Flow meter

Abstract

To provide a flow meter capable of suppressing a decrease in measurement accuracy of a fluid to be measured.SOLUTION: A flow meter 100 includes an adjuster 40 attached to at least one of the measurement fluid inlet 24 and the measurement fluid outlet 25 of the measurement unit 20 . The adjuster 40 has a tubular portion 41 and a pair of introduction plates 42A, 42B that extend in the extension direction within an adjustment flow path 43 of the tubular portion 41 and introduce a fluid to be measured in the adjustment flow path 43 to a measurement flow path 26. The pair of introduction plates 42A, 42B extend at a predetermined angle such that the inner width dimension between the pair of introduction plates 42A, 42B changes monotonically toward the measurement flow path 26.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a flowmeter that measures the flow rate of a fluid to be measured. [Background technology]

[0002] Patent Document 1 describes a flowmeter that includes a main body case having a main body inlet and a main body outlet, and a measurement unit that is disposed inside the main body case and measures the flow rate of a fluid to be measured. In the flowmeter, the measurement unit measures the flow rate of the fluid to be measured that flows in from the main body inlet of the main body case over a predetermined period of time. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2015-224872 A Summary of the Invention [Problem to be solved by the invention]

[0004] In a flow meter, when pulsation occurs in the flow of a fluid to be measured, a difference may occur between the flow rate distribution in the forward direction along the flow of the fluid to be measured and the flow rate distribution in the reverse direction against the flow of the fluid to be measured. In such a case, an error may occur between the measurement value in the forward direction of the fluid to be measured and the measurement value in the reverse direction, which may make it impossible to accurately measure the integrated value of the flow rate of the fluid to be measured over a given period of time.

[0005] The present invention has been made in consideration of the above-mentioned problems, and has an object to provide a flow meter capable of suppressing a decrease in the measurement accuracy of a fluid to be measured. [Means for solving the problem]

[0006] In order to solve the above problems, the flowmeter disclosed in this embodiment includes a main body case having a main body inlet, a main body outlet, and a chamber communicating with the main body inlet and the main body outlet, and a measurement unit disposed in the chamber of the main body case and measuring the flow rate of the measured fluid in the chamber at a predetermined time. The measurement unit includes a measurement flow path extending in a predetermined direction, a measurement inlet located on one side of the measurement flow path extension direction, and a measurement outlet located on the other side of the measurement flow path extension direction, and a sensor measuring a value corresponding to the flow rate of the measured fluid flowing through the measurement flow path, and includes an adjuster attached to at least one of the measurement inlet and the measurement outlet in the measurement device case, and the adjuster includes a tubular portion having an adjustment flow path extending in the same direction as the measurement flow path extension direction by being attached to at least one of the measurement inlet and the measurement outlet, and a pair of introduction plates extending in the adjustment flow path in the extension direction of the measurement flow path and guiding the measured fluid in the adjustment flow path to the measurement flow path. The pair of introduction plates extend at a predetermined angle so that the inner width dimension between the pair of introduction plates in a direction horizontally intersecting the extension direction of the measurement flow path changes monotonically toward the measurement flow path.

[0007] In the above configuration, at the port on the side where the measuring device of the measuring unit is attached, the flow rate distribution of the measured fluid that has flowed into the adjustment flow path of the regulator is adjusted by the pair of introduction plates and then flows into the measurement flow path. As a result, even if there is variation in the flow rate distribution of the measured fluid between the forward and reverse directions in the chamber, the variation in the flow rate distribution is adjusted by the regulator, so that the error in the measurement value of the measured fluid in the forward direction or the measurement value in the reverse direction is reduced, and it is possible to suppress a decrease in the measurement accuracy of the flow rate of the measured fluid at a given time.

[0008] The measurement unit has a plurality of partial flow paths formed within the measurement flow path, arranged in a direction that intersects horizontally with the extension direction of the measurement flow path, and the sensor measures a value corresponding to the flow rate of the fluid to be measured, with the partial flow paths among the plurality of partial flow paths excluding the partial flow paths located on the outer side in the direction that intersects horizontally with the extension direction of the measurement flow path as its measurement range, and the pair of introduction plates extend at a predetermined angle so that the inner width dimension between the pair of introduction plates in the direction that intersects horizontally with the extension direction of the adjustment flow path monotonically decreases toward the measurement flow path. In the above configuration, the pair of introduction plates of the regulator makes it easier for the fluid to be measured to be introduced into the partial flow path which is the measurement range, and the flow rate of the fluid to be measured flowing through this measurement range can be made uniform.

