Gas meter

Abstract

To provide a gas meter capable of reducing the labor and man-hours by sharing a main body case of a die-cast gas meter and making a measurement adapter housing a measurement tube according to the gas flow rate detachable to a main body part having the main body case. [Solution] It is composed of a main body 10 and a measurement adaptor 30 that is detachable from the main body. The main body has a gas inlet, a gas outlet, and a main body side mounting opening with an inlet side opening communicating with the gas inlet and an outlet side opening communicating with the gas outlet. The measurement adaptor has an adapter side mounting opening corresponding to the main body side mounting opening, a measurement inflow space communicating with the inlet side opening, a measurement outflow space communicating with the outlet side opening, a measurement unit 40 that measures the gas flow rate, and an adapter case 31 that houses the measurement unit. Multiple types of measurement units are prepared according to the gas flow rate to be measured, and each has the same external size and is interchangeable with the adapter case.

Description

[Technical field]

[0001] The present invention relates to a gas meter that measures a gas flow rate. [Background technology]

[0002] In recent years, small gas meters that house a measuring tube that uses ultrasonic waves to measure gas flow rate instead of the so-called membrane type measuring device have become popular. The housing of the main body of the gas meter is made of die-cast metal such as aluminum to ensure safety.

[0003] For example, Patent Documents 1 and 2 disclose a gas meter in which an ultrasonic measuring tube is housed in a predetermined location of an aluminum die-cast product in which the inside of the meter case (main body) is divided into a number of compartments. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2023-001452 A [Patent Document 2] JP 2022-181906 A Summary of the Invention [Problem to be solved by the invention]

[0005] Ultrasonic measuring tubes detect the flow velocity of gas flowing inside a rectangular tube with a constant cross-sectional area, and measure the gas flow rate using the cross-sectional area and gas flow rate. For this reason, if the gas flow rate is smaller than necessary, the detection error will be large, so a minimum flow rate is often set according to the size of the measuring tube. Also, if the gas flow rate is larger than necessary, pressure loss will occur, so a maximum flow rate is often set according to the size of the measuring tube. Therefore, a measuring tube of a size according to the gas flow rate to be detected is installed inside the gas meter. Particularly in factories, etc., a gas meter with a measuring tube according to the gas flow rate used in the equipment in the factory is required, so a gas meter according to the gas flow rate must be prepared and installed.

[0006] In the gas meters described in Patent Documents 1 and 2, die-cast meter cases (main bodies) must be prepared according to the size of the measuring pipe appropriate for the gas flow rate, which increases the number of types of meter cases (main bodies). At the meter case manufacturing site, the more types of meter cases there are, the more dies are required to manufacture the die-cast meter cases, which increases the amount of work and labor required, which is not desirable. Also, at the gas meter assembly site, the more types of meter cases there are, the more work and labor required for assembly and management increases, which is not desirable.

[0007] The present invention has been devised in consideration of the above points, and has an objective of providing a gas meter that can reduce the effort and labor required by using a common main body case for the die-cast gas meter and making it possible to attach and detach a measurement adapter that houses a measurement unit corresponding to the gas flow rate to the main body portion having the main body case. [Means for solving the problem]

[0008] In order to solve the above problems, a first invention is a gas meter for measuring a gas flow rate, the gas meter being composed of a main body and a measurement adaptor detachable from the main body. The main body has a gas inlet through which gas flows in, a gas outlet through which gas flows out, a main body-side mounting opening to which the measurement adaptor is attached, an inlet-side opening provided in the main body-side mounting opening and communicating with the gas inlet, and an outlet-side opening provided in the main body-side mounting opening and communicating with the gas outlet. The measurement adapter includes an adapter-side mounting opening that is attached to the main body-side mounting opening of the main body, a measurement inflow space that communicates with the inflow opening when attached to the main body, a measurement outflow space that communicates with the outflow opening when attached to the main body, a measurement unit that is disposed between the measurement inflow space and the measurement outflow space and that measures the gas flow rate that flows from the measurement inflow space to the measurement outflow space, and an adapter case that houses the measurement unit and in which the adapter-side mounting opening, the measurement inflow space, and the measurement outflow space are formed.The measurement unit is of a plurality of types according to the gas flow rate to be measured, and the plurality of types of measurement units are set to have the same external size and are replaceable with respect to the adapter case.

