Gas meter

Abstract

To provide a gas meter that can reduce the number of components to be assembled into a meter case.SOLUTION: In a gas meter 10, an inflow chamber 30 and a measurement chamber 31 adjacent in a first direction H1 are provided inside a meter case 11, and a fuel gas flowing into the inflow chamber 30 from above being orthogonal to the first direction H1 flows into a measuring tube 50 from the measuring chamber 31 through a through-hole 28 in a first dividing wall 25 between the inflow chamber 30 and the measurement chamber 31. Then, in an event of an abnormality, the through-hole 28 is closed from the inflow chamber 30 side by a valve disc 21 of a shut-off valve 20. In this embodiment, a ring portion 71 is fitted to the inner surface of the through hole 28, and the ring portion 71 is provided with an annular projection 75 as a valve seat that is contacted by the valve disc 21 of the shutoff valve 20 in the event of an abnormality and a partial closing wall 74 to rectify fuel gas. Thus, since the valve seat and the structure for rectifying the flow are formed in one piece, number of parts to be assembled in the meter case 11 can be reduced.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present disclosure relates to a gas meter having a shutoff valve that shuts off the supply of gas into a meter case in the event of an abnormality. [Background technology]

[0002] As this type of gas meter, there is known one in which a valve seat component of a shutoff valve and a rectifier are assembled in a meter case (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2010-008116 A (paragraphs

[0027] ,

[0028] and FIG. 2) Summary of the Invention [Problem to be solved by the invention]

[0004] There is a demand for reducing the number of parts to be assembled into a meter case compared to conventional gas meters. [Means for solving the problem]

[0005] The invention of claim 1 made to achieve the above-mentioned object is a gas meter comprising: a meter case having an inflow chamber adjacent to a measurement chamber for measuring a gas flow rate, in which gas flowing into the inflow chamber from a second direction perpendicular to a first direction in which the measurement chamber and the inflow chamber are aligned flows into the measurement chamber through a through hole penetrating a partition wall between the inflow chamber and the measurement chamber; a rectifier that rectifies the gas flowing from the inflow chamber to the measurement chamber; and a shut-off valve having a valve body that closes the through hole from the inflow chamber side in the event of an abnormality, wherein the rectifier comprises a ring portion that is fitted and fixed into the through hole, and a valve seat that is formed on the ring portion and comes into contact with the valve body in the event of the abnormality.

[0006] The invention of claim 2 is the gas meter of claim 1, wherein the flow straightener is provided with a partial blocking wall blocking part of the inside of the ring portion and a partial opening on the inside of the ring portion that is not blocked by the partial blocking wall, the measurement chamber accommodates a measurement tube having a tubular structure, through which all of the gas passing through the measurement chamber passes and whose end opening faces the partial blocking wall, and the gas flow rate is measured based on the flow velocity of the gas passing through the measurement tube.

[0007] The invention of claim 3 is the gas meter described in claim 2, wherein the partial blocking wall is arranged at the end of the ring portion on the measurement room side, and the side of the partition wall facing the measurement room and the main plane of the partial blocking wall facing the measurement room are arranged flush with each other.

[0008] In the invention of claim 4, an edge portion of the partial closing wall on the partial opening side extends linearly, 4. The gas meter according to claim 2 or 3, wherein the end opening of the measurement pipe is rectangular, and one side of the rectangle is arranged parallel to an edge of the partial blocking wall on the partial opening side.

[0009] The invention of claim 5 is the gas meter according to any one of claims 2 to 4, wherein the partial blocking wall is disposed on the upstream side of the inflow chamber in the through hole.

[0010] The invention of claim 6 is the gas meter according to any one of claims 1 to 5, wherein an axial length of the flow rectifier is smaller than a wall thickness of the partition wall.