[0009] The main body case has chambers, an inlet side chamber that communicates with the main body inlet, and an outlet side chamber that communicates with the main body outlet, and the measurement unit forms a flow path between the main body inlet and main body outlet by connecting the measurement flow path to the inlet side chamber on the measurement inlet side and connecting the measurement flow path to the outlet side chamber on the measurement outlet side. When the measurement flow path of the measurement unit is connected to separate chambers on the measurement inlet side and the measurement outlet side, differences in the volume and shape of each chamber tend to cause differences in the flow rate distribution of the measured fluid between the forward and reverse directions. In the above configuration, even in a flowmeter having such a configuration, the measured fluid can be made to flow into the measurement flow path while the regulator adjusts the variation in flow rate distribution between the forward and reverse directions, and thus the measurement accuracy of the measured fluid can be suppressed from decreasing.

[0010] The measuring unit is disposed within the main body case and is provided with an outlet-side chamber forming section which forms an outlet-side chamber, and the end of the measuring unit on the measurement inlet side is inserted into the opening of the outlet-side chamber forming section, thereby connecting the measuring flow path to the outlet-side chamber, and the regulator is attached to the measuring outlet of the measuring unit and is positioned within the outlet-side chamber, and the outlet-side chamber forming section has a pressure-reducing slope which is an inclined curved surface on the inner surface facing the measuring outlet of the measuring unit. The regulator is attached to the measurement outlet of the measurement unit, thereby generating a pressure loss in the flow of the measured fluid flowing between the outflow chamber and the measurement flow path. In the above configuration, the inner surface of the outflow chamber forming part facing the measurement outlet to which the regulator is attached has a pressure reducing slope, so that the pressure loss of the measured fluid generated by the regulator can be reduced by the amount of pressure loss reduction caused by the pressure reducing slope, and thus the increase in the pressure loss of the measured fluid in the entire flow meter can be suppressed.

[0011] The pair of introduction plates include a pair of first introduction plates and a pair of second introduction plates located within the adjustment flow path outside the first introduction plates in a direction horizontally intersecting the extension direction of the adjustment flow path, and the second introduction plates have an extension length in the extension direction of the adjustment flow path that is shorter than that of the first introduction plates. In the above configuration, by making the extension length of the second introduction plate shorter than the extension length of the first introduction plate, it is possible to suppress an increase in loss due to the first and second introduction plates while suppressing variations in flow rate distribution. [Brief description of the drawings]

[0012] [Figure 1] FIG. [Diagram 2] FIG. 2 is a diagram showing the inside of a flow meter. [Diagram 3] FIG. 2 is a plan view showing the inside of the flow meter. [Figure 4] FIG. 4 is a cross-sectional view of the measurement unit. [Diagram 5] FIG. 4 is a diagram illustrating a measurement flow path in the measurement unit. [Figure 6] FIG. [Figure 7] FIG. [Figure 8] FIG. 4 is a diagram illustrating the flow rate distribution of city gas flowing in the forward direction. [Figure 9] FIG. 13 is a diagram illustrating the flow rate distribution of city gas flowing in the reverse direction in a comparative example. [Figure 10] FIG. 4 is a diagram illustrating the flow rate distribution of city gas flowing in the reverse direction according to the embodiment. [Figure 11]FIG. 11 is a cross-sectional view of a regulator according to a modified example. [Figure 12] FIG. 11 is a cross-sectional view of a regulator according to a modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] (First embodiment) Hereinafter, a flowmeter according to the present embodiment will be described with reference to the drawings. The flowmeter is a city gas meter that measures the flow rate of city gas, which is an example of a fluid to be measured. The flowmeter is used by being connected to a pipe (not shown) through which city gas flows.