[0009] Next, a second invention is a gas meter according to the first invention, in which the measurement unit has a measurement pipe for measuring a gas flow rate, a holding case for housing and holding the measurement pipe, and a measurement pipe cover for covering the measurement pipe housed in the holding case. An annular seal member is attached to the outer periphery of the measurement unit, which seals a gap between the measurement unit and the main body and a gap between the measurement unit and the adapter case when the measurement adapter is attached to the main body, and holds the holding case, the measurement pipe, and the measurement pipe cover together.

[0010] Next, the third invention is a gas meter according to the second invention, wherein the measurement pipe has a measurement inlet through which the gas to be measured flows in and a measurement outlet through which the measured gas flows out, and the holding case has a box-like shape with an opening on the side facing the main body when the measurement adaptor is attached to the main body.The gas meter has a straightening plate for straightening the flow of gas at least one of a position on the holding case facing the measurement inlet of the measurement pipe and a first predetermined distance away from the measurement inlet, and a position on the holding case facing the measurement outlet of the measurement pipe and a second predetermined distance away from the measurement outlet.

[0011] Next, a fourth invention is a gas meter according to the third invention, wherein an outer wall of the box-shaped retaining case is erected at a third predetermined distance from the straightening vane on the opposite side of the measuring pipe from the straightening vane. Effect of the Invention

[0012] According to the first invention, a gas meter corresponding to the gas flow rate desired to be measured can be configured by selecting a measuring unit corresponding to the gas flow rate to be measured from among a plurality of types of measuring units corresponding to the gas flow rate, housing it in an adapter case, and attaching it to the main body. In other words, the main body case and adapter case of the die-cast gas meter can be made common. In other words, by making the measuring adapter housing the measuring unit corresponding to the gas flow rate detachable from the main body having the main body case, it is possible to use a common main body case and a common adapter case, thereby reducing the effort and man-hours.

[0013] According to the second aspect of the present invention, the measurement unit can be appropriately configured according to the gas flow rate. Also, by providing the annular seal member with not only a sealing function but also a holding function for holding the holding case, the measurement tube, and the cover together, the number of holding parts can be reduced.

[0014] According to the third aspect of the present invention, by providing a flow straightening plate at an appropriate position, turbulence of the gas flowing inside the measurement pipe can be suppressed, and the measurement accuracy of the gas flow rate can be appropriately ensured.

[0015] According to the fourth aspect of the present invention, by locating the outer wall of the holding case in an appropriate position, the flow straightening effect of the flow straightening plate can be more appropriately obtained. [Brief description of the drawings]

[0016] [Figure 1] FIG. 2 is a perspective view illustrating an example of the appearance of a gas meter. [Diagram 2] FIG. 2 is an exploded perspective view illustrating the structure of a gas meter. [Diagram 3] 3 is a cross-sectional view taken along line III-III of the gas meter shown in FIG. 1, illustrating the internal structure of a main body and the internal structure of a measurement adapter. FIG. [Figure 4] This is the main body part in FIG. [Diagram 5] This is the measurement adapter in Figure 3. [Figure 6] FIG. 2 is an exploded perspective view illustrating the structure of the measurement unit according to the first embodiment. [Figure 7] 7 is a perspective view illustrating the appearance of the measurement unit in a state in which the members shown in FIG. 6 are assembled. [Figure 8] FIG. 11 is an exploded perspective view illustrating the structure of a measurement unit according to a second embodiment. [Figure 9] FIG. 13 is an exploded perspective view illustrating the structure of a measurement unit according to a third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] An embodiment of the present invention will be described with reference to the drawings. The same reference numbers in the description refer to the same elements having the same functions without duplicate explanation. When the X-axis, Y-axis, and Z-axis are described in the drawings, the X-axis, Y-axis, and Z-axis are mutually perpendicular, and as shown in FIG. 1, the X-axis direction indicates the direction toward the right when the gas meter 1 is viewed from the front. Also, as shown in FIG. 1, the Y-axis direction indicates the depth direction of the gas meter 1, and the Z-axis direction indicates the direction toward the top of the gas meter 1.