[0011] The invention of claim 7 is a gas meter described in any one of claims 1 to 6, wherein the valve body has a disk-shaped gasket superimposed on the surface facing the through hole, and the valve seat is annular, protrudes from the ring portion toward the inlet chamber, and is structured to bite into the gasket. Effect of the Invention

[0012] In the gas meter of the present disclosure, an inflow chamber and a measurement chamber adjacent to each other in a first direction are provided in a meter case, and gas flowing into the inflow chamber from a second direction perpendicular to the first direction flows into the measurement chamber through a through hole provided in a partition wall between the inflow chamber and the measurement chamber, and in the event of an abnormality, a valve body of a shutoff valve closes the through hole from the inflow chamber side to shut off the flow of gas into the measurement chamber. A rectifier for rectifying the gas flowing from the inflow chamber into the measurement chamber is provided in a ring portion that is fitted and fixed to the through hole. Furthermore, the ring portion is also provided with a valve seat against which the valve body of the shutoff valve abuts in the event of an abnormality. In other words, in the gas meter of the present disclosure, the rectifier and the valve seat are integrally formed, so that the number of parts to be assembled into the meter case can be reduced.

[0013] In the gas meter of claim 2, the rectifier has a partial blocking wall that blocks the inside of the ring portion and a partial opening that does not block it. The measurement chamber contains a measurement tube through which all of the gas passing through the measurement chamber passes, and the partial blocking wall faces the end opening of the measurement tube. As a result, even if the gas that has passed through the partial opening of the rectifier is in a turbulent state, it can be rectified so that the gas flowing into the measurement tube is in a laminar flow state by flowing in the second direction along the surface of the partial blocking wall and then changing direction toward the end opening side (first direction) of the measurement tube.

[0014] Furthermore, if the partial blocking wall is disposed on the upstream side of the inflow chamber in the through hole (invention of claim 5), most of the gas flowing into the inflow chamber from the second direction is received by the partial blocking wall. This causes the gas to first flow in the second direction along the surface of the partial blocking wall, then change direction and pass through the partial opening, and then flow in the second direction along the surface of the partial blocking wall again, before changing direction toward the end opening side of the measurement pipe, thereby making it possible to further straighten the gas flowing into the measurement pipe.

[0015] Furthermore, by arranging the partial blocking wall at the end of the ring section on the measurement room side and arranging the main plane of the partial blocking wall on the measurement room side flush with the inner surface of the partition wall on the measurement room side (invention of claim 3), it is possible to suppress an increase in pressure loss in front of the end opening of the measurement pipe. Also, if the end opening of the measurement pipe is rectangular, by arranging one side of the rectangle parallel to the edge of the partial opening side of the partial blocking wall (invention of claim 4), it is possible to make the gas that has flowed along the surface of the partial blocking wall flow uniformly into the measurement pipe.

[0016] Furthermore, as in the gas meter of claim 6, if the axial length of the rectifier is configured to be smaller than the wall thickness of the partition wall, the gas flowing into the measurement chamber can be rectified with a compact structure that fits inside the through hole.

[0017] In addition, as in the gas meter of claim 7, the valve seat may be configured, for example, to have a structure that protrudes in an annular shape from the ring portion toward the inlet room side, and to bite into a disk-shaped gasket that is provided on top of the surface of the valve body of the shut-off valve that faces the through-hole side, thereby blocking the through-hole. [Brief description of the drawings]

[0018] [Figure 1] FIG. 1 is a perspective view of a gas meter according to an embodiment of the present invention; [Diagram 2] Exploded perspective view of a gas meter [Diagram 3] Front cross-sectional view of gas meter [Figure 4] A perspective view of the gas meter with the front cover and front lid removed [Diagram 5] (A) Perspective view of the rectifier from the measurement room, (B) Perspective view from the inlet room [Figure 6] 1 is a perspective view of a valve body of a shutoff valve; [Figure 7] Enlarged cross-sectional view of a gas meter [Figure 8] 1A is a perspective view of a flow rectifier according to another embodiment, and FIG. 1B is a perspective view of the flow rectifier according to another embodiment, as seen from the inlet chamber. [Figure 9] FIG. 13 is an enlarged front cross-sectional view of a gas meter according to another embodiment. [Figure 10]FIG. 13 is an enlarged front cross-sectional view of a gas meter according to another embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] A gas meter 10A of this embodiment will be described below with reference to Figures 1 to 7. The gas meter 10A of this embodiment is a so-called ultrasonic flowmeter that measures the flow rate of fuel gas by using ultrasonic waves, and includes a cutoff valve 20 (see Figure 2), a measurement pipe 50 (see Figure 3), a rectifier 70 (see Figure 3), etc., housed in a meter case 11 connected to the middle of a gas pipe 99.