[0014] FIG. 1 is an external view of the flowmeter 100. FIG. 2 is a view showing the inside of the flowmeter 100. FIG. 3 is a plan view showing the inside of the flowmeter 100. Hereinafter, when the flowmeter 100 is in use, the up-down direction is referred to as the up-down direction D1, and the direction along the width of the flowmeter 100 (the direction in which a main body inlet 93 and a main body outlet 94, which will be described later, are aligned) is referred to as the width direction D2. Additionally, the direction along the depth of the flowmeter 100 is referred to as the depth direction D3. The width direction D2 and the depth direction D3 are also directions that intersect with each other in the horizontal direction.

[0015] 1 to 3, the flowmeter 100 mainly includes an upper case 90, a lower case 80, an exhaust pipe 70, an internal unit case 75, a measurement unit 20, and a regulator 40. In this embodiment, the upper case 90 and the lower case 80 are an example of a main body case.

[0016] The upper case 90 is a container that opens downward when in use. Specifically, the upper case 90 has a ceiling portion 91 that is substantially rectangular in plan view, and side walls 92 that extend downward from four sides of the ceiling portion 91. The ceiling portion 91 is formed with a main body inlet 93 and a main body outlet 94, which are openings facing upward. In the ceiling portion 91, the main body inlet 93 and the main body outlet 94 are formed side by side at a predetermined distance apart in the width direction D2. The side walls 92 are walls that surround the opening in the upper case 90, and a flange portion 95 that protrudes outward is formed on the downward side.

[0017] An inlet side cap 14 for connecting the upper case 90 to piping is attached to a main body inlet 93 of the upper case 90. An outlet side cap 15 for connecting the upper case 90 to piping is attached to a main body outlet 94 of the upper case 90.

[0018] The lower case 80 is a shielding member that shields the opening of the upper case 90. The lower case 80 has a flange portion 81, which is screwed to a flange portion 95 of the upper case 90. By screwing the lower case 80 to the upper case 90, the lower case 80 is fixed in a state where its upper surface faces the ceiling portion 91 of the upper case 90. By screwing the lower case 80 to the upper case 90, the inside of the upper case 90 is made airtight, and an inlet side chamber 16 through which the city gas convects is formed.

[0019] The exhaust pipe 70 and the inner unit case 75 are members that form the outflow side chamber 17, which is a part of the chamber. The exhaust pipe 70 is a member that opens downward when in use. The exhaust pipe 70 has an exhaust port 71 at the top and a flange portion 72 at the bottom that protrudes outward from the edge of the opening. The exhaust port 71 is inserted into a main body outlet 94, and is connected to piping via an outlet side nozzle 15 attached to the main body outlet 94.

[0020] The inner unit case 75 is a member that opens upward in a usage state and has a flange portion 76 on the opening edge. The side of the inner unit case 75 has a unit mounting opening 77, which is an opening into which the outflow end of the measurement unit 20 (a measurement outlet 25 described later) can be inserted. The inner unit case 75 has a pressure reducing slope 78 inside, which is an inclined curved surface facing the unit mounting opening 77. The pressure reducing slope 78 is a curved surface whose surface facing the unit mounting opening 77 is inclined at a predetermined curvature. Specifically, the pressure reducing slope 78 is a curved surface that inclines downward in the up-down direction D1 from the inner surface 75a on the side where the unit mounting opening 77 is not formed in the width direction D2 toward the inner surface 75b on the side where the unit mounting opening 77 is formed in the width direction D2 in a usage state.

[0021] The exhaust pipe 70 and the inner unit case 75 are screwed together at the flanges 72, 76 with their openings facing each other, thereby forming an outlet chamber 17 through which the city gas flowing out from the measurement unit 20 flows. This outlet chamber 17 is a space that is connected to the inlet chamber 16 via the measurement unit 20 and is connected to piping via the main body outlet 94 of the upper case 90. In this embodiment, the exhaust pipe 70 and the inner unit case 75 are an example of an outlet chamber forming portion.

[0022] Inside the inflow chamber 16, a measurement unit 20 is attached to a unit mounting opening 77 of the inner unit case 75 via a packing 18 which is an elastic member. The measurement unit 20 is a device which measures the flow rate (liters / hour) of the city gas which has flowed into the inflow chamber 16 or the outflow chamber 17. As shown in FIG. 4, the measurement unit 20 mainly includes a measurement device case 21, ultrasonic vibrators 27A and 27B which are sensors, and a partition plate 29.