[0018] <External appearance of gas meter 1 (Fig. 1)> First, the external appearance of the gas meter 1 will be described with reference to Fig. 1. The gas meter 1 is composed of a main body unit 10 having a main body case 2, and a measurement adaptor 30 having an adaptor case 31. The measurement adaptor 30 is detachable from the main body unit 10.

[0019] The main body 10 includes a substantially box-shaped main body case 2 with openings on the front and bottom, a front panel 4 that serves as a cover for the front opening of the main body case 2, and the like. The main body case 2 and the front panel 4 are, for example, die-cast aluminum products. The main body case 2 is provided with a gas inlet 3a through which gas flows in, and a gas outlet 3b through which gas flows out, and the like. The front panel 4 includes a display window 4a, which is a liquid crystal window that displays the measured gas flow rate, etc., a reset button 4b that resets the gas to a normal operating state from a gas cutoff state due to an earthquake or the like, and a communication terminal cover 5 that covers a communication terminal for connecting a communication device, and the like. The front panel 4 also includes a housing section 4c that houses an electronic circuit board on which a control device (such as a CPU) that controls the operation of the gas meter 1 is mounted.

[0020] The measurement adapter 30 has an adapter case 31 with an open top, and houses a measurement tube 42 (see FIG. 2) for measuring a gas flow rate. The adapter case 31 is, for example, an aluminum die-cast product. The measurement tube 42 has a different size depending on the gas flow rate (gas flow rate range) to be measured, and a measurement tube of a size corresponding to the gas flow rate is housed in the adapter case 31. Then, the measurement adapter 30 housing the measurement tube 42 (see FIG. 2) is attached to the main body 10.

[0021] <Structure of the main body 10 and the measurement adapter 30 constituting the gas meter 1 (FIGS. 2 to 5)> 2, the measurement adaptor 30 includes an adaptor case 31, a gasket 32, and a measurement unit 40. The adapter case 31 housing the measurement unit 40 is attached to the main body 10 as the measurement adaptor 30 with the gasket 32 ​​sandwiched therebetween.

[0022] <Structure of main body 10 (FIGS. 3 and 4)> 4, a body-side mounting opening 11 to which a measurement adaptor 30 is attached is provided on the bottom surface of the body case 2 of the body part 10. The body-side mounting opening 11 has an inlet side opening 12a communicating with the gas inlet 3a and an outlet side opening 12b communicating with the gas outlet 3b. A shutoff valve 21 is installed between the gas inlet 3a and the inlet side opening 12a to shut off gas in the event of an earthquake or the like.

[0023] As shown in Fig. 3, an electronic circuit board 20 is provided inside the main body 10. The electronic circuit board 20 is accommodated in the accommodation portion 4c shown in Fig. 1. On the electronic circuit board 20, as shown in Fig. 3, for example, a liquid crystal circuit M1, integrated circuits M2, M3, and M4 such as a CPU, a return switch S1, connectors C1 and C2, communication terminals T1, T2, T3, and T4, etc. are mounted.

[0024] The liquid crystal circuit M1 is a circuit equipped with a liquid crystal that displays information (such as gas flow rate) in the display window 4a shown in Fig. 1. The integrated circuits M2, M3, and M4 are a control device (CPU), a communication circuit, a circuit for output to the measurement pipe and an input from the measurement pipe, a power supply circuit, etc. Although not shown, a battery (such as a lithium battery) is also accommodated inside the main body case 2.

[0025] The recovery switch S1 is a switch that is turned ON when the recovery button 4b shown in Fig. 1 is pressed. When an earthquake or the like occurs, the control device (CPU) detects the earthquake and operates the shutoff valve 21 to cut off the gas. When the control device (CPU) detects that the recovery switch has been pressed, it operates the shutoff valve 21 to release the cutoff and return the gas meter 1 to a normal operating state.