[0020] The meter case 11 is, for example, an aluminum die-cast product, and has a duct portion 12 that is a substantially rectangular parallelepiped extending in the horizontal direction. Hereinafter, the first horizontal direction in which the duct portion 12 extends is referred to as the "first direction H1," and the second horizontal direction perpendicular thereto is referred to as the "front-rear direction H2." In addition, in the front-rear direction H2, the side having the front flange 16 described below is referred to as the "front side," etc., and the opposite side is referred to as the "rear side," etc. The up-down direction corresponds to the "second direction" in the claims.

[0021] As shown in FIG. 2, the hood section 13 is provided with a left side opening 10K on the left side of the duct section 12 when viewed from the front (hereinafter, simply referred to as the "left side" and the opposite side simply referred to as the "right side"). The hood section 13 is provided with chamfered inclined walls 35 at the four corners. Furthermore, a rectangular frame-shaped protruding wall 36 protrudes from the opening edge of the left side opening 10K. An annular O-ring groove 36A is formed on the end face of the frame-shaped protruding wall 36, and screw holes are formed at the four corners outside the O-ring groove 36A. Then, with an O-ring (not shown) accommodated in the O-ring groove 36A, the left side cover 15 is fitted to the frame-shaped protruding wall 36 and screwed in place. This seals the left side opening 10K of the hood section 13.

[0022] The space between the hood portion 13 and the duct portion 12 is partitioned by a valve mounting wall 14. The inside of the duct portion 12 is partitioned into an inflow chamber 30, a measurement chamber 31, an intermediate chamber 32, and an outflow chamber 33, which are also arranged in order, by first to third partition walls 25, 26, and 27 arranged in order in a first direction H1 from the valve mounting wall 14 side, as shown in Fig. 3. The first partition wall 25 corresponds to the "partition wall" in the claims.

[0023] As shown in Fig. 3, the duct portion 12 is provided on the right side as viewed from the front with a right side opening 33K to which the outflow chamber 33 is open, and a rectangular frame-shaped protruding wall 37 protrudes from the opening edge of the right side opening 33K. With an O-ring (not shown) housed in an annular O-ring groove 37A formed in the frame-shaped protruding wall 37, the right side cover 19 is fitted to the frame-shaped protruding wall 37 and screwed in place to seal the right side opening 33K (see Fig. 4).

[0024] A pair of connecting pipes 23, 24 are protrudingly provided on both the left and right ends of the upper surface of the duct portion 12, and communicate with the inflow chamber 30 and the outflow chamber 33. A gas pipe 99 (see FIG. 2) on the fuel gas supply side is connected to one connecting pipe 23 communicating with the inflow chamber 30, while a gas pipe 99 on the fuel gas user side is connected to the other connecting pipe 24 communicating with the outflow chamber 33.

[0025] As shown in FIG. 3, a circular side through-hole 14A is formed in the valve mounting wall 14, and a circular through-hole 28 is formed in the first partition wall 25 at a position opposite to the side through-hole 14A in the first direction H1 and concentric with the side through-hole 14A. A rectifier 70, which will be described later, is fitted into the through-hole 28. As shown in FIG. 2, the fixing flange 20F of the shutoff valve 20 is fitted to the opening edge of the side through-hole 14A on the hood section 13 side with a packing (not shown) sandwiched therebetween and screwed, so that the valve body 21 of the shutoff valve 20 is accommodated in the inflow chamber 30, and the inside of the hood section 13 forms a valve accommodation chamber 13K in which the drive source 22 of the shutoff valve 20 and the fixing flange 20F are accommodated. The fitting structure between the through-hole 28 and the rectifier 70 will be described in detail later.