[0023] The measuring instrument case 21 has a measuring flow passage forming section 22 and a sensor accommodating section 23. The measuring flow passage forming section 22 has a measuring inlet 24, which is a rectangular opening, and a measuring outlet 25, and is a square tube-shaped section. In the measuring flow passage forming section 22, a measuring flow passage 26 through which city gas flows is formed between the measuring inlet 24 and the measuring outlet 25. The measuring flow passage 26 is a flow passage that extends linearly while maintaining a substantially rectangular opening shape. Hereinafter, the extending direction of the measuring flow passage 26 is also referred to as the extending direction DA. In this embodiment, the measuring unit 20 is attached to the inner machine case 75 with the extending direction DA of the measuring flow passage 26 directed substantially parallel to the width direction D2 of the flowmeter 100, so that the extending direction DA is also a direction along the width direction D2.

[0024] A partition plate 29 that divides the measurement flow path 26 into a plurality of partial flow paths 30 is disposed inside the measurement flow path forming portion 22. Specifically, the plurality of partition plates 29 are disposed in the measurement flow path 26 with their surfaces facing each other in a cross direction DB that crosses the extension direction DA on a horizontal plane, thereby dividing the measurement flow path 26 into a plurality of partial flow paths 30 that are arranged in the cross direction DB.

[0025] In this embodiment, eight partial flow paths 30A, 30B, 30C, 30D, 30E, 30F, 30G, and 30H are formed in the measurement flow path 26. In the following, when each partial flow path 30 partitioned by the partition plate 29 is to be distinguished, the alphabets "A, B, C, D, E, F, G, and H" are added to the reference numerals. The inner width of each partial flow path 30 in the cross direction DB is the same, but this is not limited thereto. For example, the inner width of the partial flow path 30D and 30E located at the center in the cross direction DB may be larger than the inner width of the other partial flow paths 30A to 30C and 30F to 30H. The number of partial flow paths 30 is not limited to eight, and may be a number equal to or greater than eight and less than eight, or a number greater than eight.

[0026] Ultrasonic transducers 27A and 27B, which are sensors, are disposed in sensor housing 23. By disposing ultrasonic transducers 27A and 27B above measurement flow path 26, a V-shaped ultrasonic propagation path is formed in which ultrasonic waves from one ultrasonic transducer 27A and 27B are reflected by the bottom surface of measurement flow path 26 and transmitted to the other ultrasonic transducer 27A and 27A. This makes it possible to measure the flow rate of city gas flowing through measurement flow path 26 according to the ultrasonic wave reception period.

[0027] Ultrasonic transducers 27A and 27B measure the flow velocity of the city gas by using as a measurement range some of partial flow paths 30A to 30H formed in measurement flow path 26. Specifically, measurement unit 20 uses only partial flow paths 30D and 30E as a measurement range among partial flow paths 30A to 30H, and does not use partial flow paths 30A, 30B, 30C, 30F, 30G, and 30H as a measurement range.

[0028] Moreover, in the sensor housing 23, a measurement circuit 28 to which the ultrasonic transducers 27A, 27B are electrically connected is disposed above each ultrasonic transducer 27A, 27B. In this embodiment, the measurement circuit 28 can calculate the flow rate of the city gas per unit time by multiplying the flow velocity measured by the measurement unit 20 by the cross-sectional area of ​​the measurement flow path 26. Then, the measurement circuit 28 can calculate the integrated flow rate of the city gas for a predetermined time as a measurement value by adding up the flow rates per unit time for the measurement time.

[0029] In this embodiment, the integrated flow rate, which is a measurement value measured by measurement circuit 28, may include a forward flow rate and a reverse flow rate measured by ultrasonic transducers 27A, 27B. Here, the forward flow rate is the flow rate of city gas flowing from measurement inlet 24 to measurement outlet 25 in measurement flow path 26, and is measured as a positive value. The reverse flow rate is the flow rate of city gas flowing from measurement outlet 25 to measurement inlet 24 in measurement flow path 26, and is measured as a negative value.