[0026] In the gas meter 1 of this embodiment, a measurement adapter 30 corresponding to the gas flow rate (gas flow rate range) to be measured is selected and attached to the main body 10, but it is necessary to have the control device execute a measurement program corresponding to the measurement pipe 42 (measurement pipe corresponding to the gas flow rate) contained in the measurement adapter 30.

[0027] An operator connects a communication device such as a personal computer, and writes a measurement program associated with the measurement pipe 42 from the communication device to a Flash-ROM or the like, which is one of the integrated circuits of the electronic circuit board 20. After writing the measurement program, the operator performs a process to prohibit rewriting (such as setting a flag to prohibit rewriting). In the gas meter 1 described in this embodiment, the measurement adapter 30 can be replaced according to a desired gas flow rate (gas flow rate range), and the main body 10, adapter case 31, and gasket 32 ​​(see FIG. 2) are common. Then, the measurement unit 40 is replaced according to the gas flow rate range, and after a measurement program corresponding to the measurement unit 40 is written, rewriting is prohibited.

[0028] The connectors C1 and C2 are provided with terminals for connecting various electronic circuits not mounted on the electronic circuit board 20, such as wiring for the shutoff valve 21 and wiring from the measurement pipe .

[0029] <Structure of the measurement adapter 30 (FIGS. 2, 3, and 5)> As shown in Fig. 5, the measurement adapter 30 has an adapter side mounting opening 33, a measurement inflow space 34a, a measurement outflow space 34b, a measurement unit 40, an adapter case 31, a gasket 32, etc. The adapter case 31 has a substantially box-like shape with the adapter side mounting opening 33 that is open on the top (see Fig. 2), and by accommodating the measurement unit 40, the measurement inflow space 34a and the measurement outflow space 34b are formed (see Fig. 5).

[0030] 3 and 5, the adapter case 31 houses a measurement unit 40 having a measurement tube 42, and is attached to the main body side mounting opening 11 (see FIG. 4) of the main body 10 with a gasket 32 ​​sandwiched therebetween. There are multiple types of measurement adapters 30 (examples of multiple types will be described later) that house measurement units 40 corresponding to the gas flow rates (gas flow rate ranges) that are desired to be measured, and the measurement adapters 30 are replaceable with respect to the main body 10 according to the gas flow rates that are desired to be measured.

[0031] The adapter side mounting opening 33 is an opening that is attached to the main body side mounting opening 11 (see FIG. 4) of the main body 10. The measurement inflow space 34a is a space that communicates with the inflow side opening 12a when the measurement adapter 30 is attached to the main body 10, as shown in FIGS. 3 and 4. The measurement outflow space 34b is a space that communicates with the outflow side opening 12b when the measurement adapter 30 is attached to the main body 10, as shown in FIGS. 3 and 4. In addition, a measurement unit 40 having a measurement tube 42 that measures the gas flow rate that flows from the measurement inflow space 34a to the measurement outflow space 34b is disposed between the measurement inflow space 34a and the measurement outflow space 34b.

[0032] 3, gas that flows into gas meter 1 from gas inlet 3a passes through inlet opening 12a to measurement inlet space 34a, passes through measurement pipe 42 to measurement outlet space 34b, and flows out of gas outlet 3b through outlet opening 12b. The measurement pipe 42 measures the flow rate of the gas passing through.

[0033] <Structure of Measuring Units 40, 40x, 40y According to Gas Flow Rate (FIGS. 6 to 9)> Hereinafter, examples of a plurality of types of measuring units 40 (first embodiment), 40x (second embodiment), and 40y (third embodiment) will be described. The measuring unit 40x shown in FIG. 8 is an example of a measuring unit (measuring unit (for small flow rate)) corresponding to a case where the gas flow rate desired to be measured is relatively low. The measuring unit 40y shown in FIG. 9 is an example of a measuring unit (measuring unit (for large flow rate)) corresponding to a case where the gas flow rate desired to be measured is relatively high. And the measuring unit 40 shown in FIG. 6 and FIG. 7 is an example of a measuring unit (measuring unit (for medium flow rate)) corresponding to a gas flow rate higher than that of the measuring unit 40x and lower than that of the measuring unit 40y.