[0026] As shown in Fig. 4, a front flange 16 is provided on the front surface of the meter case 11. The front flange 16 has an outer edge portion that forms a horizontally long rectangle, and extends vertically from the duct portion 12, with the left end portion in the first direction H1 being integrated with the hood portion 13. In addition, the entire front surface of the front flange 16 except for the outer edge portion is recessed in a stepped shape to form a recessed portion 16A, and a front opening 17 that opens the front surfaces of the measurement chamber 31, the intermediate chamber 32, and the outflow chamber 33 is formed within the recessed portion 16A.

[0027] The above-mentioned measuring pipe 50 has a square tube shape, and a pair of frame-shaped seal members 60 are fitted in positions near both ends of the measuring pipe 50 (see FIG. 4). Correspondingly, rectangular cutout portions 29 that open on the front opening 17 side are formed in the second and third partition walls 26 and 27. The pair of frame-shaped seal members 60 are fitted into the rectangular cutout portions 29, respectively, and the measuring pipe 50 extends in the first direction H1 to communicate between the measuring chamber 31 and the outflow chamber 33. At this time, the end opening 50A, which is the inlet of the measuring pipe 50, faces the through hole 28 of the first partition wall 25 in the first direction H1 (see FIG. 3). Specifically, the end opening 50A is arranged to face the upper half of the opening portion of the through hole 28. The measuring pipe 50 also has a pair of ultrasonic elements (not shown) built in, and a control circuit on a circuit board 98 (see FIG. 1) calculates the amount of gas used based on the propagation time it takes for an ultrasonic wave transmitted from one ultrasonic element to propagate through the fuel gas and be received by the other ultrasonic element.

[0028] 2, the front opening 17 is closed by a front cover 18, which is a rectangular plate slightly larger than the front opening 17, and has its outer periphery screwed to the meter case 11. At this time, a packing (not shown) is placed on the inner surface of the front cover 18, and the space between the measurement chamber 31 and the intermediate chamber 32, and the space between the intermediate chamber 32 and the outflow chamber 33 are partitioned in an airtight state.

[0029] A cable insertion hole 18A is formed in a portion of the front cover 18 facing the intermediate chamber 32, and a cable (not shown) of the ultrasonic element of the measuring pipe 50 is pulled out to the front side of the front cover 18 through the cable insertion hole 18A. Also, as shown in Fig. 4, a cable insertion hole 16B communicating with the valve accommodation chamber 13K is provided in the upper left side of the recessed portion 16A, and a cable (not shown) of the shutoff valve 20 is pulled out to the front side of the recessed portion 16A through the cable insertion hole 16B. Also, a sensor mounting hole 16C communicating with the inflow chamber 30 is formed in the recessed portion 16A below the cable insertion hole 16B, and a pressure sensor (not shown) is attached to cover the sensor mounting hole 16C.

[0030] A circuit board 98 is attached to the front side of the front cover 18 in a layered manner in the recess 16A. Then, a front cover 81 is attached so as to cover the circuit board 98 (see FIG. 1). An ultrasonic element, a shutoff valve 20, and a pressure sensor are connected to the circuit board 98, and a battery (not shown) housed in the front cover 81 is connected to the circuit board 98 as a power source. Then, the flow rate of the fuel gas is measured by the control circuit mounted on the circuit board 98 using the ultrasonic element as described above.

[0031] Furthermore, power is supplied to the shutoff valve 20 via a switch on the circuit board 98, and normally the valve body 21 is separated from the through hole 28 (the state in FIG. 3). When an abnormality in the gas pressure is detected by the pressure sensor, power to the shutoff valve 20 is cut off, and the valve body 21 closes the through hole 28. A vibration detector is also mounted on the circuit board 98, and when the vibration detector detects vibrations equal to or greater than a reference value, power to the shutoff valve 20 is also cut off, and the through hole 28 is closed.