[0030] The regulator 40 is attached to the measurement outlet 25 of the measurement unit 20. As shown in FIG. 6 and FIG. 7, the regulator 40 mainly includes a tubular portion 41 and a pair of introduction plates 42A, 42B provided inside the tubular portion 41. The tubular portion 41 is a square tube-shaped member having a rectangular opening. Hereinafter, one opening of the tubular portion 41 into which the measurement outlet 25 of the measurement unit 20 is inserted is referred to as a first opening 44, and the opening on the opposite side to the first opening 44 is described as a second opening 45. In this embodiment, the inner dimension of the first opening 44 is a dimension that allows the measurement outlet 25 of the measurement unit 20 to be inserted, and is larger than the inner dimension of the second opening 45.

[0031] An adjustment flow passage 43 is formed between the first and second openings 44, 45. The adjustment flow passage 43 is a flow passage extending in a substantially rectangular shape between the first and second openings 44, 45. The adjustment flow passage 43 is provided with a pair of introduction plates 42A, 42B that extend in the same direction as the extension direction DA in the usage state and introduce the city gas flowing through the adjustment flow passage 43 to the measurement flow passage 26. In the usage state of the regulator 40, the pair of introduction plates 42A, 42B are arranged in the intersecting direction DB with their faces facing each other in the adjustment flow passage 43 (FIG. 7).

[0032] When a virtual line L extending along the extension direction DA is used as a reference, the pair of introduction plates 42A, 42B are inclined at a predetermined angle in the cross direction DB so as to approach this virtual line L from the outside toward the measurement unit 20. As a result, the inner width dimension W of the pair of introduction plates 42A, 42B in the cross direction DB changes monotonically (monotonically decreases in this figure) from the second opening 45 toward the first opening 44, that is, toward the measurement flow path 26.

[0033] The end of the measurement outlet 25 of the measurement unit 20 is inserted into the unit mounting opening 77 of the inner machine case 75, so that the measurement flow path 26 and the outlet side chamber 17 communicate with each other on the measurement outlet 25 side. The measurement inlet 24 side of the measurement unit 20 is located within the inlet side chamber 16, and the measurement flow path 26 and the inlet side chamber 16 communicate with each other on the measurement inlet 24 side. As a result, the measurement unit 20 forms a part of the flow path connecting the inlet side chamber 16 and the outlet side chamber 17 between the main body inlet 93 and the main body outlet 94.

[0034] In the flowmeter 100 configured as described above, city gas flowing in through the main body inlet 93 of the upper case 90 flows into the inlet chamber 16. Inside the inlet chamber 16, the city gas flows into the measurement flow path 26 from the measurement inlet 24 of the measurement unit 20. As already described, the measurement circuit 28 of the measurement unit 20 uses the ultrasonic transducers 27A, 27B to measure the flow rate per unit time of the city gas flowing through the partial flow paths 30D, 30E, which are the measurement range, and measures the integrated flow rate for a predetermined time by integrating the measured flow rate for a predetermined time.

[0035] The city gas flowing out from the measurement outlet 25 of the measurement unit 20 flows into the outlet chamber 17. The city gas flowing into the outlet chamber 17 is discharged to the piping via the main body outlet 94 of the upper case 90. As described above, the pressure relieving slope 78 is formed in the inner unit case 75 that forms the outlet chamber 17. As a result, the pressure relieving slope 78 can suppress an increase in loss due to the regulator 40 attached to the measurement unit 20.

[0036] Although not shown, the flowmeter 100 includes a control board equipped with a microcomputer or the like, and this control board is electrically connected to the measurement circuit 28 and the shutoff valve of the measurement unit 20. The control board detects an abnormality in the supply gas flow rate, etc., based on the integrated flow rate of the city gas output from the measurement unit 20 over a predetermined period of time, and drives the shutoff valve to stop the supply of city gas if an abnormality in a predetermined gas shutoff target is detected. The control board is also configured to be able to output the measurement value of the city gas output from the measurement unit 20 to a personal computer or the like (not shown).

[0037] On the other hand, when the city gas flows in the opposite direction due to pulsation, the city gas flows into the outflow chamber 17 from the main outlet 94 of the upper case 90. The city gas that flows into the outflow chamber 17 passes through the regulator 40 located inside the outflow chamber 17, and flows into the measurement flow path 26 of the measurement unit 20. The city gas that flows into the measurement flow path 26 passes through each of the partial flow paths 30A-30H separated by the partition plate 29. Even in this case, in the measurement unit 20, the ultrasonic transducers 27A and 27B measure the flow rate per unit time of the city gas flowing through the partial flow paths 30D and 30E, which are the measurement ranges, and measure the integrated flow rate for the specified time by integrating the measured flow rate for the specified time.