[0034] The outer sizes of the measurement units 40, 40x, and 40y (the outer size of the part that contacts the main body and the outer size of the part that contacts the adapter case) are all set to be the same. Therefore, the measurement adapter 30 is made so that the measurement unit can be replaced with respect to the common adapter case 31. And, the measurement adapter is made so that it can be attached and detached to the common main body 10 (main body case 2).

[0035] <Structure of the measuring unit 40 according to the first embodiment (FIGS. 6 to 7)> As shown in Fig. 6, the measurement unit 40 of the first embodiment has a retaining case 41, a measurement pipe 42, a measurement pipe cover 43, annular seal members S1a, S1b, S2a, S2b, etc., and the assembled state is shown in Fig. 7. The measurement unit 40 shown in Fig. 6 and Fig. 7 is a measurement unit for a medium flow rate as described above, and is equipped with two measurement pipes 42 mounted on the measurement unit 40x for a small flow rate shown in Fig. 8.

[0036] As shown in Fig. 6, the holding case 41 has a box-like shape with a bottom surface 41b and an opening on the side facing the main body 10 (see Fig. 4) when the measurement adaptor 30 (see Fig. 5) is attached to the main body 10 (see Fig. 4). The holding case 41 is a case that houses and holds two measurement pipes 42, and is provided with a measurement pipe housing recess 41c and straightening plates 41d and 41e corresponding to the housed measurement pipes 42. Since there are two measurement pipes 42, there are two measurement pipe housing recesses 41c corresponding to the two measurement pipes 42, and the straightening plates 41d and 41e are also provided in two places.

[0037] As shown in Fig. 5, the straightening vane 41d is erected at a position facing the measurement inlet 42g of the measurement pipe 42 and spaced from the measurement inlet 42g by a first predetermined distance L1 in the holding case 41. Also, as shown in Fig. 5, the straightening vane 41e is erected at a position spaced from the measurement outlet 42h of the measurement pipe 42 by a second predetermined distance in the holding case 41. Note that it is sufficient that at least one of the straightening vane 41d and the straightening vane 41e is provided. Also, the straightening vanes 41d and 41e are sized to cover almost the entire measurement inlet 42g and the measurement outlet 42h of the measurement pipe 42.

[0038] As shown in FIG. 5, an outer wall 41a of the box-shaped holding case 41 is erected at a position opposite the measuring pipe 42 from the straightening plate 41d, with a third predetermined distance L3 between the straightening plate 41d. An outer wall 41h of the box-shaped holding case 41 is erected at a position opposite the measuring pipe 42 from the straightening plate 41e, with a third predetermined distance L3 between the straightening plate 41e. As shown in FIG. 5, in the measurement inflow space 34a, the straightening plate 41d and the outer wall 41a are provided in the vicinity of the measurement inflow port 42g of the measuring pipe 42. As shown in FIG. 5, in the measurement outflow space 34b, the straightening plate 41e and the outer wall 41h are provided in the vicinity of the measurement outflow port 42h of the measuring pipe 42. As a result, the flow of the gas flowing in the measuring pipe 42 is adjusted, and turbulence is suppressed.

[0039] Further, grooves 41m, 41n are formed on the outer periphery of the holding case 41 into which the annular seal members S1a, S1b are fitted when the holding case 41, the measuring pipe 42, and the measuring pipe cover 43 are assembled together as a single unit, as shown in Fig. 7. The shape and size of the outer periphery of the holding case 41 shown in Figs. 6 and 7, the shape and size of the outer periphery of the holding case 41x shown in Fig. 8, and the shape and size of the outer periphery of the holding case 41y shown in Fig. 9 are the same (they are housed in a common adapter case 31 (see Fig. 3)).