[0032] In this embodiment, as described above, the rectifier 70 is fitted into the through hole 28 that communicates between the inflow chamber 30 and the measurement chamber 31, and the flow of fuel gas flowing from the inflow chamber 30 to the measurement chamber 31 is made uniform (see FIG. 3). Specifically, the rectifier 70 is an aluminum or brass molded product, and has a structure including a ring portion 71, partial blocking walls 74 disposed at both axial ends of the ring portion 71, and an annular protrusion 75, as shown in FIGS. 5(A) and (B).

[0033] 7, the ring portion 71 is fitted and fixed to the inner surface of the through hole 28. Specifically, the ring portion 71 has a peripheral surface that is concentric with the through hole 28 and parallel to the first direction H1, and a first step surface 71D that expands in diameter in a stepped manner on the inflow chamber 30 side is formed in an axially intermediate portion of the outer peripheral surface, with a large outer diameter portion 72 on the inflow chamber 30 side from the first step surface 71D and a small outer diameter portion 73 on the measurement chamber side 31 from the first step surface 71D.

[0034] The partial blocking wall 74 is provided on the end surface of the ring portion 71 on the side of the small outer diameter portion 73. As shown in FIG. 5(A), the partial blocking wall 74 is substantially semicircular and blocks the upper half of the inner opening of the ring portion 71, and the lower half of the inner opening of the ring portion 71 is a partial opening 74K that is not blocked by the partial blocking wall 74. As shown in FIG. 7, the partial blocking wall 74 faces the entire end opening 50A of the measuring pipe 50 in the first direction H1, and the straight line portion of the lower edge of the partial blocking wall 74 is disposed below the end opening 50A of the measuring pipe 50. Also, the straight line portion of the lower edge of the partial blocking wall 74 is disposed parallel to the lower side of the end opening 50A of the measuring pipe 50. The thickness of the partial blocking wall 74 is substantially the same as the radial thickness of the small outer diameter portion 73 of the ring portion 71.

[0035] The annular protrusion 75 protrudes in the first direction H1 from the end face of the ring portion 71 on the side of the large outer diameter portion 72. As shown in Fig. 7, the annular protrusion 75 has a tapered surface 75T on the tip side of its outer circumferential surface, the diameter of which decreases toward the tip, and the tip surface is an arcuate surface 75C that is chamfered in an arc shape. The inner circumferential surface of the annular protrusion 75 is flush with the inner circumferential surface of the ring portion 71. The radial thickness of the annular protrusion 75 is slightly larger than the radial thickness of the small outer diameter portion 73 of the ring portion 71.

[0036] The annular protrusion 75 serves as a valve seat against which the valve body 21 abuts when the current supply to the shutoff valve 20 is cut off. Specifically, the valve body 21 has a disk shape concentric with the through hole 28, and as shown in Fig. 6, a protrusion 21T having a triangular shape in a plan view is provided in the center of the side surface 21A facing the through hole 28. A packing (not shown) made of rubber or the like is attached to the protrusion 21T, and the surface of the valve body 21 facing the through hole 28 has a flat shape. The packing is engaged with the arc surface 75C of the annular protrusion 75, sealing the gap between the valve body 21 and the annular protrusion 75 and closing the through hole 28.

[0037] Here, as shown in FIG. 7, a second step surface 28D is formed on the inner surface of the through hole 28 into which the ring portion 71 of the rectifier 70 is fitted, the second step surface 28D expanding in diameter in a stepped manner on the inflow chamber 30 side, and the first inner surface 28A is formed on the inflow chamber 30 side from the second step surface 28D, and the second inner surface 28B is formed on the measurement chamber 31 side from the second step surface 25D, the second inner surface 28B having a smaller diameter than the first inner surface 28A. The second inner surface 28B has a circumferential surface parallel to the first direction H1 and has approximately the same diameter as the outer diameter of the small outer diameter portion 73 of the ring portion 71, while the first inner surface 28A is a tapered surface whose diameter gradually expands as it moves away from the measurement chamber 31. The inner diameter of the end of the first inner surface 28A away from the measurement chamber 31 is approximately the same diameter as the outer diameter of the large outer diameter portion 72 of the ring portion 71. The outer diameter of the valve body 21 is smaller than the inner diameter of the first inner surface 28A of the through hole 28.