[0038] In the flowmeter 100, a difference occurs between the flow distribution on the forward flow side of the city gas and the flow distribution on the reverse flow side due to the difference in shape between the inlet chamber 16 on the upstream side of the measurement unit 20 and the outlet chamber 17 on the downstream side. In particular, in a configuration in which the measurement unit 20 measures the flow rate in the partial flow paths 30D and 30E, which are part of the measurement flow path 26, as the measurement range, there is a concern that the uneven structure before and after the measurement unit 20 will cause a difference in the flow distribution to the measurement range in the measurement flow path 26, resulting in a significant decrease in measurement accuracy.

[0039] Fig. 8 is a diagram explaining the flow of city gas in the forward direction. Fig. 9 is a diagram explaining, as a comparative example, the flow of city gas in the reverse direction when regulator 40 is not attached to measurement unit 20. Fig. 10 is a diagram explaining the flow of city gas in the reverse direction when regulator 40 is attached to measurement unit 20. In Figs. 8 to 10, arrows indicate the flow distribution of city gas. In the flow distribution, the direction of the arrow indicates the flow direction of city gas, and the length of the arrow indicates the flow rate of city gas per unit time.

[0040] 8, when the city gas flows in the forward direction, the volume of the inlet chamber 16 is large, and the flow rate distribution Q1 of the city gas flowing in the forward direction has a small difference in flow rate in the cross direction DB in which the partial flow paths 30A to 30H are arranged. Therefore, in a configuration in which the measurement unit 20 uses the partial flow paths 30D and 30E as the measurement range, the measurement accuracy of the flow rate in the forward direction does not decrease significantly.

[0041] On the other hand, as shown in FIG. 9, when the city gas flows in the reverse direction, the outflow chamber 17 has a smaller volume than the inflow chamber 16, and the shape is different. Therefore, in the city gas flowing in the reverse direction, the flow rate distribution Q2 has a large difference in flow rate in the cross direction DB in which the partial flow paths 30A to 30H are arranged. When the regulator 40 is not attached to the measurement unit 20, the measurement accuracy of the flow rate in the reverse direction is significantly reduced in the configuration in which the measurement unit 20 uses the partial flow paths 30D and 30E as the measurement range. Therefore, when pulsation occurs in which the city gas flows in the forward and reverse directions, the measurement accuracy of the measurement value, which is the integrated flow rate, may be significantly reduced due to the reduction in the measurement accuracy of the flow rate in the reverse direction.

[0042] In this embodiment, as shown in Fig. 10, a regulator 40 is attached to the measurement outlet 25 side of the measurement unit 20. Therefore, the flow distribution Q3 of the city gas flowing in the reverse direction becomes an adjusted flow distribution Q4 by passing through the regulator 40. As a result, the difference in the flow rate flowing through each partial flow path 30A-30H becomes small, and even when the partial flow paths 30D and 30E are used as the measurement range, the decrease in the measurement accuracy of the flow rate in the reverse direction is not significant. Therefore, even when pulsation occurs in which the city gas flows in the forward and reverse directions, the decrease in the measurement accuracy of the flow rate in the reverse direction is suppressed, and the decrease in the measurement accuracy of the integrated flow rate (measurement value) in a given time is suppressed.

[0043] There is a concern that pressure loss may occur when city gas flows through the adjustment flow path 43 of the regulator 40. In this embodiment, the measurement outlet 25 to which the regulator 40 is attached faces the pressure relief slope 78 of the inner unit case 75. This reduces the pressure loss of the city gas flowing between the measurement outlet 25 to which the regulator 40 is attached and the outlet-side chamber 17 by the amount of pressure loss reduction caused by the pressure relief slope 78, and suppresses an increase in pressure loss in the entire flowmeter 100.