[0040] The measurement pipe 42 has a flow path pipe 42a, an ultrasonic unit 42b, and annular seal members S2a and S2b. The flow path pipe 42a has a generally rectangular tubular shape with a constant cross-sectional area perpendicular to the gas flow direction. The ultrasonic unit 42b transmits and receives ultrasonic waves to measure the flow rate of the gas flowing through the flow path pipe 42a. The ultrasonic unit 42b is connected to a connector 42c to which wiring for a control signal input from a control device (CPU) of the electronic circuit board 20 (see FIG. 3), a detection signal output to the control device (CPU), a power supply, etc. is connected.

[0041] The annular seal members S2a, S2b are fitted into grooves 42m, 42n formed in the flow passage pipe 42a to seal the gap between the measurement pipe cover 43 and the flow passage pipe 42a and the gap between the holding case 41 and the flow passage pipe 42a.

[0042] The measuring pipe cover 43 is a cover that covers the measuring pipe 42 housed and held in the holding case 41, and has an inlet side wall surface 43a and an outlet side wall surface 43b, with a notch 43c and an insertion hole 43d provided corresponding to the housed measuring pipe 42. As shown in Fig. 3, the inlet side wall surface 43a forms a part of the inlet side opening 12a, and the outlet side wall surface 43b forms a part of the outlet side opening 12b. In addition, since there are two measuring pipes 42, there are two notches 43c corresponding to the two measuring pipes 42, and two insertion holes 43d for passing the connector 42c and wiring are also set.

[0043] Grooves 43m, 43n are formed on the outer periphery of the measuring pipe cover 43 into which the annular seal members S1a, S1b are fitted when the retaining case 41, the measuring pipe 42, and the measuring pipe cover 43 are assembled together as a single unit, as shown in Fig. 7. The shape and size of the outer periphery of the measuring pipe cover 43 shown in Figs. 6 and 7, the shape and size of the outer periphery of the measuring pipe cover 43x shown in Fig. 8, and the shape and size of the outer periphery of the measuring pipe cover 43y shown in Fig. 9 are the same (they are housed in a common main body case 2 (see Fig. 3)).

[0044] As described above, in the manufacturing process of the gas meter, the measurement program of the control device (CPU) mounted on the electronic circuit board 20 (see FIG. 3) corresponding to the measurement unit 40 is a measurement program corresponding to the measurement unit 40.

[0045] <Structure of Measuring Unit 40x of Second Embodiment (FIG. 8)> As shown in Fig. 8, the measurement unit 40x of the second embodiment has a holding case 41x, a measurement pipe 42, a measurement pipe cover 43x, annular seal members S1a, S1b, S2a, S2b, etc. The measurement unit 40x shown in Fig. 8 is a measurement unit for a small flow rate as described above, and is equipped with only one measurement pipe 42, whereas the measurement unit 40 for a medium flow rate shown in Fig. 6 is equipped with two measurement pipes 42. Below, differences from the measurement unit 40 shown in Fig. 6 will be mainly described.

[0046] The holding case 41x is a case that holds and accommodates one measuring pipe 42, and is provided with one measuring pipe accommodating recess 41cx and one straightening plate 41dx, 41ex. At least one of the straightening plate 41dx and the straightening plate 41ex needs to be provided. The first predetermined distance L1, the second predetermined distance L2, and the third predetermined distance L3 shown in FIG. 5 are set in the same way as in the case of the holding case 41. The structure of the measuring pipe 42 is the same as the structure of the measuring pipe 42 shown in FIG. 6, so a description thereof will be omitted.

[0047] Since the holding case 41x accommodates one measuring pipe 42, the measuring pipe cover 43x has one notch 43cx and one insertion hole 43dx.