[0038] In this embodiment, as shown in Fig. 7, the inner surface of the inflow chamber 30 is formed in a cylindrical shape that opens at both ends of the side through hole 14A and the through hole 28. That is, the inner surface of the inflow chamber 30 is flush with the first inner surface 28A of the through hole 28 and the inner surface of the side through hole 14A. As described above, the first inner surface 28A of the through hole 28 is a tapered surface that expands in diameter toward the side through hole 14A, and the inner surface of the side through hole 14A is a tapered surface that continues with the first inner surface 28A of the through hole 28. Note that an inner surface opening 23A that communicates with one of the connecting pipes 23 is formed on the inner surface of the inflow chamber 30.

[0039] The rectifier 70 is assembled to the meter case 11 before the shutoff valve 20 and fitted into the through hole 28. Specifically, the rectifier 70 is inserted in the first direction H1 from the side through hole 14A of the valve mounting wall 14. Then, when the rectifier 70 is inserted to the back of the through hole 28, the first step surface 71D of the ring portion 71 abuts against the second step surface 28D of the through hole 28, the small outer diameter portion 73 of the ring portion 71 fits into the second inner surface 28B of the through hole 28, and the large outer diameter portion 72 of the ring portion 71 is pressed against the first inner surface 28A of the through hole 28. Then, the rectifier 70 is fixed to the inner surface of the through hole 28 by a sealant that is applied in advance to the outer surface of the ring portion 71. At this time, the main plane 74A of the partial blocking wall 74 facing the measurement chamber 31 is positioned so as to be flush with the side surface 25A of the first partition wall 25 facing the measurement chamber 31. On the other hand, the tip of the annular protrusion 75 is disposed so as not to protrude from the through hole 28 in the first direction H1.

[0040] The configuration of the gas meter 10A of this embodiment has been described above. Next, the operation and effect of the gas meter 10A will be described. In the gas meter 10A of this embodiment, as shown in FIG. 3, the fuel gas from the piping 99 of the gas supply source flows downward through one of the connecting pipes 23 and into the meter case 11. In the meter case 11, the fuel gas flows through the inflow chamber 30, the measurement chamber 31, the measurement pipe 50, and the outflow chamber 33, which are arranged in the first direction H1, in that order, and then flows upward through the other connecting pipe 24 and out into the piping 99 on the fuel gas user side. Then, the flow rate is measured using a pair of ultrasonic elements attached to the measurement pipe 50. Here, in the event of an abnormality, the through hole 28 provided in the first partition wall 25 separating the inflow chamber 30 and the measurement chamber 31 is blocked from the inflow chamber 30 side by the valve body 21 of the shutoff valve 20, and the inflow of the fuel gas into the measurement chamber 31 is shut off. In this embodiment, a ring portion 71 is provided that fits into the inner surface of the through hole 28, and the ring portion 71 is provided with an annular protrusion 75 serving as a valve seat against which the valve body 21 of the shutoff valve 20 abuts in the event of an abnormality, and a partial blocking wall 74 for rectifying the flow of fuel gas flowing into the measuring pipe 50. In this manner, in the gas meter 10A of this embodiment, the valve seat and the structure for rectifying the flow are integrally formed, so that the number of parts to be assembled to the meter case 11 can be reduced.

[0041] The partial blocking wall 74 faces the entire end opening 50A of the measuring tube 50 in the first direction H1 inside the ring portion 71. Therefore, even if the fuel gas flowing into the inlet chamber 30 is in a turbulent state when it passes through a partial opening 74K inside the ring portion 71 that is not provided with a partial blocking wall 74, the fuel gas can be rectified so that it becomes in a laminar flow state by flowing upward along the surface of the partial blocking wall 74 and then changing direction toward the end opening 50A of the measuring tube 50 (first direction H1).