[0044] The present embodiment described above can provide the following advantages. The regulator 40 attached to at least one of the measurement inlet 24 and the measurement outlet 25 of the measurement unit 20 has a pair of introduction plates 42A, 42B. The pair of introduction plates 42A, 42B extend at a predetermined angle so that the inner width dimension in the cross direction DB between the pair of introduction plates 42A, 42B changes monotonically as it approaches the measurement flow path 26. As a result, even if there is variation in the flow rate distribution between the forward and reverse directions in the city gas, the regulator 40 attached to the port with the variation in flow rate distribution can adjust the variation in the flow rate distribution to allow the city gas to flow into the measurement range of the measurement flow path 26. As a result, it is possible to suppress a decrease in the measurement accuracy of the integrated flow rate, which is a measurement value.

[0045] In the measurement unit 20, a plurality of partial flow paths 30A-30H arranged in the intersecting direction DB are formed in the measurement flow path 26, and the ultrasonic transducers 27A, 27B measure the flow rate of city gas in the partial flow paths 30D, 30E, which are the measurement range. The pair of introduction plates 42A, 42B extend in the adjustment flow path 43 at an incline such that the inner width dimension in the intersecting direction DB monotonically decreases toward the measurement flow path 26. As a result, the pair of introduction plates 42A, 42B make it easier for the city gas to be introduced into the partial flow paths 30D, 30E, which are the measurement range, and the flow rate of the city gas flowing through this measurement range can be made uniform.

[0046] In a configuration in which the measurement inlet 24 and the measurement outlet 25 of the measurement unit 20 are connected to separate chambers, differences in flow rate distribution of city gas between the forward and reverse directions are likely to occur due to differences in the volumes and shapes of the chambers 16, 17. Even in a flowmeter 100 having such a configuration, city gas can be made to flow into the measurement flow path 26 while the regulator 40 adjusts the variation in flow rate distribution between the forward and reverse directions, and thus the deterioration of the measurement accuracy of the integrated flow rate of city gas can be suppressed.

[0047] By providing a pressure reducing slope 78, which is an inclined curved surface, on the inner surface of the inner unit case 75 facing the measurement outlet 25 to which the regulator 40 is attached, an increase in pressure loss throughout the flow meter 100 can be suppressed.

[0048] (Modification of the first embodiment) The adjuster 40 may have a configuration shown in Fig. 11. Fig. 11 is a cross-sectional view illustrating an adjuster 40 according to a modified example. The adjuster 40 has a pair of second introduction plates 46A, 46B as a pair of introduction plates in addition to the pair of first introduction plates 42A, 42B described in the first embodiment. The pair of second introduction plates 46A, 46B are located outside the first introduction plates 42A, 42B in the cross direction DB in the adjustment flow path 43. The second introduction plates 46A, 46B are plates whose extension length in the extension direction DA is shorter than that of the first introduction plates 42A, 42B.

[0049] In the above configuration, the regulator 40 has the second introduction plates 46A, 46B in addition to the first introduction plates 42A, 42B, making it easier to introduce city gas into the measurement range with the two sets of introduction plates 42, 46. Also, by making the extension length of the second introduction plates 46A, 46B shorter than the extension length of the first introduction plates 42A, 42B, it is possible to suppress the increase in pressure loss of city gas due to the two introduction plates 42, 46 while suppressing the variation in flow rate.

[0050] The regulator 40 may have a pair of introduction plates 47A, 47B shown in Fig. 12. When the pair of introduction plates 47A, 47B shown in Fig. 12 is based on a virtual line L extending along the extension direction DA, the pair of introduction plates 47A, 47B are inclined at a predetermined angle from the virtual line L in the cross direction DB toward the measurement unit 20 so as to move outward from the virtual line L. That is, in the use state of the regulator 40, the inner width dimension in the cross direction DB between the pair of introduction plates 47A, 47B is inclined so as to monotonically increase toward the measurement flow path 26. As a result, when the flow distribution of the city gas increases from the center (i.e., the position of the virtual line L) toward the outside in the cross direction DB, the pair of introduction plates 47A, 47B makes it difficult for the city gas to flow into the measurement range (i.e., the partial flow paths 30D, 30E), so that the difference in the flow rate of the city gas can be reduced compared to other parts.

[0051] (Other embodiments) The technology disclosed in this specification is not limited to the above-described embodiments, and can be modified in various forms without departing from the spirit of the invention. For example, the following modifications are also possible. In the above embodiment, the regulator 40 is attached to the measurement outlet 25 of the measurement unit 20. Alternatively, when adjusting the flow distribution of the city gas on the forward flow side, the regulator 40 may be attached to the measurement inlet 24 of the measurement unit 20.