[0048] The shape and size of the outer periphery of the holding case 41x shown in Fig. 8, the shape and size of the outer periphery of the holding case 41 shown in Fig. 6 and Fig. 7, and the shape and size of the outer periphery of the holding case 41y shown in Fig. 9 are the same (housed in a common adapter case 31 (see Fig. 3)). Also, the shape and size of the outer periphery of the measurement pipe cover 43x shown in Fig. 8, the shape and size of the outer periphery of the measurement pipe cover 43 shown in Fig. 6 and Fig. 7, and the shape and size of the outer periphery of the measurement pipe cover 43y shown in Fig. 9 are the same (housed in a common main body case 2 (see Fig. 3)).

[0049] <Structure of measuring unit 40y according to the third embodiment (FIG. 9)> As shown in Fig. 9, the measurement unit 40y of the third embodiment has a holding case 41y, a measurement pipe 42y, a measurement pipe cover 43y, annular seal members S1a, S1b, S3a, S3b, etc. The measurement unit 40y shown in Fig. 9 is a measurement unit for a large flow rate as described above, and the two measurement pipes 42 mounted in the measurement unit 40 for a medium flow rate shown in Fig. 6 are replaced with one measurement pipe 42y having a larger gas flow path (flow path cross-sectional area). Below, differences from the measurement unit 40 shown in Fig. 6 will be mainly described.

[0050] Although there is one measurement pipe 42, the cross-sectional area of ​​the flow passage pipe 42ay perpendicular to the gas flow direction is set to a value larger than the cross-sectional area of ​​the two flow passage pipes 42a shown in Fig. 6. The flow passage pipe 42ay is the same as the flow passage pipe 42a shown in Fig. 6 in that it has a substantially rectangular tubular shape with a constant cross-sectional area perpendicular to the gas flow direction.

[0051] The holding case 41y is a case that holds and accommodates one measuring pipe 42y, and is provided with one measuring pipe accommodation recess 41cy and one straightening plate 41dy, 41ey. At least one of the straightening plate 41dy and the straightening plate 41ey may be provided. The straightening plates 41dy, 41ey are sized to cover almost the entire measuring inlet and measuring outlet of the measuring pipe 42. The first predetermined distance L1, the second predetermined distance L2, and the third predetermined distance L3 shown in FIG. 5 are set in the same way as in the holding case 41.

[0052] Since the holding case 41y accommodates one measuring pipe 42y, the notch 43cy in the measuring pipe cover 43y is a single notch according to the size of the measuring pipe 42y, and the insertion hole 43dy is also a single hole.

[0053] The shape and size of the outer periphery of the holding case 41y shown in Fig. 9, the shape and size of the outer periphery of the holding case 41 shown in Fig. 6 and Fig. 7, and the shape and size of the outer periphery of the holding case 41x shown in Fig. 8 are the same (housed in a common adapter case 31 (see Fig. 3)). Also, the shape and size of the outer periphery of the measurement pipe cover 43y shown in Fig. 9, the shape and size of the outer periphery of the measurement pipe cover 43 shown in Fig. 6 and Fig. 7, and the shape and size of the outer periphery of the measurement pipe cover 43x shown in Fig. 8 are the same (housed in a common main body case 2 (see Fig. 3)).

[0054] Then, a suitable measurement unit is selected from the multiple types of measurement units 40, 40x, 40y, ... according to the gas flow rate (gas flow rate range) desired to be measured by the gas meter 1, and is housed in a common adapter case 31 to configure a measurement adapter, which is then attached to the common main body 10, thereby configuring a gas meter 1 according to the gas flow rate. This eliminates the need to prepare different die-cast main body cases 2 and adapter cases 31 according to different gas flow rates, and it is sufficient to prepare only one type of die-cast main body case 2 and adapter case 31.

[0055] The gas meter 1 of the present invention is not limited to the appearance, shape, configuration, structure, etc. described in this embodiment, and various modifications, additions, and deletions are possible without departing from the gist of the present invention.