[0042] Moreover, the partial blocking wall 74 covers the upper half of the inside of the ring portion 71, and since the fuel gas flows from one connecting pipe 23 from above to below into the inflow chamber 30, the partial blocking wall 74 covers the inflow chamber 30 from the upstream side. Therefore, most of the fuel gas flowing from one connecting pipe 23 into the inflow chamber 30 is received by the partial blocking wall 74. As a result, the fuel gas first flows downward along the surface of the partial blocking wall 74, then changes direction and passes through the partial opening 74K, and then further flows upward along the surface of the partial blocking wall 74, before changing direction toward the end opening 50A of the measurement pipe 50 (see FIG. 7), so that the fuel gas flowing into the measurement pipe 50 can be further rectified.

[0043] Furthermore, in this embodiment, since the main plane 74A of the partial blocking wall 74 is disposed flush with the side surface 25A of the first partition wall 25, it is possible to suppress an increase in pressure loss in front of the end opening 50A of the measuring pipe 50. Also, since the straight part of the lower edge of the partial blocking wall 74 is disposed parallel to the lower side of the end opening 50A of the measuring pipe 50, it is possible to make the fuel gas that has flowed along the surface of the partial blocking wall 74 flow into the measuring pipe 50 evenly.

[0044] Moreover, in the gas meter 10A of the present embodiment, the axial length of the rectifier 70 is smaller than the wall thickness of the first partition wall 25, so that the fuel gas flowing into the measurement pipe can be rectified with a compact structure that fits inside the through hole 28.

[0045] Also, the rectifier 70 can be easily assembled since it can be positioned by inserting it into the inflow chamber 30 from the side through hole 14A of the meter case 11 and abutting the first step surface 71D of the ring portion 71 against the second step surface 28D of the through hole 28. Moreover, the inner surface of the inflow chamber 30 is a cylindrical inner surface that opens at the side through hole 14A and the through hole 28 and expands in diameter toward the side through hole 14, and has a shape including the second step surface 28D that expands in diameter on the side through hole 14A side, so no complicated machining is required.

[0046] [Other embodiments] (1) As shown in Fig. 8(A) and (B), a plurality of ventilation holes 74T may be formed penetrating the partial blocking wall 74. According to this configuration, the flow of the fuel gas flowing into the inflow chamber 30 is made uniform by passing through the plurality of ventilation holes 74T. Note that each ventilation hole 74T may be configured to have a regular hexagon with a pair of opposite sides extending in the up-down direction, for example, and arranged on a plurality of imaginary circles concentric with the partial blocking wall 74.

[0047] Alternatively, the partial blocking wall 74 may block the entire inside of the ring portion 71, and a plurality of ventilation holes 74T may be formed throughout the partial blocking wall 74.

[0048] (2) The rectifier 70 of the gas meter 10A in the above embodiment was configured so that the main plane 74A of the partial blocking wall 74 was arranged flush with the side surface 25A of the first partition wall 25. However, as in the gas meter 10B shown in FIG. 9, the main plane 74A of the partial blocking wall 74 may protrude toward the measurement pipe 50 further than the side surface 25A of the first partition wall 25.

[0049] (3) In the gas meters 10A and 10B of the above-described embodiments, the partial blocking wall 74 is disposed at the end of the ring portion 71 on the measurement room 31 side. However, the partial blocking wall 74 may be disposed in the middle portion of the ring portion 71 in the axial direction.

[0050] (4) In the gas meters 10A and 10B of the above-described embodiments, the tip of the annular protrusion 75 is positioned so as not to protrude from the through hole 28 in the first direction H1. However, the tip may protrude from the through hole 28 in the first direction H1.

[0051] (5) In the gas meters 10A and 10B of the above-described embodiments, the rectifier 70 is an aluminum or brass molded product. However, the rectifier 70 may be a resin molded product.