[0052] In the above-described embodiment, the flow meter 100 includes one measurement unit 20. Alternatively, the flow meter 100 may include two or more measurement units 20.

[0053] In the above embodiment, the flowmeter 100 uses the ultrasonic vibrators 27A and 27B as sensors. The sensor is not limited to the ultrasonic vibrator as long as it can measure the flow rate of the fluid to be measured.

[0054] In the above embodiment, the fluid to be measured is described as being city gas, but the fluid to be measured may be LP gas instead. [Explanation of symbols]

[0055] 16...inlet chamber, 17...outlet chamber, 20...measuring unit, 21...measuring instrument case, 24...measuring inlet, 25...measuring outlet, 26...measuring flow path, 27A, 27B...ultrasonic transducer, 40...regulator, 41...tubular portion, 42A, 42B...pair of introduction plates, 43...regulating flow path, 80...lower case, 90...upper case, 93...main body inlet, 94...main body outlet, 100...flow meter

Claims

1. a main body case having a main body inlet, a main body outlet, and a chamber communicating with the main body inlet and the main body outlet; and a measurement unit disposed in the chamber of the main body case and configured to measure a flow rate of a fluid to be measured in the chamber at a predetermined time, the measurement unit comprising: a measuring instrument case having a measurement flow path extending in a predetermined direction, a measurement inlet located on one side of the measurement flow path in the extension direction, and a measurement outlet located on the other side of the measurement flow path in the extension direction; a sensor that measures a value corresponding to a flow rate of the measurement target fluid flowing through the measurement flow path, a regulator attached to at least one of the measurement inlet and the measurement outlet in the measuring instrument case; The regulator is a tubular portion that is attached to at least one of the measurement inlet and the measurement outlet to communicate with the measurement flow path and has an adjustment flow path extending in the same direction as the extension direction of the measurement flow path; a pair of introduction plates extending in an extension direction of the measurement flow path within the adjustment flow path and introducing the fluid to be measured from the adjustment flow path to the measurement flow path; The pair of introduction plates are A flow meter characterized in that an inner width dimension between the pair of introduction plates in a direction horizontally intersecting the extension direction of the adjustment flow path extends at a predetermined angle so as to change monotonically toward the measurement flow path.

2. The measuring unit includes: A plurality of partial flow paths are formed in the measurement flow path and are arranged in a direction horizontally intersecting an extension direction of the measurement flow path, The sensor includes: measuring a value corresponding to a flow rate of the fluid to be measured within a measurement range including the partial flow paths, excluding the partial flow paths located on the outer side in a direction horizontally intersecting with an extension direction of the measurement flow path; The pair of introduction plates are 2. The flow meter according to claim 1, wherein an inner width dimension between the pair of introduction plates in a direction horizontally intersecting the extension direction of the adjustment flow path extends at a predetermined angle so as to monotonically decrease toward the measurement flow path.

3. The main body case includes: The chambers include an inlet side chamber communicating with the main body inlet and an outlet side chamber communicating with the main body outlet, The measuring unit includes:

3. The flow meter according to claim 1, wherein the measurement flow path is connected to the inlet side chamber on the measurement inlet side, and the measurement flow path is connected to the outlet side chamber on the measurement outlet side, thereby forming a flow path between the main body inlet and the main body outlet.

4. an outflow side chamber forming portion disposed in the main body case and forming the outflow side chamber, The measuring unit includes: an end portion of the measurement inlet port is inserted into an opening of the outlet-side chamber forming portion, thereby communicating the measurement flow path with the outlet-side chamber; the regulator is attached to the measurement outlet of the measurement unit and is located within the outlet chamber; The flowmeter according to claim 3 , wherein the outlet-side chamber forming portion has a pressure-relieving slope that is an inclined curved surface on an inner surface facing the measurement outlet of the measurement unit.

5. The pair of introduction plates are A pair of first introduction plates; a pair of second introduction plates located outside the first introduction plate in a direction horizontally intersecting the extension direction of the adjustment flow path in the adjustment flow path, The flowmeter according to claim 1 , wherein the second introduction plate has an extension length in the extension direction of the adjustment flow passage that is shorter than that of the first introduction plate.

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