates 36 and 38 may be integrally formed. According to this configuration, since the process of attaching the rectifying plates 36 and 38 is not required, the manufacturing time of the gas meter 10 can be shortened. Other than that, the difference is only whether it is a separate body or an integrated body, so that the same operational effects as those of the above-described embodiment can be obtained.

(2) In the embodiment described above, the passage holes 36b, 38b of the rectifying plates 36, 38 are formed in a rectangular shape (see FIG. 6). Instead of this form, the passage holes 36b, 38b may be formed in other shapes. Other shapes include a quadrangle and a circle (including an ellipse), but it is desirable to match the shape of the inlet and outlet of the measurement tube 40. Regardless of the shape, the gas flow can be adjusted to some extent.

(3) In the above-described embodiment, the inflow port 12 and the outflow port 14 are arranged on the upper surface to form a substantially U-shaped flow path (see FIG. 1). Instead of this form, the inflow port 12 and the outflow port 14 are arranged on the bottom surface to form an inverted U-shaped flow path, or the inflow port 12 and the outflow port 14 are arranged on the side surface so ) A character-shaped channel may be formed. In any configuration, since the inflow port 12 and the outflow port 14 are arranged on either side of the gas meter 10, the same effects as those of the above-described embodiment can be obtained. Even when the inflow port 12 and the outflow port 14 are respectively arranged on different surfaces, the operation by the rectifying plates 36 and 38 is not changed, so that the same effect as the above-described embodiment can be obtained.

(4) In the above-described embodiment, the rectifying plate 36 includes the rib 36a and the passage hole 36b, and the rectifying plate 38 includes the rib 38a and the passage hole 38b (see FIGS. 3 to 5). Instead of either one or both of the current plates, a structure may be provided that includes current regulating members 50 and 52 as shown in FIG. The rectifying member 50 includes a rib 50a and a guide passage 50b, and the rectifying member 52 includes a rib 52a and a guide passage 52b. The rectifying member 50 is provided at substantially the same position as the rectifying plate 36, and the rectifying member 52 is provided at substantially the same position as the rectifying plate 38. The difference from the rectifying plates 36 and 38 is that the guide passage 50b is connected to the inlet of the measuring tube 40, and the guide passage 52b is connected from the outlet of the measuring tube 40. Since the guide passages 50b and 52b are further prevented from hitting the measurement tube 40, the flow rate measurement accuracy can be further increased.

(5) Similarly to (4), instead of either one or both of the rectifying plates 36, 38, rectifying members 54, 56 as shown in FIG. 10 may be provided. The flow regulating member 54 connects between the flow path member 22 (inner wall surface) on the inlet 12 side and the inlet of the measurement tube 40. The rectifying member 56 connects between the outlet of the measuring tube 40 and the flow path member 22 (inner wall surface) on the outlet 14 side. Rather than simply connecting, it is desirable to form it so that it is connected in a curved manner. Since the contact with the measuring tube 40 is completely suppressed, the flow rate measurement accuracy can be further increased.

It is a front view showing the example of appearance of a gas meter. It is a top view showing the external appearance example of a gas meter. It is a disassembled perspective view explaining the structural example of a gas meter. It is sectional drawing of the IV-IV line arrow of FIG. It is sectional drawing of the VV arrow of FIG. It is sectional drawing of the VI-VI line arrow of FIG. It is a graph explaining the relationship between a flow volume and a flow coefficient. It is sectional drawing showing the example comprised using the baffle plate without a rib. It is sectional drawing showing the example comprised using the baffle plate of another shape. It is sectional drawing showing the example comprised using the baffle plate of another shape.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Gas meter 12 Inlet 14 Outlet 16 Front panel member 18 Return button 20 Display means 22 Flow path member 24 Back panel member 26 Control board 28 Power supply pack 30 Pressure sensor 32 Ultrasonic propagation means 32a, 32b Ultrasonic wave propagation device 34 Shut-off valve 36, 38 Current plate 36a, 38a Rib (head)
36b, 38b Passage hole 40 Measuring tube 42 Bottom panel member 42a Convex portion 44 Rectifying plate group 50, 52, 54, 56 Rectifying member 50a, 52a Rib (head)
50b, 52b Guide passage K space

Claims (3)

A channel member formed in a substantially U-shaped cylindrical shape as a gas channel from the inlet to the outlet;
A measuring tube disposed in the gas flow path formed by the flow path member and formed so that the gas passage cross section is substantially rectangular;
Ultrasonic wave propagation means for propagating the ultrasonic wave between two predetermined points provided on the upstream side and the downstream side in the measurement tube and outputting a detection signal;
A gas meter comprising flow rate calculation means for calculating a flow rate of the gas flowing in the measurement tube based on a detection signal output from the ultrasonic wave propagation means,
A rectifying plate that is arranged in the vicinity of the inflow port of the measurement tube so as to block the gas flow path formed by the flow path member, and rectifies the gas flowing in the flow path member through a passage hole provided at a predetermined position. Having a gas meter. A gas meter according to claim 1, wherein
The rectifying plate is arranged in the vicinity of the inflow port of the measurement tube and in the vicinity of the outflow port of the measurement tube so as to close the gas flow path formed by the flow path member. A gas meter according to claim 1 or 2, wherein
A gas meter having a structure in which the current plate is provided with a rib that stands up from the periphery of the passage hole and has a predetermined height.

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