[0052] (6) In the gas meters 10A and 10B of the above embodiments, the ring portion 71 was configured to include the annular protrusion 75 and the partial blocking wall 74. However, for example, as in the gas meter 10C shown in FIG. 10, the annular protrusion 75 serving as the valve seat may be eliminated from the rectifier 70C. Instead, a ring-shaped protrusion 21B may be provided on the valve body 21 of the shutoff valve 20, and a tapered surface 28T may be provided with the protrusion 21B abutting against the opening edge of the through hole 28 on the inlet chamber 30 side.

[0053] (7) In the gas meters 10A, 10B, and 10C of the above-described embodiments, the duct portion 12 extends horizontally and the pair of connecting pipes 23, 24 protrude upward. However, the present invention may be applied to a gas meter in which the pair of connecting pipes 23, 24 protrude downward, or a gas meter in which one of the connecting pipes 23, 24 protrudes above and below the duct portion 12, or a gas meter in which the duct portion 12 extends in the vertical direction and the pair of connecting pipes 23, 24 protrude horizontally.

[0054] (8) Although the gas meters 10A, 10B, and 10C in the above-described embodiments are configured to measure the flow rate of fuel gas by using ultrasonic elements, any principle for measuring the flow rate may be used.

[0055] In addition, although this specification and drawings disclose specific examples of the technology included in the scope of the claims, the technology described in the claims is not limited to these specific examples, but includes various modifications and variations of the specific examples, as well as parts of the specific examples taken alone. [Explanation of symbols]

[0056] 10A, 10B, 10C Gas meter 11 Meter case 20. Shutoff valve 21 Valve body 25 First Partition Wall (Partition Wall) 28 Through hole 30 Inflow Room 31 Measurement Room 50 Measuring pipe 50A End Opening 70 rectifier 71 Ring section 74 Partially closed wall 74K partial aperture 75 Annular protrusion (valve seat) H1 1st direction

Claims

1. a meter case having an inflow chamber adjacent to a measurement chamber for measuring a flow rate of a gas, wherein gas flowing into the inflow chamber from a second direction perpendicular to a first direction in which the measurement chamber and the inflow chamber are aligned flows into the measurement chamber through a through hole penetrating a partition wall between the inflow chamber and the measurement chamber; a rectifier that rectifies the gas flowing from the inlet chamber to the measurement chamber; a shutoff valve having a valve body that closes the through hole from the inflow chamber side in the event of an abnormality, The gas meter includes a ring portion, the rectifier being fitted and fixed in the through hole, and a valve seat formed on the ring portion and coming into contact with the valve body in the event of the abnormality.

2. the flow straightener includes a partial blocking wall that blocks a part of an inner side of the ring portion, and a partial opening that is not blocked by the partial blocking wall within the inner side of the ring portion, The measuring chamber contains a measuring pipe having a tubular structure, through which all the gas passing through the measuring chamber passes, and whose end opening faces the partial closing wall; 2. The gas meter according to claim 1, wherein the flow rate of the gas is measured based on a flow velocity of the gas passing through the measuring pipe.

3. the partial blocking wall is disposed at an end of the ring portion on the measurement room side, 3. The gas meter according to claim 2, wherein a side surface of the partition wall facing the measurement room and a main plane of the partial blocking wall facing the measurement room are disposed flush with each other.

4. An edge portion of the partial closing wall on the partial opening side extends linearly, 4. The gas meter according to claim 2, wherein the end opening of the measuring pipe is rectangular, and one side of the rectangle is arranged parallel to an edge of the partial closing wall on the partial opening side.

5. The gas meter according to claim 2 , wherein the partial blocking wall is disposed on an upstream side of the inlet chamber in the through hole.

6. 6. The gas meter according to claim 1, wherein an axial length of the flow straightener is smaller than a wall thickness of the partition wall.

7. The valve body includes a disk-shaped packing overlapped on a surface facing the through hole, 7. The gas meter according to claim 1, wherein the valve seat is annular, protrudes from the ring portion toward the inflow chamber, and is structured to bite into the packing.

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