[0056] In the description of this embodiment, a gas meter having a measuring pipe that uses ultrasonic waves to measure the gas flow rate is used as an example, but the present invention is not limited to the type that uses ultrasonic waves to measure. Also, as examples of multiple types of measuring units, measuring unit 40 (see FIG. 6), measuring unit 40x (see FIG. 8), and measuring unit 40y (see FIG. 9) are shown, but the multiple types of measuring units are not limited to these three types. [Explanation of symbols]

[0057] 1 Gas meter 2 Main unit case 3a Gas inlet 3b Gas outlet 4 Front Panel 4a Display window 4b Return button 4c Storage section 5 Communication terminal cover 10 Main body 11 Main unit side mounting opening 12a Inflow side opening 12b Outlet side opening 21 Shut-off valve 30 Measurement adapter 31 Adapter case 32 Gasket 33 Adapter side mounting opening 34a Measurement inflow space 34b Measurement outflow space 40, 40x, 40y measuring units 41, 41x, 41y holding case 41b Bottom 41c, 41cx, 41cy Measuring pipe recess 41d, 41dx, 41dy rectifier plate 41e, 41ex, 41ey rectifier plate 41m, 42m, 43m groove 41n, 42n, 43n Groove 42, 42y Measuring pipe 42a, 42ay flow pipe 42b, 42by Ultrasonic unit 42c Connector 42g Measurement inlet 42h Measurement outlet 43, 43x, 43y Measuring tube cover 43a Inlet wall 43b Outlet wall 43c, 43cx, 43cy notch 43d, 43dx, 43dy Through hole C1, C2, 42c Connectors L1 1st predetermined distance L2 2nd predetermined distance L3 3rd predetermined distance M1 LCD circuit M2, M3, M4 integrated circuits S1 Return switch S1a, S1b, S2a, S2b, S3a, S3b Annular seal members T1, T2, T3, T4 communication terminals

Claims

1. A gas meter for measuring a gas flow rate, The gas meter is configured with a main body and a measurement adaptor that is detachable from the main body, The main body portion is A gas inlet through which gas flows in; a gas outlet for discharging gas; a body-side mounting opening to which the measurement adaptor is attached; an inlet side opening provided in the body side mounting opening and communicating with the gas inlet; an outlet side opening provided in the body side mounting opening and communicating with the gas outlet port; having The measurement adapter includes: an adapter-side mounting opening attached to the body-side mounting opening of the body portion; a measurement inflow space that communicates with the inflow side opening when the inflow side opening is attached to the main body; a measurement outflow space that communicates with the outflow side opening when the device is attached to the main body; a measuring unit disposed between the measurement inflow space and the measurement outflow space and configured to measure a gas flow rate flowing from the measurement inflow space to the measurement outflow space; an adapter case that accommodates the measurement unit and has the adapter side mounting opening, the measurement inflow space, and the measurement outflow space formed therein; having The measuring unit is provided in a plurality of types according to the gas flow rate to be measured, the plurality of types of measuring units are set to have the same outer size and are interchangeable with respect to the adapter case; The measuring unit includes: A measuring pipe for measuring a gas flow rate; A holding case that houses and holds the measuring tube; a measuring pipe cover for covering the measuring pipe housed in the holding case; having An annular seal member is attached to the outer periphery of the measurement unit, which seals a gap between the measurement unit and the main body and a gap between the measurement unit and the adapter case when the measurement adapter is attached to the main body, and holds the holding case, the measurement tube, and the measurement tube cover together. Gas meter.

2. A gas meter as claimed in claim 1, The measuring pipe has a measuring inlet through which a gas to be measured flows in and a measuring outlet through which the gas to be measured flows out, the holding case has a box-like shape with an opening on a side facing the main body when the measurement adaptor is attached to the main body, a position in the holding case facing the measurement inlet of the measurement pipe and spaced a first predetermined distance from the measurement inlet; a position in the holding case facing the measurement outlet of the measurement pipe and spaced a second predetermined distance from the measurement outlet; A flow straightening plate for straightening the flow of gas is provided at at least one of the positions. Gas meter.

3. A gas meter as claimed in claim 2, an outer wall of the box-shaped holding case is provided at a position opposite to the measuring pipe with respect to the straightening vane and spaced a third predetermined distance from the straightening vane; Gas meter.

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